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Effect of the number of primary lens level on the MTF of diffractive imaging system
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摘要:
为研究位相型菲涅尔透镜台阶近似引起的衍射杂散光对衍射成像系统调制传递函数(MTF)的影响，本文运用波动光学仿真分析方法模拟光波的传播。通过有限个级次的衍射波面在系统像面上相干叠加，得到系统的点扩散函数(PSF)；对其进行傅里叶变换，得到系统的MTF。以菲涅尔主镜口径为80 mm的衍射成像系统为样机，分析了衍射主镜台阶数目为二、四、八时，系统MTF与理论设计值的差异。结果表明，随着衍射主镜台阶数目的增加，衍射杂散光对系统MTF的影响减小；并且四台阶时，与设计值的偏差已经小于0.5%。最后结合几何光线追迹仿真分析，提出将衍射主镜加工成中心区域多台阶、边缘部分为二台阶的思路，降低了衍射杂散光的影响。
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关键词:
- 衍射成像系统 /
- 二元位相型菲涅尔透镜 /
- 衍射杂散光 /
- 调制传递函数
Abstract:In order to study the effect of diffractive stray light on the modulation transfer function (MTF) caused by the binary phase-type Fresnel lens, the wave propagation method was used to simulate the propagation of light waves. The point spread function (PSF) of the system was obtained by coherent superposition of infinite diffractive orders, and the MTF was obtained by the Fourier transform of the PSF. The differences between the modified values and the theoretical design values were analyzed when the number of level was 2, 4 and 8 at the diffraction imaging system with an 80 mm Fresnel lens as primary lens. The results show that the effect of diffractive stray light on the MTF of the system decreases with the increase of the number of level. However, the deviation from the design value is less than 0.5% when the level is 4. Finally, we put forward the idea that the central region of the lens is processed into several levels and the edge part is 2-level to reduce the effect of diffractive stray light. The results show that the idea can achieve the purpose of suppressing effect of diffractive stray light.
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There is a contradiction between high resolution and light weight of large aperture spaced imaging system. So many research institutions have begun to explore new imaging methods. Diffractive lens through microstructure to modulate light waves can be fabricated on thin films with very low surface mass density. With the benefits of small size, light weight and loose surface tolerance, diffraction imaging system has become a great potential technical solution. Fresnel zone plate (FZP) and photon sieves are the most commonly used microstructures, while the low diffraction efficiency limits the applications of photon sieves. FZP fabricated by binary optics technology can achieve 40.5% diffraction efficiency when the level is 2, and 81% for 4 levels. On the other hand, the diffraction efficiency is a function of the ratio of the design wavelength to the illumination wavelength. Therefore, the non design orders diffractive light may affect the performance of diffractive imaging system and can't be ignored. In order to study the effect of diffractive stray light caused by non design orders on the modulation transfer function of diffractive imaging system, the wave propagation method was used to simulate the propagation of diffractive light waves. By coherent superposition of finite diffractive orders, we calculated the PSF at 17 signal wavelength which evenly covers the spectral range. The sum of these results is the polychromatic PSF. After the point spread function (PSF) of the system was obtained, the Fourier transform of the PSF was done to calculate the modulation transfer function (MTF). The differences between the modified values and the theoretical design values were analyzed when the number of level was 2, 4 and 8 at the diffraction imaging system with an 80 mm Fresnel lens as primary lens. The MTF decreased at low frequency with 2-level Fresnel primary lens and the biggest decrease was 6.6%. The deviation from the design value is less than 0.5% when the level is 4 and 8. The results show that the effect of diffractive stray light on the MTF of the system decreases with the increase of the number of level. Finally, we found that only the incident light illuminating the primary's central area can directly attach the image plane by non design diffractive orders. So, we put forward the idea that the central area of the diffractive primary lens is processed into 4 or 8 levels and the edge part is 2 levels to reduce the effect of diffractive stray light. The MTF increased apparently after optimized and was close to the design value. It shows that the idea can achieve the goal of suppressing the diffractive stray light.
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图 3 样机系统的轴上调制传递函数. (a)二台阶衍射主镜. (b)四台阶衍射主镜. (c)八台阶衍射主镜. (d)最优化衍射主镜.
Figure 3. The on-axis MTF of the prototype. (a) 2-level primary diffractive lens. (b) 4-level primary diffractive lens. (c) 8-level primary diffractive lens. (d) Optimized primary diffractive lens.
表 1 样机系统的基本参数列表.
Table 1. The basic specification of prototype.
Primary lens diameter Effective focal length Field Spectral range Design wavelength 80 mm 361.5 mm ±0.2° 486 nm～656 nm 550 nm 
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表 2 直接到达像面的光通量信息统计.
Table 2. The flux reached on the image of system through different paths.
