Christopher A. Barnett

Micro-optic studies using photopolymers

This paper addresses a set of problems accessible via the technology of photopolymers. Though most interest in micro-optic fabrication centers around the older technology of melted photoresist and the much newer area of binary optics, much can be learned from the area of photopolymers of the graded index type. Recent advances in the technology of the DuPont materials for example, make possible the fabrication of novel micro-optic systems. We examine the manufacture of micro-lens arrays using contact and other forms of lithography. The relative merits of simple refractive optics and graded index optics are discussed. This work has been applied to the formation of specialized diffusion screens for image projection and the advantages are pointed out in the discussion.

Dichromated gelatin--some heretical comments

This paper looks at some ideas old and new that relate to the formation of images in dichromated gelatin. The traditional view that the dichromated system hardens gelatin thus preventing solubilization of the material must be balanced against other observations such as that of the reduction of the bulk index of the gelatin layer and the appearance of gelatin in the processing solutions. We revisit the problem and take a look at some new chemical ideas that relate to the behavior of gelatin during bleaching of silver halides. A new method for the processing of silver halide-sensitized gelatin (S.H.S.G.) is proposed which endows the silver halide emulsion with more than three orders of magnitude of speed when compared with D.C.G. per se.

Experimental techniques for the evaluation of light-induced microlens formation in photopolymers

This paper discusses the formation of GRIN lenses by optical exposure of photopolymer (Du Pont) and the setting up of a simplistic test experiment for evaluation of resulting polymer optical elements. An essential aspect of the work relates to the duration of the exposure. We address the question of differences of performance related to whether the exposure time is greater than or less than the characteristic time scale of monomer diffusion.