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Thanks all for your helpful suggestions. For the purposes of this
experiment, we kept it simple (air objective, non-resonant) and reported a
range of mW/micron2 values. If the user does require greater precision and
accuracy in the future, I'll know how to approach the question.
Cheers!
Jolien
---------------------------------------------
Jolien Tyler, Ph.D.
University of Colorado
MCD Biology
347 UCB
Boulder, CO 80309
303-492-5955 (office)
http://mcdb.colorado.edu/facilities/lmcf/index.html
On Tue, Aug 18, 2015 at 11:47 AM, Craig Brideau <[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 Ian, I actually helped design the low-power version of that power meter
> head with Pina Colarusso. The S175C is for higher-power applications, while
> the original S170C is for lower power. The 170 is more accurate for sub-mW
> powers typical of confocal systems. The higher-power one is good for power
> for certain non-linear processes. Both the 175 and 170 are oil and water
> compatible, and I found using the proper immersion medium on the sensor was
> especially critical for oil lenses.
>
> Craig Brideau
>
> On Tue, Aug 18, 2015 at 3:38 AM, Ian Dobbie <[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.
> > *****
> >
> > Johannes Helm <[log in to unmask]> writes:
> >
> > > *****
> > > 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 Jolien,
> > >
> > > it is not an easy task to measure the power in the focal region of the
> > > objective "exactly" and the job gets even more complicated if you want
> > > to determine the power "per pixel" in the way you describe.
> > >
> > > 1)
> > > In general:
> > >
> > > a)
> > > Unless you have a dry objective, some power will, even - and
> > > particularly - in case of "perfect" or "quasi perfect" alignment - be
> > > "lost" when measuring the laser power with the detector placed under
> > > the objective because of total reflection (unless you could "immerse"
> > > the sensitive area of the power meter in the immersion medium, which
> > > most probably would be bad for the power meter). In other words: If
> > > you have an oil immersion objective and do not have any oil on its
> > > front lens, the "outer ring" of light incident from the inside of the
> > > objective to the front lens will be lost due to total reflection (will
> > > be "sent back into the objective").
> >
> > Thorlabs have a nice new power meter head.
> >
> > http://www.thorlabs.de/thorproduct.cfm?partnumber=S175C
> >
> > It is in a slide form factor with a glass coverslip and then a
> > scattering index matched media before the sensor itself. This should
> > give you accurate readings even with a oil immersion objective. No use
> > for a 1.6 NA TIRF objective but good for normal oil objectives.
> >
> > Ian
> >
>
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