Posted March 6, 2019 at 4:17 am by by56014904

Selection of optical accessories in optical vision

Industrial cameras, image processing software and optical vision sources are important in optical vision systems, but procurement high efficiency thin-film multilayer optical filter are also an indispensable component of the system, directly affecting the quality of imaging, affecting the implementation and effectiveness of the algorithm. Therefore, its role is also indispensable. If the system wants to fully play its functions, the optical components must be able to meet the requirements.

Choosing the right optical accessory is an important step in reducing the cost of the optical vision system and improving system stability. When choosing a lens for a vision system, you should analyze the following factors to determine the appropriate lens for your specific application.
Distance constraint

The space required for automated purchase high purity optical grade sapphire optics systems and assembly lines varies widely, and different system applications require different installation spaces. The so-called working distance refers to the distance between the object and the front end of the industrial camera lens when the image is in the focal length range. It limits the space required for the vision system and the devices that work with the vision system.

There are some applications where the working distance is very flexible, and both near-focus lenses and long working distance video microscope heads can be used. For other applications, the working distance may be only a few centimeters or even a few millimeters. Therefore, in the limit range, it is necessary to refocus through the lens to change the working distance.
When the product area of ​​interest and the product line may change during the inspection process, this requires that the vision system and visual components must be flexible enough to be adjusted according to the working distance. When selecting a lens, consider changing the working distance when the object space (the distance between the object and the lens) is limited and the image space (the distance between the lens and the image) is changed.

The performance of an optical system depends on the degree of image blur allowed, which may result from the positional drift of the object plane or image plane. Depth of field is the acceptable blurring range caused by the movement of the detector. It depends on the F-number of the work and can be used to measure the concentrating power of the lens.
The F number increases as the lens aperture decreases. Reducing the lens aperture means increasing the F-number, which increases the depth of field of the system, but it reduces the amount of light entering the sensor, so it is necessary to increase the level of illumination to compensate.

It is important to note that you should not confuse telecentric lenses with large depth of field lenses. The telecentric lens allows the optical vision system to control the magnification and eliminate potential errors, so objects of the same size are consistent in height on the photo. Usually telecentric lenses have a working range that creates a limited depth of field at each working distance.
Object characteristics

Before selecting an optical accessory for an procurement optical lens manufacturer/supplier system, the object characteristics and analysis environment must be determined. This viewable area is called the unobstructed field of view (FOV) and the camera chip size is very important to determine the optical magnification required for the FOV.
Optical magnification is quite important for camera-matched lenses of different size chips, however, lens magnification and microscope magnification are different. The latter is determined by the length of the light pipe and the actual focal length of the objective lens, while the optical component magnification is mainly considered to be the size of the camera chip.
Therefore, the characteristics of the object are also important. The ability of the lens to recognize a line or a point of a specific width under specified lighting conditions determines its resolution. The resolution determines the sharpness of the image.

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