Star Wars 3d Holograms 'close to Reality'

But while they could send a 3D hologram down the line, it took minutes to update – making lifelike movement impossible.

Now a team led by Professor Nasser Peyghambarian, of Arizona University, have developed a way of updating the image every two seconds – making it close to "real time".

The ability to beam a moving hologram to anywhere in the world could lead to holographic teleconferences, 3D adverts, and a wealth of telemedicine, engineering and entertainment industry applications.

Prof Peyghambarian said: "Holographic telepresence means we can record a three-dimensional image in one location and show it in another location, in real time, anywhere in the world.

"This advance brings us a step closer to the ultimate goal of realistic holographic telepresence with high-resolution, full-colour, human-size, 3D images that can be sent at video refresh rates from one part of the world to the other."

Harry Potter-style 'invisibility cloak' designed by scientists

At the heart of the system is a laser that burns an image on a screen every two seconds, making it the first to achieve a speed that can be described as "quasi-real-time" by Dr Pierre-Alexandre Blanche, co-author.

Dr Peyghambarian and colleagues had previously demonstrated a refreshable polymer display system, but it could refresh images only once every four minutes.

The new system can refresh images every two seconds – more than one hundred times faster – thanks to a material called a photorefractive polymer.

The images it can capture are almost as sharp as those broadcast on US television – opening up many more possible uses.

Holographs are created by mixing reflected laser light with a second laser beam to lay down a static image – typically a lengthy, complicated and delicate process.

But the ability to quickly refresh images could mean surgeons using holographs as a guide during operations or as a better way for pharmaceutical researchers to study molecular interactions for new drugs during simulations.

Two-dimensional images are taken at multiple angles in one location and sent elsewhere using computer network Ethernet and then printed with the hologram set-up.

Using a single-laser system for writing the images onto the photorefractive polymer, the researchers, can display visuals in colour.

While the current refresh rate for multicolour display is even slower than for monochromatic images the development suggests a true 3D, multicolour system may be feasible.

Lynn Preston, director of the National Science Foundation Engineering Research Centres programme in the US, said: "This breakthrough opens new opportunities for optics as a means to transport images in real time.

"Such a system can have an important impact on telepresence, telemedicine, engineering design and manufacturing and other applications. This is an early and tremendously important outcome from this three-year old centre."

The research was published in Nature.

