400 watts across 325 meters by laser - Page 1
Forum section: electronics / general

author: madires
author_rank: Super Contributor
timestamp: October 27, 2019, 10:30:40 am
content: 400 watts across 325 meters by laser:https://www.nrl.navy.mil/news/releases/researchers-transmit-energy-laser-power-beaming-demonstration

author: Simon
author_rank: Unknown
timestamp: October 27, 2019, 10:55:17 am
content: what was the efficioncy. With 400W they could not have been making coffees at great speed.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 27, 2019, 12:03:37 pm
content: 2kW in I think I saw somewhere.Would love to ask the CEO to stick his hand in the beam to demonstrate the safety they claim.

author: Simon
author_rank: Unknown
timestamp: October 27, 2019, 12:07:02 pm
content: pft? they claim that 400W concentrated beam is safe? my expresso maker uses 1.1 kW during heat so at the least they have to store the power and hope for less than 30% duty if you assume decent receiver conversion and running laptops.

author: StillTrying
author_rank: Super Contributor
timestamp: October 27, 2019, 12:29:47 pm
content: pft? they claim that 400W concentrated beam is safe?The vid says 400W DC into the DC-AC inverter, so probably ~2kW in the actual beam.In the US you've only got to mentionthe militaryandforward operations baseto keep the funding flowing, in the EU we have to mention green energy, graphene, nano-particles and sustainable, the idea itself doesn't have to be useful, practical or even work.

author: Simon
author_rank: Unknown
timestamp: October 27, 2019, 12:59:06 pm
content: Quote from: StillTrying on October 27, 2019, 12:29:47 pmOh great 20% efficiency, may as well use wires. They make claims about the wireless transfer to drones but the tracking and delivery to a moving thing that needs to keep pointing at the beam is 99% of the job so they have achieved absolutely nothing.QuoteTrue, I should have sought funding for my solar panels......

author: coppice
author_rank: Super Contributor
timestamp: October 27, 2019, 01:07:08 pm
content: Quote from: Simon on October 27, 2019, 12:59:06 pmThe military has a huge number of applications where wires don't cut it. 20% efficiency is satisfactory for most of them, as they bring huge savings in other ways, like allowing things to stay on station indefinitely.Quote from: Simon on October 27, 2019, 12:59:06 pmThe tracking issues have already been well researched by the US military, in their work on shooting down flying objects using lasers. They are actually pretty good at sending out a laser beam, and keeping it accurately aligned on a moving target. Its the receiving and using of the power by the target, rather than letting it burn a hole, which seems to be the focus of this new demonstration. If they can keep power flowing smoothly to one of their drones it could stay airborne indefinitely, and transform the business of surveillance.

author: iMo
author_rank: Super Contributor
timestamp: October 27, 2019, 04:53:58 pm
content: ..unless it is raining, snowing, foggy, dusty, or low clouds..

author: Brumby
author_rank: Unknown
timestamp: October 27, 2019, 10:47:12 pm
content: Safety is actually covered in the article. Nobody said nor inferred that the laser beam is safe in itself - but theoverall systemis safe. That raises questions about failure modes of the safety system and that would be the direction where my reservations lie.

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 28, 2019, 12:23:19 am
content: "the safety system is designed to detect objects before they ever reach the laser beam, and turn it off."I wonder what could ever go wrong with that.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: October 28, 2019, 02:48:33 am
content: Quote from: mikeselectricstuff on October 27, 2019, 12:03:37 pmThe mirror looks quite large. Hard to tell by eye, but I estimate a 150 mm wide beam. That's about 175 cm2, or (assuming a 2 kW beam) roughly 10 W/cm2, which you could safely pass your hand through ... quickly. Somewhat less concentrated than the heat from a candle, anyway.What it certainlyisn'tis eye-safe.

author: ejeffrey
author_rank: Super Contributor
timestamp: October 28, 2019, 03:17:06 am
content: I think AoE mentions an application of a light and solar cells to create an isolated power supply at the business end of a particle accelerator with several million volt acceleration potential. Of course on a smaller, less mobile scale than this, but the point is there are applications where you need to get the power there and the efficiency is secondary. If your alternative is not wires but batteries or generators you might be willing to put up with a lot.

author: coppice
author_rank: Super Contributor
timestamp: October 28, 2019, 03:35:32 am
content: Quote from: ejeffrey on October 28, 2019, 03:17:06 amFor decades people have been powering monitoring electronics sitting at extremely high voltages, by sending light through the air or an optical fibre to a photovoltaic cell at the monitoring electronics.

author: BravoV
author_rank: Super Contributor
timestamp: October 28, 2019, 04:35:58 am
content: Quote from: mikeselectricstuff on October 27, 2019, 12:03:37 pmWonder if they provide a loaner unit for Nigel Stanford.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 28, 2019, 07:52:53 am
content: Quote from: StillTrying on October 27, 2019, 12:29:47 pmMaybe EIRP, which is meaningless in the power transfer context.The actual, useable power must always be less than the DC input.Quote