Re: 405 laser intensity at the objective is 0.15% of actually intensity ... is this normal?

Posted by Zdenek Svindrych-2 on
URL: http://confocal-microscopy-list.275.s1.nabble.com/405-laser-intensity-at-the-objective-is-0-15-of-actually-intensity-is-this-normal-tp7587264p7587291.html

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Also, some single mode fibers are actually not single mode at 405 nm. The
higher modes won't be useful for fluorescence excitation in a confocal
microscope... So just check the far filed pattern from your fiber when
aligning the 405 line to make sure you're only coupling to the TEM(0,0) mode
- it should be nice gaussian when you point the bare fiber at a sheet of
common white (fluorescent ) paper.
--
Zdenek Svindrych, Ph.D.
W.M. Keck Center for Cellular Imaging (PLSB 003)
Department of Biology,University of Virginia
409 McCormick Rd, Charlottesville, VA-22904
http://www.kcci.virginia.edu/
tel: [phone]

---------- Původní e-mail ----------
Od: Peter Brunt <[hidden email]>
Komu: [hidden email]
Datum: 11. 9. 2017 10:45:05
Předmět: Re: 405 laser intensity at the objective is 0.15% of actually
intensity ... is this normal?
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Hi Emmanuel,
For singlemode fibre coupling across multiple wavelengths ranging from 405-
642nm I'd typically expect >60% coupling efficiency for all lines in the
worst case. For 405nm, 488nm and 561nm I'd actually expect closer to ~70% on
the basis that most fibre coupling systems (industry wide) aren't entirely
achromatic and the closer the wavelengths, the easier it is to adjust the
coupling optics to maximise the efficiency.

Still, if we assume there is still some loss on the dichroics, you should
still expect ~54% average power out of the fibre. I think there is a good
chance your lasers / fibre coupler need realigning. This is somewhat
evidence by the fact that your coupling seems to be biased towards 561nm.

I hope this helps.


Pete Brunt

AVR Optics
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