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Dear Karl,

Guy is correct here.  I've checked our 4 PMTs against bluish through deep
red fluorescence, and PMT1 is definitely most sensitive in the blue, PMT2
in green-yellow, PMT3 in orange-red and PMT4 in red through long red

Another quirk to be aware of is that the dichroic filters let through
different % of laser light.  So the intensity of the 488 line coming
through RSP500, DD488/543 and TD488/543/633 is different for each.

cheers,
Rosemary

>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>Quoting Karl Garsha <[log in to unmask]>:
>
>> Search the CONFOCAL archive at
>> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>>
>> Greetings,
>> Has anybody determined a benchmark for evaluating PMT sensitivity on the
>> SP-2 platform?  I've recently discovered that our PMT 1 is showing
>> roughly 30% of the sensitivity of PMT 3 and PMT 2 is showing 65% of the
>> sensitivity of PMT 3 (at either end of the spectrum).  This is a little
>> alarming and I would like to determine whether PMT 3 is in fact
>> performing well or if the sensitivity is down for it as well.  Thanks in
>> advance for any suggestions.
>
>Depending on your system they may well be different types of PMT -
>I think our system has 1 bi-alkali and the others multi-alkali.  So
>check that first.  Generally one would expect that more blue-sensitivity
>is desirable on PMT1 and more red on PMT3.  The other thing to remember
>is that voltage response may vary and a more accurate control is
>obtainable signal to noise ratio.
>
>                                                     Guy
>
>--
>Associate Professor Guy Cox
>Electron Microscope Unit, F09
>University of Sydney NSW 2006
>+61 2 9351 3176


Rosemary White
Microscopy Centre
CSIRO Plant Industry, Canberra
phone  6246 5475 or 0402 835 973
email   [log in to unmask]