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Laser Powered Broadband? In Space? Wait. What?

Ok, there is something very interesting taking place with NASA this month.  On September 23, NASA decided to approve three projects that are being called “Technology Demonstration Projects.”  A space-based optical communication system (which is what I find the most exhilarating), a deep space atomic clock, and a big ol’ space sail.  From the NASA Office of the Chief Technologist‘s office:

NASA has selected three proposals as Technology Demonstration Missions that will transform its space communications, deep space navigation and in-space propulsion capabilities. The three Space Technology projects will develop and fly a space solar sail, a deep space atomic clock, and a space-based optical communications system. These crosscutting flight demonstrations were selected because of their potential to provide tangible, near-term products and infuse high-impact capabilities into NASA’s future space exploration and science missions. By investing in high payoff, disruptive technologies that industry does not have in-hand today, NASA matures the technologies required for its future missions while proving the capabilities and lowering the cost for other government agency and commercial space activities. 

Ok.  Personal commentary?  What a weird three projects to say “Hey, don’t take our money away, you crazy Congress people and President Obama, we’re NASA.”  I can see the space based laser communication system, that’s pretty cool.  Now granted no one asked me (and I know better that’s probably the main cause we don’t have a space-based laser that can scratch your back), but I’m sure there is reasoning behind these other two projects.  Right?

Right?

Check this out – again,. from the press release at NASA – it’s about this big space laser data communication thingie, called the  Laser Communications Relay Demonstration Mission:

Led by the NASA Goddard Space Flight Center in Greenbelt, MD, the Laser Communications Relay Demonstration (LCRD) will demonstrate and validate a reliable, capable, and cost effective optical communications technology for infusion into operational near earth and deep space systems. The Space Communications and Navigation (SCaN) office in the Human Exploration and Operations Mission Directorate is collaborating with the NASA Office of the Chief Technologist in sponsoring this technology demonstration. 

Optical communications (also known as laser communication – lasercom) is a transformative technology that will enable NASA, other government agencies and the commercial space industry to undertake future, complex space missions requiring increased data rates, or decreased mass, size, and power burdens for communications. For approximately the same mass, power, and volume, an optical communications system provides significantly higher data rates than a comparable radio frequency (RF) system. 

High-rate communications will revolutionize space science and exploration. Data rates 10-100 times more capable than current RF systems will allow greatly improved connectivity and enable a new generation of remote scientific investigations as well as provide the satellite communication’s industry with disruptive technology not available today. Space laser communications will enable missions to use bandwidth-hungry instruments, such as hyperspectral imagers, synthetic aperture radar (SAR), and other instruments with high definition in spectral, spatial, or temporal modes. Laser communication will also make it possible to establish a “virtual presence” at a remote planet or other solar system body, enabling the high-rate communications required by future explorers. 

As an example, at the current limit of 6 Mbps for the Mars Reconnaissance Orbiter (MRO), it takes approximately 90 minutes to transmit a single HiRISE high resolution image back to earth. In some instances, this bottleneck can limit science return. An equivalent MRO mission outfitted with an optical communications transmitter would have a capacity to transmit data back to earth at 100 Mbps or more, reducing the single image transmission time to on order of 5 minutes. 

The LCRD mission will:

  • Enable reliable, capable, and cost effective optical communications technologies for near earth applications and provide the next steps required toward optical communications for deep space missions
  • Demonstrate high data rate optical communications technology necessary for:
    • Near-Earth spacecraft (bi-directional links supporting hundreds of Mbps to Gbps)
    • Deep Space missions (tens to hundreds of Mbps from distances such as Mars and Jupiter)
  • Develop, validate and characterize operational models for practical optical communications
  • Identify and develop requirements and standards for future operational optical communication systems
  • Establish a strong partnership with multiple government agencies to facilitate crosscutting infusion of optical communications technologies
  • Develop the industrial base and transfer technology for future space optical communications systems

Ok, now that does sound pretty cool.

How do you feel about these projects?  Worth the money?  NOT worth the money?  Leave a comment below!

