The Correction of Keystone Distortion in Czerny–Turner Spectrometer Using Freeform Surface
Guo Xia,
Defeng Yu,
Qingfa Pan,
Qin Pan,
Yanduo Li,
Xiaomeng Chen
Affiliations
Guo Xia
Key Laboratory of Special Display Technology of the Ministry of Education, National Engineering Laboratory of Special Display Technology, National Key Laboratory of Advanced Display Technology, Academy of Photoelectric Technology, Hefei University of Technology, Hefei 230009, China
Defeng Yu
Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, Hefei University of Technology, Hefei 230009, China
Qingfa Pan
Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, Hefei University of Technology, Hefei 230009, China
Qin Pan
Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, Hefei University of Technology, Hefei 230009, China
Yanduo Li
Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, Hefei University of Technology, Hefei 230009, China
Xiaomeng Chen
Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, Hefei University of Technology, Hefei 230009, China
In the past, conventional Czerny–Turner spectrometers were usually designed to achieve high resolution while often ignoring astigmatism in the sagittal direction. In contrast, by replacing the focusing mirror with a freeform surface in the structure, we can obtain a Czerny–Turner spectrometer with low keystone distortion by controlling the astigmatism. At the same time, the area sensor can receive all of the spectrum from the optical system. In this paper, we briefly describe the formation of keystone distortion and smile in a plane grating. Additionally, the validity of the method is verified through simulation. Finally, we evaluated the smile and keystone distortion of both the initial and final systems. The keystone and smile were reduced to 1.77 μm and 8.3 μm, respectively, over the wavelength range of 535 nm to 630 nm. Concurrently, the resolution achieved was 0.4 nm.
