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US 5,367,399 AGranted
Rotationally symmetric dual reflection optical beam scanner and system using same
AssigneeHolotek Ltd.
InventorCharles J. Kramer
Life of this patent
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AssigneeHolotek Ltd.
InventorCharles J. Kramer
Estimating the term…
A dual reflection unpolarizing monofacet (DRUM) scanner or beam deflector is made up of two essentially identical 45.degree. right angle prism elements with their hypotenuse faces together to form a body which may be rectangular or cylindrical and may be contained in a housing which provides for aerodynamic stability when the scanner rotates at high speed. The hypotenuse faces have a partially reflective surface on which an incident beam, collinear with the rotational axis, is incident. This beam is transmitted and reflected to provide dual beams, one of which is absorbed by light absorbing material, preferably a coating, on a surface of the body and the transmitted beam is retroreflected by a mirror on another surface of the body, back to the partially reflective surface. An output beam is provided by the retroreflected beam. The DRUM deflector may be part of a system which provides a tracking beam of a wavelength different from the scanning beam which is reflected from the partially reflecting surface, then acting as a dichroic beam splitter. A dichroic beam combiner combines light of both wavelengths and directs the light to be incident on the dichroic, partially reflecting surface of the DRUM deflector. A spherical mirror with a clock grating reflects the tracking beam to a photodectector to provide an output signal from which in-scan tracking errors can be derived.
A scanner which scans a light beam which is incident thereon up to 360.degree. about an axis of rotation across a flat field or a cylindrical imaging surface within which the scanner is disposed, said scanner comprising a body rotatable about said axis and having a partially reflecting surface on which said beam is incident and is split into dual beams reflected and transmitted in different directions, a first of which directions is toward said imaging surface and is also transverse to said axis and a second of which directions is away from said imaging surface, a mirror transverse to the path of one of said dual beams, said mirror retroreflects said one of said dual beams, and said retroreflected beam being incident on said partially reflecting surface and projecting therefrom in a direction transverse to said axis to provide an output scanning beam which scans said imaging surface.
A scanner system for providing a first scanning beam of a first wavelength and a second beam of a second wavelength different from said first wavelength which tracks said scanning beam as it scans an image surface to provide a signal indicative of the in-scan tracking error of said system, said system comprising a deflector rotatable about an axis and having a dichroic beam splitter which provides a transmitted beam of said first wavelength, a mirror in the path of said transmitted beam which retroreflects the transmitted beam to said beam splitter where said transmitted beam is reflected transverse to said rotational axis as said first scanning beam, a dichroic beam combiner in the path of light of said first and second wavelengths which directs combined light of said first and second wavelengths to said beam splitter where the light of said second wavelength is reflected as said second beam in a direction opposite to said scanning beam, and means responsive to light of said second wavelength from said second beam for providing said signal.
A scanner which scans a light beam which is incident thereon about an axis of rotation across a flat field or a cylindrical imaging surface within which the scanner is disposed, said scanner comprising a body rotatable about said axis and having a partially reflecting surface on which said beam is incident and is split into dual beams a first of which is reflected and a second of which is transmitted therethrough, said beams extending in differently directed paths one of said paths being generally along said axis and the other of said paths being transverse to said axis, a mirror transverse the path of one of said dual beams, said mirror retroreflects said one of said dual beams towards said partially reflecting surface, said retroreflected beam being incident on said partially reflecting surface and projecting therefrom in a direction transverse to said axis to provide an output scanning beam which scans said imaging surface.
A scanner which scans a light beam which is incident thereon up to 360.degree. about an axis of rotation across a flat field or a cylindrical imaging surface, said scanner comprising a body rotatable about said axis and having a partially reflective surface defining a spatial beam splitter, said beam splitter reflects said incident beam along the path transverse to said axis, or said beam splitter transmits said incident beam along a path generally along said axis, a mirror transverse to the path of said beam which retroreflects said beam in a direction towards said partially reflective surface where said retroreflected beam is transmitted or reflected in a direction towards said imaging surface in a direction transverse to said axis to provide an output scanning beam which scans said imaging surface.
Dependencies are inferred from the claim text.