Re: Preamplifier for fast point-scanning

Posted by Peter Rupprecht on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Re-Preamplifier-for-fast-point-scanning-tp7583751.html

*****
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