The lighting system in the machine vision system is an extremely important part. How to choose the light source scheme, its quality directly affects the subsequent image processing. Appropriate lighting is the key to the success of machine vision applications. Through appropriate light source lighting design, the target information and background information in the image can be optimally separated, which can greatly reduce the difficulty of image processing algorithm segmentation and recognition, and improve the positioning and positioning of the system. The measurement accuracy improves the reliability and comprehensive performance of the system. Conversely, if the light source is not properly designed for industrial smart cameras, it will result in half the effort in the design of image processing algorithms and the design of imaging systems. Therefore, the success or failure of the design of the light source and optical system is the primary factor that determines the success or failure of the system.

The following five aspects need to be considered when choosing lighting:

Is the surface smooth or rugged?

Is the surface dull or shiny?

Is the object curved or flat?

What is the color of the barcode or mark?

Is it to detect moving objects or stationary objects?

Machine vision LED light sources can generally be divided into the following categories according to their shapes:

1. Ring light source

The ring light source provides different illumination angles and different color combinations, which can better highlight the three-dimensional information of the object; high-density LED array, high brightness; multiple compact designs, save installation space; solve the problem of diagonally illuminating shadows; optional diffuser guide Light, the light spreads evenly. Application areas: PCB substrate inspection, IC component inspection, microscope lighting, liquid crystal calibration, plastic container inspection, integrated circuit printing inspection

2. Backlight

The high-density LED array surface provides high-intensity backlighting, which can highlight the contour characteristics of the object, and is especially suitable as a microscope stage. Red and white dual-purpose backlight, red and blue multi-purpose backlight, can be deployed in different colors to meet the multi-color requirements of different tested objects. Application fields: measurement of mechanical parts size, appearance detection of electronic components, IC, film stain detection, transparent object scratch detection, etc.

3. Bar light source

The bar-shaped light source is the preferred light source for the object to be measured with a larger square structure; the colors can be matched and combined freely according to requirements; the irradiation angle and installation can be adjusted at will. Application areas: metal surface inspection, image scanning, surface crack inspection, LCD panel inspection, etc.

4. Coaxial light source

The coaxial light source can eliminate the shadow caused by the uneven surface of the object, thereby reducing interference; some adopt the design of a beam splitter to reduce light loss, improve imaging clarity, and illuminate the surface of the object evenly. Application field: The series of light sources are most suitable for the surface scratch detection of metal, glass, film, wafer, etc., the damage detection of chips and silicon wafers, Mark point positioning, and packaging barcode recognition.

5. AOI dedicated light source

Three-color light illumination at different angles can illuminate and highlight the three-dimensional information of the solder; additional diffuser plate light guides to reduce reflection; different angle combinations; application areas: used for circuit board solder inspection.

6. Sphere integral light source

The hemispherical inner wall with integral effect uniformly reflects the light emitted from the bottom 360 degrees, so that the illuminance of the entire image is very uniform. Application field: It is suitable for the detection of curved surfaces, uneven surfaces, curved surfaces, or the surface detection of objects with strong reflections on metal and glass surfaces.

7. Linear light source

Ultra-high brightness, adopts cylindrical lens to focus light, which is suitable for various continuous inspection occasions of assembly line. Application areas: dedicated for array camera lighting, dedicated for AOI.

8. Point light source

High-power LED, small size, high luminous intensity; alternative to optical fiber halogen lamp, especially suitable as coaxial light source of lens; high-efficiency heat dissipation device, greatly improving the service life of the light source. Application field: suitable for telecentric lens, used for chip inspection, Mark point positioning, chip and liquid crystal glass substrate correction.

9. Combined bar light source

The four sides are equipped with strip lights, and the lighting on each side is independently controllable; the required lighting angle can be adjusted according to the requirements of the tested object, and the applicability is wide. Application cases: CB substrate inspection, IC component inspection, solder inspection, Mark point positioning, microscope lighting, packaging barcode lighting, spherical object lighting, etc.

10. Counterpoint light source

Fast alignment speed; large field of view; high precision; small size, easy to detect and integrate; high brightness, optional auxiliary ring light source. Application field: VA series light source is a dedicated light source for automatic circuit board printing machine alignment.