[ATM] Wavelengths of light

[Dominic-Luc Webb]

On Fri, 3 Aug 2007, Dale Eason wrote:

> When testing with an interferometer then one needs to
> know the wavelength of the source.

Yes, although I noticed that I can get very nice Newton
rings with an orginary halogen bulb. I just needed to
check that my spherometer reference was flat within the
context of measuring sagitta with a dial indicator. I
think your glass has to be pretty close to flat to give
rings at all. Of course, you need to measure a few surfaces
against each other, but this has definitely worked for me
since the spherometer yields same sagitta as obtained by
an optical measurement.

Dominic