The invention discloses a combination
machining method for removing high-frequency errors in optical elements. The combination
machining method includes measuring
surface shape errors of an optical element to be machined by an interferometer, carrying out PSD (power
spectral density) analysis, and determining distribution characteristics of the medium and high-frequency errors on the basis of a DSD curve; acquiring an optimized removal
function model according to predetermined
machining time and machining precision, and acquiring an amplitude
spectral line of a removal function; acquiring
cut-off frequency of the removal function according to the amplitude
spectral line; machining by a
magneto-rheological finishing process if correctable medium and high-frequency errors with the frequency lower than the
cut-off frequency exist according to the frequency distribution of the medium and high-frequency errors; and machining by a computer controlled optical surfacing process if uncorrectable medium and high-frequency errors with the frequency higher than the
cut-off frequency exist according to the frequency distribution of the medium and high-frequency errors. By the combination machining method, technical advantages of MRF (
magneto-rheological finishing) and technical advantages of CCOS (computer controlled optical surfacing) can be sufficiently combined, efficient uniform convergence of all-band errors of the optical element can be realized, and performance of the optical element is effectively improved.