>I  would like to purchase a power meter and probe for use on our Bio-Rad
>MRC-1024 which has a 15mW Kr/Ar cw laser.  From Coherent I am looking at
>the LaserMate-Q meter and from Molectron I am looking at the PM-500D
>meter.   I want to be able to check the final power coming through the
>objective to the specimen.  I am only interested in single photon
>continuous wave at the moment.
>        Do  members of the list have suggestions for selection of the best
>meter and probe for use with this laser and up to about 1W power?  Do any
>of the probes allow you to focus the objective onto the faceplate? Or are
>you modifying the probes?  Thanks for any guidance.
>
>
>Ken Orndorff
>H.C. Englert Cell Analysis Lab
>Dartmouth Medical School
>Borwell 383 West
>One Medical Center Drive
>Lebanon, NH  03756
>
>603-650-7661 phone
>603-650-6130  FAX
>[log in to unmask]

Hi Ken,

I list below a system that I bought some years ago that seems good as far
as sensitivity goes. It also have a Paddle sensor that is good for looking
into smallish spaces.  Other sensors are possible.

I am really responding to your comment about wanting to measure the light
coming out of your objective.  First of all, I think that this is a highly
commendable "objective".  However, because such light may be highly
convergent/divergent, it presents measurement problems of its own: light
approaching the sensor element a large angles may be lost by total internal
reflection at glass-air interfaces.

Of course you should "oil" any light sensor to the front element of an oil
objective.  However, this will not be effective if the "front surface of
your sensor" is actually a piece of glass that is separated by an air gap
from the silicon of the sensor itself.  Try to buy a sensor that doesn't
have such an air gap.  If you aren't sure, you will have to use another
lens (the condenser??) to make the light from the  objective parallel or
almost parallel to the optical axis before you can measure it reliably.
Otherwise you will only be measuring the light going through the low-NA
part of the objective.

By the way, comparing the "oiled" and "non-oiled" readings will tell you if
the objective BFP is really filled by the laser. If it isn't, you are not
operating at high NA.

Good luck,

Jim Pawley



I don't have any pecuniary interest in Newport and this info may be out of
date. It is listed for  reference only: as a starting point. I am not sure
that it works all the way to 1 Watt. But I can't imagine using that much
light in microscopy: more like welding!!


Newport Instruments (800-222-6440 x 408)

Model 1830 C Picowatt Digital Optical Power meter       $1,769
with 818-ST-CM sensor probe                                529

Total                                                   $2,298


Or if funds are short,

Model 1815C Optical Power Meter,                        $635
Model 818-ST sensor probe                               $396

Total                                                 $1,031

              ****************************************
Prof. James B. Pawley,    (on Sabbatical)       Ph.  61-2-9351-7548/2351
Room LG 10, Madsen Building, F-09,              FAX  61-2-9351-7682
University of Sydney, NSW, 2006 Australia       [log in to unmask]
Come to the 5th 3D Live-cell Microscopy Course, June 19-29, 2000, UBC, Canada.
Info and forms at: http://www.cs.ubc.ca/spider/ladic/course/bulletin.html
"A scientist is not one who can answer questions but one who can question
answers."       Theodore Schick Jr., Skeptical Enquirer, 21-2:39