[Laser] Re: Fresnel lenses

[Tim Toast]

hi paul
i'm using a short focal length mirror for some NLOS
experiments and it has a FOV of about 0.7 degrees or
so. (247mm focal length and 3x3mm detector)

here's a formula for calculating field of view:

F = (57.3/FL) x D

where:
F= field size in degrees
FL = focal length of lens or mirror in millimeters
D = detector or film dimension in millimeters

for your example:
57.3 / 400mm = 0.14325
0.14325 x 2.5mm = 0.358 degrees FOV

in milliradians:
milliradians = degrees x 17.45
0.358 x 17.45 = 6.247 mR FOV


>
>From: "Paul Cianciolo" <Paulc at snet.net>
>Subject: [Laser] Fresnel lenses
>
>Folks,
>
>I wonder if anyone has used a 10" or so diameter for
>a receive antenna?
>
>The problem I see is the relatively short focal
>lengths.  This combined with the a 2.5 mm dia.
>detector makes for a pretty wide FOV.
>The fresnel's have tried have not been the most well
>focused lens's.
>Just curios.
>3DLEN.COM perhaps?
>What are you guys using as a FOV for NLOS receivers?
>W1VLF
>PauLC
>



Tim Toast
http://www.aladal.net/toast/exp.html


		
__________________________________ 
Discover Yahoo! 
Get on-the-go sports scores, stock quotes, news and more. Check it out! 
http://discover.yahoo.com/mobile.html