Commonly used lighting technologies in the machine vision industry

     LED machine vision light source is an important factor affecting the input of the machine vision system, which directly affects the quality of the input data and at least 30% of the application effect. Since there is no universal machine vision lighting equipment, the corresponding lighting device must be selected for each specific application instance to achieve the best results. Below, Xinxiwang introduces several common lighting methods.

1. Direct lighting:

The light is directed towards the object, resulting in a clear image. This type of light is effective when high contrast images of objects are required. But when it is shined on bright or reflective materials, it will cause mirror-like reflections. General lighting generally uses ring or spot lighting. Ring lights are a common form of general lighting that are easily mounted on lenses to provide adequate illumination of diffuse surfaces.

2. Coaxial lighting:

The formation of coaxial light is the changing divergence of light coming out of a vertical wall and hitting a beam splitter that directs the light downward. The camera looks at the object through the beam splitter from above. This type of light source is particularly helpful for detecting highly reflective objects. It is also suitable for detecting objects with inconspicuous areas affected by shadows produced by the surrounding environment.

3. Darkfield lighting:

Darkfield illumination provides low-angle illumination relative to the surface of an object. Use a camera to photograph the mirror so that it is within its field of view. If the light source can be seen in the field of view, it is considered to be bright field illumination. On the contrary, if the light source is not visible in the field of view, it is considered to be dark field illumination. Therefore, whether the light source is bright field illumination or dark field illumination is related to the position of the light source. Typically, darkfield illumination is used to illuminate parts of a surface that have protrusions or to illuminate changes in surface texture.

4. Diffuse lighting:

Continuous diffuse lighting is used when surfaces are reflective or surfaces have complex angles. Continuous diffuse lighting applies hemispherical uniform lighting to reduce shadows and specular reflections. This type of lighting is very useful for lighting fully assembled circuit boards. This light source can achieve uniform illumination within a solid angle range of 170 degrees.

5. Backlight:

A uniform field of light that shines from the back of an object. The side profile of the object surface can be seen through the camera. Backlighting is often used to measure the size of objects and determine their orientation. Backlighting creates great contrast. When applying backlight technology, surface features of objects may be lost. For example, backlight technology can be used to measure the diameter of a coin, but it cannot determine whether the coin is front or back.

In addition to the common lighting technologies introduced above, there are also some lighting technologies used in special occasions, such as strip light illumination that requires concentrated brightness in line array cameras; such as parallel light illumination used in conjunction with telecentric lenses in precision dimensional measurement. Technology; such as stroboscopic lighting technology that reduces the blur of the measured object in high-speed online measurement; structured light lighting technology that can actively measure the distance from the camera to the light source and polarized lighting technology that reduces stray light interference, etc.