Highly Directional Terahertz Laser Demonstrated

eldavojohn writes "A new paper published this week in the journal Nature Materials announces a successful demonstration of highly directional terahertz semiconductor lasers. You might not think it's a big deal that some Harvard and University of Leeds researchers (funded partially by the US Air Force) figured out how to better direct lasers; but this means the ability to see what's in someone's pockets and clothing, at a distance of possibly hundreds of meters, or farther. The big benefit is that they are lower in energy than X-Rays and are less invasive, since they cannot pass through water or metal. Coming soon to an airport near you or buzzing around on board a drone in civilian airspace?"

Comments

Plus flying cars?

[mangu]

The Wired article has a sidebar with "Featured Articles", one of them is "Flying Cars are Coming".

Does this tell anyone about how soon this laser will have real world applications?

Re:Plus flying cars?

[Foobar_]

If it's a laser pointer made with a red (670, 650, 635 nm), blue (445 nm), or violet (405 nm) laser diode, there's absolutely no infrared emitted.

If it's a properly made diode-pumped solid-state laser pointer (532 nm green, 473 nm blue, 404 nm frequency doubled violet) there's an infrared filter in the optical train which removes the large amounts of invisible pump light and leaves only the visible green.

If it's a crap green laser pointer (e.g. the "high power" green pointers sold on eBay and the like) then there is a real possibility the manufacturer omitted the IR filter to increase profits and/or the balloon-popping potential of the pointer. Check with a laser power meter and an IR-passing filter to verify the lack of IR output.

If no such tools are available, use a camera sensitive to infrared, block the visible beam with a filter, and check that no IR is coming out. IR-passing, visible-blocking filters around the house include the tinted plastic windows on remote controls and the front panels of remote-controlled devices, exposed color photo film negatives, and the disks of coated Mylar film inside floppy disks. Those last two should never be used as filters to observe the Sun due to the fact they totally pass IR and you can cook your retina in seconds without realizing anything bad is happening.

Infrared leaks may not be collimated like the green beam and will be visible (on camera) as a beam, cone, or ugly spray of light coming out of the filtered device.

http://en.wikipedia.org/wiki/Laser_pointer#Infrared_hazards_of_DPSS_laser_pointers

There are reflected light hazards to worry about with all lasers. For example, shining the laser onto a smooth or polished floor in the direction of your pet will result in some light making a dot on the floor and most of the light bouncing off into your pet's eyes. If you can see the laser's reflection light up your pet's face, you may be causing eye damage.

If it's a high-power laser pointer (output over 5 mW) you are being carelessly negligent in its operation if you're waving it around in any situation where people or animals can get hit in the eye with its beam. Safe eye exposure is probably much less for cats and dogs due to the presence of a tapetum lucidum which concentrates light hitting their retina, their much larger pupils which take in much more light, and active suppression of the blink/turn reflex due to the fact they're chasing that dot and don't want to look away from their quarry.

In related news...

[fahrbot-bot]

The big benefit is that they are lower in energy than X-Rays and are less invasive, since they cannot pass through water or metal.

...sharks disappointed.

Re:In related news...

[Surt]

Not the sharks with frickin' jetpacks.

Re:In related news...

[Shark]

There's a jetpack? I didn't get the memo...

Oh God

[CasualFriday]

So now airport security officers can see my genitals from hundreds of feet away?

Re:Oh God

[Anonymous Coward]

Wearing tinfoil underwear will be a detainable offense - you could be hiding something in there! Like your dignity, for instance.

Re:Oh God

[EdIII]

So now airport security officers can see my genitals from hundreds of feet away?

Even with that technology, I still don't think we will be able to find your genitalia. Sorry.

Re:Oh God

[Beardo the Bearded]

Dude, I'm 33 years old. I'm married and I've got two kids.

It has been years since anyone has been interested in my genitals, and I kind of miss the attention.

Re:Oh God

[CasualFriday]

This is unbelievably depressing. also, I love how there is a button at the bottom of your post that says "parent".

