Time-of-Flight Techniques

Abstract

Three-dimensional (3D) shape measuring techniques, using a combination of grating projection and a most frequently used mathematical toolFourier fringe analysis-have been deeply researched and are increasing in number. These kinds of techniques are based on the idea of projecting and superposing a carrier fringe pattern onto the surface of the tested object and then reconstructing its corresponding 3D shape from the deformed fringe pattern modulated by the height of the tested object and captured by a camera from another view direction. In this chapter, theCONTENTS7.1 Introduction ................................................................................................ 196 7.2 Basic Principles of 3D Dynamic Shape Measurement Based on FTP .... 1987.2.1 Measuring System Based on Grating Projection ....................... 198 7.2.2 3D Phase Calculation and Unwrapping ..................................... 201 7.2.3 System Calibration ......................................................................... 203 7.2.4 Measuring Accuracy and Measurable Range ............................ 2037.3 Some Applications of 3D Dynamic Shape Measurement .................... 204 7.3.1 3D Dynamic Shape Measurement for Slow-MovementProcesses ......................................................................................... 204 7.3.2 3D Dynamic Shape Measurement for High-MovementProcesses ......................................................................................... 205 7.3.3 3D Dynamic Shape Measurement for Rapid Rotation andInstantaneous Process ................................................................... 206 7.3.4 3D Dynamic Shape Measurement for Breaking Objects.......... 2087.4 Time-Average Fringe Method for Vibration Mode Analysis ............... 209 7.4.1 Fundamental Concept ................................................................... 210 7.4.2 Experimental Results .................................................................... 2127.5 Advantages and Challenges ..................................................................... 214 Acknowledgments .............................................................................................. 215 References ............................................................................................................. 215basic principles and some proof-of-principle applications of 3D dynamic shape measurement using grating projection and Fourier fringe analysis will be demonstrated to review our research results of this combined approach. This chapter mainly focuses on this technology and its applications that we have developed over the past 10 years. Section 7.1 gives a brief introduction of 3D shape measurement using grating projection. Section 7.2 describes the basic principles of 3D dynamic shape measurement using grating projection and Fourier fringe analysis. Section 7.3 demonstrates some typical applications that we achieved. Section 7.4 expresses the fundamental concept of the time-average fringe method for vibration mode analysis and its experimental results. In the last section, we discuss the advantages and challenges of this technique and the current development of real-time measurement in this research field.