An on-line optical inspection and monitoring system is externally mounted to existing man way service access within the combustor housing. A replacement man way cover having an optical window is mounted to the combustor housing. One or more optical cameras are oriented so that the camera field of view (FOV) is directed through the man way cover optical window. The camera FOV is moved to plural positions within the combustion section, such as under control of an automated motion control system, and images are captured. Multiple images are combined to form a composite image, which may include an image of an entire transition within the combustion section. Visual images and/or infrared (IR) thermal images may be captured. Thermal image information is correlated with component temperature. Image information is utilized to determine vibration characteristics of the imaged components.