Lasers are like tiny light sabers, but instead of wielding them with your hands, you use science to control them. At the heart of every laser is a process called stimulated emission. It’s kind of like having a party where everyone is excited and talking at the same time, but instead of sound waves, we’re dealing with light waves.
The first step in creating a laser is to find a material that is capable of amplifying light, also known as a gain medium. This can be a crystal, a gas, or even a liquid. The gain medium is placed inside a tube or cavity, and the walls of the tube are highly reflective.
Next, we need to pump energy into the gain medium. This can be done with electricity, light, or heat. This process excites the atoms in the gain medium and gets them all riled up and ready to emit light.
Now comes the fun part: stimulated emission. When a light wave passes through the gain medium, it can stimulate the excited atoms to emit their own light waves. These waves are all in sync and have the same frequency, which is what gives lasers their unique properties.
The light waves bounce back and forth between the reflective walls of the tube, passing through the gain medium over and over again. Each time they pass through, more and more atoms are stimulated to emit their own light waves, amplifying the laser beam.
Finally, a tiny opening in the tube, called the aperture, allows the laser beam to escape and be directed towards its target. And just like that, you have a laser beam that is highly concentrated, monochromatic (meaning it has a single color), and coherent (meaning the waves are all in sync).
So the next time you’re using a laser pointer to entertain your cat or cutting through steel with a high-powered industrial laser, just remember: it’s all thanks to the magic of stimulated emission.
Projects to Try at Home
Build a laser pointer
To build a laser pointer, you will need the following supplies:
- A laser diode: This is the component that produces the laser beam. You can purchase laser diodes online or at electronics stores.
- A battery: The laser diode will need a power source. You can use a AA or AAA battery, depending on the laser diode you are using.
- A battery holder: This is a plastic or metal case that holds the battery in place.
- A momentary push button switch: This is a small button that allows you to turn the laser diode on and off.
- Wire: You will need wire to connect the components together.
- Soldering iron and solder: You will need these tools to attach the components together.
To assemble the laser pointer, follow these steps:
- Connect the positive terminal of the battery to one end of the push button switch.
- Connect the other end of the push button switch to the positive terminal of the laser diode.
- Connect the negative terminal of the laser diode to the negative terminal of the battery.
- Test the laser pointer by pressing the push button switch. The laser diode should turn on and project a small, bright dot of light.
Experiment with laser-cut paper
To experiment with laser-cut paper, you will need the following supplies:
- Pre-cut paper shapes: These can be purchased at craft stores or online.
- A laser cutter: This is a machine that uses a laser to cut and shape materials. You can find laser cutters at makerspaces, schools, or universities, or you can hire a company to do the cutting for you.
To use the laser cutter, follow these steps:
- Load the paper shapes into the laser cutter.
- Use the laser cutter’s software to specify the shape and size of the cuts you want to make.
- Press the “start” button to begin the cutting process. The laser cutter will follow the instructions you entered in the software to cut the paper shapes.
Make a hologram
To make a hologram, you will need the following supplies:
- A CD case
- A laser pointer
- A piece of transparency film
- Scissors
- Glue
To make the hologram, follow these steps:
- Cut a small square out of the transparency film and glue it to the inside of the CD case.
- Point the laser pointer at the transparency film and turn it on.
- Move the CD case around to see the hologram. The laser light will be reflected off the film and create a three-dimensional image.
Build a fiber optic communication system
To build a fiber optic communication system, you will need the following supplies:
- A laser pointer
- Two small mirrors
- Fiber optic cables
- A sheet of cardboard or foam board
- Glue or tape
To build the communication system, follow these steps:
- Cut a small hole in the cardboard or foam board.
- Glue or tape one of the mirrors to the hole.
- Glue or tape the other mirror to the end of one of the fiber optic cables.
- Point the laser pointer at the first mirror and turn it on.
- Observe the laser beam as it is transmitted through
To Learn More
There are many resources available online and in print that can help you learn more about lasers and how they work. Here are a few suggestions to get you started:
Websites: There are many websites that offer detailed explanations and interactive simulations of how lasers work. Some examples include How Stuff Works (https://science.howstuffworks.com/laser.htm).
Books: There are several books that provide in-depth explanations of the physics behind lasers and how they work. Some examples include “Laser Fundamentals” by William T. Silfvast and “Laser Physics” by Stephen Bishop.
Scientific journals: Many scientific journals publish research articles and review articles on lasers and their applications. Some examples include “Optics Letters” and “Applied Physics B: Lasers and Optics.”
Online courses: There are also several online courses and MOOCs (massive open online courses) available that cover the basics of laser physics and how lasers work. These courses often include interactive simulations, video lectures, and quizzes to help you learn the material.
By exploring these resources, you can gain a deeper understanding of lasers and how they work.
Light sabers may be the stuff of sci-fi legend, but lasers are very much a real-world technology. While light sabers can cut through anything and deflect blaster bolts, lasers are limited to concentrated beams of light that can be used for cutting, welding, data storage, and long distance communication. No deflecting blaster bolts with lasers, unfortunately. But hey, we can still dream of wielding our own light sabers one day!