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This paper proposes a fringe locking system consisting of Moiré pattern monitoring via a CCD camera and closed-loop piezoelectric-driven mirror control. To ensure the geometric consistency of the fabricated gratings and the effectiveness of the fringe locking system, an alignment method based on morphological operations and Fast Fourier Transform (FFT) analysis of the image is introduced. Experiments show the proposed system operates at 250 Hz, with significant suppression of low-frequency disturbance components below 100 Hz. The Root-Mean-Square (RMS) value of phase drifts remains below 0.02 fringe periods during the 60-second exposure, laying the foundation for fabricating large optical mosaic gratings. |
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Optical gratings
Diffraction gratings
Optical alignment
Fabrication
Holography
Lithography
Reflection gratings
