Optical scanning apparatus with dynamic scan path control
First Claim
1. A scanning optical beam system comprising a primary scanning means which produces a scanning optical beam having a scan path close to the desired scan path, a photoresponsive error sensing means which measures over substantially the entire scan path the successive differences transverse to the scan direction between the actual position of the scanning beam and the desired position of the scanning beam and produces error signals, and a secondary scanning means connected to said error sensing means for response to said error signals and operable to dynamically correct the position of the scanning beam transverse to the scan direction during the course of the scan so as to reduce the measured errors.
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Abstract
The system includes a primary scanner which produces a scanning optical beam, and a photoresponsive error sensor which measures over the scan path the successive differences between the actual position of the scanning beam and the desired position of the scanning beam and produces error signals. The secondary scanner is connected to the error sensor for response to the error signals to dynamically correct the position of the scanning beam during the course of the scan. The primary scanner provides a main optical scanning beam and an auxiliary optical scanning beam traversing substantially the same optical path. The error sensor includes a graticule mask having a substantially uniform optical density along the desired scan path and a graded optical density transverse to the desired scan path of the auxiliary scanning beam.
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Citations
32 Claims
- 1. A scanning optical beam system comprising a primary scanning means which produces a scanning optical beam having a scan path close to the desired scan path, a photoresponsive error sensing means which measures over substantially the entire scan path the successive differences transverse to the scan direction between the actual position of the scanning beam and the desired position of the scanning beam and produces error signals, and a secondary scanning means connected to said error sensing means for response to said error signals and operable to dynamically correct the position of the scanning beam transverse to the scan direction during the course of the scan so as to reduce the measured errors.
Specification