Chromatic confocal displacement measurement using a double-sided phase diffractive lens

A chromatic confocal displacement measurement (CCDM) system using a double-sided phase diffractive lens (DPDL) is demonstrated. The DPDL is designed to produce a strong dispersion, minimize the optical structure and reduce the difficulty of fabrication and assembly, in addition to reducing the weight and size of the probe of the CCDM. A CCDM experimental system was set up based on the DPDL, and the results of the measurement experiments show that the axial measurement range of the CCDM system reaches 9.463 mm in the working wavelength range (500-700 nm), the relative error is less than 0.022% and the axial resolution near the designed focal length is better than 0.5 µm.