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Hi Dale, the shorter the pulse you use, the less collateral damage there
will be. The shorter the pulse is in time, the broader its spectrum must
be. The broader its spectrum is, the harder it is to focus accurately due
to NIR chromatic aberration. The Coherent Vitara has adjustable bandwidth,
so you might be able to use that to play with the pulse parameters until
you get optimal ablation. I believe its center wavelength is fixed around
800nm approximately, but then you can alter the bandwidth around this
point. You would also need a pulse compression setup (Coherent of course
sells these too) to keep everything from getting excessively dispersed.
Another thing to consider is that high pulse energy can cause photochemical
damage, especially in the presence of oxygen, so this might be an issue for
you as well.

You are opening a can of worms with this one, but you could get some
interesting results!

Craig Brideau

On Tue, Jun 30, 2015 at 10:40 AM, Dale Moulding <[log in to unmask]>
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.
> *****
>
> Dear list,
>
> I'd be very grateful for some advice regarding a multiphoton laser for
> point ablations. We
> want to ablate individual centrosomes in zebrafish embryos without
> damaging the rest of
> the cell. We plan to do this with water dipping objectives (NA ~1.0) on a
> confocal system
> with an 80 MHz multiphoton laser.
> What factors should we consider in the choice of laser?
> Is there a benefit for extremely short pulse width (say ~75 fs vs ~140 fs)?
> What range of average power or peak power should we be aiming for?
> Are there any published reports or guidance for optimising ablations?
>
> Many thanks
>
> Dale
>
> Imaging Facility Manager
> UCL Institute of Child Health.
>