The invention relates to multifocal holographic differential
confocal super-large curvature
radius measuring method and device, belonging to the technical field of optical precision measurement. The method comprises the following steps of: firstly, calibrating the long-focus value of a multifocal holographic lens by utilizing a differential
confocal system so as to reduce the
system error of measurement; realizing non-
contact high-precision positioning at the cat
eye position and the cofocal position of a measured piece by utilizing a differential
confocal fixed-focus principle; and subsequently, realizing the high-precision measurement of a super-large curvature
radius by utilizing a
geometrical optics principle. The device comprises a
point light source, a first spectroscope, a
collimator objective, the multifocal holographic lens, the differential confocal
system, an adjusting frame, a length measuring system and a moving track. The invention integrates the differential confocal high-precision fixed-focus principle and a multifocal holographic lens compression
optical path principle for the first time, has the advantages of small displacement distance of the measured piece, high
measurement precision, high measurement speed, strong ambient
interference resistance, no damage to the measured surface and the like and can be used for the high-precision non-contact measurement of the super-large curvature
radius.