26 Apr
2010
26 Apr
'10
1:05 p.m.
On Mon, Apr 26, 2010 at 12:26 PM, Canopus56 <canopus56@yahoo.com> wrote:
So, what's an ethalon and how does the Lunt incorporate into a refractor design?
Essentially it's just narrow-bandwidth filter, working on the same principal as most of the "interference" filters in the amateur astronomer's arsenal (LPR, H-a, H-b, O-III, etc). A specialized type of Fabry-Perot interferometer. Thes spacing between the two reflective surfaces determines the wavelength bandpass.