A laser study bench. This laser is green and about 592nm in laser wavelength. We can see blue laser from about 470nm up to near infrared lasers at about 725nm. All the colors we see are basically between these wavelengths of light. Red is 632.8nm. Anything above 750nm or below 450nm, is invisible to our eyesight. Laser diodes used in laser jammers are 904nm, higher in wavelength than our visual capabilities.

Laser light is very different from normal light. Laser light has the following properties: The light released is monochromatic. It contains one specific wavelength of light (one specific color). The wavelength of light is determined by the amount of energy released when the electron drops to a lower orbit. The light released is coherent. The best laser jammers today detect and block laser guns used today

It is “organized” -- each photon moves in step with the others. This means that all of the photons have wave fronts that launch in unison. The light is very directional. A laser light has a very tight beam and is very strong and concentrated. A flashlight, on the other hand, releases light in many directions, and the light is very weak and diffuse. To make these three properties occur takes something called stimulated emission.

This does not occur in your ordinary flashlight -- in a flashlight, all of the atoms release their photons randomly. In stimulated emission, photon emission is organized. The photon that any atom releases has a certain wavelength that is dependent on the energy difference between the excited state and the ground state. If this photon (possessing a certain energy and phase) should encounter another atom that has an electron in the same excited state, stimulated emission can occur.

The first photon can stimulate or induce atomic emission such that the subsequent emitted photon (from the second atom) vibrates with the same frequency and direction as the incoming photon. The other key to a laser is a pair of mirrors, one at each end of the lasing medium. Photons, with a very specific wavelength and phase, reflect off the mirrors to travel back and forth through the lasing medium. In the process, they stimulate other electrons to make the downward energy jump and can cause the emission of more photons of the same wavelength and phase. A cascade effect occurs, and soon we have propagated many, many photons of the same wavelength and phase. The mirror at one end of the laser is "half-silvered," meaning it reflects some light and lets some light through. The light that makes it through is the laser light.

Types of Lasers: There are many different types of lasers. The laser medium can be a solid, gas, liquid or semiconductor. Lasers are commonly designated by the type of lasing material employed: Solid-state lasers have lasing material distributed in a solid matrix (such as the ruby or neodymium:yttrium-aluminum garnet "Yag" lasers). The neodymium-Yag laser emits infrared light at 1,064 nanometers (nm).

A nanometer is 1x10-9 meters. (Solid state lasers are the type used in laser jammers) Gas lasers (helium and helium-neon, HeNe, are the most common gas lasers) have a primary output of visible red light. CO2 lasers emit energy in the far-infrared, and are used for cutting hard materials. Excimer lasers (the name is derived from the terms excited and dimers) use reactive gases, such as chlorine and fluorine, mixed with inert gases such as argon, krypton or xenon. When electrically stimulated, a pseudo molecule (dimer) is produced.

When lased, the dimer produces light in the ultraviolet range. Dye lasers use complex organic dyes, such as rhodamine 6G, in liquid solution or suspension as lasing media. They are tunable over a broad range of wavelengths. Semiconductor lasers, sometimes called laser diodes, are solid-state lasers; as they are packaged very small to work on PC boards used in electrincs.

These electronic devices are generally very small and use low power. They may be built into larger arrays, such as the writing source in some laser printers, CD players and laser detection and jamming devices. Conventional lasers are gas tube lasers, which look like a long flashlight, typically in a glass enclosure. This Laser Light article is from Matthew Weschler.