PCT No. PCT / US95 / 02155 Sec. 371 Date Dec. 22, 1997 Sec. 102(e) Date Dec. 22, 1997 PCT Filed Feb. 21, 1995 PCT Pub. No. WO95 / 22804 PCT Pub. Date Aug. 24, 1995A method and ultra-compact
system has been developed for illuminating and detecting the surface
topography of an object such as the finger (4) of an individual. The
system (8) is capable of producing high-contrast images which can be electronically transmitted in real-time, or stored using electronic or photographic recording devices. Light traveling within a light transmitting substrate (2) is redirected by a slanted-fringed light diffractive
grating preferably embodied within a
volume hologram (3). The
volume hologram (3), either of the reflection or transmission type, is attached to the light transmitting substrate (2). and functions to diffract light striking thereupon and illuminate an object having topographical
surface structure. After being spatially and intensity modulated in accordance with topographical details of the illuminated object, the insulated light passes back through the light transmitting substrate (2) and the
volume hologram (3), onto an
image detection array. for subsequent analysis. Each of the disclosed embodiments has a compact geometry suitable for use in diverse object identification applications.