ROBERT DAVID TURNBULL. An Investigation of Structured Light Scanner Calibration Degradation (Under the direction of DR. ED MORSE)Structured light scanning is a measurement technique using two images taken at a well-known angle to each other. Using the angle, the distance between where the images were taken, and the principles of triangulation a 3-dimensional surface can be generated. The accuracy can be improved by using additional techniques to improve the measurement. One of the more common techniques seen on commercial structured light scanning systems is the use of fringe projection. One major inconvenience/workflow interruption with these types of systems is that they require frequent calibration, as the angles and distances described above may change over time. Traditional touch probe coordinate measuring machines in industry typically require calibration every 6 to 12 months. For maximum accuracy most structured light scanners are calibrated at least once a day or before each new measurement. While the calibration is rather quick and simple to perform it still can be an interruption to the workflow in an industrial environment. The goal of this project is to explore the underlying reasons why the calibration deteriorates so rapidly and develop recommendations for users to mitigate the consequences of this deterioration. The current hypothesis is that the main cause is related to either the environment or to a temporal factor of the system. If the temperature of the environment is a leading factor for the rapid deterioration it will be rather simple to test. This will be done by measuring a calibrated object over the course of a couple weeks while at the same time recording the temperature, pressure, and relative humidity of the environment. The data will then be analyzed to determine if there is any correlation between the environmental or temporal factors.It was found that there was no recognizable correlation to temporal factors. There were correlations to the environmental factors, the strongest being to relative humidity. It is likely the correlation to temperature would have been more noticeable if the temperature range for the environment had been larger, but the experiments were conducted in a lab that was temperature controlled within 2 degrees Celsius. It is recommended based on the results of this research, to calibrate the system every one to two days. If this is not possible then it would be recommended to track the environment the system is in and recalibrate when the environment changes significantly.