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Nonlinearity characterization of array spectroradiometers for the solar UV measurements
Applied Optics
|April 18, 2017
Summary
Two array spectroradiometers showed significant nonlinearity exceeding 10% in solar ultraviolet measurements. Nonlinearities were linked to analog-to-digital converter counts and long integration times, not spectral irradiance levels.
Area of Science:
- Atmospheric Science
- Spectroscopy
- Radiometry
Background:
- Array spectroradiometers offer advantages over scanning types for solar ultraviolet (UV) measurements.
- Accurate solar spectral irradiance measurements demand high instrument linearity.
Purpose of the Study:
- To characterize the nonlinearity of two array spectroradiometers used in solar UV measurements.
- To identify factors contributing to instrument nonlinearity.
Main Methods:
- Characterization of two array spectroradiometers.
- Assessment of nonlinearity as a function of analog-to-digital converter (ADC) counts.
- Evaluation of nonlinearity concerning integration time and spectral irradiance levels.
- Utilized three distinct measurement setups for comprehensive analysis.
Main Results:
- Significant nonlinearities, greater than 10%, were detected as a function of ADC counts.
- Additional nonlinearities were observed at very long integration times.
- No clear residual nonlinearity was found with respect to spectral irradiance across four orders of magnitude.
Conclusions:
- Array spectroradiometers exhibit notable nonlinearities that must be addressed for accurate solar spectral irradiance measurements.
- Nonlinearity is primarily dependent on ADC counts and integration time, rather than the intensity of the measured irradiance.
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