Automated high-speed Mueller matrix scatterometer

Abstract

A new scatterometer-polarimeter is described. It measures the angular distribution of intensity and of the complete Mueller matrix of light scattered by rough surfaces and particle suspensions. The measurement time is 1 s/scattering angle in the present configuration but can be reduced to a few milliseconds with modified electronics. The instrument uses polarization modulation and a Fourier analysis of four detected signals to obtain the 16 Mueller matrix elements. This method is particularly well suited to online, real time, industrial process control involving rough surfaces and large particle suspensions (an arithmetic roughness or particle diameter of >1 microm). Some results are given.

Use of polar decomposition for the diagnosis of oral precancer

“…19 In addition, others have shown that polarization-based imaging measurements can provide enhanced visualization of superficial structures 20 -22 to allow for subsurface imaging. 23 The aforementioned applications of polarimetry for biomedical imaging involve the use of Mueller-Stokes calculus to mathematically depict how a biological sample affects the polarization vector of an incident light beam, determined by either backscattered 14,15,24,25 or transmitted 26 -28 light intensities from the sample. The experimental Mueller matrix of a sample contains information on retardance, diattenuation, and depolarization, which is not readily apparent in the original images.…”

Optimal beam splitters for the division-of-amplitude photopolarimeter

“…Several DOAP instruments have been constructed and applied to reflection and scattering Mueller-matrix ellipsometry. [6][7][8][9][10] Because the DOAP generates four linearly independent projections of the unknown Stokes vector of incident light simultaneously (via four independent parallel channels), it is capable of complete and fast (time-resolved) measurement of light polarization or scattering matrices under dynamic conditions.…”

Polarization Sensitive Optical Imaging and Characterization of Soybean Using Stokes-Mueller Matrix Model

“…The polarization state of light after a single scattering event depends on the direction of scattering and incident polarization state. [26][27] In many turbid media such as tissue, scattering structures have a large variance in size and are distributed or oriented in a complex and sometimes apparently random manner. Because each scattering event can modify the incident polarization state differently, until finally the polarization state is completely randomized.…”