The trend with Rb clocks is to try and make then smaller and cheaper. If all you need to do is detect the amount of light a one-pixel sensor is enough. If you divide the sensor into multiple pixels you just get more noise because fewer photons fall on each pixel. So a photo-transisor is ideal as a detector. Also another big problem with CCDs is that you have to shift the charged pixels out to an amplifier one pixel at a time so there is a small delay, the photo-transistor outputs the light level without delay and the associated shifter complexity. And in the end what do you do with all the pixels other then take an average?
I think the next generation of Rb physics packages will use a laser as the light source and have the laser, Rb cell and detector all in one glass envelope. I've seen one like this that is just tiny. But as I recall there was a problem using a laser, something about noise -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
