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A Light Emitting Diode (LED) is a type of focused light source. A diode is a light emitting circuit found in all lasers. All LED lasers have diodes that only permit light and energy to flow in one direction in a concentrated beam. The lasers cause this energy flow by their manipulation of electrons.
An LED laser is a semi-conductor light source, which means the LED laser light source is formed by bringing two slightly different materials close together to form a positive-negative (PN) junction. The positive side, the anode, is created through an absence of electrons and the corresponding holes from this absence. The negative side, the cathode, contains an influx of electrons. The joining of the electrons into the holes creates the light.
This joining of electrons in holes creates no light feedback, which is commonly caused by stray electrons. This is a problem with laser diodes as it causes multiple modes of light emission, which can affect the width of the beam. Since the LED laser only has one mode, as each electron from the cathode has its corresponding hole in the anode, no corrective actions need to be taken, as typical with other types of lasers.
The first LED lasers emitted a low intensity red light because the photons released by the diodes electrons were extremely close to infrared light. LED lasers have since evolved into most wavelengths on the visible and non-visible spectra, meaning their lenses can be manipulated to visible colors. Modern LED lasers are available in infrared and ultraviolet light as well.
LED lasers can be made of a compound called aluminum gallium indium phosphide to create the semi-conductor circuit and the PN junction. These materials create red, yellow and orange LEDs. Different variations of the elements in each compound create variations in the color. A different materiel, indium gallium nitride, creates green, blue and white LEDs.
LED lasers are more cost-effective to produce as well as provide power to. A typical LED laser requires 30-60 milliwatts of energy to produce light, much less than other lasers. Also, the spectrum of visible light of an LED laser is much greater than that of a laser due to its wider range of wavelength frequencies.
The voltage required for an LED is generally quite low compared to other forms of light devices. A single indicator LED laser requires two to four volts of electricity and emits 1-50 amps of light compared to laser diodes, which require four to six volts of energy for the same amperage. LED lasers used for household and municipal lights require the same amount of volts of electricity as incandescent lighting systems, but can provide several thousand amps of light.
The lower amount of energy required for LED lasers makes them ideal to be run on direct current batteries. These lower energy LED lasers can be used for smaller beams, such as flashlights and book lights. They provide adequate lighting as well as a longer lamp life due to the lower voltage required.
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