| 摘要 |
An optical alignment system in which an aligning beam of radiation is caused to scan around the periphery of an alignment aperture. Light reflected from the edge of the alignment aperture is collected and a related electrical signal is produced. If the alignment aperture is accurately centered with respect to the motion of the aligning beam, then the electrical signal will be constant. Any lack of centralization will cause variations in the electrical signal. The amplitude and phase of these variations relative to the motion of the aligning beam are indicative of the direction and amount of the decentralization of the alignment aperture with respect to the aligning beam. Hence these parameters are measured and used to operate a servo mechanism which is arranged to move the alignment aperture to centralize it with respect to the aligning beam. The alignment aperture may form part of an optical system, or be attached to a piece of equipment the alignment of which it is desired to maintain.
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