Crazy Friday Science: Mini-Interview with Sonja Franke-Arnold on Rotary Photon Drag

I wrote an article about a paper I read in the journal Science a few weeks ago – the article was about Rotary Photon Drag Enhanced by A Slow Light Medium.  I got two handfuls of emails about the article, so I got in contact with one of the original paper’s editors, Sonja Franke-Arnold.  When you have questions, it’s best to go to the source!

JimOnLight.com:  Hi Sonja, welcome to JimOnLight.com! I’m very interested in your research, and we’ve gotten a lot of interesting response to the post I wrote on your paper, “Rotary Photon Drag Enhanced by a Slow-Light Medium.”  Can you take a moment and give us a bare-bones layperson’s look at what you and your team has discovered? What exactly has happened here in your experiment?

Sonja Franke-Arnold:  We were wondering how the world looks like through a spinning window!  About 200 years ago Augustin-Jean Fresnel predicted that light can be dragged if it travels through a moving medium. If you were to spin a window faster and faster, the image would actually be slightly rotated as the light is dragged along with the window. However, this effect is normally only some millionth of a degree and imperceptible to the eye.

We managed to increase the image rotation by a factor of about a million to an easily noticeable rotation of up to 5 degrees. This happened by slowing the light down to roughly the speed of sound during its passage through the “window” (in fact a ruby crystal). The light therefore spent a longer time in the ruby rod and could be dragged far enough to result in an observable image rotation.

JimOnLight.com:  Can you explain the significance of the wavelength of light you used? Why was 532nm (green) used for the experiment?

Sonja Franke-Arnold:  This wavelength excites a transition within the ruby crystal (the same that is also used in ruby lasers). Light at 532nm is absorbed and excites an atomic level with a very long (20 millisecond) lifetime. This allows to “store” the energy of the photon as an internal excitation of the rotating ruby crystal – generating slow light.

JimOnLight.com:  Tell me about the significance of the shape of the coherent beam in the experiment – was the shaped beam simply to observe a change in the image, or was a different purpose considered?

Sonja Franke-Arnold:  We used an elliptical light beam for two reasons, one of these is to define the image rotation angle as you suggested. The elliptical beam travelling through the spinning ruby rod however also plays an important part in making the slow light itself: At any particular position of the ruby, the elliptical light – spinning with respect to the ruby – looks like an intensity modulation. The varying intensity produces a large refractive index of about one million which slows the light down from the speed of light to roughly the speed of sound – a method pioneered by our co-worker Robert Boyd.

JimOnLight.com:  Could you give a few examples of uses for this discovery? How can the general populous relate to what this discovery really means for light and photonics?

Sonja Franke-Arnold:  For me, the main highlight was that we managed to observe a 200 year old puzzle – that images are indeed dragged along with rotating windows. We are now working on possible applications in quantum information processing: our image rotation preserves not only the intensity but also the phase of the light and could therefore be used to store and rotate quantum images. Access to the angle of an image could allow a new form of image coding protocol.

Thanks so much, Sonja!  Very cool paper for those of us nerds out here!

Rotary Photon Drag Enhanced by a Slow-Light Medium. Right? Right.

Remember that scene in the Jody Foster movie called Contact when they got all of those drawings of “the machine?”  There was a part of the movie where Ellie realized that the images were encoded somehow, and the key to encoding them was by looking at them in three dimensions.  Remember that minute little detail?

I read an article on this just the other day, and after I read the entire article in the journal Science, I really want to share the gist of this thing with you all.  It totally reminds me of this for some reason.  I was explaining this all to a friend on Skype, and I got tired of typing, and then the researcher slice of my brain started going ape-sh**.  Pardon me.

