The bright spot of the light source is usually the place where the beads of the light source shine directly. Even if the diffuser is added, it is similar, but the situation will be slightly reduced. And when many beads are arranged together, the center of the bead matrix (which we think is a matrix) is always brighter than around. Because there are more lights in the center.
When a lens is imaged, the center of the lens always collects more light than the surrounding area, so even if a large, uniform surface is imaged by the lens, the center is always brighter than the surrounding area.
Therefore, the actual image of the lens bright spot, the situation may be more complex. We need to look at the specific light source and the height and angle of the lens.
The spot of lens can directly determine the uniformity of field-of-view imaging. Therefore, the location and size of the spot of different light sources need specific experiments to know. As to whether the selected light source is suitable for the case, only the experiment is known. In practical application, although we think that the more uniform the field of view, the better, but many times it is difficult to achieve very uniform, so as to meet the needs of the project, even if there are some non-uniform, it can also solve the problem.
What is the uniformity of light sources?
Uniformity: In all machine vision applications, uniform illumination is required, because the illumination intensity of all light sources decreases with the increase of distance and the deviation of illumination angle, so when illuminating large areas of objects, there will be greater problems, sometimes only the central position of the field of view can be kept uniform.
What is the effect of uneven light source uniformity?
Non-uniform light can cause non-uniform reflection. There are three main influencing factors:
First, for the field of vision, the part of the camera field of vision should be uniform. Simply put, the dark area of the image is the lack of reflection, and the bright spot is that the reflection is too strong here.
Secondly, uneven light will cause more light in some areas of the field of vision than in other areas. This results in a non-uniform reflection on the surface of the object (assuming that the reflection of light on the surface of the object is the same).
Thirdly, the uniform light source compensates for the change of the angle of the object surface. Even if the geometric shape of the object surface is different, the reflection of the light source in each part is uniform.
POMEAS has a variety of machine vision light sources, please consult customer service intentionally!
You may also be interested in the following information