[Halld-pid-upgrade] LED lights and yellowing

[Shepherd, Matthew]

The discussion got cut short a little at the end of the meeting...

I thought that most yellowing of materials was due to UV emissions which are fairly strong in fluorescent lights.  I suspect the bar assembly lab at SLAC utilized typical fluorescent lights.  Did the have UV filters?  I believe LED lights produce much less UV than fluorescent tubes.

If this is still a concern, an option is to use a square pulse generator with a variable duty cycle, set to say 5% to power the LED strip.  Then, in software, it should be easy to cut out the camera frames that have the LED off.  I'm sure something like computing the total pixel intensity would be a fast discriminator.  If we're going to stitch frames together to make a time lapse movie for monitoring, then this extra step might be easy to do.  (Easier than remote control of the LED strip.)

Matt


> On Jul 17, 2017, at 4:25 PM, Justin Stevens <jrsteven at jlab.org> wrote:
> 
> Hi All,
> 
> As a reminder we have a DIRC meeting tomorrow at 1 pm.  The agenda can be found at https://halldweb.jlab.org/wiki/index.php/July_18,_2017_DIRC, please add items as necessary.
> 
> -Justin
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