Natural Science Forum / Physics / Optics / April 2005

I just bought some powerful IR LEDs that have a narrow beam, the guy says
15-20 degrees, no specs, hmm.  Anyway, I'd like them to be more diffuse say
60 degrees 2x half maximum.
Should I just lightly sand the top of the lense?

My brightfield images always have a pale "salmon coloured" cast to the
background. I generally run the lamp at around 6-7V, but the issue
persists at 12V too - so I don't think it can be a colour temperature
thing(?). Visually, the background looks perfectly white to me.

When constructing a Galilaen beam expander which is the lens of choice,
a Plano-concave or Bi-concave?
Thanks
Steve

Anyone have the pinout for the Cambridge 6580 scanner amp for the 6800
series?  I need the input pin out, output connector pinout and diagram
of adjusment pots would be great as well.
Thanks

A question:
Don't understand why the Absorption ocurrus at Higher wavelengths (4mm
-
20mm) while the scattering influences largely the shorter wavelengths?

I'm looking for a little advice from people who have purchased a
greenie, and what they recommend.
Who makes (sells) a good quality unit, for a reasonable price (under
$100)?  I'd like to stay at 5mW for U.S. legality.

I have seen various galvos for sale on ebay, some seem quite
reasonable in price.  I know pairs of these are used along with an
F(theta) lens to do laser marking with CO2 lasers.
I do some home CNC stuff and have a CO2 laser, I want to know how

Neat article on beating the diffraction limit:
http://optics.org/articles/news/11/4/17/1?rss=2.0
I guess the "negative refractive index" refers to phase, and not group,
velocity.  More info: N. Fang et al., Science vol. 308, p. 534 (22 Apr.

I've got a Melles Griot 58-GSD-309 3W green DPSS laser system here that
was removed from a dental laser system.  This is the dual beam type and
has an assembly connected to the output end of the head which I presume
combines and collimates the beams, although it's much shorter ...

Need a macro/microscope lens with widest possible working distance.
There has been the Katoptaron LDM-1 and the MRM-1 by Infinity Optical
and the Questar M1.
Any ideas, offers, sources, documents most welcome!!

I have noticed binoculars being advertised with the 'latest BAK 6 prisms'.
I've heard that BAK 4 are the best and BAK 7 are the most common, but has
anyone heard of BAK 6 and know if they are of good quality?
They seem to be of chinese manufacture, and i'm wondering if they are a

http://www.usedmicroscopes.co.uk/budget%207%20big.html
Thanks

What if the second filter is not there (read on)? What is the purpose of
this little element?
I still measure a healthy output power on this laser.
The coherent 532-200 DPSS laser has a blue-green IR blocking filter for

I'm running a 30W CO2 laser system and was wondering if I could use an
uncoated focus lens. The current lens is ZnSe, 19 mm dia and 50 mm
focal length.
What would be the effect on the transmitted power?

Do something with your laser!
I've put together a page showing off my new goo
projector prototype. For $20-30 I'll show you how
to build this neat little gadget which allows you