Optical metrology is a highly interdisciplinary technology, which integrates optics with mechanics, electronics, computer science, informatics, mathematics, and many other disciplines. Consequently, every innovation in another field of science has the potential to drive new developments in optical metrology. For example, the invention of the laser in the 1960s opened vast new possibilities for optical measuring. Sensor technology such as video cameras in the 1970s and charge-coupled-device sensors in the 1980s replaced observation by eye and made optical measurement data accessible to computers. Since optical technologies typically produce millions of data points simultaneously, computer power has always been a central issue, and each new generation of computer technology gives engineers the opportunity to use well-known principles in new and innovative applications. During the first decade of this century, new light-emitting diode and complementary metal-oxide semiconductor technologies will revolutionize optical metrology. On-chip preprocessing of photon information enables massive parallel processing of data and perfect adaptation of lighting situations to the sensitivity of the photo sensor. Field-programmable gate arrays allow direct, very fast, and parallel processing of these data without the use of a personal computer. The rapid development of optimized mathematical routines for data treatment is increasingly important because it opens new doors for optical measuring principles in modern applications.
The transportation industry has always been a driver of innovative measurement techniques. In fact, optical metrology has been an indispensable technique that enables the transportation industry to make products more innovative, enhance quality, reduce cost, and accelerate time to market. Precise measurements of behaviors for materials and structures with advanced optical technologies allow engineers to design new lightweight vehicles, introduce new materials, and validate complex computational models. Therefore, optical metrology has experienced a great escalation in research, development, and applications within the transportation industry.
Three special sections on optical metrology in the automotive and transportation industry were published in Optical Engineering in 1998, 2003, and 2007, respectively. These special sections served as a forum for exchanging ideas among researchers in the field at that time. We feel that it is time for some subjects to be updated. This fourth special section highlights some different optical measuring principles in new applications and configurations. The focus has been laid on full-field optical measuring techniques in the areas of nano/microdisplacement measurement on microelectromechanical systems and microdevices, shape and displacement measurement on discontinuous surfaces, vibration measurement under running conditions, dynamic strain measurements of rotating tires, etc. If the described principles and applications stimulate our ideas to improve development and production in the transportation industry, this special section will have reached its goal.
Finally, we would like to express our sincere gratitude to all the authors who shared their knowledge with us in this special section and all of the peer reviewers’ valuable comments and their efforts to ensure the high quality of the special section. We also would like to thank the Editor of Optical Engineering, Dr. Ron Driggers, the Managing Editor, Karolyn Labes, the Peer Review Coordinator, Karen Klokkevold, and the other SPIE editing staff for providing both the opportunity and the technical support for publishing this special section.
Lianxiang Yang received his PhD in mechanical engineering from the University of Kassel, Germany. He is a professor in the department of mechanical engineering at Oakland University, Michigan. Prior to joining Oakland University, he was an R&D scientist at JDS-Uniphase, Canada, from 2000 to 2001, a senior engineer at Dantec-Ettemeyer AG, Germany, from 1998 to 2000, a research and senior research fellow at the University of Kassel, Germany, from 1991 to 1998, and a lecturer and associate professor at Hefei University of Technology, China, from 1986 to 1991. Professor Yang has multidisciplinary research experiences including optical metrology, experimental strain/stress analysis, nondestructive testing, and 3-D computer vision. He is a fellow of SPIE and the Chair of the Material Modeling and Testing committee of SAE International. He is also a Changjiang Scholar of Hefei University of Technology, China.
Andreas Ettemeyer studied mechanical engineering at the Technical Universities of Munich and Aachen, Germany. He graduated with a Dr-Ing degree in holographic interferometry at the University of Stuttgart. After two years as technical manager of a company for holographic measuring instruments, he started his own company in 1989 for development of laser speckle interferometry systems. With his company, he participated in several European research projects focused on the development of innovative 3-D measurement techniques. In 2005 he accepted a job as professor of mechanics at Munich University of Applied Science. In 2007 he moved to Switzerland and was appointed professor for technical optics and head of the Competence Center of Optics at Interstate University for Applied Sciences of Technology Buchs NTB.