BY 4.0 license Open Access Published by De Gruyter August 5, 2021

Optical elements from 3D printed polymers

Tomasz Blachowicz, Guido Ehrmann and Andrea Ehrmann
From the journal e-Polymers


3D printing belongs to the emerging technologies of our time. Describing diverse specific techniques, 3D printing enables rapid production of individual objects and creating shapes that would not be produced with other techniques. One of the drawbacks of typical 3D printing processes, however, is the layered structure of the created parts. This is especially problematic in the production of optical elements, which in most cases necessitate highly even surfaces. To meet this challenge, advanced 3D printing techniques as well as other sophisticated solutions can be applied. Here, we give an overview of 3D printed optical elements, such as lenses, mirrors, and waveguides, with a focus on freeform optics and other elements for which 3D printing is especially well suited.

1 Introduction

3D printing enables preparing objects of nearly unlimited shapes in a relatively fast way, without the necessity to prepare a mold or other tools before (1,2). In the fused deposition modeling (FDM) technique, which is most often used in the low-cost range, typical polymers are poly(lactic acid) (PLA), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), or polyamide (PA) as well as different thermoplastic polyurethane filaments (TPU), while other technologies allow for printing different polymers or metals (3). Besides FDM printing, diverse other techniques exist, which will be presented in Section 2. The broad variety of different technologies allows for printing quite different materials, e.g., also hydrogels (4,5). They can be used for diverse applications, such as biomedicine and biotechnology (6,7), filters (8,9), orthoses (10,11,12), recoverable bumpers (13,14), reinforcement of textile fabrics (15,16,17,18), or even parts of spaceships and satellites (19,20). All these techniques have in common that objects are produced layer by layer, while nowadays, due to the possibility to use robotic arms, it is even possible to print layers on arbitrarily shaped objects, in different orientations, and on large scales (21,22,23).

For several applications, the imperfect mechanical properties are problematic (24), while other applications necessitate less wavy surfaces than created with many 3D printing techniques (25). Especially for the creation of optical elements, such as lenses or mirrors, a well-defined surface is of utmost importance. This necessitates in most cases using new 3D printing techniques with small minimum feature sizes. On the other hand, for gratings and other optical elements, the typical waviness of many 3D printed objects may even be useful to reach a certain effect.

Here, we give an overview of recent advances in 3D printing optical elements. Starting with a brief introduction to typical 3D printing techniques used in this area, we present different methods enabling simple and more sophisticated passive and active optical elements.

2 3D printing techniques

In the aforementioned FDM technique, a molten polymer is pressed through a nozzle and deposited on the printing bed or on the previous layer, respectively, to successively build a 3D object from subsequent layers (26). This technique is probably the most well-known one since FDM printers are available in inexpensive versions, affordable also for private people, schools, etc. However, the FDM technique usually results in objects with high waviness due to the production principle.

The first developed 3D printing technique was stereolithography (SLA). Here, the layers of the 3D printed object are built up from a light-sensitive resin that is position-dependent crosslinked by light, typically by a laser. The final objects can have diverse mechanical properties, from hard to elastic to hydrogels (27).

Lithographic techniques are also known for the preparation of nanostructures (28). For the preparation of such smaller-scale features, a photomask is applied on a photoresist, so that subsequent UV irradiation only reaches the open areas and either polymerizes (negative photoresist) or dissolves (positive photoresist) the resist at these positions. The better soluble part of the photoresist is afterward washed away. This process is often used to build a master mold (29).

Another possibility to crosslink a UV-curable resin, reaching quite low feature sizes, is given by two-photon or multi-photon polymerization (30,31). In this technique, the resin has to absorb two or more photons in order to reach an excited state, with the process strength being proportional to the squared light intensity and thus limiting it strongly to the desired position, opposite to the common SLA process.

Other techniques, besides resin-based ones, are selective laser sintering (SLS), in which a laser fuses a thermoplastic powder (32), or inkjet printing, which can be used to print hydrogels, etc. on very small scales due to the low viscosities of the ink (33).

A few other highly specialized 3D printing techniques are available, such as direct laser writing or robot dispensing, working with different materials, and reaching different feature sizes. Table 1 gives an overview of typical minimum feature sizes of the aforementioned 3D printing techniques, as reported in the literature (34). These dimensions are essential to choose the optimum 3D printing technique for the optical element that needs to be prepared. Several examples of 3D printed optical elements are given in the following sections.

Table 1

Resolutions of different 3D printing technologies, reported in the literature, sorted from larger to smaller minimum feature sizes. From ref. (14), originally published under a CC-BY license

Technology Min. feature size (µm) Material Ref.
Selective laser sintering <400 Diverse polymers (32,35)
Fused deposition modeling 200 Diverse polymers (16)
Robot dispensing 200 Hydrogels (33)
Stereolithography 30–70 Photosensitive polymers (17)
3D inkjet printing 28 Photoresist (33)
Resonant direct laser writing 1–4 IP-Dip photoresist (36)
Multiphoton absorption polymerization 1 SU8 photoresist (31)
Two-photon polymerization 0.28–1.5 Photoresists (30)
Direct laser writing 0.085–1.5 Photoresists (37)

3 3D printed lenses

Optical lenses are used in many applications nowadays, from glasses for nearsighted people and reading glasses to microscopes, from lasers to optical systems for lithographic techniques (38,39). The common production steps for preparing glass lenses contain grinding, polishing, and lapping, which can nowadays be performed by computer-controlled machines, in this way increasing reproducibility (40). Besides, precision glass molding techniques can be used especially for irregularly shaped lenses, enabling the production of lenses in a faster way (41,42).

Besides glass lenses, polymer lenses are of increasing importance. Typically, polymer optical lenses differ in optical density, transmittance, and thermal stability from glass lenses (43). Polymer optical lenses can be injection-molded (44), meaning high costs for the mold (45), while microlens arrays can be produced by special inkjet printing methods based on polymeric nanodroplets (46).

3D printed polymer lenses can be found in different dimensions, produced by different techniques from various materials. Since the aforementioned inkjet printing technique is limited to diameters of some millimeters and surface control is low (47), one approach can be based on adding an inkjet-based layer on a larger poly(methyl methacrylate) (PMMA) substrate. Gawedzinski et al. tested this approach for lenses of different diameters and focal lengths, prepared by Luxexcel in comparison with glass lenses from large optics producers (48). They found the composite material to exhibit transmission values above 90% for wavelengths of 500–1,100 nm. Excitation in the wavelength range of 350–500 nm resulted in broad-band fluorescence in the visible range, meaning this material should not be used for fluorescent applications. The peak-to-valley roughness was for the glass lenses in the range of 5–10 nm, equivalent go λ/100 quality, and for the 3D printed lenses in the range of 30–110 nm, which corresponds to often used lenses of λ/10 to λ/4 quality. Similarly, the radius of curvature showed slightly higher deviations from the theoretical values for the 3D printed lenses, while astigmatism and coma were significantly higher in the polymer lenses. Thus, increasing the aperture diameters during testing the optical resolution of the lenses clearly increased the resolution of the commercial lenses, while the surface roughness rather blurred the images in the case of the 3D printed lenses. This shows that these apparently small roughness values in the range of several 10 nm are sufficient to reduce the image quality significantly.

Another modified inkjet printing technique, called Printoptical® technology, was suggested by Assefa et al. (49,50). They used LUX-Opticlear with a refractive index of 1.53 at λ = 588 nm for printing and established an iterative manufacturing process to correct surface shape deviations from a reference plano-convex lens by subsequent measurements of the output-wavefront error using a Mach-Zehnder interferometer and repeated printing of the optimized lens. The effect of this optimization step is shown in Figure 1 (49). In this way, wavefront errors of the order of magnitude ± 1 wavelength could be achieved. The group also mentioned that since only one material was commercially available that could be used for this process, manufacturing achromatic lens systems still necessitates combinations with silicon molding and vacuum casting.

Figure 1 
               (a) 3D printed lens with 25 mm clear aperture; (b) surface profile error before iteration; and (c) surface deviation after five iterations. From ref. (49), originally published under an open-access license.

Figure 1

(a) 3D printed lens with 25 mm clear aperture; (b) surface profile error before iteration; and (c) surface deviation after five iterations. From ref. (49), originally published under an open-access license.

Instead of optimizing the printing process, Vaidya and Solgaard developed a smoothing technique for optical surfaces and tested it on mirrors, concentrator arrays, and immersion lenses (51). The latter were produced from polydimethylsiloxane (PDMS) in hemispherical shape by filling 3D printed molds with PDMS monomer followed by heat-curing for 24 h. Before molding, the 3D printed molds were smoothed by coating the material with a UV-curable polymer blend of methacrylates, acrylates, and urethane-based polymers, which could be used to prepare smooth top layers, fixed well on the mold surface (52). After molding, atomic force microscopy measurements showed a very low surface roughness of the PDM parts of only 1.4 nm, similar to the mold surface roughness, and focal length deviating less than 1.5% from the nominal values.

Shao et al. as well as Chen et al. again suggested another method to avoid the usually occurring steps in concave or convex 3D printed surfaces due to the layer-wise printing process (53,54). For this, they combined projection micro-stereolithography (PµSL) with grayscale exposure and meniscus coating. In PµSL, a dynamic mask is applied to control the photopolymerization of each layer, making this process significantly faster than laser-scanning polymerization processes (55). Together with grayscale photopolymerization and meniscus equilibrium post-curing, very low surface roughness of below 7 nm was reached (Figure 2). Besides, to speed up the process further, this technique was combined with microcontinuous liquid interface production (µCLIP) (56) in which 3D printing is performed in a continuous upward movement of the sample stage, without stopping at defined heights, by applying an oxygen-permeable membrane to inhibit photopolymerization reaction near to it. This process only worked with an optimized membrane, here prepared from PDMS, to avoid increased surface roughness.

