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

Dear Mario,
My experience is that for measuring pH in small neuronal compartments (i.e.
dendrites) confocal microscopy works much better than wide-field imaging
(even with the pin-hole wide open). A scanning confocal deals well with
overlapping structures, bright regions near dim ones, rejecting the massive
amount of fluorescence from the patch-pipette (which is full of dye) and
allows complex morphology to be reconstructed. So, I am convinced that a
confocal is the correct piece of equipment.
It seems to me that the Zeiss Pascal could do excitation ratio imaging
faster than normally possible, by using external shuttering rather than the
MOTF.
Since the modifications are essentially external to the confocal I cannot
see why it should cause any warranty/servicing problems. Furthermore, the
proposed voice coil shutter is very low cost and simple to implement (at
least that is what I imagine).
Greetings,
Christof

On Mon, 24 Jan 2005 14:59:51 -0800, Mario <[log in to unmask]> wrote:

>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>Christof,
>
>It would seem that you want to make a system that has the responsive
>of a AOTF system without the cost. On the other hand you make it
>sound as though AOTF speed is overkill for what you need. So,
>Christof, what are your requirements? If you can work in the
>millisecond time scale then you might not even need a CLSM confocal
>and can use mechanical shutters and filters with a WF scope and good
>detectors or CCDs.
>
>Commonly for confocals, the typical residence times of the lasers are
>often from 4-12 usec. per pixel. Usually with repeat scans to average
>out noise. So say maybe 10 to 30 usec./pixel. From the paper that
>Guido kindly referenced, the voice coil system can provide speeds
>comparable to the above system, but if that is what you want, it
>makes more sense to buy one that you know will work, can usually be
>certain of getting serviced, and requires no relatively exotic
>engineering on your part.
>
>If you are intent on building something yourself you might contact
>the people at Newport, Melle-Griot, or
>http://www.eopc.com/shutters.html. The latter seems to have a good
>assortment of shutters, controllers, and AOTFs if you want your own.
>
>When you have come to a conclusion, please let me know what you've
>decided. I am interested as perhaps others are on the list,
>
>Ciao,
>Mario