Flatness interferometer and how it works

The schematic is the top view of the flatness interferometer apparatus with vertical positioning of a thin transparent wafer (1) and precision optical flat (2). The parabolic metallic reflector (3) creates a beam of monochromatic light from a sodium light source (4). The beam has a uniform distribution of light intensity in the plane of matte glass (5), providing the dispersion of wave vectors of waves within a wide solid angle. The interferometer pattern can be observed visually (7) or taken by camera. The inclined background screen (6), having a diffusive surface, is placed between the light source and the thin transparent wafer.

Flatness Measurement Interferometer Schematic

Flatness Measurement Interferometer

For additional information on the Patented Indars Flatness Interferometer see:

• Fizeau Interferometer limitations
  
• Thin transparent wafer flatness measurements
• Surface flatness measurements with optical flat
• Indars Optical Interferometer

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