Manufacturing process of machine vision lens

In machine vision, the lens is an important part of acquiring images, but it is often regarded as an inconspicuous accessory. Some people think that a lens is just a combination of several lenses and metal parts, and it is not worth investing too much budget and consideration. In today's article, we will start from the optical design stage and discuss with you the birth process of a lens. I believe that after reading it, everyone will understand that the lens accessory is not as simple as imagined. 1. Optical design stage At this stage, according to the customer's needs, calculate what shape of lens (curvature, thickness, material, etc.) and the distance between each lens are needed, and shape the structure of the lens. This stage involves a lot of calculations to continuously and repeatedly optimize, so that the imaging of the optical system is continuously improved (optical performance such as MTF, distortion, etc.). In addition, lighting analysis related to stray light, ghosting, and hot spots will also be done at this stage. Usually use ray tracing software (ZEMAX, TracePro, etc.) to complete this stage. If the imaging quality is calculated under the conditions of the specified lighting and camera sensitivity, the imaging defects can be calculated before the trial. Second, the mechanical design stage On the basis of the previous stage, the structure of the lens was perfected and the final size of the lens was defined. Here also need to consider the difficulty of lens assembly, so as to lay the foundation for subsequent improvement in yield and saving assembly costs. Third, the lens production stage The production of optical lenses is a time-consuming and rigorous process. From the mixing and melting of glass materials, the cutting of blanks, to the rough grinding, fine grinding (to meet the requirements of thickness and curvature), polishing (to meet the requirements of aperture and irregular aperture) and core taking (to achieve eccentricity) , The height of the outer diameter and other requirements), and then to the final coating (to meet the requirements of transmittance and transmission wavelength), each step will determine the quality of the final imaging! Fourth, the lens assembly stage Once all the incoming materials are gathered, the production of the lens can proceed. Different types of lenses naturally differ greatly in the ease of assembly. When assembling high-resolution, large NA lenses, because the optical system is extremely sensitive to tolerances such as lens eccentricity, sometimes it is necessary to implement core alignment assembly technology, which greatly improves the MTF of an assembly. If assembling a zoom lens or an iris lens, the assembly process will be more cumbersome. At this time, complicated parts such as curved groove barrels, diaphragm blades and actuating rings will be involved, and the assembly time will naturally be longer. Five, lens inspection stage At this stage, all parameters required by customers: such as magnification, working distance, resolution, distortion, relative contrast, including appearance, environmental testing, etc., need to be tested to ensure the quality of shipments. The lens detection system can detect multiple parameters of the lens at the same time. The MTF (transfer function) tester guarantees the authenticity of the comparison with the design value to the greatest extent in the sample stage.