Posted by
Craig Brideau on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Damage-Threshold-for-Objective-Lenses-with-Pulsed-Lasers-tp7586701p7586707.html
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On Wed, Apr 5, 2017 at 12:08 PM, Peter Rupprecht <0000006d331a2665-dmarc-
[hidden email]> wrote:
> I have already seen an objective being damaged by such a laser system
> (although with the focus on the back aperture of the objective); btw, it
> also burned some holes in mirrors... A regular Ti:Sa installed in parallel
> with 10x higher average power did not do any damage to the objective.
>
I've managed to accidentally machine a tube lens (textured it like a golf
ball...) by focusing a Ti:Saph onto it years ago. As you say, pulse lasers
are particularly dangerous when focused as it is much easier to exceed the
material's energy threshold with a pulse.
Some early examples for such a system: Two-photon imaging to a depth of
> 1000 µm in living brains by use of a Ti:Al2O3 regenerative amplifier (no
> access from my side, so I cannot tell the details)
> Or
http://www.nature.com/neuro/journal/v14/n8/full/nn.2879.htmlI noted a number of new OPA-based imaging laser sources at Photonics West
this year. I suspect such high-energy sources will become increasingly
utilized for 2P deep imaging. I also anticipate more damaged objectives.
@:-) My own OPA can sometimes 2P excite the bleach in white paper without
requiring any sort of focus; the collimated beam waist is energetic enough.
> If people could hit their objectives with those peak power, the highest
> power of a regular Ti:Sa should be fine as well (unless heating plays a
> major role). Of course, this is only my guessing.
>
Agreed as long as the beam never comes to a tight focus.
Craig
> Best,Peter
>
>
>
> V Hahn <
[hidden email]> schrieb am 16:16 Mittwoch, 5.April 2017:
>
>
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>
> Hello,
>
> I was wondering whether some of you have a coarse idea of the damage
> threshold of objective lenses when being used with pulsed laser sources.
>
> I found some entries in this mailing list:
> [1]
https://lists.umn.edu/cgi-bin/wa?A2=CONFOCALMICROSCOPY;72b053a8.1001> refers to cw laser.
> [2]
http://confocal-microscopy-list.588098.n2.nabble.com/objecti> ve-lens-laser-damage-td7585244.html
> refers to tirf configuration, where the laser is focused at the back focal
> plane.
>
> more specifically, my application is two-photon imaging with a Leica HC PL
> APO 100x/1.40 Oil CS2 with a collimated beam at the backfocal plane. We use
> a Ti:Sa Laser (780 nm, 140fs, 80MHz, max 3.5W). I am mostly concerned about
> heating, epoxy detachement and burning at the front meniscus lens. In
> literature I found people using up to 500mW using this configuration...
>
> Does someone have a transmission curve for these lenses?
>
> Thank you!
>
>
>