Figure 2 
               3D printing of an optically smooth surface using the PµSL system and post-processing steps. (a) Schematic illustration of the PµSL system. A 3D solid model with smooth surfaces shown in panel (b) is approximated as a set of discrete voxels, resulting in the pixelated rough surface shown in (c). (d–g) Surface roughness optimization and the resulting imaging characteristics of 3D-printed lenses using various methods. (d) Lens printed by binary patterns without post-curing process; (e) lens printed by binary patterns and the following meniscus equilibrium post-curing process. The polymerized meniscus structures are illustrated in yellow; (f) lens printed by grayscale photopolymerization without the meniscus equilibrium post-curing process, with the grayscale polymerization providing a smooth transition from the pixelated roughness (marked yellow); and (g) lens printed by grayscale photopolymerization and the following meniscus equilibrium post-curing process. The first column in panels (d–g) shows SEM images of the surface of the printed lenses. Scale bars: 200 µm for panels (d–g), 1 mm for the inset of panel (g). The second column in panels (d–g) shows the recorded images of the printed “NU” test objects taken by the phone camera with the 3D-printed lenses attached. Scale bars: 1 mm. Reprinted from ref. (54), with permission from Wiley.

Figure 2

3D printing of an optically smooth surface using the PµSL system and post-processing steps. (a) Schematic illustration of the PµSL system. A 3D solid model with smooth surfaces shown in panel (b) is approximated as a set of discrete voxels, resulting in the pixelated rough surface shown in (c). (d–g) Surface roughness optimization and the resulting imaging characteristics of 3D-printed lenses using various methods. (d) Lens printed by binary patterns without post-curing process; (e) lens printed by binary patterns and the following meniscus equilibrium post-curing process. The polymerized meniscus structures are illustrated in yellow; (f) lens printed by grayscale photopolymerization without the meniscus equilibrium post-curing process, with the grayscale polymerization providing a smooth transition from the pixelated roughness (marked yellow); and (g) lens printed by grayscale photopolymerization and the following meniscus equilibrium post-curing process. The first column in panels (d–g) shows SEM images of the surface of the printed lenses. Scale bars: 200 µm for panels (d–g), 1 mm for the inset of panel (g). The second column in panels (d–g) shows the recorded images of the printed “NU” test objects taken by the phone camera with the 3D-printed lenses attached. Scale bars: 1 mm. Reprinted from ref. (54), with permission from Wiley.

Two-photon polymerization is another possibility that can be used for high-precision 3D printing. Some groups reported on lenses printed with a commercial microfabrication system from Nanoscribe GmbH. Ristok et al. prepared millimeter-sized spherical and aspherical lenses with the system and compared the first with corresponding glass lenses (57). They found a slightly reduced radius of curvature for the polymer lenses due to shrinking (496 µm instead of 500 µm), only slight differences in the imaging quality of glass and printed lenses, and in general a comparable performance of the 3D printed lenses in comparison with the commercial glass lenses. Similarly, Thiele et al. prepared microlens systems for foveated imaging with the same commercial system (58), and Asadollahbaik et al. used the same technique for the preparation of diffractive Fresnel lenses (59).

The same equipment was used by Weber et al., who developed nano-inks from commercial IP-DIP resin and dielectric nanoparticles as possible lens materials with modified refractive indices (60). They found slightly hazy images only for the highest nanoparticle concentration of 20%, indicating that the composite with this amount of nanoparticles may no longer be homogeneously blended. Here, investigations of the lens geometries were not in the focus of the study. Similarly, combining high- and low-refractive-index polymers, Campbell et al. prepared gradient-index lenses with an inkjet-based process (61).

An SLA system equipped with a digital light processing (DLP) projector was used by Kang et al. to fabricate optical elements (62). The projector works with masks for each layer that are subsequently projected onto the printing polymer. The latter can either be a free-radical system, consisting of a monomer and a photoinitiator, or a cationic system in which a ring-opening process of cyclic ethers, especially epoxides, occurs (63,64). Combining both radical and cationic systems, Kang et al. used the material Somos Waterclear Ultra 10122 with a refractive index of 1.52. For thin layers, they are typically cured from bottom to top, allowing for continuous printing without stopping the printing bed, and without an additional membrane, as used in (53). In addition, grayscale masks were again applied here to avoid the usual steps along the sides of the printed samples, and slicing the element into layers of equal thickness, of equal arc length between subsequent layers, and combining both was applied. In this way, especially using the combo slicing method was shown to be very successful in providing lenses with low staircase effect and high optical performance.

With stereolithography, Kukkonen et al. also managed to prepare nonlinear active optical devices, i.e., devices that were capable of second-harmonic generation, pumped by a femtosecond laser with wavelength 1,195 nm to create a light of 597.5 nm (65). For these special nonlinear lenses, they combined microcrystalline nonlinear active component, urea, or potassium dihydrogen phosphate with a common photopolymerizable polyacrylate-based resin to prepare a resin for SLA printing.

Generally, it can be seen that different approaches can be used to use 3D printing for the preparation of high-quality optical lenses. Most of them are based on inkjet printing, 2-photon polymerization, or sophisticated SLA systems with grayscale masks and continuous printing, while some other approaches concentrate on post-processing of the models themselves or molds from which lenses are prepared.

4 3D printed mirrors

Mirrors are, in their simplest form, flat and relatively easily producible. Nevertheless, there are some approaches in the literature to 3D printed mirrors. One reason to use 3D printing for the production of mirrors is that special curved shapes are necessary. Vaidya and Solgaard, e.g., prepared mirror blanks by the aforementioned surface smoothing technology based on surface coating with a UV-curable polymer mixture (51). Figure 3 shows the parabolic profile directly after printing and the significantly stronger reflecting surface after the smoothing procedure as well as the final metalized mirror.

Figure 3 
               3D-printed parabolic mirrors (a) as printed, (b) after smoothing, and (c) after Al deposition. From ref. (51), originally published under a CC-BY license.

Figure 3

3D-printed parabolic mirrors (a) as printed, (b) after smoothing, and (c) after Al deposition. From ref. (51), originally published under a CC-BY license.

Mici et al. suggested another application of 3D printed mirrors (66). Mirrors in high-energy lasers need a high thermal conductivity to allow for cooling the optical surface, in order to reduce thermal expansion. In this case, cooling channels can directly be integrated into the mirror substrates to allow for active cooling.

Other studies include 3D printed electromechanical actuators for large optical telescope mirrors, enabling deformation of several microns (67,68), or 3D printed lightweight mirror bodies from different metals or polymers such as poly(ether ketone ketone) (PEKK) (69,70).

Generally, as long as no special shapes or additional features are necessary, 3D printing mirrors is not investigated in detail since recently no advantages were visible. However, this changes as soon as freeform optics – used as lenses or mirrors – are necessary.

5 3D printed freeform optics

Freeform optics are optical elements without an axis of rotational invariance, with arbitrary shape and possible additional surface structure (71,72). They allow increasing the performance of an optical system, e.g., in biomedical engineering or green energy, building systems with fewer surfaces and thus smaller dimensions and mass with the reduced necessity of assembly (73,74). Such freeform optics can be used in diverse applications, not just imaging, but also in solar energy concentrators (75) or for illumination with increased efficiency and more freedom of design (76). Freeform optics, in form of lenses or mirrors, are natural candidates for 3D printing.

Recently, Li et al. reported on freeform optics, prepared from optical silicones cured by a pulsed infrared laser, i.e., thermally instead of by UV light (77). They investigated the process parameters, i.e., repetition rate and numerical aperture, and applied a wavelength suitable for the PDMS used in the experiments to print freeform donut-shaped lenses that were optically clear, without yellowing, as visible in Figure 4.

Figure 4 
               3D-printed nonaxially symmetrical PDMS lens. (a) Donut shape lens, (b) donut shape lens showing ray bending, (c) nonaxially symmetry freeform lens, and (d) nonaxially symmetry freeform lens showing ray bending. From ref. (77), originally published under a CC license.

Figure 4

3D-printed nonaxially symmetrical PDMS lens. (a) Donut shape lens, (b) donut shape lens showing ray bending, (c) nonaxially symmetry freeform lens, and (d) nonaxially symmetry freeform lens showing ray bending. From ref. (77), originally published under a CC license.

Hong and Liang used a similar process, followed by a step in which the PDMS is dropped onto the cured lens and cured again to flatten the steps between subsequent layers (78). In this way, they could produce plano-convex and plano-concave lenses and lens arrays with a surface roughness of approx. 15 nm, as compared to approx. 5 nm for the best commercially available glass lenses. Besides, they prepared freeform donut lenses focusing the light onto a ring.

Assefa et al. used the Printoptical® technology with Opticlear polymer also for freeform optics, similar to the aforementioned conventional lenses (79,80,81). Partly, they investigated these lenses by white-light interferometry and surface profile macroscopy as well as in comparison with theoretical examinations by ray tracing software. Similarly, a digital twin (82) approach was used by Sieber et al., who used inkjet-printing of optical freeform surfaces and optimized the printed optics by optimizing the difference surfaces (83).

With two-photon polymerization, Li et al. added a special freeform micro-optics, a flat-end block with different holes, to single-mode fiber probes, and found low optical loss for a wavelength range around 1,300 nm (84). For side-viewing probes, specially designed freeform air-photoresist interfaces in the form of off-axis paraboloidal surfaces were used to create total internal reflection. In this way, imaging of biological samples was possible.

