AccuFiz Surface Isolation Source

Measure plane-parallel optics without coating the surfaces.

Measure one or both surfaces of a transparent optic. Transmitted wavefront error, optical thickness and homogeneity can be calculated, even on thinner materials.

Fizeau Interferometer - AccuFiz Surface Isolation Source for measuring plane parallel optics

Measure plane-parallel optics

AccuFiz (SIS) – Surface Isolation Source

Plane-parallel optics are transparent components with parallel faces, or systems with two or more parallel surfaces. Measuring any one surface with an interferometer is extremely difficult or impossible, as all parallel surfaces contribute fringes to the interferogram. 

4D’s Surface Isolation Source is an optional, external laser source that excludes all but the surface of interest. The SIS module lets you measure both surfaces of a transparent optic with a standard AccuFiz interferometer. You can also calculate transmitted wavefront error, optical thickness and homogeneity, all from a single measurement setup.

The adjustable path match mechanism provides flexibility, letting you dial in any surface that is within 88 through 112 millimeters from the aperture.

What to expect

With the Surface Isolation Source lets you measure plates or windows with optical thickness as low as 150µm. In a single setup you can measure both the front and back surfaces without repositioning it. Homogeneity, transmitted wavefront error and optical thickness can be readily obtained from a combination of these measurements.

An AccuFiz equipped with SIS can perform all of the functionality of a standard AccuFiz as well as measuring plane-parallel optics. For example, you can use the Surface Isolation Source to measure the flat surface of a plano-convex lens, then switch to the internal source and add a transmission sphere to measure the spherical surface.

An AccuFiz SIS interferometer includes:

  1. AccuFiz 100 mm or 150 mm interferometer
  2. AccuFiz SIS fiber-coupled source module
  3. Advanced software for taking measurements and analyzing the results
  4. Complete computer system
  5. Connecting cables and power supplies.

4Sight™ wavefront analysis software, included with every AccuFiz, features excellent ease of use and a short learning curve. Analyses are included for measuring transmitted wavefront error, optical thickness and homogeneity, as well as measuring the faces and angles of prisms and corner cubes. Comprehensive data sharing capabilities let you read, write, save and print data in many common file formats for comparison between instruments. 


analysis software

Fizeaus and optical production

AccuFiz Fizeaus are well suited to optics manufacturing.

  • Qualify shape and mid-spatial frequencies
  • Measure flats, spheres, cubes and mirrors
  • Wavefront transmission quality measurements
  • Fast and precise
  • Use in Aerospace, Semiconductor and Optics industries

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