One of the major scientific discoveries of the twentieth century was the capacity to control and use laser energy. Few innovations or advances in any branch of science have ever had such a dramatic influence as the science of lasers.
A laser is a highly concentrated and narrow beam of light. However, it is not your average type of light. It is a distinct form of light with distinct features and properties.
Lasers may be utilized to conduct a broad variety of jobs because we have learned to control and emit the lasers in a controlled manner.
Lasers with fine control and excellent accuracy are commonly employed in medicine. Medical lasers are capable of performing extremely accurate and sensitive treatments in a wide variety of therapeutic, surgical, and clinical diagnostic procedures.
Bloodless surgery, laser tissue welding, vaporization of tissues, coagulation of large blood vessels, cutting and volume ablation of tissues, laser scanning cytometry, low-level laser therapy, ablating tumors, kidney stone treatments, photo bio-stimulation, laser wound healing, ophthalmic surgery, scar revision, tattoo ablation, and hair removal are some examples .
The History of Medical Lasers
Following that, in 1939, Valentin A. Fabrikant proposed the use of stimulated emission to amplify short electromagnetic waves.
Willis Lamb and R.C. Retherford discovered apparent stimulated emission in hydrogen spectra in 1947 and were the first to show it.
Alfred Kastler, a physicist, proposed the notion of employing an optical source of energy to excite a material and cause emission in 1950. Two years later, he and his colleagues Brossel and Winter were able to effectively test their proposed procedures for the first time, confirming their idea.
The first laser was built in 1960 by Dr. T. H. Maiman at Hughes Aircraft Company, using a synthetic ruby rod stimulated by high intensity flash lamps, which generated millisecond pulses of coherent 694nm (near-infrared) ruby laser (red) light. Shortly afterwards, 1060nm laser light was generated by stimulating glass rods doped with Neodymium (Nd:Glass laser).
The First Use of Lasers in Medicine
Within a year, pioneers such as Dr. Leon Goldman began research on the interaction of laser light on biologic systems, including early clinical studies on humans. Interest in medical applications was intense, but the difficulty controlling the power output and delivery of laser energy, as well as the relatively poor absorption of these red and infrared wavelengths led to inconsistent and disappointing results in early experiments.
The exception was the application of the ruby laser in retinal surgery in the mid-1960s. In 1964, the Argon Ion laser was developed. This continuous wave 488nm (blue-green) gas laser was easy to control, and its high absorption by hemoglobin made it well suited to retinal surgery, soon making clinical systems for treatment of retinal diseases available.
The Word “LASER” is Born
Gordon Gould, a graduate student at Columbia University, was working on his PhD thesis regarding the energy levels of excited thallium atoms at the same time. In November 1957, he formed some thoughts and wrote notes regarding “laser” while working on his thesis. He also recommended utilizing an open optical resonator in his notes, which became a key component of subsequent laser systems.
Gould coined the term “laser” for the first time. He popularized the word “laser” in his 1959 conference presentation “The LASER, Light Amplification by Stimulated Emission of Radiation.”
Gould’s concept was for “aser” to be a suffix that would be used with an appropriate prefix based on the radiation spectrum emitted by the device. For example, xaser is used to describe x-ray emitting devices, uvaser is used to describe ultra violet emitting devices, raser is used to describe radio-frequency emitting devices, and so on.
Gould’s study also discussed potential laser uses such as spectroscopy, interferometry, radar, and nuclear fusion. He then continued to work on refining his concepts.
Lasers in Dermatology
In 1963, a dermatologist named Goldman was the first to test the effect of laser light on the skin.During his investigations, he discovered that melanin absorbs light preferentially
Later studies revealed that when using Q switching lasers, the damage threshold of pigmented lesions was unaffected by skin color. As a result, he believed that selective injury at the melanosome level was feasible.
It took 20 years but Dover finally proved that the selective death of melanosomes is pulse-width dependent. He used varied pulse width lasers to irradiate melanosomes and studied them under an electron microscope.
He discovered that the interior structure of the melanosomes treated with long pulses was not destructed. But, the internal structure of the melanosomes treated with short pulses was destructed. His theory from 1963, was in fact, correct.
Achievements in Laser Science
Since the invention of the laser, scientists have been actively investigating, developing, and upgrading laser technology. They have been consistently presenting new concepts for manufacturing various laser systems and laser beams.
They have identified novel materials that emit varied wavelengths, increasing the variety of alternative methods to harness laser light. They have worked tirelessly to advance laser systems, increasing the efficiency of laser machines, boosting laser power, and expanding our knowledge and talents in the disciplines of laser. And the benefits have been enormous.
Nd:YAG and CO2 Lasers
In 1964, the Nd:YAG (Neodymium:Yttrium Aluminum Garnet) laser and CO2 (Carbon Dioxide) laser were developed at Bell Laboratories.
The CO2 laser is a continuous wave gas laser, and emits infrared light at 10600nm in an easily manipulated, focused beam that is well absorbed by water. Because soft tissue consists mostly of water, researchers found that a CO2 laser beam could cut tissue like a scalpel, but with minimal blood loss.
The surgical uses of this laser were investigated extensively from 1967-1970 by pioneers such as Dr. Thomas Polanyi and Geza Jako, and in the early 1970s, use of the CO2 laser in ENT and gynecologic surgery became well established, though limited to academic and teaching hospitals.
Dye Lasers, CO2 Lasers and Nd:YAG Lasers
Dye lasers became available in 1969, along with noble gas-halide, or Excimer lasers, in 1975. Since then, many other different laser systems have become available for industrial scientific and telecommunications applications, as well as medical uses.
In the early 1980s, smaller but more powerful lasers became available, and were soon appearing in community hospitals and even physicians’ offices. Most of these systems were CO2 lasers used for cutting and vaporizing, and Argon lasers for ophthalmic use.
Nd:YAG and KTP laser systems were used by larger hospitals for the new field of laparoscopic surgery. These “second generation” lasers were all continuous wave, or CW systems, which tended to cause non-selective heat injury, and proper use required a long “learning curve” and experienced laser surgeons.
Pulsed Dye Lasers
The single most significant advance in the use of medical lasers was the concept of “pulsing” the laser beam, which allowed selective destruction of abnormal or undesired tissue, while leaving surrounding normal tissue undisturbed.
The first lasers to fully exploit this principal of “selective thermolysis” were the pulsed dye lasers introduced in the late 1980s for the treatment of port wine stains and strawberry marks in children, followed by the first Q-switched lasers for tattoo removal.
Another major advance was the introduction of scanning devices in the early 1990s, enabling precision computerized control of laser beams. Scanned, pulsed lasers revolutionized the practice of plastic and cosmetic surgery by making safe, consistent laser resurfacing possible, as well as increasing public awareness of laser medicine and surgery.
The Future of Lasers
Laser are now widely utilized and depended on in virtually every aspect of modern civilization, including consumer electronics, telecommunications, industry, construction, science, medical, dentistry, education, law enforcement, law enforcement, and the military. The use of lasers is increasing at a rapid pace.
Medical lasers have made it possible to treat conditions previously considered untreatable, or difficult to treat. Patients benefit by improved results and less cost. In the last few years, the main focus of research and development of medical lasers has been on laser hair removal, the treatment of vascular lesions including leg veins, and vision correction. The thrust of current research is directed towards non-ablative laser resurfacing (“laser skin toning”), “no-touch” computerized vision correction, and improved photodynamic therapy for treatment of skin cancer and for hair removal.