Wei et al. used two-photon direct laser writing to prepare a freeform polarizing beamsplitter for the near IR (85). They applied an inverse-design algorithm to define the desired structure for a wavelength range of 1.3–1.55 µm and printed it with the necessary resolution of 100 nm (approx. 1/15th of the wavelength λ). The 3D printed polarizing beamsplitter reached extinction ratios of up to 5 at the optimum wavelength.

Diverse freeform shapes were produced by common UV-polymerization of different polymers by Farahani et al. (86). They found that for free-standing shapes, such as spirals or also lenses without a plane side, the viscosity of the material strongly influences the printability of the desired shapes, while diverse processing parameters showed a further impact on the result, such as deposition speed and UV irradiation intensity. All parameters had to be optimized fitting to each other to allow for a reproducible production.

For the special application of Raman spectroscopy, Grabe et al. developed cost-effective freeform polymer optics by 3D printing (87). These optical elements were 3D printed by MultiJet Modeling, i.e., by UV photopolymerization, and combined focusing of the laser, collection of the Raman scattered light, and also the mount. For the used laser with a wavelength of 785 nm and max. 0.5 W power, they found a Stokes Raman shift resolution of 6.7/cm.

As these examples show, different freeform optics presented in the literature were printed, e.g., by optical silicones cured by an infrared laser, by inkjet printing, common UV polymerization, or two-photon polymerization, depending on the required smoothness and the corresponding optical quality. Slightly different requirements can be defined for 3D printed optical waveguides, as presented in the next section.

6 3D printed optical waveguides

Optical waveguides are often produced from polymers and used in broadband communications, computer systems, and diverse other applications. They guide light beams, e.g., introduced by a laser or LED, and often combine high- and low-index media as step-index or gradient-index waveguides to optimize total internal reflection. While planar waveguides allow sheet beams to propagate parallel to the surface of a high-index guiding layer, channel waveguides further confine the possible beam orientations (88).

Especially planar and channel waveguides are naturally well-suited to be 3D printed since they do not have to be self-standing, but can be placed on an even substrate. On the other hand, simple optical fibers can just be extruded. Thus, several examples for 3D printed waveguides can be found in the literature.

One possibility to prepare optical fibers is by using a low-cost FDM printer as an extruder. Canning et al. showed that direct drawing of optical fibers from an FDM printer was possible due to the consistent temperature distribution in the nozzle (89). They used this simple method to draw ABS and PETG optical fibers that showed similar propagation losses as standard optical fibers. Besides, they combined ABS and polystyrene, showing losses lower than 1.5 dB/cm at 632 and 1,550 nm and lower than 0.75 dB/cm at 1,064 nm (90). Using a modified nozzle (Figure 5), Talataisong et al. prepared even microstructured polymer optical fibers from a common FDM printer (91). Their fiber showed confinement of light at λ ∼ 1,550 nm in the fiber core with a maximum propagation loss of 1.1 dB/cm.

Figure 5 
               (a) Structured nozzle design. Green arrows and green colors represent the direction of filament moving and cross section of extruded polymer from the structured nozzle. (b–d) Micromachined structured nozzle: (b) body, (c) body + cover, and (d) after MPOF drawing. From ref. (91), originally published under a CC 4.0 license.

Figure 5

(a) Structured nozzle design. Green arrows and green colors represent the direction of filament moving and cross section of extruded polymer from the structured nozzle. (b–d) Micromachined structured nozzle: (b) body, (c) body + cover, and (d) after MPOF drawing. From ref. (91), originally published under a CC 4.0 license.

Other authors report on using 3D printed preforms that are drawn afterward. This approach has the advantage that it is possible to combine two materials with different refractive indices (92). For this case, Toal et al. underline the importance of properly choosing the printing direction of an FDM printer (93). They prepared a broad variety of structured and two-material fibers, produced by drawing 3D printed structures, and showed that even very fine cores could transmit green laser light along the whole fiber length of 9 m.

Zhao et al. prepared fibers with different core geometries, surrounded by claddings from another material, by simultaneous printing of both materials (94). For the mid-IR, Talataisong et al. prepared microstructured hollow fibers from 3D printed PETG preforms and found wave guidance in the wavelength range of 3.5–5 µm inside the hollow fiber core (95).

Besides these drawn waveguides produced by the simple FDM process, there are more complex fabrication methods reported in the literature. Bertoncini and Liberale, e.g., used a two-photon lithography process, applying the commercially available Nanoscribe system to prepare highly complex waveguides from the IP-Dip photoresist (96). With this system, they prepared diverse microstructured optical fibers, e.g., fibers with helically twisted hole arrangements, with photonic bandgap hollow-core, with anti-resonant hollow-core, etc., mostly for a wavelength of the optical mode of 1,060 nm.

Frascella et al. modified the common DLP process by using a photoluminescent dye, which enabled 3D printing waveguides and splitters, guiding the luminescence (97). By copolymerizing the dye together with the printing polymer, the dye’s solvatochromic properties toward different solvents could be maintained, in this way producing solvents’ polarity sensors.

Finally, diverse authors show approaches to use 3D printing for preparing waveguides on substrates, e.g., for optronic sensor networks. Wolfer et al. compared inkjet printing with a UV-curable ink with flexographic printing, a typical industrial-scale photopolymer printing process (98). They underlined the additional possibilities offered by inkjet printing, enabling printing after other structures have already been added onto the substrate, while flexographic printing needs to be the first step in a production cycle. Besides, inkjet-printed micro-lenses could be used as coupling structures at the end of a waveguide (99).

A different approach was chosen by Soma and Ishigure, who used a robot-microdispenser to 3D print graded-index fibers (100). With their so-called mosquito method, they first printed the uncured cladding layer, then inserted the needle of a robot dispenser into this layer, and dispensed the core monomer there linearly. By monomer diffusion between both materials, a round core is formed before the whole system is cured by UV exposure. In this way, they produced a 12-channel polymer parallel multimode optical waveguide with low propagation losses of 0.033 dB/cm at 850 nm, low insertion losses, and low crosstalk. Besides waveguides aligned in one layer, they also showed the possibility to form a 3D waveguide network by this method (101).

A similar approach was chosen by Ishihara et al., who used calixarene, a cyclic phenol resin with lower propagation losses than PMMA, to produce optical waveguides by two-photon polymerization (102). They also inscribed the 3D core into the cladding. While the core was cured by two-photon-assisted polymerization, the residual monomer surrounding the core was afterward polymerized by UV light and built the cladding. In the same way, they also managed to prepare a 1 × 3 splitter.

Quite a different material was used by Parker et al., who used direct ink writing to prepare optical waveguides from silk (103). They prepared a silk fibroin ink from 28% to 30% silk fibroin in an aqueous solution, which was extruded into a coagulation reservoir containing methanol/water where the continuous rodlike filament was formed rapidly. The optical waveguides showed good optical properties, combined with biocompatibility and biodegradability, and offered the possibility to incorporate dopants to use new ways of photoactivation, making this material interesting for new biophotonic sensing devices.

With stretchable clear ballistic gel and a custom-made microextrusion printer (104), Udofia and Zhou prepared straight and curved waveguides with different nozzle diameters, reaching a minimum diameter of 154 µm. Besides structures located in a 2D area, they also printed 3D stacks of waveguides. Interestingly, a low propagation loss of 0.22 dB/cm was reached with this material as well as high transparency, making this material also interesting for 3D printed fluidic devices (105).

Wang et al. used an FDM printer to prepare a 3D stack of waveguides, each prepared from a single printing line, in this way creating an optical faceplate of 20,000 fibers (106). After polishing the ends, they compared four different transparent printing materials and found strong differences in transmission and crosstalk, with limited resolution due to the relatively imprecise printing process.

Besides these pure optical waveguides, several authors introduced special shapes inside the waveguides or at their ends to modify their optical properties. With direct laser writing, Gissibl et al. showed diverse sub-micrometer spherical, toric, and freeform lenses as well as polarizing structures that were compared with simulations (107). They found that the internal refractive index variations upon inhomogeneities during polymerization were not problematic for the optical performance so that the method could be used to prepare new optics for endoscopy or micro-imaging. Direct laser-writing by two-photon polymerization was also suggested by Hadibrata et al. to 3D print a metalens on an optical fiber tip (108). This metalens was inverse-designed and had a focal length of approx. 8 µm at λ = 980 nm, resulting in a spot size of approx. 100 nm and could be used for direct laser lithography. Photopolymerization of SU-8 photoresist by UV light patterns, combined with a digital camera for machine vision metrology, was used in a 3D micro-printing platform to prepare suspended mirror devices on the end face of optical fibers (109).

Generally, 3D printing of optical waveguides is possible by extruding in an FDM printer, printing, and extruding afterward, or in the case of highly sophisticated structures, by the aforementioned high-resolution 3D printing techniques. For simple waveguides with round cross sections, the extrusion in an FDM printer offers a fast and inexpensive production method.

Other important optical elements, directly correlated with optical waveguides, are the optical splitters described in the next section.

7 3D printed beam-splitters

When optical data – or light in general – are propagating through an optical waveguide, there is often the necessity to split or to combine these signals. For this, an optical splitter is used, often Y-shaped. Similar to the waveguides themselves, it is necessary to take into account the dimensions and material parameters to prepare single- or multi-mode beam-splitters.

Prajzler et al., e.g., prepared in-plane beam-splitters by a UV-curable photopolymer, which is inkjet-printed to prepare a mold first (110). Commercially available large-core polymer optical fibers (POFs) from PMMA were inserted into the molds before the Y-shaped beam-splitter was filled into the remaining mold, connecting the POFs, and hardened. Finally, the top cover was again 3D printed. They found insertion losses of 5.4 dB at 532 nm and less than 6.8 dB at higher wavelengths of 650 nm and 850 nm, respectively, combined with a well-balanced coupling ratio between both outputs. Even smaller insertion losses were most recently demonstrated by this group, using optical elastomers for core and cladding (111).

