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Multi-surface optical inspector

  • US 8,830,457 B1
  • Filed: 04/12/2013
  • Issued: 09/09/2014
  • Est. Priority Date: 04/12/2013
  • Status: Active Grant
First Claim
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1. 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.

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