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G'day Ohkyung,
I'm only new to the FV1000, so if others disagree please correct me.
HV refers to High Voltage and is the number of volts applied to the PMT.
To add to your confusion this is sometimes also called "Gain" or "PMT
Gain" by other manufacturers.
As you and others have pointed out the FV1000 also has a "Gain"
function, and this is an amplification of the PMT signal as previously
pointed out.
Generally speaking I think it is preferable to have this amplification
gain switched off (ie. set to 1), and use only the HV to increase
signal. I presume as the Amp. Gain feature is offered by Olympus, there
must be situations where if the signal strength is low, and if
increasing the HV further results in more noise (Lower signal/noise
ratio (S/N) ), then using some Amplifier gain and a little less PMT HV
may produce a better S/N ratio (ie. a less noisy image). I have not yet
found that set of circumstances. Can anyone comment in what set of
circumstances the Amp. Gain becomes useful?
Cheers
Steve
Stephen H. Cody
Microscopy Manager
Central Resource for Advanced Microscopy
Ludwig Institute for Cancer Research
PO Box 2008 Royal Melbourne Hospital
Victoria, 3050
Australia
Tel: 61 3 9341 3155 Fax: 61 3 9341 3104
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-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]] On
Behalf Of Barry O'Brien
Sent: Thursday, 4 September 2008 8:07 AM
To: [log in to unmask]
Subject: Re: FV1000 : HV vs gain
Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
On the FV1000 the gain is applied after the A/D conversion. This becoms
evident if the histogram is studied closely on images collected at gain
settings higher than 1.0. We confirmed this through dialogue with the
local consultant and the manufacturer.
I understand that other makes have a gain stage prior to this step, as
Mario suggests.
Regards,
Barry
At 05:16 a.m. 4/09/2008, you wrote:
>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>Ohkyung, James,
>
>I admittedly have never used an FV1000, but I am surprised that the HV
>refers to current rather than PMT operating voltage (which drives the
>current). Current generated in a PMT is exponentially sensitive to the
>voltage applied and each tube will have an optimal voltage (usually
>several hundred) that gives a linear current output over a range of
light
>intensities. Gain, on the other other hand, would be normally pertinent
to
>amplification of the PMT current output to something suitable for the
A/D
>converters that digitize the signal.
>
>A clarification would helpful. Thanks,
>
>Mario
>
>>Search the CONFOCAL archive at
>>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>>
>>Hello Ohkyung,
>>The HV is the current supplied to the PMT.
>>The Gain is the amplification of the signal from the PMT.
>>hope this helps.
>>best
>>James Beals
>>[log in to unmask]
>>734.936-2051
>>
>>205 Zina Pitcher Place
>>2038 MBNI
>>Molecular and Behavioral Neuroscience Institute
>>University of Michigan
>>Ann Arbor, Mi
>>48109
>>
>>
>>
>>
>>
>>On Sep 3, 2008, at 11:28 AM, Ohkyung Kwon wrote:
>>
>>>Search the CONFOCAL archive at
>>>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>>>
>>>Hello listers,
>>>
>>>I am wondering the difference between HV and gain in the operational
>>>software of FV1000. Please educate me. Thanks very much in advance.
>>>
>>>Ohkyung
>
>
>--
>_______________________________________________________________________
_________
>Mario M. Moronne, Ph.D.
>
>[log in to unmask]
>[log in to unmask]
>[log in to unmask]
Dr Barry O'Brien
Dept of Biological Sciences,
University of Waikato
Private Bag 3105
HAMILTON
New Zealand
Fax 0064 7 838 4324
Phone 0064 7 838 4179
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