Project:Spacensus: Difference between revisions

Project:Spacensus (view source)

184 bytes added , 31 March 2011

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 ==How it works==
 ====Sensors====
-These sensors appear to be in working order. They'd should be safe to use below child-head height. They were manufactured in 1996 and use a [http://en.wikipedia.org/wiki/Laser_safety#Class_II Class II] laser rated at 3mW (peak), 2kHz 2% duty cycle, with a wavelength of 655-670nm ([[Media:Banner-q45bb6ll.pdf|datasheet]]). The model number is: Q45BB6LL
+These sensors emit a low power visible laser. They detect the beam reflection - if the reflection is obscured then we can surmise that a person is in the way.  The sensors were manufactured in 1996 and use a [http://en.wikipedia.org/wiki/Laser_safety#Class_II Class II] laser rated at 3mW (peak), 2kHz 2% duty cycle, with a wavelength of 655-670nm ([[Media:Banner-q45bb6ll.pdf|datasheet]]). The model number is: Q45BB6LL
-A good signal can be obtained at 1.5m by using a reflector made of aluminium tape.
+A good signal can be obtained at 1.5m by using a reflector made of aluminium tape but alignment is critical. [http://en.wikipedia.org/wiki/Bicycle_reflector Prism reflectors] are far more forgiving.
 ====State machine====