Measurement accuracy analysis and error correction of CCD light-projection diameter measurement system

摘要

The error source of the external diameter measurement system based on the double optical path parallel light projection method are the non-parallelism of the double optical path, aberration distortion of the projection lens, the edge of the projection profile of the cylinder which is affected by aperture size of the illuminating beam, light intensity variation and the counting error in the circuit. The screw pair drive is applied to achieve the up-and-down movement in the system. The precision of up-and-down movement mainly lies on the Abbe Error which is caused by the offset between the centerline and the mobile line of the capacitive-gate ruler, the heeling error of the guide mechanism, and the error which is caused by the dilatometric change of parts resulted from the temperature change. Rotary mechanism is achieved by stepper motor and gear drive. The precision of the rotary mechanism is determined by the stepping angle error of the stepper motor, the gear transmission error, and the heeling error of the piston relative to the rotation axis. The method of error modification is putting a component in the optical path to get the error curve, which is then used in the point-by-point modification by software compensation.