Basic Beam Expander

I'm trying to build a basic beam expander. I am a commercial fisherman and I'm looking to build a prototype signaling device.

The idea is to use PVC and lenses salvaged from old optics I have laying around. I have done allot of searching and have read various articles, including some of the DIY threads on the forum.

But since I am a total noob, I have some possibly dumb questions.

Dumb Question:

I bought this 100mW green laser from Lazerer thinking it would fit inside a PVC housing well LZTN - 532nm 100mW Smallest Green Laser Pointer the laser does not focus.

Do I need to remove the lens from this Laser in order for it to work with my optics? In my initial tests with a Galilean expander design it seems I can only replicate a narrow beam not much bigger as its normal.

Also how concerned should I be with looking at the reflected dot of this laser at close range off a white wall? I do have eye protection, but I need to periodically take them off to see the results of my tests.

Removing the front lens will make a larger uncollimated beam. It'll probably help with the overall size of the expanded beam, but you'll need to make adjustments in your expansion optics to collimate the beam once more.

The reflected spot should be okay for viewing so long as it is hitting a diffuse surface and you're not too close. If you're expanding the beam, it'll reduce the danger even more. Make sure your stuff is well mounted though; you don't want the laser rolling off.

I see no point in making the beam smaller at a distance. Do you mean turning it into a flashlight-like beam? If so, why not just use a flashlight?

I think he's trying to make it bigger but the beam expander doesn't do much for such a small beam.

Alerik said:

I'm trying to build a basic beam expander. I am a commercial fisherman and I'm looking to build a prototype signaling device.

The idea is to use PVC and lenses salvaged from old optics I have laying around. I have done allot of searching and have read various articles, including some of the DIY threads on the forum.

But since I am a total noob, I have some possibly dumb questions.

Dumb Question:

I bought this 100mW green laser from Lazerer thinking it would fit inside a PVC housing well LZTN - 532nm 100mW Smallest Green Laser Pointer the laser does not focus.

Do I need to remove the lens from this Laser in order for it to work with my optics? In my initial tests with a Galilean expander design it seems I can only replicate a narrow beam not much bigger as its normal.

Also how concerned should I be with looking at the reflected dot of this laser at close range off a white wall? I do have eye protection, but I need to periodically take them off to see the results of my tests.

Click to expand...

To the bold text.
Beam Expanders are add on optical devices. Get the hint ?

That depends on the distance of the Rayleigh Range created by the lenses you use. Some Ranges can be short and others can be meters and meters + (yards and yards +) long. Actually there's no theoretical limit, just practical ones. The Rayleigh Range is the distance over which the beam expands 1.4 times its original diameter. After that point the beam expands in a normal fashion- linearly, like a flashlights beam. For very long ranges surfaces of greater distances are needed to collimate the beam for lowest divergence. That applies to any range actually.