Full-Stokes Polarization Imaging for Application in Astronomy · Isabella Pagano1,2, Jeff Davis1,...
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Background Abstract The polarization of light can provide information about different astronomical objects such as planets and asteroids. This includes knowledge about the grain size of extraterrestrial soil and weaker absorption line spectra that currently cannot be accurately detected. Output of a SBIG camera/polarimeter apparatus was used to determine the capabilities of a division of focal plane (DoFP) polarimeter in capturing polarization signatures of planets and other astronomical objects. [2] There are several types of polarimeters including division of time, amplitude, or aperture. Typically in astronomy, division of time polarimeters are utilized, but these polarimeters require multiple images at slightly different times in order to gather the polarization data. In contrast, a DoFP polarimeter acquires an image in a single shot. Past DoFP polarimeters have implemented an array of linear polarizers and only linear Stokes parameters are calculated. The micropolarizers used in the current DoFP polarimeter detect four different orientations of elliptical polarization allowing for the full-Stokes parameters to be calculated. [3] Images were collected at the 21 and 61 inch Steward Observatory telescopes. Different techniques to align multiple frames of the astronomical objects were explored to achieve a clearer polarization signature using Matlab. Current results suggest that it would be beneficial to continue to test the polarimeter/camera setup. Conclusion Results Methods Robert Sparks (NOAO) , Bob Peterson, Scott Swindell, and Joseph R Hoscheidt Research in Optics (RiO) Grant # 1460723 Dr. John Koshel Melissa Sarmiento Ayala, M.Ed. Steward Observatory Future Work Support References [1] Aime, C. (2006). Direct imaging of exoplanets: Science and techniques : Proceedings of the 200th colloquium of the International Astronomical Union held in Villefranche sur Mer, France, October 3-7, 2005. Cambridge: Cambridge University Press. [2] Jung, M., Kim, S.~S., Min, K.~W., et al.\ 2014, Lunar and Planetary Science Conference, 45, 1315 [3] W. Hsu, G. Myhre, K. Balakrishnan, N. Brock, M. Ibn-Elhaj, and S. Pau, "Full-Stokes imaging polarimeter using an array of elliptical polarizer," Opt. Express 22, 3063-3074 (2014). [4] Y. Shkuratov, V. Kaydash, V. Korokhin, Y. Velikodsky, N. Opanasenko, G. Videen, Optical measurements of the Moon as a tool to study its surface, Planetary and Space Science, Volume 59, Issue 13, October 2011, Pages 1326-1371, ISSN 0032-0633, [5] E. Collett, Field Guide to Polarization, SPIE Press, Bellingham, WA (2005). [6] The Steward Observatory 61'' Kuiper Telescope. (n.d.). Retrieved July 29, 2015. Isabella Pagano 1,2 , Jeff Davis 1 , Chet Maleszewski 1 , Stanley Pau 1 Ideally, micropolarizer measurements form a regular tetrahedron on the Poincare sphere. The micropolarizers detect four different orientations of elliptical polarization. This allows for all of the Stokes vector components to be calculated. Measurement of polarization states forming a regular tetrahedron has a higher signal-to-noise ratio. [3] The micropolarizer has several layers. The system will allow the camera to measure polarization information, and the Matlab code takes this information from the raw data and calculates the Stokes parameters. [3] Raw FITS image of Saturn taken at 61 inch telescope • The images shown display a relatively weak polarization signal. • Saturn is known to have a clear linear polarization signature at the poles which isn’t distinct in this data. [1] • Some images analyzed did not have a high enough intensity to be considered. • Further testing is necessary. • Due to inclement weather telescope time was cut short. • More images could be collected, specifically Jupiter which has a strong polarization signal but there weren’t usable images available for analysis. [1] • Problems with ensuring that the field of view remained stable should be addressed. • Streamlining the image analysis and upgrading the algorithm. 1 University of Arizona, Tucson AZ ; 2 Carnegie Mellon University Full-Stokes Polarization Imaging for Application in Astronomy These are the six basic Stokes parameters. [5] The Poincare Sphere with a regular tetrahedron. {3] Images were taken at the Steward Observatory’s 61 and 21 inch Telescopes with the SBIG camera/polarimeter setup. [6] Stokes Calculation Aligning Stacking Final Image Image Analysis These are the initial unaligned stokes images that haven’t been averaged yet. They display weak signals that don’t appear clearly separated from the noise. S0 S1 DOLP S3 S2 Linear Angle This series of images displays the averaged polarization signals S0 S1 S2 S3 DOLP Linear Angle The S1 polarization signature is between 5-10% for the object captured. S2, S3 and the linear angle data were still weak enough that even with the averaging the signal wasn’t distinct from noise. The DOLP which is a measure of the linear polarization is 15%.
