Photonics Spectra Article - Multispectral Imaging Extends Vision Technology Capability
February 2015
Multispectral imaging takes the detection capability of machine vision beyond just color inspection. With wafer-level coating of multispectral filters, advanced multispectral cameras now can be designed in a compact form factor. The result: many new opportunities in high-speed line-scan imaging.
In color imaging, objects that are indistinguishable in monochrome images are discriminated by color.1 Color itself is a useful characteristic, of course, but what if you could look beyond just color to see what is invisible to the naked eye – including security inks printed on currency and copper circuits buried within electronic circuit boards?
It’s already possible, and here’s how it works. In a silicon sensor, either CCD or complementary metal oxide semiconductor (CMOS) color filters generally are coated at the wafer level to select different wavelengths – i.e., red, green and blue (RGB). Optical images captured line by line at these wavelengths are then used to identify specific objects of interest. Spatial correction allows the camera to align all color channels at the same object point with subpixel accuracy.1 The advantage of line scanning over area scanning for color imaging is that it provides three native RGB colors without Bayer decoding, which gives the best color image quality.
Click here to read the full Photonics Spectra article by Teledyne DALSA's Xing-Fei He.
