[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: MARS HYBRID DESIGN II (First Draft)
- To: bmansur <bmansur@oc.edu>, David <David@InterWorld.com>, hous0042 <hous0042@maroon.tc.umn.edu>, jim <jim@bogie2.bio.purdue.edu>, KellySt <KellySt@aol.com>, lparker <lparker@destin.gulfnet.com>, rddesign <rddesign@wolfenet.com>, stevev <stevev@efn.org>, "T.L.G.vanderLinden" <T.L.G.vanderLinden@student.utwente.nl>, zkulpa <zkulpa@zmit1.ippt.gov.pl>
- Subject: Re: MARS HYBRID DESIGN II (First Draft)
- From: Brian Mansur <bmansur@oc.edu>
- Date: Tue, 05 Mar 96 17:21:00 PST
- Encoding: 46 TEXT
----------
From: T.L.G.vanderLinden
To: KellySt; stevev; jim; zkulpa; hous0042; rddesign; David; lparker;
bmansur
Subject: Re: MARS HYBRID DESIGN II (First Draft)
Date: Tuesday, March 05, 1996 11:49PM
Brian 5:15 PM CT 3/5/96
>Brian
> How about putting a Fresnel lens in the path to TC to refocus our beam.
The >lens could be of the thin variety, although I believe we would have
some >power losses through the lens.
>Tim
>As far as I know Fresnel lenses are not really lenses, that means they
don't
>magnify or bundle lightrays.
>These "lenses" are constructed in such a way that all outgoing light has
the
>same phase at a predetermined distance (the "focusing" distance). This way
>the cancellation of two waves with a 180 degree phase difference is
prevented.
>So this method is only valid when normally INTERFERENCE makes de total
>brightness different.
All I know about Fresnel lenses is what my textbook (now in front of me)
says. Since this is a non-calculus based book, it may be leaving important
detail out. The following is a partial excerpt of its treatment of Fresnel
lenses:
"To focus or to produce a large beam of parallel light rays, a sizable
converging lens is necessary. The large mass of glass necessary to form
such a lens is bulky and heavy; moreover, the thick lens absorbs some of the
light, and is likely to show aberrations . . . . Fresnel recognized that
the refraction of light takes place at the surfaces of a lens. Hence, a
lens could be made thinner -- even flat -- by removing glass from the
interior as long as this was done without changing the refracting properties
of the surfaces."
Note they are "easily molded from plastic."