小型宽波段凹面全息光栅单色仪的优化设计

随着户外物性分析实验的日渐增多,开发轻小型、便携式,且响应波段范围宽的光谱仪器的需求越来越迫切。根据凹面全息光栅均方根优化理论,设计了一款轻小型宽波段单色仪。该单色仪主要由三块IV型凹面全息光栅和上下两层可旋转的平台组成,三块光栅对称地固定于上层平台上,由一台步进电机带动上层平台旋转实现光栅之间的切换,另一台步进电机带动下层平台旋转实现单块光栅的扫描。三块光栅的响应波长范围分别为400～1000,1000～1700和1700～2500nm,其理论分辨极限分别优于2.5,2.8和4.0nm。并对三块光栅的制作误差和双层平台结构误差进行了分析,结果表明,在能够保证的误差范围内,该单色仪的光谱质量可以较好地满足户外光谱分析的要求。

Optimum Design of Miniature Wide-Waveband Concave Holographic Grating Monochromator

The need for developing miniature, portable and wide spectral covering spectrometers is urgent with the increase of field analysis experiment. A miniature wide-waveband monochromator which is comprised of three concave holographic gratings and two flat bedplates are designed based on the root-mean-square merit function. The three concave gratings are fixed on the upper flat bedplate symmetrically which is rotated by a stepper motor to switch the gratings and the other stepper motor is used to rotate the lower flat bedplate to realize the scanning movement. The response wavelength ranges of the three gratings are 400~1000, 1000~1700 and 1700~2500 nm with their corresponding theoretic resolution limit better than 2.5, 2.8 and 4.0 nm respectively. Manufacture errors, fixing errors and errors of the grating-switching flat bedplates are well analyzed for the three gratings. All the results show that within the error bounds the monochromator′s spectral quality can satisfy the demands of the outdoor infrared spectrum analysis very well.