Design Of Low-Light-Level Imaging Device

Photographic film is one of the common photosensitive matierals and information carriers. During the process of manufacture, various defects may appear on the film under the influence of production facilities, processing techniques and manual operation. The main source of defects is the coating process, which is one of the four main film-manufacturing process. We have designed and developed a low-light-level imaging device, which can realize the observation of film on the coating line to help workers discover impurities on the film, and then clear them away manualy.By applying the principle of night vision technology and optical imaging technology, choosing and matching the low-light-level image intesifier and lens, designing and making the mechanical shell and fixing settings of imaging system, assembling and adjusting the device on-line, we developed the low-light-level imaging device. The device has high observing resolution, long operating distance and large field of view. Its observing resolution can reach 12.5lp/mm, the clear imaging range in object space is between 200mm to 300mm, and field number is greater thanφ50mm. Experiment and test on-line at the coating workshop in the second film factory of Lucky Group proves that the device satisifies all the requirements.As the object lens used in this device is not special for the imaging system, and its transmission ratio of the infrared light source (λ=940nm) is not high. We have designed a low-light-level infrared objective with the application background of the project using CODE V , an optical design software. The objective has high infrared transmission, large relative aperture and high resolution. Its optical parameters: effective focal length f=26mm, F number F/# =2.5, half field of view in object space HFOV=18.5°. The MTF is above 0.2 at 63lp/mm, and above 0.3 at 45lp/mm which is the representative resolution of the image intensifier.The main innovations achieved in this dissertation are as follows:⑴Have applied both night vision technology and optical imaging technology to the observation of film successfully, and have got good result;⑵The low-light-level imaging system designed has achieved high resolution observation of tiny impurities with long operating distance and in large field of view.⑶We designed the low-light-level infrared objective using common optical...