LINEAR ARRAY CCD!!!!!! "Charles R. Patton" wrote: > Thomas W Leiperwrote: > "You could put a cheap linear filament bulb (like fish tank bulbs) > inside a rotating can with a vertical slit (aligned with the bulb > filament). Put one photocell close to the can for a reference signal. As > the can rotates you get a timing pulse." > > My thoughts: > On the surplus market, in the motors section of the various catalogs > there are often motors with the multi-faceted mirror attached. These > units have come out of laser scanner units. If you wanted to try Tom's > method, I think it would be much simpler to start with one of these as > they're balanced, and have good optical first surface mirrors. > Personally I think it would be a difficult challenge to obtain > satisfactory results for the following reason. Start with a reasonable > rotation rate of 3600 rpm on the scanner motor. Assume that your > optical path length is 10 ft long and that your detectors are 0.1 inch > in dia. Your first number is the pulse width on the detector. 0.1 in / > {10 ft * 12 in/ft * 2 * pi * (3600rpm/60 sec/min)} = pulse width in > seconds = 2.210485320721E-6 Or about 2 us. You now need to resolve > this to parts in 2^16. It's not going to happen. The fastest optical > diodes available today are in the 10 GHz range which would only get you > to 2^7 and those diodes and circuitry are not cheap -- they are state of > the art. In fact, it would take a bit of doing to even see, much less > decimate, the 2 us pulse with standard silicon solar cells. Some > photo-diodes have responses beyond this region but you have left the > easy designs and are starting to step into interesting territory. > > Regards, > Charles R. Patton > __________________________________________________________ > > Public Seismic Network Mailing List (PSN-L) > > To leave this list email PSN-L-REQUEST@.............. with > the body of the message (first line only): unsubscribe > See http://www.seismicnet.com/maillist.html for more information. __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>