Air-Spaced Vs Solid Etalon

Air-spaced Etalons - Advantages

  • Shorter lead times – hundreds of spacer and plate stock options available ready for assembly
  • Superior thermal stability
  • Mechanically more robust if free spectral range is large
  • Mirrors can be coated simultaneously, resulting in near perfect matching
  • Potentially better effective finesse
  • Can be pressure or tilt tuned

Air-spaced Etalons - Limitations

  • Physically larger
  • Less rugged

Solid Etalons - Advantages

  • More compact
  • Can be temperature tuned
  • More rugged, unless free spectral range value is very high

Solid Etalons - Limitations

  • Poorer thermal stability
  • Practical limit to the thickness
  • Potential for mismatch of reflector coatings
  • Higher defects potential
  • Materials limitations