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The graphs at http://cammer.net/historical/aif/instructions/fluor-ref-slides/40X.htm from more than ten years ago show a quick comparison of the importance of measuring throughput at the specific wavelengths you are using.  The graph only shows relative throughputs for the 40X objectives we had in the lab at the time, not measured mW, but makes the point.

Now to measure power we put a light meter probe where the sample would be.  With high NA objectives we measure through a glass slide or coverslip with oil.

Regards,

Michael


-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]] On Behalf Of Richard Cole
Sent: Monday, July 01, 2013 9:01 AM
To: [log in to unmask]
Subject: Re: How to calculate an estimate of power density for laser illumination ?

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It is imperative to include the objective lens in any power measurement (completely agree with others responding).  The most accurate method is to use two similar objectives, both focused on the same area but from opposite sides, measuring the power at the back aperture of the second objective (infinite corrected objective make this much easier).  If you want more info just shoot me an email.

 

Cheers

 

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 

 

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www.wadsworth.org/cores/alm/index.htm

 

 


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