Focus or parallelize the light from an LED

  • Thread starter Lexinas
  • Start date
  • #1
1
0
Hello, everyone,

I have a LED, 620nm, with a viewing angle of 20°. I would like to bring this light in a distance of about 20cm on a lens with as many photons as possible.
My idea is to position a converging lens between the LED and the lens. To be exact, I would position the lens at the distance of the focal length to the LED. To get as many photons as possible into the lens, the lens should be as close as possible to the LED so that as much light as possible goes through the lens and that would correspond to a very short focal length.

Are my considerations correct so far?

Best regards
Lexinas
 

Answers and Replies

  • #2
Drakkith
Staff Emeritus
Science Advisor
21,299
5,142
Yes, that's right. The closer, stronger, and larger the lens, the more light that you can intercept with it and redirect onto the 2nd lens.
 
  • #3
sophiecentaur
Science Advisor
Gold Member
2020 Award
26,541
5,573
A compound arrangement with two lenses could do what you want without needing a single large diameter, lens.

eBay has a selection of many different second hand SLR camera lenses you could play with and the cheapest lenses are only a few quid each. (Even the lowest spec lenses are actually pretty good.)
I do appreciate that you are not planning on building a whole Optics lab but you could find it interesting and get a result.

Do some sketches , using the dreaded 1/f = 1/u + 1/v formula. The first lens will form one virtual image behind the LED and the second lens could focus that intermediate image to a point where you want it. There are a host of possible solutions, depending on the lenses you can get hold of.
 

Related Threads on Focus or parallelize the light from an LED

Replies
3
Views
3K
Replies
5
Views
619
Replies
10
Views
1K
Replies
1
Views
6K
Replies
5
Views
12K
  • Last Post
2
Replies
47
Views
6K
  • Last Post
Replies
0
Views
5K
  • Last Post
Replies
10
Views
7K
  • Last Post
Replies
6
Views
3K
  • Last Post
Replies
3
Views
7K
Top