Custom optical flat fabricationSydor Optics provides various optical flats – also known as “reference flats,” “test flats” or “test plates” – to meet precision tolerances for the most demanding and exacting applications. An optical flat is manufactured to be extremely flat, and used as a reference for measuring the flatness of other optics with a monochromatic light source or in interferometry applications. Some people also use word “optical flat” or “plano optics” interchangeably with other flat optical components such as optical windows or as substrates for optical mirrors.

As with other products from Sydor Optics, optical flats are fabricated in custom sizes with different coating and beveling options, and can even be polished to include a slight wedge to reduce back reflection. Whether you need λ/4, λ/10, or λ/20 single-sided or double-sided plano optics, Sydor Optics will meet your needs for precision and accuracy.

When it comes to using optical flats for evaluating the flatness accuracy of an unknown optical surface, it’s best to choose a known vendor: Sydor Optics has decades of experience in custom fabrication and resurfacing/refinishing of optical flats.

Plano optics can be accompanied by a protective case and Sydor Optics can also provide supporting documentation and data upon request.

  • High-volume capabilities
  • Custom sizes and beveling options available
  • Diameter up to 400mm
  • Thickness up to 100mm

Available Material Types for Plano Optics

Based upon customer demand, Sydor Optics offers Optical Flats made from the following 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.

Optical Flat Manufacturing Limits
Specifications Measurements
Diameter ≤ 400mm
Thickness ≤ 100mm
Thickness Tolerance ± 0.1mm
Cosmetics (MIL-PRF-13830B) 60-40 to 10-5
Surface Roughness - before coating ≥ 3 Ǻ rms
Reflected Wavefront Error (RWE) - before coating ≥ 1/20 wave over clear aperture
Clear Aperture ≤ 95%
Reusable Protective Packaging available upon request (additional fee)

Types of Plano Optics

Single Surface Optical Flats

Single-sided optical flats are flats that are precision polished on only one side. The other side is left clear, but it is not polished to specification. The polished side of the optical flat may be used to test the flatness of other optical materials such as optical mirrors or wedges. It can also be used as a substrate for optical windows.

Double Surface Optical Flats

Double-sided plano optics are flats that are precision polished to a known flatness on both sides. Because optical flats are used to test the flatness of an unknown surface, either side of a double-sided optical flat can be used for testing, or it could also be used as a substrate for a window.

Optical Flat Coating Options

  • Titanium Dioxide Coating that enhances the fringes

Optical Flat Refinishing / Resurfacing

With careful usage, storage and cleaning an optical flat should provide years of use. However, accidents can happen and normal wear and tear is inevitable. Depending on the type and frequency of usage, the flatness and quality of an optical flat may diminish over time. In certain circumstances, it makes sense to refinish or resurface an optical flat to not only extend its life but also to ensure that your optical flat produces an accurate measurement every time.