Spectroradiometer is used to measure the spectral distribution of radiation sources. It can not only establish the intensity and spectral characteristics of the target or background at the same time but also measure the spectrum and intensity of missile plume and atmospheric transmittance.
The spectroradiometer is generally composed of a collection optical system, spectroscopic components, detectors, and electronic components. Its types include Fourier transform spectroradiometer, multi-detector dispersive prism and grating spectroradiometer, circular graded filter (CVF) low spectral resolution spectroradiometer, and so on.
Several typical working modes of spectroradiometer are as follows:
1) Discrete spectrum measurement mode: the filter wheel stops at a certain position of the filter, and the data is displayed as a function of voltage and time after data acquisition.
2) Continuous spectrum measurement mode: collect data while rotating the filter wheel. These data are displayed as a function of voltage and wavelength.
3) Transmittance measurement mode: work with the external radiation source and optical modulation disc. The radiometer works in non-modulated mode and receives energy from an external modulated radiation source.
CVF or single filter is used for basic data acquisition, and the measured signal is stored in the memory of the instrument as a reference level. In the subsequent data acquisition process, the measured signal level is compared with the signal stored in the memory, and the percentage of the two energies is calculated and displayed on the screen as a function of wavelength as well as time.