Small lasers, such as those in CD and DVD players and laser pointers, use electronic circuits to provide electric current to diodes, which serves as the pump. Carbon dioxide lasers are pumped with electrical discharges to excite their electrons. Excimer lasers get their energy from chemical reactions. [3] X Research source Lasers built around crystals or glasses use strong light sources such as arc or flash lamps. [4] X Research source
Semiconductors made of materials such as gallium arsenide, aluminum gallium arsenide, or indium gallium arsenide. Crystals such as the ruby cylinder used in the Hughes Laboratories laser. Sapphire and garnet have also been used, as have fibers of optical glass. These glasses and crystals are treated with ions of rare earth elements Ceramics, which have also been treated with rare earth ions. Liquids, usually dyes, although an infrared laser was produced by using a gin and tonic as the gain medium. Gelatin dessert (Jell-O) has also been used successfully as a gain medium. [6] X Research source Gases, such as carbon dioxide, nitrogen, mercury vapor, or a helium-neon mixture. [7] X Research source Chemical reactions. Electron beams. Nuclear materials. A uranium laser was first produced in November, 1960, six months after the first ruby laser. [8] X Research source
The simplest resonator setup, the linear resonator, uses two mirrors placed at opposite sides of the laser chamber. It produces a single output beam. A more complicated setup, the ring resonator, uses three or more mirrors. It may create a single beam, with the help of an optical isolator, or multiple beams.
A driver circuit. (This is sometimes sold separately from the other components. ) Look for a driver circuit that lets you adjust the current. A laser diode. An adjustable lens of either glass or plastic. Typically, the diode and lens are packaged together in a small tube. (These components are sometimes sold separately from the driver circuit. )
You can also design your own driver circuit, if you have the electronics skills to do so. The LM317 driver circuit provides a good template for designing your own. Be sure to use a resistor-capacitor (RC) circuit to protect the power output from spikes. [10] X Research source Once you have assembled the driver circuit, you can test it by connecting it to a light-emitting diode (LED). If the LED doesn’t light up right away, adjust the potentiometer. If that doesn’t fix the problem, recheck the circuit to see that everything is correctly connected.
While a more powerful beam from the diode will produce a more powerful beam, the additional current needed to generate that beam will burn the diode out faster.
Once you’ve adjusted the lens this far, place a match in line with the beam and adjust the lens until you see the match head start to smoke. You can also try to pop balloons or burn holes in paper.
A DVD writer has a red diode with a wavelength of 650 nanometers (nm). A Blu-Ray writer has a blue diode with a wavelength of 405 nm. The DVD writer needs to be functional enough to write discs, although not necessarily successfully. (In other words, its diode needs to be functional. ) Do not substitute a DVD reader, CD writer, or CD reader for the DVD writer. A DVD reader has a red diode, but not as powerful as a DVD writer. The CD writer’s diode is powerful enough, but emits light in the infrared range, tempting you to look for a beam you can’t see.
Once you’ve separated the drive, you’ll see a pair of metal rails held in place with screws. These support the laser assembly. When you unscrew the rails, you can remove them and take out the laser assembly. The diode will be smaller than a penny. It has three metal pins and may be encased in a metal jacket, with or without a protective transparent window, or it may be exposed. You’ll have to pry the diode out of the laser assembly. You may find it easier to remove the heat sink from the assembly before trying to extract the diode. If you have an anti-static wrist band, use it while removing the diode. Handle the diode with care, more so if it is an exposed diode. You may want to have an anti-static container to put the diode in until you can assemble your laser.
Use a magnifying glass as a focuser. You’ll have to move the glass around to find the right spot to produce a laser beam, and you’ll have to do this each time you use your laser. Get a low-powered laser diode, such as 5 mW, lens tube assembly and substitute your DVD writer diode for the assembly’s diode.
Hold the diode with the pins pointing toward you, rotated so the pinheads make a triangle that points to the right. On both diodes, the pin at the top is the positive pin. On the red DVD writer diode, the centermost pin, which forms the apex of the triangle, is the negative pin. On the blue Blu-Ray writer diode, the bottom pin is the negative pin.
