Optical lenses are generally referred to as camera lenses or photographic lenses, referred to as lenses, and their function is low price YLF laser crystal. Optical lenses are important components in machine vision systems and play a key role in image quality. They affect several key metrics of imaging quality, including resolution, contrast, depth of field, and various aberrations. Not only are there a wide variety of lenses, but the quality difference is also very large, but the average user often pays insufficient attention to the selection of the lens when designing the system, resulting in failure to obtain an ideal image or even causing system development to fail. The purpose of this paper is to summarize the relationship between various factors by introducing the classification and main parameters of various common lenses, so that the reader can master the selection skills of lenses in industrial optical systems.
According to the size of the effective image field
Mount the photographic lens on the front end of a large retractable black box and install a large frosted glass at the back end of the black box. When the aperture of the multispectral/cleartran and standard CVD ZnS optics is turned to a large value and the infinity is adjusted, the images on the frosted glass are all located in a circular area, while the outside of the circle is dark and has no image. The circular area of the image is called the large image field of the lens. At the center of this large image range, there is an area that allows a scene from infinity to form a clear image. This area is called a clear image field. The target surface of a camera or camera is generally located within a clear image field. This limited range is called the effective image field. Since the target size of the camera used in the vision system has various models, it is important to note that when selecting the lens, the effective image field of the lens should be greater than or equal to the target size of the camera, otherwise the corners of the image will be blurred or even no image. .
Classification according to focal length
According to whether the focal length can be adjusted, it can be divided into two types: fixed focal length lens and zoom lens. According to the length of the focal length, the fixed focal length lens can be divided into four categories: fisheye lens, short-focus lens, standard lens and telephoto lens. It should be noted that the length of the focal length is not based on the *** value of the focal length, but the size of the image is the main basis, so when the size of the target is not equal, the focal length of the standard lens is also different. There is a zoom ring on the zoom lens. Adjusting the ring allows the focal length of the lens to be flexibly changed within a predetermined range. The ratio of the long focal length value to the short focal length value of the zoom lens is called the zoom magnification of the lens. The zoom lens can be divided into two categories: manual zoom and power zoom.
Since the zoom lens has the characteristics of continuously changing the focal length value, it is very convenient to use in the case where it is necessary to frequently change the photographic field of view, so it is widely used in the field of photography. However, due to the large number of lenses and complicated structure of the zoom lens, the large relative aperture cannot be made too large, resulting in low image brightness and poor image quality. At the same time, it is difficult to target various focal lengths and various adjustments in the design. The focal length is corrected for aberrations, so the image quality cannot be compared with the fixed-focus lens of the same grade.
According to the lens interface type
There are many different types of interfaces between the no doped YLF crystal and the camera. Industrial cameras commonly include C interface, CS interface, F interface, V interface, T2 interface, Leica interface, M42 interface, M50 interface, and the like. The difference between the interface types and the lens performance and quality is not directly related. It is only the interface mode is different, and generally can also find the transfer interface between various commonly used interfaces.