Ring light section based image measurement system for deep holes with complicated inner surfaces

An image detection method based on the ring light section method was developed to measure deep holes with complex surfaces, especially rifled gun barrels. This method employs the ring light spot image formed by a ring laser projected onto the inner surface. The system identifies intensity extremes, corrects for centering errors, and uses parametric regression to measure the profile lines and their dimensional parameters on the inner surface. Multiple profile lines are used to reconstruct the entire inner surface of the deep hole in three dimensions. The technique has a precision of 0.1 mm with a 130-mm-diameter pipe, which satisfies the quality control requirements of artillery barrels.