Inspecting a slab of material

A system for inspecting a slab of material, the system comprising:

• single mode optical fiber;
• a broadband light source configured to emit light over the optical fiber;
• a beam-forming assembly configured to:
• receive the light over the optical fiber;
• split the light, at a beam splitter, into first and second portions after receiving the light over the optical fiber;
• direct the first portion of the light toward the slab of material;
• direct the second portion of the light onto a reflector that is maintained at a substantially constant distance from the beam splitter;
• combine the first portion of the light after being reflected from the slab of material and the second portion of the light after being reflected from the reflector;
• and direct the combined light over the optical fiber;
• a computer-controlled etalon filter configured to receive the light over the optical fiber either before the light is directed toward the slab of material or after the light has been reflected from or transmitted through the slab of material, filter the light, and direct the light over the optical fiber;
• and a computer-controlled spectrometer configured to receive the light over the optical fiber after the light has been filtered by the etalon filter and after the light has been reflected from or transmitted through the slab of material and spectrally analyze the light.