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Hugo Ostermann |
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Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
Dear Listers,
I have tested this Scott's approach
"2X magnifier with a 1k x 1k backthinned EMCCD that has 13 um pixels to give
you an effective pixel size of 6.5um."
with a Cascade II 512x512 16µm pixel on a DeltaVision Microscope.
I found that I got 4 times less light to each pixel so the net effect was
unvisible. The Standard Roper HQ Camera gave much nicer and less noisy
images.
What do the specialists say to this "post objective lens magnification"
Best regards
Hugo Ostermann
[log in to unmask]
-----Ursprüngliche Nachricht-----
Von: Confocal Microscopy List [mailto:[log in to unmask]] Im
Auftrag von Scott Phillips
Gesendet: Mittwoch, 11. Juli 2007 18:12
An: [log in to unmask]
Betreff: Re: AW: Hamamatsu EMCCD
Search the CONFOCAL archive at
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NOTE: Commercial Interest
Dear Kathy,
I agree with what Arne has said, especially the part about practical
testing of different cameras on your system and seeing how they work on
your samples. All the cameras companies are happy to loan you a camera to
make these tests.
For dendritic spines, I understand the desire for small pixel sizes. The
Orca ER has 6.45um pixels, which is great for getting the detail of these
small objects. Andor offers EMCCDs in a variety of flavors with pixel
sizes at 8um, 10um, 13um, 16 um and 24um. In particular we offer a system
that combines a 2X magnifier with a 1k x 1k backthinned EMCCD that has 13
um pixels to give you an effective pixel size of 6.5um. In this way you
have the advantages of the EMCCD technology combined with resolution.
The beauty of the EMCCD is its ability to boost the signal before it gets
to the readout amplifier. In this way one is no longer limited by readout
noise and is able to get a good signal with fewer photons. These cameras
do have a larger read-noise than some of the conventional CCD cameras, but
this can be off-set by using a little bit of gain to effectively negate
that read noise. Too often users crank the EM gain way up and complain of
increased noise. It is true that there is an inherent noise to these
cameras (CIC, or Clock-induced Charge) but it is related to the strength
of the gain. Using an EMCCD at gains less than 300x makes them a very
effective imaging tool. The ability to image with fewer photons means
that you can image your sample longer with less damage.
One last note of the use of the Optivar in conjuction with the Yokogawa
spining disk. Since the excitation light is also passing through the
optovar, you are expanding the incoming light beyond the back aperture of
the objective and throwing away some of your excitation light. I was
speaking with representatives from Yokogawa at Jim Pawley's course a
couple of weeks ago and they concurred that if you need more magnification
it is best to change objectives. The alternative is to place a magnifier
in front of the camera so as not to affect the excitation path, as offered
by Andor.
Cheers,
Scott Phillips
Imaging Applications Specialist
[log in to unmask]
206-280-5597
Andor Technology
discover new ways of seeing
Web: www.andor.com
Main US Office: 860-290-9211
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