Design of a Wide-Band Annular Aperture Optical-Digital Joint Imaging System

Fig. 9. Comparison of degraded images before and after restoration. (a) Original image; (b) degraded image; (c) degraded image with noise; (d) restoration image

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Table 1. Parameters of demand indicators
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Table 1. Parameters of demand indicators
Parameter Value
Track height /km 530
Width of cut /km 37
Ground sampling distance /m ≤15
Spectral range /μm 0.45‒1
Cell size /μm 5.5

Table 2. Design indexes of optical system
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Table 2. Design indexes of optical system
Parameter Value
Effective focal length /mm 185
Effective aperture diameter /mm 46
F number 4
Wavelength /μm 0.45‒1
Field of view /（°） 5
MTF（@90 lp/mm） >0.3

Table 3. Optical system parameters

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Table 3. Optical system parameters

Surface	Type	Radius /mm	Thickness /mm	Glass
Object	Standard	Infinity	Infinity	Air
1	Even Asphere	9999.90	27.00	D-ZLAF67-25
2	Even Asphere	－81.21	－25.80	Mirror
Stop	Even Asphere	－37.85	24.60	Mirror
4	Binary 2	41.28	42.20	Air
Image	Standard	Infinity

Table 4. Even aspheric and diffraction surface coefficients of optical systems

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Table 4. Even aspheric and diffraction surface coefficients of optical systems

Surface	Polynomial coefficient
Surface	$k$	$α_{2}$	$α_{3}$	$α_{4}$	A₁	A₂
1	-5	-9.117×10^-8	1.087×10^-10	-3.856×10^-14	-	-
2	-0.622	1.565×10^-7	4.256×10^-11	-1.131×10^-14	-	-
3	-2.272	6.687×10^-6	-3.556×10^-9	-9.346×10^-12	-	-
4	-	2.964×10^-5	3.522×10^-8	-	-4.896	21.817

Table 5. Results before and after image restoration under different variance values in Gaussian noise

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Table 5. Results before and after image restoration under different variance values in Gaussian noise

Evaluating indicator	Variance value is 0.01		Variance value is 0.001		Variance value is 0.0001
Evaluating indicator	Blurred	Restored	Blurred	Restored	Blurred	Restored
PSNR /dB	17.28	23.69	20.50	27.44	20.83	31.20
SSIM /%	24.48	54.81	64.78	70.86	79.00	85.01

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Shaoying Wang, Shilei Jiang, Jin Zhang, Guobin Sun, Jin Zhao, Weiguo Liu, Xuan Zhou, Xijiang Wei. Design of a Wide-Band Annular Aperture Optical-Digital Joint Imaging System[J]. Laser & Optoelectronics Progress, 2024, 61(4): 0411006

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