Laser power meter and sensor

[Richard Cole]

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Dear All,

 

Immersion lens, especially high NA ones:  Although not simple to setup, the
most accurate way to measure transmittance/power is to use two objectives
focused on a coverslip sandwich.   The position in XY&Z can be tweaked to
give the maximum power.  Infinity corrected lens this is easier.  I would be
happy to provide more details off line.

 

Happy imaging

 

Rich

 

Richard Cole
Research Scientist V
Director: Advanced Light Microscopy Core Unit
Wadsworth Center

 

Research Assistant Professor
Dept. of Biomedical Sciences
School of Public Health State University of New York


P.O. Box 509 Albany N.Y. 12201-0509
518-474-7048 Phone
518-474-4430 Fax

 

Email  <mailto:[hidden email]> [hidden email]

Website  <http://www.wadsworth.org/cores/alm/index.htm>
www.wadsworth.org/cores/alm/index.htm

 

 

 

[John Oreopoulos]

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Richard, that sounds like an interesting protocol. I'd like to learn about it.

John Oreopoulos

On 2013-03-13, at 9:41 AM, Richard Cole <[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Dear All,
>
>
>
> Immersion lens, especially high NA ones:  Although not simple to setup, the
> most accurate way to measure transmittance/power is to use two objectives
> focused on a coverslip sandwich.   The position in XY&Z can be tweaked to
> give the maximum power.  Infinity corrected lens this is easier.  I would be
> happy to provide more details off line.
>
>
>
> Happy imaging
>
>
>
> Rich
>
>
>
> Richard Cole
> Research Scientist V
> Director: Advanced Light Microscopy Core Unit
> Wadsworth Center
>
>
>
> Research Assistant Professor
> Dept. of Biomedical Sciences
> School of Public Health State University of New York
>
>
> P.O. Box 509 Albany N.Y. 12201-0509
> 518-474-7048 Phone
> 518-474-4430 Fax
>
>
>
> Email  <mailto:[hidden email]> [hidden email]
>
> Website  <http://www.wadsworth.org/cores/alm/index.htm>
> www.wadsworth.org/cores/alm/index.htm
>
>
>
>
>
>

[James Jonkman]

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Hi, Martin.  Nearly any of these power meters will do, but I agree that these
measurements should be limited to dry objectives, leaving you to estimate the
transmission of the high-NA objectives.  Your application might be different
than mine, but for me my main concern was laser instabilities on many of our
confocals - it turned out to be more common than i thought, and i and my
users were oblivious to thes problems until I started measuring it.  I'm less
interested in the absolute power at the sample for the high-NA lenses, and it's
just too difficult to measure even if one of my users wanted to know it, so I
just help them to estimate it.

As per the best one to buy, my vote would be for the X-Cite XR2100 with
sensor XP750, which seems to be the only power meter designed specifically
for microscopy.  It may seem like a small point, but having the sensor in the
shape of a microscope slide makes it just that much easier to mount on the
scopes.  For the inverted scopes (and most of mine are inverted) I like that
they have a target on the back of the sensor that i can aim my brightfield
lamp at, so i know i'm in the middle of the objective.  Also, for my widefield
scopes, it has an extra sensor built into the power meter controller itself that
lets me plug in my liquid light guides (X-Cite, Zeiss HXP, etc.) and measure the
power of those lamps directly and very quickly.  And i like that i can store my
favourite wavelengths that correspond to my laser lines - makes it faster to
switch between them.

I have 2 other power meters (Coherent, Thorlabs), but i only use the X-Cite
now.  I must make a small disclaimer, though.  Lumen Dynamics is just down
the road from me, so they had me test-drive the power meter and wanted me
to write an app note.  I couldn't believe how many of my lasers were all over
the place, once i started measuring them!  When i saw this, i gladly bought
the power meter (they gave me a 25% discount for my efforts with the app
note, so hence the small financial disclaimer).  Actually, i operate 2 sites and i
just bought a second one so i'm putting my money where my mouth is.

I don't have a good sense of how the X-Cite compares price-wise to other
power meters, but for microscopists I think this one makes a lot of sense.

Cheers,
James