First, read the abstract of the article written by Sonja Franke-Arnold (School of Physics and Astronomy (SUPA), University of Glasgow, Scotland), Graham Gibson and Robert W. Boyd (Department of Physics, University of Ottawa, Ottawa, Canada), and Miles J. Padgett (The Institute of Optics and Department of Physics and Astronomy, University of Rochester, Rochester, NY):

Transmission through a spinning window slightly rotates the polarization of the light, typically by a microradian. It has been predicted that the same mechanism should also rotate an image. Because this rotary photon drag has a contribution that is inversely proportional to the group velocity, the image rotation is expected to increase in a slow-light medium. Using a ruby window under conditions for coherent population oscillations, we induced an effective group index of about 1 million. The resulting rotation angle was large enough to be observed by the eye. This result shows that rotary photon drag applies to images as well as polarization. The possibility of switching between different rotation states may offer new opportunities for controlled image coding.

Ok, got it?  Yeah, read it a few times, but generally the concept of the experiment is pretty simple, and the results are very interesting!  What these folks were doing was shining a shaped, collimated beam of light through a spinning ruby disk rotating at a given speed – in this case a maximum of 30 cycles per second.  The ruby disk causes a bit of “drag” on the photons travelling through it, causing the light to refract and exhibit some interesting behavior.  Check out this little video, from the paper and from the journal Science:

to view the .MOV file, click here

Ruby has a heavy Index of Refraction, which means the light is slowed down (refracted) at a rate of X when it leaves the air and enters the ruby itself.  If you imagine the 1.0 value of the Index of Refraction as how light travels through regular ol’ air (and not taking into account humidity, pollution, or any of that schtuff), anything greater than 1.0 is refracting.  Diamond has an Index of Refraction of about 2.42, and Ruby’s Index of Refraction is about 1.77.  Ruby refracts less than diamond.  Make sense if you didn’t already get it?

Here’s the weird thing – Ruby is not what we consider isotropic – meaning that no matter what the incidence angle is and no matter what the orientation of the crystal is, the light travels through the crystalline matrix equally as it travels through the medium.  Glass, sodium chloride crystals, and a lot of polymers exhibit this kind of “perfect” structure.  Sodium chloride is basically a cubic structure, relatively perfectly bonded in a cube matrix.  Ruby, on the other hand, is an anisotropic crystalline structure, meaning that there are more than one axes that are different within the structure of the crystal matrix.

Here’s a good image of the difference between an isotropic and anisotropic crystal structure, optically, from Olympus America’s Microscopy Resource Center.  Figure A is a sodium chloride crystal, which is isotropic.  Figure B is a calcite crystal, which has calcium ions and carbonate ions in it.  Calcite is anisotropic.  Check it:

Ok – now if you think of a crystal structure with light shining through its matrix, and the light is going to pass through two different planes of refraction, essentially – what do you expect to happen to one beam of light as it enters the anisotropic crystal structure and slows down?

Who said it’s going to split into two beams?  (DJ Lemma, pout your hand down, I know you already know the answer!)  You’d be correct – the incident beam splits into two beams, each sort-of along that individual crystal plane.  Take a look at this image of a calcium carbonate crystal, and how it is creating a double image:

This phenomenon is called birefringence.  Deep breath – bi-re-frin-gence.  Ruby, the gem used in the experiment, is also an anisotropic crystal, and it exhibits traits of birefringence.

So, imagine taking that birefringent crystal disk, spinning it at a relatively high rate (30 Hz), and shining a very specific wavelength of light (ie, a laser), that is in a certain shape through the ruby disk as it spins.  A bunch of stuff was discovered with this experiment, all related to the image.  The generalities of the experiment, as I paraphrase, is that the group shone a very bright laser with a square-ish shape through the ruby disk, noted the position that the laser had ont he other side of the ruby disk after it was on the other side of the disk.  When you shine a shaped laser beam at 532 nanometers (green) through a spinning ruby disk (which is a very slow-light medium, slowing the light down to just a few tens of meters per second) spinning at a rate between not spinning and 30 rotations per second, the image refracts from about a third of a degree to about ten degrees as the ruby disk increases from slow revolutions per second to thirty revs per second.

What a crazy experiment, huh?  I needed a good dose of photonics and optics in my Thursday!

The ramifications of this experiment have to do with encoding images with extra data – if you can imagine an image that has more information in it depending on which way the image is spinning, that is some trippy Minority Report shizzyhizzle.  “Oh, you’ve stolen my image!  But since you don’t know which wavelength to use and at which speed to spin the image, you’ll never decode my super secret plans of world domination!!!