Hasan et al. used an FDM printer to prepare a multimode planar large-core Y-splitter from ABS, with NOA glue used to fill up the core and found sufficient insertion losses of the splitter (112). NOA UV-curing glues were already shown before to be suitable as fiber cores for a broad range from visible light to IR (113).

Besides these 1 × 2 splitters, other groups prepared higher-order beam splitters. Using 3D printing of the UV-resist IP-Dip, Gaso et al. as well as Seyringer et al. prepared 1 × 4 beam splitters (114,115), while Roggero and Hernández-Figueroa prepared a 1 × 10 beam splitter with SU-8 as the core (116), and Tao et al. presented even a 1 × 16 polymeric optical splitter, again with SU-8 as the core polymer (117).

As these few examples show, similar to the preparation of in-plane optical waveguides, optical splitters can also be based on UV-curable polymers or even FDM printers, with the possibility to use the aforementioned NOA glue to avoid too high insertion losses between beam splitters and adjacent waveguides.

8 3D printed whispering-gallery-mode resonators

If an optical field is confined near the surface of a special resonator due to internal reflection, the resonances are called optical whispering-gallery modes (WGM) (118). Such WGMs have an evanescent field that is extended outside the resonator, making them suitable as gas sensors, etc. (119,120).

Several groups investigated possibilities to use 3D printing to prepare such WGM resonators. Wu et al. used a dynamic image projection scheme to develop a SU-8 photoresist (121). They prepared WGM resonators in the form of suspended disks and showed that the WGMs were efficiently excited in the WGM resonator coupled with a tapered optical fiber, as visible in Figure 6. Besides, they measured radius-dependent transmission spectra of the resonators, in good agreement with theoretical calculations.

Figure 6 
               Microscopic images of a WGM resonator coupling with a tapered optical fiber: (a) the tapered optical fiber is far away from the coupling regime and (b) the tapered optical fiber is within the coupled regime. Images were taken applying a 650 nm laser beam into the fiber. From ref. (121), originally published under an open-access license.

Figure 6

Microscopic images of a WGM resonator coupling with a tapered optical fiber: (a) the tapered optical fiber is far away from the coupling regime and (b) the tapered optical fiber is within the coupled regime. Images were taken applying a 650 nm laser beam into the fiber. From ref. (121), originally published under an open-access license.

Similar mushroom-like WGM microcavities were prepared by Ouyang et al. (122,123), while Wu et al. prepared suspended-toroid WGM resonator arrays also by a micro-printing technique based on UV-curing the used resin by a high-speed optical spatial modulator (124).

An interesting application apart from sensing was reported by Tomazio et al. (125), who used a rhodamine-B-doped WGM microcavity as a laser with a very low threshold pump energy of only 12 nJ for free-space pulsed excitation at a wavelength of 532 nm. They prepared a negative-tone photoresist from two acrylate monomers and a photoinitiator to which rhodamine B was added from an ethanol solution. The photoresist was dropped onto a glass substrate, covered by a coverslip with a spacer, and then position-dependent cured with a femtosecond laser. The WGM resonator was found to have high surface quality and low absorption in the wavelength range near 600 nm, making it well suitable as a microlaser.

9 3D printed diffraction elements

3D printed optical diffraction elements are scarcely reported in the literature. Wang et al. used a modified two-photon polymerization process to overcome the problem of insufficient precision of the desired microscopic structures (126). By optimizing laser power, beam scan speed, hatching distance, and slicing distance, they could produce millimeter-scale nearly perfect gratings with diffraction efficiencies near to the theoretical limits, in this way enabling precise wavefront shaping.

Using digital light processing (DLP), Vallejo-Melgarejo et al. produced diffraction gratings from photocurable resin, followed by smoothing the components by sandpaper with increasing grits and polishing with a polishing cloth and a three-step commercial polishing agent (127). Using gratings with layer thicknesses between 10 and 50 µm, they found that the effective slit width fills the entire volume of the printed part, in this way enabling integration of two or more optical devices in one printed object. Here, the layered polymerization apparently influenced the way in which light was diffracted.

Optical gratings from pillars were produced by two-photon polymerization with different laser powers, resulting in different sizes and optical properties, by Purtov et al. (128). In this way, defect-free nanopillars down to diameters of 184 nm were created. By tuning the process parameters, the pillar sizes could be tailored to the desired optical properties.

10 3D printed polarizing optics

Polarizing optics, i.e., optical elements capable of modifying the polarization state of a light beam, are typically polarizers and wave plates (also named retarders), which polarize an unpolarized beam and change the phase of a polarized beam, respectively. Only a few examples for 3D printed polarizing optics can be found in the recent literature.

Polarizers can be produced by integrating dyes by wire-grid polarizers and by using birefringent crystals, such as calcite (129). Apparently, the last type cannot be 3D printed, while especially for wire-grid polarizers, the typical layer structure of 3D printed objects may even be advantageous. In magneto-optical and other measurement applications, however, polarizers necessitate high extinction ratios of 10,000:1 or more (130,131).

Nevertheless, Hahn et al. presented a 3D printed polarizing beam splitter at the end of a single-mode optical fiber (132). The element consisted of a refractive prism combined with an elevated and suspended subwavelength diffraction grating and was 3D printed with the Nanoscribe system. They found a polarization purity above 80% for both beams emerging at +45° and −45°. Wei et al. used two-photon direct laser writing to prepare a freeform NIR polarizing beamsplitter and found extinction ratios around 2–5, mentioning that this value is limited by recent 3D technology (85).

As a retarding element, Bertoncini and Liberale prepared a Fresnel Rhomb by 3D printing (133). This rhomb is actually a rhombohedral prism in which incident light is reflected twice if entering under the right angle, resulting in a phase shift between both incident polarization orientations by 90°. It thus works like a quarter-wave plate, creating circularly polarized light, or if two Fresnel Rhombs are stacked, it can be used as a half-wave plate. Here, a miniaturized Fresnel Rhomb was directly printed on the output face of an optical fiber using direct laser writing by the Nanoscribe system. The authors suggest such miniaturized Fresnel Rhombs for application in circular dichroism or Raman spectroscopy.

Wang et al. used a dielectric geometric phase optical element instead, printed by direct laser writing, to prepare spin–orbit optical vortex generators, of which half-wave plates are a special case, and optical spin splitters (134). Their design consisted of small round dots, split into 16 or more identical parts, in which space-variant gratings were applied in different patterns per part. In this way, different optical vortices could be generated. More recently, Varapnickas et al. prepared dielectric metasurface birefringent optical retarders printed with a similar system and found an even higher polarization conversion efficiency (135). While Liu et al. used two-photon polymerization by femtosecond 3D direct laser writing to prepare common and convex spiral phase plates (Figure 7) (136), Wei et al. prepared spiral phase plates with different topological charges with the same technique (137).

Figure 7 
               (a) Spiral phase plate and (b) convex spiral phase plate containing a convex lens and a spiral phase plate. From ref. (136), originally published under a CC-BY license.

Figure 7

(a) Spiral phase plate and (b) convex spiral phase plate containing a convex lens and a spiral phase plate. From ref. (136), originally published under a CC-BY license.

On the other hand, so-called metamaterials can be used to influence reactions in light of different polarization. Hess et al. presented 3D printable plasmonic metamaterial gels, which contain gold nanorods and cellulose nanocrystals in a liquid crystalline colloidal host, showing polarization-dependent plasmonic properties due to the interaction of all three materials, here by showing different colors for different polarization orientations (138). With pure liquid crystal elastomers, Woska et al. printed flexible substrates for rigid photonic elements as well as tunable photonic structures (139), and He et al. presented an ultra-broadband twisted-nematic diffractive waveplate (140). In order to create metasurfaces for orbital angular momentum multiplexing holography, Ren et al. used two-photon polymerization (141). They produced nanopillars of identical lateral dimensions and 8 different heights having 8 different in-plane rotation angles, leading to a 64-level metasurface which can be used for holographic video displays or optical encryption. Combining SLA printing of mushroom-like and other microstructures with metalizing the surface, Sadeqi et al. prepared diverse metamaterial surfaces with different functionalities for the optical and the Terahertz range (142).

As this short overview shows, in the research area of 3D printed polarization optics, more developments can be expected with increasing printing accuracy.

11 3D printed optical sensors

Among the many possible applications of 3D printed optical elements, sensor applications belong to the most interesting ones. In the simples form, 3D printed contact lenses, prepared by direct laser printing, can contain built-in microchannels at the edges for diagnostic purposes (143,144). A more sophisticated approach was presented by Park et al., who used 3D printing to prepare a whole photodetector (145). They used water-based inks with different functional chemicals or nanoparticles, which were printed layer by layer on a polyethylene terephthalate (PET) film to form a bendable photodetector array in a flat or spherical shape with good performance.

Wei et al. prepared an interferometric pressure sensor by two-photon polymerization, based on a miniaturized optical fiber-based Fabry–Perot interferometer (146). For this, they printed an unsealed cylinder column with a suspended polymer diaphragm on a single-mode fiber tip to create a Fabry–Perot cavity. Testing cavities with different lengths, they showed a linear response to pressure changes in different pressure ranges with different sensitivities, making them usable for pressure sensing applications.

