http://confocal-microscopy-list.275.s1.nabble.com/Re-Preamplifier-for-fast-point-scanning-tp7583751p7583757.html
(like all HF amps, but I thought it worth mentioning). Keep it short for
less HF roll-off. I have these on a Thorlabs Bergamo and they have the amps
piggy-backed right on top of the PMTs with a very short cable. It seems to
in the room. We spent a lot of time pointing these away from the microscope
> *****
> 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 Peter,
>
> Those artifacts are indeed caused by the AC coupling. A bright signal
> causes a shift of the zero level that persists for some time
> afterwards. You can however remove them with digital filtering by
> treating the data you record as an AC signal modulated at 80 MHz with
> the intensity of your image encoded in the envelop.
>
> For what its worth, Thorlabs has begun selling their TIA-60 product
> (previously you could get it only with a complete system), which is
> specifically designed for fast MPM imaging with the H7422:
>
>
http://www.thorlabs.de/newgrouppage9.cfm?objectgroup_id=8862>
> We have several of these, and while they do roll off a little before
> 80MHz, their performance is excellent and they are reasonably priced.
> They are also DC coupled and, provided you use the included cabling,
> are quite stable with an H7422. I would strongly recommend this part
> for an 80 MHz system. Its not worth paying more unless you have a
> very high rep rate system.
>
> Mike
>
> On Wed, May 13, 2015 at 11:29 AM, Peter Rupprecht
> <
[hidden email]> 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,
> >
> > this is a follow-up on my earlier post some months ago:
> >
>
http://confocal-microscopy-list.588098.n2.nabble.com/Preamplifier-for-fast-point-scanning-td7583344.html> >
> > Shortly after this post, I tested the ACA-4-40 preamplifier from
> Becker&Hickl and compared it directly to the Femto DHCPA-100. Amplification
> and noise seemed to be in the same order of magnitude for both products for
> my setup. Although performance might be also dependent on bandwidth of PMT
> and other details that I cannot test properly. I realized that comparing
> the two products objectively would involve more than just one experimental
> setup.
> > The one annoying thing that was also mentioned before by Michael, seems
> to be the AC-coupling of the preamp. At least this is how I interpret the
> strange artifacts that I see in the wake of very bright objects. This is
> very clearly visible when scanning bidirectionally, because then this
> artifact clearly shows the scanning direction.
> > Here is an excerpt of an image which shows how this may look like for
> calcium imaging (this is averaged over a couple of frames); please note the
> picture titles:
> >
>
https://www.dropbox.com/sh/bwxxjrw44yxxb0p/AAAM9yWeMMc37NT_VORDEiaBa?dl=0> >
> > Based on my limited experience, I would conclude that the B&H ACA is
> maybe better for photon counting or flourescence lifetime imaging (due to
> higher bandwidth), but not the appropriate solution for my calcium imaging
> experiments.
> >
> > Peter
>