Re: pre-chirping (what diagnostics to use)

Posted by Mark Cannell on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Re-pre-chirping-what-diagnostics-to-use-tp590162p590171.html

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Hi Shalin

The spectrum analyser is a must have instrument that will fill most of
your needs. You will be able to to tune to  the desired wavelength and
bandwidth quite easily.

Cheers Mark

Shalin Mehta wrote:

> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal Dear Jerry and
> others,
>
>  What diagnostics do you use for tuning of two photon laser or OPO? Is
> laser spectrum analyzer enough?
>
> We have a shared two photon (MIRA 900F Femtosecond configuration) and
> OPO from Coherent. One of the main user is very afraid of tuning it -
> so he always has a service engineer tune it to 830nm and longest
> possible pulse (since he does spectroscopy). There are two more of us
> who will benefit by tuning it for two-photon and SHG (different
> wavelengths and shortest possible pulse).
> How is the 'reproducibility' of laser beam profile when working with
> these lasers? One of the main concern that other user has is that - if
> you cannot come back to exactly 830 nm after tuning to say 740 nm, the
> custom optical setup will go out of alignment.
>
> Thanks
> Regards
> Shalin
>
>
>
> On 8/30/07, *Mark Cannell* <[hidden email]
> <mailto:[hidden email]>> wrote:
>
>     Search the CONFOCAL archive at
>     http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>     Hi Gerry
>
>     The typical path using 2 prisms is via a small mirror into the first
>     prism (we set this at minimum at minimum deviation but this can be
>     changed to alter chirp). Then to the second prism (at minimum devation
>     to produce a collimated horizontally spread spectrum), and then two
>     mirrors to reflect the light back and displace the beam vertically
>     which
>     then passes back through the second and first prisms respectively.
>     After
>     the beam has left the first prism, note the beam has been displaced
>     vertically is and thereby separated from the input beam.
>
>     BUT are you sure you need to do this? If the input pulse is ~120
>     fs the
>     pulse broadening is quite minor. We used a pair of gold mirrors to to
>     return and displace the beam but if you have 1" fs mirrors they would
>     work as well.
>
>     For typical prism spacing see:
>
>     Soeller, C. & Cannell, M.B. (1996) Construction of a two-photon
>     microscope and optimisation of  illumination pulse width. _Pflugers
>     Archiv_ 432: 555-561.
>
>     Cheers Mark
>
>     Jerry Sedgewick wrote:
>     > Search the CONFOCAL archive at
>     > http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>     >
>     > I am interested in setting up pre-chirping in the laser path
>     going to
>     > a custom built multiphoton. I have been searching in vain for exact
>     > information on the components. I bought the prisms, but I am
>     uncertain
>     > about the first mirror that directs the laser to the prisms (and
>     then
>     > allows the returning, reflected laser to pass through), and the
>     second
>     > mirror. My guess is that the first mirror must be a linear
>     polarizer,
>     > or a polarizer that separates the s and p polarization. The second
>     > mirror must be a grating of some sort that re-polarizes the laser so
>     > that it passes through the first mirror.
>     >
>     > Rather than guessing, it would make my day if I could get
>     specifics on
>     > the mirrors.
>     >
>     > Thanks!
>     >
>     > Jerry Sedgewick
>
>
>
>
> --
> My co-ordinates:
> Shalin Mehta, Graduate student
> Graduate Programme in Bioengineering, NUS, Singapore
> Email: shalin {dot} mehta {at} gmail {dot} com
> Blog: electricsbm.blogspot.com <http://electricsbm.blogspot.com>
> Mobile: +65 90694182