The present invention relates to the field of optical detection, and in particular to a spectral
confocal displacement measurement
system based on
heterodyne interference and a measurement method thereof, wherein a
tunable laser emits monochromatic light of different wavelengths, which is divided into two beams of illumination light by a first
beam splitter, one beam of illumination light is incident on a beam combiner after being modulated by a first acousto-optic
frequency shifter, and the other beam of illumination light is incident on a beam combiner after being modulated by a second acousto-optic
frequency shifter, and the two beams of illumination light after being modulated are combined by the beam combiner and incident on a sample
through transmission of a second
beam splitter and focusing of an objective lens to generate
heterodyne interference, forming two light spots with overlapping areas on the sample; the sample reflects the incident
light beam, and the reflected
light beam is then sequentially transmitted by an objective lens, reflected by a second
beam splitter, focused by a third focusing lens, and suppressed by
stray light of a third pinhole, and received by a
photodetector, and converted into an electrical
signal and transmitted to a processor. The present invention can realize the combination of
heterodyne interference technology and spectral
confocal microscopy technology, and improve the measurement resolution.