Laser optical measurement systems and their application to the on-line error compensation of coordinate measuring machines

This dissertation presents the measurement principles, theoretical analysis and experimental results of a number of new laser optical measurement systems and the application of these systems to the on-line error compensation of coordinate measuring machines (CMMs). It can be divided into two parts comprising six papers.; The first part, including the first two papers (Chapters 2 and 3), investigates the feasibility of the concept of on-line error compensation of CMMs. A multi-degree-of-freedom measurement system (MDFM System) was developed based on the principles of laser alignment and autocollimation, which can simultaneously measure five error components of each axis of a CMM with an accuracy of better than 1 {dollar}mu{dollar}m for straightness measurement and better than 0.5 arcsec for pitch and yaw measurements. This system along with two other similar systems was then implemented on a horizontal-arm CMM for on-line error compensation. Two error synthesizing models, one for the conventional off-line error compensation system and the other for the on-line error compensation system, were developed to predict and correct the errors at the probe tip. Diagonal tests using an interferometer as the reference showed that the on-line system can further improve the accuracy of the CMM as compared to the off-line system.; The second part, including the remaining four papers (Chapters 4 {dollar}sim{dollar} 7), focuses on further improving the accuracy of the measurement systems which determines the performance of the on-line error compensation system. A new generic method of angle measurement was developed based on the internal-reflection effect (AMIRE) to improve the performance of the angle measurement system. With this new method, measurement sensitivity can be significantly increased by using a multiple-reflection scheme and nonlinearity error can be minimized by optimizing sensor parameters. Based on the principles of AMIRE and a single-mode fiber beam delivery system designed to improve the pointing stability of the reference beam, a new multi-degree-of-freedom geometric error measurement system (M-GEMS) was developed with a higher resolution (ten times better), more compact size, and a lower cost as compared to the MDFM System. Another study uses a pair of right-angle prisms as the reflection prisms in AMIRE, which resulted in a further simplified optics, reduced size and lowered cost.