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US 4,428,643 AGranted
Optical scanning system with wavelength shift correction
AssigneeXerox Corporation
InventorDavid B. Kay
Life of this patent
Estimating the term…
Abstract
A spot scanning holographic spinner system incorporates an optical element in the optical path to provide compensation for wavelength shifts in the coherent light source. The device is located in a plane parallel to the spinner and consists of a diffraction grating having the same properties as gratings formed on the spinner surface.
Claims7
An optical scanning system including
- a spinner having formed thereon at least one plane linear diffraction grating having a constant grating period d,
- a stationary wavelength compensation diffraction grating having properties identical to said grating formed on said spinner surface, said stationary grating placed in a plane parallel and in optical alignment with said spinner grating,
- a collimated reconstruction light source of wavelength .lambda..sub.r which provides a beam of light directed at an angle of incidence .theta..sub.i onto said compensation grating, said grating diffracting said beam at a diffraction angle of .theta..sub.d,
- said incidence angle .theta..sub.i .perspectiveto..theta..sub.d .perspectiveto.45.degree., and the ratio of .lambda..sub.r to spacing d having a value between 1 and 1.618,
- means for rotating said spinner so that the spinner grating rotates through some rotation angle and diffracts a portion of the incident light at diffraction angle .theta..sub.d, and
- optical means to focus said diffracted beams as a linear scan line on an image plane.
3 more elements
Dependencies are inferred from the claim text.