two-photon absorption

[Martin Wessendorf-2]

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Dear List--

Is there a physicist out there who can offer an intuitive explanation of
how 2-photon absorption occurs?  I expect we all know that it isn't that
there isn't any half-excited state that allows one photon to boost an
electron half-way to the excited state, and the next photon to finish
the job.  My sense is that it has to do with time-energy uncertainty (a
la Heisenberg) but my quantum mechanics is elementary-school level.

Thanks!

Martin Wessendorf

--
Martin Wessendorf, Ph.D.                   office: [phone]
Assoc Prof, Dept Neuroscience                 lab: [phone]
University of Minnesota             Preferred FAX: [phone]
6-145 Jackson Hall, 321 Church St. SE    Dept Fax: [phone]
Minneapolis, MN  55455                    e-mail: [hidden email]

[Guy Cox-2]

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I'm sure Colin Sheppard reads this list, and he played with 2P a long time ago, so maybe he will comment.  Maybe Warren Zipfel will too.  I will just comment that if there is a 'half-way' electronic state available it increases the possibility (cross-section) of two-photon absorption - even though the electron never actually occupies that state!  That's quantum mechanics for you!

                                        Guy

Guy Cox, Honorary Associate Professor
School of Medical Sciences

Australian Centre for Microscopy and Microanalysis,
Madsen, F09, University of Sydney, NSW 2006

-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Martin Wessendorf
Sent: Monday, 7 April 2014 12:24 PM
To: [hidden email]
Subject: two-photon absorption

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*****

Dear List--

Is there a physicist out there who can offer an intuitive explanation of how 2-photon absorption occurs?  I expect we all know that it isn't that there isn't any half-excited state that allows one photon to boost an electron half-way to the excited state, and the next photon to finish the job.  My sense is that it has to do with time-energy uncertainty (a la Heisenberg) but my quantum mechanics is elementary-school level.

Thanks!

Martin Wessendorf

--
Martin Wessendorf, Ph.D.                   office: [phone]
Assoc Prof, Dept Neuroscience                 lab: [phone]
University of Minnesota             Preferred FAX: [phone]
6-145 Jackson Hall, 321 Church St. SE    Dept Fax: [phone]
Minneapolis, MN  55455                    e-mail: [hidden email]

[Marcus Knopp]

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As far as I know, the effect, on the one hand, depends on the timing of the subsequent photons to be absorbed. They have to reach a fluorophore within a short time interval of sub-femtoseconds to a few femtoseconds, i.e. quasi simultaneously. On the other hand, it depends on the symmetry of a fluorophore, which, I think, determines the transition matrix between energy levels. Then it all comes down to whether a transition is allowed or not by the selection rules, which constrain transition for example by the need to conserve an electron's angular momentum. What exactly is going on, I don't know (does anybody?), but one interpretation is indeed, that the first photon induces a transition from the ground state to a virtual excited state at an intermediate energy level (what's wrong with that? It's just a model). This is thought to be close to a real state that can be occupied according to the selection rules. The second photon carries the system from the virtual state to the final state, that originally might have been forbidden.

Best,
Marcus


-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Martin Wessendorf
Sent: Monday, April 07, 2014 4:24 AM
To: [hidden email]
Subject: two-photon absorption

*****
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*****

Dear List--

Is there a physicist out there who can offer an intuitive explanation of how 2-photon absorption occurs?  I expect we all know that it isn't that there isn't any half-excited state that allows one photon to boost an electron half-way to the excited state, and the next photon to finish the job.  My sense is that it has to do with time-energy uncertainty (a la Heisenberg) but my quantum mechanics is elementary-school level.

Thanks!

Martin Wessendorf

--
Martin Wessendorf, Ph.D.                   office: [phone]
Assoc Prof, Dept Neuroscience                 lab: [phone]
University of Minnesota             Preferred FAX: [phone]
6-145 Jackson Hall, 321 Church St. SE    Dept Fax: [phone]
Minneapolis, MN  55455                    e-mail: [hidden email]

[Chen, De (NIH/NCI) [C]]

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To my knowledge, one photon excitation is linear optical process (dipole excitation, which is proportional to light intensity I), while two photon excitation is nonlinear (quadrupole excitation, proportional to I^2) ; In two photon absorption, an intermittent energy level close to one photon resonance will enhance the two photon excitation depending on the offset from the resonance energy level. Two photon excitation requires high laser power to excite. Short pulsed laser can provide the required high enough peak power to excite with two photon. Forbidden in dipole excitation is allowed in quadrupole excitation.

Reference:
   "The Principles of Nonlinear Optics" Y. R. Shen, 1984 | ISBN-10: 0471889989 | ISBN-13: 9780471889984
 
________________________________________
From: Marcus Knopp [[hidden email]]
Sent: Monday, April 07, 2014 5:53 AM
To: [hidden email]
Subject: Re: two-photon absorption

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*****

As far as I know, the effect, on the one hand, depends on the timing of the subsequent photons to be absorbed. They have to reach a fluorophore within a short time interval of sub-femtoseconds to a few femtoseconds, i.e. quasi simultaneously. On the other hand, it depends on the symmetry of a fluorophore, which, I think, determines the transition matrix between energy levels. Then it all comes down to whether a transition is allowed or not by the selection rules, which constrain transition for example by the need to conserve an electron's angular momentum. What exactly is going on, I don't know (does anybody?), but one interpretation is indeed, that the first photon induces a transition from the ground state to a virtual excited state at an intermediate energy level (what's wrong with that? It's just a model). This is thought to be close to a real state that can be occupied according to the selection rules. The second photon carries the system from the virtual state to the final state, that originally might have been forbidden.