Path Rays SumFlux Percent/% Split 1 70929 1.41E-01 96.16 +1+1 2 137 3.02E-05 0.02 +1 +3 3 137 2.72E-04 0.19 +1-1 4 121 2.66E-05 0.02 +3+1 5 121 2.40E-04 0.16 -1+1 6 37 8.15E-06 0.01 +1-3 7 29 6.39E-06 0 -3+1 8 3577 8.75E-05 0.06 +3+3 9 2449 4.85E-03 3.32 -1-1 10 673 1.65E-05 0.01 -3-3 11 161 3.55E-05 0.02 -1-3 12 101 2.22E-05 0.02 -3-1 13 37 8.15E-06 0.01 +3-1 14 37 8.15E-06 0.01 -1+3 15 13 3.18E-07 0 -3+3 16 13 3.18E-07 0 +3-3
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[1] Hyde R A. Eyeglass. 1. Very large aperture diffractive tele-scopes[J]. Applied Optics, 1999, 38(19): 4198–4212. doi: 10.1364/AO.38.004198
[2] 张楠, 卢振武, 李凤有.衍射望远镜光学系统设计[J].红外与激光工程, 2007, 36(1): 106–108. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=hwyjggc200701026
Zhang Nan, Lu Zhenwu, Li Fengyou. Optical design of diffractive telescope[J]. Infrared and Laser Engineering, 2007, 36(1): 106–108. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=hwyjggc200701026
[3] 朱威, 徐琰, 颜树华.宽光谱超大孔径反衍望远系统设计[J].应用光学, 2008, 29(1): 40–44. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=yygx200801011
Zhu Wei, Xu Yan, Yan Shuhua. Design of broad bandwidth reflective-diffractive hybrid telescope with super large aperture[J]. Journal of Applied Optics, 2008, 29(1): 40–44. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=yygx200801011
[4] Atcheson P D, Stewart C, Domber J, et al. MOIRE: initial demonstration of a transmissive diffractive membrane optic for large lightweight optical telescopes[J]. Proceedings of SPIE, 2012, 8442: 844221. doi: 10.1117/12.925413
[5] Zhang Zhoufeng, Xie Yongjun, Yin Qinye, et al. Design and testing of infrared diffractive telescope imaging optical systems[J]. Optik, 2015, 126: 5740–5743. doi: 10.1016/j.ijleo.2015.09.079
[6] 王若秋, 张志宇, 国成立, 等.高衍射效率衍射望远镜系统的设计/加工及成像性能测试[J].光子学报, 2017, 46(3): 114–122. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=gzxb201703018&dbname=CJFD&dbcode=CJFQ
Wang Ruoqiu, Zhang Zhiyu, Guo Chengli, et al. Design/fabrication and performance test of a diffractive telescope system with high diffraction efficiency[J]. Acta Photonica Sinica, 2017, 46(3): 114–122. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=gzxb201703018&dbname=CJFD&dbcode=CJFQ
[7] Buralli D A, Morris G M. Effects of diffraction efficiency on the modulation transfer function of diffractive lenses[J]. Applied Optics, 1992, 31(22): 4389–4396. doi: 10.1364/AO.31.004389
[8] Londoño C, Clark P P. Modeling diffraction efficiency effects when designing hybrid diffractive lens systems[J]. Applied Optics, 1992, 31(13): 2248–2252. doi: 10.1364/AO.31.002248
[9] 殷功杰, 薛鸣球.衍射透镜衍射效率及光学传递函数[J].激光技术, 1997, 21(6): 369–371. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=jgjs706.013&dbname=CJFD&dbcode=CJFQ
Yin Gongjie, Xue Mingqiu. Diffractive efficiency of diffractive lenses and its effects on MTF[J]. Laser Technology, 1997, 21(6): 369–371. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=jgjs706.013&dbname=CJFD&dbcode=CJFQ
[10] Simon Thibault, Nathalie Renaud, Min Wang. Effects and prediction of stray light produced by diffractive lenses[J]. Proceedings of SPIE, 1999, 3779: 334–343. doi: 10.1117/12.368224
[11] Zhang Hu, Liu Hua, Lu Zhenwu, et al. Modified phase function model for kinoform lenses[J]. Applied Optics, 2008, 47(22): 4055–4060. doi: 10.1364/AO.47.004055
[12] Yue Jinyin, Liu Hua, Lu Zhenwu, et al. Modified Compound diffractive telescope system: design, stray light analysis, and optical test[J]. Chinese Physics B, 2010(01): 234–240. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=zgwl201001041&dbname=CJFD&dbcode=CJFQ
[13] Breault Research Organization. ASAP technical guide[EB/OL]. (2004-09-08) [2017. 04. 11]. http://www.breault.com.
[14] Swanson G J. Binary optics technology: theoretical limits on the diffraction efficiency of multilevel diffractive optical elements[R]. Lexington, Massachusetts, USA: Lincoln Laboratory, 1991: 5–8.
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