Precision Interferometer

Product Code: OS-9255A


No study of interferometry should overlook the historical importance of the Michelson interferometer. Yet in the laboratory, the Fabry-Perot and Twyman-Green interferometers can be more important tools; the first for high-resolution spectroscopy, the second for testing and producing optical components with aberrations that can be measured in fractions of a wavelength.

The PASCO Interferometer is a high-precision, movable-mirror interferometer that can be used to perform Michelson, Fabry-Perot and Twyman-Green interferometry. Mirrors are attached with thumbscrews, so it’s easy to set up and change configurations.

The PASCO Interferometer can be ordered in a variety of systems. The OS-9255A Basic Interferometer can be operated in either the Michelson or Fabry-Perot modes. The Complete Interferometer Systems also contain components for the Twyman-Green mode and a vacuum pump for the refractive index of air experiment.

Note: The fitted case will hold all components and accessories except the 5 kg base, which must be stored separately.


  • Stable: The massive (5 kg) base is machined from a single block of aluminum ensuring extremely stable optics.
  • Smooth Mirror Movement: With the taut-band suspension system, there’s no starting or stopping friction and virtually no backlash (less than 0.5 micron).
  • Precise Measurements: Mirror control is extremely fine— one micron per division of the micrometer head. The mirrors and beam-splitter are flat to 1/4 wavelength to ensure uniform interference patterns.
  • Larger Optics: The 3.2 cm (1 1/4″) diameter optics in the PASCO Inter­fer­ome­ter produce larger and sharper interference patterns for better experimental results.
  • Complete: The Basic Interferometer in­cludes everything necessary to perform basic Michelson and Fabry-Perot interferometry.

What’s Included

  • 1 x Machined Base — 5 kg
  • 1 x Three-Point Adjustable Mirror
  • 1 x Mounted Beam-Splitter
  • 1 x Mounted Movable Mirror
  • 2 x Accessory Mounts
  • 1 x Viewing Screen
  • 1 x Diffuser
  • 1 x Double Convex Lens (18 mm)
  • 1 x Compensator Lens
  • 1 x Fitted Case
  • 1 x Instruction Manual

Required Accessories

1x Laser Alignment Bench OS-9172

Requires One Of These

HE-NE Laser SE-9449A
Mini Laser with Bracket OS-8514

Recommended Accessories

Diffuser OS-9120

Parts Available Separately

Double Convex Lens (18 mm) OS-9132

Also Available

Complete Interferometer System OS-9258B

Support Documents

Manual Downloads

Product Manuals for the Precision Interferometer (OS-9255A)

Precision Interferometer Manual (OS-9255A)
(433 KB – .pdf – English)


Precision Interferometer Video

Shows set-up and features