just saw an article about power transmission over distance using laser: https://www.allaboutcircuits.com/ne...s-power-transfer-nearly-100-feet-using-laser/

of course such things are interesting and it would be nice if more of numerical data was shared. efficiency is one key factor in power transmission.

linked article
https://www.optica.org/en-us/about/...chers_use_infrared_light_to_wirelessly_trans/

states that 400mW of laser light output produced 85mW of electric power. typical 400mW output laser draws some 50W of power.
so from estimated 50W input they successfully got 835W 85mW output at 30m making efficiency about 0.17%. Then the picture shows room full of people with laptops and smartphones all getting this power wirelessly. the picture suggests that devices are in use but lets say they are only being charged, that would still need some power... also lets say that charging is pretty slow and only needs 20W. to get that 20W delivered, 12kW is needed for transmitter powering laser that has 235W of optical output. I know they are pumped to tell about their breakthrough but c'mon... it will take some time for portable devices to get down to 30mW of charging power. I would not like to have 12kW heater over my head and most certainly do not want to be in the same room with such laser...

 

so from estimated 50W input they successfully got 835W output at 30m making efficiency about 0.17%.

I think there is a typo or this is an overunity article.

 

sorry, and thanks for reply. it is a typo... corrected to 85mW.

 

If everyone is going to install laser power receivers (photovoltaic cells) on their laptops and cell phones to forego the inconvenience of plugging them into the wall, it seems simpler to just install skylights than to mount a fiber laser to the ceiling. Fortune cookie says the forecast includes inexplicable localized sunburns and involuntary tattoo removal.

 

If everyone is going to install laser power receivers (photovoltaic cells) on their laptops and cell phones to forego the inconvenience of plugging them into the wall, it seems simpler to just install skylights than to mount a fiber laser to the ceiling. Fortune cookie says the forecast includes inexplicable localized sunburns and involuntary tattoo removal.

The referenced experiment proved that light from a laser also has energy like sunlight. Nothing more from my point of view. They may has well focused sunlight with a big parabolic mirror and a focused it down to a little beam. An MIT research group showed that the output of most types of solar panels can be boosted well beyond rated current by focusing sunlight to increase flux density by factors of 3 or 4.

 

If everyone is going to install laser power receivers (photovoltaic cells) on their laptops and cell phones to forego the inconvenience of plugging them into the wall, it seems simpler to just install skylights than to mount a fiber laser to the ceiling. Fortune cookie says the forecast includes inexplicable localized sunburns and involuntary tattoo removal.

Wouldn’t it be even more sensible to have a solar panel and go sit outside?
Who are the idiots at AAC that report this nonsense as it if is real science? The scientific literacy of journalists leaves a lot to be desired.

 

This part of the experiment may have been overlooked:

“While most other approaches require the receiving device to be in a special charging cradle or to be stationary, distributed laser charging enables self-alignment without tracking processes as long as the transmitter and receiver are in the line of sight of each other,” said Ha. “It also automatically shifts to a safe low power delivery mode if an object or a person blocks the line of sight.”

The novelty is the distributed laser charging, which is a fascinating idea. They are making no claims that the current efficiency is sufficient for a practical device, only demonstrating that distributing the laser is possible, as a first step.

 

There was a similar daft idea around a couple of years ago using high powered ultrasonics - I think it operated at 55kHz at the equivalent of about 120dB well above the human audio range.
However, they had failed to take into consideration is that 55kHz is within the hearing range of cats and dogs.

 

Highly innovative, they added an object tracking camera gimbal to an IR laser to keep the laser pointed at a solar panel to inefficiently. Think of the power that could be saved if wire was used.

A "typical" 4K object tracking camera - $200
https://www.obsbot.com/store/produc...MI5ajPsbS8-gIVp3NvBB1VKwdCEAQYBCABEgIB3PD_BwE

 

I’m reaching hear but transmissions from another location in space might be broadcasting at this moment, using pulsing light embedded data transfer.

One requirement is to decode the message, mountains of data could be transmitted into that region of space.


kv

 

Highly innovative, they added an object tracking camera gimbal to an IR laser to keep the laser pointed at a solar panel to inefficiently. Think of the power that could be saved if wire was used.

A "typical" 4K object tracking camera - $200
https://www.obsbot.com/store/produc...MI5ajPsbS8-gIVp3NvBB1VKwdCEAQYBCABEgIB3PD_BwE

No, they spatially distributed the laser with one has as the transmitter and the other the receiver. While the lede is buried in the story, it is the demonstration of a distributed laser that is the innovation. There is not claim of practicality, this is basic research in anticipation of efficiency improvements and other components.

