Re Flying Spot Scanner for Roll Reader (960219)
By Robbie Rhodes
Wayne Stahnke recommends using parts from a point-of-sale barcode scanning machine, such as you see at almost every supermarket in the world nowadays! The light source is a HeNe (helium-neon) laser, which produces visible red light. The output power is 50 milliwatts maximum, as decreed by the US government. The exit pupil size is about 3 mm; the beam can be focused to about 0.1 mm diameter. The big barcode scanner also contains a nice multi- faceted rotating scanning mirror, and many nice optical parts for the photo detector.
This method is much simpler to build than the 2-axis galvanometer scanner, since the paper transport already provides the scan motion along the orthogonal axis.
A laser diode light source is probably inferior to the HeNe laser for this application. If the laser diode were better, it would replace the laser at the supermarket, but it hasn't!
-- Robbie Rhodes |
(Message sent Fri 23 Feb 1996, 06:47:47 GMT, from time zone GMT.) |
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