低畸变宽工作距机器视觉镜头光学设计

Low distortion wide working distance machine vision optical lens design

  • 摘要: 机器视觉镜头参数要求有别于其他镜头,为了保证测量精度,要求镜头的光学畸变很小甚至接近零,有的工作场合还要求有很宽的工作距等。设计一种机器视觉镜头,使用8枚球面镜片,采用固定后组,移动前组的调焦结构,实现了在空间频率120 lp/mm处,工作距从无穷远到超近摄0.1 m时,镜头畸变小于0.1%,MTF全视场大于0.4的性能要求。光学系统后组使用了两枚镜片,与后组只有一枚镜片的架构不同,不仅提升了光学性能,还有利于系统的平衡及稳定。整个光学系统没有非球面,也没有高折射率或高阿贝数的特殊玻璃,均为常见的冕牌玻璃和火石玻璃,降低了镜头成本,镜片加工及组装公差范围内量产优良率达90%以上。该镜头光学系统可广泛应用于机器视觉尤其是智能机器视觉行业。

     

    Abstract: 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.

     

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