Natural Science Forum / Physics / Optics / November 2007

Many years ago, I understood from both theory and reality that thermal-
imagers were not capable of looking through (ordinary) glass windows, with
glass blocking just that (broad?) spectral range in which the imagers had no
sensitivity at all (hence also all using very expensive ...

On a Nikon scope of type L-Ke the illumination
is truly of the Koehler type. The filament of the
tungsten light is imaged onto the diaphragm of
the condenser lens and is centered and clearly

Anyone know a cheap source for the type of M12 plastic lens holder found on board cameras, in qtys
of 100s (maybe 1K if cheap enough)?
Best I've found so far are these :
http://www.ukaoptics.com/new.html#proto

I am sure that at some stage during my high school science education I
saw a picture rendered as it is actually projected onto the retina. I
seem to remember a relatively small circle of decent quality with most
of the image almost useless. I have (sadly) not continued my biology

Bob wrote in
http://groups.google.com/group/sci.energy/msg/5acc0e5bc17726a6 :

Does anyone know of any good systems for sale?  I have a couple people
interested.
Thanks.
--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ 

i'm looking for a system able to make rotations with a resolution of 2
microradiants or less. Probably a system based on piezo will work
fine. The system should have the following features:
-angualar rotations into interval of 5 milliradians at steps of 2

Got a power supply (A100) for my Omnichrome HeCd (74xx) head. Fired it up
today.
First, it started well, plasma discharge went on but during heat-up phase,
the "over temp."

I noticed there are different definitions of Beer's law. In analytical
chemistry it is often defined with the basis 10:
I/I0 = 10^(-aL)
where a is the absorption (extinction) coefficient.

Hey all,
Does somebody know valuation of axial dimensions of the human eye? I
mean the range between lens and retina. I usually use eye model with
17.25mm between the lens and retina, but in myopic and hyperopic case

Here in italy there is one guy that is sure he has found the quote of
an airplane by shining on it with a 5mW green laser.
He says:
We pointed a chemical tanker with a laser pen. It is the proof that

let's suppose a wavefront has only astigmatism (Z4, Z5) and no other
aberrations. What's the ratio between RMS and PV in this case?
Thanks,
Michael

Has anyone tried this at all.  I was thinking specifically for
engraving wood.  What Equations should I look at to decide whether
there is enough irradiance to cause oblation?
If I can get this to work is it viable to attach it to an old time

I have a metal foil of peculiar shape with about 3-4 cm^2 area
perforated with a grid of roughly 0.1mm holes on 1mm centers.
I need to provide a reasonably uniform (50% will do) luminous surface
behind the holes.  There are fairly tight mechanical constraints on what