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Can Young's Double-slit Experiment Be Performed with Laser Light?
Obviously yes!! Laser light is most suitable for the experiment.In the basic version of this experiment, a coherent light source,such as a laser beam, illuminates a plate pierced by two parallel slits, and the light passing through the slits is observed on a screen behind the plate.The wave nature of light causes the light waves passing through the two slits to interfere, producing bright and dark bands on the screen - a result that would not be expected if light consisted of classical particles. If anyhow using LASER light you are unable to see the interference pattern, it simply means some mistake is being done by you.I just love this topic!!Cheers!!1. After trying to set something alight with a magnifine glass I was looking at the circle of light...?Were you trying to start a fire with a magnifying glass? Not exactly a smart thing to do. The purple dot is probably an after image from the bright circle of light you were staring at. It should go away in less than an hour. Put a cold compress over your eyes and rest for about 20 minutes. You should be fine. If its not gone by tomorrow, make an appointment with an eye specialist. It is not bad to see the magnifying glass reflecting light and shining, it is bad to use it to start a fire.2. If we travel in slow motion, time slows down for us. What is the speed of light when time slows down?Light only travels at one speed, the speed of light in vacuum at exactly 299792458 m/s. I do not really know what you mean about travelling in slow motion unless you are referring to being near a black hole? If this is what you mean the fact is that light still travels the same speed near a black hole but its rate of progress is slowed down by the effect of the intense gravitational pull, this does not slow the light speed itself but makes the light kind of spiral so that it's progress is affected but not it's actual speed3. Is it possible for scientists to view objects light years away in real-time?Light, electromagnetic radiation, a photon travels about 5.879 10^12 miles/year.Currently all communication is a form of the speed of light.There is a way, I am fairly sure and can even discuss it at different times but it's planned in a procrastination type of way. So each galaxy is looking into the past, viewing the past, if a planet in a galaxy is 4 light years away, we both see each other presently, four years ago!There might be a way to connect distances with the same actions, something fairly easy but it does take the time for setting up the connection, to be the speed of light. I claim, I think I do understood all three.So in a way, I am saying there is a way to communicate over distance without time delay, instantaneous. And before the current thought people tell be that nothing is faster than the apes of light so that is impossible, I would have to agree that nothing is faster than light speed but I would also have to bite my tongue and politely remind them that instantaneous has no forward speed, otherwise it would not be instantaneous!Its a different process that YOU did not create, I saw it as a result of asking why does rhe universe work and I started with time dilation.4. What exactly would a hairdresser do to take dark brown hair to light brown?It depends on the hairdresser; each has their own education & training. Coloring hair from dark to light has possibilities & probabilities of it's own. When you lighten hair, you are removing the pigment of the natural color, the tonal value is what is left. That residual pigment must be corrected to the desired shade of light brown. If the colorist knows that the client does not like warm tones, they adjust formula to counteract the warmth by using cooler tones. This is true if the client has virgin (never have been colored hair) hair. If the client has been previously colored hair, this changes all the directives because now the stylist is correcting the color
2021 07 25
Saving 140 Cats and Stealing Christmas Lights | Cheers and Jeers
Every Saturday, the South Jersey Times cheers those who make our area a better place in which to live and jeers those whose actions merit derision.CHEERS: To an outstanding effort to find homes for more than 140 cats rescued from a hoarder in Pitman. After authorities descended on the apartment Dec. 17, work began to screen the animals and find them homes. While many have been distributed to various shelters and rescue organizations, more than 40 remained at Gloucester County Animal Shelter as of this week. Using social media and other forms of publicity, the shelter staff and its supporters are trying everything to find responsible owners for these critters. They've even dropped the price for adopting one of them to $25. To learn more, check out theGloucester County Animal Shelter on Facebookor call856-881-2828 and press 1 for adoptions. The shelter has been the subject of plenty of criticism in recent weeks, but the effort to resolve this hoarding crisis is worthy of recognition.JEERS: To punks trying to mar the holiday seasonin Gloucester County. We've had several reports locally of packages being stolen from porches -- that's called porch pirating now -- and Christmas decorations being stolen or vandalized in Mantua and Deptford, among other towns. A popular theft target this year are those laser light displays that pockmark your house with brilliant green dots. Even worse, vandals struck at two Glassboro churches just before Christmas. That should outrage everyone. Sadly, these issues are nothing new at the holidays, but we seem to be hearing more reports this time around. Mantua Police also posted