How does a laser pointer work?
Ever wondered how does a laser pointer work? Albeit its compact size, there are a lot of things going on behind the scenes to produce the tiny laser beam from your pointer. If you’re curious about what goes on inside your trusty pocket laser pointer, or just lasers in general, keep on reading!
What is a laser pointer?
The word “LASER” itself is an acronym of Light Amplification by Stimulated Emission of Radiation. Only a handful of modern lasers use light amplification but the name stuck even for lasers with one color or wavelength (monochromatic laser).
In a nutshell, a laser pointer is a device typically used to highlight something important. It works by powering a laser diode with an energy source which will then emit a coherent low-powered beam of visible light.
The uses for a laser pointer vary; it can be used during a presentation, to point out stars, for science experiments, and more. Laser pointers are available in various colors, sizes, and prices as well. For instance, the pocket laser pointer that we’re familiar with emits a red laser and is quite affordable. On the other hand, laser pointers used for stargazing are usually green and have higher wattage so we can use it during the night. Other laser colors include blue, violet, and yellow.
When was the laser pointer invented?
Affordable, pocket-sized laser pointers that we know today can be dated back to the 1980s. However, the concept of the laser can be dated back to the late 1950s. Researchers at Bell Labs produced a theory to create lasers in 1958. Two years later, Hughes Aircraft built the very first laser, using rubies, light, and mirrors to produce the beam. Then, in 1962, the first semiconductor laser was created. Also known as diode lasers, this technology made laser pointers more affordable and accessible to the mass market.
Cheap green laser pointers may not filter out any unconverted infrared laser light. If this invisible infrared laser light shines in your eye, you won’t be able to see it, so you don't blink or move, causing permanent damage to your eyes.
How does a laser pointer work?
Laser pointers have three important components: lasing medium, energy source, and a resonator. The lasing medium refers to a material that can be powered by an energy source, which can be in the form of light or electricity. Light mediums can be in the form of gas, liquid, or minerals like the rubies used in the first laser pointer.
Once the laser medium is powered or pumped, it will release the energy in the form of monochromatic radiation. The function of the resonator then comes to play; it holds the energy and builds it up before it releases the energy. The resonator is made up of two mirrors located at each end of the lasing medium. One would reflect the light back to the medium and the other would divide it between the medium and the chamber’s exit.
The resonator is also responsible for aligning the light in one direction, which causes coherency of the laser beam. The alignment of the light is done through the bouncing of the light that goes back and forth between the two mirrors.
Semiconductor lasers or diode lasers produce light when electricity passes through them in a single direction. Laser diodes usually contain a circuit board, optics, and a case. The semiconductor is usually made from compounds like aluminum, arsenic, phosphorus, gallium, or indium. Traces of tantalum and gold can also be found.
Refer to the video below for more information on how the laser works.
Laser pointer’s power ratings
As a safety measure, laser pointers are classified into four main classes and subclasses based on their wavelength and maximum output power. The classes are categorized based on how damaging the laser can be to the naked eye, with 1 being no danger to 4 being severely dangerous for the eyes and skin. The following is the complete list of the laser classifications:
Safe without optics or viewing aids
Visible laser; safe when accidentally exposed
Visible laser; safe when accidentally exposed without optics or viewing aids
Unsafe; low risk
Dangerous but safe to view the reflection of radiation on surfaces
Dangerous; unsafe to view the reflection of radiation on surfaces; fire risk
Some low-quality laser pointers can be wrongly classified. They could possess higher power than they’re supposed to, which can be dangerous if wrongly used. For example, the National Institute of Standards and Technology conducted tests on laser pointers labeled as Class IIIa or 3R in 2013. The results showed that about half of the laser pointers emitted power at twice the Class limit. Hence, instead of Class IIIa, the correct classification should be Class IIIb, which is more dangerous than Class IIIa.
The highest measured power output was 66.5 milliwatts; more than 10 times the limit. Green laser light is generated from an infrared laser beam, which should be confined within the laser housing. However, more than 75% of the laser pointers tested were found to emit infrared light in more than the limit.
Why you don’t want to use a cheap green laser pointer
If you’re hesitant on which type of laser pointer to choose, it’s best to avoid cheap green lasers. Green lasers often use an invisible infrared laser that is then converted into visible green light by clever optical materials. Cheap green laser pointers may not filter out any unconverted infrared laser light. If this invisible infrared laser light shines in your eye, you won’t be able to see it, so you don't blink or move, causing permanent damage to your eyes.
This can be further explained scientifically through the concept of infrared diodes. Infrared diode lasers are normally cheaper, which led to the creation of infrared-pumped green, violet, and blue diode laser pointers with double frequency. With infrared (IR) diode laser modules of up to 1000 mW, those laser pointers may have visible power up to 300 mW.
Filtering invisible infrared light in the laser beam is highly challenging. Doing so can contribute to a higher heat level that would be hard to distribute within a pocket-sized laser pointer. The infrared then is left as particles in cheaper high-power laser pointers because of the difficulty to filter the infrared. This invisible infrared component in these cheap green laser pointers can be a source of an extra potential hazard when pointed at nearby objects and people.
How to safely use your pointer
Now you have already known the answer for the question "how does a laser pointer work?". In addition, when using a laser pointer, no matter how low or high the power of the light is, you should always maintain the safety protocols. Here are some important things to always keep in mind when using a laser pointer:
- Never direct your laser pointer towards someone’s eyes
- Never point the laser beam directly towards an animal
- Never look directly into the laser beam
- Never aim your laser pointer towards any kinds of vehicles
- Take note of reflective surfaces and avoid them
- Avoid prolonged contact between the laser and the skin
- Wear safety goggles and gloves when using high-powered lasers
Check out these quality laser goggles that you may need to protect your eyes: