Abstract: Measuring instrument for blind hole of inside surface of thin cylinder is mainly used to measure the position,dimension and form of the blind hole and at the same time to measure the machining and foundry quality by image for inner surface of cylinder.It adopts the CCD image acquisition and image processing technology,precision machinery technology,computer real-time control technology to finish the measurement.The measuring principle and method,the function and advantage,the overall structure of the instrument are described.The design of the optical imaging system,the design of the mechanical system,the image processing procedure has been introduced in detail.The experiment results indicates the measuring instrument has met the measuring function and accuracy demands of the compensated hole.

Key words: form and position measurement, image processing, photoelectric detection, endoscope