a warning on Facebook reminding residents not to place empty boxes for valuable items in plain view when they put out their trash. It's one more signal to thieves that you have something worth taking. Keep an eye on your property and notify the police is you see trouble in your neighborhood.CHEERS to a fitting tribute. Camden County Police Department (CCPD) K-9 "Zero" held New Jersey's record for the most criminal apprehensions in the state. When his handler, Lt. Zsakhiem James found the semi-retired dog dead early Tuesday morning, the visibly somber officer decided to honor man's best friend by telling members of the media all about their adventures in the field at and home. With 68 bad guys to his credit, Zero crossed that "Rainbow Bridge" and hopefully his favorite meal -- 20 chicken McNuggets -- was waiting on the other end.JEERS to ambulance chasers. With court proceedings still under way, Cooper University Hospital will take over advanced life support services for the City of Camden thanks to legislation signed by Gov. Chris Christie in July. Problem is, ALS services in Camden have been handled by Virtua Health for the past 38 years and the organization is challenging both the legislation and a county-commissioned report they claim is inaccurate. Should a city's ALS calls be handled by the location's level one trauma center Yes. Was this legislation truly penned with the best interest of the residents of Camden City in mind We'll hold our breath.If you know of someone or something you would like to nominate for a cheer or a jeer, please send the information
2021 07 22
As much as I would've loved to take in the Bryan Adams show last night at the Brandt Centre, I had a family commitment that kept me from the show - my son Styles graduated from St. Jerome.Fortunately for me, Christopher Tessmer was able to fill in and he did a great job with the review. Check it out:Despite the logistical nightmares associated with finding parking for a sold out arena with a Brandt Centre parking lot full of farm machinery and implements, Thursday's Bryan Adams' show started without a hitch.Walking on to the huge stage with his band, it was striking to see the lack of intro video or cheesy intro music associated with most arena shows. Instead the 52-year-old singer/songwriter simply took his place in the middle of the stage to the thunderous cheers of the sold out crowd.Those looking for pyrotechnics and a laser light show would have been initially disappointed, as the vast stage was bare other than amps and instruments. The lone extravagance was the gigantic screen that centred two smaller side screens as the Canadian rock legend played the opening chords to his 1991 hit House Arrest.Sounding impeccable, Adams moved on to his No. 1 hit Somebody with nary a word to the audience. The crowd showed its enthusiasm, as half the seated audience remained standing, dancing in their seats, aisles, and anywhere else there was room to move.Pitch perfect the whole night; it's hard to recall another concert in the arena where any vocalist sounded so crisp and studio perfect.Adams made the first of a few sparse comments as the prolonged cheers died down from the second song, stating, "I don't know what you're expecting out of tonight, but all I can tell you it's kind of a long show." The allusion to his large anthology of hits elicited a roar from the masses.Another quip from the part-time European - he has homes in London and Paris - made note of the Farm Progress Show that had encapsulated much of the arena's surroundings. With an earnest tone, Adams shared, "When we arrived I noticed that there was a big farm machinery sale going on. I went out to go look around and was looking at a silo and this guy came up to me and tried to sell me one."Besides the rocker's unexpected sense of humour, there were a number of moments throughout the show that left a mighty impression on the sold out throng. During Rescue Me, Adams moved into the stands during the instrumental ending as fans took MySpace-style photos with him and mauled him with adoration. Singalongs were commonplace for the duration of the show but during Cuts Like a Knife the participation was goosebump inducing.The band, featuring the amazing Keith Scott on lead guitar, Mickey Currie (drums), Gary Breit (keyboards/piano), and Norm Fisher (bass), thrilled the arena with their unyielding melodies. Their highlight was during a medley of If You Wanna Leave Me/Touch Me where the band, save Breit, played along with Adams on white plastic pails and a black garbage can. Currie then proceeded to play a "drum" solo using the pails and various pots and pans to the delight of the audience.One lucky fan, Sierra from Moose Jaw, was invited to join Adams onstage for the Mel C collaboration When You're Gone. As Sierra joked that her mom was going to be upset, as she had said on the way there that she wanted to sing along with him, Adams joked "It's okay ... she can live vicariously through you." Dressed in short shorts and an Adams T-shirt, the attractive young woman lived up to her earlier admission that she wasn't a strong singer, yet brought many a smile as she visibly loved every second and beamed with joy.Despite briefly teasing the crowd that Tina Turner was there to perform their duet It's Only Love, and slightly pandering to audience by replacing "Alberta" with "Regina" on Alberta Bound, Adams had the audience in the palm of his hand the whole night.It was unclear if Adams failed to leave the stage during a prolonged ovation before returning for the encore, or if he simply failed to have one but one would be hard-pressed to find anyone who left unsatisfied. Between an acoustic version of Straight From The Heart and a sea of cellphones being waved around the Brandt Centre during the finale All For Love, it's nearly impossible to top the rocker's show.Although Adams has now been a part of Canada's musical landscape for 35 years it would be a mistake to label the singer/songwriter a nostalgia act. Like a fine wine, Adams has simply got better with age demonstrated by what will likely go down as Regina's best concert experience in 2012.Set list1. House Arrest2. Somebody3. Here I Am4. Kids Wanna Rock5. Can't Stop This Thing We Started6. Thought I'd Died and Gone to Heaven7. This Time8. I'm Ready9. Hearts on Fire10. Rescue Me11. 