Vapor sensing was enabled by a tower-shaped optical waveguide introduced into a transparent photosensitive resin, prepared by digital light processing (147). The surface waviness due to the layered structure here was supportive to enable vapor sensing, implying that optical scattering changed in the presence of vapor due to polymer–vapor interaction, however, on relatively long time scales.

Wang et al. produced a 3D printed optical sensor to monitor finger flexion, based on the attenuation of light transmitted through crossed polarizers (148). They found a good accuracy of ±0.5° in the whole range from 0° to 90° with high repeatability and stability, together with a fast dynamic response. It must be mentioned, however, that the optical elements here were not 3D printed, but commercially available optics were integrated into 3D printed holders to prepare the whole optical sensor element.

12 Surface improvement for 3D printed optical elements

Generally, improving the surface quality of a 3D printed optical element is only possible to a certain amount since common techniques are more interested in making the surface shiny than in retaining the object’s microscopic dimensions at the same time. Nevertheless, some post-treatment techniques are mentioned in the literature. Ogilvie et al. presented a solvent vapor treatment that bonds microfluidic chips and at the same time reduces the surface roughness from some hundred nanometers to less than 15 nm (149). Szukalski et al. used post-processing by coating the samples with a liquid resin film of thickness 200 µm, followed by UV light curing and washing the uncured residues by isopropyl alcohol, in this way nearly doubling the transmittance (150). Nevertheless, in many cases, the necessary precision and resolution to produce high-quality optical elements have not yet reached with nowadays 3D printing technologies (151). Low-cost optics, however, can in many cases already be 3D printed (152,153), while in other cases, sophisticated solutions to deal with the available surface roughness and waviness were found by diverse research groups.

It should be mentioned that another well-known problem of 3D printed objects, the shrinkage during cooling down, is only scarcely mentioned in the literature. Ristok et al. (57) mentioned a slightly reduced radius of curvature of their 3D printed lenses due to shrinkage. Wang et al. discussed methods to reduce shrinkage and deformation of their printed structures in the supplementary information to their paper (126). Gissibl et al. mentioned the problem of shrinkage and deformation in general but did not experience such problems in their freeform optics (107). Pearre et al. tried to reduce shrinkage by attaching the produced optical elements to larger solid structures (36). Most other papers do not report problems with dimensional stability or shrinkage.

13 Conclusion

Our review shows an emerging number of approaches to use different 3D printing methods to create optical elements. Unexpectedly, even simple techniques such as FDM or SLA can be used in some of these applications, while most optics are produced by more complicated methods such as direct laser writing or two-photon polymerization. In some studies, post-treatment approaches are reported to improve the surface quality, in this way reaching less rough or wavy optical elements than actually possible with a certain 3D printing technique.

Generally, it can be assumed that with further improvements in 3D printing and with new ideas for post-treatment steps, higher-quality optical elements can be produced, in this way enabling producing individual and highly special optics for diverse applications.

  1. Funding information: The study was partly funded by the German Federal Ministry for Economic Affairs and Energy via the AiF, based on a resolution of the German Bundestag, grant number KK5129708TA1, and by the Silesian University of Technology Rector s Grant no. 14/030/RGJ21/00110.

  2. Author contributions: Tomasz Blachowicz: writing – original draft, writing – review and editing, methodology; Guido Ehrmann: writing – original draft, writing – review and editing, methodology; Andrea Ehrmann: writing – original draft, writing – review and editing, methodology.

  3. Conflict of interest: The authors state no conflict of interest.


(1) Ben-Ner A, Siemsen E. Decentralization and localization of production: the organizational and economic consequences of additive manufacturing (3D printing). Calif Manag Rev. 2017;59:5–23. Search in Google Scholar

(2) Duarte LC, Chagas C, Ribeiro LEB, ColtroTomazelli, WK. 3D printing of microfluidic devices with embedded sensing electrodes for generating and measuring the size of microdroplets based on contactless conductivity detection. Sens Actuators B: Chem. 2017;251:427–32. Search in Google Scholar

(3) Noorani R. Rapid prototyping: principles and applications. New Jersey: John Wiley & Sons; 2005. Search in Google Scholar

(4) Zhou SZ, Zhou Q, Lu C, Zhang ZH, Ren LQ. Design and preparation of 3D printing intelligent poly N,N-dimethylacrylamide hydrogel actuators. e-Polymers. 2020;20:273–81. Search in Google Scholar

(5) Chen Z, Zhao D, Liu B, Nian G, Li X, Yin J, et al. 3D printing of multifunctional hydrogels. Adv Funct Mater. 2019;29:1900971. Search in Google Scholar

(6) Donate R, Monzón M, Alemán-Domínguez ME. Additive manufacturing of PLA-based scaffolds intended for bone regeneration and strategies to improve their biological properties. e-Polymers. 2020;20:571–99. Search in Google Scholar

(7) Sölmann S, Ratenholl A, Blattner H, Ehrmann G, Gudermann F, Lütkemeyer D, et al. Mammalian cell adhesion on different 3D printed polymers with varying sterilization methods and acidic treatment. AIMS Bioeng. 2021;8:25–35. Search in Google Scholar

(8) Zang GQ, Li JX, Li J, Zhang CG, Xie JJ, Wang AM. Research on key technology of filter design and forming based on 3D printing technology. J Mater Eng Perform. 2021;30:1139–46. Search in Google Scholar

(9) Kozior T, Mamun A, Trabelsi M, Wortmann M, Sabantina L, Ehrmann A. Electrospinning on 3D printed polymers for mechanically stabilized filter composites. Polymers. 2019;11:2034. Search in Google Scholar

(10) Górski F, Wichniarek R, Kuczko W, Zukowska M, Lulkiewicz M, Zawadzki P. Experimental studies on 3D printing of automatically designed customized wrist-hand orthoses. Materials. 2020;13:4091. Search in Google Scholar

(11) Hale L, Linley E, Kalaskar DM. A digital workflow for design and fabrication of bespoke orthoses using 3D scanning and 3D printing, a patient-based study. Sci Rep. 2020;10:7028. Search in Google Scholar

(12) Chalgham A, Wickenkamp I, Ehrmann A. Mechanical properties of FDM printed PLA parts before and after thermal treatment. Polymers. 2021;13:1239. Search in Google Scholar

(13) Ehrmann G, Ehrmann A. 3D printing of shape memory polymers. J Appl Polym Sci. 2021;138:50847. Search in Google Scholar

(14) Ehrmann G, Ehrmann A. Pressure orientation dependent recovery of 3D-printed PLA objects with varying infill degree. Polymers. 2021;13:1275. Search in Google Scholar

(15) Korger M, Bergschneider J, Lutz M, Mahltig B, Finsterbusch K, Rabe M. Possible applications of 3D printing technology on textile substrates. IOP Conf Series: Mater Sci Eng. 2016;141:012011. Search in Google Scholar

(16) Grothe T, Brockhagen B, Storck JL. Three-dimensional printing resin on different textile substrates using stereolithography: a proof of concept. J Eng Fibers Fabr. 2020;15:1558925020933440. Search in Google Scholar

(17) Sitotaw DB, Ahrendt D, Kyosev Y, Kabish AK. Additive manufacturing and textiles – state of the art. Appl Sci. 2020;10:5033. Search in Google Scholar

(18) Gorlachova M, Mahltig B. 3D-printing on textiles – an investigation on adhesion properties of the produced composite materials. J Polym Res. 2021;28:207. Search in Google Scholar

(19) Blachowicz T, Pajak K, Recha P, Ehrmann A. 3D printing for microsatellites – material requirements and recent developments. AIMS Mater Sci. 2020;7:926–38. Search in Google Scholar

(20) O’Reilly D, Herdrich G, Kavanagh DF. Electric propulsion methods for small satellites: a review. Aerospace. 2021;8:22. Search in Google Scholar

(21) Gosselin C, Duballet R, Roux Ph, Gaudillière N, Dirrenberger J, Morel Ph. Large-scale 3D printing of ultra-high performance concrete – a new process route for architects and builders. Mater Des. 2016;100:102–99. Search in Google Scholar

(22) Brooks BJ, Arif KM, Dirven S, Potgieter J. Robot-assisted 3D printing of biopolymer thin shells. Int J Adv Manuf Technol. 2017;89:957–68. Search in Google Scholar

(23) Zohdi TI. Dynamic thermomechanical modeling and simulation of the design of rapid free-form 3D printing processes with evolutionary machine learning. Comput Methods Appl Mech Eng. 2018;331:343–62. Search in Google Scholar

(24) Kozior T, Blachowicz T, Ehrmann A. Adhesion of 3D printing on textile fabrics – inspiration from and for other research areas. J Eng Fibers Fabr. 2020;15:1558925020910875. Search in Google Scholar

(25) Kozior T, Mamun A, Trabelsi M, Sabantina L, Ehrmann A. Quality of the surface texture and mechanical properties of FDM printed samples after thermal and chemical treatment. Strojniški Vestn – J Mech Eng. 2020;66:105–13. Search in Google Scholar

(26) Moroni L, de Wijn JR, van Blitterswijk CA. 3D fiber-deposited scaffolds for tissue engineering: influence of pores geometry and architecture on dynamic mechanical properties. Biomaterials. 2006;27:974–85. Search in Google Scholar

(27) Wang ZJ, Abdulla R, Parker B, Samanipour R, Ghosh S, Kim KY. A simple and high-resolution stereolithography-based 3D bioprinting system using visible light crosslinkable bioinks. Biofabrication. 2015;7:045009. Search in Google Scholar

(28) Blachowicz T, Kosmalska D, Döpke C, Leiste H, Hahn L, Ehrmann A. Varying steps in hysteresis loops of Co square nano-frames. J Magn Magn Mater. 2019;491:165619. Search in Google Scholar

