Spectro-Polarimeter Characterization and Control

Basic Overview


  The sun produces unpolarized light which then passes through our atmosphere, and is polarized in a specific way depending on the material it passes through. Our goal is to design an optical front end able to be attached to an ASD spectrometer or Ocean Optics spectrometer. A spectrometer is a device that measures the properties of light over a specific spectrum. Colored light is a blend of different colors which can be seperated into specific wavelengths with different intensities at each wavelength. A spectrometer seperates these colors and determines the strength of each color. Light enters the spectrometer through an optical fiber where the light is then seperated into spectral components and digitized, in terms of wavelength, to be read out on a computer. This optical front end will be mounted on a telescope mount along with the spectrometer, and then pointed at a specific point in the sky. At this specific point, say a cloud, data will be collected at four different polarization states, and the polarization state of light will be characterized according to these measurements. 

System Overview



 An optical front end is required to filter polarized light ranging from visible to short-wave infrared wavelengths. This instrument will accomplish the following level one requirements:


  1. Front end must mount on a telescope mount.
  2. Instrument must be able to measure degree polarization spectra within 1-2% accuracy.
  3. Instrument must be able to be applied to instruments ranging from 400nm to 2500nm.
  4. Demonstration to be performed with instrument out to 1000nm, but optics must support 2500nm.
  5. Instrument must be designed to operate with an ASD Fieldspec and OceanOptics spectrometer.
  6. Desired performance of instrument to measure entire spectrum at once. However, it is acceptable to break measurements into two bands.
  7. Device must be able to be run from a single program in Windows. This includes telescope mount control, ASD Spectrometer Data, Ocean Optics Spectrometer Data, and rotation stage control.



Constraining Instruments


System Overview