Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal

Tuning is fairly easy with the MIRA, and reproducibility should be no 
problem. If you have a spectrometer and an autocorrelator, you can 
guarantee virtually the same pulse that you had before. For the 
pulsewidth at a given wavelength, all that should matter is the amount of 
prism glass you put 
in the beam (generally less for longer pulses) and the slit width 
(assuming that the prism angles are set correct and you do not want to 
play with those).
Sudipta
  On Thu, 30 Aug 2007, 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 <[log in to unmask]> 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
>>
>
>
>
>

-- 
Sudipta Maiti
Dept. of Chemical Sciences
Tata Institute of Fundamental Research
Homi Bhabha Road, Colaba, Mumbai 400005, India
91-22-2278-2716
www.tifr.res.in/~biophotonics