Nikon A1R: gain / high voltage

[Weber, Michael]

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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

[Michael Giacomelli]

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>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
<[hidden email]> 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
>

[Weber, Michael]

*****
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*****

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 <[hidden email]> 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
> <[hidden email]> 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
>>

[Michael Giacomelli]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
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*****

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
<[hidden email]> 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 <[hidden email]> 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
>> <[hidden email]> 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
>>>
>
>