Optical System Design of High Throughput Multi-Channel Spectrograph for Very Large Telescope

Hangxin Ji; Yongtian Zhu; Zhongwen Hu

doi:10.3788/AOS201939.0330003

Journals >Acta Optica Sinica >Volume 39 >Issue 3 >Page 0330003 > Article

Acta Optica Sinica
Vol. 39, Issue 3, 0330003 (2019)

Optical System Design of High Throughput Multi-Channel Spectrograph for Very Large Telescope

Hangxin Ji^{1、2、3、*}, Yongtian Zhu^1、2, and Zhongwen Hu^1、2

Author Affiliations

¹ Nanjing Institute of Astronomical Optics & Technology, National Astronomical Observatories, Chinese Academy of Sciences, Nanjing, Jiangsu 210042, China;

² Key Laboratory of Astronomical Optics & Technology, Chinese Academy of Sciences, Nanjing, Jiangsu 210042, China;

³ University of Chinese Academy of Sciences, Beijing 100049, China

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DOI: 10.3788/AOS201939.0330003 Cite this Article Set citation alerts

Hangxin Ji, Yongtian Zhu, Zhongwen Hu. Optical System Design of High Throughput Multi-Channel Spectrograph for Very Large Telescope[J]. Acta Optica Sinica, 2019, 39(3): 0330003 Copy Citation Text

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Fig. 1. Working principle of VPHG

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Fig. 2. Design principle of multi-channel spectrograph

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Fig. 3. Relationship between telescope diameter and camera focal ratio

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Fig. 4. Relationship between different parameters of multi-channel spectrograph. (a) Collimator pupil size and VPHG blazing angle; (b) camera focal ratio and sampling pixel; (c) detector size and number of multi-channel of spectrograph at different camera focal ratios

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Fig. 5. Optical layout of multi-channel spectrograph for 4 m telescope

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Fig. 6. Optical layout of camera system in red channel

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Fig. 7. Spot diagram of spectrograph in red channel

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Fig. 8. Enclosed energy of spot diagram with different wavelengths. (a) 0.695000 μm; (b) 0.850000 μm; (c) 1.000000 μm

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Fig. 9. Theoretical efficiency of multi-channel spectrograph

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Sub-system	Main description
Slit	1″×3'
Collimator	f_coll=1755 mm, F_coll=13
VPHG	Blue:1600mm^-1,20°,350-500 nmGreen:1140mm^-1,20°,490-705 nmRed: 805mm^-1,20°,695-1000 nm
Camera	f_cam=229.5 mm,F_cam=1.7, F_FOV=15°
Detector	4000×2000@15 μm

Table 1. Main parameters of spectrograph with broadband and high throughput for 4 m telescope

Camera	Lens materialin blue channel	Lens materialin green channel	Lens materialin red channel
Lens 1	S-FPL53	S-FPL53	S-FPL53
Lens 2	PBM2Y^**	F4	ZF13^**
Lens 3	S-FPL53	S-FPL53	H-K9L
Lens 4	H-K9L	H-K9L	H-K9L
Lens 5	PBM2Y	H-K9L	S-FPL53
Lens 6	S-FPL51Y	H-K9L	H-K9L
Notes: ^represents the first surface is aspherical; ^*represents the second surface is aspherical.

Table 2. Glass materials and aspherical surface number of camera system in each channel

NO. of lens surface	1	2	3	4	5	6	7	8	9	10	11	12	13	14
1
2	207
3	224	123
4	100	398	316
5	125	438	333	80
6	2901	300	257	218	148
7	141	493	353	108	83	182
8	-538	313	267	237	152	65	111
9	149	538	367	118	97	187	63	157
10	155	591	380	124	104	191	77	166	57
11	175	1659	476	142	119	206	94	211	76	61
12	92	389	311	-52	248	157	125	98	87	76	47
13	163	727	407	132	112	197	87	182	70	50	445	115
14	164	756	411	133	112	198	88	185	71	52	198	123	8
15	166	816	420	135	114	199	89	189	72	55	86	139	18	12

Table 3. Distance between ghost image and detectormm

Hangxin Ji, Yongtian Zhu, Zhongwen Hu. Optical System Design of High Throughput Multi-Channel Spectrograph for Very Large Telescope[J]. Acta Optica Sinica, 2019, 39(3): 0330003

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