Wednesday, November 27, 2019

Laser Diode, Function, Circuit and Symbol



The photo above shows a small laser diode that is widely available on the market at a low price. The red wire is connected to the positive and the blue wire is connected to the negative. Usually the maximum voltage is around 4.5 volts.

Laser diode is semiconductor diode device, and it is about similar to light-emitting diodes (LEDs). Laser diode can directly convert electrical energy into light.

LASER stands for Light Amplification by Stimulated Emission of Radiation which can be interpreted as light produced from stimulated photon emissions. The light produced has the same phase, coherence, and wavelength.

Laser light radiates in a straight line, does not spread like ordinary light. So that the energy is focused and causes the laser light to contain high heat. Because the light is radiated straight and the heat is high, these characteristic are usually used for various purposes in applying laser technology.




YouTube video of green laser that light precious stone, crystal vessels, cut thread, and lit match.

The type of semiconductor material determines the wavelength of the emitted light, which in laser diodes currently ranges from a fairly broad spectrum from infrared (IR) to ultra violet (UV). Laser diode functions include laser pointer, laser printer, measuring distance, straightness and level, viewfinder, optical fiber communication, barcode reader, CD / DVD / Blu-ray disc reading / recording, engraver, laser cutter, surgical instrument, laser hair removal, tattoo removal, disco lights, magic tricks, laser beam shows and more. With the use of phosphorus as in white LEDs, laser diodes can be used for general lighting, remote spotlights, and others.


The laser diode symbol used in the circuit scheme is as shown above. Sometimes equipped with a circle around the diode. The pin connections in the circuit are the same as the rectifier diode, ie the anode pin (A) is connected to positive, and the cathode pin (C) is connected to negative.



The above scheme is the basic principle of a diode (LD) laser circuit. Batteries (B) are usually 4.5 volts or depending on the diode specifications.


The photo above is a diode laser with 3 pins. Usually the center pin is the body, used to strengthen the mounting. Pin connections can differ depending on the manufacturer.


Keychain with LED flashlight and laser diode pointer.


The above photo show all components of a small pointer after disassembly by pulling the front cover out. Then all components can be pulled out of the front end easily. Two buttons are pointed by red arrows. Those buttons need to be pressed when pulling electronic components out.



The above photo is a red light laser module power 5 milliwatts 5 volts.


The above photo is a box of laser pointer FGH-303, with a voltage of 3.7 volts and power less than 2000 mW, wavelength 532 nm (green). With this great power, it can lit a match head from a distance of about 7 cm.


This green laser focus can be adjusted, if the lens is closer to the diode, the beam will be more straight, and the hottest point about 7 cm from the snout.


If the lens is extended away from the laser diode, the focus point is about 8 cm and becomes hotter. Furthermore, the beam will spread and become more like a flashlight, not straight.






YouTube video about laser used for shooting practice without live ammunition or dry fire shooting.


Book about how to make various models of laser pistols that can also be used as laser pointers can be obtained at Amazon. But currently only available in certain countries.

Please use laser diode wisely. Do not be directed to the eye directly or the reflection, because it can create permanent damage to the eye. Do not aim at the vehicle. Do not aim at the sky, because low-power laser light can be seen and reach a distance of several kilometers that can interfere with flight.


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