*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
Post images on http://www.imgur.com and include the link in your posting.
*****

I don't know what Nikon does, but I did pull apart one commerical MPM
scope that uses an 8 bit value for PMT gain.  Inside was a DAC wired
up to the gain control line on the integrated Hamamatsu power supply.
Adjusting the 8 bit value changed the 0.4-1.2 volt DAC output, which
in turn adjusted the output of the internal DC-DC supply via a gain
line on the PMT.

At very least though, that 8 bit value must be controlling the PMT
voltage, either via signaling to an internal power supply, or by
controlling an external one.

Mike

On Wed, Oct 26, 2016 at 9:45 AM, Weber, Michael
<[log in to unmask]> wrote:
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Hi Mike,
>
> Thanks for your reply! I still don’t get it, though. When changing the 8 bit value in Elements, we are directly controlling the PMT power supply? I assume that other manufacturers are converting that value into voltage. From what I know, a 50V increase at the PMT corresponds to a two-fold increase in gain. How would that compare to the 8 bit value?
>
> I don’t know the model of our GaAsP detectors, all I could find are the QE curves:
>
> http://www.nikon.com/products/microscope-solutions/lineup/confocal/a1/detector.htm
>
> Michael
>
>> On Oct 25, 2016, at 4:18 PM, Michael Giacomelli <[log in to unmask]> wrote:
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> Post images on http://www.imgur.com and include the link in your posting.
>> *****
>>
>>> In NIS Elements, the gain/HV range is displayed in 8 bit (0-255) rather than voltage. Why is that?
>>
>> One common reason for this is that the PMT uses an integrated high
>> voltage power supply with an external gain control line.  In this
>> case, the gain is usually specified (and exponential with that 8 bit
>> value), but the actual PMT voltages are not (unless you can get access
>> to the documentation for the internal power supply).
>>
>> Do you know the model of your GaAsP PMT?
>>
>> Mike
>>
>> On Tue, Oct 25, 2016 at 3:49 PM, Weber, Michael
>> <[log in to unmask]> wrote:
>>> ***** To join, leave or search the confocal microscopy listserv, go to:
>>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy Post images on
>>> http://www.imgur.com and include the link in your posting. *****
>>> Dear list,
>>>
>>> I’ve got a question regarding the gain / high voltage setting when running
>>> the Nikon A1R point scanning confocal. In NIS Elements, the gain/HV range is
>>> displayed in 8 bit (0-255) rather than voltage. Why is that? Other
>>> manufacturers simply display the voltage (e.g. 0-1250 V). Is there a way to
>>> see the according voltage, or can it be calculated somehow? What’s the
>>> recommended range for PMT and GaAsP detectors? I couldn’t really get
>>> convincing information about that. Maybe someone knows more about it? I’d
>>> appreciate any input!
>>>
>>> Best,
>>> Michael
>>> _____________
>>>
>>> Dr. Michael Weber
>>> Advanced Microscopy Fellow
>>> Harvard Medical School
>>> 240 Longwood Ave, LHRRB 113, Boston, MA 02115
>>> http://nic.med.harvard.edu
>>>
>
>