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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 
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-----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

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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
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206-280-5597
Andor Technology
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Web: www.andor.com 
Main US Office: 860-290-9211