What you can't see CAN hurt you... but can be pretty useful...

As I showed in my video blog in my last post, infrared light is invisible to the naked eye.  You can detect its presence with an infrared viewer or infrared camera, but not many people carry those around with them.  My green laser pointer emits infrared light in addition to the green light.  This can be dangerous because that infrared light adds to the power of the total beam, and it makes the beam more capable of causing eye injury.  That means the user has to be extra careful to not shine the laser toward people.

Infrared light isn't all bad though.  Many high powered lasers, like CO2 or Nd:YAG lasers, use infrared light (a lot of it) to cut through materials.  For CO2 lasers and Nd:YAG lasers, the output wavelength is 1064 nm, which happens to be the same wavelength of infrared light that my green laser pointer emits.  The Nd:YAG laser is used for 3D engraving.  Check out the video below to see how that works!

What else can infrared light be used for?  Here is a project for those do-it-yourself-ers out there!

*************** AS ALWAYS, SAFETY FIRST! ***************

You can order an infrared laser* or LED (or buy a green laser pointer like mine and block only the green) and shine it toward an IR photodiode.

So what?  What does this accomplish?

Well the photodiode will sense when the laser is shining on it AND WHEN IT ISN'T!  If an object or person passes through the laser, the photodiode will know!  People won't be able to see the beam or spot on the photodiode, so the system can be used for security purposes.  Ever see laser trip alarms in movies or video games?  This is how they would work!
 
*You could get away with a cheap red laser.  Check out this link that shows the steps for the DIY project.

Many garage doors have a system like this (probably using an infrared LED) to detect whether there is an object or person under the garage door as it closes.  You have probably seen this and may have, like me, had to jump over the beam while ducking your head if you want to close the door and get out at the same time!

The secret behind green laser pointers -- VIDEO BLOG

I took a trip down to the laser lab to get the scoop on my green laser pointer.  The following video documents my journey:

The take-home message?  Just because you can't see the infrared doesn't mean it isn't there.  It can burn your eyes just as much as the green can.  Just keep that in mind if you get your hands on a cheap green laser pointer.

For your reference, here is a chart of the electromagnetic spectrum, which shows where visible light is, and where infrared light is in relation to each other.

     The three spots we saw in the video were the separated colors of light from my laser pointer.  The left spot was green (532 nm), the faint middle spot was near infrared from the pump (808 nm), and the right spot was the infrared (1064 nm) that gets frequency doubled to green.  Here is the picture in the video showing the steps taken to produce the green light:

 

     In the video, I refer to an "infrared camera," but the tool I use is actually called an infrared viewer.  The combination of the viewer with my camera, though, does imitate an infrared camera!  So my verbal mistake wasn't too far off.  Also, the video alludes to a nonlinear crystal that converts infrared light into green light.  This is a fancy way of saying that the atoms in the crystal absorb reddish-colored light and emit green-colored light.  This happens through a nonlinear process, and needs to happen because there are cheap materials that naturally can be used to make an infrared laser.  Only recently has there been success with true-green emitting materials, as I report in my 3OH!3 post.  I discussed a little about nonlinear processes in Adding and Subtracting for those who want to learn more.

Take a look, and enjoy the cool things I demonstrate in the laser lab!  And definitely ask me questions if you have any!

FOX catches on...

     It looks like a reporter at FOX News has stumbled on the story about the Navy laser project I have been posting about.  The FOX report includes some details about the Navy maritime laser demo, the free-electron laser project, and a rail gun project they are working on too.  On FOX Nation, they also show the maritime laser demo video I posted in Navy laser demo.

I actually noticed a problem in the FOX News article about the free-electron laser.  In the article, they say,

"Called the FEL -- for free-electron laser, which doesn't use a gain medium and is therefore more versatile -- it was tested in February consuming a blistering 500 kilovolts of energy, producing a supercharged electron beam that can burn through 20 feet of steel per second."

The problem is that they claim the laser produces a "supercharged electron beam" which is what burns "through 20 feet of steel per second."  If the reporter had researched free-electron lasers, he would have known that the laser does produce an electron beam, but the beam oscillates causing the emission of an intense beam of photons, or a laser beam.  It is the intense laser beam that does the burning, and not the electron beam.

     I believe this inaccurate reporting, even though it seems like a small detail, is due to the fact that the FOX reporter is most likely not a scientific journalist, and so he did not understand the science in the first place.  There is another possible reason for the misreporting; the reporter might have believed that readers would not understand the science, so he simplified the science to focus on the big picture.  However, scientific journalists are much rarer nowadays than previously, so the first hypothesis is likely the correct one.

     I am also interested in the rail gun report seen in the FOX article.  It appears the Navy does not believe the rail gun will be ready until 2025.  Yet, there have been references to rail gun technologies in older video games (Metal Gear Solid, in which the big bad machine is equipped with a rail gun) and movies (Transformers 2, in which the Navy takes down a giant machine on top of a pyramid with a shot from a rail gun).  Word gets around, I suppose.

