Monocular underwater measurement of structured light by scanning with vibrating mirrors

As a kind of visual detection technology, 3D structured light measurement technology has the advantages of high accuracy, rapid measurement, and active control, which is widely used in the research work of underwater surveys. Since light is refracted as it propagates underwater, the information of the measured object cannot be obtained directly from the captured image, which affects measurement accuracy. Therefore, it is necessary to correct and compensate for the refraction. In this paper, the structure of the combination of linear structured light and optical oscillator is adopted. In order to verify the function and accuracy of the system, experiments were conducted on object measurement in the air and underwater, respectively. The measurement experiments were performed on standard workpieces in air and the measurement results were compared with the real sizes of the workpieces. The relative error of the measurement was within 2%, which verifies the correctness of the construction of the system model and the accuracy of the calibration results. The results of the underwater experiments can approximate the measurement accuracy in air, which proves the correctness of the underwater model construction and the method of optical surface refraction compensation.