18 'til I Die12. Back To You13. Summer of '6914. If You Wanna Leave Me/Touch Me/Drum Solo15. (Everything I Do) I Do it For You16. Cuts Like a Knife17. When You're Gone18. Heaven19. Please Forgive Me20. It's Only Love21. Cloud Number Nine22. The Only Thing That Looks Good On Me Is You23. Run To You24. Straight From The Heart25. Alberta Bound26. All For Love
2021 07 19
The Hindu : Human Surgery Using Free Electron Laser
LASER LIGHT with a precise wavelength of 6.45 microns has an invisible kind of magic. It can slice through soft tissue with less collateral damage than the sharpest steel scalpel.Its special qualities were discovered five years ago by researchers at Vanderbilt University's free-electron laser center. Scientists still don't know exactly why infrared light of this specific wavelength works so well, but it got its first clinical test recently.Under the expert guidance of Michael Copeland, a former Vanderbilt neurosurgeon, a beam of infrared light tuned precisely at 6.45 microns (6.45 thousandths of a millimeter) successfully removed a sugar cube sized amount of tissue from the center of a golf-ball-sized tumor in the brain of a patient. The operation was carried out recently at Vanderbilt's W. M. Keck Foundation Free-Electron Laser Center.It is the first time that a free-electron laser (FEL), a powerful type of laser adopted by the Defense Department as part of the "Star Wars" missile defense program, has been used in a clinical operation (FEL technology was first developed at Stanford University by John Madey, who now heads an FEL program at the University of Hawai).The operation shows that the FEL is an exceptional tool for exploring never-before-examined territories in surgery,'' said David Ernst, professor of physics and interim director of the Vanderbilt center. It is the only facility in the world that produces beams of infrared laser light powerful enough to use for surgery and is equipped to perform human operations.Conventional lasers have been used in some forms of surgery for nearly three decades, but their use in neurosurgery has been limited due to the likelihood that they will damage areas surrounding the diseased tissue. But an FEL creates laser light in a much different fashion, giving an FEL beam special characteristics that allow it to cut a variety of tissues with exceptional cleanliness.Ordinary lasers generate light in either a solid (as in ruby lasers) or a gas (carbon dioxide lasers). The FEL, however, works by passing a stream of electrons traveling at nearly the speed of light through a wiggler, a device that produces alternating magnetic fields. These fields cause the electrons to "vibrate" at a specific frequency, which stimulates them to emit a beam of laser light. By varying the energy in the electron beam, an FEL can be tuned to a wide range of frequencies. The design is also capable of generating extremely powerful beams of coherent infrared light.Many scientists realized that FEL technology was an important new tool for a wide range of basic research, including biomedical applications. Initial efforts to use the FEL beam as a surgical scalpel centred on a shorter wavelength near 3 microns, but they were a failure. The researchers picked the wavelength because it was one that is absorbed readily by water molecules. But it worked too well, creating microscopic steam explosions and excessive heat that damaged surrounding tissue.In 1993 Vanderbilt biophysicist Glenn Edwards got the idea of trying wavelengths around 6.4 microns, a wavelength absorbed both by water and many protein molecules. Many colleagues didn't think the idea had much merit, but Edwards persisted. It seemed more relevant to focus on the absorption of laser light by the proteins in soft tissue rather than water,'' he said.After making some basic measurements and doing some back-of-the- envelope calculations, Edwards and Vanderbilt ophthalmologist Regan Logan tried the beam on some corneal tissue. It drilled a perfect hole. We looked at it in disbelief. I have never had an experiment work the first time,''he said.Edwards and Logan invited a number of other scientists to test the technique, including Michael Copeland. They conducted a number of experiments on a variety of tissues and found that wavelengths near 6.45 microns were optimal for cutting all soft tissues. They published these results in Nature in 1994.Since then other researchers have found two wavelengths - 7.5 and 7.7 microns - that cut through bone particularly cleanly. Despite the studies that have been done, however, we still don't understand why these particular wavelengths work so effectively,'' Ernst said.With a peak power of more than 10 megawatts and an average power level exceeding 10 watts, the FEL is more powerful and brighter than conventional lasers. It also produces light in pulses less than a billionth of a second long. Conventional infrared lasers also generate light in the same frequency range (2 to 10 microns), but their average power level is too low and they cannot produce the necessary pulse structure to cut tissue and bone cleanly, according