Best,
Marcus


-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Martin Wessendorf
Sent: Monday, April 07, 2014 4:24 AM
To: [hidden email]
Subject: two-photon absorption

*****
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*****

Dear List--

Is there a physicist out there who can offer an intuitive explanation of how 2-photon absorption occurs?  I expect we all know that it isn't that there isn't any half-excited state that allows one photon to boost an electron half-way to the excited state, and the next photon to finish the job.  My sense is that it has to do with time-energy uncertainty (a la Heisenberg) but my quantum mechanics is elementary-school level.

Thanks!

Martin Wessendorf

--
Martin Wessendorf, Ph.D.                   office: [phone]
Assoc Prof, Dept Neuroscience                 lab: [phone]
University of Minnesota             Preferred FAX: [phone]
6-145 Jackson Hall, 321 Church St. SE    Dept Fax: [phone]
Minneapolis, MN  55455                    e-mail: [hidden email]

[John Oreopoulos]

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*****

If you're into quantum mechanical calculations, there is actually a fairly good derivation of the 2-photon process here at this link:

http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Electronic_Spectroscopy/Two-photon_absorption

Cheers,


John Oreopoulos
Staff Scientist
Spectral Applied Research Inc.
A Division of Andor Technology
Richmond Hill, Ontario
Canada
www.spectral.ca

On 2014-04-07, at 8:35 AM, Chen, De (NIH/NCI) [C] 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.
> *****
>
> To my knowledge, one photon excitation is linear optical process (dipole excitation, which is proportional to light intensity I), while two photon excitation is nonlinear (quadrupole excitation, proportional to I^2) ; In two photon absorption, an intermittent energy level close to one photon resonance will enhance the two photon excitation depending on the offset from the resonance energy level. Two photon excitation requires high laser power to excite. Short pulsed laser can provide the required high enough peak power to excite with two photon. Forbidden in dipole excitation is allowed in quadrupole excitation.
>
> Reference:
>   "The Principles of Nonlinear Optics" Y. R. Shen, 1984 | ISBN-10: 0471889989 | ISBN-13: 9780471889984
>
> ________________________________________
> From: Marcus Knopp [[hidden email]]
> Sent: Monday, April 07, 2014 5:53 AM
> To: [hidden email]
> Subject: Re: two-photon absorption
>
> *****
> 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.
> *****
>
> As far as I know, the effect, on the one hand, depends on the timing of the subsequent photons to be absorbed. They have to reach a fluorophore within a short time interval of sub-femtoseconds to a few femtoseconds, i.e. quasi simultaneously. On the other hand, it depends on the symmetry of a fluorophore, which, I think, determines the transition matrix between energy levels. Then it all comes down to whether a transition is allowed or not by the selection rules, which constrain transition for example by the need to conserve an electron's angular momentum. What exactly is going on, I don't know (does anybody?), but one interpretation is indeed, that the first photon induces a transition from the ground state to a virtual excited state at an intermediate energy level (what's wrong with that? It's just a model). This is thought to be close to a real state that can be occupied according to the selection rules. The second photon carries the system from the virtual state to the final state, that originally might have been forbidden.
>
> Best,
> Marcus
>
>
> -----Original Message-----
> From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Martin Wessendorf
> Sent: Monday, April 07, 2014 4:24 AM
> To: [hidden email]
> Subject: two-photon absorption
>
> *****
> 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.
> *****
>
> Dear List--
>
> Is there a physicist out there who can offer an intuitive explanation of how 2-photon absorption occurs?  I expect we all know that it isn't that there isn't any half-excited state that allows one photon to boost an electron half-way to the excited state, and the next photon to finish the job.  My sense is that it has to do with time-energy uncertainty (a la Heisenberg) but my quantum mechanics is elementary-school level.
>
> Thanks!
>
> Martin Wessendorf
>
> --
> Martin Wessendorf, Ph.D.                   office: [phone]
> Assoc Prof, Dept Neuroscience                 lab: [phone]
> University of Minnesota             Preferred FAX: [phone]
> 6-145 Jackson Hall, 321 Church St. SE    Dept Fax: [phone]
> Minneapolis, MN  55455                    e-mail: [hidden email]

[Smith, Benjamin E.]

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*****

I find Paul Falstad's simulation helpful in visualizing energy state transitions.  The model shows how quantum state transitions can be thought of as continuous: http://www.falstad.com/qmatomrad/

Since virtual states are unmeasurable, two photon excitation can be thought of as a coupling process between the two photons and the induced dipole:  http://researchspace.auckland.ac.nz/bitstream/2292/433/2/02whole.pdf

The way I imagine it is as two separate yet simultaneous steps.  The first photon induces a dipole oscillation to a virtual state.  Effectively simultaneously, a second photon also induces a further dipole oscillation kicking the dipole all the way up to an observable energy state.  The key is that both photons need to act on the molecule simultaneously, or the "virtual state" dipole disappears before the next photon can induce any further energy.

An analogy would be trying to roll a boulder up onto a log.  Two people of equal strength set about the task of rolling over a boulder up onto a log.  Both people have enough strength to get the boulder to rock back and forth, but neither can get it up onto the log by themselves.  If one person tries to move the boulder, the boulder will rock back and forth, but the moment they stop, the boulder will come to a rest as though nothing had been done to it.  The rocking boulder can be thought of as a virtual state, where the boulder will drop back to its "ground state" the moment someone stops rocking it.  

However, two people decide to work together (this is like the coupling model).  They time their rocking together, and by doubling their effort, they are able to roll the boulder all the way over to the meta-stable state of being on top of the log.  The boulder will then reside atop the log for some time before dropping back down, emitting energy equal to both people's contribution, minus some energy due to friction an noise (just like two-photon emission).

The reason why two photon excitation needs to be thought of as a coupling process, is let's think about a third scenario.  Person A starts to rock the boulder.  Then, person A lets go of the boulder and then person B immediately continues rocking the boulder.  Then end result of this effort would be a rocking boulder, however, since A and B aren't acting on the boulder at the same time, they won't ever be able to transition the boulder up onto the log.

