一般光谱仪的小型化是通过缩小元件尺寸和元件间距离实现的,会降低仪器的性能。为实现高光通量、高光谱分辨率的红外光谱探测,提出一种基于ZnSe平板波导的小型光谱仪的设计方法。说明平板波导结构压缩光束的原理,根据介质中光栅的衍射特性,推导出光谱分辨率与各个参数的关系,给出一个小型光谱仪的具体设计。仪器的光谱范围为8~14μm,光谱分辨率为80nm,数值孔径为O-3,光学系统是一整块ZnSe平板波导,尺寸为70mm×70mm×4mm。并与相同设计指标下一般Czerny—Turner结构的光谱仪进行对比分析。结果表明基于ZnSe平板波导的小型光谱仪系统尺寸更小,光谱分辨率更高,光通量更大。
Common method of spectrometer miniaturization is implemented by decreasing the size of optical components and the distance between them, which will reduce the system performance. In order to achieve high throughput, high spectral resolution infrared spectral detection, a design method of a miniature spectrometer based on ZnSe planar waveguide is proposed. First, the principle of beam compression by planar waveguide is described. Then, in accordance with the diffraction properties of grating in ZnSe medium, the relationship between the spectral resolution and the various optical parameters is deduced. Finally, a specific design of a miniature spectrometer is given. The spectral range of this spectrometer is 8-14μm, the spectral resolution is 80 nm, numerical aperture is 0.3. The optical system is a monolithic ZnSe planar waveguide, the size is 70 mm×70 mm×4 mm. A comparison between this spectrometer and common Czerny-Turner of the same design specifications is done. The results show that miniature spectrometer based ZnSe planar waveguide has very small size, good spectral resolution and high throughput.