Damage Threshold for Objective Lenses with Pulsed Lasers

[V Hahn]

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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!

[Craig Brideau]

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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:

> *****
> 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]

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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:

> *****
> 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.
> *****
>
> 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

[Craig Brideau]

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*****

Fair point about general objective information being more freely available.
I did some poking around and you are correct; the curves for many high-end
lenses are available on the web now. The last time I looked into this was
several years ago when it was much harder to get this information.
Apparently my opinion was stale by a few years! @:-)

Craig

On Wed, Apr 5, 2017 at 11:12 AM, George McNamara <[hidden email]>
wrote:

> 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:
>
>> *****
>> 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.
>> *****
>>
>> 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
>
>

[Peter Rupprecht-2]

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Hi,
I would guess that it is not linear power, but peak power that is important for the damage threshold with two-photon imaging. But if I'm mistaken, I'd be glad to hear differing opinions.
However, there is work that is using not the typical Ti:Sa laser, but regenerative amplifiers, with slightly lower power, but lower repetition rate and therefore much higher peak power. 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.
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.html

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.
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/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!

   

[Craig Brideau]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
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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.html


I 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:
>
>
>  *****
> 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/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!
>
>
>