| CPC G01M 11/0214 (2013.01) [G01M 11/04 (2013.01); G02B 5/1857 (2013.01); G02B 7/003 (2013.01); G02B 27/1006 (2013.01); G02B 27/283 (2013.01); G02B 27/30 (2013.01); G02F 1/11 (2013.01)] | 9 Claims |
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1. A plane grating calibration system, comprising an optical subsystem, a frame, a first vibration isolator, a vacuum chuck, a workpiece stage, a second vibration isolator, a base platform and a controller,
wherein the optical subsystem is mounted on the frame, the frame is isolated from vibration by the first vibration isolator, the vacuum chuck is rotatably mounted on the workpiece stage, the workpiece stage is positioned on the base platform, and the base platform is isolated from vibration by the second vibration isolator,
wherein the controller comprises a phase plate,
wherein the optical subsystem comprises a dual-frequency laser, a first beam splitter, a first mirror, a first corner cube mirror, a second corner cube mirror, a first polarizing beam splitter, a phase modulator, a first phase meter, a second polarizing beam splitter, a second mirror, a third mirror, a first collimating lens, a second collimating lens, a first beam sampler, a second beam sampler, a second phase meter, and a displacement interferometer;
wherein the controller is respectively connected with the phase modulator, the first phase meter, the second phase meter and the displacement interferometer; a plane grating to be calibrated is mounted on the vacuum chuck, a dual-frequency orthogonal polarizing laser light emitted by the dual-frequency laser is divided into two beams of dual-frequency orthogonal polarizing laser light transmitted and reflected respectively after passing through the first beam splitter, the transmitted dual-frequency orthogonal polarization laser is split into transmitted light P and reflected light S by the first polarizing beam splitter after being reflected by the first mirror, the transmitted light P sequentially passes through the second mirror, the first collimating lens and the first beam sampler, the light P reflected by the first beam sampler transmits through the second polarizing beam splitter, the light P transmitted through the first beam sampler generates a 0-order diffracted light after passing through the plane grating, and the 0-order diffracted light is reflected by the second beam sampler; the light S reflected by the first polarizing beam splitter sequentially passes through the phase modulator, the third mirror, the second collimating lens and the second beam sampler, the light S reflected by the second beam sampler is reflected by the second polarizing beam splitter and the light P transmitted through the second polarizing beam splitter compose a first measuring light, and the first measuring light is input into the first phase meter; the light S transmitted through the second beam sampler is diffracted by the plane grating to generate a −1-order diffracted light, the −1-order diffracted light is reflected by the second beam sampler and the light P which is the 0-order diffracted light reflected by the second beam sampler compose a second measuring light, and the second measuring light is input into the second phase meter; the orthogonal polarization laser reflected by the first beam splitter is sequentially reflected by the first corner cube mirror and the second corner cube mirror and input into the displacement interferometer to be used for scanning a displacement of the workpiece stage; and
wherein information about the first measuring light obtained by the first phase meter, the second measuring light obtained by the second phase meter and the displacement of the workpiece stage obtained by the displacement interferometer are input into the controller, the dual-frequency laser emits a reference light to the phase plate of the controller, the controller generates a control command through calculating and processing and transmits the control command to the phase modulator, and the phase modulator modulates the laser beam according to the control command to correct an error in the calibration of the plane grating.
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