Frequency division splicing interferometer

The invention discloses a frequency division splicing interferometer, which is characterized by comprising a set of multi-dimensional displacement table, a set of attitude adjusting mechanism for a mirror to be measured, an interferometer, two angle measuring devices and a data processing unit, the interferometer, the angle measuring device and the to-be-measured mirror attitude adjusting mechanism are located on the multi-dimensional displacement table; the interferometer is used for acquiring the surface shape of each sub-aperture of the mirror to be measured and sending the surface shape to the data processing unit; the data unit is used for splicing the surface shapes of the sub-apertures of the mirror to be measured to obtain a mirror surface shape h (x, y), performing low-pass filtering on h (x, y), and taking a line satisfying y = y1 in the filtered shape; the first angle measuring device is used for measuring the low-spatial-frequency surface shape slope of the to-be-measured mirror in a translational