Posted by
Craig Brideau on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Damage-Threshold-for-Objective-Lenses-with-Pulsed-Lasers-tp7586701p7586703.html
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The transmission curves of these lenses are apparently Top Secret
information as most vendors will not give them out. Some will give you the
absorption value at specific wavelengths if you ask. Part of this depends
on the back aperture of the objective and the magnification. A large back
aperture helps you avoid burning the input of the objective, while a
low-magnification lens typically has less glass and thus fewer
surfaces/internal optics to absorb the light. In general, physically larger
lenses will be able to handle more power. My own experience is that a
typical 2-photon lens with coatings for the NIR can handle >500mW, although
I generally try to keep it under this value to avoid pushing my luck. You
can also get lenses specifically designed for laser machining that can
handle watts of power and I've had limited success with such a lens in the
past. (Mitutoyo NIR HR 50x air; note it is not well corrected for
biological samples but works great on surface imaging)
Craig
On Wed, Apr 5, 2017 at 8:15 AM, V Hahn <
[hidden email]> wrote:
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>
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy> Post images on
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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/> objective-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!
>