Revercomb H E, Buijs H, Howell H B, Laporte D D, Smith W L, Sromovsky L A
Appl Opt. 1988 Aug 1;27(15):3210-8. doi: 10.1364/AO.27.003210.
A calibrated Fourier transform spectrometer, known as the High-Resolution Interferometer Sounder (HIS), has been flown on the NASA U-2 research aircraft to measure the infrared emission spectrum of the earth. The primary use-atmospheric temperature and humidity sounding-requires high radiometric precision and accuracy (of the order of 0.1 and 1 degrees C, respectively). To meet these requirements, the HIS instrument performs inflight radiometric calibration, using observations of hot and cold blackbody reference sources as the basis for two-point calibrations at each wavenumber. Initially, laboratory tests revealed a calibration problem with brightness temperature errors as large as 15 degrees C between 600 and 900 cm(-1). The symptom of the problem, which occurred in one of the three spectral bands of HIS, was a source-dependent phase response. Minor changes to the calibration equations completely eliminated the anomalous errors. The new analysis properly accounts for the situation in which the phase response for radiance from the instrument itself differs from that for radiance from an external source. The mechanism responsible for the dual phase response of the HIS instrument is identified as emission from the interferometer beam splitter.
一种经过校准的傅里叶变换光谱仪，即高分辨率干涉仪探测仪（HIS），已搭载在美国国家航空航天局（NASA）的U - 2研究飞机上，用于测量地球的红外发射光谱。其主要用途——大气温度和湿度探测——需要高精度的辐射测量精度和准确度（分别约为0.1摄氏度和1摄氏度）。为满足这些要求，HIS仪器进行飞行中的辐射校准，以对热黑体和冷黑体参考源的观测作为每个波数两点校准的基础。最初，实验室测试发现了一个校准问题，在600至900厘米（-1）之间，亮度温度误差高达15摄氏度。该问题出现在HIS的三个光谱带之一中，其症状是与源相关的相位响应。校准方程的微小变化完全消除了异常误差。新的分析正确地考虑了仪器自身辐射的相位响应与外部源辐射的相位响应不同的情况。HIS仪器双相位响应的机制被确定为干涉仪分束器的发射。
