Metrology Myths: Does your metrology measure up?


Myth #1: Buying additional standard interferometers substantially increases your metrology capabilities.
The Reality: Buying more of the same gives you... more of the same. 30-40% of the optics manufactured today cannot be measured over the full aperture with standard interferometers. SSI  Metrology systems are the only tools that can measure large optics, steep optics and even aspheric optics, with standard transmission elements, over the full aperture.

Myth #2: If a subaperture measurement looks good, the entire part will be in spec.
The Reality: What you see is what you get. A good subaperture measurement truly only indicates the surface of that particular subaperture is good. Even subapertures that cover 70% of the lens surface can give you false confidence in your manufacturing quality. With SSI Metrology systems, you can see the whole surface, every time.

Myth #3: If measurement says it’s good, the part is good.
The Reality: Sometimes the difference between what you WANT to measure and what you are ACTUALLY measuring is significant. Accounting for and correcting transmission element errors is critical but the processes are difficult, slow and are rarely used. SSI  Metrology systems automatically detect and correct systematic errors, including reference wave, distortion, and retrace errors.

Myth #4: Pixel Scale = Resolution
The Reality:  Though the theoretical limit states that features as small as two pixels can be measured, these features are often blurred due to the imaging system and finite aperture of the interferometer. SSI technology can provide the real resolution needed to accurately measure mid and high-spatial frequency features.


Full Aperture Metrology: You no longer need to be satisfied with anything less.

Does your metrology measure up?

  • Are you measuring the full aperture on all your parts?
  • Are you really measuring what you think you are measuring?
  • Are you seeing everything on the surface?
  • Are you measuring aspheres?


SSI Metrology helps you answer all of these questions with confidence.

ASI(Q) systems provide a revolutionary technology. For the first time, it is possible to measure plano, convex, concave, and/or aspheric surfaces up to and exceeding 200 mm in diameter, without expensive investments in large-aperture systems, sophisticated transmission spheres, null lenses or CGHs. You no longer need to be satisfied with anything less than full aperture metrology for virtually all of your optics.