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How do Lasers Work

How do Lasers Work

How do Lasers Work

How do Lasers Work

How do Lasers work? Good question, the answer involves a fairly complex understanding of semiconducting Physics as well as some basic optics. We use Lasers almost everyday in our modern lives, yet they still retain a bit of mystery as you find it very hard to get a decent explanation of how they work on the internet. Hopefully this page will clear that up.

The word Laser is an acronym for Light Amplification by the Stimulated Emission of Radiation (LASER). At the heart of a Laser is the semiconducting diode, this is a material that conducts electricity under certain circumstances but will not conduct electricity under other circumstances.

LEDs and Lasers actually work on very similar principles, the difference being that a laser concentrates the light that is produced into a single beam of light that as the same wavelength, color and direction, hence its power and distance of travel.

I will be explaining how a key chain type Laser works, these are the small handheld ones that you can attach to your key rings, I’m sure you have seen them before (however they all work on the same basic principles) –

How do Lasers Work - A typical Key chain Laser

How do Lasers Work - A typical Key chain Laser


First, i have rendered a cut through the laser, lets look at the internal components of a typical key chain Laser –

How do Lasers Work -  The parts of a Laser

How do Lasers Work - Laser Parts


On the left we have the collimating lens housing. The collimating lens focuses the laser beam into a thin strong pulse of photons.

Next is the Laser Diode, this is where the laser light is actually produced, more about that later on.

How do Lasers work – The photodiode

Next to that we have the photo diode, the photo diode regulates the voltage to the Laser diode so it does not go above a certain predetermined factory-set power rating (this is the part you “damage” if you want your laser to be more powerful than it was designed to be 😉 )

Next is a simple switch which completes the circuit when depressed, above that is the button and then the batteries, all fairly self explanatory.

How do Laser Diodes Work

The main component of interest to us is the Laser Diode, this is the source of the laser light, so now we’ll see how it works.

When we zoom in towards the Laser diode with most of the other Laser components removed it looks like this while on its circuit-board –


How do Lasers Work -  Laser diode on circuitboard

How do Lasers Work - Laser diode on circuit board

 How Lasers Work Page 2