Lasers

By Alison Warren

     Lasers are found today in all types of products and technology, from CD players to dental drills to laser light shows. Fabulous Works, Inc. now incorporates laser, music, and firework computer synchronization into our fabulous shows!  If you have ever had any questions about lasers, I am the laser specialist at Fabulous Works, Inc. so please continue reading.  Although most people in today’s society have heard of lasers, or seen one at some point, the surprising fact is that very few know how they work. In this section, I will try to answer some of the basic questions about lasers and laser light shows.

What are lasers?

     The term laser is an acronym for Light Amplification by Simulated Emission of Radiation.  Lasers are essentially devices that control how energized atoms release photons.

How do they work?

     Most lasers, although there are many types, have the same essential features.  In a laser, very intense flashes of light or electrical discharges pump the lasing medium to get the atoms into an excited state.  When this happens, the electrons from the atom move from a lower-energy orbital to a higher-energy orbital.  In order for the laser to work, there have to be a large number of atoms in an excited state two or three levels above the ground state.

Electrons can also release energy after being excited, as shown in the diagram above, in the form of photons, or light energy.  Photons have a very specific wavelength which is determined by the state of the electron’s energy when the photon is released.  The wavelength of the photon determines the color of the light emitted by the atom.

One of the key elements to how a laser works is that the photon emission is organized, meaning it is stimulated.  This occurs through several steps.  If a photon that was emitted runs into an atom with an electron in the same excited state, it can stimulate the electron to emit energy in the form of another photon.  As a result, the second photon would vibrate in the same frequency and in the same direction as the first photon.  The stimulated emission is multiplied by a pair of mirrors at each end of the lasing medium.  Photons of a certain wavelength and direction are reflected off the mirrors and travel back and forth through the lasing medium.  They then hit other atoms with electrons in the excited state, causing yet more photons to be released with the same frequency.  The mirror at one end is “half-silvered,” meaning it lets some light through and reflects some light.  The light (photons) that are let through the mirror are what makes laser light.

Laser light is very different from normal light because of stimulated emission.  This gives lasers the following properties that normal light does not contain:

1. The light is monochromatic, meaning it contains on specific wavelength of light.

2. The light is coherent, meaning that it is organized because the photons all have waves that start in unison.

3. The light is directional, meaning that it is a very tight beam, very strong, and very concentrated.

Types of Lasers

     There are many different types of lasers used today, and are normally classified by the lasing medium, which can be a solid, gas, liquid, or semiconductor.  Solid-state lasers have a solid matrix as their lasing medium, and an example would be a ruby or “Yag” laser.  Gas lasers primarily output red light, and helium or helium-neon are the most common types.  Excimer lasers use reactive gases mixed with inert gases as the lasing medium, which normally produces light in the ultraviolet range.  Dye lasers use complex organic dyes in a liquid suspension as the lasing medium, and the wavelength can be tuned, or changed.  Semiconductor lasers are not solid-state lasers and use very low power, and can be found in such appliances as CD players.  Below is a table of lasing mediums that we use and their wavelengths and colors they produce.

Laser Show Effects

     Laser effects for light shows can be divided into two main categories, beam effects and screen effects.  Beam effects are created by laser beams traveling in the air towards or over the viewers.  There are two types of beam effects, static beams and dynamic beams.  Static beams are beams that do not move but turn on and off, and may use mirrors to reflect the light.  These are generated by beam table and can be the most dangerous type of laser effect.  Dynamic beams move, rather than turn on and off.  They are generated by X-Y scanning systems, and include many different types of effects.  Examples of beam effects can be seen below.

Photographs courtesy of http://www.laserist.org/Laserist/Stuttgart/walsh_mr.jpg and http://www.goldmodel.net/laser.JPG

Screen effects are projected laser effects that require a surface to be projected onto in order to make them visible.  They could be projected onto screens, planetarium domes, buildings, bill boards, and clouds.  Examples of different types of screen effects are graphics, animations, cycloids, abstracts, lumia, and many other projected optical effects.  Photographs of screen effects can be seen below.

Photographs courtesy of Pangolin Laser Systems and http://www.laserist.org/Laserist/Stuttgart/walsh_mr.jpg

Photograph courtesy of http://www.no1-laser-light-show-equipment-rental.com/lumia.gif

     Now that you understand what lasers are and how they work, how do we actually synchronize our lasers, music, and fireworks?  We use computers to pre-program and edit the shows before the performances.  The show is also choreographed to digitally edited music which is played on a high power sound system.  We hope that with understanding how we perform our shows, our audience will be assured of satisfaction!

To see Alison's resume please click here.

This page is not that of a real company but is for a chemistry assignment for General Chemistry 140 at Monmouth College