Microlens fabrication

Biehl S, Danzebrink R, Oliveira P, Aegerter MA. (1998) Refractive microlens fabrication by inkjet process. / Sol-Gel Sci Tech 13 177-182. 

After application of the monomer, subsequent polymerization can then be performed with UV irradiation in an inert gas (nitrogen) atmosphere. An example of a microlens fabricated by this technique is shown in Figure 4.18. 

Figme 7.2 shows the images of the mold and the PDMS microlens fabricated from it. It should be noted that this design caimot modify the light beam along the Z direction. The efficiency of these lenses is then limited to a 2D plane defined by both the X axis and Y axis parallel to the glass substrate—the PDMS layer interface. 

Bellessa J., Rabaste S., Plenet J.C., Dumas J., Mugnier J., Marty 0. doped microcavities fabricated by sol-gel process. Appl. Phys. Lett. 2001 79 2142-2144 Biehl S Danzebrink R., Oliveira P., Aegerter M.A. Refractive microlens fabrication by ink-jet process. J. Sol-Gel Sci. Tech. 1998 13 177-182... 

Chronologically, the oldest approach to microlens fabrication is thermal melting. The action of heat is used to soften or melt convenient material (e.g., germanium in LWIR range) and form it into a desired shape. An alternative is to use material that... 

Tuning of the pre-tilt angle at the interface was also demonstrated by doping commonly used polyimide alignment layers with POSS nanoparticles [339]. In addition, the fabrication of a tunable liquid crystal flat microlens was achieved by placing a drop of a nematic liquid crystal doped with POSS nanoparticles onto a substrate inducing planar alignment (local HAN mode) [340]. Simultaneously, Takatoh and co-workers extended this concept to a series of metal oxide... 

In a somewhat similar fashion, Ishii et alP- have demonstrated inkjet fabrication of polymeric microlenses for optical chip packaging. UV curable epoxy resin is deposited onto optical devices by inkjet printing. When the droplets hit the surface, they form into partial spheres due to their surface tension, and are UV-cured to form the microlens with diameters from 20 to 40 tm with /-numbers of 1.0 to 11.0. Their uniformity in a microlens array was measured to be within 1% in diameter and 3 tm in pitch (total count of 36 lenses). They have also demonstrated hybrid integration of inkjetted microlenses with a wire-bonded vertical-cavity-surface-emitting laser (VCSEL) with coupling efficiencies of 4 dB higher than without the microlens. 

The microlens is an important and key optical component for focusing and collimating light in the microfluidic optical detection system, and can be made up of a hard solid surface or interface (soft solid/liquid, liquid/liquid/...). Hard solid state lenses on-chip are usually fixed focal length lenses similar to the miniaturized traditional lenses used in the free-space detection system. They can be fabricated... 

Y.H. Kim, H.S. Jeong, J.H. Kim, E.K. Yoon, D.K. Yoon, H.-T. Jung, Fabrication of two-dimensional dimple and conical microlens arrays from a highly periodic toroidal-shaped liquid crystal defect array. J. Mater. Chem. 20, 6557-6561 (2010)... 

Microlens arrays have been fabricated by the direct inkjet printing of an UV curable hybrid polymer (17). A periodic pattern of pol3mer drops was inkjet printed on a surface-treated glass substrate and cured by UV light. 

Multiscale microlens arrays can be directly fabricated on a hydrophobic flat surface by a simple inkjet printing technique (20). Inorganic/organic hybrid precursor polymers based on silicones are used. These structures are modified with organic structures that can be eventually crosslinked (21). 

H. S. Ji, J. H. Kim, and S. Kumar, Electrically controllable microlens array fabricated by anisotropic phase separation from hquid-crystal and polymer composite materials. Opt. Lett. 28, 1147 (2003). 

Such biomimetic synthetic microlens arrays could be potentially used as highly timable optical elements for a wide variety of appUcations [246,247, 249]. The successful fabrication of micropatterned single crystals resembling the natural echinoderm calcitic structures demonstrated that the inspiration from Nature s methods of biological manufacture is proving to be a rich reservoir for the fabrication of advanced materials and devices with novel and superior properties. 

Solid microlenses and microlens arrays have been studied and used for more than twenty years [12], Some applications of microlens arrays such as beam shaping [46], focusing light onto CCD arrays [47], and Shack-Hartmann wave-front sensors [10] have been commercialized. Applications of solid microlens arrays are covered extensively in Daly s book [12]. In this book, we will cover some new applications and fabrications of solid microlenses and microlens arrays in Chapter 4, and will focus on tunable microlenses. 

M. H. Wu and G. M. Whitesides, "Fabrication of diffractive and micro-optical elements using microlens projection lithography," Advanced Materials, vol. 14, pp. 1502-1506, Oct 2002. 

C. Y. Chang, S. Y. Yang, M. S. Wu, L. T. Jiang, and L. A. Wang, "A novel method for fabrication of plastic microlens array with aperture stop>s for projection photolithography," Japanese Journal of Applied Physics Part 1-Regular Papers Brief Communications Review Papers, vol. 46, pp. 2932-2935, May 2007. 

L. Dong and H. Jiang, "Tunable and movable liquid microlens in situ fabricated within microfluidic channels," Applied Physics Letters, vol. 91, p. 041109, Jul 2007. 

P. Nussbaum, R. Volke, H. P. Herzig, M. Eisner, and S. Haselbeck, "Design, fabrication and testing of microlens arrays for sensors and microsystems," Pure and Applied Optics, vol. 6, pp. 617-636, Nov 1997. 

X. Zeng and H. Jiang, "Polydimethylsiloxane microlens arrays fabricated through liquid-phase photopolymerization and molding," Journal of Microelectromechanical Systems, vol. 17, pp. 1210-1217, Oct 2008. 

Microlens arrays fabricated through molding processes Injection-molded plastic lenses... 

Unlike the previous example, a microlens etched by a dry technique on quartz glass is shown in this section. In optical communications, single mode fibers are preferred because of the absence of mode dispersion and mode noise. In order to explore a microlens whose working wavelength lies in the infrared (IR) frequency band (e.g., 1300 nm), Eisner et al. presented silicon microlenses for IR fabricated by reactive ion etching (RIE) [9]. 

Microlens Arrays Fabricated from Self-Assembled Organic Polymers... 

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