Lens that will make the rays parallel to each other

[kishushah]

i need a lens that will make the rays parallel to each other & focal point at infinite.without much loss in the intensity.collimator lens kind of action but not at the cost of intensity.

 

[K^2]

Very easy. A lens with a focal point at infinity is called a window.

 

[kishushah]

See the fig(attachment).I want to achieve this(shown in fig).

 

[mikeph]

That's just a normal lens, ray lines are independent of the direction of light.

I didn't realize collimators had any loss of intensity, are you using laser light or just a point source?

 

[kishushah]

That's just a normal lens, ray lines are independent of the direction of light.

i am not getting this.



Its not laser light it is the output from a parabolic antenna.with the beam angle of about 10-15degree.

 

[|squeezed>]

I 'm not sure i fully understood your question but you try using two lenses.
The 1st (focal length f1) to focus the light at a point and the 2nd (focal length f2) to get a parallel ray output.
The 2nd lens must be placed with its focal length at the focus point of the 1st i.e., at a distance f1+f2 from the 1st.

 

[mikeph]

What frequency are we talking about?

 

[kishushah]

microwave.have heard somewhere all the emwaves have the same properties as light.parabolic antenna is an example of that,as reflection of radio-microwaves is observed here just like light.