A method to fabricate convex holographic gratings as master gratings for making flat-field concave gratings

Qian Zhou; Lifeng Li; Lijiang Zeng

doi:10.1117/12.755814

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4 January 2008 A method to fabricate convex holographic gratings as master gratings for making flat-field concave gratings

Qian Zhou, Lifeng Li, Lijiang Zeng

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Proceedings Volume 6832, Holography and Diffractive Optics III; 68320W (2008) https://doi.org/10.1117/12.755814
Event: Photonics Asia 2007, 2007, Beijing, China

Abstract

Ion-beam etching blazed flat-field concave diffraction gratings (FFCG) to achieve high diffraction efficiency is a difficult task. This paper presents a new method to fabricate convex holographic gratings as master gratings for making FFCG. This method makes it convenient to fabricate blazed FFCG with corrected aberrations and uniform predetermined blaze angle over the grating surfaces. It can also be adapted to the commercial fabrication process. This method could be briefly described as follows: First, we make a convex grating using holographic recording method. The grooves are determined by the interference fringes of two spherical waves, one of which is divergent coming from the back side of the substrate, and the other is convergent coming from the front side. Leading-term aberrations can be corrected by optimizing the center positions of the two sphere waves. Second, the exposed convex grating is etched by ion beam to make a blazed convex grating. In this step, it is much easier to get a uniform blaze angle over the surface of a convex grating than over the surface of a concave grating. At last, the etched convex grating is used directly as a master grating to replicate blazed FFCG. An optimized example for a specific system structure is given in this paper. The advantages and difficulties of the method are discussed.

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Qian Zhou, Lifeng Li, and Lijiang Zeng "A method to fabricate convex holographic gratings as master gratings for making flat-field concave gratings", Proc. SPIE 6832, Holography and Diffractive Optics III, 68320W (4 January 2008); https://doi.org/10.1117/12.755814

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