On Aug 26,  4:33pm, [log in to unmask] wrote:
> Subject: Re: Yokogawa CSU10 (Nipkow disk confocal)
> We at Meridian have been extoling the virtues of ocular viewing confocal for
> many years.  The improvements in productivity are phenomenal.  Both the
> Yokogawa CSU10 and our own InSight Plus illuminate multiple locations within
> the sample simultaneously to get the better signal to bleach performance, and
> CCD output at up to video rates.  They use a scatter of points, while we line
> them all up as a vertical laser cursor, which is swept across the specimen
> 120 times per second.  If you can't wait for their muticolor option, we have
> it already on our InSights, which cost about the same and give better axial
> resolution.
>
I think that this is not completely accurate. The Nipkow disk system uses a
scatter of points which are supposed to be sufficiently separated that each
point acts independently, so the resolution and other optical characteristics
are those of a point scanning system. On the other hand, a line scanning system
is not simply a collection of independent pinholes in a line -- the pinholes
are correlated, and it will have certain advantages and also disadavantages.
There was a very good paper comparing the resolution and S/N of different
scanning/descanning methods (point/point, point/line, line/line, etc) which
described these tradeoffs, but I cannot find the reference at present. The gist
of the paper was that for a given S/N ratio, use use less excitation light with
a line scanning system, but you have a much lower signal to background ratio in
a specimen with uniform background fluorescence.

The main drawback with Nipkow disk systems is the poor light budget, which in
the past tended to restrict their use to reflection microscopy (eg, in
semiconducter inspection and such). There are other issues, such as how you
modify the pinhole size on a Nipkow disk.

There is a system I read about in Nature (31 Oct 1996, p 804) which uses a disk
with apertures which form Golay sequences (ie, each line is a vector which is
orthogonal to all the others). The result is a system that uses 1/2 of the
light. Half of that forms a conventional image, and the other half can be
processed to provide a confocal image. Has anyone seen this instrument, and is
it being developed for commercial use?

--aryeh

--
Aryeh Weiss                          | email: [log in to unmask]
Department of Electronics            | URL:   http://optics.jct.ac.il/~aryeh
Jerusalem College of Technology      | phone: 972-2-6751146
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