Polarization of Light from Basics to Instruments

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9

circular to linear

analyzer

Part V: ESPaDOnS, circular polarimetry mode

Slide 76

ESPaDOnS: circular polarimetry of (unwanted) linear polarization

half-wave

22.5º positions

gain, transmission

quarter-wave

fixed

linear to elliptical

analyzer

circular part goes through not analyzed and adds same intensities to both beams

linear part is analyzed!

Add a rotating half-wave to “spread out” the unwanted signal

Part V: ESPaDOnS, circular polarimetry mode

Slide 77

ESPaDOnS: linear polarimetry

Half-Wave rhombs positioned at 22.5º increments

Quarter-Wave fixed

Part V: ESPaDOnS, linear polarimetry

Slide 78

ESPaDOnS: linear polarimetry

Half-Wave rhombs positioned as 22.5º increments

First position gives Q

Second position gives U

Switch beams for gain and atmosphere effects

Quarter-Wave fixed

Part V: ESPaDOnS, linear polarimetry

Slide 79

ESPaDOnS - Summary

ESPaDOnS can do linear and circular polarimetry (quarter-wave plate)

Beams are switched around to do the measurements, compensate for gain and atmospheric effects

Fesnel rhombs are very achromatic

Part V: ESPaDOnS, summary

Slide 80

Slide 81

Credits for pictures and movies

Christoph Keller’s home page – his 5 lectures http://www.noao.edu/noao/staff/keller/

“Basic Polarisation techniques and devices”, Meadowlark Optics Inc. http://www.meadowlark.com/

Optics, E. Hecht and Astronomical Polarimetry, J. Tinbergen

Planets, Stars and Nebulae Studied With Photopolarimetry, T. Gehrels

Circular polarization movie http://www.optics.arizona.edu/jcwyant/JoseDiaz/Polarization-Circular.htm

Unpolarized light movie http://www.colorado.edu/physics/2000/polarization/polarizationII.html

Reflection of wave http://www.physicsclassroom.com/mmedia/waves/fix.html

ESPaDOnS web page and documents

Slide 82

References/Further reading On the Web

Very short and quick introduction, no equation http://www.cfht.hawaii.edu/~manset/PolarIntro_eng.html

Easy fun page with Applets, on polarizing filters http://www.colorado.edu/physics/2000/polarization/polarizationI.html

Polarization short course http://www.glenbrook.k12.il.us/gbssci/phys/Class/light/u12l1e.html

“Instrumentation for Astrophysical Spectropolarimetry”, a series of 5 lectures given at the IAC Winter School on Astrophysical Spectropolarimetry, November 2000 –http://www.noao.edu/noao/staff/keller/lectures/index.html