Patent ID: 8830457

Claim:
A method, comprising: (a) generating a linearly polarized source beam; (b) converting the linearly polarized source beam to a circularly polarized source beam, wherein the generating of (a) is performed by a laser, wherein the converting of (b) is performed by a first waveplate; (c) irradiating a first position on a time varying beam reflector with the circularly polarized source beam, wherein the time varying beam reflector is a rotating polygon; (d) directing the circularly polarized source radiation beam from the time varying beam reflector to a telecentric scan lens thereby directing a circularly polarized scanning beam onto a sample; (e) directing a reflected polarized scanning beam onto the time varying beam reflector to produce a stationary polarized reflected beam; (f) converting the stationary polarized reflected beam to a stationary linearly polarized reflected beam; (g) directing a first portion of the stationary linearly polarized reflected beam onto a first detector, wherein the converting of (f) is performed by a second waveplate, and wherein the directing of (g) is performed by a polarizing beam splitter; (h) directing a second portion of the stationary linearly polarized reflected beam onto a second detector, wherein the first portion of the stationary linearly polarized reflected beam is polarized in a first manner, and wherein the second portion of the stationary linearly polarized reflected beam is polarized in a second manner; (i) processing output signals of the first detector to determine the surface slope and the specular reflectivity of a first surface of the sample; and (j) processing output signals of the second detector to determine the surface slope and the specular reflectivity of a second surface of the sample, wherein the processing of (i) and (j) is performed by a processor.