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Hi,

Thanks for the replies!


Actually, I'm quite surprised that this fast PMT preamplifier seems to be rather uncommon. When somebody uses a 8 kHz resonant scanning confocal microscope at the lowest zoom, he might want to have not 512x512 pixels, but 2048x2048 pixels or even 4096x4096 pixels. That's not always useful for time-lapse imaging (as Zdenek pointed out), but very useful for taking a single picture or a z-stack with a lot of averaging. And to resolve 4096 pixels at a 8 kHz-scanned line (63 us for one line), you have to sample at ca 80 MHz.

Right now, I'm sampling at 80 MHz, and only when I do not need the full 4096 pixels, I bin it down in the software. But even for functional imaging, sometimes a very big picture - like 2048x512 - can be very useful.

Today, by coincidence, I called Becker&Hickl, and most likely I will test one of their ACA amplifiers side to side to the preamp that I'm using right now. (I was planning to take the 37dB preamp.) Becker&Hickl are specialized on photon counting technology, so this will be rather an abuse of their preamp. I will report the results in some weeks, if somebody is interested.

@Zdenek: A SNR of 3.5 or a little bit more might be enough for some applications ... I was planning to measure the photon count per pixel (using this method : 
http://labrigger.com/blog/2010/07/30/measuring-the-gain-of-your-imaging-system/ ), but I always was busy with other things, so I cannot give you numbers for my imaging system.

@Craig: Are you possibly talking about this amplifier: 
http://www.hamamatsu.com/jp/en/C9663/index.html ? Are there any drawbacks, and can you compare it to other amplifiers?

Michael wrote >> You can have a lot of cabling and amplification in your system so long as you are careful to manage GVD.

This is a little bit off-topic, but until now, I was simply sticking BNC cables with a 50 kOhm sign together, hoping that this would do it... however, I have the feeling that I get some lowpass-filtering / GVD of my detection signal. Do you have any tips for how to check and minimize the system's GVD?


Best,
Peter