Yes, there's nothing about the resolution. You can get single-beam scanners for about that price now. If it's only a few beams, it's not a big deal. You can get a small number of beams automotive LIDAR from Continental right now.
If you took a single-beam LIDAR and reflected it off a reflective prism where each face is at a slightly different angle, you'd have a somewhat slow multi-beam scanner with only one emitter and detector. I looked into doing that for the DARPA Grand Challenge, We were thinking of a mod to a rotating scanner used in laser printers to scan the page. There are optical companies that can cut and polish custom prisms. We were too small a team to build our own scanner, though.
Another way to do it is to mount a 2D LIDAR to scan in the vertical plane, and then pan that around. A 180 degree pan will net you a dome/spherical volume (although in a slow manner).
You could do this easily with cheap parallax sensors (like you find on Neato vacuum cleaners, and which are now sold as separate units - RPLidar and such). This has also been done using SICK coffeepot-style 2D LIDAR units (such rigs tend to be large and heavy, tho).
Something I've often considered is the idea of a "stochastic" scanner - that is, don't worry about strict angles, just let the sensor scan at random angles, and note the angle and reading. Over time you'd build up a complete scan. Just an idea I've rolled around in my head; the idea was to eliminate the need for syncing and timing of the scan hardware (2D or 3D), at the price of not necessarily getting a complete perfect scan all the time. It was something of a thought experiment I had while thinking up ways to DIY a LIDAR sensor in a very cheap manner, beyond what has already been done.
CSIRO did something like this with their Zebedee system[0], basically a Hokuyo 2D spinning lidar on a spring on a handheld stick. I love this from a design perspective, because it's very usage focused. You already have a human walking around site scanning, and a spring like this gives you the pitch and roll for "free", compared to panning it using an (expensive/heavy/clunky) electromechanical mechanism.
This has also been done using SICK coffeepot-style 2D LIDAR units (such rigs tend to be large and heavy, tho).
Yes. Had one of those once. Worse, we had the weatherproof SICK unit, which is even bigger. We prepared for the DARPA Grand Challenge expecting much more off-road. Way too much skid plate stuff, armored cables inside mesh washing machine hoses, sensor cleaning with washer fluid and compressed error, stuff like that. Totally unnecessary, as it turned out.
Something I've often considered is the idea of a "stochastic" scanner
Someone sells one of those. There are two unsynchronized scan axes. More for stationary than for moving applications.
Do you happen to know if there's a LIDAR system (I'm aware that many of them just use LEDs) that operates at UV frequencies near the transition to visible?
I'm looking for a LIDAR that can provide basic terrain and obstacle mapping underwater.
If you took a single-beam LIDAR and reflected it off a reflective prism where each face is at a slightly different angle, you'd have a somewhat slow multi-beam scanner with only one emitter and detector. I looked into doing that for the DARPA Grand Challenge, We were thinking of a mod to a rotating scanner used in laser printers to scan the page. There are optical companies that can cut and polish custom prisms. We were too small a team to build our own scanner, though.