Low distortion wide working distance machine vision optical lens design

The optical parameter requirements for machine vision lens are different from the other areas. In order to guarantee the measurement precision, the lens distortion is required to be small or even close to zero, and some workplaces also require a wide working distance, etc. This design was about a kind of optical lens based on machine vision cameras which used eight pieces of glass lenses. By fixing rear group and moving front group to realize the working distance from infinity to super close-up 0.1 m at the spatial frequency 120 lp/mm, the lens distortion was controlled within 0.1% and the MTF of full field of view was greater than 0.4. This optical system used two pieces of lens as its rear group, which was different from other structures with only one lens. It was not only good for improving optical performance, but also good for the balance and stability of the system. There was no aspherical lens or special glasses with high refractive index and high abbe number, it used common crown and flint glasses to reduce the lens cost, and the good rate of the mass production was more than 90% within the tolerance range of lens processing and assembly. This optical lens system can be widely used in machine vision especially in intelligent machine vision industry.