Large part metrology challenges and lessons learned

One of the most challenging applications of optical metrology methods is the measurement of large parts. These are parts that may be several meters in size such as used in large machinery or structures such as vehicles but still require a reliable measurement to achieve optimal performance and operational characteristics. A typical resolution in such applications may only be to tenths of a millimeter, but the relation ship of one point to another need to be known over many meters to this same resolution. Factors such as changes in the environment, warpage of the part and even drift in any holding fixtures can all complicate obtaining a reliable measurement of a large part. This paper will explore both the methods and the challenges typical in such application with example of potential means to mitigate these challenges.