针对自行研制的短波红外平场光谱仪,讨论了波长定标的原理和方法。短波红外平场光谱仪由两个分光探测单元组成,探测单元以平场凹面光栅分光,处于焦平面上的线阵列探测器探测,波长定标分为两个波段进行。为了实现准确的波长定标,针对短波红外平场光谱仪的特点设计了波长定标步骤。双单色仪可以输出光谱仪波长范围内任意波长单色光,选用双单色仪作为光谱定标光源,双单色仪的输出单色光光谱分辨力为1.5 nm,经过光谱仪的分光会聚后成像在线阵列探测器像元上,采用重心法计算出给定波长对应的像元精确位置,通过多项式拟合得出两个探测单元的波长定标系数。定标结果表明,在900～2400 nm波长范围内,定标曲线拟合误差小于0.5 nm,波长定标不确定度优于0.6 nm。

The wavelength calibration methods were investigated for shortwave infrared (SWIR) flat spectroradiometer. The shortwave infrared spectroradiometer includes two measurement units. The unit based on a concave holograph grating, has a flat focal plane along which a photodiode array (PDA) is placed. The wavelength calibration is performed in each respective band. In order to calibrate more accurately, calibration process is designed in accordance with the spectroradiometer characters. For wavelength calibration, the light source of fine spectral line becomes important. We select monochromator as light source which outputs light with spectral resolution of 1.5 nm in shortwave range. In this way, we preliminarily decide which pixel a spectral line is located at. Next, the position of the peak wavelength is determined by the center of gravity method. Then, the coefficients of polynomial curve are decided through data fitting. The calibration results show that in the range of 900～2400 nm the fitting error is less than 0.5 nm and calibration uncertainty better than 0.6 nm.