Dual-sensor arrangment for inspecting slab of material

Abstract

According to an aspect of one or more embodiments, the present subject matter describes an apparatus for inspecting a slab of a material. The apparatus comprises a first and second low-coherence sensor configured to irradiate a first and second side of a slab of material with first light having a first polarization and second light having a second polarization, and thereafter configured to detect a reflection. A first polarizer is configured to allow reflected first light having the first polarization to pass through, and reject a second-light cross-talk portion having the second polarization. A second polarizer is configured to allow reflected second light having the second polarization to pass through, and reject a first-light cross-talk portion having the first polarization. Further, a computing-system is configured to receive signals representing the reflected first light and the reflected second light; and analyze the reflected first light and the reflected second light.

1 . An apparatus for inspecting a slab of a material, the apparatus comprising:
 a computing system configured to analyze light received at a first detector and a second detector;   a first low-coherence sensor configured to:
 receive a first light beam from a first broadband light source; 
 split the first light beam into a first first-beam portion and a second first-beam portion; 
 irradiate a first-side of the slab of material with the first first-beam portion; 
 irradiate a first reflector with the second first-beam portion; 
 receive a first first-beam reflection of the first first-beam portion that reflects off the first side of the slab of material; 
 receive a second first-beam reflection of the second first-beam portion that reflects off the first reflector; 
 combine the first first-beam reflection and the second first-beam reflection into a first combined beam; and 
 direct the first combined beam to the first detector to trigger an analysis of the first combined beam by the computing system; 
   a second low-coherence sensor configured to irradiate with second light a second side of the slab of material that is opposite the first side and detect a reflection therefrom at the second detector to trigger an analysis by the computing system; and   a first polarizer of the first low-coherence sensor, the first polarizer configured to:
 allow light having a first polarization to pass through it; 
 reject light having a second polarization; 
 receive a second-beam cross-talk portion of the second light that passes through the slab of material from the second side to the first side; and 
 reject the second-beam cross-talk portion based on the second-beam cross-talk portion having the second polarization, the rejecting being such that the second-beam cross-talk portion is prevented from being included in the first combined beam.