Laser collimation

I’m using plano-convex lenses for both collimating and focusing. Is this the best approach, or should I consider different types of lenses for each job?

I’m not 100% confident that this will work as planned, and since the accuracy of the laser beam is critical, I want to be absolutely sure before moving forward. Any advice or suggestions from people who’ve worked with lasers or optics would be greatly appreciated!

Gaussianbeam

The collimating lens will take the diverging 20 µm beam and expand it to 20 mm, making the rays parallel. Once collimated, the beam shouldn’t expand further.

I’m concerned that the collimating lens might somehow treat the initial 20 µm beam as parallel and focus it instead of expanding it. However, from what I understand, the diverging nature of the initial beam should prevent this.

Collimated light source

Collimatinglens

I’m working on a project that involves collimating and focusing a laser beam, but I’m feeling a bit unsure about my setup and would love some feedback from anyone experienced in optics.

Is there any risk that the collimating lens will focus the 20 µm beam instead of expanding it? Or will it definitely expand the beam and make it parallel, as I expect?

After collimation, I want to focus the 20 mm collimated beam down to a 1 mm spot at distances between 10 m and 200 m using another plano-convex lens with a focal length of 500 mm.