Finally, let's imagine a world where the boulder can only be measured based on it's height of the ground.  Rocking neither raises nor lowers the boulder, so it wouldn't be an observable state.  However, we know that the boulder would have had to have been rocked back and forth to get it up onto the log, so while we can't observe it, we know it must exist.

Hope this helps,
   Ben Smith

Benjamin E. Smith, Ph.D.
Samuel Roberts Noble Microscopy Laboratory
Research Scientist II
University of Oklahoma
Norman, OK 73019
E-mail: [hidden email]
Voice   405-325-4391
FAX  [phone]
http://www.microscopy.ou.edu/


________________________________________
From: Confocal Microscopy List [[hidden email]] on behalf of John Oreopoulos [[hidden email]]
Sent: Monday, April 07, 2014 8:06 AM
To: [hidden email]
Subject: Re: two-photon absorption

*****
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.
*****

If you're into quantum mechanical calculations, there is actually a fairly good derivation of the 2-photon process here at this link:

http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Electronic_Spectroscopy/Two-photon_absorption

Cheers,


John Oreopoulos
Staff Scientist
Spectral Applied Research Inc.
A Division of Andor Technology
Richmond Hill, Ontario
Canada
www.spectral.ca

On 2014-04-07, at 8:35 AM, Chen, De (NIH/NCI) [C] 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.
> *****
>
> To my knowledge, one photon excitation is linear optical process (dipole excitation, which is proportional to light intensity I), while two photon excitation is nonlinear (quadrupole excitation, proportional to I^2) ; In two photon absorption, an intermittent energy level close to one photon resonance will enhance the two photon excitation depending on the offset from the resonance energy level. Two photon excitation requires high laser power to excite. Short pulsed laser can provide the required high enough peak power to excite with two photon. Forbidden in dipole excitation is allowed in quadrupole excitation.
>
> Reference:
>   "The Principles of Nonlinear Optics" Y. R. Shen, 1984 | ISBN-10: 0471889989 | ISBN-13: 9780471889984
>
> ________________________________________
> From: Marcus Knopp [[hidden email]]
> Sent: Monday, April 07, 2014 5:53 AM
> To: [hidden email]
> Subject: Re: two-photon absorption
>
> *****
> 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.
> *****
>
> As far as I know, the effect, on the one hand, depends on the timing of the subsequent photons to be absorbed. They have to reach a fluorophore within a short time interval of sub-femtoseconds to a few femtoseconds, i.e. quasi simultaneously. On the other hand, it depends on the symmetry of a fluorophore, which, I think, determines the transition matrix between energy levels. Then it all comes down to whether a transition is allowed or not by the selection rules, which constrain transition for example by the need to conserve an electron's angular momentum. What exactly is going on, I don't know (does anybody?), but one interpretation is indeed, that the first photon induces a transition from the ground state to a virtual excited state at an intermediate energy level (what's wrong with that? It's just a model). This is thought to be close to a real state that can be occupied according to the selection rules. The second photon carries the system from the virtual state to the final state, that originally might have been forbidden.
>
> Best,
> Marcus
>
>
> -----Original Message-----
> From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Martin Wessendorf
> Sent: Monday, April 07, 2014 4:24 AM
> To: [hidden email]
> Subject: two-photon absorption
>
> *****
> 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.
> *****
>
> Dear List--
>
> Is there a physicist out there who can offer an intuitive explanation of how 2-photon absorption occurs?  I expect we all know that it isn't that there isn't any half-excited state that allows one photon to boost an electron half-way to the excited state, and the next photon to finish the job.  My sense is that it has to do with time-energy uncertainty (a la Heisenberg) but my quantum mechanics is elementary-school level.
>
> Thanks!
>
> Martin Wessendorf
>
> --
> Martin Wessendorf, Ph.D.                   office: [phone]
> Assoc Prof, Dept Neuroscience                 lab: [phone]
> University of Minnesota             Preferred FAX: [phone]
> 6-145 Jackson Hall, 321 Church St. SE    Dept Fax: [phone]
> Minneapolis, MN  55455                    e-mail: [hidden email]

[Feinstein, Timothy]

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*****

Would it be a gross oversimplification to think of the 2p effect as
analogous to rogue waves on the sea?  Those occur when multiple waves
temporarily match vector and frequency and their amplitudes add together.
The sea wave analogy may help to explain why 2p is so nonlinear, as a
DeepSee or Cameleon always produces a range of wavelengths yet two waves
need to precisely match in space, vector and wavelength in order to go
rogue.

I know that quantum mechanics has a lot more going on than sea waves
sloshing around a Newtonian world and tipping the Poseidon over, but I
wonder how deep this discussion needs to go.

When teaching (elementary) FRET I always talk about what physicists
understand but practitioners do not necessarily need to memorize
themselves.  e.g., deriving the sixth power law or explaining what exactly
gets Œtransferred¹ if not a photon.  And if it is not a photon they why
does polarization still work?  What did space look like before the big
bang?  And so on down a hole chasing a rabbit with a pocket watch.  Note
that I am not trying to sidetrack the thread, I just want to suggest that
we specify how far down we want-slash-need to go.  Allowing of course that
folks have different needs.

