QED Technologies SSI Technology ASI(Q)

SSI Metrology


Aspheric Stitching Interferometer with QIS

QED innovation and ingenuity brings expanded capabilities and versatility to optics metrology. With the ASI(Q), optics manufacturers can measure a wider range of aspheres and freeforms with more accuracy and faster, without relying on dedicated, expensive null-optics.

The ASI(Q) is powered by QIS, the QED Interferometer for Stitching. QIS is designed and engineered by QED Technologies and takes asphere metrology to the next level of performance. QIS is optimized for stitching and allows the user to collect high quality data on parts with high fringe densities, short radii, with better resolution and with less retrace error.



Measure High Departure Aspheres

QIS is a standard offering on the ASI(Q) platform, or available as a field upgrade to existing ASI and SSI-A platforms.

QED Technologies QIS

The ASI(Q) allows users to measure high departure aspheres and freeforms over the full aperture. Contact us if you would like to learn more about the ASI(Q) metrology system.

The ASI(Q) with QIS is: 

  • Full aperture, for deterministic correction of the whole surface
  • Accurate, to achieve tighter optical specifications
  • Flexible, to minimize custom tooling and lead time
  • Automated and easy-to-use
  • Capable of testing aspheres without dedicated nulls

Configure the ASI(Q) that best fits your needs: 

  • Measure planos, spheres, aspheres and freeforms
  • Measure diameters from 300 mm to 550 mm.

The Stitching Advantage

Stitching technology has four major advantages over standard interferometry: 

  1. Larger field of view—you can see more of the surface.
  2. Higher lateral spatial frequencies—you can see a better picture of the surface.
  3. Improved accuracy—automatically calibrates systematic instrument errors
  4. Asphere and freeform measurement capability without null optics

QED Technologies

Measure Smarter. Measure Better.

ASI(Q) Technical Capabilities

Optical glasses, crystals, metals, ceramics, plastics
Surface Finishes
Part Reflectivity
1% - 100% (attenuation filter required)
Part Geometries
Plano, spherical, aspheric, freeform / concave or convex up to full hemisphere (depending on transmission sphere availability)
Max Aspheric Departure *
≤ 1000 waves (0.6 mm) typical, from best-fit-sphere / (≤ 4000 waves (2.5 mm) departure from vertex sphere)
Max Freeform Departure *
≤ 1600 waves (1 mm) typical, from best-fit-sphere
Measurements Performed
Form deviation from nominal prescription / Rc (with accessible cats-eye) / stitching mismatch map / reference wave error

ASI(Q) Product Specifications

Machine Footprint ASI(Q), XR
53” width x 73” depth (1.34 m width x 1.85 m depth)
Machine Footprint ASI(Q), XRC
53” width x 80” depth (1.34 m width x 2.03 m depth)
Machine Height Installed
107.5” height (2.73 m height)
Total Machine Weight
4019 lbs. (1823 kg)
Measurement Method
Subaperture Stitching Interferometry with a Variable Optical Null (VON) device. (VON not available with XR or XRC models.)
Machine Type
11-axis, automated motion control platform (ASI(Q) XR and XRC are 6-axis)
Interferometer Type
QIS (QED Interferometer for Stitching)
Part Fixturing
25 mm diameter hydro-expansion chuck with variable vacuum feed-through (0 to -40 KPa), part holder kit included.
Z-Axis Travel
820 mm
Test Beam Diameter
6 inches (152 mm)
Downward looking
QED.NET control and analysis software
Measurement 300 mm Ø** 480 mm Ø** 550 mm Ø**


Standard Standard Standard


Standard Standard Standard


Option Option Option


Option Option Option

VON (Variable Optical Null)

Option N/A N/A

QRc Compatibility***

Yes Yes No

Specifications are subject to change without notice.

* Specifications may vary depending on system options and part prescription.

** Gravity sag compensation not included.

*** The QRc radius measurement system from QED Technologies is an optional feature that enables precise measurement of the radius of curvature using a laser displacement measuring interferometer (DMI). The QRc is integrated directly into any QED metrology platform so it operates seamlessly with the QED.NET software. The QRc is available for any QED metrology system using QED.NET software.


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