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What does "solid state" here mean? If i am not blind the aryicle doesn't explain that, only that it is cheaper.
by ralfd 10y ago
What does "solid state" here mean? If i am not blind the aryicle doesn't explain that, only that it is cheaper.
- coryrc 10y agoBy 'lidar' they mean '2d depth imager using lasers', which has historically been done with a fixed laser and a physically moving galvanometer. Solid state is to get rid of the moving galvanometer.
- mrfusion 10y agoReplacing it with what? It seems like something would have to be moving.
- gallamine 10y agoThere are many techniques for optical beam steering. It some cases you can use MEMs devices (like DLPs) or you can apply a voltage across a optically clear material that changes its properties under the electric field. This is used to bend the light in certain directions (think of an electrically controllable prism.)
- ethagknight 10y agoMEMs (as in a DLP tv) seems less than an ideal for the abuse a vehicle takes. Curious if the other option you mention is similar to a cathode ray tube?
- web007 10y agoIt depends on the implementation, the concept seems fragile but they can be amazingly resilient. There are a bunch of MEMS accelerometers that support ranges in the 10s to 100s of Gs.
- hwillis 10y agoSquare cube law. The mass (cube) of microscopic features is very small compared to their surface area (square), which dictates how thick their connections are. That means they have very little inertia and as long as they aren't scratched or wet they're very resilient. Electro-optic materials are more like LCDs. Light interacts with the material and the material interacts with electricity. In a cathode ray tube there are electrons, not light, and they interact directly with the electric and magnetic fields. CRTs also need a dozen-odd fields to form a good beam, or 30+ for things like electron microscopes.
- hwillis 10y agoDon't forget optical nanoantennas! Essentially a wiggly waveguide- you set up a standing wave inside it and light exits the wiggles at a specific angle, which can be altered by changing the phase of the standing wave. By having hundreds of wiggles you average out the fabrication error in any individual wiggle and produce an extremely controllable beam. Of course they're still working on the coherent part.
- ajuc 10y agoThere are 3d radar systems where nothing moves, instead the signal is shaped and directed using precisely timed small signals sent from an array of separately controllable antennas. Maybe light can also be done like that? I mean - obviously you could just create a stationary disc with lasers mounted all around it and switch between them electronically, but that hardly seems cheaper.
- Someone 10y agoSee https://en.wikipedia.org/wiki/Phased_array https://en.wikipedia.org/wiki/Phased_array. Visible light is radio, just with different wavelength, so the principle is the same. The much, much smaller wavelength (centimeters vs sub-micrometer) makes it harder to build a device, though.
- sohkamyung 10y agoThis article [1] goes into some detail of what "solid state" means. I hope it helps to answer your question. [1] Velodyne Says It's Got a "Breakthrough" in Solid State Lidar Design (Dec 2016) [ http://spectrum.ieee.org/cars-that-think/transportation/sensors/velodyne-announces-breakthrough-in-solid-state-lidar-design http://spectrum.ieee.org/cars-that-think/transportation/sens... ]
- JulianMorrison 10y agoIt means "not a big spinny thing that looks like an old police light on top of the car".
- runeks 10y agoAs far as I'm aware "solid state" always means "no moving parts", at least when used to describe electronic devices.
- cjhanks 10y agoThere are some basic diagrams from Quanergy [1] (page 9). [1] http://on-demand.gputechconf.com/gtc/2016/presentation/s6726-louay-eldada-quanergy-systems.pdf http://on-demand.gputechconf.com/gtc/2016/presentation/s6726...