Design of a double-telecentric optical system based on machine vision

With the development of industrial production, machine vision is playing a more and more important role in measurements and judgments. For the machine vision system, double-telecentric optical system can be used for visual inspection and measurement with good imaging effect and imaging accuracy. This paper mainly introduces a low telecentricity and low-distortion double-telecentric optical system. The designed system consists of only 5 lenses, which will reduce production costs. The object field of view is 50mm, the working wavelength is visible light, the total length of the system is 274mm, the working distance is 110mm, the maximum distortion is less than 0.025%, the object side telecentricity is better than 2.6×10^-6 milliradians, and the image side telecentricity is better than 7.6×10^-4 milliradians. The MTF is greater than 0.3 at the Nyquist frequency 91 lp/mm for the full field of view. The MTF curve of the optical system is close to the diffraction limit, which indicates the optical system has good imaging quality in space. The optimizing process and tolerance analysis of the optical system are showed in this paper. The results indicate that the double-telecentric optical system can be used in the production and inspection of parts in the industry.