Holographic fingerprint device

A device of compact construction for producing an image of the topographical surface structure of an object, comprising:

• a light transmitting substrate having an index of refraction N1, capable of transmitting light;
• an object illuminating region for illuminating an object in proximity therewith;
• an optical element having an index of refraction N2 and embodying a light-diffractive grating, said optical element being affixed to a portion of said light transmitting substrate, and disposed about an optical axis passing through said object illuminating region;
• and
• light producing means for producing light rays for propagation within said light transmitting substrate, and towards said optical element, said light diffractive grating defining means for redirecting light rays incident thereon to a different optical axis and for propagating the redirected light rays along said different optical axis towards said object;
• whereupon said light rays fall incident upon the object disposed proximate to said object illuminating region, are modulated by the topographical surface structure of the object and propagate back through said light transmitting substrate and said optical element substantially along said different optical axis and fall incident upon an image detection means positionable substantially about said different optical axis, so as to detect an image of the topographical surface structure of the object, wherein the image propagated through said light transmitting substrate and said optical element is along substantially the same optical axis along which light was previously propagated toward the object.