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Written by: Danielle Burke on May 25th, 2017
This post looks at machine vision strobe lighting, the reason why you would use strobe lighting in machine vision applications and multi-wavelength strobe applications.
Fast moving production lines where articles need to be inspected while in motion can be particularly challenging for machine vision systems. Due to the speed of the line, the camera may produce blurred images or an incorrect inspection reading. One solution to ensure accurate inspection is to use a strobe light.
In machine vision, illumination can be set up using one of two options, either strobe or continuous light sources. A strobe light can produce increased intensity to enable better image capture from the machine vision camera and can enable the light to last longer, as a result of it being powered only when required. Control of the strobe needs to be very precise. The timing must be accurately coordinated with the image acquisition; otherwise the images may show up unclear.
To ensure the strobe light enables accurate image capture it must be set at appropriate pulse duration. The duration of the strobe pulse can vary greatly depending on the duration of the time it takes the camera to capture the image of the item under inspection. This image capture is usually in the order of microseconds.
There are two commonly used strobe models in machine vision lighting: simple low current and high energy over-current drive. In both cases the flash is coordinated with the camera exposure to ensure the optimum image acquisition. The main differences between the strobe models used are the variation in the light pulse duration in comparison to exposure time, the current levels used to power the pulse and the available illumination intensity. The simple low current model is well suited for use under relatively low speed strobing applications illuminated by high brightness LED lights. The high energy over-current drive model is suited for use in high speed applications.
To enable rapid data acquisition and analysis, multispectral strobe patterns with up to four optically independent strobe lines are possible. For example, a ProPhotonix COBRA MultiSpec configured with twelve wavelengths may be programmed to emit three wavelengths per strobe line. With this set up, the system would capture data on all twelve wavelengths in one strobe cycle with a total delay and response time profile of less than one microsecond.
ProPhotonix offers a range of products which can be used for strobing in machine vision lighting. ProPhotonix offers a range of LED ring, spot, area and LED line lights. ProPhotonix also offers custom solutions where we can adapt many of our existing systems including strobe options to meet your specific requirements. Contact us at email@example.com for more information.