Re:Oh God

[ShadowRangerRIT]

Given that even water would deflect these lasers, peeing yourself should be a sufficient means of blocking them.

"Less invasive than X-rays"

[Daniel Dvorkin]

Um, no, I know when I'm being X-rayed. A remote sensing system that can see what I have in my pockets a mile away, without my knowledge, is highly invasive.

Yes, yes, they mean "invasive" in the medical sense: the frequencies they're using don't penetrate inside the body. But it would be nice if they'd clarify the meaning without being so blase about it. "DHS will be able to scan anyone, anywhere, any time for anything -- what could possibly go wrong?"

Re:"Less invasive than X-rays"

[Anonymous Coward]

I give you a hint; There is not much sunshine.

My butthole emits blinding white rays of heavenly light you insensitive clod!

so it does not work with sharks?

[Joe The Dragon]

so it does not work with sharks?

Re:so it does not work with sharks?

[Delarth799]

Not yet, but those bastards keep making the technology smaller and smaller and more powerful! One day they will make it small enough to be mounted onto a shark, and at that point someone else will have cloned raptors. The sharks and raptors will grow up together and then the world will end, taken over by raptors riding sharks with laser beams, all because science couldn't stop to think about the consequences!

Re:PSA

[Daniel Dvorkin]

The "M" in MASER stands for "microwave." The waves used here are non-visible, sure, but they're shorter than microwaves, closer to what's usually called infrared. And "laser," no longer capitalized, has entered the language as a word for any device that emits a beam of coherent EM radiation of whatever frequency -- thus you'll hear "IR laser," "X-ray laser," "gamma laser," etc. It would be pretty silly to insist on a separate word for each frequency band.

Arms race

[spleen_blender]

I will not be surprised to find soon there is an inexpensive way of shielding against this.

Then again, if you've got nothing to hide, why do you have tinfoil lined pockets, citizen?

Business opportunity!

[tomhudson]

Since it won't pass through metals, quick, someone patent the tin-foil bra!

Oops, too late, now it's in the public domain :-)

Re:Violence-minded people...

[Dunbal]

U.S. society: Violence-minded people want to spend taxpayer money for endless war.

      Oh no, this would be privately funded! :)

Bogus info from Tired

[Animats]

Tired Magazine blows it again.

The article from Tired is bogus. The "remote generation of terahertz radiation" is described in this paper. They generate terahertz radiation at the target by hitting it with a big enough pulse to heat it up into a plasma. This is a classic spectroscopy technique; hit something with a big laser pulse and look at the spectra coming back.

Nobody is going to look into pockets that way, unless they burn through first. It may be useful for analyzing toxic and hazardous materials from a distance. A possible application is something that first responders point at a spill from a distance, and it comes back with an analysis. Assuming the energy transfer can be made small enough so as not to ignite anything.

Re:Bogus info from Tired

[Surt]

So your claim is that the TSA cares enough about passenger wellfare to not plasmify their customers? I think you underestimate their devotion to providing a comfortable, pleasant travel experience.

Re:No kidding.

[Surt]

Yeah, if you have to be a scanner, definitely be a scanner for the first class passenger line.

Re:No kidding.

[Surt]

Their trophy girlfriends tend to be. I mean, there's no avoiding scanning some of the wrong sex unless you're bi, so assuming you're a horny male heterosexual screener, your odds are best with the first class passengers.

Re:wet suit.

[JSBiff]

"Time to buy . . . a full metal jacket."

Yeah, I bet having Ammo in your pockets or bags will really expedite your trip.

Co-author checking in

[Mkoms]

Hey guys, I'm one of the co-authors of that Nature Materials paper. Please let me know if you have any technical questions about the work. I'm not an expert on terahertz semiconductor lasers or their applications (I was really only involved in the surface patterning of the facet with the spoof plasmonic structures), but I'll do my best to answer any questions you might have.

Watch out for perverts.

[Mr2cents]

With all those perverts around, my advice to beautiful women is to keep your T-shirt wet at all times.

Is that a banana in your pocket or are you...

[gearsmithy]

oh wait, it is a banana