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Laser Diode Radiation Danger

Laser diodes are in many items used in home, classroom and laboratory settings. While their rate of energy output varies according to product use, all laser diodes pose potential risk when used irresponsibly. To understand the potential radiation risks of laser diodes it is important to understand their construction and classification for safe use.

  1. What Are Laser Diodes?

    • Laser diodes are used to produce low level laser energy that can be used for a variety of purposes. Most commonly, they can be found in laser pointers, used in business to highlight information in charts and on screens during visual presentations. They are also used in electronic devices that read discs to play audio and video content. In the medical field, laser diodes are used in light therapy as well as other medical equipment.

    How Laser Diodes Work

    • Laser diodes use microscopic chips of gallium-arsenide or other semiconductors to generate light within a compact package. The laser ray is created by the energy variance between electrons within the semiconductors. Common laser diodes like the ones used in pointers and electronic devices have a maximum output of between three and five megawatts of optical power. Three primary types of laser diodes are used: homojunction, heterojunction and pulsed laser diodes. Typically, laser diodes are extremely sensitive. They must receive very limited amounts of energy to avoid burning out; they should be handled very carefully to avoid damaging their construction.

    FDA's Low Level Danger Categories

    • The FDA's Center for Devices and Radiological Health (CDRH) has classified laser diodes into six health categories based on their potential damage to the eye. These categories are used to classify diodes for labeling purposes to ensure users have potential hazard information available to them when using the instrument. The first three classes--1, 2, and 2a--are for lasers that have very low output. Users are cautioned against looking directly into the beam for more than 1,000 seconds. Typically these lasers pose minimal risk of damage due to low energy output and casing or packaging that prevents the user from coming into any visual or physical contact with damaging elements of the laser.

    FDA's High Level Danger Categories

    • The last three categories issued by the CDRH address laser diodes in higher output levels. Class 3 (a) warns against looking into beams or using magnifying optics with lasers up to five megawatts in output. Class 3 (b) addresses laser diodes up to 500 megawatts, classifying them as a dangerous with visible or invisible laser radiation damage with direct exposure. Class 4 indicates high power lasers with output of more than 500 megawatts. These diodes possess visible or invisible laser radiation and users should avoid eye or skin exposure to the beam.

    Children and Laser Diode Warnings

    • The FDA issued direct warnings in 1997 on the potential for eye injury to children from handheld laser pointers. After reports of eye injuries in young children from laser diodes in pointers and toys and other laser products, the Academy of Ophthalmology upgraded cautions in 1998 indicating laser diodes should be kept away from children. Reports of misuse of laser diodes have included children pointing lasers into the eyes of other children during play. The impact of radiation danger will vary according to the laser's wavelength, output power and distance. At a distance greater than 10 feet, most diodes will not pose immediate danger. Visible and near-infrared wavelengths can be absorbed by the retina, leading to what can be lasting ocular injury.

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