Best practices suggest that when coating or setting up an optical component, it’s best to use a witness sample, also called a “test piece,” to ensure that the actual part will match your specific coating specifications and your application.

Sydor Optics also offers witness samples for the measurement of coating stresses on substrates. The size and thickness of a witness sample will typically match your finished product.

  • Test samples available before the commitment of a high-volume run

Available Optical Substrates

Based upon customer demand, Sydor Optics offers Witness Samples made from the following optical substrate materials. Of course, if you don’t see a material you need, please contact a Sales Engineer, who will gladly discuss additional options that may be available.

Coating Witness Sample Manufacturing Limits
Specfications Measurements
Diameter customer specified (typically 25mm – 50mm)
Thickness customer specified (typically 1mm)
Thickness Tolerance ± 0.1mm
Cosmetics (MIL-PRF-13830B) 60-40 to 20-10
Surface Roughness ≥ 5 Ǻ rms
Reflected Wavefront Error (RWE) - before coating ≥ 1/10 wave over clear aperture
Transmitted Wavefront Error (TWE) - before coating ≥ 1/10 wave over clear aperture
Clear Aperture ≤ 95%