SARAH W. JOINS ALL-MARKS!
Sarah W. is the newest full time member of the All-Marks team. Outstanding with communications and marketing, Sarah is a tremendous asset to All-Marks. She will be selling all of our products and job shop services which include laser marking, UID labels and related products, and all manner of product identification. She can be reached at 877.847.8076 ext. 3.
ALL-MARKS IS GROWING!
All-Marks has just been appointed the regional distributor for all Datalogic Automation laser marking products. This includes all green lasers, CO2 lasers, pulsed fiber lasers, UV lasers, DPSS lasers, continuous wave fiber lasers, and more!
Kudos to All-Marks!
ON APPROVED VENDOR LIST
All-Marks is now on the SpaceX approved vendor list for job shop laser marking. SpaceX is also a long time customer of All-Marks, utilizing our industrial laser marking equipment.Link
Laser Marking - An Unexpectedly Bright Idea
Lasers: Few innovations of the past century have changed as many aspects of everyday life as the laser.
A laboratory curiosity at first, there now seems no limit to its usefulness.
For several years after the invention of the laser, Charles Townes' colleagues teased him about its seeming irrelevance to the real world. They told him bluntly that it was "a solution looking for a problem". But Dr. Townes, who later received a Nobel prize for his work in developing the technology, has had the last laugh. Over the past four decades, he has watched the laser emerge from the obscurity of the laboratory to become a ubiquitous technology that is used in an amazing diversity of applications. Lasers can now be found in everything from DVD players to weapons systems, telephone networks to operating theatres.
Lasers pack a powerful punch, and have had a huge impact on society. Today, they guide missiles, point mining equipment in the right direction and enable astronomers to take clearer pictures of the heavens. They also perform myriad mundane tasks, such as powering office printers, removing unwanted body hair and carrying voices from one telephone to another. Lasers are synonymous with precision, from industrial cutting machinery to sights for sniper rifles. Yet the creators of the laser were not so sure what they were aiming at when they began working on the technology back in the 1950s.
The grandfather of the laser was Albert Einstein. In 1917, the great physicist postulated that atoms could be persuaded to emit tiny packets of energy, called photons, in an organized manner though a process of "stimulated emission". But how could this be achieved in practice? The answer came in a flash of inspiration on a park bench, or a middle-of-the-night "Eureka!" moment—depending on whose story you believe.
A tale of two epiphanies
As Dr. Townes tells it, he had his epiphany shortly after dawn on a spring morning in 1951, as he was sitting on a bench in Franklin Park in Washington, DC. He quickly jotted down his idea on a scrap of paper he found in his pocket. "It is perhaps a hackneyed device among dramatists to have a scientist scribble his thinking on the back of an envelope, but that is what I did," he later wrote.
In essence, lasers work by setting up a chain reaction, in which photons of a particular wavelength prompt other atoms to emit further, identical photons. For all of this to work, a suitable material, called a "gain medium"—which can be a solid, a liquid or a gas—is required. To get the process started, the gain medium is "pumped" using a burst of light or an electrical discharge. This excites the atoms in the medium, some of which then emit photons of a specific wavelength. When a photon encounters an excited atom, it may then cause it to emit an identical photon—a process called "stimulated emission". This causes a cascade effect, as each photon stimulates the emission of additional, identical photons. The gain medium acts, in short, as an amplifier of light: hence the name laser, an abbreviation of light amplification by stimulated emission of radiation".
Laser light has several unusual properties. It is monochromatic, since it is made up of identical photons of a specific wavelength, and the wavelength of light is what determines its color. Next, laser light is coherent, which means the peaks and troughs of the light waves are aligned. The light is also emitted in a tight, concentrated beam.
Dr. Townes, who was the head of the Columbia University Radiation Laboratory in New York, applied his idea to generate an invisible beam of microwave radiation, rather than visible light, using ammonia as the gain medium. His team called their device a maser, which is short for "microwave amplification by stimulated emission of radiation". Their first maser was not capable of continuous output, but two Soviet scientists, Nikolai Basov and Aleksan. Dr. Prokhorov, came up with a solution to this problem. They subsequently shared the Nobel prize with Dr. Townes in 1964.
