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9 January 2002 Achromatic waveplate array for polarimetric imaging
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Imaging sensors to detect circular polarization, which have high sensitivity and high frame rates and are light weight and portable, have not been developed. In this paper, we report on our development of novel microscale achromatic retarders. A 2D array of these retarders can be combined with an array of linear polarizers in an imaging sensor. This sensor will be able to capture images of the four Stokes parameters over a wide wavelength band. The achromatic retarder is a combination of two single-order waveplates. Each single-order waveplate is a surface-relief grating. We have calculated the retardance of the combination, using effective medium theory. For light at normal incidence on the achromatic retarder, the retardance is nearly independent of wavelength in the range 3-5 microns and deviates forma mean value of 90 percent by less than 1 percent. We also show that, as field angle is increased, the retardance of our composite retarder deviates less than the retardance of a waveplate formed from a single surface- relief grating. Another advantage of the composite structure is than the achromatic retarder can be fabricated with large aperture on large area substrates.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Cornell S. L. Chun "Achromatic waveplate array for polarimetric imaging", Proc. SPIE 4481, Polarization Analysis and Measurement IV, (9 January 2002);

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