(29) de Araujo Filho WD, Morales REM, Schneider FK, de Araujo LMP. Microfluidics device manufacturing using the technique of 3D printing. Proc. ASME 12th International Conference on Nanochannels, Microchannels, and Minichannels 2014. New York, NY: ASME; 2014. p. V001T15A002 Search in Google Scholar

(30) Straub M, Gu M. Near-infrared photonic crystals with higher-order bandgaps generated by two-photon photopolymerization. Opt Lett. 2002;27:1824–66. Search in Google Scholar

(31) Kumi G, Yanez C, Belfield KD, Fourkas JT. High-speed multiphoton absorption polymerization: fabrication of microfluidic channels with arbitrary cross-sections and high aspect ratios. Lab a Chip. 2010;8:1057–6060. Search in Google Scholar

(32) Tan KH, Chua CK, Leong KF, Cheah CM, Gui WS, Tan WS, et al. Selective laser sintering of biocompaticle polymers for applications in tissue engineering. Bio-Med Mater Eng. 2005;15:113–24. Search in Google Scholar

(33) Malda J, Visser J, Melchels FP, Jüngst T, Hennink WE, Dhert WJ, et al. Engineering hydrogels for biofabrication. Adv Mater. 2013;25:5011–28. Search in Google Scholar

(34) Blachowicz T, Ehrmann A. 3D printed MEMS technology – recent developments and applications. Micromachines. 2020;11:434. Search in Google Scholar

(35) Zhou WY, Lee SH, Wang M, Cheung WL, Ip WY. Selective laser sintering of porous tissue engineering scaffolds from poly(L-lactide)/carbonated hydroxyapatite nanocomposite microspheres. J Mater Sci: Mater Med. 2008;19:2535–40. Search in Google Scholar

(36) Pearre BW, Michas C, Tsang JM, Gardner TJ, Otchy TM. Fast micron-scale 3D printing with a resonant-scanning two-photon microscope. Addit Manuf. 2019;30:100887. Search in Google Scholar

(37) Thiel M, Fischer J, von Freymann G, Wegener M. Direct laser writing of three-dimensional submicron structures using a continuous-wave laser at 532 nm. Appl Phys Lett. 2010;97:221102. Search in Google Scholar

(38) Fischer RE, Tadic-Galeb B, Yoder PR. Optical system design. New York: McGraw-Hill; 2008. Search in Google Scholar

(39) Voelkel R. Micro-optics: enabling technology for illumination shaping in optical lithography. Proc SPIE. 2014;9052:90521U. Search in Google Scholar

(40) Nicholas DJ, Boon JE. The generation of high precision aspherical surfaces in glass by CNC machining. J Phys D Appl Phys. 1981;14(4):593–600. Search in Google Scholar

(41) Liu W, Zhang L. Thermoforming mechanism of precision glass moulding. Appl Opt. 2015;54(22):6841–99. Search in Google Scholar

(42) Zhang LC, Liu WD. Precision glass molding: toward an optimal fabrication of optical lenses. Front Mech Eng. 2017;12(1):3–17. Search in Google Scholar

(43) Liu JH, Chen XD. Study on the relationship between surface error and optical performance for polymer optical lenses. Optik. 2019;194:163119. Search in Google Scholar

(44) Lo WC, Tsai KM, Hsieh CY. Six Sigma approach to improve surface precision of optical lenses in the injection-molding process. Int J Adv Manuf Technol. 2009;41:885–96. Search in Google Scholar

(45) Schaub MP. The design of plastic optical systems. Bellingham, WA: SPIE Press; 2009. Search in Google Scholar

(46) Li YL, Li TH, Jiao GH, Hu BW, Huo JM, Wang LL. Research on micro-optical lenses fabrication technology. Optik. 2007;118:395–401. Search in Google Scholar

(47) Sung YL, Jeang J, Lee CH, Shih WC. Fabricating optical lenses by inkjet printing and heat-assisted in situ curing of polydimethylsiloxane for smartphone microscopy. J Biomed Opt. 2015;20:047005. Search in Google Scholar

(48) Gawedzinski J, Pawlowski ME, Tkaczyk TS. Quantitative evaluation of performance of 3D printed lenses. Opt Eng. 2017;56(8):084110. Search in Google Scholar

(49) Assefa BG, Pekkarinen M, Partanen H, Biskop J, Turunen J, Saarinen J. Imaging-quality 3D-printed centimeter-scale lens. Opt Exp. 2019;27:12630–37. Search in Google Scholar

(50) Assefa BG, Parnanen H, Pekkarinen M, Biskop J, Turunen J, Saarinen J. Imaging quality 3D-printed inch scale lenses with 10Å surface quality for swift small or medium volume production. SPIE Proc. 2019;10915:1091504. Search in Google Scholar

(51) Vaidya N, Solgaard O. 3D printed optics with nanometer scale surface roughness. Microsyst Nanoeng. 2018;4:18. Search in Google Scholar

(52) Vaidya N, Carver TE, Solgaard O. Device fabrication using 3D printing. US Pat no 62/267,175,2015. Search in Google Scholar

(53) Shao GB, Hai RH, Sun C. 3D printing customized optical lens in minutes. Adv Optical Mater. 2020;8(4):1091646. Search in Google Scholar

(54) Chen X, Liu W, Dong B, Lee J, Ware HOT, Zhang HF, et al. High-speed 3D printing of millimeter-size customized aspheric imaging lenses with sub 7 nm surface roughness. Adv Mater. 2018;30(18):1075683. Search in Google Scholar

(55) Sun C, Fang N, Wu D, Zhang XJS. Projection micro-stereolithography using digital micro-mirror dynamic mask. Sens Actuators A. 2005;121(1):113–20. Search in Google Scholar

(56) Van Lith R, Baker E, Ware H, Yang J, Farsheed AC, Sun C, et al. 3D-printing strong high-resolution antioxidant bioresorbable vascular stents. Adv Mater Technol. 2016;1(9):1066138. Search in Google Scholar

(57) Ristok S, Thiele S, Toulouse A, Herkommer AM, Giessen H. Stitching-free 3D printing of millimeter-sized highly transparent spherical and aspherical optical components. Optical Mater Exp. 2020;10(10):2370–8. Search in Google Scholar

(58) Thiele S, Arzenbacher K, Gissibl T, Giessen H, Herkommer AM. 3D-printed eagle eye: compound microlens system for foveated imaging. Sci Adv. 2017;3:e1602655. Search in Google Scholar

(59) Asadollahbaik A, Thiele S, Weber K, Kumar A, Drozella J, Sterl F, et al. Highly efficient dual-fiber optical trapping with 3D printed diffractive Fresnel lenses. ACS Photo. 2020;7(1):88–97. Search in Google Scholar

(60) Weber K, Werdehausen D, König P, Thiele S, Schmid M, Decker M, et al. Tailored nanocomposites for 3D printed micro-optics. Optical Mater Exp. 2020;10(10):2345–55. Search in Google Scholar

(61) Campbell SD, Brocker DE, Werner DH, Dupuy C, Park SK, Harmon P. Three-dimensional gradient-index optics via inkjet-aided additive manufacturing techniques. IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting; 2015. p. 605–6 Search in Google Scholar

(62) Kang WJ, Hong ZH, Liang RG. 3D printing optics with hybrid material. Appl Opt. 2021;60(7):1809–13. Search in Google Scholar

(63) Cumpston BH, Ananthavel SP, Barlow S, Dyer DL, Ehrlich JE, Erskine LL, et al. Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication. Nature. 1999;398:51–44. Search in Google Scholar

(64) Decker C, Nguyen Thi Viet T, Decker D, Weber-Koehl E. UV-radiation curing of acrylate/epoxide systems. Polymer. 2001;42:5531–41. Search in Google Scholar

(65) Kukkonen E, Lahtinen E, Myllyperkiö P, Konu J, Haukka M. Three-dimensional printing of nonlinear optical lenses. ACS Omega. 2018;3(9):11558–61. Search in Google Scholar

(66) Mici J, Rothenber B, Brisson E, Wicks S, Stubbs DM. Optomechanical performance of 3D-printed mirrors with embedded cooling channels and substructures. SPIE Proc. 2015;9573:957306. Search in Google Scholar

(67) Thetpraphi K, Le MQ, Houachtia A, Cottinet PJ, Petit L, Audigier D, et al. Surface correction control based on plasticized multilayer P(VDF-TrFE-CFE) actuator – live mirror. Adv Optical Mater. 2019;7(13):1900210. Search in Google Scholar

(68) Thetpraphi K, Chaipo S, Kanlayakan W, Cottinet PJ, Le MQ, Petit L, et al. Advanced plasticized electroactive polymers actuators for active optical applications: live mirror. Adv Eng Mater. 2020;22(5):1901540. Search in Google Scholar

(69) Sweeney M, Acreman M, Vettese T, Myatt R, Thompson M. Application and testing of additive manufacturing for mirrors and precision structures. Proc SPIE. 2015;9574:957406. Search in Google Scholar

(70) Ding GJ, He RJ, Zhang KQ, Zhou NP, Xu H. Stereolithography 3D printing of SiC ceramic with potential for lightweight optical mirror. Ceram Int. 2020;46(11B):18785–90. Search in Google Scholar

(71) Garrard K, Bruegge T, Hoffman J, Dow T, Sohn A. Design tools for freeform optics. Proc SPIE. 2005;5874:58740A. Search in Google Scholar

(72) Fang FZ, Zhang XD, Weckenmann A, Zhang GX, Evans C. Manufacturing and measurement of freeform optics. CIRP Ann. 2013;62(2):823–46. Search in Google Scholar