Following the invention of the maser in 1953, the big question was whether the same technique could be applied to visible light. Dr. Townes and his brother-in-law Arthur Schawlow, who worked at the legendary Bell Laboratories, laid out much of the theoretical basis for such an "optical maser" in a paper that appeared in the scientific journal Physical Review in 1958. In particular, they had the idea of putting mirrors at each end of the gain medium to cause photons to bounce back and forth. But by another man's account, the crucial insight that made lasers possible came in the middle of a mild November night in 1957. Gordon Gould, a doctoral student at Columbia under Dr. Townes, sat up in bed when the idea hit him. He says that the flurry of inspiration lasted several days, and he filled over six pages of a notebook with the details of how the light-emitting device would function. In his notes, he was the first to refer to this device as a "laser"; Dr. Townes still preferred the term "optical maser". Dr. Gould rushed off and had the pages notarized at a local sweet shop. But he did not apply for a patent: he wrongly thought he would have to build a working prototype of his design first.
Over the course of a patent war spanning the next 30 years, Dr. Gould told countless courtrooms that Dr. Townes had appropriated his ideas. He also argued that he had always seen the laser's potential in real-world applications—which were poorly outlined in the laser patent granted to Dr. Townes and Dr. Schawlow. In the 1970s and 1980s, Dr. Gould won several important legal battles, and was awarded a number of patents relating to lasers. Neither Dr. Townes nor Dr. Gould constructed the first working laser, however. That happened in 1960, when Theodore Maiman, a physicist at the Hughes Research Laboratories in Malibu, California, finally hit upon the correct configuration of mirrors, gain medium and pumping mechanism to make a working laser—beating Dr. Townes's own team at Columbia, and Dr. Schawlow's at Bell Labs, in the process.
Beaming with success
It is not surprising that Dr. Townes and Dr. Schawlow could not predict what the laser would be used for, since its applications have been so many and varied. "Asking how lasers have influenced modern life is like asking how electricity has influenced modern life," says Lou Bloomfield, a physicist at the University of Virginia in Charlottesville. To start with, it seemed that lasers would be most useful in industry and in scientific research: the first examples had been devised for use in spectroscopy, to probe the properties of matter. But the advent of small, cheap, low-power semiconductor lasers meant they could be incorporated into mass-produced consumer products. Today, such lasers are the most numerous: they can be found at the heart of hundreds of millions of CD and DVD players, PCs and games consoles.
In an optical drive, a laser beam is focused on to the microscopic bumps and pits on the disc's surface. The bumps and pits are formed by injection-molding the plastic disc; its surface is then covered with a very thin reflective coating, and the whole thing is encased in a transparent protective layer. As the disc spins, the laser's light is reflected off the bumps and pits, each of which reflects the light differently. These differences are detected using an optical sensor, which produces a stream of digital information corresponding to the sequence of bumps and pits.
CD and DVD players work in essentially the same way, but DVDs can contain more information, since they are read using laser light of a shorter wavelength (650 nanometers, as opposed to 780 nanometers in the case of CDs). This shorter wavelength allows smaller bumps and pits to be distinguished, which means more of them, and hence more data, can fit on the disc. The next generation of optical drives will be based on blue lasers (with a wavelength of 405 nanometers), providing enough storage capacity for high-definition movies.
Compared with videocassette players, which rely on magnetic tapes and contain lots of complicated and expensive moving parts, laser-based gadgets use cheaper off-the-shelf components, explains Paul Jackson of Forrester, a consultancy. As a result, the prices of DVD players fell far more quickly than those of VCRs. The DVD player became one of the fastest-adopted products in the history of technology: the first players appeared in 1997, but around half the households in the developed world now have one, and the cheapest models cost a mere $40.
Seeing well and looking good
As well as bringing crisper images to television screens, laser technology has also made it easier for people to see them without the help of glasses, thanks to the development of laser eye surgery. As early as the 1960s, the possibility of using the technology in medicine had occurred to researchers such as Leon Goldman, often called the father of medical lasers. He had been asked to evaluate the safety of industrial lasers, and his investigations into the biological effects of lasers led him to consider their use in surgery.
In 1965 doctors first used an argon laser to repair a detached retina, a sight-threatening condition in which the light-sensitive layer of the inner eye becomes separated from its supportive tissue. Focusing a laser on to the retina and making tiny burns produces scar tissue that "welds" the retina back into place. To the laser's inventors, this application of the technology was a completely unexpected development. "I had never heard of a detached retina," says Dr. Townes.
More recently, an increasing number of people have put aside their glasses and contact lenses to take advantage of a speedy procedure known as "laser-assisted in situ keratomileusis", better known as LASIK. Around 2m people in America alone will undergo the operation this year to correct near- or far-sightedness. During LASIK surgery, an instrument cuts a thin flap in the outer portion of the eye, called the cornea. This flap is then peeled back, allowing laser pulses to vaporise and remove a microscopic portion of the underlying tissue, thus reshaping the cornea. Since it is the shape of the cornea that determines how near- or far-sighted someone is, this reshaping has the effect of correcting the patient's vision and reducing the need for glasses or contact lenses.
