There are easy ways to protect a LIDAR against that, but I don't think Velodyne is doing them yet. The duty cycle is low; a ranging operation takes under 1us, and typical cycle rates are 100Hz. So each beam is live only about 1/10,000the of the time. A simple denial jammer thus needs far more power than the pulsed laser used for ranging. A simple denial jammer looks like a target at zero range, so you know you're being jammed. Note that jamming must the same color as the ranging laser; everybody has narrow-band interference filters that only pass a very narrow color band. That's why this works in sunlight.
To defeat a synchronous jammer, the LIDAR only needs to add some random variation in the transmit timing. Then the jammer won't know when to be on. With some random variation, synchronous jamming looks like noise, rather than a solid false reading.
This new MIT system requires that the received light be in phase with the laser beam at the light coherency level. That makes it reasonably immune to anything other than a laser that can sync to a narrow light pulse. Not sure that's even possible.
Even if each ranging operation is fast, they will be scanning it around, so I suspect the effective duty cycle will be higher. Light bounces all over the place, so two sensors could still interfer even if they are measuring two different paths in space. It can probably be resolved with careful, expensive, and coordinated engineering, but I would expect the first gen sensors to interfere with each other just as primesense cameras do unless the authors explicitly claim otherwise.
To defeat a synchronous jammer, the LIDAR only needs to add some random variation in the transmit timing. Then the jammer won't know when to be on. With some random variation, synchronous jamming looks like noise, rather than a solid false reading.
This new MIT system requires that the received light be in phase with the laser beam at the light coherency level. That makes it reasonably immune to anything other than a laser that can sync to a narrow light pulse. Not sure that's even possible.