Clearly 10,813,440. Gotta factor the words!

Sure. Line scan indoor units are extremely affordable, and some cost less that $20, sold as spare parts for robot vacuum cleaners. Outdoor units (with higher ambient light tolerance and longer range) are an order of magnitude more expensive, but also available.

Here is some detailed information about low cost units: https://github.com/kaiaai/awesome-2d-lidars/blob/main/README...

Depends on your budget and the resolution you need.

E.g Livox mid 360 https://store.dji.com/en/product/livox-mid-360

I haven’t done it myself but I’ve heard of people harvesting LiDAR units from their old/broken robot vacuums.

Check out PiLIDAR for one of many options:

https://github.com/PiLiDAR/PiLiDAR

> There's no way a sensor can tell if a signal was from its own origin?

https://ui.adsabs.harvard.edu/abs/1978ntc.....2...18F/abstra...

https://apps.dtic.mil/sti/tr/pdf/ADA218226.pdf

> An increasingly popular modulation scheme is Binary Pseudo Random Phase Coding (BPRPC), whereby the phase of the transmitted signal is switched between 0 and 180 under the control of a binary pseudo random sequence

this applies straightforwardly to lidar

basically: optical CDMA or DSSS

spoofing replay may still be a concern

Typically you use a pulse train and filter your train from the noise

If one lidar hits another, it will result in at most one bad reading (perhaps a bad column?). This can likely be filtered, or a bad scan (360deg) can be altogether rejected and the data predicted using models based on past sensor readings.

Worked adjacent to the AV space 5~ years ago. This wasn’t my area but I remember learning that this was a robustly solved problem long ago.

I guess phase and timing sensitivity help a lot, because it's unlikely that another emitter will perfectly match your emission/detection duty cycle. It's also hard to get hundreds of cars at one intersection, because cars are very big.

The key terms in your literature/patent search should probably be "Crosstalk" and "multi-LIDaR".