Adding an External Lens to Focus Beam

[GreenBean]

Hello all,
I am extremely new to lasers so I welcome all the help I can get! I recently purchased a laser (120mW 520nm 50m diving laser) for some underwater work. When I tested it out on land, I noticed it had quite a large divergence when shot over 200ft. Correct me if I am wrong, but I don't believe I can focus the laser without heavy modifications (opening it up and such). Would it be possible to attach an external lens to the laser to focus the beam/tighten the divergence?

Here is the link to the laser I purchased:
Diving laser 50 meters

Thank you in advance for your help!
Best,
GreenBean

 

[Alien Laser]

Sometimes the front cap can be unscrew and you can get to the lens and adjust the divergence, becareful it may be glued and very hard to open ?