Research on Calibration Methods for Photoelectric Deflectometer Based on Virtual Target

The photoelectric deflection meter is a non-contact instrument for detecting bridge deflection. To enable more flexible calibrate the photoelectric deflection meter, reduce the complexity of the calibration device, and improve the flexibility and accuracy of operation, a calibration method for photoelectric deflection meters based on a virtual target is studied. This method uses a light spot displayed on the screen as the target and calibrates the pixels of the display with a laser interferometer to ensure the traceability of the measurement results. The composition of the calibration device, the calibration method, and the principle are introduced, and static and dynamic calibration experiments are carried out on this basis. The experimental data show that for the static calibration experiment, at a working distance of 10 m, with a light spot step of about 5 mm and a maximum displacement of about 20 mm, the maximum indication error of the experimental results is −0.099 mm; at a working distance of 50 m, with a light spot step of about 25 mm and a maximum displacement of about 100 mm, the maximum indication error of the experimental results is −0.228 mm. For the dynamic calibration experiment, at a working distance of 10 m, with a maximum light spot displacement of about 10 mm, the maximum indication error is 0.05 mm; at a working distance of 50 m, with a maximum light spot displacement of about 50 mm, the maximum indication error is 0.315 mm. The experimental results show that using the display to generate a virtual target for calibration of the photoelectric deflection meter avoids the complexity of mechanical structures. Moreover, the display does not need to be moved during the calibration process, thus avoiding errors introduced by minor deformations of the mechanical device during movement. This method has the advantages of high flexibility and low cost, and provides a new idea for the calibration of photoelectric deflection meters.