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To address sub-mirror alignment accuracy in large-aperture telescopes, we propose an absolute six-degree-of-freedom grating encoder based on spot position monitoring. This encoder achieves four degrees of freedom (θX, θY, θZ, Z) absolute position and orientation detection using gratings. Additionally, we employ right-angle prisms for absolute position and orientation detection in the X and Y directions, enabling six-degree-of-freedom absolute position and orientation monitoring for sub-mirrors. The monitoring results serve as feedback for sub-mirror pose correction. To mitigate the impact of grating motion on X and Y displacement calculations, we introduce a displacement calculation algorithm based on ray tracing for error compensation, enhancing the accuracy of X and Y displacement calculations and achieving high-precision six-degree-of-freedom measurement and computation. |
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Optical gratings
Diffraction gratings
Phase shifts
Wave equations
Angle measurement
Optical testing
Diffraction
