Posted by
Craig Brideau on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Multi-photon-Laser-tp7581421p7581426.html
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Rather than relying on detected signal I prefer to measure the power out of
the objective, so you actually calibrate against power delivered to the
sample. You can get power meters now that fit under your objective, Lumen
Dynamics/Exfo and Thorlabs both sell these. I helped develop the Thor one,
so I'm not exactly unbiased here. @;-) However, my thinking is that this
method takes any non-linearities in your detection path out of the equation
so that your power slider setting is accurate to what you are delivering to
the sample.
With this method you stick the meter under the objective and get a linear
ramp of delivered power calibrated against slider position. The meter will
accept a drop of oil or water so you can use it with those types of lenses
if you want to be super accurate. As a side benefit, when you write a
paper and the reviewers ask how much power is on your sample, you will
already know.
Craig
On Thu, Dec 19, 2013 at 2:37 PM, Claire Brown <
[hidden email]>wrote:
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>
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>
> Thanks for your input Craig. Here is a bit more detail about our situation.
>
> Our Zeiss service people tell us they do the calibration using the standard
> PMTs in the microscope which only measure up to 700 because of the optical
> separation on the 710 (non filter based). So they do the calibration at 699
> nm but we want it to be linear out into the IR. We are trying to see if
> there is an issue with their calibration technique as it doesn't seem
> ideal.
>
> That being said when we measure the laser output at 700 nm or 800 nm are
> not
> linear. This is after two service visits and calibrations when the service
> people tell us all is fine. So it is unclear if it is a calibration or AOM
> issue.
>
> Any input would be appreciated.
>
> Sincerely,
>
> Claire
>