When measuring the thickness of the coating layer of long solid rocket engine

the deflection of the cantilever beam will increase

which results in measurement precision of the thickness can not reach requirement of0.05 mm.In order to correct the deflection of the cantilever beam

a method for detecting the deflection of cantilever beam based on machine vision is proposed.A point laser is installed on the cantilever beam support

a reflector is installed on the other end. The charge coupled device（CCD） camera is used to collect the laser points on the reflector.The photoelectric image is processed and the center coordinates of the light point are calculated. The deflection errors of the two measurements are corrected according to the coordinates of the light points in different positions.The method is verified by experiments.The maximum error is not more than 0.03 mm

and the precision of thickness measurement meets the requirement of 0.05 mm.