UV-Vis-NIR SIRCUS

Example Applications:

• Stray Light Correction of Spectrographs


• Characterization of the Robotic Lunar Observatory (ROLO)


• Calibration of Digital Imaging Systems

Stray Light Correction of Spectrographs

Recently, SIRCUS was used to develop a characterization and correction algorithm for stray light in array spectroradiometers. The algorithm also corrects for fluorescence, a common source of error in UV measurements using integrating spheres.

Figure 1. Schematic diagram of a compact spectrograph

Image of a spectrograph entrance slit on a CCD array.
Figure 2. Image of a spectrograph entrance slit on a CCD detector.		Figure 3. Cross section of the spectrograph shown in Fig. 2, plotted on a logarithmic scale.

Figure 4. Spectral images of laser lines as the laser wavelength was tuned over the spectral coverage of the spectrograph. Y-axis is a logarithmic scale.

Figure 5. Graph of the stray light distribution function, D.

Correction Algorithm

Examples of stray light corrected measurements with Array Spectrometers
Figure 6. Spectral transmittance of green pass-band filter. Red line uncorrected for stray light; Green line, stray light corrected spectrum.		Figure 7. Spectrum from a spectrograph with an integrating sphere fore-optic. Purple line (top), uncorrected spectrum. Blue line (bottom), corrected for stray light, fluorescence and second order diffraction.
Figure 8. Example LED spectra, showing both uncorrected and stray-light-corrected spectra for a blue, green, and red LED (left to right).