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Glossary of Terminology

Laser safety overview

Other applications of lasers

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Laser Science Projects

Other Applications of Lasers

    When lasers were first invented in the 60's they were described as "a solution looking for a problem". These days lasers are useful tools in our everyday life. While laser light show applications are the most visible and the most fun, here are just a few of the many other useful (non laser show) applications of lasers:

Laser being used for tunnel construction
  • Probably the most common application of lasers is their use in CD and DVD players.  A tiny spot of laser light from a diode laser is focused onto the spinning plastic disk which has a metalized coating.  The coating has a series of "lands" and "pits" in it which represents the digital data stored on the disk.  The strength of the reflections of the laser by the disk surface, is read by a photo detector and conversed into a stream of "1" and "0" signals, fed to the computer or decoder chip, which then converts it back into the original data.
  • Construction applications where pipes or rails must be laid on a very straight line use the beam of a low power laser as a guide. In digging underground, the centre of a tunnel can be kept accurately aligned with a laser beam (see photo - left).  Home construction also uses a laser device with a spinning mirror that can project a line around a room allowing for accurate placement of windows, doors or even electrical outlets.
  • Lasers are used to align drills and rivet machines, a laser dot shows the operator where the hole or rivet will be placed. Similarly, a line of laser light projected onto the material can show a saw operator where the cut will occur in the material.
  • Holography is the production of a 3D photograph using a laser as the source of illumination. Holographic images can be artistic as well as practical allowing the study of fragile objects which can not withstand repeated handling. Holograms can also be used for vibration and stress analysis allowing the detection of hidden defects in materials such as aircraft parts long before they become a problem. Commercial aircraft tires and high performance automotive tires are tested this way.  Beacuse holograms are difficult and expensive to reproduce, they are used on credit cards and certain product pckages as a verification that the item is an original.
  • You are probably familiar with the bar code scanner in your local supermarket or store. These units scan a pattern of red light from a low power HeNe or diode onto a window or out of a small hand held unit. The reflections from the UPC (Universal Product Code) on the products placed or dragged across the window are detected. The reflections are converted into computer code and fed to the cash register. This looks up the product, charges you the correct price, prints the sales slip and also keeps track of the inventory so that the store will know when to re-order popular items.
  • In manufacturing, scanned laser beams can be used for non-contact defect detection where more or less light is reflected from moving material if a defect is present.  Lasers can also be used to rapidly check the size or parts in automated manufacturing to insure they are within tolerances.
Lasers allow for light wave communications. In the simplest set-up, a laser is modulated by a microphone and electronics, then projected toward a photo-detector connected to an amplifier. This allows for communications in a more secure manner as an interceptor would have to interrupt the laser beam to tap into the communications.  The down side is that such communications have to be line-of-sight and weather conditions can block or attenuate the laser beam making communications unreliable.
  On TV and in the movies, you often see laser eavesdropping devices.  This is because the red or green beam looks good in the picture.  In reality, an invisible infrared laser beam is used to that the person being spied on will not be tipped off by seeing the laser coming through the window.  These devices work by detecting variations in the reflections of the laser beam form the window glass caused by vibrations.  A person speaking inside a room will cause minute vibrations in the glass which can be detected and reconstructed into audio data.

    In most laser based communications systems, the laser beam is conducted by a glass fiber optic usually no thicker than a human hair (see photo - right). As light operates at much higher frequencies and speeds than the voice and data information it carries, many conversations or data transmissions can be multiplexed (encoded) onto one fiber optic.  By using different laser lines (colours) and encoding many transmissions onto each line, thousands of transmissions can be carried on a single hair thin glass fiber as in modern telephone and data backbone systems.
    Much of the information you access through the Internet is transmitted by fiber optic cables from major node to major node and even to your ISP.  At the ISP or major nodes, the data can be recovered form the fiber optic and then sent along DSL or Cable lines to your home or school.  These transmitters use high speed modulation of laser diodes to send the data thought the fibers.  The data is converted from light to electronics at the receiving end; the server is queried, the page you requested is converted from electronic impulses to light impulses; sent to your ISP, which then converts it back to electronic signals that are forwarded to your computer (this is a simplified explanation that omits routing issues).

   Some other everyday applications of lasers include frame straightening on unibody cars; accurate flatness measurements; CD (Compact Disk) and DVD mastering and manufacturing; video disk playback, physics experiments and research with diffraction and interference; fusion research; cutting & marking in manufacturing applications; measuring the diameter of small wires or other parts; trimming & welding computer chips and other semi-conductors; high speed and high quality printing systems; and blood cell counting.


Medical Laser Applications

   This brings us to a special area of laser applications that benefit many people, medical uses. High power Carbon Dioxide lasers, which emit powerful beams of infrared (heat) energy, can be conducted through fiber optics for use as 'bloodless scalpels`.  As the laser cuts, it cauterizes (seals) the small blood vessels in the flesh preventing blood loss, allowing the doctor a clearer view of the incision, and reducing the risk of infection in delicate surgery. This type of laser can also be used to cauterize warts and lesions
    Using lower powers and different colours (frequencies) of laser light, lasers can vaporise pigments without affecting the surrounding skin allowing for the reduction or removal of tattoos or birthmarks.  The carbon particles created by the vaporisation of the pigments are carried away by the bloodstream.  Lasers can also be used to vaporize a very thing layer of the skin to remove blemishes or acne scars.
    Lasers are used in eye surgery. An ophthalmologist (eye doctor) can 'weld' a detached retina into place with a laser beam stabilizing or improving vision. The doctor first uses a low power laser as a 'sight' to aim the equipment then fires pulses from a more powerful laser at the retina. These pulses are focused by the lens of the eye and cause lesions and scar tissue on the retina at the back of the eye. As the scar tissue heals, it tends to shrink pulling the retina back into place and holding it there.

        Laser PRK (Photorefractive Keratectomy) is a process that uses lasers to re-shape the contour of the lens in the eye. Formerly delicate surgery was used to cut a series of fine slits in the lens causing it to change thickness and hence focus. This meant that certain visions problems, like short-sighted, could be cured. Now lasers are used to ablate [burn away] small areas of the lens to change it's focus and improve vision for thousands without surgical intervention.
    Recent advances in the development of photo-sensitive dies which respond only to certain frequencies (colours) of light have brought new cancer treatments especially for brain cancer. The brain is a very delicate area where traditional surgical approaches can do more damage that they repair. Doctors can now inject a patient with a special die that binds only to cancerous brain cells, and which absorbs only certain frequencies (colours) of laser light. By drilling a small hole in the scull and inserting a thin fiber optic probe, the cancerous cells (which have absorbed the die) can be destroyed by high power laser pulses with minimal damage to other nearby brain structures.

    New applications for lasers and laser based technology are appearing all the time. If you are interested in keeping up with this growing field, subscribe to, or visit the web site of, one of the trade journals such as Photonics Spectra or Laser Focus World.


[ Introduction | Bibliography | Glossary of Terminology | Laser safety overview | Other applications of lasers | Selected laser related web sites | Basic laser science projects | Intermediate laser science projects | Advanced laser science projects | Illustrations for laser science projects ]


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