Scanner lasers and safety
In surplus catalogs I often see Lasers from scanners at stores
advertised. Always they have a warning about their power and dangers .
I would like to know how come there clerks and who use these scanners are not
in any danger? These things must have considerable more power than our
There are two parts to the answer.
First, the scanner beams are moving very fast. Even if you looked
directly into the scanner (Do not DO IT!) the exposure would last only
a very short time. As with the sun, some things are in the appropriate
brightness range that staring at them can do damage which a quick
glance would not cause.
Second, the lasers used are fairly low power, much less than a watt.
The problem is that the power is concentrated in a small beam which
can focus very tightly on the retina and cause damage even when a
lightbulb with comparable power output would barely be visible.
Remember, the retina is irreplacable. Always use appropriate eye
protection measures when working with lasers or other high power density
light sources. To find out the appropriate safety measures consult
with the manufacturer.
gregory r bradburn
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Update: June 2012