>Hello All!
> Your responses about digital cameras were so informative, I
>would like to
>try again. Does anyone have any suggestions/recommendations for a digital
>video-rate camera? We're looking to hook it up to an F-mount or C-mount on
>a Zeiss Axiovert, Olympus BMAX, and Olympus stereoscope. We're monitoring
>blood flow in mouse vessels. Any comments would be appreciated.
> Thanks in advance.
> Kathy Spencer
>
>
>
>
>Kathy Spencer
>The Scripps Research Institute
>10550 N. Torrey Pines Road
>IMM 24
>La Jolla, CA 92037
>(858) 784-9372
>[log in to unmask]
Hi Kathy,
I sent this out earlier in response to another question but it may be
relevant to your question too.
Jim P.
Anyone interested in a new CCD for microscopy should look at the new
CAM 65 from Marconi (used to be EEV, call Ian Moody
<[log in to unmask]> for more details) which was shown at the SPIE
meeting three weeks ago.
MORE INFO AT
http://www.marconitech.com/ccds/lllccd/technology.html
It is a TV-rate chip with a (real!) difference. While working at
about 50 electrons of noise/pixel may sound useless (though not bad
for Video rate), the clever idea is that there is a GAIN section in
the horizontal register, just before the readout node, that can
operate as a series of very low gain avalanche diodes. When the
signal is low, this section multiplies small charge packets by about
200x, lifting even single electrons well above the noise floor.
So you have a normal CCD, that reads out so fast that there is no
point in cooling it, making focusing etc. quick and easy, that has
the QE of a CCD, the full resolution of a CCD because the charge
packet from one pixel is always handled as a discrete entity (unlike
intensified CCDs) and which can be made as sensitive as you need. Of
course, if you readout fast, there may not be enough time to collect
much signal but this isn't the camera's fault. On the other hand this
system breaks the old rule that you must get more readout noise if
you readout faster.
There IS one snag.
The charge amplification is not quite noise free. Because the exact
amount that the packet will be amplified depends on probability, the
camera as a whole operates as if it is noise free but has one half
the QE listed for the sensor alone. This reduction in effective QE
occurs only when you use the amplifier. If you turn it off or work in
the photon counting mode, the QE is as advertised.
When the sensors are available in back-illuminated models, they will
have QE of about 85% or 42% when used in the charge amplifier mode:
still very good.
The models now being introduced have pixels that the pixels aren't
square ( 20 x 30 microns) and cost between $10 -20k (analog vs full
digital). Later models will be back illuminated and 512x512.
I don't have much more info than this but I was very impressed at SPIE.
This seems like it should be a really good idea.
Sadly, I still have no connection, financial, or otherwise with Marconi.
Cheers,
Jim P.
--
****************************************
Prof. James B. Pawley, Ph. 608-263-3147
Room 223, Zoology Research Building, FAX 608-265-5315
1117 Johnson Ave., Madison, WI, 53706 [log in to unmask]
"A scientist is not one who can answer questions
but one who can question answers."
Theodore Schick Jr., Skeptical Enquirer, 21-2:39
|
