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Hi,

the power going through the objectives depends heavily on the amount and
type of glass used.

If you put a powersensor at the sample plane you should check that the light
doesn't overfill the aperture of the sensor. Otherwise you would get wrong
readings at the meter.

Best
Roland


Roland Krüppel
Life & Brain Center
AG Prof. Beck - Experimental Epileptology and Cognition Research
University of Bonn Medical Center
Sigmund-Freud Str. 25
53127 Bonn
Tel.: 49-228-6885 279 (Office) / 293 (Lab)
Fax.: 49-228-6885 294 

> -----Original Message-----
> From: Confocal Microscopy List 
> [mailto:[log in to unmask]] On Behalf Of John Runions
> Sent: Wednesday, December 07, 2005 5:16 PM
> To: [log in to unmask]
> Subject: laser output power
> 
> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
> 
> Can someone provide me with a short lesson on measuring laser 
> output power at the specimen plane?  The Zeiss man was here 
> yesterday and he kindly made a series of measurements for me. 
>  We set the laser current to 6.5 amps and measured the 488 
> line of a 25 mW argon laser with both 10x and 100x 
> objectives.  Output varied as I expected as transmission 
> percentage was adjusted from 100 down to 0.1.  My question 
> is, why is the power so much higher coming through the 10x 
> objective than through the 100x at any given setting, e.g. 
> 0.754 mW 10x but only 0.062 mW 100x at the same transmission 
> setting?  Is the reading from the meter integrated over the 
> whole field of view?  The reason I ask is that I, perhaps 
> naively, expected the power to be higher coming through the 
> 100x objective.  John.
> -- 
> 
> *********************************
> C. John Runions, Ph.D.
> School of Biological and Molecular Sciences Oxford Brookes 
> University Oxford, UK
> OX3 0BP
> 
> email: [log in to unmask]
> phone: +44 (0) 1865 483 964
> 
>