Natural Science Forum / Physics / Optics / July 2008

I am doing SHG experiment using a fs-laser (140fs pulse width) on a
probe on silicium substrate.
As a preliminary test, I measured a reflection SHG spectrum from a bare
silicium wafer, expecting to get no signal. However I get two peaks

I have some 6580 drivers here which are missing the RC4200N multiplier
chip.  I seem to recall that the driver will work without the chip, but
I can't find any reference to that.  Does anyone know if the driver will
work ok for laser show use without the chip?  If so, what's it in ...

I need to build eye safe IR illuminator for CCD camera, few month ago
I had a look at IR illuminator made in Germany (860nm) and it was a
great little illuminator, focusing through all range very good (unlike
LED ir) and had plenty of power output, much better then LED. It also

Does anyone have an 8 Channel NEOS / PCAOM they're wanting to sell?
I'd prefer a 10 watt crystal, but a 5 watt would do (or even a 15 watt for
that matter)
Must be in good condition, preferably complete with Bragg mount.

Hi all, I have a question I have not been able to resolve through an
exhaustive search and  thought I would give it a try here.
 I am working with histological sections for entomology, heating them and
applying Toluidine Blue .5%, and my sections come out nicely stained, but

In the image processing community, there are discussions of edge
detection techniques.  For a simple case, imagine an opaque knife edge
with a uniform back light behind it. Further imagine there is a lens
that images the knife edge onto a pixel detector of a camera.

Does anyone know of a resource for Leitz Laborlux D parts?  I have a
used microscope that's missing a specimen holder/slide finger
assembly.  I purchased a "universal" X-Y mechanical stage finger
assembly from Ebay and made some adjustments to allow it to clamp onto

Only visit:
http://hvansari.googlepages.com    or
http://www.geocities.com/hamid_vasigh

Is Fermat's principle, the principle that states that the path that
light takes is an extremal, valid under the assumption that the
wavelength of light can't be ignored in a system, i.e. when
diffraction effects must be considered? My initial thought is no, but

Hey Guys...
There was an article in the Australian news today about the government
imposing bans on laser pointers.... When reading through it... it was
funny to see the lack of understanding and ignorance of those who are

Surprised this is the first report. A friend saw it and let me know
about it:
http://news.yahoo.com/s/nm/20080714/od_nm/russia_rave_dc_2

I am trying to find out if it would be possible to capture a hologram
of a bee or fly in flight using a pulsed laser.  Typical flap
frequencies are 200hz.  The light needs to be red or IR preferably as
the insects will not be spooked by it.

I am the volunteer coordinator for phytoplankton monitors.  We
recently got a small sum of money (not much 1K) to purchase scopes for
volunteers.
We use them to identify diatoms and dinoflagellates in coastal waters.

I'm new to this group, I'm from Hamburg, and I discovered this place via
SAM's Laser FAQ.
(OK, and to anticipate the questions, I know about the dangers of
coherent 1064 nm radiation, and I also tend to heed the precautions