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from the ongoing-quest-to-capture-the-Roadrunner dept.
Light shaken and stirred to help autonomous vehicles better scan for nearby fast-moving objects:
A self-driving car has a hard time recognizing the difference between a toddler and a brown bag that suddenly appears into view because of limitations in how it senses objects using lidar.
The autonomous vehicle industry is exploring “frequency modulated continuous wave” (FMCW) lidar to solve this problem.
[...] FMCW lidar detects objects by scanning laser light from the top of an autonomous vehicle. A single laser beam splits into a comb of other wavelengths, called a microcomb, to scan an area. Light bounces off of an object and goes to the detector through an optical isolator or circulator, which ensures all reflected light ends up at the detector array.
[...] The technology integrates microelectromechanical systems (MEMS) transducers made of aluminum nitride to modulate the microcomb at high frequencies ranging from megahertz to gigahertz. The optical isolator that the team developed as part of this process is further described in a paper published in Nature Communications.
[...] “The stirring motion modulates light such that it can only travel in one direction,” said Sunil Bhave, a Purdue professor of electrical and computer engineering.
[...] Other transducers in the same technology excite an acoustic wave that shakes the chip at megahertz frequencies, demonstrating sub-microsecond control and tuning of the laser pulse microcomb or soliton.
Journal Reference:
Junqiu Liu, Hao Tian, Erwan Lucas, et al. Monolithic piezoelectric control of soliton microcombs, Nature (DOI: 10.1038/s41586-020-2465-8)
Hao Tian, Junqiu Liu, Bin Dong, et al. Hybrid integrated photonics using bulk acoustic resonators [open], Nature Communications (DOI: 10.1038/s41467-020-16812-6)
(Score: 3, Interesting) by JoeMerchant on Tuesday July 21 2020, @11:26PM (7 children)
Think about the implications for a second: that chip just oscillated millions of times while you took that second to think. The vibrational impulse motions are propagating from the source down the material at the speed of sound, which in solid silicon is 8433m/s, or 0.84cm per microsecond. Two of these things closely gapped and appropriately phased should make a nice micro-air pump.
🌻🌻 [google.com]
(Score: 0) by Ethanol-fueled on Wednesday July 22 2020, @12:41AM (3 children)
Whoooa, that's deep. Because that MHz crystal oscillator in my Sony Walkman just totally blew my brains out! I-uh....I'm oscillating! I'm gonnnna resonnnnnnnate! Aaaaahhhhhh! Uhhhhhh! Shewowies!
(Score: 1, Funny) by Anonymous Coward on Wednesday July 22 2020, @01:10AM (2 children)
My microwave (~2ghz) oscillated so fast that my weiner split and burst into flames
(Score: 0) by Anonymous Coward on Wednesday July 22 2020, @01:18AM (1 child)
That will teach you not to put your weiner in the microwave.
(Score: 2) by JoeMerchant on Wednesday July 22 2020, @02:35AM
Especially wrapped in tinfoil.
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Wednesday July 22 2020, @01:52AM (2 children)
> appropriately phased should make a nice micro-air pump.
So far all you have is an AC air pump which is roughly analogous to a loud speaker. To make a pump you need a foot valve / check valve / "diode-for-air" that also works at that high frequency.
(Score: 2) by JoeMerchant on Wednesday July 22 2020, @02:38AM
Think about a bedsheet, flop that bedsheet and send a wave down it, now - put another bedsheet above it and flop it in opposite phase, you've got a linearly travelling cavity not too different from a peristaltic pump, moving at 8443m/s.
🌻🌻 [google.com]
(Score: 2) by Muad'Dave on Wednesday July 22 2020, @11:21AM
I just learned about this [wikipedia.org] yesterday (YIL?) It's exactly what you describe. Of course Tesla designed it.