The invention discloses a bilateral misplaced differential
confocal ultra-large curvature
radius measurement method, belonging to the technical field of optical precision measurement. According to themethod, in a
confocal measurement
system, firstly, large and small virtual pinhole detection areas are set through
software on an
airy disk image detected at CCD and two
confocal characteristic curves detected by the CCD are sharpened through subtraction treatment, then, bilateral misplaced differential subtraction is executed for the sharpened confocal characteristic curve so as to obtain a high-sensitivity differential confocal characteristic curve; secondly, based on a
null point of the bilateral misplaced differential confocal characteristic curve and a focal point of the confocal measurement
system are accurately corresponding to the characteristics, high-precision focus-fixed locating is executed for each characteristic position point in ultra-large curvature
radius measurement, andconsequently, high-precision measurement of ultralong
focal length. Compared with the existing large curvature
radius measurement method, the method provided by the invention has the advantages, suchas high precision, high environment
interference resistance and simple structure, and has wide application foreground in the technical field of optical precision measurement.