Barcodes. Why do barcodes have the thick and thin lines and numbers on them. Also, why are lasers used to scan them?
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The numbers are for humans, the bars are for the laser. The laser sweeps across the bars and a sensor looks for reflected laser light. The white reflects a lot and the black very little, and this “on” and “off” is converted into 1’s and 0’s. This makes a series of longer and shorter pulses, depending on the angle at which the laser sweeps across the bars. Good scanners sweep at many angles, hoping to get lucky. The relative length of the string of bits is used, more like Morse Code than traditional computer numbers, to detect the coded numbers.
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