Convergent beam scanner linearizing method and apparatus
First Claim
1. An apparatus for position encoding in a convergent beam scanned imaging system, comprising:
- gradation means affixed to a reflective surface for providing increments of position of said reflective surface, said reflective surface both rotating and substantially linearly translating in a reference plane that is substantially perpendicular to said reflective surface such that said reflective surface substantially follows a locus of tangents to an ellipse in said reference plane, said ellipse being substantially fixed in said reference plane, said gradation means moving substantially with said reflective surface in said reference plane; and
position encoding means located at a position along said gradation means and substantially fixed in said reference plane for monitoring movement of said gradation means and, thereby monitoring said rotation and said substantially linear translation of said reflective surface, said position encoding means for outputting a signal indicative of said rotation and a portion of said substantially linear translation of said reflective surface, said position optimized such that said signal is substantially linear with respect to an object space angle.
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Accused Products
Abstract
A method of position encoding in convergent beam scanned imaging systems (10) is provided that reduces distortion. Distortion of a scanned image is introduced in convergent beam systems through the application of mirror "pullback" at the limits of the scanning sector, which is required to retain focus over the field of view or scanning sector. The rotational position of a scanner mirror (14) is not proportional to the spatial scanned angle or object space angle (δ) due to this pullback, and thus introduces distortion. Various components of the pullback motion are utilized to provide the compensation required to overcome this distortion. A process is provided that determines the position of a mirror position detector such that the pullback translation motion of the scanner mirror (14) is used to compensate for the nonlinear rotational motion of the scanner mirror (14). This is accomplished by locating the mirror position detector (16) at a predetermined radial distance and angular position with respect to the scanner mirror (14) point of rotation and sensing the rotation of the scanner mirror (14) and pullback. By appropriately selecting the angular position of the mirror position detector (16) with respect to the scanner mirror (14) center of rotation and the direction of pullback, the output of the mirror position detector becomes a substantially linearized representation of the object space angle (δ). Significant reductions in distortion can thus be obtained via optimizing the angular position of the mirror position detector (16) through an iterative mathematical approach performed by a computer.
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Citations
23 Claims
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1. An apparatus for position encoding in a convergent beam scanned imaging system, comprising:
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gradation means affixed to a reflective surface for providing increments of position of said reflective surface, said reflective surface both rotating and substantially linearly translating in a reference plane that is substantially perpendicular to said reflective surface such that said reflective surface substantially follows a locus of tangents to an ellipse in said reference plane, said ellipse being substantially fixed in said reference plane, said gradation means moving substantially with said reflective surface in said reference plane; and position encoding means located at a position along said gradation means and substantially fixed in said reference plane for monitoring movement of said gradation means and, thereby monitoring said rotation and said substantially linear translation of said reflective surface, said position encoding means for outputting a signal indicative of said rotation and a portion of said substantially linear translation of said reflective surface, said position optimized such that said signal is substantially linear with respect to an object space angle. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for position encoding in a convergent beam scanned imaging system, comprising:
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a reticle affixed to a scanner mirror, said scanner mirror comprising a reflective surface, said scanner mirror both rotating and substantially linearly translating in a reference plane that is substantially perpendicular to said reflective surface such that said reflective surface substantially follows a locus of tangents to an ellipse in said reference plane, said ellipse being substantially fixed in said reference plane, said reticle being substantially semicircular in said reference plane and rotating substantially with said scanner mirror; and an encoder located at an angular position along said reticle and substantially fixed in said reference plane, said encoder monitoring rotation of said reticle and, thereby monitoring said rotation and said substantially linear translation of said scanner mirror, said encoder outputting a signal indicative of said rotation and a portion of said substantially linear translation of said scanner mirror, said angular position optimized such that said signal is substantially linear with respect to an object space angle. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A convergent beam scanned imaging system, comprising:
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imaging means for passing an external image; a scanner mirror comprising a reflective surface, said scanner mirror both rotating and substantially linearly translating in a reference plane that is substantially perpendicular to said reflective surface such that said reflective surface substantially follows a locus of tangents to an ellipse in said reference plane, said ellipse being substantially fixed in said reference plane, said external image reflecting from said scanner mirror as a reflected image; a reticle affixed to said scanner mirror, said reticle being substantially semicircular in said reference plane and rotating substantially with said scanner mirror; encoding means located at an angular position along said reticle and substantially fixed in said reference plane for monitoring rotation of said reticle and, thereby monitoring said rotation and said substantially linear translation of said scanner mirror, said encoding means outputting a position signal indicative of said rotation and said substantially linear translation of said scanner mirror, said angular position optimized with an iterative process such that said position signal is substantially linear with respect to an object space angle; detecting means comprising an array of sensors upon which said reflected signal from said scanner mirror impinges for outputting a detected signal representative of said reflected signal; signal processing means for inputting said detected signal and said position signal and correlating said detected signal with said position signal, thereby associating said detected signal with said object space angle. - View Dependent Claims (16, 17, 18, 19)
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20. A method for position encoding in a convergent beam scanned imaging system, comprising:
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grading a reflective surface which provides increments of rotation and translation of said reflective surface, rotating and substantially linearly translating said reflective surface in a reference plane that is substantially perpendicular to said reflective surface such that said reflective surface substantially follows a locus of tangents to an ellipse in said reference plane, said ellipse being substantially fixed in said reference plane; mounting a position encoder which monitors and encodes said rotation and substantially linear translation of said reflective surface at a position about said reflective surface, said position being optimized with respect to linearization of said position signal with respect to an object space angle; and outputting said position signal. - View Dependent Claims (21, 22, 23)
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Specification