belongs to the dispersive spectrometer, its monochromator is a prism or a grating, which is a single channel measurement, that is, only one narrow band of spectral elements at a time. The spectral distribution of the light source can be measured by turning a prism or a grating and changing its azimuth by point.
With the development of information technology and electronic computer, a new type of infrared spectrometer characterized by multichannel measurement is developed. That is, in a single measurement, the detector can simultaneously detect the information of each spectral element in the light source, for example, in the Harman Transform spectrometer is the grating spectrometer based on the use of a coded template instead of the incident or out of the slit, and then the computer to deal with the signal detected by the detector. Compared with grating spectrometer, the signal-to-noise ratio of Hardman transform spectrometer is higher.