Cheers,


TF

Timothy Feinstein, Ph.D. | Confocal Manager
333 Bostwick Ave., N.E., Grand Rapids, Michigan 49503
Phone: [phone] | Email: [hidden email]







On 4/7/14, 10:20 AM, "Smith, Benjamin E." <[hidden email]> wrote:

>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEN
>8ogAJZQ&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalmic
>roscopy
>Post images on
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDBZ
>98ApdNQ&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>posting.
>*****
>
>I find Paul Falstad's simulation helpful in visualizing energy state
>transitions.  The model shows how quantum state transitions can be
>thought of as continuous:
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEw
>s8g8KPA&u=http%3a%2f%2fwww%2efalstad%2ecom%2fqmatomrad%2f
>
>Since virtual states are unmeasurable, two photon excitation can be
>thought of as a coupling process between the two photons and the induced
>dipole:  
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDBV
>4oQwLPA&u=http%3a%2f%2fresearchspace%2eauckland%2eac%2enz%2fbitstream%2f22
>92%2f433%2f2%2f02whole%2epdf
>
>The way I imagine it is as two separate yet simultaneous steps.  The
>first photon induces a dipole oscillation to a virtual state.
>Effectively simultaneously, a second photon also induces a further dipole
>oscillation kicking the dipole all the way up to an observable energy
>state.  The key is that both photons need to act on the molecule
>simultaneously, or the "virtual state" dipole disappears before the next
>photon can induce any further energy.
>
>An analogy would be trying to roll a boulder up onto a log.  Two people
>of equal strength set about the task of rolling over a boulder up onto a
>log.  Both people have enough strength to get the boulder to rock back
>and forth, but neither can get it up onto the log by themselves.  If one
>person tries to move the boulder, the boulder will rock back and forth,
>but the moment they stop, the boulder will come to a rest as though
>nothing had been done to it.  The rocking boulder can be thought of as a
>virtual state, where the boulder will drop back to its "ground state" the
>moment someone stops rocking it.
>
>However, two people decide to work together (this is like the coupling
>model).  They time their rocking together, and by doubling their effort,
>they are able to roll the boulder all the way over to the meta-stable
>state of being on top of the log.  The boulder will then reside atop the
>log for some time before dropping back down, emitting energy equal to
>both people's contribution, minus some energy due to friction an noise
>(just like two-photon emission).
>
>The reason why two photon excitation needs to be thought of as a coupling
>process, is let's think about a third scenario.  Person A starts to rock
>the boulder.  Then, person A lets go of the boulder and then person B
>immediately continues rocking the boulder.  Then end result of this
>effort would be a rocking boulder, however, since A and B aren't acting
>on the boulder at the same time, they won't ever be able to transition
>the boulder up onto the log.
>
>Finally, let's imagine a world where the boulder can only be measured
>based on it's height of the ground.  Rocking neither raises nor lowers
>the boulder, so it wouldn't be an observable state.  However, we know
>that the boulder would have had to have been rocked back and forth to get
>it up onto the log, so while we can't observe it, we know it must exist.
>
>Hope this helps,
>   Ben Smith
>
>Benjamin E. Smith, Ph.D.
>Samuel Roberts Noble Microscopy Laboratory
>Research Scientist II
>University of Oklahoma
>Norman, OK 73019
>E-mail: [hidden email]
>Voice   405-325-4391
>FAX  [phone]
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDBF
>59QAMNg&u=http%3a%2f%2fwww%2emicroscopy%2eou%2eedu%2f
>
>
>________________________________________
>From: Confocal Microscopy List [[hidden email]] on
>behalf of John Oreopoulos [[hidden email]]
>Sent: Monday, April 07, 2014 8:06 AM
>To: [hidden email]
>Subject: Re: two-photon absorption
>
>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEN
>8ogAJZQ&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalmic
>roscopy
>Post images on
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDBZ
>98ApdNQ&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>posting.
>*****
>
>If you're into quantum mechanical calculations, there is actually a
>fairly good derivation of the 2-photon process here at this link:
>
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEE
>roVoOPA&u=http%3a%2f%2fchemwiki%2eucdavis%2eedu%2fPhysical%5fChemistry%2fS
>pectroscopy%2fElectronic%5fSpectroscopy%2fTwo-photon%5fabsorption
>
>Cheers,
>
>
>John Oreopoulos
>Staff Scientist
>Spectral Applied Research Inc.
>A Division of Andor Technology
>Richmond Hill, Ontario
>Canada
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEx
>5pVtaZw&u=http%3a%2f%2fwww%2espectral%2eca
>
>On 2014-04-07, at 8:35 AM, Chen, De (NIH/NCI) [C] wrote:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>>
>>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDE
>>N8ogAJZQ&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalm
>>icroscopy
>> Post images on
>>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDB
>>Z98ApdNQ&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>>posting.
>> *****
>>
>> To my knowledge, one photon excitation is linear optical process
>>(dipole excitation, which is proportional to light intensity I), while
>>two photon excitation is nonlinear (quadrupole excitation, proportional
>>to I^2) ; In two photon absorption, an intermittent energy level close
>>to one photon resonance will enhance the two photon excitation depending
>>on the offset from the resonance energy level. Two photon excitation
>>requires high laser power to excite. Short pulsed laser can provide the
>>required high enough peak power to excite with two photon. Forbidden in
>>dipole excitation is allowed in quadrupole excitation.
>>
>> Reference:
>>   "The Principles of Nonlinear Optics" Y. R. Shen, 1984 | ISBN-10:
>>0471889989 | ISBN-13: 9780471889984
>>
>> ________________________________________
>> From: Marcus Knopp [[hidden email]]
>> Sent: Monday, April 07, 2014 5:53 AM
>> To: [hidden email]
>> Subject: Re: two-photon absorption
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>>
>>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDE
>>N8ogAJZQ&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalm
>>icroscopy
>> Post images on
>>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDB
>>Z98ApdNQ&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>>posting.
>> *****
>>
>> As far as I know, the effect, on the one hand, depends on the timing of
>>the subsequent photons to be absorbed. They have to reach a fluorophore
>>within a short time interval of sub-femtoseconds to a few femtoseconds,
>>i.e. quasi simultaneously. On the other hand, it depends on the symmetry
>>of a fluorophore, which, I think, determines the transition matrix
>>between energy levels. Then it all comes down to whether a transition is
>>allowed or not by the selection rules, which constrain transition for
>>example by the need to conserve an electron's angular momentum. What
>>exactly is going on, I don't know (does anybody?), but one
>>interpretation is indeed, that the first photon induces a transition
>>from the ground state to a virtual excited state at an intermediate
>>energy level (what's wrong with that? It's just a model). This is
>>thought to be close to a real state that can be occupied according to
>>the selection rules. The second photon carries the system from the
>>virtual state to the final state, that originally might have been
>>forbidden.
>>
>> Best,
>> Marcus
>>
>>
>> -----Original Message-----
>> From: Confocal Microscopy List
>>[mailto:[hidden email]] On Behalf Of Martin Wessendorf
>> Sent: Monday, April 07, 2014 4:24 AM
>> To: [hidden email]
>> Subject: two-photon absorption
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>>
>>http://scanmail.trustwave.com/?c=129&d=zrTC0wJ3Btfng3o6Ki8VL3Twis07aGkKBI
>>yvzD1R-A&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalm
>>icroscopy
>> Post images on
>>http://scanmail.trustwave.com/?c=129&d=zrTC0wJ3Btfng3o6Ki8VL3Twis07aGkKBN
>>munjcFqA&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>>posting.
>> *****
>>
>> Dear List--
>>
>> Is there a physicist out there who can offer an intuitive explanation
>>of how 2-photon absorption occurs?  I expect we all know that it isn't
>>that there isn't any half-excited state that allows one photon to boost
>>an electron half-way to the excited state, and the next photon to finish
>>the job.  My sense is that it has to do with time-energy uncertainty (a
>>la Heisenberg) but my quantum mechanics is elementary-school level.
>>
>> Thanks!
>>
>> Martin Wessendorf
>>
>> --
>> Martin Wessendorf, Ph.D.                   office: [phone]
>> Assoc Prof, Dept Neuroscience                 lab: [phone]
>> University of Minnesota             Preferred FAX: [phone]
>> 6-145 Jackson Hall, 321 Church St. SE    Dept Fax: [phone]
>> Minneapolis, MN  55455                    e-mail: [hidden email]

