基于准Littrow结构的高动态近红外光谱仪研究

High Dynamic Near Infrared Spectrometer Based on Quasi Littrow Structure

近红外光谱仪是重要的光学分析仪器,具有重要的应用价值。为了实现近红外波段高动态、可调谐分辨率光谱的探测,设置入射狭缝、中间狭缝和出射狭缝,构建了基于准Littrow结构的单光栅双路光谱仪,并利用Zemax软件进行光学系统仿真。在此基础上,研制了实验室用近红外光谱仪,包括光机模块、控制分析模块和探测模块,系统的工作波长为600~1700nm。结果表明:光束以准Littrow角2次经过平面光栅,能有效消除出射光斑的空间色散效应,减小出射光斑的几何尺寸,进而有效抑制光谱信号的边模噪声和降低杂散光强度;光路系统配合自主研制的高动态光电探测系统扩大了获取光谱信号的动态范围;经过光谱标定和相对辐射标定后,利用构建系统对窄带宽激光光源进行探测,系统最高的光谱分辨率(即半峰全宽)优于0.05nm,测得复原激光光谱在中心波长±1nm范围内的动态范围优于70dB。

Near infrared spectrometer is an important optical analytical instrument and has important application.By setting the enter slit,middle slit and exist slit,a spectrometer with a single grating and dual channels based on quasi Littrow structure is built to detect near infrared spectrum with a high dynamic range and tunable resolution.The optical system is simulated by using Zemax software.Then,a near infrared spectrometer with wavelength from600 nm to 1700 nm is set up,and the spectrometer is composed of the optical system,control and analysis system and detection system.The results show that the light passes through the plane grating twice with quasi Littrow angle,the spatial dispersion effect of exit light spot is eliminated and the size of exit light spot is reduced,and then the spectrum edge noise is effectively restrained and the intensity of stray light is reduced.The dynamic range of the spectrum is improved by using the self-developed high dynamic detect system that cooperates with optical system.After spectral calibrating and relative radiation calibrating,the narrow band laser source is detected by using the spectrometer.The highest spectral resolution of the spectrometer,that is full width at half maximum,is better than 0.05 nm,and the dynamic range of the recovery spectrum around the central wavelength with a tolerance of±1 nm is better than70 dB.