Huang Liangkun, Wen Quan, Huang Jian, Yu Fan, Lei Hongjie, Wen Zhiyu
Key Laboratory of Fundamental Science of Micro/Nano-Device and System Technology, Chongqing University, Chongqing 400044, China.
Microsystem Research Center, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China.
Micromachines (Basel). 2020 Apr 10;11(4):393. doi: 10.3390/mi11040393.
This paper presents a miniaturized, broadband near-infrared (NIR) spectrometer with a flame-retardant 4 (FR4)-based scanning micrograte. A 90° off-axis parabolic mirror and a crossed Czerny-Turner structure were used for creating an astigmatism-free optical system design. The optical system of the spectrometer consists of a 90° off-axis parabolic mirror, an FR4-based scanning micrograte, and a two-color indium gallium arsenide (InGaAs) diode with a crossed Czerny-Turner structure optical design. We used a wide exit slit and an off-axis parabolic mirror with a short focal length to improve the signal-to-noise ratio (SNR) of the full spectrum. We enabled a miniaturized design for the spectrometer by utilizing a novel FR4 micrograte for spectral dispersion and spatial scanning. The spectrometer can detect the full near-infrared spectrum while only using a two-color InGaAs diode, and thus, the grating scanning angle of this spectrometer is small when compared to a dual-detector-based spectrometer. In addition, the angle signal can be obtained through an angle sensor, which is integrated into the scanning micrograte. The real-time angle signal is used to form a closed-loop control over the scanning micrograte and calibrate the spectral signal. Finally, a series of tests was performed. The experimental results showed that the spectrometer has a working wavelength range of 800-2500 nm. The resolution is 10 nm at a wavelength range of 800-1650 nm and 15 nm at a wavelength range of 1650-2500 nm. Similarly, the stability of these two wavelength ranges is better than ±1 nm and ±2 nm, respectively. The spectrometer's volume is 80 × 75 × 65 mm and its weight is 0.5 kg. The maximum spectral fluctuation does not exceed 1.5% and the signal-to-noise ratio is 284 after only one instance of averaging.
本文介绍了一种带有基于阻燃4（FR4）的扫描微光栅的小型宽带近红外（NIR）光谱仪。采用90°离轴抛物面镜和交叉的切尔尼-特纳结构来创建无像散光学系统设计。该光谱仪的光学系统由一个90°离轴抛物面镜、一个基于FR4的扫描微光栅以及一个具有交叉切尔尼-特纳结构光学设计的双色铟镓砷（InGaAs）二极管组成。我们使用宽出射狭缝和短焦距离轴抛物面镜来提高全光谱的信噪比（SNR）。通过利用用于光谱色散和空间扫描的新型FR4微光栅，实现了光谱仪的小型化设计。该光谱仪仅使用双色InGaAs二极管就能检测整个近红外光谱，因此，与基于双探测器的光谱仪相比，此光谱仪的光栅扫描角度较小。此外，角度信号可通过集成在扫描微光栅中的角度传感器获得。实时角度信号用于对扫描微光栅进行闭环控制并校准光谱信号。最后进行了一系列测试。实验结果表明，该光谱仪的工作波长范围为800 - 2500 nm。在800 - 1650 nm波长范围内分辨率为10 nm，在1650 - 2500 nm波长范围内分辨率为15 nm。同样，这两个波长范围的稳定性分别优于±1 nm和±2 nm。该光谱仪的体积为80×75×65 mm，重量为0.5 kg。仅经过一次平均后，最大光谱波动不超过1.5%，信噪比为284。