[Arvydas Matiukas]

*****
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Post images on http://www.imgur.com and include the link in your posting.
*****

Hello list,
 
please advise/share the latest options to store and backup
microscopy images. In our recently expanded core we
have 7 confocal/2p systems, and 3 more associated
systems producing time series imaging (all Windows based).
 10-20 TB of images (including second copy for analysis) are expected
to be generated per year.
 
What would be the next level instead of buying a lot
of cheap network storage devices (10TB , <$1k).
The most important considerations would be reliability,
ease of use, data transfer speed, tape backup option and price.
(e.g. <$120k for 350TB storage).
 
We will be using local 1Gbit/s and 100Mbit/s networks but
prefer manage the storage/backup ourselves (do not involve
IMT).
Thanks,
Arvydas

 
 
 
Arvydas Matiukas, Ph.D.
Director of Advanced Fluorescence Imaging Core
 SUNY Upstate Medical University
Neuroscience & Physiology Dept

[Craig Brideau]

*****
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Post images on http://www.imgur.com and include the link in your posting.
*****

We use a series of Pegasus RAIDs sold by Promise. They use twin Thunderbolt
ports so you can daisy-chain a bunch of them together (one port to the
host, other port to the next chassis in the chain). The biggest chassis has
8 bays, and you can put a 4TB drive in each bay for 32TB per chassis. They
tend to be a bit cheaper than 'real' enterprise solutions and seem fairly
reliable.  We've had ours running for a few years now (an earlier 4 bay
model) with no issues. We recently added an 8 bay system (Pegasus2) as well
and they seem to play well together. One hitch is to make sure your
thunderbolt drivers are up to date for the newer models. A current Mac Mini
Server can manage these systems fairly simply on a network without being
too expensive. Just make sure to buy a spare hard drive or two when you buy
them so you have a drive on hand that matches the original set. It will
make dealing with any drive problems much quicker.  I tend to keep a single
module per chassis in reserve just in case, although I have yet to use any
of these 'spares'.

http://www.promise.com/single_page_session/page.aspx?region=en-global&m=192&rsn=231

Craig Brideau



On Mon, Apr 7, 2014 at 11:52 AM, Arvydas Matiukas <[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 list,
>
> please advise/share the latest options to store and backup
> microscopy images. In our recently expanded core we
> have 7 confocal/2p systems, and 3 more associated
> systems producing time series imaging (all Windows based).
>  10-20 TB of images (including second copy for analysis) are expected
> to be generated per year.
>
> What would be the next level instead of buying a lot
> of cheap network storage devices (10TB , <$1k).
> The most important considerations would be reliability,
> ease of use, data transfer speed, tape backup option and price.
> (e.g. <$120k for 350TB storage).
>
> We will be using local 1Gbit/s and 100Mbit/s networks but
> prefer manage the storage/backup ourselves (do not involve
> IMT).
> Thanks,
> Arvydas
>
>
>
>
> Arvydas Matiukas, Ph.D.
> Director of Advanced Fluorescence Imaging Core
>  SUNY Upstate Medical University
> Neuroscience & Physiology Dept
>
>
>

[Smith, Benjamin E.]

*****
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.
*****

We use a pair of Synology DS 1812+.  The user interface on these servers is very friendly for us non-IT types, and there are plenty of security and automation features.  For example, our server is setup to only allow access via the University subnet, and only SFTP access.  Setting up unique encrypted accounts is a breeze, and I also have the server running a virus scan and SMART scan each night, as well as more thorough checks over the weekend.  Our backup server powers on only for the backup and a quick diagnostic self-check.  All in all, the system has been very nice and supports hybrid raid for memory expansion, as well as two external bays for a total of 18 drives.  We've also gone with 3TB drives rather than 4TB just to stay away from the "bleeding edge" of technology.

