Patent ID: 9727772
Date: 2017-08-08
CPC Classifications: G02B,G06K,H01L

Claim:
1. A contact image sensor comprising: an illumination source providing a collimated beam of first polarization light; an illuminator waveguide for propagating light in a first TIR path containing a first array of -grating columns; a detector comprising at least one photosensitive element; a platen; a detector waveguide for propagating light in a second total internal reflection (TIR) path containing a second array of grating columns; at least one beam steering grating disposed between said platen and said detector waveguide; a first waveguide coupler for coupling light from said illumination source into said illuminator waveguide; and, a second waveguide coupler for coupling light out of said detector waveguide into an output optical path; wherein each external surface of said detector waveguide is divided into a first grid of strips interspersed with a second grid of strips, said first and second grids having different light-modifying characteristics, overlapping strips from the first grid of strips on each external surface being operative to waveguide light, overlapping strips from the second grid of strips on each external surface being operative to absorb light scattered out of regions of the detector waveguide sandwiched by overlapping strips from the first grid of strips on each external surface, said strips being orthogonal to said grating columns.