Wave-front curvature in a Fizeau wavemeter.
The effect of imperfect collimation on the fringe separation of a Fizeau wavemeter is calculated. It is shown that illumination in a plane normal to the wedge face and parallel to the wedge axis enables the detector array to be positioned such that the wavelength error caused by spherical wave-front curvature introduced by the beam expander becomes insignificant to 1 part in 10(8), and no dispersion correction for the wedge plate is required. It is also shown that a sealed air wedge is capable of a wavelength precision approaching 1 part in 10(8).
Gardner
J L
JL