In my opinion, when you have to come in on Christmas day because the server failed to backup, you will greatly appreciate having something that's user friendly.

-Ben Smith
________________________________________
From: Confocal Microscopy List [[hidden email]] on behalf of Craig Brideau [[hidden email]]
Sent: Monday, April 07, 2014 1:19 PM
To: [hidden email]
Subject: Re: network storage server and backup

*****
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.
*****

We use a series of Pegasus RAIDs sold by Promise. They use twin Thunderbolt
ports so you can daisy-chain a bunch of them together (one port to the
host, other port to the next chassis in the chain). The biggest chassis has
8 bays, and you can put a 4TB drive in each bay for 32TB per chassis. They
tend to be a bit cheaper than 'real' enterprise solutions and seem fairly
reliable.  We've had ours running for a few years now (an earlier 4 bay
model) with no issues. We recently added an 8 bay system (Pegasus2) as well
and they seem to play well together. One hitch is to make sure your
thunderbolt drivers are up to date for the newer models. A current Mac Mini
Server can manage these systems fairly simply on a network without being
too expensive. Just make sure to buy a spare hard drive or two when you buy
them so you have a drive on hand that matches the original set. It will
make dealing with any drive problems much quicker.  I tend to keep a single
module per chassis in reserve just in case, although I have yet to use any
of these 'spares'.

http://www.promise.com/single_page_session/page.aspx?region=en-global&m=192&rsn=231

Craig Brideau



On Mon, Apr 7, 2014 at 11:52 AM, Arvydas Matiukas <[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 list,
>
> please advise/share the latest options to store and backup
> microscopy images. In our recently expanded core we
> have 7 confocal/2p systems, and 3 more associated
> systems producing time series imaging (all Windows based).
>  10-20 TB of images (including second copy for analysis) are expected
> to be generated per year.
>
> What would be the next level instead of buying a lot
> of cheap network storage devices (10TB , <$1k).
> The most important considerations would be reliability,
> ease of use, data transfer speed, tape backup option and price.
> (e.g. <$120k for 350TB storage).
>
> We will be using local 1Gbit/s and 100Mbit/s networks but
> prefer manage the storage/backup ourselves (do not involve
> IMT).
> Thanks,
> Arvydas
>
>
>
>
> Arvydas Matiukas, Ph.D.
> Director of Advanced Fluorescence Imaging Core
>  SUNY Upstate Medical University
> Neuroscience & Physiology Dept
>
>
>

[Smith, Benjamin E.]

*****
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.
*****

I think your analogy would better explain mode-locking rather than two photon excitation (as long as your waves all had the same phase velocity, and thus couldn't overtake one another).  The limitation of the wave analogy is that it negates the discrete (i.e. quantum) nature of light, such that each photon is a discrete packet.  This is better known as the wave-particle duality of light.

Also in continuum mechanics, such as ocean waves, you do not run into the issue of virtual states (that I know of) because phenomena do not need to behave quantumly.  It is when you start describing the excitation of a molecule that you run into the necessity of discussing quantum states, and thus the "virtual state" fudge factor.  As a Jablonski diagram shows so well, there are only certain allowed (i.e. observable) states.  As an intermediate state has an effective probability of zero, they are not allowed and are therefore virtual.  The fact that they are virtual doesn't mean that there isn't anything going on at all, but rather no excitation in the quantum sense.

The problem of reconciling continuum and quantum mechanics isn't limited to just multi-photon excitation either.

-Ben Smith  
________________________________________
From: Confocal Microscopy List [[hidden email]] on behalf of Feinstein, Timothy [[hidden email]]
Sent: Monday, April 07, 2014 10:25 AM
To: [hidden email]
Subject: Re: two-photon absorption

*****
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.
*****

Would it be a gross oversimplification to think of the 2p effect as
analogous to rogue waves on the sea?  Those occur when multiple waves
temporarily match vector and frequency and their amplitudes add together.
The sea wave analogy may help to explain why 2p is so nonlinear, as a
DeepSee or Cameleon always produces a range of wavelengths yet two waves
need to precisely match in space, vector and wavelength in order to go
rogue.

I know that quantum mechanics has a lot more going on than sea waves
sloshing around a Newtonian world and tipping the Poseidon over, but I
wonder how deep this discussion needs to go.

When teaching (elementary) FRET I always talk about what physicists
understand but practitioners do not necessarily need to memorize
themselves.  e.g., deriving the sixth power law or explaining what exactly
gets Œtransferred¹ if not a photon.  And if it is not a photon they why
does polarization still work?  What did space look like before the big
bang?  And so on down a hole chasing a rabbit with a pocket watch.  Note
that I am not trying to sidetrack the thread, I just want to suggest that
we specify how far down we want-slash-need to go.  Allowing of course that
folks have different needs.

Cheers,


TF

Timothy Feinstein, Ph.D. | Confocal Manager
333 Bostwick Ave., N.E., Grand Rapids, Michigan 49503
Phone: [phone] | Email: [hidden email]







On 4/7/14, 10:20 AM, "Smith, Benjamin E." <[hidden email]> wrote:

