Dioptrate focus shifting type confocal microscopic differential measuring method and device

The invention relates to a dioptrate focus shifting type confocal microscopic differential measuring method and device, and belongs to the field of ultra-precise measuring and three-dimensional imaging. The device solves the problems that a commonly-used differential confocal system based on polarization splitting prism light splitting is low in integration level, and the detection synchronicity of two pinhole detectors is difficult to guarantee. The device mainly comprises a linear polarization light source system, a prismatic decomposition measuring system and a dioptrate phase filter confocal detection system; according to the device, two completely same measuring light beams are separated from a one-dimensional phase grating, light intensity response axial positive translation and negative translation are achieved by means of different optical pupil areas of a dioptrate phase optical pupil filter, and synchronous collection is achieved through a CCD camera. According to the scheme, positive focus shifting and negative focus shifting of two paths of measuring light beams are achieved simultaneously according to a focus shifting effect principle of the phase optical pupil filter, an optical grating diffraction light splitting principle and a soft pinhole detection method, and then difference calculation is conducted, so that high-precision measuring of absolute position is achieved. The dioptrate focus shifting type confocal microscopic differential measuring method and device are good in stability, high in synchronicity and capable of achieving common light path and high integration level measuring and imaging.