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Hi John,

As mentioned by others, you would need to a second, synchronized 
scanner to descan the transmission path.

Fortunately, the transmission path is a great place to put 
non-descanned detectors for multiphoton microscopy. The "NDD-T" 
detectors can be for the laser wavelength (good idea to attenuate the 
signal when using a 3.3 W average power Ti:Sapphire laser line!), 
second harmonic generation, and/or fluorescence. Steve Vogel (NIH) 
put his TCSPC FLIM fluorescence detectors after a dual dry/oil high 
NA condenser for his Zeiss LSM510 multiphoton microscope. Steve said 
it was much easier to add the detectors to his system that way. With 
respect to SHG, Watt Webb's group has published comparisons of epi- 
vs transmission-SHG.



With respect to transmission microscopy in general, what appears 
opaque to the eye may be almost transparent in the near infrared. For 
example, an ~6 mm thick mouse brain transmits enough light at >700 nm 
to see red polymer filled blood vessels using a standard 
tungsten-halogen lamp and good digital CCD camera. Same specimen is 
completely opaque in the visible or with white light source and no 
wavelength selection. This was exploited years ago by Dodt and 
Zieglgansberger in near infrared video enhanced differential 
interference contrast optical sectioning microscopy of brain slices. 
The principle is easily demonstrated with a red (but not green) laser 
pointer and finger.




At 10:03 AM 11/6/2007, you wrote:
>Search the CONFOCAL archive at 
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>Hello folks,
>
>Here is one of those seemingly straightforward to answer questions 
>that has me really stumped.  You should hear all of the BS around 
>here when I bring this up with the other confocal 'experts'.  Why 
>isn't there a pinhole in the transmission-image forming pathway?  A 
>confocal transmission image would be nice but I always tell people 
>it's not possible.  Is it not possible or just not done?
>
>Thanks for your help.  John.
>--
>*********************************
>C. John Runions, Ph.D.
>School of Life Sciences
>Oxford Brookes University
>Oxford, UK
>OX3 0BP
>
>email:  <mailto:[log in to unmask]>[log in to unmask]
>phone: +44 (0) 1865 483 964
>web: 
><http://www.brookes.ac.uk/lifesci/runions/HTMLpages/index.html%21>http://www.brookes.ac.uk/lifesci/runions/HTMLpages/index.html!
>
>
>New - Oxford Brookes Master's in 
><http://www.brookes.ac.uk/studying/courses/postgraduate/2007/bmt>Bioimaging 
>with Molecular Technology






George McNamara, Ph.D.
University of Miami, Miller School of Medicine
Image Core
Miami, FL 33010
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305-243-8436 office
http://home.earthlink.net/~pubspectra/
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Analytical Imaging Core Facility)