What are the main techniques used in industrial lenses?Apexeloptic
Many people may not be able to tell the difference, so you have to understand the industrial lens first. The main function of the lens is to image the target on the sensitive surface of the image sensor. The quality of the lens directly affects the overall performance of the machine vision system. Reasonable selection and installation of lenses are an important part of machine vision system design. So optical lens manufacturers in the industrial lens mainly use what technology? Let’s take a look.
1. Focusing on technology
For the lens, the image distance of the object at different object distances is different. For the object to be observed, its imaging surface does not necessarily coincide with the photographic surface of the camera. To get a clear image, it is necessary to adjust the position of the imaging surface to coincide with the photographic surface, which is the process of focusing.
2. Zoom technology
Zoom means that the lens itself can be adjusted to have a wide range of focal length changes (usually measured as a multiple of the change in focal length, e.g. 4x zoom means that a large focal length is 4 times that of a small one). In the use of this lens, the zoom can be used to change the imaging magnification (between “large scene” and “local close-up” at will), which is highly adaptable and widely used.
Zoom realization: zoom process, through the optical system of two groups (or more) lens relative movement, change the whole system (lens) combination of focal length, and at the same time ensures that the position of the image plane does not move, so that the image magnification change and imaging are always clear.
It is different from single-group moving focusing, which is intended to change the position of the image surface (although it also causes minor changes in the focal length of the lens); Zoom, on the other hand, is intended to change the focal length of the lens (usually by a factor of several), and it requires that the image plane remain stationary.
3. Automatic aperture
Adjusting the aperture of the lens is essentially changing the aperture size of the aperture stop, to change the amount of light on the image surface to adjust the brightness. This process can be done manually or by motor drive, the latter way is automatic aperture adjustment.
4. Telecentric (focal stop) lens
Generally speaking, a telecentric optical path can be divided into object side telecentric optical path and image side telecentric optical path. The aperture is located in the focal plane on the image side of the lens (hence the name “telecentric”), and the entry pupil is located at infinity on the object side. Such an optical path is called the object side telecentric optical path. The characteristic of this optical path is that the incident main ray at the side of the object (shown in red) is parallel to the optical axis.
The aperture is located in the object side focal plane, and the exit pupil is located at infinity on the image side. Such an optical path is called the image side telecentric optical path. The characteristic of this optical path is that the main light emitted from the image side (shown in red) is parallel to the optical axis.
The two optical paths are essentially the same, being forward and reverse applications of the same optical path (telecentric). They often appear in measuring instruments, combined with practical application, which will show the characteristics of lattice, which needs to be paid attention to. The imaging characteristics of object side telecentric optical path are as follows: the size of the image is not sensitive to object distance, but it is sensitive to image distance; The imaging characteristic of image side telecentric optical path is that image size is very sensitive to object distance, but not to image distance.