# Projector optics (help needed )

1. Sep 21, 2004

### sharp81

hi,
i am in need of help pretty quickly here.i will have to design a projector design using a fresnel lens and the projection lens.i need to find and derive the equations for the lenses and calculate the distances between the lenses and the lens and the screen.
this is what i require to have :
d1 - distance from the light source to the fresnel lens
d2 - distance between the fresnel and the projection lens
d3 - distance between the projection lens and the screen
f1,f2 - focal lengths of the fresnel lens
f3,f4 - focal lengths of the projection lens
In my case i know the values of the focal lengths and the distance between the light source and the fresnel lens.

i will have to find d2 and d3. also i need to find the net magnification factor for the light source which will be my object.
any help will be greatly appreciated.
harish

2. Sep 22, 2004

### maverick280857

Hi Harish

The equations you are looking for are standard equations that can be found on the Internet. Start by looking up google.com for fresnel lenses and their mathematical basis. You may not get exactly what you want but with a bit of hard work, you'll reach quite close to the desired form of equations.

Try normankoren.com (I am not sure if they have all this but the site is worth visiting anyway if you're interested in cameras/photography/lenses/optics).

Cheers
Vivek

3. Sep 23, 2004

### sharp81

i have looked over the net but havent found anything related to fresnel lens equations

4. Sep 23, 2004

### maverick280857

That I can't digest :-D....try googling it. Try copernic, webferret, etc.

5. Sep 24, 2004

### sharp81

i am thinking these are going to be my focal length equations tell me if they are right
f1 = d1
1/f2 = 1/d1 + 1/(d2+d3)
1/f3 = 1/d2 + 1/d3
Magnification = d3/d2