Fizeau Interferometer is one of the simplest and most versatile interferometers and is popular for routine measurements of both flat and spherical surfaces. It is used to measure optical components such as flats, prisms, lenses, or precision metal parts such as bearings, sealing surfaces or polished ceramics. Measurements can be made by using the static fringe analysis software.
The Holmarc Fizeau interferometer (model no:HO-ED-INT-14) basically comes with high optical quality (λ/20) reference flat. The reflection from the test surface interferes with the reflection from reference flat, producing fringes. The shape and quality of the fringes depends on surface quality of the test flat. The fringes are digitalized using a high resolution CCD camera. By analyzing the fringes, we can obtain the P-V flatness, RMS flatness, 3D surface plot etc. The instrument is built upright to fix the test sample easily. The tip /tilt test base allows the test sample to align with the reference surface. High quality aberration corrected optical design enhances performance.
The refractive index of the solid prism using the formula,
n = sin ( (α+β) / 2 ) / sin (α/2)Where α is angle of the prism & β is angle of minimum deviation.
Fig. Basic layout of the Fizeau interferometer