Flatness measurement interferometer is used for the inspection of surface flatness of Plano elements such as mirrors, prisms, windows, & Lapped Mechanical Components. We are the only Manufacturer of Laser fizeau interferometer in India.
Principle :
Fizeau interferometer is shown in Figure 1 (The basic layout of a Fizeau Autocollimator). A laser source is spatially filtered via a microscope objective. This microscope objective is located at the focal point of a collimating lens. Between the microscope objective and lens is a cube beam-splitter. The collimated beam encounters a slightly wedged glass plate. This is the heart of the interferometer. The surface adjacent to the collimating lens is of good optical quality. However, the next surface is of exceptional optical quality, λ/10 peak to valley (PV) or better. This is the reference surface and part of the collimated beam is reflected by this surface. Part of the collimated beam continues on to interrogate the optic being tested. The return beam contains information on aberration introduced by the test surface. The two wave fronts recombine inside the interferometer.
The cube beam-splitter diverts the combined beam towards a recording medium, either film or a CCD. An intermediate lens forms an image of the test surface onto the recording plane.
This is a non-contact measurement unlike using Optical Flats by contact. The transmission/reference flat serves as a reference which is compared with the test component. The basic Interferometer has two operating modes: Alignment Mode & View mode. In the Alignment mode, the integral tilt-table is adjusted to superimpose the images on the video monitor. View mode yields high contrast fringes.
From the fringe pattern the flatness of the test component is evaluated.