Transcript of Full-Stokes Polarization Imaging for Application in Astronomy · Isabella Pagano1,2, Jeff Davis1,...
Background
Abstract
The polarization of light can provide information about different astronomical objects such as planets and asteroids.This includes knowledge about the grain size of extraterrestrial soil and weaker absorption line spectra thatcurrently cannot be accurately detected. Output of a SBIG camera/polarimeter apparatus was used to determinethe capabilities of a division of focal plane (DoFP) polarimeter in capturing polarization signatures of planets andother astronomical objects.[2] There are several types of polarimeters including division of time, amplitude, oraperture. Typically in astronomy, division of time polarimeters are utilized, but these polarimeters require multipleimages at slightly different times in order to gather the polarization data. In contrast, a DoFP polarimeter acquiresan image in a single shot. Past DoFP polarimeters have implemented an array of linear polarizers and only linearStokes parameters are calculated. The micropolarizers used in the current DoFP polarimeter detect four differentorientations of elliptical polarization allowing for the full-Stokes parameters to be calculated.[3] Images werecollected at the 21 and 61 inch Steward Observatory telescopes. Different techniques to align multiple frames of theastronomical objects were explored to achieve a clearer polarization signature using Matlab. Current results suggestthat it would be beneficial to continue to test the polarimeter/camera setup.
Conclusion
Results
Methods
Robert Sparks (NOAO) , Bob Peterson, Scott Swindell, and Joseph R HoscheidtResearch in Optics (RiO)Grant # 1460723Dr. John KoshelMelissa Sarmiento Ayala, M.Ed.Steward Observatory
Future Work
Support References[1]Aime, C. (2006). Direct imaging of exoplanets: Science and techniques : Proceedings of the 200th colloquium of the International Astronomical Union held in Villefranche sur Mer, France, October 3-7, 2005. Cambridge: Cambridge University Press.[2]Jung, M., Kim, S.~S., Min, K.~W., et al.\ 2014, Lunar and Planetary Science Conference, 45, 1315 [3]W. Hsu, G. Myhre, K. Balakrishnan, N. Brock, M. Ibn-Elhaj, and S. Pau, "Full-Stokes imaging polarimeter using an array of elliptical polarizer," Opt. Express 22, 3063-3074 (2014).[4]Y. Shkuratov, V. Kaydash, V. Korokhin, Y. Velikodsky, N. Opanasenko, G. Videen, Optical measurements of the Moon as a tool to study its surface, Planetary and Space Science, Volume 59, Issue 13, October 2011, Pages 1326-1371, ISSN 0032-0633,[5]E. Collett, Field Guide to Polarization, SPIE Press, Bellingham, WA (2005).[6] The Steward Observatory 61'' Kuiper Telescope. (n.d.). Retrieved July 29, 2015.
Isabella Pagano1,2, Jeff Davis1, Chet Maleszewski1, Stanley Pau1
Ideally, micropolarizer measurements form a regulartetrahedron on the Poincare sphere. Themicropolarizers detect four different orientations ofelliptical polarization. This allows for all of the Stokesvector components to be calculated. Measurement ofpolarization states forming a regular tetrahedron hasa higher signal-to-noise ratio.[3]
The micropolarizer has several layers. The system willallow the camera to measure polarization information,and the Matlab code takes this information from theraw data and calculates the Stokes parameters.[3]
Raw FITS image of Saturntaken at 61 inch telescope
• The images shown display a relatively weak polarization signal.
• Saturn is known to have a clear linear polarization signature at the poles which isn’t distinct in this data.[1]
• Some images analyzed did not have a high enough intensity to be considered.
• Further testing is necessary.
• Due to inclement weather telescope time was cut short. • More images could be collected, specifically Jupiter which
has a strong polarization signal but there weren’t usable images available for analysis.[1]
• Problems with ensuring that the field of view remained stable should be addressed.
• Streamlining the image analysis and upgrading the algorithm.
1University of Arizona, Tucson AZ ; 2Carnegie Mellon University
Full-Stokes Polarization Imaging for Application in Astronomy
These are the six basic Stokes parameters.[5]
The Poincare Sphere with a regular tetrahedron.{3]
Images were taken at the Steward Observatory’s 61 and 21 inch Telescopes with the SBIG camera/polarimeter setup.[6]
Stokes Calculation
Aligning StackingFinal
Image
Image Analysis
These are the initial unaligned stokes images that haven’t been averaged yet. They display weak signals that don’t appear clearly separated from the noise.
S0 S1 DOLPS3S2
Linear Angle This series of images displays the averaged polarization signals
S0S1 S2 S3
DOLP Linear Angle
The S1 polarization signature is between 5-10% for the object captured. S2, S3 and the linear angle data were still weak enough that even with the averaging the signal wasn’t distinct from noise. The DOLP which is a measure of the linear polarization is 15%.
