Design of a multispectral plenoptic camera and its application for pyrometry
Timothy W. Fahringer, Paul M. Danehy, William D. Hutchins, Brian S. Thurow
Abstract
A multispectral imaging system, based on a modified plenoptic camera, is presented. By adding a color filter in the aperture plane of the imaging system, it is possible to simultaneously image multiple discrete colors of light-seven in this design. To develop a measurement system that does not rely on in situ calibrations, each of the optical elements was characterized a priori. For the camera sensor, measurements of the exposure linearity, exposure duration, and quantum efficiency were measured. Additionally, the transmission of the optical filters, both spectral and neutral density, as well as the signal attenuation of the filter holder itself were measured. These measurements result in an instrument that can quantitatively image the emission of seven discrete spectral bands simultaneously. An example application of pyrometry is presented where the emission of a blackbody calibration source with known temperature was imaged. It was determined that by fitting the measured emission at seven wavelengths to Planck's law of radiation, the temperature could be determined to a mean difference of 0.65ºC across five temperatures from 600° to 1000ºC when compared to the set-point temperature.