Convex blazed grating of high diffraction efficiency fabricated by swing ion-beam etching method.

Area of Science:

• Optics and Photonics
• Spectroscopy
• Materials Science

Background:

• Fabricating convex blazed gratings for hyperspectral imaging spectrometers presents challenges in maintaining consistent blaze angles.
• Conventional translational lithography methods are limited in achieving the required precision for advanced optical components.

Purpose of the Study:

• To present a swing ion-beam etching method for fabricating convex blazed gratings.
• To address the consistency issues of blaze angles in grating fabrication.
• To analyze the performance and applicability of these gratings in shortwave infrared hyperspectral imaging spectrometers.

Main Methods:

• Developed a swing ion-beam etching technique, utilizing meridian direction etching to ensure blaze angle consistency.
• Constructed a geometric model to investigate the impact of swing speed and beam slit width on groove formation.
• Fabricated and characterized convex gratings with specific parameters (45.5 gr/mm, 67 mm aperture, 156.88 mm radius, 2.2° blaze angle).

Main Results:

• Achieved peak diffraction efficiency of 90% and average efficiency of 70% in the shortwave infrared band.
• Demonstrated high groove consistency and small blaze angles.
• Validated the effectiveness of swing etching for producing high-performance gratings.

Conclusions:

• The swing ion-beam etching method successfully produces high-efficiency convex blazed gratings with excellent groove consistency.
• These gratings meet the stringent requirements for high spectral resolution and miniaturization in imaging spectrometers.
• The method offers a viable solution for advanced optical grating fabrication.