A mechanical mosaic method for reflective grating based on diffracted beams orientation

Qihang Zhai; Gaopeng Xue; Liyu Lin; Qian Zhou; Kai Ni; Xiaohao Wang; Xinghui Li

doi:10.1117/12.2602229

9 October 2021 A mechanical mosaic method for reflective grating based on diffracted beams orientation

Qihang Zhai, Gaopeng Xue, Liyu Lin, Qian Zhou, Kai Ni, Xiaohao Wang, Xinghui Li

Proceedings Volume 11898, Holography, Diffractive Optics, and Applications XI; 1189819 (2021) https://doi.org/10.1117/12.2602229
Event: SPIE/COS Photonics Asia, 2021, Nantong, JS, China

Abstract

The planer grating with large area plays an important role in the optical encoder for large stroke measurement. Compared with the conventional fabrication techniques such as interference lithography and mechanically ruling for large-area manufacture, splicing small-area grating units into a large integral mosaic grating is promising to reduce the technical difficulty and time-consumption. We proposed a novel grating splicing method to construct large-area mosaic grating applicable for optical encoder. The splicing apparatus is capable of providing four degree-of-freedom including one outof-plane straight motion (ΔZ) and three rotation motions (Δθ_x, Δθ_y, Δθ_z) for mechanically adjusting the grating units. The diffracted beams from the spliced gratings are utilized to guide the adjustment, i.e., zero-order diffracted beams for ΔZ, Δθ_x, Δθ_y and first-order diffracted beams for Δθ_z, respectively. The diffracted-beams orientations of the first grating were adopted as the basic reference, and the posture of the other gratings are continuously adjusted by matching the position of the diffracted beams. Five grating units with 20×20 mm² area and 1 μm period were spliced together. Finally, a coordinate measuring machine was utilized to evaluate the flatness of the mosaic gratings, showing a good flatness as small as ~60 μm. It is demonstrated that our proposed splicing method is promising to achieve good flatness of mosaic grating potentially applied for large-stroke optical encoder.

Conference Presentation

Citation Download Citation

Qihang Zhai, Gaopeng Xue, Liyu Lin, Qian Zhou, Kai Ni, Xiaohao Wang, and Xinghui Li "A mechanical mosaic method for reflective grating based on diffracted beams orientation", Proc. SPIE 11898, Holography, Diffractive Optics, and Applications XI, 1189819 (9 October 2021); https://doi.org/10.1117/12.2602229

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