Irradiance measurements via diffusers QVD1 and QVD2, and calibration measurements with the white-light source (WLS) and the LED in the SWIR module (DLED) are used to monitor the stability of the entire instrument and the on-board light sources. All measurements are normalized by taking the ratio with reference measurements from the end of the commissioning phase, when the instrument was stable.
- swir: Ratios of normalized signals as DLED / QVD1, DLED / QVD2, DLED / WLS, WLS / QVD1, WLS / QVD2, QVD1 / QVD2, and background measurements of DLED, QVD1, QVD2, WLS.
- trend: Median of the normalized detector signals of DLED, QVD1, QVD2, WLS as a function of time.