Re: Damage Threshold for Objective Lenses with Pulsed Lasers

Posted by George McNamara on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Damage-Threshold-for-Objective-Lenses-with-Pulsed-Lasers-tp7586701p7586704.html

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Hi Craig,

I disagree with your claim:

"The transmission curves of these lenses are apparently Top Secret
information as most vendors will not give them out."

For example, four curves are very close to the top of

https://micro.magnet.fsu.edu/primer/anatomy/imagebrightness.html

Zeiss objective lens assistant page
https://www.micro-shop.zeiss.com/index.php?s=474186562daf1&l=en&p=de&f=o

then choosing one of the lenses

Objective W Plan-Apochromat 20x/1.0 DIC M27 75mm
421452-9800-000

https://www.micro-shop.zeiss.com/index.php?s=82544385827b58&l=en&p=de&f=o&a=v&m=s&id=421452-9800-000

and clicking on the Transmittance curve graph

https://www.micro-shop.zeiss.com/index.php?s=82544385827b58&l=en&p=de&f=o&a=v&m=s&id=421452-9800-000&o=0&st=1

shows a curce 300 to 1110+ nm.

I (probably) have seen curves online for Leica, Nikon and Olympus as
well -- while unfortunately not in numeric format (I was looking circa
in 2005-2006 for PubSpectra project), your claim of Top Secret is
clearly wrong.

George


On 4/5/2017 11:45 AM, Craig Brideau wrote:

> *****
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> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> 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:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> Post images on http://www.imgur.com and include the link in your posting.
>> *****
>>
>> 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!
>>

--


George McNamara, PhD
Houston, TX 77054
[hidden email]
https://www.linkedin.com/in/georgemcnamara
https://works.bepress.com/gmcnamara/75/
http://www.ncbi.nlm.nih.gov/myncbi/browse/collection/44962650