Posted by
Steffen Dietzel on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Safe-to-run-multiphoton-laser-at-100-power-for-overnight-continuous-imaging-tp7588726p7588734.html
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Am 26.09.2018 um 11:00 schrieb Christian Wilms:
> In line with what Craig said, I would suggest you measure the power at the sample plane, as well as the power going into the actual microscope scanhead (if you can access that point). This will give you an idea of what you are actually dealing with.
But (as far as I know) the usual power meters only give an accurate
reading with light that falls orthogonally on their surface. So with a
high NA objective, at the sample plane the measured value would be
substantially less than the actual power and you only get a 'minimal
estimate'. Some people use a 10x therefore, which has a low NA. Or you
can measure without objective to get a maximum estimate, disregarding
the less-than-100%-transmission of the objective (and the cut-off that
does not enter the objective). The true value then should be between the
two estimates.
Apparently it is virtually impossible to do this measurement at the
sample plane accurately with the usual tools.
Steffen
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Steffen Dietzel, PD Dr. rer. nat
Ludwig-Maximilians-Universität München
Biomedical Center (BMC)
Head of the Core Facility Bioimaging
Großhaderner Straße 9
D-82152 Planegg-Martinsried
Germany
http://www.bioimaging.bmc.med.uni-muenchen.de