Not many would knownow that “Laser” is an acronym for – ‘light amplification by stimulated emission of radiation’. Lasers are way beyond than powerful flashlights. The lasers are the special amaze balls that possess a powerful light beam suffice to zoom miles into the sky or cut through slabs of metal. Although they appear to be recent inventions, but they've been with us over half a century: the concept was discovered in 1958; while the first practical laser was created in 1960.

In that period, lasers were stupendous examples of spearhead science: secret agent 007, James Bond, was almost hacked half by a laser beam in the movie Goldfinger. But besides Bond villains, no-one had any idea what to do with lasers. Today, we all have the famous lasers in our homes (CCTV cameras) in movie halls (projectors), in our offices (in laser printers), and in shopping stores (in barcode scanners). Our eyesight is fixed with lasers, and the emails we receive and send over the Internet with signals happens with lasers firing down fiber-optic cables.


How laser works?

Whether we understand or not, all of us use lasers all day long, but how many of us really realize what they actually are or how they work?

The basic concept of a laser is simple. It's a tube type device that ponders light over and over again until it materializes in all- powerful beam. But how does this come up, exactly? What's goes on inside a laser? Let's take a closer look!

A laser is produced when the electrons in atoms in special glasses, gases or crystals soaks up the power from an electrical current or another laser and become “enthusiastic.” These enthusiastic electrons travel from a lower-energy ambit to a higher-energy ambit encircling the atom’s nucleus. When they resume to their usual or “ground” state, the electrons release photons (particles of light).

All at the same wavelength, these photons are also “lucid,” meaning the crests and troughs of the light waves are all in lockstep. As opposed, normal visible light consisting miscellaneous of wavelengths and is not lucid.

Laser light is unique and distinguished from the ordinary light in other ways as well. First, the light in laser comprises of only one wavelength (one particular color). The specific wavelength of light is recognized by the amount of energy discharged when the enthusiastic electron falls to a lower orbit. Second being, laser light is directional to the target. WhenIn so much as, a laser produces a very tight beam, a flashlight generates light, that is scattered. Because laser light is lucid, it remains concentrated for long distances, even to the moon and back.

A laser is an electric instrument which creates exceptionally directional light. It releases light through a process called stimulated emission of radiation which raises the intensity of light.

The light waves of usual light sources have various wavelengths. Thus, the photons released by usual light sources are out of phase. Hence, ordinary light is non-lucid.

Whereas, the light waves emitted by laser light have only single wavelength. Thereby, all the photons discharged by laser light are all in phase. Hence, laser light is lucid.

The light waves from laser comprises of only one color or wavelength so it is called as monochromatic light.

The laser has a tapered laser beam which can be focused on a very small area. This makes laser light largely directional.

The laser light diffuses in a small area of space. Thus, the complete energy is concentrated over a compact region. Hence, laser light has much higher intensity than the ordinary light.

So, how is laser different from the classical light sources? It is contrasting four ways i.e.:

  • Lucidity
  • Directionality
  • High Intensity
  • Monochrome or Uniformity

Different types of lasers

There are various types of lasers available for research, medical, and commercial uses. Lasers are commonly classified by the kind of lasing medium they employ - solid state, gas, semiconductor dye, or excimer.


LASER CLASSIFICATION
  • Solid state lasers: This type of laser have lasing substance dispersed in a solid matrix, emitting infrared light e.g., the ruby or neodymium-YAG (yttrium aluminum garnet) lasers.
  • Gas lasers: The most common form of gas lasers include the helium and helium-neon, HeNe lasers that have a first output of a visible red light. CO2 lasers throw off energy in the far-infrared, 10.6 micrometers, and are utilized for cutting tough materials.
  • Semiconductor lasers: Sometimes referred to as diode lasers, are not solid-state lasers. These electronic instruments are usually are very small and employ low power. They may be constructed into larger assemblages, e.g., CD players (compact disk players), DVD players (Digital Video Disc), and the writing source in some laser printers.
  • Dye lasers: These utilize intricate organic dyes like rhodamine 6G in liquid solutions or suspension as lasing media. They are adjustable over a wide radius of wavelengths.
  • Excimer lasers: The name is actually extracted from the terms excited and dimmers. It utilizes reactive gases like fluorine and chlorine blended with inert gases such as krypton, argon, or xenon. When electrically triggered, a pseudo molecule or dimer is generated and when lased, it generates light in the UV range.