I don't understand why people jump to the conclusion that a university research program is producing papers on trivial topics that a moderately informed person could spot instantly as vacuous. It's true that press releases written by university PR departments can exaggerate and conflate things, but there will always be something that can be peer reviewed.

 

Well, when I got my PhD at a top-20 science & engineering school, there were plenty of projects that weren't quite working as planned, Since a PHD degree needs a positive result (not a failed experiment), some late 3rd year, 4th year and 5th year students start grasping at straws. They publish the little parts of the project that worked (no matter how stupid or inefficient or vacuous they may have been) because nobody has time to start a new project. The goal was to get their two reviewed publications into the literature, employers never read them, they just count them. I did a post-doc at a very prestigious school and thought things would be different - but it was the same there too. Some research results are stupid.

Do you know what they call the graduate student who barely defends their project in front of their committee? A PhD.

 

Another story...
A famous professor became head of a national professional society in the late 1980s/early1990s. His research program suffered. He skipped writing research grants for three of his four years as president, he stopped recruiting new students into his group, the students he had defended crap (virtually unmentored) projects. Upon completion of his four-year term, the society started a publicity campaign to get top-rated professors and industry experts to write letters of support for this professor to various federal, military and private research funding decision-makers because his lack of results from previous funding that dwindled during his presidency looked really bad on his new grants. The money started flowing in, the famous professor acted like he was still president, didn't do much to support his few students. The rest of the faculty felt bad for these students and essentially pushed them through the program with stupid projects, stupid results, stupid justifications and background stories to introduce their project in their dissertation.

Many university research projects and results are crap.

Also, there is a great site that monitors retracted papers from professional journals...
RetractionWatch.com so much crap.
https://retractionwatch.com/the-ret...rd/top-10-most-highly-cited-retracted-papers/

 

Well, when I got my PhD at a top-20 science & engineering school, there were plenty of projects that weren't quite working as planned, Since a PHD degree needs a positive result (not a failed experiment), some late 3rd year, 4th year and 5th year students start grasping at straws. They publish the little parts of the project that worked (no matter how stupid or inefficient or vacuous they may have been) because nobody has time to start a new project. The goal was to get their two reviewed publications into the literature, employers never read them, they just count them. I did a post-doc at a very prestigious school and thought things would be different - but it was the same there too. Some research results are stupid.

Do you know what they call the graduate student who barely defends their project in front of their committee? A PhD.

While there are studies and other research that is faked or shallow, you apparently didn't read the article or the linked page carefully. Your experience notwithstanding, assuming vacuity is just not sensible, instead assuming that something is there to be found, particularly when the first source is some sort of popular science reporting—which will often miss or misreport things.

Becuase I didn't assume it was an empty research program, I read further and sure enough there was something to be found.

 

Wireless power transmission is one of those subjects that becomes "hot" for a decade or so.
Every researcher and startup company jumps on the bandwagon, countless millions are invested, very little real value emerges from the effort.

At a time where energy is becoming more expensive, why are people investing in less efficient ways to to power devices?

Too lazy to plug in a cord?
Yes. Sadly that's the true answer.

 

No, they spatially distributed the laser with one has as the transmitter and the other the receiver.

I don't know what you are trying to say here, I assume any wireless system needs the transmitter to be specially separated from the receiver.

While the lede is buried in the story, it is the demonstration of a distributed laser that is the innovation. There is not claim of practicality, this is basic research in anticipation of efficiency improvements and other components.

If you are claiming the reporter missed the important part, and the researcher's innovation is really a demonstration of a "distributed laser", I am confused.

I searched the technical paper and that phrase (distributed laser) does not even come up in the paper itself (except as comparative references) and the acronym (DLC distributed laser charging) only occurs in the intro or references as well.

Here is the paper.
I just don't see any thing with merit in the results.
https://opg.optica.org/oe/fulltext.cfm?uri=oe-30-19-33767&id=497548

Here is a 4-year-old paper from a different author demonstrating a Distributed Laser Charging system from IEEE.
https://ieeexplore.ieee.org/document/8398229

Im just not seeing the merits or innovation or benefit to other researchers in this or even the IEEE paper from 2018.

 

I don't know what you are trying to say here, I assume any wireless system needs the transmitter to be specially separated from the receiver.

