Experiment study on large solar telescope mirror seeing

Yan Wang; Yongxing Yang; Jinpeng Li; Yong Bi; Qingsheng Zhu

doi:10.3788/IRLA20230412

Journals >Infrared and Laser Engineering >Volume 53 >Issue 1 >Page 20230412 > Article

Infrared and Laser Engineering
Vol. 53, Issue 1, 20230412 (2024)

Experiment study on large solar telescope mirror seeing

Yan Wang^1,2, Yongxing Yang³, Jinpeng Li^1,2,3, Yong Bi^1,2,3, and Qingsheng Zhu^1,2,3

Author Affiliations

¹Nanjing Research Center of Astronomical Instruments, Chinese Academy of Sciences, Nanjing 210042, China

²University of Science and Technology of China, Hefei 230022, China

³Nanjing Astronomical Instruments Co., Ltd., Chinese Academy of Sciences, Nanjing 210042, China

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DOI: 10.3788/IRLA20230412 Cite this Article

Yan Wang, Yongxing Yang, Jinpeng Li, Yong Bi, Qingsheng Zhu. Experiment study on large solar telescope mirror seeing[J]. Infrared and Laser Engineering, 2024, 53(1): 20230412 Copy Citation Text

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Fig. 1. The laminar state and turbulent state diagram

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Fig. 2. Relationship between FWHM and Strehl Intensity

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Fig. 3. Optical schematic of the mirror seeing experiment

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Fig. 4. Photo of the mirror seeing experiment

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Fig. 5. System overall layout (The hollow circles are SMD temperature sensors and air temperature sensors; the hollow cylinder is the ultrasonic wind direction and speed sensor; the red rectangle is the silicone rubber heating plate; the trapezoid is the electric fan)

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Fig. 6. Temperature sensors curve with time for free convection

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Fig. 7. Test result diagram of ɸ1.55 m large hyperboloid reflector primary mirror

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Fig. 8. Strehl Intensity as a function of mirror-air temperature difference for the 1550 mm mirror (The filled portion of the figure shows the error statistics for multiple sets of experimental data)

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Fig. 9. FWHM as a function of mirror-air temperature difference for the 1550 mm mirror (The filled portion of the figure shows the error statistics for multiple sets of experimental data)

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Fig. 10. Seeing as a function of mirror-air temperature difference for free convection

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$FWHM/\begin{document}$ \Delta {T}_{m} $\end{document} as a function of the Froude number for forced convection$

Fig. 11. FWHM/

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as a function of the Froude number for forced convection

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Species	Parameter
4D interferometer	Diameter: 9 mm; Focal length: 14 mmWorking band: 632.8 nm
Compensating mirror set	Diameter: 82 mm; Material: H-K9LFlat 1 curvature radius: −154.88 mmFlat 2 curvature radius: −325.9 mmDistance between mirrors: −27.506 mm
Large hyperboloid reflector primary mirror	Diameter: 1550 mm; Off-axis distance: 1500 mmMaterial: glass-ceramic; Coating:enhanced aluminum
Flat mirror	Diameter: 1800 mm; RMS: λ/40 (632.8 nm)Material: glass-ceramic

Table 1. Equipment parameter list

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Model	Mirror velocity/m·s⁻¹	$ {\Delta T}_{m} $/℃	$ {r}_{0} $_/cm	Strehl ratio	FWHM/(″)
Free convection	U=0	0	20.67	0.98	0.03
		0.2	12.40	0.97	0.05
		0.5	4.77	0.88	0.13
		0.8	1.94	0.71	0.32
		1	1.48	0.62	0.42
		1.5	1.13	0.51	0.55
		2	0.89	0.40	0.70
		2.5	0.74	0.31	0.84
		3	0.64	0.22	0.97
		3.5	0.55	0.17	1.18
		4	0.43	0.15	1.43

Table 2. Summary of test results for free convection (Mirror velocity=0 m/s)

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Model	Mirror velocity/m·s⁻¹	$ {\Delta T}_{m} $/℃	$ {r}_{0} $/cm	Strehl ratio	FWHM/(″)	$ {F}_{r} $
Forced convection	U=0.2	0	18.51	0.98	0.03	\ 1)
		0.2	15.60	0.97	0.04	0.18
		0.5	8.86	0.92	0.07	0.36
		0.8	2.99	0.78	0.21	0.18
		1	2.18	0.72	0.28	0.22
		1.5	1.75	0.62	0.36	0.40
		2	1.65	0.59	0.38	0.84
		2.5	1.52	0.54	0.41	1.39
		3	1.41	0.50	0.44	1.92

Table 3. Summary of test results for forced convection at low wind speed (Mirror velocity=0.2 m/s) 1) the formula is applicable to

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>0 ℃

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Model	Mirror velocity/m·s⁻¹	$ {\Delta T}_{m} $/℃	$ {r}_{0} $_/cm	Strehl ratio	FWHM/(″)	$ {F}_{r} $
Forced convection	U=1.0	0	15.38	0.94	0.04	\ 1)
		0.2	21.46	0.96	0.03	0.06
		0.5	18.75	0.96	0.03	0.92
		0.8	14.61	0.94	0.04	4.23
		1	12.66	0.91	0.05	2.93
		1.5	4.04	0.89	0.15	6.63
		2	3.07	0.83	0.20	6.77
		2.5	2.64	0.79	0.24	8.84
		3	2.30	0.74	0.27	10.8

Table 4. Summary of test results for forced convection at high wind speed (Mirror velocity=1.0 m/s) 1) the formula is applicable to

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>0 ℃

Yan Wang, Yongxing Yang, Jinpeng Li, Yong Bi, Qingsheng Zhu. Experiment study on large solar telescope mirror seeing[J]. Infrared and Laser Engineering, 2024, 53(1): 20230412

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