Yeah, I have a vivid imagination.

HUGE number of thanks:
the journal Science
PhysOrg
PhysicsWorld
the Index of Refraction of Ruby and Sapphire (actually a very cool fact doc, check it out!)

We Can’t Contain Our Big Killer Lasers

YAL-1

In a bit of irony in the world, an article was published recently stating that laser weaponry research has begun to see a bit of stalling out.  Weapons scientists haven’t been able to deal with waste heat generated by these mega lasers, and the mirrors and optics needed to focus the lasers onto moving targets can’t handle the power.  From the article at New Scientist:

In recent tests, several prototypes have suffered serious damage to their optics at intensities well below the expected levels of tolerance. “Optical damage has been quietly alarming upper management in most major programmes,” Sean Ross of the US Air Force Research Laboratory in New Mexico told a meeting of the Directed Energy Professional Society in Newton, Massachusetts, last week. There are also big problems managing the waste heat generated by high-intensity beams.

In addition to this optics and reflecting problem, heat is also slowing the progress considerably. For every watt of laser fury we develop, four watts of waste heat is generated. Scientists are having a hard time developing a low form factor cooling mechanism that might slow the laser weapons from eating themselves.

Remember the YAL-1?  The “Flying Light Saber?”  The jumbo jet with a mega chemical laser mounted inside is also experiencing some stalling issues.  Again, from the New Scientist article:

Earlier this year in the US, engineers halted tests of the $4.3 billion megawatt-class Airborne Laser short of full power to avoid damaging “a handful of optics in the turret”, according to Mike Rinn, a Boeing vice-president who manages the programme. They realised that the optics, designed years ago, would be “frail” in the presence of any contamination, which would be virtually inevitable in flight. In the next week or so, Boeing engineers will install replacement optics and test them on the ground before running the laser at full power in flight.

Do you think that this should be a signal to focus some laser research in other areas, for example, healing people?  I am very critical of energy weapons, I realize – don’t get me wrong, if we have to have mega death killer weapons, I’d much rather the research be in high energy or light-related weaponry than I would them be nuclear, chemical, or biologically based.  But instead of using such amazing technology to wipe out life, why not at least, in conjunction with annihilating each other, that we research killing cancer and other worldwide nasties, too.

I cannot for the life of me figure out why we’re not researching helpful uses of high energy technology as much as we are killer weapons.  Anyone got an answer for that?

Amyloidosis Gets Illuminated By X-Rays

Any Dr. House fans out there?  I am totally raising my hand.

If you watch the medical shows, you might hear Dr. House or Foreman say something about Amyloidosis, Lupus, or Sarcoidosis.  Someone inevitably says “it’s not lupus,” and House makes a smarmy comment about always being right.  That first condition, Amyloidosis, just got some press that I thought was pretty interesting.

Amyloidosis is  a weird unexpected buildup of the amyloid beta protein in organs of the body; it causes all kinds of really bad conditions, some of which are not well understood.  Amyloid beta protein plaque buildup is known for being present in Alzheimer Disease patients, and can affect the heart, nervous system, GI tract, liver, kidneys, and is a very nasty little monkey.  The protein builds up and just causes the organ to fail.  Unfortunately there is no cure yet, but medicines improve someone’s quality of life, from what I have been reading.

The search for a cure is ongoing, and after two paragraphs of rambling I am finally going to get to the story!  Scientists have had some success with using very high powered x-ray beams to image the amyloid beta plaques; this is a very difficult task for any imaging technology because of the amyloid size – around one millionth of a meter.  In a press release from Brookhaven National Lab, where the big Synchrotron light source lives and where the testing took place, the process is discussed:

“These plaques are very difficult to see, no matter how you try to image them,” said Dean Connor, a former postdoctoral researcher at Brookhaven Lab now working for the University of North Carolina. “Certain methods can visualize the plaque load, or overall number of plaques, which plays a role in clinical assessment and analysis of drug efficacy. But these methods cannot provide the resolution needed to show us the properties of individual Aß plaques.”

