Acta Photonica Sinica, Volume. 52, Issue 5, 0552206(2023)
Optical Design of a High-efficiency Medium-low Dispersion Spectrograph with Wide-band Based on FOSC Type（Invited）
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Fig. 1. The working principle of the double channel spectrograph based on FOSC type
Fig. 3. The optical layout of the double channel multi-mode spectrograph
Fig. 4. The spot diameter of different wavelength at 4 spectral modes in the blue channel
Fig. 5. The spot diameter of different wavelength at 4 spectral modes in the red channel
Fig. 6. Different straight- through grisms，the relationship between spectral resolution and wavelength（left），the relationship between the spectrum position on the CCD in dispersion direction and wavelength（right）
Fig. 7. The spectrograph efficiency curve with different straight-through grisms（GRISM or VPHG）
Fig. 8. The camera design comparison for the red channel of multi-mode astronomical spectrometer
Fig. 9. The spot diameter of different wavelength at 4 spectral modes in the red channel with curved detector
Table 1. The main requirements of the double channel medium-low dispersion spectrograph
View tableView in ArticleTable 1. The main requirements of the double channel medium-low dispersion spectrograph
Technical index Index requirements Working band Blue channel：310~560 nm
Red channel：540~1 000 nm
Spectral resolution R=500，2 000，5 500@0.8″slit Operating temperature -30 ℃~20 ℃ Peak efficiency（without slit loss） ≥40% Minimum efficiency ≥15%（goal） Image quality RMS radius ≤ 10 μm
Table 2. The initial configuration parameters of the spectrograph
View tableView in ArticleTable 2. The initial configuration parameters of the spectrograph
Spectrograph parameter Values Collimator focal length 400 mm Pupil diameter 50 mm Camera focal length 215 mm Camera focal ratio & field of view F/4.3 & φ≥16° CCD 4 K@15 μm Channel working band Blue channel：310~560 nm
Red channel：540~1 000 nm
Table 3. The main parameters of grisms for the blue & red-channel
View tableView in ArticleTable 3. The main parameters of grisms for the blue & red-channel
Resolution mode Line density/（l·mm-1） Groove angle Prism angle & materials Order B-GRISM 500 200 8.95° 10.6° & fused silica 1 B-GRISM 2 000 600 28.7° 33.1° & fused silica 1 B-VPHG 2 000 775 20° 20° & fused silica 1 B-GRISM >5 000 97.11 56° 56° & LF5HTI 9~17 R-GRISM 500 150 10.8° 10.8° & LF5HTI 1 R-GRISM 2 000 300 26.7° 23.5° & LF5HTI 1 R-VPHG 2 000 450 21° 21° & LF5HTI 1 R-GRISM >5 000 91.7 58.9° 58.9° & LF5HTI 5~10
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Hangxin JI, Guoxin BA, Jun LI, Haoran YU. Optical Design of a High-efficiency Medium-low Dispersion Spectrograph with Wide-band Based on FOSC Type（Invited）[J]. Acta Photonica Sinica, 2023, 52(5): 0552206
Paper Information
Category: Special Issue for Advanced Science and Technology of Astronomical Optics
Received: Dec. 27, 2022
Accepted: Feb. 20, 2023
Published Online: Jul. 19, 2023
The Author Email: JI Hangxin (hxji@niaot.ac.cn)
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