Polarimetric calibration of a remote sensor
Described are methods and systems for vicarious polarimetric calibration and performance validation of a remote sensor. The system includes a plurality of reflective mirrors configured and arranged to reflect radiation from a source of radiation onto the remote sensor with accurately known polarimetric properties. Each of the reflective mirrors are located so that the target images do not overlap. The remote sensor is configured to receive the radiation reflected from the plurality of reflective mirrors and store the received radiation as image data (e.g., the image of each mirror appears as a point target). The system includes a processor configured to process the received data to provide direct calibration and performance validation for each polarimetric or spectral channel of the remote sensor. In addition, the calibration method removes all atmospheric effects except for transmittance and provides reference targets that have high polarimetric contrast, full spectrum performance and easy to deploy.
1. A mirror array for polarimetric calibration of a remote sensor, comprising:
a plurality of reflective mirrors configured and arranged to reflect neutral or polarized radiation from a source of radiation onto the remote sensor,
wherein each of the plurality of reflective mirrors having a radius of curvature, the radius of curvature configured to generate reflected light at a known diversity of polarization states and s and p reflectance and control an intensity of the reflected radiation, and
wherein the reflected radiation is utilized to calibrate a remote sensor based on a known at-sensor intensity for each of the plurality of reflective mirrors and subject polarization state of the known diversity of polarization states of the reflected radiation for the respective reflective mirror.
2. The array of claim 1 , wherein one or more of the plurality of reflective mirrors comprise a circular polarization filter/retarder, a linear polarization filter, a polarization orientation filter, or any combination thereof.
3. The array of claim 1 , wherein each of the plurality of reflective mirrors are polarized to a different set of polarization metric values.
4. The array of claim 1 , wherein each of the plurality of reflective mirrors having a radius of curvature, the radius of curvature providing control of an upwelling intensity of the reflected radiation.
5. The array of claim 1 , wherein one or more of the plurality of reflective mirrors are a convex spherical mirror.