Patent ID: 7119762

Claim:
An apparatus for projecting onto a screen means viewable by a plurality of persons a display including alphanumeric images which can be viewed only by selected persons, the apparatus comprising: first laser means emitting a first polarized beam at a first visible wavelength, second laser means emitting a second polarized beam at a second visible wavelength, one of said first and second polarized beam forming alphanumeric images, and said first and second visible wavelengths being sufficiently close that a color difference therebetween cannot be distinguished by the unaided eye, polarizing beam splitting means for combining said first and second beams, the combined beams being emitted in the same direction with orthogonal polarization orientation, liquid crystal display means for displaying a selected alphanumeric image having a first surface for receiving said combined beams and a second surface provided with a polarizing means for outputting only vertically polarized light, and lens means for projecting said light passed through said second surface onto the screen means, wherein the alphanumeric images can be seen only by selected persons wearing a wavelength selective filter adjacent the eyes.