Lasers are also further classified by the duration of laser emission – persistent wave or pulsed laser— CONTINUOUS WAVE (CW), SINGLE PULSED (normal mode), SINGLE PULSED Q-SWITCHED, REPETITIVELY PULSED or SCANNING LASERS, MODE LOCKED lasers.

In addition, Lasers are classified with respect to their information of danger & caution based on power, pulse duration and wavelength. However, when provided the specifications of laser or laser system, it is complex to apply.

Classes of Lasers (adopted from ANSI Z-136.1-2007)

Class 1: Not competent for emission of excess of the Class 1 Accessible Emission Limit (AEL), thus no hazard of causing damage to the eye (unless unassembled). An example of a Class 1 laser product is CD Rom players.

Class 1M: Same norm for categorization as Class 1 but where beam may be dangerous for viewing with magnification.

Class 2: Capable for emission of accessible radiant energy not exceeding the Class 1 AEL for any pulse duration < 0.25 s (time estimated to blink). Viewing output of the laser is not expected. Supermarket point-of-sale scanner is an example of a Class 2a laser.


Different applications of laser in medicine

Lasers have a wide and increasing array of applications in medicine. Lasers can reshape corneas, ream arteries, pulverize gallstones+ and destroy tumors. Their growing use in medicine is aroused by high-grade techniques and better interaction of laser light with living tissue. Lasers for Medical Applications amass the possible choice of these devices on the basis of principles, methodologies and application of lasers in diagnostics, therapeutic branch of medicines and surgery.


Medical Applications of Lasers

  • Cleaning Arteries with Light: lasers are progressively used to clean plaque from arteries. Plaque is a rigid fatty compound that keeps building inside walls of the arteries, leading blocking blood vessels and eventually resulting in stroke or heart attack or stroke, both of which are serious and sometimes lethal. The classical way of removing the plaque involves opening the chest and making cuts, a lengthy, costly and sometimes risky operation. Lasers have appeared to be an effective alternative in burning away the plaque using a laser beam. A tiny laser is used by a surgeon to cut away tissue in a gallbladder operation. The laser and a tiny fiber-optic camera are inserted into the navel, so no abdominal cut is required.

  • Lasers healing and reshaping the Eyes: Some of the notable leap forwards for medical lasers; have been in the area of ophthalmology, the structure and diseases of the eye. Main logic of laser beams being so useful in treating the eye is that the cornea (the coating that covers the eyeball and grants light into the interior of the eye), is transparent. Since it is created in a way to grant normal light, the cornea lets in laser light just as well and is not hampered by the beam.

  • Lasers for Eye Surgery: The laser operates similar to a sewing machine to fix a detached retina, the thin, light-sensitive membrane that lines the interior of the eye. The laser beam is tuned as to make it pass harmlessly through the lens and concentrate on tiny spots near the damaged region of the retina. When it is concentrated, the beam has the strength to "weld" or seal the loosened region of the retina back against the wall of the eyeball.

    Perhaps the most amazing of all the eye-related laser applications is the reshaping of the eye's cornea, a technology known as LASIK (which stands for L aser- A ssisted I n S itu K eratomilensis). The patient's eyeglass is precisely carved inside the cornea using the excimer laser beam.

    In addition to treating loosened retinas, lasers can also remove cataracts. A patient undergoes eye surgery performed by a laser beam. In addition to treating detached retinas, lasers can remove cataracts.

    Another condition that is treatable with laser application is glaucoma, which is described by the formation of fluid in the eye that affects vision; and sometimes causes blindness. Surgeons now turn to laser to avoid conventional surgery for eyes impaired with glaucoma. The laser thumps a hole in a preplanned spot and the fluid is discharged out of the hole.

  • Laser for Birthmark removal: An argon laser is used to remove a port-wine stain, a type of birthmark, most commonly found on face and neck. The Unwanted tissue is blazed away while the skin remains uninjured.

  • Laser-Assisted Dentistry: Dentistry is another branch of medicine that has been benefited remarkably from laser technology. Lasers have indeed made many people stop trembling about visiting to the dentist. Nd-YAG laser that uses a crystal for its lasing medium which is used instead of a drill for most cavities. It removes the decayed tissue without harmongthe enamel and with just NO pain.

  • Laser imaging and diagnosis: Lasers have a crucial role in the early detection of cancer, skin cancer, melanoma detection, as well as many other diseases using IR lasers.

  • Laser-based X-rays: Laser systems are increasingly replacing the traditional x-rays used in mammography with fast laser pulses to image breasts, brain as well as other parts of the body.
  • Laser Hair Removal