PDF(Pubmed)
Abstract：
Hyperspectral detection of the change rate of organic matter content in agricultural remote sensing requires a high signal-to-noise ratio (SNR). However, due to the large number and efficiency limitation of the components, it is difficult to improve the SNR. This study uses high-efficiency convex grating with a diffraction efficiency exceeding 50% across the 360-850 nm range, a back-illuminated Complementary Metal Oxide Semiconductor (CMOS) detector with a 95% efficiency in peak wavelength, and silver-coated mirrors to develop an imaging spectrometer for detecting soil organic matter (SOM). The designed system meets the spectral resolution of 10 nm in the 360-850 nm range and achieves a swath of 100 km and a spatial resolution of 100 m at an orbital height of 648.2 km. This study also uses the basic structure of Offner with fewer components in the design and sets the mirrors of the Offner structure to have the same sphere, which can achieve the rapid adjustment of the co-standard. This study performs a theoretical analysis of the developed Offner imaging spectrometer based on the classical Rowland circular structure, with a 21.8 mm slit length; simulates its capacity for suppressing the +2nd-order diffraction stray light with the filter; and analyzes the imaging quality after meeting the tolerance requirements, which is combined with the surface shape characteristics of the high-efficiency grating. After this test, the grating has a diffraction efficiency above 50%, and the silver-coated mirrors have a reflection value above 95% on average. Finally, the laboratory tests show that the SNR over the waveband exceeds 300 and reaches 800 at 550 nm, which is higher than some current instruments in orbit for soil observation. The proposed imaging spectrometer has a spectral resolution of 10 nm, and its modulation transfer function (MTF) is greater than 0.23 at the Nyquist frequency, making it suitable for remote sensing observation of SOM change rate. The manufacture of such a high-efficiency broadband grating and the development of the proposed instrument with high energy transmission efficiency can provide a feasible technical solution for observing faint targets with a high SNR.
摘要：
农业遥感中有机质含量变化率的高光谱检测需要较高的信噪比(SNR)。然而,由于组件的数量和效率限制，很难提高信噪比。这项研究使用高效率的凸光栅，在360-850nm范围内衍射效率超过50％，具有95%峰值波长效率的背照式互补金属氧化物半导体(CMOS)检测器,和镀银的镜子，以开发用于检测土壤有机质（SOM）的成像光谱仪。设计的系统在360-850nm范围内满足10nm的光谱分辨率，并在648.2km的轨道高度处实现100km的条带和100m的空间分辨率。这项研究还使用了Offner的基本结构，在设计中使用了较少的组件，并将Offner结构的反射镜设置为具有相同的球体，从而可以实现协标准的快速调整。本研究对基于经典Rowland圆形结构开发的Offner成像光谱仪进行了理论分析，21.8mm狭缝长度；模拟其抑制+2级衍射杂散光的能力；并分析满足公差要求后的成像质量，这与高效光栅的表面形状特性相结合。在这个测试之后,光栅的衍射效率高于50%，镀银镜的反射值平均在95%以上。最后,实验室测试表明，该波段的信噪比超过300，在550nm处达到800，高于目前轨道上的一些土壤观测仪器。拟议的成像光谱仪具有10nm的光谱分辨率，在奈奎斯特频率下，其调制传递函数(MTF)大于0.23，适用于SOM变化率的遥感观测。这种高效宽带光栅的制造和所提出的具有高能量传输效率的仪器的开发可以为高信噪比的微弱目标观测提供可行的技术方案。
