3D Data Collection System Based On Laser Scanning

Laser scanning ranging technology is one of the most important technique of the three-dimensional data collection. It uses active measurement in non-contact mode, gets highly accurate three-dimensional data directly. It is able to scan for any object without cooperation. It has a series of unique advantages:high speed and precision of measurement, far range, perfect anti-jamming capability and unlimited applicability, etc. Currently, Laser scanning systems have large volume, high-power, slow scan rates and other issues. MEMS scanning mirror technology promote it to miniaturization, low power consumption, low cost and portable application, has an important research significance.The main innovation of this paper is the use of electrostatic MEMS scanning mirror in three-dimensional scanning ranging system, electrostatic mirror has a simple structure and high scanning frequency, low power consumption, small size and other characteristics. This paper designed a high-speed laser scanning ranging system, using electrostatic MEMS mirror as the scanning device, and took the actual measurement and data analysis. The main work of this paper include the following aspects:Firstly, this paper analysis and compare current mainstream method of laser ranging method, laser ranging detection methods, laser scanning method and the time identification method. According to the characteristics of miniaturization and high scan rate, paper designed a high-speed laser scanning ranging system. It uses MEMS scanning mirror as the scanning device. The distance information is obtained by the pulse time-of-flight ranging method, two-dimensional coordinate information is calculated based on frequency of MEMS scanning mirror.Secondly, this paper analyzes the principle and the scanning trajectory of MEMS scanning mirror. Electrostatic MEMS scanning mirror OP-6111 from Taiwan’s OPUS is chosen, the circuit is developed to drive scanning mirror and calculate coordinate. We developed a laser projection system and achieve the projection display of "SEU".Thirdly, the laser ranging system is designed based on Time-to-Digital-Converter chip TDC-GP21 by German ACAM and FPGA. It uses single detector to receive the echo signal. Time identification method is threshold method. Its time accuracy can achieve 91.5ps. In the actual ranging experiment, we use solid-state lasers to generate a 35ns pulse laser, use a PIN detector and an APD detector to provide start and stop signals for the TDC-GP21 chip. The error is less than 0.23m for close range.Finally, this paper designed the laser scanning ranging system based on MEMS scanning mirror and laser ranging technology. RS232 serial port is used for real-time communication between PC and ranging system. Measurement rate is up to 2333Hz. In this paper, we carried out a detailed analysis and the improved method to the measurement speed and the blind spot problem, we use the system scan a simple objects and restore the 3D figure.