The main role of LED light sources in machine vision systems

 In machine vision systems , the role of light sources is mainly reflected in: 1. Highlighting measurement features and simplifying image processing algorithms; 2. Overcoming the interference of ambient light and improving image signal-to-noise ratio; 3. Improving the positioning, measurement, and identification accuracy of the visual system , and the running speed of the system; 4. Reduce the complexity of system design.

At present, machine vision LED light sources can usually be divided into the following categories according to their shapes:
1. Ring light source: Provides different illumination angles and different color combinations, which can better highlight the three-dimensional information of objects; high-density LED array, high brightness; various compact designs , saving installation space; solving the problem of diagonal shadows; an optional diffuser plate can be used to guide light and diffuse the light evenly. Application areas: PCB substrate inspection, IC component inspection, microscope lighting, liquid crystal correction, plastic container inspection, integrated circuit printing inspection.
2. Backlight: A high-density LED array surface is used to provide high-intensity backlight illumination, which can highlight the contour features of the object and is especially suitable as a microscope stage. Red and white dual-purpose backlights and red and blue multi-purpose backlights can be deployed in different colors to meet the multi-color requirements of different objects under test. Application areas: measurement of mechanical parts dimensions, appearance inspection of electronic components and ICs, film stain detection, scratch detection of transparent objects, etc.　
3. Bar light source: It is the first choice light source for larger square structures to be measured; colors can be matched and combined freely according to needs; illumination angle and installation can be adjusted at will. Application areas: metal surface inspection, image scanning, surface crack detection, LCD panel detection, etc.
4. Coaxial light source: It can eliminate shadows caused by uneven object surfaces, thereby reducing interference; some use a spectroscope design to reduce light loss, improve imaging clarity, and evenly illuminate the object surface. Application fields: The series of light sources are most suitable for scratch detection on surfaces with extremely high reflectivity, such as metal, glass, film, wafers, etc., damage detection of chips and silicon wafers, Mark point positioning, and packaging barcode recognition.
5. Linear light source: ultra-high brightness, using cylindrical lens to focus light, suitable for various assembly line continuous inspection occasions. Application fields: Special for array camera lighting, special for AOI.
6. Point light source: high-power LED, small size, high luminous intensity; a substitute for fiber optic halogen lamps, especially suitable as a coaxial light source for lenses, etc.; efficient heat dissipation device, greatly extending the service life of the light source. Application areas: Suitable for use with telecentric lenses, used for chip detection, Mark point positioning, chip and LCD glass substrate correction.