光谱学与光谱分析, 2020, 40 (3): 837, 网络出版: 2020-03-25  

目标光源差异对阵列式光谱辐射计测量的影响及紫外杂散辐射修正研究

The Effects of Light Source Differences on Array Spectroradiometer Measurements and the Research of Ultraviolet Stray Light Correction
作者单位
中国计量科学研究院光学与激光计量研究所, 北京 100029
摘要
应对气候变化预测与灾害天气防范等科学难题, 空间观测领域提出高精度的光谱辐射度定标需求。 阵列式光谱辐射计存在内部结构缺陷和光学元器件不理想等问题, 导致杂散辐射, 严重影响光谱辐射度测量结果的准确性。 测量多种典型阵列式光谱辐射计的杂散辐射特性, 考虑外场目标光源与实验室定标光源不一致对杂散辐射修正的影响, 分别基于带通滤光片和可调谐激光器研究紫外杂散辐射修正方法。 首先, 利用不同光谱透过率的带通滤光片, 测量可见及红外光谱辐射引起的紫外杂散信号。 针对杂散辐射分布特点, 建立数学修正模型, 实现高效快捷的杂散辐射修正。 地基验证场的光谱辐射亮度测量结果修正后, 紫外杂散辐射信号显著降低。 对于连续分布的宽谱段光源, 带通滤光片修正法具有实验简便易行、 测试过程高效等优点。 然而, 实现非连续分布或窄带光源的高精度杂散辐射修正存在困难。 为此, 建立基于可调谐激光器的杂散辐射测量系统, 解决了各个像素点杂散辐射线扩展函数的测量难题。 改变可调谐激光器的输出波长, 精细化测量各个像素点的杂散辐射线扩展函数, 再推导出杂散辐射信号分布函数, 通过MATLAB软件将矩阵反演运算, 得到各像素点的杂散辐射修正结果, 实现杂散辐射的高精度修正。 利用不同类型的阵列式光谱辐射计验证了该修正方法, 对于非连续分布的窄带光源, 测量结果修正后杂散辐射信号降低了一个数量级, 并且谱线两边的杂散宽峰显著消除, 大幅降低了紫外波段的测量偏差。 针对不同光谱分布的光源, 建立了两种优势互补的杂散辐射修正方法, 有效改善了阵列式光谱辐射计的紫外测量结果偏差, 进一步确保我国地球观测数据的准确性和国际等效互认。
Abstract
With the goal of climate change prediction and disaster weather prevention, high accurate spectral radiance calibration is required in earth observation. Array spectroradiometers have problems such as internal structural defects and unsatisfactory optical components, resulting in stray lights, which seriously affect the spectral radiance measurements. In this paper, the stray lights of various typical array spectroradiometers were measured. The different spectrums of solar radiance and the laboratory calibration lamp were analyzed. Ultraviolet stray light correction methods were studies by using bandpass filters and tunable lasers, respectively. First, bandpass filters with specific transmittances were used to measure ultraviolet stray light signals. The mathematical correction model was established to realize the efficient evaluation and simple correction. The ultraviolet stray light of the solar radiance in ground-based verification site was obviously reduced by using this method. For the continuously distributed wide-spectrum light sources, the correction method with bandpass filter is of simple experimental conditions and efficient work process. However, it is difficult to complete the high accurate stray light correction for the discontinuous distribution or narrow-band light source. Therefore, the stray light measurement system based on tunable laser was established, which can measure the stray light line-spread function of each pixel by changing the output wavelength of the tunable laser, and then the stray light correction results of each pixel are calculated by MATLAB matrix operations. The correction method was verified by different types of array spectroradiometers. For measuring the non-continuously distributed narrow-band source, the stray light signal was reduced by an order of magnitude, and the inter-reflection peaks beside the light source were significantly eliminated. Here, two stray light correction methods with complementary advantages were established for different spectral distribution light sources, which effectively decreased the deviation of the UV measurement results of array spectroradiometers, further ensuring the accuracy of Chinese earth observation data.

李玲, 吴志峰, 王彦飞, 代彩红. 目标光源差异对阵列式光谱辐射计测量的影响及紫外杂散辐射修正研究[J]. 光谱学与光谱分析, 2020, 40(3): 837. LI Ling, WU Zhi-feng, WANG Yan-fei, DAI Cai-hong. The Effects of Light Source Differences on Array Spectroradiometer Measurements and the Research of Ultraviolet Stray Light Correction[J]. Spectroscopy and Spectral Analysis, 2020, 40(3): 837.

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