(73) Jiang XJ, Scott PJ, Whitehouse DJ. Freeform surface characterization – a fresh strategy. CIRP Ann – Manuf Technol. 2007;56(1):553–66. Search in Google Scholar

(74) Savio E, de Chiffre L, Schmitt R. Metrology of freeform shaped parts. Metrol Free form Shaped Parts CIRP Ann – Manuf Technol. 2007;56(2):810–35. Search in Google Scholar

(75) Garcia-Botella A, Fernandez-Balbuena AA, Bernabeu E. Elliptical concentrators. Appl Opt. 2006;45:7622–77. Search in Google Scholar

(76) Fournier F, Rolland J. Optimization of freeform lightpipes for light-emitting-diode projectors. Appl Opt. 2008;47:957–66. Search in Google Scholar

(77) Li ZX, Hong ZH, Xiao Y, Hao Q, Liang RG. Thermal effects in single-point curing process for pulsed infrared laser-assisted 3D printing of optics. 3D Print Addit Manuf. 2020;7(4):151–61. Search in Google Scholar

(78) Hong ZH, Liang RG. IR-laser assisted additive freeform optics manufacturing. Sci Rep. 2017;7:7145. Search in Google Scholar

(79) Assefa BG, Pekkarinen M, Saastamoinen T, Biskop J, Kuittinen M, Turunen J, et al. Design and characterization of 3D-printed freeform lenses for random illuminations. Proc SPIE. 2018;10554:105541J. Search in Google Scholar

(80) Assefa BG, Saastamoinen T, Pekkarinne M, Nissinen V, Biskop J, Kuittinen M, et al. Realizing freeform lenses using an optics 3D-printer for industrial based tailored irradiance distribution. OSA Cont. 2019;2(3):690–702. Search in Google Scholar

(81) Assefa BG, Saastamoinen T, Biskop J, Kuittinen M, Turunen J, Saarinen J. 3D printed plano-freeform optics for non-coherent discontinuous beam shaping. Optical Rev. 2018;25:456–62. Search in Google Scholar

(82) Jedrzejowski M, Blachowicz T, Krafczyk W, Pyka W, Tokarczyk O, Chudy M, et al. Analysis of the quasi-stability of kinematic parameters for manipulators system during the docking process using the Digital Twin approach. J Phys Conf Series. in print. Search in Google Scholar

(83) Sieber I, Thelen R, Gengenbach U. Enhancement of high-resolution 3D inkjet-printing of optical freeform surfaces using digital twins. Micromachines. 2021;12(1):35. Search in Google Scholar

(84) Li J, Fejes P, Lorenser D, Quirk BC, Noble PB, Kirk RW, et al. Two-photon polymerisation 3D printed freeform micro-optics for optical coherence tomography fibre probes. Sci Rep. 2018;8:14789. Search in Google Scholar

(85) Wei HM, Callewaert F, Hadibrata W, Velev V, Liu ZZ, Kumar P, et al. Wo-photon direct laser writing of inverse-designed free-form near-infrared polarization beamsplitter. Adv Optical Mater. 2019;7(21):1900513 Search in Google Scholar

(86) Farahani RD, Lebel LL, Therriault D. Processing parameters investigation for the fabrication of self-supported and freeform polymeric microstructures using ultraviolet-assisted three-dimensional printing. J Micromech Microeng. 2014;24:055020. Search in Google Scholar

(87) Grabe T, Li Y, Krauss H, Wolf AG, Wu J, Yao C, et al. Freeform optics design for Raman spectroscopy. Proc SPIE. 2020;11287:112870A. Search in Google Scholar

(88) Ma H, Jen AKY, Dalton LR. Polymer-based optical waveguides: materials, processing, and devices. Adv Mater. 2002;14(19):1339–65. Search in Google Scholar

(89) Canning J, Hossain MA, Han CY, Chartier L, Cook K, Athanaze T. Drawing optical fibers from three-dimensional printers. Optical Lett. 2016;41(23):5551–44. Search in Google Scholar

(90) Canning J, Cook K, Luo YH, Leon-Saval S, Peng GD, Comatti E, et al. 3D printing optical fibre preforms. Asia Communications and Photonics Conference. Hong Kong: OSA; 19–23 November 2015. ASu4B.2. Search in Google Scholar

(91) Talataisong W, Ismaeel R, Sandoghchi SR, Rutirawut T, Topley G, Beresna M, et al. Novel method for manufacturing optical fiber: extrusion and drawing of microstructured polymer optical fibers from a 3D printer. Opt Exp. 2018;26(24):32007–13. Search in Google Scholar

(92) Cook K, Balle G, Canning J, Chartier L, Athanaze T, Hossain MA, et al. Step-index optical fiber drawn from 3D printed preforms. Opt Lett. 2016;41(19):4554–77. Search in Google Scholar

(93) Toal JPM, Holmes LJ, Rodriguez RX, Wetzel ED. Microstructured monofilament via thermal drawing of additively manufactured preforms. Addit Manuf. 2017;16:12–23. Search in Google Scholar

(94) Zhao Q, Tian F, Yang X, Li S, Zhang J, Zhu X, et al. Optical fibers with special shaped cores drawn from 3D printed preforms. Optik. 2017;133:55–60. Search in Google Scholar

(95) Talataisong W, Ismaeel R, Marques THR, Abokhamis Mousavi S, Beresna M, Gouveia MA, et al. Mid-IR hollow-core microstructured fiber drawn from a 3D printed PETG preform. Sci Rep. 2018;8:8113. Search in Google Scholar

(96) Bertoncini A, Liberale C. 3D printed waveguides based on photonic crystal fiber designs for complex fiber-end photonic devices. Optica. 2020;7(11):1487–94. Search in Google Scholar

(97) Frascella F, González G, Bosch P, Angelini A, Chiappone A, Sangermano M, et al. Three-dimensional printed photoluminescent polymeric waveguides. ACS Appl Mater Interfaces. 2018;10(45):39319–26. Search in Google Scholar

(98) Wolfer T, Bollgruen P, Mager D, Overmeyer L, Korvink JG. Printing and preparation of integrated optical waveguides for optronic sensor networks. Mechatronics. 2016;34:119–27. Search in Google Scholar

(99) Jacot-Descombes L, Gullo MR, Cadarso VJ, Brugger J. Fabrication of epoxy spherical microstructures by controlled drop-on-demand inkjet printing. J Micromech Microeng. 2012;22:074012. Search in Google Scholar

(100) Soma K, Ishigure T. Fabrication of a graded-index circular-core polymer parallel optical waveguide using a microdispenser for a high-density optical printed circuit board. IEEE J Sel Top Quant Eletron. 2013;19(2):3600310. Search in Google Scholar

(101) Ishigure T, Suganuma S, Soma K. Three-dimensional high density channel interation of polymer optical waveguide using the mosquito method. 2014 IEEE 64th Electronic Components and Technology Conference (ECTC). New York City, NW: IEEE; 2014. p. 1042–7 Search in Google Scholar

(102) Ishihara J, Komatsu K, Sugihara O, Kaino T. Fabrication of three-dimensional calixarene polymer waveguides using two-photon assisted polymerization. Appl Phys Lett. 2007;90:033511. Search in Google Scholar

(103) Parker ST, Domachuk P, Amsden J, Bressner J, Lewis JA, Kaplan DL, et al. Biocompatible silk printed optical waveguide. Adv Mater. 2009;21(23):2411–55. Search in Google Scholar

(104) Udofia EN, Zhou WC. A guiding framework for microextrusion additive manufacturing. J Manuf Sci Eng Trans ASME. 2019;141(5):50801. Search in Google Scholar

(105) Udofia EN, Zhou WC. 3D printed optics with a soft and stretchable optical material. Addit Manuf. 2020;31:100912. Search in Google Scholar

(106) Wang Y, Gawedzinski J, Pawlowski ME, Tkaczyk TS. 3D printed fiber optic faceplates by custom controlled fused deposition modeling. Opt Exp. 2018;26(12):15362–76. Search in Google Scholar

(107) Gissibl T, Thiele S, Herkommer A, Giessen H. Sub-micrometer accurate free-form optics by three-dimensional printing on single-mode fibres. Nat Comm. 2016;7:11763. Search in Google Scholar

(108) Hadibrata W, Wei HM, Krishnaswamy S, Aydin K. Inverse design and 3D printing of a metalens on an optical fiber tip for direct laser lithography. Nano Lett. 2021;21(6):2422–88. Search in Google Scholar

(109) Yao M, Wu JS, Zhang AP, Tam HY, Wai PKA. Optically 3-D µ-printed ferrule-top polymer suspended-mirror devices. IEEE Sens J. 2017;17(22):7257–61. Search in Google Scholar

(110) Prajzler V, Kulha P, Knietel M, Enser H. Large core plastic planar optical splitter fabricated by 3D printing technology. Opt Commun. 2017;400:38–42. Search in Google Scholar

(111) Prajzler V, Zavrel J. Large core optical elastomer splitter fabricated by using 3D printing pattern. Prepr Res Square. PPR281610. 10.21203/ Search in Google Scholar

(112) Hasan MM, Hoque MM, Jony MMH, Kabir MH. Design of the ABS polymer based multimode planar large core 1 × 2 splitter fabricated by 3D printing technology. 2019 International Conference on Computer, Communication, Chemical, Materials and Electronic Engineering (IC4ME2). New York, NY: IEEE; 2019. p. 1–4 Search in Google Scholar

(113) Prajzler V, Knietel M, Mastera R. Large core optical planar splitter for visible and infrared region. Opt Quant Electron. 2016;48:155. Search in Google Scholar

