Degree of polarization as an objective method of estimating scattering

Abstract

A new method of determining objectively the amount of scattered light in an optical system has been developed. It is based on measuring the degree of polarization of the light in images formed after a double pass through the system. A dual apparatus composed of a modified double-pass imaging polarimeter and a wave-front sensor was used to measure polarization properties and aberrations of the system under test. We studied the accuracy of the procedure in a system that included a lanthanum-modified lead zirconate titanate (PLZT) ceramic plate able to generate variable amounts of scattered light as a function of the applied voltage. Changes in the voltage applied to the ceramics plate modified significantly the scattering contribution while hardly altering the wave-front aberration. The degree of polarization was well correlated with the level of scattering in the system as determined by direct-intensity measurements at the tails of the double-pass images. This indicates that this polarimetric parameter provides accurate relative estimates of the amount of scattering generated in a system. The technique can be used in a number of applications, for example, to determine objectively the amount of scattered light in the human eye.

Grading nuclear cataract opacity by densitometry and objective optical analysis

“…Previous studies 21,25 concluded that light scattering is the main cause of optical degradation in eyes with cataract; therefore, the measurement of scattering [26][27][28] should be performed when evaluating the optical quality of cataractous eyes. In these cases, analysis of the aberrations seems to be less accurate than the MTF values measured by a double-pass method.…”

Eye Cataract Simulation Using Polymer Dispersed Liquid Crystal Scattering Obstacles

“…In previous studies Bueno et al have proposed the loss of the light polarization as a criterion to evaluate the early eye cataract development [7]. Such criterion is an objective and easy achievable one in the model conditions, however using this way in vivo diagnostics for human eye needs applying a complicated ellipsometric double-pass measuring technique [8].…”

GDx-MM: An Imaging Mueller Matrix Retinal Polarimeter

“…In camera-based polarimetry methods, polarized light is delivered over the desired ocular region, and the return light from that region is analyzed and imaged by a camera (Figure 2.9). A common configuration is a fixed polarizer in the generator and a rotating retarder and fixed polarizer in the analyzer [20,[31][32][33]. Related comfigurations include a rotating retarder in the generator [34] or use of a liquid crystal variable retarder [35].…”