Three-dimensional morphology measurement of underwater objects based on the photoacoustic effect

Complexities of the underwater environment can seriously affect many underwater detection means, especially the influence of light scattering by water. To solve this problem, a three-dimensional (3D) morphology measurement method is proposed based on the photoacoustic effect. In this method, a measurement object is irradiated with pulsed laser light to produce ultrasonic waves via the photoacoustic effect. A probe collects the ultrasonic signal and subsequent data processing can yield complete object detection. This approach can make full use of the advantages of high precision and good directivity of laser ranging and completely avoid the influence on the laser of backscattering from water. The results yield a displacement measurement accuracy of less than 0.5 mm and an average error of 3D reconstruction of 0.21 mm, demonstrating great application potential.