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Hi Pascal, rather than an AOM, I'd suggest a pulse picker for the laser.
It's a fairly common option for these types of systems. They let you adjust
the repetition rate of the laser to control the number of pulses hitting
the target within a given interval. For ablation this tends to be more
important than average power control. Higher end pulse pickers also act as
a shutter, allowing you to let through a short burst of pulses at a time
and rate, which is optimal for point ablation.

Craig Brideau


On Tue, Jun 30, 2015 at 11:29 AM, Pascal Weber <[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.
> *****
>
> Hi,
>
> In fact you also have consider optical elements that are in the path.
> But if you want a quick removal switch your choice will be on an AOM. Turn
> fast
> to generate short pulses. The AOM is a crystal and he will disperse most
> passing 100fs over 500fs. You can use a prechirp for dispersion.
> The 20X, NA = 1.0 is a good choice. If you want to control the peak power
> you
> must know the average power under the lens. (Thorlabs sells power-meter) to
> measure the width of implusion you must use an autocorrelator. He alone
> will
> allow you to edit the values of your system: APE berlin.
> http://www.ape-berlin.de/sites/default/files/Carpe_0.pdf
> http://www.ape-berlin.de
>
> Also you must be sure to fill the rear element of the lens and check the
> consistency of your field. For that I use a flat mirror and a visible
> laser to
> ensure the setting.
>
> With a lens 10 NA = 0.5 , I obtain with the zoom mini 5% of in-homogeneity.
> (diagonals of the square)
> for your bleaching it is always best to use the laser where it is most
> powerful.
> Generally 800nm
>