The invention discloses a
double frequency laser grating interference two-dimensional measurement method and
system with optical
aliasing resistance, and belongs to a
grating measurement technology. The
system comprises a
laser device, a
grating interference mirror set and a photoelectric detection and
signal processing unit. Two
laser beams which are simultaneously output by the laser device, different in frequency and separated in space enter a polarizing
beam splitter in parallel and in an incident mode. The first laser beam enters a reference grating in an incident mode after being reflected by the polarizing
beam splitter to form multiple reference
diffraction laser beams with multiple levels, the second laser beam enters a measurement grating in an incident mode after being transmitted by the polarizing
beam splitter to form multiple measurement
diffraction laser beams, three of the reference
diffraction laser beams are sequentially and correspondingly joint with the 0 laser beam, the +1 laser beam and the -1 laser beam in the measurement diffraction laser beams respectively to form an optical beat frequency, and two-dimensional
relative motion information of the measurement grating is acquired through photoelectric detection and
signal processing. By the adoption of the method and
system, optical frequency
aliasing, polarization state
aliasing and corresponding periodic non-linear errors caused by traditional incomplete polarizing
beam splitting are eliminated, and combination properties of a photoetching
machine ultra-precise workpiece table position measurement system can be improved when the
double frequency laser grating interference two-dimensional measurement system is used for the photoetching
machine ultra-precise workpiece table position measurement system.