4 September 2020 Coma optimization in single spherical collimating lens-based dual-beam exposure system
Vunam Le, Guanhao Wu, Lijiang Zeng
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Abstract

The single collimating lens-based dual-beam exposure system is a holographic exposure system that is suitable for fabricating long-period gratings. The interference wavefront aberration in this system requires optimization. We analyzed the coma of a single collimating lens-based dual-beam exposure system, and the linear relationships between the coma and the positions of the pinholes and substrate are obtained. Based on these relationships, we can eliminate the coma by adjusting the pinholes or substrate along the optical axis of the collimating lens. Consequently, the defocus aberration, astigmatism, low-order spherical aberration, and coma are all simultaneously optimized by adjusting the exposure system to meet the pinhole symmetry condition and coma optimization condition. Because the optimized interference wavefront aberration includes only high-order aberrations with low peak to valley values, a high-quality exposure wavefront can be obtained. Furthermore, a 5-μm period grating exposure system is constructed with a spherical collimating lens of 0.6λ spherical aberration. Through the optimization process, a low spacing error of ∼0.04λ within an aperture of 65  ×  65  mm2 is achieved (the theoretical value is 0.002λ).

© 2020 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2020/$28.00 © 2020 SPIE
Vunam Le, Guanhao Wu, and Lijiang Zeng "Coma optimization in single spherical collimating lens-based dual-beam exposure system," Optical Engineering 59(9), 094103 (4 September 2020). https://doi.org/10.1117/1.OE.59.9.094103
Received: 11 April 2020; Accepted: 24 August 2020; Published: 4 September 2020
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KEYWORDS
Monochromatic aberrations

Wavefront aberrations

Spherical lenses

Wavefronts

Optical engineering

Zernike polynomials

Diffraction gratings

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