Re: Zeiss or Olympus

Posted by Andreas Bruckbauer on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Zeiss-or-Olympus-tp4702418p4707747.html

Just to clarify, the 780 has a GaAsP (Gallium Arsenite Phosphate) detector, not GaAs, the difference in quantum efficiency can be seen e.g. in the Webb multiphoton review (Nature Biotechnology 2003, 21, 1369). The drawback is that GaAsP QE dropps dramatically for wavelength > 700 nm, but they put a normal PMTs as the two additional channels on the 780, to cover the extended range. By the way GaAsP detectors are PMTs as well, it is just a different material of the photocathode, afterwards the photoelectrons are multiplied in the same way. GaAsP detectors reach 40% quantum efficiency which is about twice as sensitive as a normal PMT. APDs have 60-70% and a back-thinned CCD about 90%., so still a lot of signal is thrown away, not to mention the losses on the way to the detector.

Andreas

-----Original Message-----
From: Axel Kurt Preuss <[hidden email]>
To: [hidden email]
Sent: Wed, 10 Mar 2010 3:08
Subject: Re: Zeiss or Olympus

Just to mention, should one be stuck with PMTs instead GaAs,   one could play with the applied bias voltage to modify   dark noise   (to  

  balance the  gain   versus noise.  )

Nice thing with Olympus Kalman filtering is   that its use would allow   increase the bias voltage of PMT   

 

 

 

 

Thanks

 

Axel   Central Imaging  (IMCB)  6-19B,  cell  +65 9271.5622

 

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From: Confocal Microscopy List [[hidden email]] On Behalf Of RICHARD BURRY
Sent: Wednesday, March 10, 2010 8:17 AM
To: [hidden email]
Subject: Re: Zeiss or Olympus

 

Mark
 
I was thinking about the use of GaAs ( gallium asrenide) detectors for multiphoton by Zeiss for the NLO.  This are not a PMT and have very different properties. 
 
Dick Burry

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