to Edwards.Copeland led a research effort to define the characteristics of the beam that do the best job of cutting the tissue found in brain tumors. His goal is to vaporize the tumor while minimizing the heat damage to healthy tissue.At the same time biomedical engineer E. Duco Jansen has been working with Copeland to develop a beam delivery system that is safe, efficient and comfortable enough to use in such delicate operations. Jansen found that fiberoptic cables are not suitable for this use - they would melt if exposed to the peak power levels of the FEL beam.So he took advantage of hollow glass tubes called waveguides, developed by James Harrington of Rutgers University, to do the job. The waveguides are small, lightweight and flexible. A highly reflective coating on the interior bends the light, allowing the surgeon to reach most of the areas of the surgical field. The hand piece that Jansen designed has a lens that focuses the beam down to a 0.2 millimeter spot, the size required to concentrate the beam for effective tissue removal. In 1995, an award from the W.M. Keck Foundation allowed the FEL center to add two human operating suites. Before they could perform surgery on human patients, however, the physicists had to improve the reliability of the FEL beam. William Gabella, associate director of operations, led this effort.In order to do surgery we have to guarantee that the beam will stay on for the next four hours,'' Ernst said. In the last year the Vanderbilt FEL delivered more than 2,000 hours of beam time to facility users. Gabella and his team have demonstrated a reliability approaching that of conventional lasers. For the four days preceding the operation, they put the beam through an intensive series of tests and calibrations designed to ensure that it ran correctly.The initial operation was designed to be the safest possible test of the FEL's capabilities. Whitaker had a tumor of a type that can be removed using traditional methods with a high success rate. Copeland opened the skull using traditional techniques. He only used the FEL to cut away a small amount of material from the center of the tumor. The rest he cut out using a scalpel.Ultimately, Vanderbilt neurosurgeons hope to use the University's free-electron laser with a computer-assisted guidance system to remove tiny brain tumors near vital nerves and arteries that are too risky to pursue with conventional medical lasers or by traditional brain surgery.The role of the Vanderbilt FEL center is to explore and refine medical uses for infrared laser light. Some of these applications will be based on the clean cutting of soft tissue. Other uses may include welding tissue to assist in wound healing, repairing nerves, reattaching retinas, or monitoring neurological activity - whatever applications that are found where infrared light proves superior to other wavelengths.Surgeons at Vanderbilt University Medical Center used a powerful laser originally developed for the "Star Wars" missile defense program to help remove a golf ball-sized tumor from the surface of a patient's brain.Dr.Michael Copeland, a former VUMC neurosurgeon led the procedure to remove a three centimeter-wide benign mass from Virginia Whitaker's right temporal lobe. Copeland and the surgical team, used the FEL to cut out a sugar cube-sized piece of the tumor before removing the remaining portion using conventional neurosurgical methods.Earlier studies which suggested that a particular wavelength of laser light generated by the FEL causes little collateral damage to tissues surrounding the target site. It's that potential for collateral damage that has until now limited the use of lasers in brain surgery. Being the first person to ever undergo such a procedure didn't frighten Whitaker.
2021 07 14
Logical Like a Laser Light -
grand displays of devotionsilken crescendos of emotionsipping beet red love potion*CLICK*logical like a laser light — — — —there's work to do here,from A to B.crisp right angles, (nothing obtuse),boxing in the whimto go skipping down the primrose pathof dalliance.Tread. Tread softly over my fragile loves, Reason. Pain in the ass. No, they do not comport with your arithmetic,your letter of the law. So what?By the graces!the most elevated reason to createis out of love!not for money. not for fame.not for accolades.*CLICK*logical like a laser light — — — —Beautiful dreamer. Pain in the ass. Put your number mind to work. Hitch it to some profitable scheme. Not true to you? Fake it. Sing loud enough, "IT'S ART!"Somebody's sure to believe!They will believe!Preach it with verve!Matters not the primary reason you createis for pay?But…when the only material that will do is gold,Or the most meaningful medium is marble,When the work exceeds the wage and ideas spill sacred,The last logical thing:live it like a laser light.Focused — Unwavering — Burning up the extra —You must listen. You must heed. You must bring it forthin a manner befitting divinity. Ideas are plucked from the infinite. Time invested is on loan from the infinite.What is infinity if not divine?Divinely made,Divinely dreamed,Divinely lived,Divinely beamed,logical to me — — — like a laser light• RELATED QUESTIONWill laser light replace LED light in the future? What will be its advantages and disadvantages?According to me some researcher are working on laser light.But according to me laser light will not take place.XED and OLED can take place after 4u20136 years. But still you want to know about advantages of laser lightYou can refer following link..What Comes After LED in the Lighting Industry?Dj laser light for the best disco showDJ laser light for the best disco show Odds are that you have been to a disco clubhouse before