Lasers have many other surgical uses, too. They have been adapted to zap away spider veins, warts and wrinkles. "The impact of lasers and laser-like technology in dermatology over the last 20 years has been nothing short of miraculous," says David Goldberg, who is the director of laser research at the Mount Sinai School of Medicine in New York. A tiny beam can be used to heat up a wrinkle, for example, and collagen proteins, which have a firming effect, are then produced as part of the skin's healing mechanism. As people become older, richer and vainer across the developed world, researchers are devoting a lot of attention to improving such cosmetic procedures.
Lasers also have less frivolous medical uses, of course, not just improving people's appearances, but also saving lives. They can be used to zap tumors, remove polyps and stem bleeding. Lasers are more precise than conventional surgical instruments, doing less damage and allowing for faster healing and recovery. By directing a beam along a flexible optical fiber, they can even be used inside the body.
Laser pulses traveling along optical fibers can heal, but are better known for carrying information. In 1988 the first transatlantic fiber-optic cable went into service, and such cables have since redefined the economics of telecommunications. "If you look at a world map now, it's just a spider web of these undersea cables," says Paul Shumate, executive director of the Laser and Electro-Optics Society at the Institute of Electrical and Electronics Engineers (IEEE). "In 1975 there wasn't a fiber in the telephone network. Now, 30 years later, there's hardly any copper except at the last connection from the curb." Stephen Anderson, editor-in-chief of Laser Focus World, an industry journal, points out that people have forgotten the challenges of making transatlantic calls. As recently as 40 years ago, such calls required a lot of organization. "Bookings were made two days in advance, and you were lucky if you could understand one another," he says. During the 1990s, enthusiasm for fiber networks led to an enormous overbuild, huge overcapacity, and plunging prices. The result was meltdown for the telecoms industry, but far cheaper and easier communications for its customers.
Using several lasers, each with a different wavelength or color, it is possible to send multiple streams of data down a single optical fiber—a trick called "wavelength division multiplexing". Improving the precision with which particular colors of laser light can be generated—in particular, through careful temperature control—therefore has the effect of increasing the capacity of a fiber. At the beginning of the 1980s, fibers carried a single stream of data at 45 megabits per second, says Dr. Shumate. The capacity of each stream has since increased to 10 gigabits per second, and researchers have achieved speeds of 40 gigabits per second in laboratory conditions. Sending dozens of such streams, using many slightly different wavelengths, down a single fiber increases its capacity to several terabits (millions of megabits). Improvements in laser technology, in short, have increased the capacity of networks without the need to lay any new fiber.
New ways to use lasers continue to proliferate—and one of them might even be coming to a supermarket near you. Retailers already use laser scanners to read bar-codes. But Sherwood Technology, a firm based in Widnes, Britain, has devised a system called "DataLase" that uses lasers to write prices, dates and other information on to fruits, vegetables, pills and even confectionery. An edible, light-sensitive coating is applied to the surface and then drawn on using a low-power laser, which causes the coating to change color. It is yet another example of the way that new uses continue to be developed for lasers, decades after their invention.
The lesson of the laser
And therein lies a lesson. The technology was originally developed for use in spectroscopy, and its myriad other uses were an unexpected bonus. "People just didn't imagine the many applications which now seem so obvious," says Dr. Townes. "But that's a characteristic of most really brand new ideas." Dr. Schawlow has even suggested that trying to anticipate the possible uses for the laser might have hindered its development. "We had no application in mind," he said in 1981. "If we had, it might have hampered us and not worked out as well."
Some people worry that the research climate that produced this fundamental technology—one that allowed bright minds to pursue abstract ideas—has become regrettably rare. Dr. Bloomfield, who himself once worked at Bell Labs, feels that today's corporate research laboratories tend to have a shortsighted view, focusing only on the next six months. "More and more, everyone's waiting for someone else to do the pioneering work and hoping to take advantage of other people's foresight," he says.
The laser is an object lesson in the value of blue-sky research, and a reminder that even a seemingly obscure technology can go on to have an extraordinary range of uses. So has Dr. Townes ventured back to the Franklin Park bench since the morning he came up with his breakthrough idea? No, he admits, but perhaps it would lead to new insights. "I probably ought to go back," he says.