Focus mod for green lasers: some questions

[zerafiel]

So is there anything I need to know to do a focus mod for a 532nm laser or can I just take an already collimated laser and...

slap 2 lenses in front
center the beam on the lenses
align the lenses at ~2f
make one of the lenses adjustable

Is this all there is to it?

Some questions...

What sort of lenses are recommended?
Plano-concave?
Can I just use the plastic lenses from Aixiz housings?
Or are they only coated for 650nm?
How about Aixiz glass lenses?

Any help would be appreciated.

 

[o_DEATH_ANG3L_o]

Depends on what you are trying to do here. If you are trying to get a nice tight beam to burn stuff, and you dont care about carrying a magnifying glass around then just use that.

 

[zerafiel]

The idea is to make a module attached to the laser. So a magnifying glass is kinda big and unsteady. Besides I can get the same effect using a lens cap set which I have. Just that the focal length is fixed and irritatingly near.

 

[Gazoo]

I have no idea how well this lens would work, but optotronics has a 6mm diameter 4000mm focal length lens.

Go here and scroll down...

http://optotronics.com/optics_kit.php

 

[zerafiel]

Thanks for the link. hmm 4meter double convex could be very useful but the optotronics site doesn't say anything about the material or if it is AR coated.

I think I will go with a Galilean beam expander design with a fixed plano concave and adjustable convex/plano-convex lens

Maybe nova's -8mm plano concave + a 26mm meniscus from nova might give me a 3x beam expander

other options 30mm plano convex from nova
or 35mm double convex from opto (don't think I'll spend up to $25 though)