or you might have seen the inside of a night club. Did you see the sparkling lights and lighting effects? Yeah, some of them are called DJ laser lights. Light has been known to induce a feeling of happiness and excitement in humans, especially in the nighttime, (try staying in the dark for longer times to verify this claim). It is this simple but effective technique that DJ laser lights offer. DJ lasers take your disco show to the next level. It takes it from "boring" to "bawling". From Nightclubs to Mobile DJ events, a laser light show with effects like starry nights or fireflies is mesmerising, to say the least. You can choose from a range of lighting effects available on the market today. The beam effects, gobos, flower effects, centrepiece effects, scanners, barrel mirror effects, police beacons, and disco balls are several lighting effects that can add value to your disco show. These effects can be used alone or paired with other effects. If the costing is not an issue, you can also consider adding some atmospheric effects like fog, haze, and bubbles to your disco show; and of course - lasers! There are some hi-end quality DJ lasers such as Clubmax 3000 FB4, Clubmax 6000 FB4 and even high power Clubamx 10 FB that outputs 10W of precision laser power. But.. Is that really what you need? A DJ Laser is not a particular type of laser light, but it defines the field of use for lasers. DJ Lasers generally are all in the semi-professional range and although some of them come with sound-to-light and standalone settings, not much control options beyond those are available. DJ lasers should have at least a control option for DMX. Since there is no clear definition, DJ lasers are considered to be less-professional lasers. For the entertainer on the go, a DJ laser is perfect lighting device. Laser systems for DJ shows are portable, light, extremely easy to use and are therefore the ideal lighting apparatus for mobile DJs, entertainers and musicians. DJ lasers can project single or multi-colour beams and room-filling effects in clubs, bars, pubs and private parties to impress audiences. DJ laser light systems can be used with or without fog systems, as well as bounce mirrors, projection screens and other equipment to create bounced laser beams and animated effects and patterns on walls and ceilings. With all these factors in mind, selecting the perfect DJ laser for the best disco show can be a pain in the neck sometimes. It requires setting priorities, identifying main purposes, handpicking the needed features, estimating the number of audiences, stating the coverage area, mapping out positions for the lasers, compromising on some functionalities, and proper consideration of your pocket (of course). So, it is serious business after all. Whether you are looking to light a band, DJ show, or nightclub, there's a huge range of lighting effects and equipment available today to match your budget and the mood you want to create. However, if it's the case that even as a DJ you need a professional-looking laser shows, look no further. Our Clubmax range is exactly what you need!Why is a laser light coherent and converging?The coherence of laser light is created by the mirrors.In elementary textbooks, 'coherence" means spatial coherence. Beware of grade-school textbooks which pretend that the coherence is caused by 'in-phase light waves. " That's actually a widespread misconception. In-phase light only explains the transparency of the laser material. (For example, when light passes through glass, the molecules of the glass all radiate light in-phase, which causes glass to be transparent, but with a lowered velocity of propagation. )This common textbook diagram is wrong:INCORRECT DIAGRAM ABOVE: LIGHT WAVES DON'T WIGGLE SIDEWAYS!Here is one diagram for correctly explaining the nature of coherence:CORRECT DIAGRAM ABOVE: LIGHT FROM PINHOLES IS COHERENT LIGHTLaser light is coherent because any incoherent light cannot continue to bounce between the two laser mirrors. The mirrors cause coherent light to be amplified, and incoherent light to be rejected.For example, perfectly parallel light is perfectly coherent. If the two laser mirrors are flat, and facing each other, then only parallel light can continue to bounce back and forth. Any sideways light or converging light, even if it's slightly off, will wander as it bounces, and be lost over the edge of the mirror.In other words, the coherence of laser light originates with the Fabry-Perot cavity (the pair of mirrors. ) Coherence has nothing to do with in-phase stimulated emission, or with phase-locked photons. Those just explain transparency and amplification.Here's how it works. A simple laser with flat, parallel mirrors will create light with parallel rays: 'plane-wave light. " And plane-wave light is perfectly coherent. Sphere-wave light is also coherent. (And plane-wave light is just sphere-wave light, where the radius of the sphere is enormous!) If the light rays are parallel or radial, then the light is coherent. If the light can be focused to converge at a geometrical point, then the light was coherent. For example, light from stars is coherent light. Starlight is far more coherent than the light from the best laser ever built.Why is laser light converging? It isn't. Laser diodes produce diverging (spreading) light, and if your diode laser seems to produce a parallel beam, it's because a tiny lens was inserted in the beam. The small lens converts the diverging beam to parallel. The light coming from laser diodes is always diverging because the diode is tiny, and the diode's exit-mirror is tinier, like a small pinhole, so the light diffracts. Light passing through an extremely small pinhole will always