GRIN lenses

Figure 12.16. Two sampling geometries that use in-line filters near the sample region and graded index (GRIN) lenses. For details, see the text as well as Reference 20.

This method is convenient for fabrication of GRIN lenses, where the required refractive index gradient is obtained by point diffusion [114]. Refractive microlenses with arbitrary geometry may be fabricated by photolithography so that first masks and etching are used to form a mesa or multiple-step structure directly in the substrate, and then additional etching is used (bromine-methanol for HgCdTe or InSb) to round it into a spherical or aspheric surface [115]. 

A design developed by Myrick and Angel (Figure 14A) is based on GRIN lenses (NSG, Tokyo, Japan). Filters are placed in the excitation and... 

CREATING GRADIENT REFRACTIVE INDEX (GRIN) LENSES BY NANOLAYERED... 

Biological GRIN lenses consist of layered assemblies. The human lens has approximately 22,000... 

The polymers used in the fabrication of GRIN lenses were poly(methyl methacrylate) (PMMA) with refractive index of 1.489 (Plexiglas V920 provided by Atofina Chemicals, Inc.), and styrene-acrylonitrile copolymer with 17wt% acrylonitrile (SAN17) with refractive index of 1.573 (Lustran provided by Bayer AG), Table 1. 

A new process to produce bio-inspired GRIN lenses is described. Films of various refractive indices containing thousands of nanolayers with thicknesses below the quarter... 

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