The researches appear to have relied on techniques like those recently used to identify the Somerton Man, a 75-year-old cold case in Australia:

https://news.ycombinator.com/item?id=35239993

https://spectrum.ieee.org/somerton-man

The researches appear to have relied on techniques like those recently used to identify the Somerton Man, a 75-year-old cold case in Australia:

https://news.ycombinator.com/item?id=35239993

https://spectrum.ieee.org/somerton-man

This is the first lidar company I've seen that says it measures the optical, rather than the electronic, time of flight.

They split the incoming light and modulate the other path, say with a ramp signal. The other path is left intact.

Then they measure both paths. They compare the modulated and unmodulated light and voila, you have time of arrival for the light pulse.