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Dear Loralei:

I would add that there is nothing magical about the laser light, other
than that due to its "brightness" (watts per cm^2 per steradian per unit
wavelength), it is generally easier to focus more watts through a
pinhole.  But as long as you can get enough light through the pinhole,
even if it comes from a broadband, less-coherent arc-lamp source, you
can still do excellent confocal imaging.  In the case of the Olympus
system, they don't actually use a single pinhole, as in conventional
laser-scanning confocal systems, but rather a disk with a series of
crossed linear apertures, such that when the disk spins the pattern of
light that gets through the disk as a function of time appears like an
array of moving apertures (it is a variation of the so-called "Nipkow
disk" which contains an array of actual pinholes arranged in a spiral
pattern).  These sorts of spinning disk systems make more efficient use
of the light than single-pinhole, laser-scanning confocal systems, and
therefore are able to function quite well even with less-bright,
non-laser sources.  Of course if you can get away without using lasers,
you gain the flexibility of having all wavelengths available to you,
plus compactness, less heat, etc., which is why it makes sense to use a
lamp if you can.

Hope that helps a little more.


Sincerely, Turan

Dr. Turan Erdogan, CTO

Semrock, Inc.

3625 Buffalo Road

Rochester, NY 14624

tel:  (585) 594-7001

fax:  (585) 594-7095

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www.semrock.com

 

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-----Original Message-----
From: Peng Xi [mailto:[log in to unmask]] 
Sent: Tuesday, June 05, 2007 11:11 AM
To: [log in to unmask]
Subject: Re: Confocal without lasers


Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal

Hi,
    The core for confocal is: the excitation source focal spot and the 
detection focal spot matches each other via the target focal spot. Then,

if you put sample onto the target spot, the detector detects the energy 
only from this spot and rejects adjacent.
    So the key for excitation is to make a spot. A laser, is an ideal 
source to do that. On the other hand, any pinhole (or a pinhole array) 
can be a point source. Of course, you have to match the excitation 
pinhole(s) to the detection pinhole(s) via the target pinhole images.
    In the case of Olympus Spinning disk, it has an epi-illumination so 
the excitation and detection uses the same pinholes and they line up 
together automatically.
    Wish this helps!
Peng

-- 
Sincerely,
Peng Xi
Dantus Research Group
Department of Chemistry
Michigan State University
East Lansing, MI 48824
Tel: (517) 355-9715 x319
Email: [log in to unmask]
http://www.msu.edu/~xipeng/


Loralei Dewe wrote:
> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
> Hi All,
>  
> I may be putting my foot in my mouth but I do not understand how a
> system can be a true confocal without lasers. We just purchased an 
> Olympus Spinning Disk system which uses a Mercury lamp and filters. I 
> thought it was by virtue of the lasers being able to penetrate the 
> tissue and focus on all the layers making a 3-D image that made a 
> Confocal but the Olympus rep swears theirs IS a true confocal. Can 
> someone explain this to me for my education?
>  
> Thanks
>  
> Loralei Dewe
>
>
>
> ----------------------------------------------------------------------
> --
> See what's free at AOL.com 
> <http://www.aol.com?ncid=AOLAOF00020000000503>.