spread out (called Fraunhofer diffraction.)Light from gas lasers, HeNe lasers, it also spreads, because these lasers don't use parallel mirrors. They use a 'confocal" arrangement, where one mirror is concave, and focused on the other flat mirror. This is done so the laser's operation remains stable, and it keeps working even if the glass tube should heat or flex, bending a slight amount. (Lasers with parallel mirrors cannot tolerate even a small bending or misalignment. But lasers with one curved mirror can ignore mechanical distortions unless the distortion becomes quite large. ) But then, why are the beams from HeNe lasers thin and parallel? Because ...lens! The manufacturers always put a converging lens at the output of a HeNe laser tube.See: various designs for laser optical cavities. In these, all of the light seems to come from an ultimately tiny pinpoint. That's the signature of coherent light.Why is a laser light coherent and converging?Novel Optical Fiber Applications: Fiber-delivered laser lighting: cinema, multi-projector displays, and specialty lightingThe emerging commercialization of laser-illuminated cinema, giant screen, and theme park attractions sets the stage for new applications of off-board illumination. Medical and industrial laser markets have been exploiting optical fiber delivery for more than 20 years, with power levels in the welding segment now approaching 100 kW per beamline. However, these lasers are customized, manufactured in low volumes, and very expensive. Relatively little has been invested in high power visible (RGB) lasers for lighting applications. High wall-plug efficiency (WPE) and long lifetimes have made LED the lighting technology of choice for most general lighting and display applications. However, there are emerging needs for which the unique attributes of RGB laser illumination, combined with optical fiber delivery will enable a new class of solid-state lighting. The first of these is digital cinema. More than 120,000 movie screens now use standardized, digital cinema projectors that show movies from encrypted data files instead of 35-mm film. This conversion to digital was an operational advance for the industry but with a notable technological irony. These state-of-the-art digital projectors still use 60-year old technology-hand-blown xenon arc lamps-as their light source. Now that the conversion is nearly complete, major projector OEMs and premium cinema integrators are considering laser-illuminated cinema projection as their next technological advancement. This year will see the first commercial deployments of laser-illuminated projectors from three of the four cinema-projector OEMs: Barco, Christie, and NEC. Systems from Christie and NEC utilize optical fiber delivery. At this early stage, exhibitors are purchasing the technology for trials and promotional purposes, not to save operating expense. But as components and designs mature and production volume builds, RGB laser engines will be deployed in tens of thousands of cinemas. Lasers will replace xenon arc lamps in movie projectors for the same reasons LEDs are replacing traditional lighting-long lifetime and higher wall-plug efficiency. But lasers have additional advantages in that they produce ultra-high spatial brightness, i.e., small optical étendue (mm2-steradian). Lasers deliver all their power from a very small spot in a nearly collimated beam. This unique optical property enables key capabilities for cinema and ultimately for new kinds of specialty solid-state lighting: the ability to input nearly unlimited amounts of RGB light into digital projectors and the ability to deliver kilowatts of visible light via efficient, flexible optical fiber cables (see Fig. 1). The first benefit solves a number of current cinema challenges, such as increasing 3D brightness and lighting giant screens. Fiber delivery will enable new projection and lighting capabilities and applications. Digital cinema is the first, high-volume, standards-driven application for high power RGB lasers, offering a new market opportunity to suppliers able to develop high volume, cost-effective solutions. Minimum system requirements can be summarized as follows: • greater than 20% E to O efficiency at the color module level • Lifetime greater than 25,000 hours at less than 20% roll-off • High spatial brightness; very good beam quality with no laser speckle These requirements have been substantially met by first generation commercial systems, but there is more work to be done before the entire cinema market can be converted to laser and additional markets addressed. For example, extremely large screens and domes-called "giant screen" applications-require two or more projectors per screen. Applications such as the original IMAX 70-mm film theaters must use two projectors per screen, to provide more than twice the brightness of the largest xenon digital projectors and support 3D operation. Ultra-high-power RGB laser illumination, delivered via optical fiber, provides a solution to achieve requisite brightness through a digital projector. Similarly, many theme park attractions must deploy two or more projectors to create high-resolution, virtual reality-like experiences and achieve required brightness. Disney's popular Soarin' attraction, for example, depends on xenon illumination for its breathtaking but visibly dim vistas of California landscapes. Newer rides such as Universal's Transformers 3D have deployed dual digital projectors in more dynamic and complex ways, but they too suffer from the low 3D brightness of underpowered xenon lamp projection on large screens. Flexible fiber delivery from a centralized source is the key to significant increases in brightness, practical