>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEN
>8ogAJZQ&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalmic
>roscopy
>Post images on
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDBZ
>98ApdNQ&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>posting.
>*****
>
>I find Paul Falstad's simulation helpful in visualizing energy state
>transitions.  The model shows how quantum state transitions can be
>thought of as continuous:
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEw
>s8g8KPA&u=http%3a%2f%2fwww%2efalstad%2ecom%2fqmatomrad%2f
>
>Since virtual states are unmeasurable, two photon excitation can be
>thought of as a coupling process between the two photons and the induced
>dipole:
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDBV
>4oQwLPA&u=http%3a%2f%2fresearchspace%2eauckland%2eac%2enz%2fbitstream%2f22
>92%2f433%2f2%2f02whole%2epdf
>
>The way I imagine it is as two separate yet simultaneous steps.  The
>first photon induces a dipole oscillation to a virtual state.
>Effectively simultaneously, a second photon also induces a further dipole
>oscillation kicking the dipole all the way up to an observable energy
>state.  The key is that both photons need to act on the molecule
>simultaneously, or the "virtual state" dipole disappears before the next
>photon can induce any further energy.
>
>An analogy would be trying to roll a boulder up onto a log.  Two people
>of equal strength set about the task of rolling over a boulder up onto a
>log.  Both people have enough strength to get the boulder to rock back
>and forth, but neither can get it up onto the log by themselves.  If one
>person tries to move the boulder, the boulder will rock back and forth,
>but the moment they stop, the boulder will come to a rest as though
>nothing had been done to it.  The rocking boulder can be thought of as a
>virtual state, where the boulder will drop back to its "ground state" the
>moment someone stops rocking it.
>
>However, two people decide to work together (this is like the coupling
>model).  They time their rocking together, and by doubling their effort,
>they are able to roll the boulder all the way over to the meta-stable
>state of being on top of the log.  The boulder will then reside atop the
>log for some time before dropping back down, emitting energy equal to
>both people's contribution, minus some energy due to friction an noise
>(just like two-photon emission).
>
>The reason why two photon excitation needs to be thought of as a coupling
>process, is let's think about a third scenario.  Person A starts to rock
>the boulder.  Then, person A lets go of the boulder and then person B
>immediately continues rocking the boulder.  Then end result of this
>effort would be a rocking boulder, however, since A and B aren't acting
>on the boulder at the same time, they won't ever be able to transition
>the boulder up onto the log.
>
>Finally, let's imagine a world where the boulder can only be measured
>based on it's height of the ground.  Rocking neither raises nor lowers
>the boulder, so it wouldn't be an observable state.  However, we know
>that the boulder would have had to have been rocked back and forth to get
>it up onto the log, so while we can't observe it, we know it must exist.
>
>Hope this helps,
>   Ben Smith
>
>Benjamin E. Smith, Ph.D.
>Samuel Roberts Noble Microscopy Laboratory
>Research Scientist II
>University of Oklahoma
>Norman, OK 73019
>E-mail: [hidden email]
>Voice   405-325-4391
>FAX  [phone]
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDBF
>59QAMNg&u=http%3a%2f%2fwww%2emicroscopy%2eou%2eedu%2f
>
>
>________________________________________
>From: Confocal Microscopy List [[hidden email]] on
>behalf of John Oreopoulos [[hidden email]]
>Sent: Monday, April 07, 2014 8:06 AM
>To: [hidden email]
>Subject: Re: two-photon absorption
>
>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEN
>8ogAJZQ&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalmic
>roscopy
>Post images on
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDBZ
>98ApdNQ&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>posting.
>*****
>
>If you're into quantum mechanical calculations, there is actually a
>fairly good derivation of the 2-photon process here at this link:
>
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEE
>roVoOPA&u=http%3a%2f%2fchemwiki%2eucdavis%2eedu%2fPhysical%5fChemistry%2fS
>pectroscopy%2fElectronic%5fSpectroscopy%2fTwo-photon%5fabsorption
>
>Cheers,
>
>
>John Oreopoulos
>Staff Scientist
>Spectral Applied Research Inc.
>A Division of Andor Technology
>Richmond Hill, Ontario
>Canada
>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDEx
>5pVtaZw&u=http%3a%2f%2fwww%2espectral%2eca
>
>On 2014-04-07, at 8:35 AM, Chen, De (NIH/NCI) [C] wrote:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>>
>>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDE
>>N8ogAJZQ&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalm
>>icroscopy
>> Post images on
>>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDB
>>Z98ApdNQ&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>>posting.
>> *****
>>
>> To my knowledge, one photon excitation is linear optical process
>>(dipole excitation, which is proportional to light intensity I), while
>>two photon excitation is nonlinear (quadrupole excitation, proportional
>>to I^2) ; In two photon absorption, an intermittent energy level close
>>to one photon resonance will enhance the two photon excitation depending
>>on the offset from the resonance energy level. Two photon excitation
>>requires high laser power to excite. Short pulsed laser can provide the
>>required high enough peak power to excite with two photon. Forbidden in
>>dipole excitation is allowed in quadrupole excitation.
>>
>> Reference:
>>   "The Principles of Nonlinear Optics" Y. R. Shen, 1984 | ISBN-10:
>>0471889989 | ISBN-13: 9780471889984
>>
>> ________________________________________
>> From: Marcus Knopp [[hidden email]]
>> Sent: Monday, April 07, 2014 5:53 AM
>> To: [hidden email]
>> Subject: Re: two-photon absorption
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>>
>>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDE
>>N8ogAJZQ&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalm
>>icroscopy
>> Post images on
>>http://scanmail.trustwave.com/?c=129&d=zbTC0zpLoupwLE6t2HWM55ZZjbebwN5SDB
>>Z98ApdNQ&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>>posting.
>> *****
>>
>> As far as I know, the effect, on the one hand, depends on the timing of
>>the subsequent photons to be absorbed. They have to reach a fluorophore
>>within a short time interval of sub-femtoseconds to a few femtoseconds,
>>i.e. quasi simultaneously. On the other hand, it depends on the symmetry
>>of a fluorophore, which, I think, determines the transition matrix
>>between energy levels. Then it all comes down to whether a transition is
>>allowed or not by the selection rules, which constrain transition for
>>example by the need to conserve an electron's angular momentum. What
>>exactly is going on, I don't know (does anybody?), but one
>>interpretation is indeed, that the first photon induces a transition
>>from the ground state to a virtual excited state at an intermediate
>>energy level (what's wrong with that? It's just a model). This is
>>thought to be close to a real state that can be occupied according to
>>the selection rules. The second photon carries the system from the
>>virtual state to the final state, that originally might have been
>>forbidden.
>>
>> Best,
>> Marcus
>>
>>
>> -----Original Message-----
>> From: Confocal Microscopy List
>>[mailto:[hidden email]] On Behalf Of Martin Wessendorf
>> Sent: Monday, April 07, 2014 4:24 AM
>> To: [hidden email]
>> Subject: two-photon absorption
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>>
>>http://scanmail.trustwave.com/?c=129&d=zrTC0wJ3Btfng3o6Ki8VL3Twis07aGkKBI
>>yvzD1R-A&u=http%3a%2f%2flists%2eumn%2eedu%2fcgi-bin%2fwa%3fA0%3dconfocalm
>>icroscopy
>> Post images on
>>http://scanmail.trustwave.com/?c=129&d=zrTC0wJ3Btfng3o6Ki8VL3Twis07aGkKBN
>>munjcFqA&u=http%3a%2f%2fwww%2eimgur%2ecom and include the link in your
>>posting.
>> *****
>>
>> Dear List--
>>
>> Is there a physicist out there who can offer an intuitive explanation
>>of how 2-photon absorption occurs?  I expect we all know that it isn't
>>that there isn't any half-excited state that allows one photon to boost
>>an electron half-way to the excited state, and the next photon to finish
>>the job.  My sense is that it has to do with time-energy uncertainty (a
>>la Heisenberg) but my quantum mechanics is elementary-school level.
>>
>> Thanks!
>>
>> Martin Wessendorf
>>
>> --
>> Martin Wessendorf, Ph.D.                   office: [phone]
>> Assoc Prof, Dept Neuroscience                 lab: [phone]
>> University of Minnesota             Preferred FAX: [phone]
>> 6-145 Jackson Hall, 321 Church St. SE    Dept Fax: [phone]
>> Minneapolis, MN  55455                    e-mail: [hidden email]

