At 02:17 PM 9/7/2005 +0300, you wrote:


>Russell. I'm surrounded by physicists here. Bad luck. :)
>The time required by energy transfer in such a thin phosphor film is
>incomparable
>with the human eye accomodation (continuous perception of successive frames).
>So, maybe the problem should be somewere else.
>
>cheers,
>Vasile

If the LED is moving then it will illuminate different receptors, so
a response time in the 100's of microseconds will smear the image,
despite being faster than the flicker fusion rate of the human eye by
several orders of magnitude.

However, I have at least one data point that the optical turn-off
time is claimed to have a time constant of < 0.5usec (90% decay in 1usec),
which is sufficiently fast for many such purposes (I didn't see the exact
proposed configuration for this thread, so I'm going to hedge). Say 3,000
RPM and 1 ft ~=0.3m in diameter (~1m in circumference), we have 50m/sec
surface velocity. The LED would move 0.05mm in 1usec, but 10mm in 200usec.

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist