Laser diode modules were first created in 1962 and have since become a fundamental part of modern technology. They are commonly found in compact disc drives, DVD drives, projectors, and laser pointers. They are also frequently used in medical procedures and in industrial settings. Laser diode modules consist of a laser diode, which is what produces the actual laser beam, and the module, which holds and protects the diode. Laser diode modules are much more common and practical than conventional gas lasers because of their small size, low cost, minimal power usage, and narrow beam.
Laser diode modules produce a laser beam when current flows through the diode. The term "laser" is actually an acronym that means "light amplification by stimulated emission of radiation". Lasers produce a focused beam of light that travels in a straight line and does not spread out, which is why they are so useful for many applications. Unlike white light, which is a mixture of many different colors, lasers usually produce light of only one color.
One of the most common uses of lasers is in compact disc and DVD drives. In CD and DVD drives, the laser diode modules are controlled by the computer to "read" or "write" from a CD or DVD. When writing to a CD or DVD, the laser darkens the dye in the CD or DVD, which allows the computer to store information from the media in the form of 1's and 0's. The computer can later read this information using the laser. This process makes it possible to store large amounts of information in a small amount of space on an inexpensive medium, and it has made computing much more practical.
Laser diode modules are also often used in medical procedures and for industrial purposes. The laser beams are so compact that there is a large amount of energy in a small amount of space. This means powerful lasers can be used to burn things. This is used in the medical world for laser hair removal and eye surgery and in the industrial world for cutting and burning things. Lasers used for these purposes usually have a power rating of at least 1 watt; for comparison, a handheld red laser pointer usually has a power rating of around 5 milliwatts.
Typically, the lasers diode modules found in CD and DVD drives have a wavelength of 650 nanometers (nm). This produces a bright red laser beam that is similar to those seen in handheld red laser pointers. Other common wavelengths include 532 nm, which is bright green and is typically found in consumer laser pointers, and 405 nm, which is found in Blu-ray™ players.
Infrared laser diode modules produce light in the infrared spectrum and not visible to the human eye. They are more common in medical and industrial settings, because they are typically much more powerful than lasers in the visible spectrum and are generally more cost effective than visible lasers. All lasers are dangerous and should be handled carefully, but infrared lasers are particularly dangerous because they are not visible to the human eye and can easily inadvertently damage someone's vision.