请帮我润色下面这段英文As a non-contact optical nondestructive testing technology structured light 3D measurement has the advantages of high accuracy fast speed and good robustness and is widely used in industria

Structured light 3D measurement is a non-contact optical nondestructive testing technology that offers high accuracy, fast speed, and good robustness, making it widely used in various industries, such as industrial defect detection, face recognition, and reverse engineering. With the increasing demand for high precision 3D reconstruction in industrial manufacturing, this Thesis delves into the technical principle of structured light 3D imaging, including package phase calculation, absolute phase unwrapping, system calibration, and 3D reconstruction.

The Thesis covers the following main contents:

1. The design of a structured light three-dimensional measurement system that adopts a side multichannel projection lighting scheme to effectively address the measurement blind area shielded by components. The system also utilizes a double telecentric lens to reduce distortion, increase depth of field, and improve measurement accuracy.

2. A method of telecentric lens calibration that combines Zhang Zhengyou calibration method and Tsai two-step method was proposed. The exocentric model was used to solve the exocentric parameters, and further used to calibrate the other internal parameters. The inverse camera method combined with phase information was used to calibrate the projector, and then the joint calibration of the system was completed. The proposed method has lower reprojection error and higher calibration accuracy compared to traditional methods.

3. An improved multi-frequency heterodyne method was proposed to solve the absolute phase using the four-step phase shift method to solve the enveloping phase of the object and the multi-frequency heterodyne time-domain phase expansion method to solve the absolute phase. This method reduces the expansion error rate by 75%, effectively suppresses phase unfolding errors, and improves robustness.

4. The proposed three-frequency and four-step phase shift coding scheme was compared with the traditional multi-frequency heterodyne method, and the results show that the proposed method can effectively suppress phase error and improve 3D topography measurement accuracy.

Overall, this Thesis contributes to the development of structured light 3D measurement technology, particularly in system design, calibration, and phase unwrapping, offering more accurate and robust 3D reconstruction for industrial applications