Dynamic noise corrected hyperspectral radiometric calibration in the SWIR range using a supercontinuum laser

Janos C. Keresztes, Ben Aernouts, Richard John Koshel, Wouter Saeys

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

As line scanning short wave infrared (SWIR) hyperspectral imaging (HSI) is a growing field in the food industry, it is important to select efficient illumination designs to image contaminants with high contrast and low noise. Illumination systems can efficiently be compared and optimized through the use of ray tracing simulations. However, these simulations provide illumination patterns in absolute radiometric units while HSI systems typically provide relative measurements. To bridge this gap, a supercontinuum laser and monochromator setup was used in this study to calibrate a SWIR HSI imager in spectral radiometric units. For the radiometric calibration, an integrating sphere (IS) was illuminated with the monochromatic laser light, while both a high sensitivity photodiode and the hyperspectral camera were positioned at different ports of the IS to measure the diffuse light synchronously. For each spectral band, the radiance observed by the imager corresponding to a line was detected using image analysis, while the remainder of the image was used to sample the noise of the sensor. Laser power fluctuations were monitored using a power meter coupled with a thermal sensor, allowing for their correction. As these measurements were time consuming, while InGaAs based sensors are very sensitive to thermal drift, the dark current was sampled frequently to avoid noise time drifts. This approach allowed correcting for 6% of temporal noise fluctuations. A per-pixel linear radiometric model was fitted with an R2 of 0:94±0:3 and used to transfer the measured light distribution of a halogen spot with and without a diffuser into absolute radiometric units. This allowed comparing measurements with the results of ray tracing.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSPIE
Volume9579
ISBN (Print)9781628417456, 9781628417456
DOIs
StatePublished - 2015
Event18th Conference of Novel Optical Systems Design and Optimization - San Diego, United States
Duration: Aug 10 2015Aug 12 2015

Other

Other18th Conference of Novel Optical Systems Design and Optimization
CountryUnited States
CitySan Diego
Period8/10/158/12/15

Keywords

  • Calibration
  • Illumination design
  • infrared lasers
  • integrating sphere
  • Radiometry
  • supercontinuum laser
  • SWIR hyperspectral imaging.

ASJC Scopus subject areas

  • Applied Mathematics
  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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  • Cite this

    Keresztes, J. C., Aernouts, B., Koshel, R. J., & Saeys, W. (2015). Dynamic noise corrected hyperspectral radiometric calibration in the SWIR range using a supercontinuum laser. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 9579). [95790A] SPIE. https://doi.org/10.1117/12.2191101