- SEMI MF1763 - Test Method for Measuring Contrast of a Linear Polarizer
This Standard was technically approved by the Silicon Wafer Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on August 18, 2017. Available at www.semiviews.org and www.semi.org in March 2018; originally published by ASTM International as ASTM F1763; previously published November 2011.
Polarizer contrast is important in polarimetry systems, ellipsometers, optical modulators, shutters, and target signature discrimination based on polarized radiation.
This Test Method covers measurement of polarizer contrast. It provides procedures suitable for use in service evaluation, manufacturing control, or for research and development purposes. They are not recommended for use in acceptance testing until their precision has been evaluated by interlaboratory comparison unless the parties to the test conduct suitable correlation studies.
The procedures in this Test Method are applicable to polarizers that operate in a transmissive mode at near-normal incidence. Angular or translative offset of the transmitted beam is acceptable if the entire transmitted beam power can be measured.
A distinction is made between contrast, which is an intrinsic polarizer property, and extinction, which is a comparison between two polarizers. Use of contrast to characterize polarizers is encouraged because it is an intrinsic property of the polarizer. Use of extinction to characterize polarizers is discouraged because it is an average between two polarizers and not specific to either one.
The polarizer size or aperture is not limited in this Test Method, but the operator must appreciate that the contrast is an average over the beam spot on the polarizer. Contrast measured at one location on the aperture does not necessarily apply to the entire aperture.
Three procedures are described. The first procedure is a direct contrast measurement that requires a linearly polarized light source with high contrast, CL. The second procedure is a comparison with a linearly polarized light source with known CL. The third procedure is an indirect contrast measurement that can use an unpolarized or polarized light source of unknown CL.
Referenced SEMI Standards