multi-projector designs, reduced power consumption, and the elimination of very costly lamp changes. Both of these examples highlight the requirements of high performance, multi-projector applications. Maximum-brightness xenon projectors, at about 30,000 lumens, are also the largest, hottest, and noisiest projectors. Putting 2, 4, 6, or more of them close to each other, the show and the audience, whether in theme park attractions, dome theaters, virtual reality caves or jumbo digital signage displays is either operationally impossible or prohibitively expensive. Heroic approaches to local heat extraction and noise abatement have been tried, but fiber-delivered RGB lasers elegantly solve the problem. The enabling solution for large scale, multi-projector applications, is called off-board illumination (OBI) or fiber-delivered lighting (FDL). Laser light, delivered via fiber, allows a projector and its light source to be independent, separable subsystems. This newly practical remote light delivery concept will stimulate the demand for even higher power RGB lasers for centralized light farm utilities. At that point, fiber delivered solid-state lighting will become practical for large new markets. There are already examples of fiber-delivered lighting in the field. Shipboard systems on some U.S. Navy vessels currently employ metal halide lamps as the light source (see Fig. 2). These lamp-based systems illustrate the opportunity for efficient, cost-effective, high power RGB lasers for remote source lighting (see Table 1). Fiber delivery of an RGB laser light source provides brightness and cost benefits driven by efficient coupling, long life, and high efficiency. The laser-fiber system provides five times the efficiency and ten times the life of a lamp-driven system. The nearly collimated output of a laser engine couples more than 10 times the light into a single large core fiber, which reduces the size, weight, and cost of delivery cables (see Fig. 3 and Table 2). High spatial brightness enables high power and efficient coupling. The beam quality and coupling system of the laser engine determine the type, size, NA, and number of fibers needed for a given system. Initial cinema prototypes were built with low power devices, often with poor beam quality. This required the use of numerous large-core, high-NA fibers. As higher power, better beam quality RGB lasers become available, efficiency will improve and cable costs will come down. For the moment, cinema and multi-projector applications are being deployed with one RGB engine per projector. However, as the benefits of FDL drive demand, new centralized light utilities will evolve. Racks of high power red, green, and blue color modules, supported by industrial-scale power supplies, cooling and 1:n protection, will supply multiple projector heads or laser luminaires. This is the long-term direction of fiber-delivered RGB lasers: creating a new class of solid-state lighting. Industry may still be a long way from cost-effective laser lighting for large markets, but the pending commercialization of and high unit volumes required for laser-illuminated cinema, giant screen, and theme park attractions will set the stage for the emergence of fiber-delivered lighting. The remaining challenges are: 1) steady and continuous cost reduction; 2) development of high-power infrastructure hardware such as cables, connectors, switches, and routers; and 3) the requisite design features including sensors and components to ensure product safety. The most urgent and highly specialized applications will emerge first and then, within 3 to 5 years, centralized laser light utilities and controllable "light-delivery appliances" attached to the ends of safe and cost-effective optical fiber delivery cables could be in widespread use. Bill Beck is the president of BTM Consulting, Hudson, NY;
2021 07 07
Diode Laser Lighting Could Compete with Led, Research Suggests
From EarthTechling's Kristy Hessman :New research shows that diode lasers could eventually compete with light emitting diodes (LEDs) for home and commercial lighting solutions. Sandia National Laboratories recently asked participants to rate various LED and diode laser lighting scenarios and found that in some situations consumers preferred the diode lasers.LEDs are commonly thought of as the most energy-efficient replacements for the century-old incandescent bulbs. What is not often known is that LEDs lose efficiency at currents higher than 0.5 amps. The diode laser actually improves at higher currents, which means it can provide more light than LEDs at higher amps.Not much research had been done with the diode lasers because of a widespread assumption that the lighting it produced was unpleasant to the human eye, according to Sandia. But the studies showed there was a statistically significant preference for the diode-laser-based white light over the warm and cool LED-based white light. There was no statistically significant preference between the diode-laser-based and either the neutral LED-based or incandescent white light.The results aren't expected to cause an immediate shift to diode lasers, according to researchers, as diodes are more expensive to fabricate and both yellow and green laser diodes have a ways to go. The warm white diode laser light that was preferable to consumers is created by a combination of the four laser beams -- yellow, blue, green and red.Related Stories From EarthTechling:Your Guide to Energy Efficient LightingGreen Light Bulbs Put Ohioans To WorkArty Solar Lamp Comes in Fruit FlavorsSolar Powers Funky Light Wire LampEco-Friendly Handcrafted Lamp A Charmer--
2021 07 05
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