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> A couple of questions for the list:
>
> 1, We are currently in the process of buying a new laser power meter that
> will
> primarily be used to check the general stability and power output of the
> laser
> lines of our CLSMs. Have anybody recently bought a power meter after
> considering some of currently offered products (like the Coherent LabMax
> TOP, Newport 1918-R, GigaHertz PT-9610 and Ophir Vega). Which one did
> you choose and why?

Good afternoon, Martin,

we have some by Coherent, Melles Griot, Standa, Spectra Physics...
Fine all (and some are OEM products just having received a selling
company's label). If you want to record the laser power over long periods
of time, it might be a good idea to check that your measurement amplifier
provides a BNC cabled output, which you can feed into a recorder (LabView
device or something like that).

>
> 2, Are there any commercially available laser meter sensors that will
> allow us
> to measure the actual laser light output from a high NA (NA>1) water or
> oil
> immersion objective?

Coherent "Laser Check". Fine device, indeed! Always make sure you adjust
it for the proper wavelength. The versions I have are not suitable for
lambda<400nm.

NOTE! When you measure the power in the focal region of any immersion
objective, you should

a)
Assume that the immersion medium does not absorb a noticeable faction of
the power (if it does, then it is "bio-dirty" with non dissolved particles
or with small air bubbles, and it should not be, not even for biological
measurements),

b)
Make sure the objective front lens really is clean and wiped for the power
measurement.

Concerning b): It is, to my mind, not a good idea to put any water or oil
between the objective front lens and the detector unit. It just soils the
detector unit and, given a), should not make any difference. However, if
you have some rest drops of oil or water on the objective but at the same
time do NOT establish an immersion like contact to the detector, then you
will lose a considerable amount of power due to the reflection of light at
the surface oil-air or water-air at the lower ends of the drops.


Best wishes,

Johannes


>
> Martin
>


-- 
P. Johannes Helm

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