A technique developed at Brookhaven, called diffraction-enhanced imaging (DEI), might provide the extra imaging power researchers crave. DEI, which makes use of extremely bright beams of x-rays available at synchrotron sources such as Brookhaven’s National Synchrotron Light Source, is used to visualize not only bone, but also soft tissue in a way that is not possible using standard x-rays. In contrast to conventional sources, synchrotron x-ray beams are thousands of times more intense and extremely concentrated into a narrow beam. The result is typically a lower x-ray dose with a higher image quality.

Also, on how the beam works:

To make a diffraction-enhanced image, x-rays from the synchrotron are first tuned to one wavelength before being beamed at an anatomical structure or slide. As the monochromatic (single wavelength) beam passes through the tissue, the x-rays scatter and refract, or bend, at different angles depending on the characteristics of the tissue. The subtle scattering and refraction are detected by what is called an analyzer crystal, which diffracts, or changes the intensity, of the x-rays by different amounts according to their scattering angles.

The diffracted beam is passed onto a radiographic plate or digital recorder, which documents the differences in intensity to show the interior structural details.

Finding out how to see this amyloid plaque buildup is a very useful tool in tracking Alzheimer’s in patients because if we know what to look for, we can possibly see into the future a little in testing and make predictions that could save lives.  Testing has been done on mice, but the procedure still delivers too high a radiation dose for human testing.  Part of the process towards using the technique clinically is to lower that dosage, obviously.

amyloid plaque buildup

Thanks, BNL and Medgadget!

Bacteria Can Grow Wires to Communicate?! RUN!

Don’t worry, it’s not like Night of the Replicating Bacteria By Means of Nucleic Fax Transmission or anything – at least not yet.  Scientists have discovered that certain bacteria are capable of creating nanowires to communicate with each other in little nano-networks.  People have suggested that they look similar to neural networks, and we’ve discovered that most, if not all bacteria, develop these wires.

From the abstract of the publication:

Shewanella oneidensis MR-1 produced electrically conductive pilus-like appendages called bacterial nanowires in direct response to electron-acceptor limitation. Mutants deficient in genes for c-type decaheme cytochromes MtrC and OmcA, and those that lacked a functional Type II secretion pathway displayed nanowires that were poorly conductive. These mutants were also deficient in their ability to reduce hydrous ferric oxide and in their ability to generate current in a microbial fuel cell. Nanowires produced by the oxygenic phototrophic cyanobacterium Synechocystis PCC6803 and the thermophilic, fermentative bacterium Pelotomaculum thermopropionicum reveal that electrically conductive appendages are not exclusive to dissimilatory metal-reducing bacteria and may, in fact, represent a common bacterial strategy for efficient electron transfer and energy distribution.

What can this lead us to discover?  Are we looking at something that could lead the way into new ways of understanding and fighting cancer?  Perhaps a new approach to fighting HIV and AIDS?  Maybe this will lead to making the best strawberry yogurt known to man – who knows.  We’re still way early in the learning process with these nanowires, but I have to believe that we’re in for some interesting and exciting news.  Hopefully our country will look into this discovery as a means of furthering our understanding of the improvement of human life and not the creation of some kind of super weapon that turns people into piles of cherry Jello.

Check out the article in Wired’s “From the Fields” series, and thanks to The Daily Galaxy!

bacteria nanowires

Light Activation Treatment for Parkinson’s Disease

gcamp

A team of optogeneticists in California have discovered a technique that activates brain cells with flashes of light.  Using these photoreactive proteins called channelrhodopsins, scientists are able to “turn on” these proteins, and deactivate them with another color of light.  In this case, blue light turned the channelrhodopsins on, and yellow turned it off.  From the article:

The team, led by Karl Deisseroth, a psychiatrist at Stanford University, discovered that inserting channel rhodopsins into neurons allowed them to be activated by blue light. An engineered protein known as halo-rhodopsin can then be used to silence neurons by being exposed to yellow light. In the process of their research, the team also discovered a group of cells that may be responsible for the positive results of the fledgling treatment. By targeting these neurons specifically, scientists may soon have a much more effective and much less invasive method of treating Parkinson’s.

