Spectroradiometer spectral calibration, ISRF shapes, and related uncertainties

Area of Science:

• Spectroscopy and Radiometry
• Optical Engineering
• Metrology

Background:

• Spectroradiometers are crucial for spectral measurements, with their accuracy dependent on the instrumental spectral response function (ISRF).
• The ISRF's shape is typically modeled as Gaussian, but this assumption may not always accurately represent the true spectral response.
• Uncertainty in ISRF characterization is a primary source of error in laboratory spectral calibration.

Purpose of the Study:

• To investigate the impact of different instrumental spectral response function (ISRF) shapes on spectroradiometer calibration.
• To quantify the uncertainty associated with ISRF assumptions during laboratory spectral calibration.
• To evaluate the performance of various ISRF fitting modes for field spectroradiometers.

Main Methods:

• Spectral calibration of four analytical spectral device field spectroradiometers using multiple ISRF modes.
• Comparison of fitting performance between Gaussian and non-Gaussian ISRF models.
• Uncertainty analysis using Monte Carlo propagation for calibration results.

Main Results:

• The choice of ISRF shape significantly influences calibration accuracy, with non-Gaussian models often providing a better fit.
• The assumption of a Gaussian ISRF can be a major source of uncertainty in laboratory spectral calibration.
• Different ISRF modes exhibit varying fitting performance, highlighting the need for careful selection.

Conclusions:

• Accurate characterization of the instrumental spectral response function (ISRF) is critical for reliable spectroradiometer calibration.
• Moving beyond Gaussian assumptions for ISRF can reduce calibration uncertainty and improve measurement accuracy.
• The study underscores the importance of selecting appropriate ISRF fitting methods for precise spectral data acquisition.