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

Posted by Craig Brideau 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-tp7587264p7587269.html

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Try measuring the power of all three lines using a different objective
lens. Many objectives are not designed to work below 450nm and so they
absorb considerably for lasers shorter than the blue. Also, remove the
objective lens and try measuring the power of the beam. You will probably
overfill your power meter, but you will be able to compare the relative
power between the three lines from what light does hit your sensor.

Craig

On Wed, Sep 6, 2017 at 1:28 PM, Emmanuel Levy <[hidden email]>
wrote:

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>
> Dear Peter,
>
> Thank you for this information.
>
> Are you running your lasers at full power?
>
>
> Yes we are.
>
>
> > What combiner are you using?
>
>
> It is a custom made combiner, from the company that assembled the
> microscope.
>
>
> > I can't comment so much on the power you have at your objective but on
> > your combiner side the values look low.  Going into a multi-mode fibre
> > should be like a barn door for your lasers so if we imagine a ~5% (x2)
> loss
> > due to combining optics and an ~80% coupling efficiency, you should still
> > be getting a ~72% average coupling efficiency into the fibre.  It sounds
> to
> > me like the setup may need to be realigned. If you still don't see an
> > improvement then one other possibility is that the 405nm laser has
> degraded
> > your fibre due to solarisation and the fibre needs replacing.
> >
>
> Thanks a lot for this info, I'll discuss it with the company.
>
> If there are other opinions, in particular regarding the loss between te
> fiber-output and the objective, I'd be glad to hear them.
>
> Best wishes,
>
> Emmanuel
>
>
>
>
>
> >
> > I hope this helps.
> >
> >
> > Kind Regards
> >
> > Pete Brunt
> >
>