Octomom what?  Channel who?  Optogenetics is the study of using light-sensitive proteins to activate parts of the brain.  The channelrhodopsins are the light activated proteins.  It’s possible that research in this field could lead to more effective and less invasive Parkinson’s patients.

Ah, How The E. Coli Glows Under UV Light

fluorescing-bacteria

On the medical side of light for a change – up in Houghton, Michigan, scientists at Michigan Technical University have developed a way to make the E. coli bacteria glow like little indigo lightbulbs under ultraviolet light.  Apparently the E. coli bacteria really likes the sugar mannose, and just can’t get enough.  Scientists at MTU added some manose molecules to a specially-engineered fluorescent polymer, and then mixed it into some water where E. coli was having a party.  The little cilia on the E. coli bacteria hooked onto the mannose like a used dryer sheet in the winter in Colorado (that’s a static electricity joke) and coated the bacteria with the fluorescing polymer.  BAM – glowing E. coli.

This technology is

Scientists at Michigan Technological University developed a method to make the E. coli bacteria glow under UV light. The researchers believe that the technique of attaching a mannose sugar molecule selectively to pathogens can lead to a clinical method of pinpointing bacterial and maybe even tumor clusters.

From the Michigan Tech press release:

The researchers’ trick takes advantage of E. coli’s affinity for the sugar mannose. Liu’s team attached mannose molecules to specially engineered fluorescent polymers and stirred them into a container of water swimming with E. coli. Microscopic hairs on the bacteria, called pili, hooked onto the mannose molecules like Velcro, effectively coating the bacteria with the polymers.Then the researchers shined white light onto E. coli colonies growing in the solution. The bugs lit up like blue fireflies. “They became very colorful and easy to see under a microscope,” said Liu.

The technique could be adapted to identify a wide array of pathogens by mixing and matching from a library of different sugars and polymers that fluoresce different colors under different frequencies of light. If blue means E. coli, fuchsia could one day mean influenza.

With funding from a Small Business Innovation Research grant from the National Institutes of Health, Liu is adapting the technique to combat breast cancer. Instead of mannose, he plans to link the fluorescent polymers to a peptide that homes in on cancer cells.

Once introduced to the vascular system, the polymers would travel through the body and stick to tumor cells. Then, illuminated by a type of infrared light that shines through human tissue, the polymers would glow, providing a beacon to pinpoint the location of the malignant cells.

If you’re so inclined, check out the abstract here.

ecoli

Thanks, MedGadget!

RPI Creates the Darkest Material On Earth

I came across an article recently written by the Rensselaer Polytechnic Institute that discusses a discovery made by RPI – a material made from a loosely populated coating of carbon nanotubes that has a reflectance of 0.045. This is ground breaking – the current standard is 1.4%. Researchers have developed this material coating to facilitate better solar energy absorption, and this is a great thing considering that we need to develop some new technologies to overcome our addiction to oil. From the article:

“It is a fascinating technology, and this discovery will allow us to increase the absorption efficiency of light as well as the overall radiation-to-electricity efficiency of solar energy conservation,” said Shawn-Yu Lin, professor of physics at Rensselaer and a member of the university’s Future Chips Constellation, who led the research project. “The key to this discovery was finding how to create a long, extremely porous vertically aligned carbon nanotube array with certain surface randomness, therefore minimizing reflection and maximizing absorption simultaneously.”

This is an excellent discovery on many levels. Outside of the uses for Solar Power Generation and increasing the amount of sunlight we can harness and utilize, a designer like myself has to consider the usage of such a material in the entertainment lighting arena as well – a material that reflects nearly no light almost makes lighting designers’ jokes about a “light sponge” for those spots on the stage or production where you don’t want light a reality. Imagine whole soft goods made of a coating of this material. Imagine scenic paint composed of this material. The possibilities are endless.

Check out the rest of RPI’s article here.