[Dave Mason]

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Post images on http://www.imgur.com and include the link in your posting.
*****

Hello all,

I've dealt with this problem at a few institutions. At Liverpool we've
recently installed two 60TB servers (36 bay 4U rack mount, with RAID6). Only
one is accessed by users and the other serves as a mirror to those data,
with incremental backups happening in the evenings/weekends (we use robocopy
and rsync for backups depending on the platform). The server will also host
our OMERO server, which we're hoping will take care of our file
management/record keeping needs.

We were looking at a NAS solution but the selection is poor when you require
24+ disks and multiple 10Gb network connections.

By my estimates you can get about 60TB (mirrored - so 120TB but with two
copies of your data) for £20k. If you're looking for 350TB I guess that's
around £120K (these are obviously UK prices). If you don't want to involve
your IT department, it could get more expensive as you should also be
thinking about air cooling, power smoothing, battery backups, physical
security &c.

Dave Mason

---------------------------------------------------
Centre for Cell Imaging
University of Liverpool
Institute of Integrative Biology, Biosciences Building
Crown Street, Liverpool L69 7ZB, UK
---------------------------------------------------

[jerie]

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*****

A former colleague of mine has recently pointed me to a server solution for
bio imaging platforms that might be of interest also for those non IT
experts. Check http://www.acquifer.de/hive-platform-features/
No commercial interest.
Cheers, Jens
Am 08.04.2014 05:33 schrieb "Dave Mason" <[hidden email]>:

> *****
> 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 all,
>
> I've dealt with this problem at a few institutions. At Liverpool we've
> recently installed two 60TB servers (36 bay 4U rack mount, with RAID6).
> Only
> one is accessed by users and the other serves as a mirror to those data,
> with incremental backups happening in the evenings/weekends (we use
> robocopy
> and rsync for backups depending on the platform). The server will also host
> our OMERO server, which we're hoping will take care of our file
> management/record keeping needs.
>
> We were looking at a NAS solution but the selection is poor when you
> require
> 24+ disks and multiple 10Gb network connections.
>
> By my estimates you can get about 60TB (mirrored - so 120TB but with two
> copies of your data) for £20k. If you're looking for 350TB I guess that's
> around £120K (these are obviously UK prices). If you don't want to involve
> your IT department, it could get more expensive as you should also be
> thinking about air cooling, power smoothing, battery backups, physical
> security &c.
>
> Dave Mason
>
> ---------------------------------------------------
> Centre for Cell Imaging
> University of Liverpool
> Institute of Integrative Biology, Biosciences Building
> Crown Street, Liverpool L69 7ZB, UK
> ---------------------------------------------------
>

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*****

Hi,


Has anyone tried to use Amazon Glacier (http://aws.amazon.com/glacier/) for storage?


Sincerely


Cédric Espenel , Associate Research Scientist, Ph.D.


Manager of the Confocal and Specialized Microscopy Facility



Phone: [phone]
----- Original Message -----

From: "Arvydas Matiukas" <[hidden email]>
To: [hidden email]
Sent: Monday, April 7, 2014 1:52:19 PM
Subject: Re: network storage server and backup

*****
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*****

Hello list,

please advise/share the latest options to store and backup
microscopy images. In our recently expanded core we
have 7 confocal/2p systems, and 3 more associated
systems producing time series imaging (all Windows based).
10-20 TB of images (including second copy for analysis) are expected
to be generated per year.

What would be the next level instead of buying a lot
of cheap network storage devices (10TB , <$1k).
The most important considerations would be reliability,
ease of use, data transfer speed, tape backup option and price.
(e.g. <$120k for 350TB storage).

We will be using local 1Gbit/s and 100Mbit/s networks but
prefer manage the storage/backup ourselves (do not involve
IMT).
Thanks,
Arvydas




Arvydas Matiukas, Ph.D.
Director of Advanced Fluorescence Imaging Core
SUNY Upstate Medical University
Neuroscience & Physiology Dept