Principle of Operation
When a rough surface is examined at a low grazing angle, it appears to be highly reflective. 

The LAZER GRAZER utilizes this principle to produce high contrast interferograms of unpolished surfaces.  A grazing angle of 14.48 degrees was selected since at that angle, each interference fringe equals one wavelength.  With a normal incidence Fizeau Interferometer, each fringe equals one half wavelength. Clicking on the link below will provide further information on the subject of 
Grazing Incidence Interferometers

The original format shown above provides a smaller footprint, but otherwise performs the same as the new low profile model shown at the right.

The low profile, open top model, 2GRPL is designed to facilitate automated test piece positioning. Either model is certain to provide you with the most economical solution to the problem of measuring flatness of unpolished parts.

Low Profile LAZER GRAZER Model 2GRPL

A typical Durango screen, at the left, shows live interferogram, histogram, and OPD plot. Durango permits the user to select from a wide array of graphics, text files and customized reports. 

Note that the live image shows interference fringes on the surface of the test sample while providing a 3-D image of the part. This is a unique display is a feature available only with GRAHAM's Grazing Incidence Interferometers!  This capability is of enormous value in the interpretation of test pieces with complex geometry.