Computer interfaced Fabry-Perot interferometer (Model No:HO-ED-INT-10A) is similar to projection type (model no:HO-ED-INT-10), apart from the fact that in this case, the interference pattern is captured by a CCD sensor and displayed on a computer monitor. The advantage of computer interface is that the pattern can be saved for future analysis. In addition, measurements can be taken directly from the monitor by using the software module provided.
In the etalon, distance between partially reflecting mirrors can be precisely varied in microns. One of the beam splitters can be kinematically adjusted for initial settings.
The wavelength of laser is calculated by,
λ = ( 2d / N ) Δ
The Spacing of the Etalon is given by,
t = nD2λ / χn2
where n is the order, ‘D ’ is the distance between the etalon and the screen, ‘λ’ is the wavelength of light used.
χn2 = χm+n2 - χm2
χm+n2 is the square of the radius of (m+n)th ring and χm2 that of mth ring.
The Free Spectral Range of the Etalon is given by,
FSR = c / 2t,
Where c is the speed of light in air and t is the spacing of the Etalon
The finesse is a measure of the interferometer's ability to resolve closely spaced spectral lines.
The finesse F is defined by the following equation.
F = π √R / ( 1-R )
Where, R is the reflectivity of surfaces