Optical system and components for optical disk reader

Claim 1

An optical reader system, comprising: means for producing a collimated linearly polarized light beam; a beam splitter and partial polarizer plate comprising a flat, optically transparent glass plate having first and second opposite major surfaces, the first surface being uncoated for transmitting a selected one of two orthogonal polarization components and said second surface having a partial polarizer coating for reflecting said second component substantially without depletion and for reflecting said first component with selected depletion, for directing said selected one of two orthogonal polarization components of the polarized beam to a target and reflectively separating the resulting reflected beam from the beam directed to the target, and selectively enhancing the relative intensity of said two orthgonal polarization components reflected from the target; a plate polarization separator assembly comprising first and second flat plates oriented at selected angles, each of the first and second plates having first and second opposite major surfaces along the direction of the incident linearly polarized reflected beam, said first surface of the first plate having a full polarizer coating for reflecting said second polarization component and transmitting said first polarization component therethrough, said plate being oriented at Brewster's angle relative to the linearly polarized reflected beam, and said first surface of the second plate having a high reflector coating for reflecting the first polarization component back through the first plate, to thereby provide separated divergent beams of said first and second polarization components, for separating the linearly polarized reflected beam into said selectively enhanced polarization components; and means for determining the relative intensities of said selectively enhanced polarization components.