4 ms·
Wireless laser power transmission using a gain medium between retroreflectors
- tlb 8y agoI don't see how you can use a retroreflector as one end of a laser cavity. They destroy coherence, since the path length is different depending on where each photon hits the reflective element. Don't lasing mediums require fairly coherent photons for stimulated emission to work?
- aidenn0 8y agoI don't think this will be a problem. A classic gas laser can have variations of more than 1 wavelength in its cavity without any issues. I believe this was one reason for the relatively short coherence length of HeNe lasers, but I could be wrong.
- cottsak 8y agoI bet you the lasers in these transmitting devices will not be gas but small solid state units. As this becomes more popular, like surface-mount camera dies, these SMD IR laser diodes will become smaller and smaller.
- aidenn0 8y agoThey are probably using semiconductor units (with lasers "solid-state" usually refers to non-semiconductor solid lasers, such as ruby lasers). My point with HeNe lasers was that having variations in the cavity length is not a problem for lasing.
- deleted 8y ago[deleted]
- analog31 8y agoI think the path length may be constant. Retroreflectors can be used in Michelson interferometers. https://patents.google.com/patent/US5309217 https://patents.google.com/patent/US5309217
- tlb 8y agoI stand corrected.
- stevemk14ebr 8y agowireless power exists already? Is this the same tech: https://www.youtube.com/watch?v=YeNXRD8eziA&t=0s https://www.youtube.com/watch?v=YeNXRD8eziA&t=0s
- aidenn0 8y agoNot clear how this couldn't inadvertently fry my eyeballs. Even very low-powered IR lasers are regulated because there is no blink-reflex.
- cottsak 8y agoRead the patent or watch the video https://www.youtube.com/watch?v=YeNXRD8eziA&t=0s https://www.youtube.com/watch?v=YeNXRD8eziA&t=0s In simple terms, the laser transmitter, the laser receiver and the beam that is used introduces a feedback mechanism that the transmitter can employ to immediately detect an unsafe condition and cut the high power (infra red) laser transmission. The response is so fast that the risks to damaging eyes, etc are acceptably low.
- aidenn0 8y agoI'm still trying to figure out how that would work with e.g. a piece of glass sitting at an angle other than parallel to the wavefront. That would pass most of the light while reflecting a collimated beam that is much more powerful than allowed for direct laser emission. Consider the situation where a flat piece of lime glass is in the way at an angle that reflects 1% of the light and passes the rest. With a 3W beam, that would reflect 30mW of laser light which as a direct emitter would be class 3B.
- cottsak 8y agoI'm more confident now that it's probably very dangerous and may not get the FDA approval. If they do it will be trickle charging. https://www.youtube.com/watch?v=2bXjn3wwM8o https://www.youtube.com/watch?v=2bXjn3wwM8o