If you are claiming the reporter missed the important part, and the researcher's innovation is really a demonstration of a "distributed laser", I am confused.

It’s very odd that you are “confused”. The paper makes it very clear. As far as innovation there’s this:

Moreover, a novel power transmission technique for multiple receiver charging using spatially distributed laser cavity with built-in safety mechanism was introduced by Jaeyeong Lim, et al., in our laboratory.

The “spatially distributed laser cavity” refers to the resonant cavity comprising the path from the transmitter to the receiver. That is, the laser hits the target and part of the beam is returned back along the same path by a retroreflector. It is the return beam that initiates the amplified emission, so the resonant circuit is the entire path and not just the internals of the laser source.

The reflected signal from the ball lens follows the resonating path and enters the transmitter’s gain medium for amplification, thereby completing the resonance cavity and inducing a power transfer mode. If the resonance cavity is uninterrupted the power continues to transfer from the transmitter to the receiver. In the event that a foreign object interrupts the resonance path, the resonance immediately stops, and the system automatically shifts to a safe power transfer mode. In this mode, the transmitter produces an incredibly low intensity light that does not pose any risk to humans.

I have no idea what your experience with photonics or power transmission is like, but this research is not intended to result in a practical power transfer device which is very clear from the paper. The experiment was about making incremental steps in the use of a spatially distributed laser cavity for such a device. It achieved longer distances than previous experiments and showed that using the spatially distributed laser can improve safety by automatically reducing power if it is obstructed and regain the power transfer when the obstruction is gone.

I have no idea where you have the idea there was nothing novel or useful about this research. I guess you really are confused.

 

It’s very odd that you are “confused”. The paper makes it very clear. As far as innovation there’s this:



The “spatially distributed laser cavity” refers to the resonant cavity comprising the path from the transmitter to the receiver. That is, the laser hits the target and part of the beam is returned back along the same path by a retroreflector. It is the return beam that initiates the amplified emission, so the resonant circuit is the entire path and not just the internals of the laser source.



I have no idea what your experience with photonics or power transmission is like, but this research is not intended to result in a practical power transfer device which is very clear from the paper. The experiment was about making incremental steps in the use of a spatially distributed laser cavity for such a device. It achieved longer distances than previous experiments and showed that using the spatially distributed laser can improve safety by automatically reducing power if it is obstructed and regain the power transfer when the obstruction is gone.

I have no idea where you have the idea there was nothing novel or useful about this research. I guess you really are confused.

If one reads the references listed in the paper cited by the press release, it shows that the authors did not develop the specially distributed laser. The authors clearly cite another researcher's work as the first case the term was used - Spatially Distributed. The use of a spatially distributed laser in this application yields such a low amount of transferred energy that I would personally be embarrassed to publish the result as a positive experiment. Even more embarrassed that someone decided a press release is needed to promote the publication that describes a way to transfer a micro-yield of energy transfer.

My nose says this "science" smells like a physical science version of "vaporware." Im not in the mood to tell anyone else they are wrong for sensing a smell of roses after reading the article and looking into the important references - their sense of smell is not going to change my life. I believe it is just time to fund some different professor's research and cut bait on this one.

 

agreed... i see nothing novel or useful mentioned. certainly does not seem to be news worthy.

there are other experiments and demonstrations that transferred way more power over longer distances and much of this was done years ago. aiming laser at moving target is also nothing new. turning laser on/off is also nothing new. transferring power with much MUCH higher efficiency is also nothing new. the most significant part of the article was "we are doing something and one day this will be awesome" with nothing to support the claim or put it on the map of progress or compare it with alternatives...
i recall micro sterling engine powered by laser, or one where laser was aimed at the bottom of a cone, burning air and providing trust for up to few hundred feet. then there are experiments transferring meaningful amounts of power (order of kW) and efficiency (50-90%). compared to those, achievements mentioned in the article are disappointing.

 

agreed... i see nothing novel or useful mentioned. certainly does not seem to be news worthy.

What was new was using the spatially distributed laser technology in such a way that it would automatically reduce that power to a safe level if something intervened and re-establish the higher power link when it was clear. The mechanism to do that is inherent in the laser configuration.

This is what the researchers were demonstrating, not tracking, not efficiency, and not absolute power transfer. Not even "turning the laser on and off" but a method of doing that which is intrinsically safe. That is something new and important. If it can be combined with other things to make it a useful power source, it is one solution to safety concerns.