Navy laser demo

     Remember that laser the Navy was working on?  The one that cut through ridiculous amounts of steel per second?  Well check out this video I found at geek.com.  It shows a lower powered prototype of what they are after.

The article at geek.com describes more about Star Wars efforts, the Navy laser, and the Boeing laser that I have been posting about.  Looks like someone else is interested in this stuff too!

There is also a 5 minute Navy PR video concerning the laser system in the following video, for anyone interested in the Navy laser defense systems.  The PR video explains the Navy's goals and has some nice footage of takedowns.

The Power of the Sun

     The sun is an amazing thing.  It allows us to live on this Earth by heating the planet from 93 million miles away.  The sun uses fusion to do this.  Fusion is the process by which Hydrogen atoms combine to form Helium atoms - a process that happens to release a large amount of energy.  Across the globe, there are efforts to control the immense power of fusion to supply the world with energy.  But there is a catch --- How are we supposed to even induce fusion in a controlled manner?  The H-bomb needed fission explosions to provide the heat and pressure required to induce fusion.  Won't our efforts to start a fusion reaction end in destruction if we use the H-bomb technique?

     That's where lasers come in.  Small amounts of fuel can be heated and pressurized through the use of lasers and some other structures.  There are two methods to control fusion that are being researched currently:  Inertial confinement fusion (ICF) and magnetic confinement fusion (MCF).

     ICF uses a pellet of Beryllium and isotopes of Hydrogen (the fuel) filled in a gold cylinder.  Lasers hit the outer layer causing it to explode, creating huge shockwaves, high pressure, and immense temperatures inside the cylinder.  An IOP article states that an experiment at the National Ignition Facility shot 192 laser beams at one of these cylinders to produce temperatures up to 3.6 million degrees Celsius!  That's hotter than the sun, people.

     MCF uses strong magnetic fields to create a "magnetic pressure" on the plasma of the fusion reaction.  Other methods besides using lasers are used to heat the plasma in MCF.

     Fusion is a seriously cool topic, and it is amazing how lasers can be used to produce such extreme conditions to induce fusion.  How many people can say they have mimicked the sun with their research?  Not me, but maybe someday!

Laser welding

     I knew there were tons of applications for lasers in industrial settings, but I was unaware that laser could be used to weld metals.  Cutting?  Sure.  Drilling?  Duh.  Scribing?  Of course!  Welding?  Wow.

     With all of the videos I've posted and stories I've told about lasers obliterating whatever they hit, I had no idea that the heat produced could be controlled to fuse two metals together.  A story at FEN describes how lasers can be used to weld "titanium, beryllium, copper, and platinum," materials that cannot be welded by traditional methods.  Not only that, but the narrow beam of the laser can create incredible welding precision.  The only downside is the cost, but the technology is reasonable for certain welding types and large scale production.

Another application to add to the list!

E-Days Let-Down

     The end of last month brought to all of the students at the Colorado School of Mines what they had been craving for all year.  That's right.  E-Days!  And along with it, comedians, a concert, chances to win prizes, competitions, activities galore, and, of course, the laser light show!

Wait.... Laser light show?  What about the fireworks?  No fireworks?  WHAT???

     The thing that really gives CSM students a thrill that will last them until next year, the amazing fireworks display of E-Days, WAS CANCELED!  Replacing it was a laser light show that would normally get a laser physics enthusiast excited.  But this laser show was far from phenomenal.

What made the laser light show so bad?  Here are just a few concerns I had:

1) The school was ill-equipped.  There were only four, stationary laser projectors, two of which only emitted green lasers.

2) The animations were neat at first, but it was clear that they were put together hastily.  Parts of the animations were just stationary outlines that slid across the screen, an underwhelming element of the show.

3) The music selection was terrible.  Classic rock did not mesh well with a show that inherently felt like it belonged at a rave.  People got up and danced to the single pop song that was included, but the urge to dance evaporated for the rest of the show.

4) The attempt at sex appeal was so terrible, it was less than laughable.  The producers apparently thought that poor outlines of women roller skating and doing strange dances would turn on the viewers.  I felt embarrassed just to watch it.

5) The scanning of the lasers through the fog was neat since the air currents added a dynamic experience to the effect, but the novelty of the stationary scanning soon wore off.  

6) Saying the laser show was a replacement for the fireworks would make any CSM student feel wronged.

     I'm not saying the show was that terrible.  I know a lot of effort must have been put into making the show as good as it was.  I could have done no better myself.  But there was just a feeling of monotony and awkwardness to the whole thing.  The technology was all there, but its implementation was lacking a professional touch and a fitting musical environment.

All I can pray for is some rain so that the fireworks will be allowed once again.  Then things may be right in the world once more.