Aspheric Surface Measurements – MarSurf FI 2100 AS

Measurements of axially symmetric aspheres, non-axially symmetric asphers, off-axis aspheres, aspheres with slope changing sign, and freeform surfaces

The MarSurf FI 2100 AS Fizeau interferometer provides fast, non-contact, high-resolution measurement of aspheric surfaces. Mahr-ESDI’s patent pending Computer Generated Reference™ (CGR™) technology, combined with sub-Nyquist sampling and traditional phase-shifting interferometry (PSI), provides fast and accurate measurements of aspherical optical components and surfaces without stitching, scanning, null optics, and CGHs.


  • Measures Torics, Biconics, Off-Axis Parabloids, Freeforms, and other surfaces without rotational symmetry
  • No Null lenses, CGHs, axial scanning, or stitching processes required
  • Options for Fully or Semi-Automated Workstations
  • ≥ 1.5mm of departure
  • Automatic Alignment and Measurement in 2 minutes

Data Sheet (PDF)

Overview (PDF)

Setup Guide (PDF)

See It In Action: (may need a few minutes to download with full audio)



The newest generation MarSurf FI 2100 AS is a highly advanced Fizeau interferometer incorporating sub-Nyquist sampling techniques with traditional phase-shifting measurement technologies to accurately measure aspheric surfaces. The MarSurf FI 2100 AS utilizes standard transmission spheres to measure aspheric surfaces. This implies the test and reference beams are no longer common path. However, Mahr-ESDI’s patent pending Computer Generated Reference™ (CGR™) technology performs automatic, non-common path, self calibration by generating a CGR™. The CGR™ is derived from the optical prescription of the interferometric measurement system and the optical prescription of the surface being measured. The CGR™ is in essence how the fringes would appear if the test surface was perfect per its optical prescription. The CGR™ is then combined, in real-time, with actual video fringes. This combination results in the Moire’ effect and allows the creation of nulled interferograms, very similar to those generated from standard spherical surfaces. The system software then utilizes the Moire’ fringes to quickly, accurately, and automatically align the aspheric surface being tested. After data acquisition, the CGR™ is automatically subtracted from the acquired data to give the actual OPD difference relative to the asphere design prescription.