Holographic optical element for compact fingerprint imaging system
Michael H. Metz, Zane A. Coleman, Nicholas J. Phillips, Carl Flatow · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1996
An edge-lit holographic optical element has been developed which produces a high contrast and high resolution fingerprint image. Continuing work on the development of a holographic optical element for use in a compact fingerprint imaging system is described. The hologram is combined with an electronic imaging array into a package only several millimeters thick, using no image transfer lens system. Previously reported results with green holograms are reviewed. New results are presented for red holograms illuminated by a laser diode. Design issues and experimental results are discussed, relating to selection of hologram operating wavelength, angular and wavelength sensitivity of the hologram, and image quality versus packaging volume tradeoffs.