From: "CSC" 
To: "Atm" 
Reply-To: "CSC" 


Ray:

What a great name for an amateur optician!

That's diffraction from the grating and from the knife edge.  If light was
discrete particles, it wouldn't happen, maybe, but with waves.....

This smearing suggests using interferometry where you use the diffraction
effects.  I notice while testing spheres using ronchi, and using
monochromatic light, the diffraction images at certain grating locations
can be made to overlap and give very distinct lines.  The FINER the grating
the better, whereas with white light, the higher order images from such a
grating are a nuisance.

Then there's the shearing interferometer a la Peter John Smith.  Too simple
to discuss here.  check his web page.

Colin

-----Original Message-----
From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of
J-Engineering
Sent: Tuesday, January 21, 2003 1:38 PM To: atm{at}shore.net
Subject: ATM Foucault and Ronchi Testing



Hi All,

Could someone direct me to an online source for Foucault and Ronchi
testing.  What I'm looking for is how to make the images look cleaner, not
how to interpret them.

Two immediate problems in the images are: 1)  In the Ronchi test I see a
bright smearing of the image perpendicular to the lines of the grating .
Smearing extends several mirror diameters to the sides of the mirror. 2)  
In the slitless Foucault test I see a very large number of light
lines parallel to the knife edge.  These lines move when my eye moves.

In both tests, the grating or knife are about 3 mm ahead of a frosted
window.  There is a 3 mm dia hole between window and grating or knife edge.

Mirrors are spherical for now.

Thanks for any help,

Ray

--
Ray Jurevicius
www.J-Engineering.com
Metal Forming Simulation

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