Single and Double-sided Optical Flats

Advanced Optics manufactures both single and double-surface optical flats which may be used as a reference (test plate) against which the flatness of an unknown surface may be compared or as precision grade or commercial grade optical windows.

• Single-sided flats are typically used as a reference (test plate) and may be made of either Pyrex, fused silica or Zerodur. Surface flatness of 1/4 wave, 1/10 wave or 1/20 wave are available in either fused silica or Zerodur and 1/4 wave and 1/10 wave in Pyrex.
• Double-sided flats may be used either as a reference or as optical windows. Surface flatness of 1/4 wave, 1/10 wave or 1/20 wave are available in either fused silica or Zerodur.

Both single-sided and double sided flats may be purchased either uncoated or with an anti-reflective coating. In addition to their in-stock flats, Advanced Optics offers custom fabrication to meet exact customer requirements.

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Reference Flats

As a reference piece, a single-sided optical flat is placed in contact with a test surface under a monochromatic light. When this is done, an interference pattern of dark and light bands can be seen. The shape of this interference pattern provides an accurate visual representation of the flatness of the test surface. If the interference pattern is curved, the flatness of the test piece is less than that of the reference. However, if the interference pattern is evenly spaced, the flatness of the test piece is equal to or higher than that of the reference flat. An optical flat of greater accuracy than the test piece is required to display a change in the interference pattern.

Optical Windows

Advanced Optics also offers double-sided optical flats for use as optical windows. As with their single-sided optical flats, their windows are made of synthetic fused silica which provides superior transmission characteristics, a high degree of purity, exceptional environmental durability, and a low coefficient of thermal expansion. Advanced Optics dual-surface optical flats are an excellent choice when an optical system requires separation between two environments while passing a specific wavelength(s) of light or for demanding interferometry requirements.

Optical Flat Refinishing

Advanced Optics provides optical flat refinishing services with fast turn-around time. Optical flats and windows become worn and abraded in use and accuracy is lost. This degradation in performance is due to a decrease in the distinctness of the interference pattern, and to a change in the figure caused by scratches on either side of the flat or window. Re-polishing the surface of a piece back to its original accuracy is less costly than replacement.

The accuracy of all our optical flats, whether new or re-polished, are traceable to the National Institute of Standards and Technology and come with a Certificate of Calibration at no extra charge.