High Beam Divergence

[BiasP11]

I recently bought an IR diode with high beam divergence (12 x 28 degrees rectangular). Unfortunately, the module I own has a focal length of about two inches and a lens diameter of 1 inch. This means that about half of the light is not focused and instead scatters around inside the module.

I thought to move the lens closer by cutting off a piece of the heatsink, but that would result in a diverging beam when the diode is closer than the focal length.

To remedy that, can I add another convex lens?

How else can I solve this problem?

 

[steve001]

Two ways.
1. Replace this lens with a larger diameter longer focal length lens
2. Buy or construct an IR beam expander

 

[Cyparagon]

Yes, you could add another convex lens. I would put it in a standard module if I were you though. 2 inch focal length is not laser material.

 

[Roam]

The laserbeam expanders are usually, I think, a convex and a concave lens put together. Since the concave is negative the whole system would be afocal, this is useful esp if you have a high power beam.

 

[steve001]

I recently bought an IR diode with high beam divergence (12 x 28 degrees rectangular). Unfortunately, the module I own has a focal length of about two inches and a lens diameter of 1 inch. This means that about half of the light is not focused and instead scatters around inside the module.

I thought to move the lens closer by cutting off a piece of the heatsink, but that would result in a diverging beam when the diode is closer than the focal length.

To remedy that, can I add another convex lens?

How else can I solve this problem?

Can you post some photos of this unit?