(114) Gaso P, Pudis D, Seyringer D, Kuzma A, Gajdosova L, Mizera T, et al. 3D polymer based 1x4 beam splitter. J Lightwave Technol. 2021;39(1):154–61. Search in Google Scholar

(115) Seyringer D, Gajdosova L, Gaso P, Jandura D, Pudis D. Experimental verification of 3D polymer based 1 × 4 Y-branch splitter. Proc SPIE. 2020;11378:1137811. Search in Google Scholar

(116) Roggero UFS, Hernández-Figueroa HE. Polymeric power splitters for multiplexing optical biosensors. Opt Laser Technol. 2020;127:106127. Search in Google Scholar

(117) Tao Q, Lu B, Zhai ZS, Cheng J, Liu D. Manufactring a 1x16 air-cladding polymeric optical splitter for electro-optical printed circuit boards by femtosecond laser. Opt Eng. 2020;59(1):017105. Search in Google Scholar

(118) Yang SC, Wang Y, Sun HD. Advances and prospects for whispering gallery mode microcavities. Adv Opt Mater. 2015;3(9):1136–62. Search in Google Scholar

(119) Foreman MR, Swaim JD, Vollmer F. Whispering gallery mode sensors. Adv Opt Photonics. 2015;7(2):168–240. Search in Google Scholar

(120) Keng D, Tan X, Arnold S. Whispering gallery micro-global positioning system for nanoparticle sizing in real time. Appl Phys Lett. 2014;105(7):071105. Search in Google Scholar

(121) Wu JS, Guo X, Zhang AP, Tam HY. Rapid 3D µ-printing of polymer optical whispering-gallery mode resonators. Opt Exp. 2015;23(23):29708–14. Search in Google Scholar

(122) Ouyang X, He JJ, Zhang AP, Tam HY. Optical 3D µ-printing of polymer whispering-gallery-mode microcavity lasers. Frontiers in optics. Washington, DC, USA: OSA; 16–20 September 2018. paper JW3A.27. Search in Google Scholar

(123) Ouyang X, Zhang YX, He JJ, Liang ZT, Zhang AP, Tam HY. 3D µ-printed polymer whispering-gallery-mode microcavity laser sensor array. The European Conference on Lasers and Electro-Optics 2019. Munich, Germany: OSA; 23–27 June 2019. paper ce_11_4 Search in Google Scholar

(124) Wu JS, Guo X, Zhang AP, Tam HY. Rapid 3D micro-printing of optical whispering-gallery mode resonators. IEEE 15th International Conference on Nanotechnology. Rome, Italy: IEEE; 27–30 July 2015. Search in Google Scholar

(125) Tomazio NB, de Boni L, Mendonca CR. Low threshold Rhodamine-doped whispering gallery mode microlasers fabricated by direct laser writing. Sci Rep. 2017;7:8559. Search in Google Scholar

(126) Wang H, Wang HT, Zhang W, Yang JKW. Toward near-perfect diffractive optical elements via nanoscale 3D printing. ACS Nano. 2020;14(8):10452–61. Search in Google Scholar

(127) Vallejo-Melgarejo LD, Reifenberger RG, Newell BA, Narváez-Tovar CA, Garcia-Bravo JM. Characterization of 3D-printed lenses and diffraction gratings made by DLP additive manufacturing. Rapid Prototyp J. 2019;25(10):1684–94. Search in Google Scholar

(128) Purtov J, Rogin P, Verch A, Johansen VE, Hensel R. Nanopillar diffraction gratings by two-photon lithography. Nanomater. 2019;9(10):1495. Search in Google Scholar

(129) Hokari R, Takakuwa K, Kato H, Yamamoto A, Yamaguchi Y, Kurihara K. Low-revlective wire-grid polarizer sheet in the visible region fabricated by a nanoprinting process. Sci Rep. 2021;11:2096. Search in Google Scholar

(130) Tillmanns A, Oertker S, Beschoten B, Güntherodt G, Leighton C, Schuller IK, et al. Magneto-optical study of reversal asymmetry in exchange bias. Appl Phys Lett. 2006;89:202512. Search in Google Scholar

(131) Blachowicz T, Bukowski R, Kleszczewski Z. Fabry-Perot interferometer in Brillouin scattering experiments. Rev Sci Instrum. 1996;67:4057–60. Search in Google Scholar

(132) Hahn V, Kalt S, Sridharan GM, Wegener M, Bhattacharya S. Polarizing beam splitter integrated onto an optical fiber facet. Opt Exp. 2018;26(25):33148–57. Search in Google Scholar

(133) Bertoncini A, Liberale C. Polarization micro-optics: circular polarization from a Fresnel Rhomb 3D printed on an optical fiber. IEEE Photonics Technol Lett. 2018;30(21):1882–55. Search in Google Scholar

(134) Wang XW, Kuchmizhak AA, Brasselet E, Juodkazis S. Dielectric geometric phase optical elements fabricated by femtosecond direct laser writing in photoresist. Appl Phys Lett. 2017;110:181101. Search in Google Scholar

(135) Varapnickas S, Thodika SC, Moroté F, Juodkazis S, Malinauskas M, Brasselet E. Birefringent optical retarders from laser 3D-printed dielectric metasurfaces. Appl Phys Lett. 2021;118:151104. Search in Google Scholar

(136) Liu C, Hu C, Wei D, Chen M, Shi J, Wang H, et al. Generating convergent Laguerre-Gaussian beams based on an arrayed convex spiral phaser fabricated by 3D printing. Micromach. 2020;11(8):771. Search in Google Scholar

(137) Wei HM, Amrithanath AK, Krishnaswamy S. 3D printing of micro-optic spiral phase plates for the generation of optical vortex beams. IEEE Photonics Technol Lett. 2019;31(8):599–602. Search in Google Scholar

(138) Hess AJ, Funk AJ, Liu QK, de la Cruz JA, Sheetah GH, Fleury B. Smalyukh II. Plasmonic metamaterial gels with spatially patterned orientational order via 3D printing. ACS Omega. 2019;4(24):20558–63. Search in Google Scholar

(139) Woska S, Münchinger A, Beutel D, Blasco E, Hessenauer J, Karayel O, et al. Tunable photonic devices by 3D laser printing of liquid crystal elastomers. Optical Mater Exp. 2020;10(11):2928–43. Search in Google Scholar

(140) He ZQ, Tan GJ, Chanca D, Wu ST. Novel liquid crystal photonic devices enabled by two-photon polymerization [Invited]. Opt Exp. 2019;27(8):11472–91. Search in Google Scholar

(141) Ren HR, Fang XY, Jang JH, Bürger J, Rho JS, Maier SA. Complex-amplitude metasurface-based orbital angular momentum holography in momentum space. Nat Nanotechnol. 2020;15:948–55. Search in Google Scholar

(142) Sadeqi A, Nejad HR, Owyeung RE, Sonkusale S. Three dimensional printing of metamaterial embedded geometrical optics (MEGO). Microsyst Nanoeng. 2019;5:16. Search in Google Scholar

(143) Alam F, Elsherif M, AlQattan B, Salih A, Lee SM, Yetisen AK, et al. 3D printed contact lenses. ACS Biomater Sci Eng. 2021;7(2):794–803. Search in Google Scholar

(144) Alam F, Elsherif M, AlQattan B, Ali M, Ahmed IMG, Salih A, et al. Prospects for additive manufacturing in contact lens devices. Adv Eng Mater. 2021;23:2000941. Search in Google Scholar

(145) Park SH, Su R, Jeong J, Guo SZ, Qiu K, Joung D, et al. 3D printed polymer photodetectors. Adv Mater. 2018;30(40):1803980. Search in Google Scholar

(146) Wei HM, Chen MQ, Krishnaswamy S. Three-dimensional-printed Fabry-Perot interferometer on an optical fiber tip for a gas pressure sensor. Appl Opt. 2020;59(7):2173–88. Search in Google Scholar

(147) Swargiary K, Jarutatsanangkoon P, Suwanich P, Jolivot R, Mohammed WS. Single-step 3D-printed integrated optical system and its implementation for a sensing application using digital light processing technology. Appl Opt. 2020;59(1):122–88. Search in Google Scholar

(148) Wang LF, Meydan T, Williams P. Design and evaluation of a 3-D printed optical sensor for monitoring fiber flexion. IEEE Sens J. 2017;17(6):1937–44. Search in Google Scholar

(149) Ogilvie IRG, Sieben VJ, Floquet CFA, Zmijan R, Mowlem MC, Morgan H. Reduction of surface roughness for optical quality microfluidic devices in PMMA and COC. J Micromech Microeng. 2010;20:065016. Search in Google Scholar

(150) Szukalski A, Uttiya S, D'ELia F, Portone A, Pisignano D, Persano L, et al. 3D photo-responsive optical devices manufactured by advanced printing technologies. Proc SPIE. 2019;10915:1091503. Search in Google Scholar

(151) Niesler F, Ganguy Y. 3D printers for the fabrication of micro-optical elements. Opt & Photonik. 2016;11(4):44–77. Search in Google Scholar

(152) Gwamuri J, Pearce JM. Open source 3-D printers: an appropriate technology for building low cost optics labs for the developing communities. ETOP Proceedings, Education and Training in Optics and Photonics 2017. Hangzhou, China; 29–31 May 2017. paper 104522S. Search in Google Scholar

(153) Zhang CL, Anzalone NC, Faria RP, Pearce JM. Open-source 3D printable optics equipment. PLoS ONE. 2013;8(3):e59840. Search in Google Scholar

Received: 2021-06-07
Revised: 2021-07-04
Accepted: 2021-07-08
Published Online: 2021-08-05

© 2021 Tomasz Blachowicz et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.