2-D straight-scan on imaging surface with a raster polygon
AssigneePrysm, Inc.
InventorsHanxiang Bai, Roger A. Hajjar
Life of this patent
Estimating the term…
Abstract
A 2-D scanning system uses a fast-rotating raster-polygon as a single scanning component to produce straight scan lines over a 2-D image surface. An approach angle of incident light beams to the raster-polygon is selected to minimize pin-cushion distortion of scan lines introduced by polygon scanning on the image surface, and a tilt angle of the rotational axis of the raster-polygon is selected to position said polygon-scanning distortion symmetrically on the image surface. In addition, scan optics are configured to generate a predetermined amount of barrel distortion of scan lines on the image surface to compensate for pin-cushion distortion introduced by polygon scanning.
Claims20
A two-dimensional scanning system, comprising:
- an imaging surface;
- multiple light sources configured to generate multiple light beams, each beam for illuminating a distinct portion of the imaging surface;
- a rotatable raster polygon that has multiple reflective facets and is positioned in an optical path between the multiple light sources and the imaging surface to direct the multiple light beams to the imaging surface with the reflective facets, wherein the reflective facets are each inclined at a different angle with respect to a rotational axis of the rotatable raster polygon;
- and
- a plurality of scan lenses positioned in an optical path between the rotatable raster polygon and the imaging surface and configured to introduce barrel distortion of multiple scan lines that the multiple light beams follow across the imaging surface as the rotatable raster polygon rotates, wherein each scan lens has a convex surface facing an imaging surface;
- wherein the rotational raster polygon is positioned at a tilt angle inclined toward the imaging surface;
- wherein an approach angle of the multiple beams is selected to position a convergence point of the multiple laser beams proximate a reflective facet of the rotatable raster polygon;
- wherein the multiple light beams reflected from a first facet of the rotatable raster polygon is along a first optical path through a first portion of the scan lens at a first incident angle and are incident on the imaging surface at a first vertical position;
- wherein the multiple light beams reflected from a second facet of the rotatable raster polygon is along a second optical path through a second portion of the scan lens at a second incident angle different from the first incident angle and are incident on the imaging surface at a second vertical position different from the first vertical position;
- and
- wherein the magnitude of the approach angle is determined based on a height of the imaging surface, the beam width of an approach beam, and the pupil distance between a raster polygon mirror and a scan optics module.
Dependencies are inferred from the claim text.