Subaperture stitching allows you to measure a broader range of parts including: bigger clear and numerical aperture surfaces, aspheric surfaces, and system tests.

 

metrology diagram

Advantages of stitching

  1. Aperture Size: increased clear aperture and/or numerical aperture,
  2. Accuracy: automatic calibration of systematic errors,
  3. Resolution: increased detail of edges and mid-spatial frequencies, and
  4. Aspheric Departure: greater aspheric departure in non-null testing.

QED's metrology also helps you to achieve better measurements: have greater confidence in the accuracy, resolution and diagnostics of your measurements to improve your productivity with automation and convenience features The bottom line... QED's subaperture stitching technology produces better measurements on a broader range of parts than any other measurement system.

 

FINALLY: AFFORDABLE FULL APERTURE METROLOGY FOR LARGE AND CONVEX OPTICS IS AVAILABLE.

Even today, optics manufacturers and their customers struggle to cope with serious limitations in conventional interferometry. Our industry is hampered by metrology systems that measure only a subset of all of the optics produced (typically 60-70%). The remaining 30-40% are either too large or too steep to be viewed over the full aperture accurately and affordably. QED's metrology products make it possible to measure almost any plano, convex, or concave surface up to and exceeding 200mm in diameter, without expensive investments in large-aperture systems or sophisticated transmission spheres. You no longer need to be satisfied with anything less than absolute, full aperture metrology for all of your optics.

 

ADDED FLEXIBILITY MEANS GREATER VALUE.

The ASI(Q) overcomes the insufficient coverage of convex and large plano surfaces by providing stitched, full-aperture data with higher absolute accuracy. In addition, for manufacturers that want to reduce cycle times and costs, the ASI(Q) provides rapid and accurate radius of curvature measurements, minimizing the dependence on traditional test plates and radius benches. The ASI(Q) can also be used to acquire higher data density across the full aperture of the part due to its increased lateral resolution. When combined with the ASI(Q), the VON and QIS enable quick, accurate measurements of even extreme aspheric departures.

 

QED's ABSOLUTE METROLOGY OFFERS BETTER QUALITY DATA AND SETS A HIGHER STANDARD.

While transmission elements are commonly accepted as ”perfect”, they are inherently imperfect. Subtraction of the reference wave error can remove these imperfections from the measurement, however, the determination of the reference wave error  is typically a difficult, and time-consuming process, requiring greater operator skill. Instead, the result of a typical interferometric measurement is biased since it includes some reference wave error that is uncharacterized. QED's metrology systems overcome this challenge and provides absolute metrology by automatically computing and removing this reference wave error from each subaperture. Errors of machine motion and geometric distortion are also calculated and accounted for automatically when measuring every surface. After each measurement, a full report is generated, including a full aperture map, the computed reference optic error, and an estimate of the quality of the measurement.