Stable multipass Fabry-Perot interferometer: design and analysis

A multipass plane parallel Fabry-Perot interferometer (FPP-M) can give extremely high contrast (in excess of 10(6)) over a wide range of finesse values without reducing the transmission significantly. Curves and tables are provided along with a brief outline of Chabbal's analysis for the residual defects of the Fabry-Perot mirrors to aid a quick assessment of the optimum parameters for a desired spectrometric work. The exploitation of the advantages of an FPP-M depends upon the maintenance of its stability. So, we have constructed a passive interferometer of low thermal expansion material, Cer-Vit, along with nonkinematic design and thermally compensated mirror mounts to achieve long term stability without the use of a servo control device.