How Lasers Work – A Complete Guide

This guide is intended for those new to portable laser technology and covers basic terminology as well as advice for buying a laser pointer or any other laser technology device. Lasers are awesome devices that while not often brought up in conversations, are a part of our everyday lives even without you realizing it.

When was the last time you watched a Blu-Ray DVD? At the core of a Blu-Ray player is a 405nm violet laser diode. In the days of CD/DVD players, 650nm – 660nm laser diodes were used. Portable lasers, like the ones we offer, are commonly found in medical and laboratory environments, used in military operations, fitted into industrial and commercial machinery, and are loved by laser enthusiasts throughout the world.

A Brief Overview

LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.

If you want a definition of what a laser really is, then this is a good one; “a device generates an intense beam of coherent monochromatic light (or other electromagnetic radiation) by stimulated emission of photons from excited atoms or molecules“.

As the explanation of the principles behind how lasers work can get quite complex, we will not go over this in our buying guide.

The fundamentals of laser technology were first theorized by Albert Einstein in 1907, however, the first working laser did not appear until 1960 when Theodore H. Maiman operated the first functioning laser at Hughes Research Laboratories in California, USA.

Its been more than half a century and laser technology has changed from being a large piece of machinery only found in laboratories to a tiny laser diode that is widely available. As mentioned earlier, lasers have truly assimilated into society and have improved our lives on many levels due to its impressive range of applications.

You can find lasers being used in drilling and cutting, alignment and guidance, and in surgery; the optical properties are exploited in holography, reading bar-codes, and in recording and playing compact discs and DVDs.

More importantly, for the purpose of this guide, portable laser technology has become increasingly popular as battery operated lasers you can hold in your hands are now available in a variety of wavelengths and power outputs unimaginable just several years back.

These pen-styled lasers are commonly used as astronomy laser pointers in star gazing (or attached to a telescope), in the classroom as presentation laser pointers, in universities and medical buildings for research, in manufacturing facilities for cutting, alignment, and sorting, in night clubs and bars as laser light shows and counterfeit detection, and much more.

This guide will introduce you to basic terminology, laser characteristics that’s important to buying a laser pointer, an overview of our product lines, some clarification about visible lasers that maybe falsely advertised elsewhere, and ultimately which type of laser pointer is most suitable for you.

Before getting started, run to the bathroom now and grab a quick snack and drink before reading this guide. We spent many hours working on this guide, so enjoy!

Basic Terminologies

This section covers basic terminology commonly used in portable laser technology including wavelength, spectral sensitivity, power output, beam diameter, and beam divergence. An understanding of these terms will give you a better perspective on lasers as well as the type of laser most suitable for you.

Wavelength

If you’re confused about wavelength and what all the numbers ending with “nm” stand for, don’t be. Some really smart people really long ago discovered that light exhibits both particle and wave properties, or have particle-wave duality. Looking at the wave side of things, wavelength is just the length of a light wave before it repeats itself measured in nanometers, or one billionth of a meter.

The diagram below is a representation of what a wave looks like as well as the various types of waves there are in the electromagnetic spectrum. The type of wave is designated by a wave’s wavelength.

waves

For our purposes, it’s only important to understand that each color we see is associated with a range of wavelengths.

For instance, any light with wavelengths between 495nm – 570nm is green. Each specific wavelength, such as laser light emitted by our 532nm green laser pointer, is a specific shade of green. As visible light lasers are only available in very select wavelengths, you’ll see the same numbers repeat itself over and over again on our website.

An interesting topic arises when asking if there is a best wavelength for visible lasers, particularly for the wavelengths of lasers we carry. While this is a subjective question, green lasers do appear brighter, are more clearly visible in darkness compared to other lasers we carry, and is the best selling type of laser globally.

Spectral Sensitivity

So, we’ve clarified that the reason that green lasers are more easily viewable to us is that our eyes are more sensitive to this color.

While green lasers are not physically brighter or more powerful, it “appears” so. I receive many messages about ranking lasers in order of brightness based on our eye’s sensitivity. Although this is not perfectly accurate as there are many other variables involved, after green, our eyes are more sensitive to blue compared to red or violet in darkness. Our eye’s sensitivity to red and violet are comparable in darkness.

In daylight conditions, green is still the clear winner with red actually more apparent compared to blue with violet being the least desirable.

In this section, we discovered that due to spectral sensitivity, our eyes view different wavelengths differently making some laser light appear brighter. In the next section, I’ll go over power output, the real factor determining brightness.

Power Output

The power output is the amount of power or energy a laser emits. While most lasers we carry can be measured in milliWatts (mW), or one thousandth of a Watt, our higher powered models are measured in Watts (W). Generally speaking, the higher the power output, the brighter and more capable a laser is of burning.

This assumption is true if you compare lasers of the same wavelength and model. However, this assumption quickly falls apart when different wavelengths and models are compared.

Let’s start this discussion by comparing 100mW and 300mW green lasers. Our general assumption that the higher power output laser is brighter and more capable stands true. That is, the 300mW green laser is much brighter and more capable and faster at completing an action such as cutting electrical tape or lighting a match. Things become tricky when you start comparing lasers of different wavelengths and models.

For example, if we compare a 100mW green laser with a 300mW violet laser, the green laser will be much brighter due to our eye’s sensitivity to green (discussed in our section onspectral sensitivity). However, as the 300mW violet laser has higher power output, it’s the more capable laser. This is especially true for our handheld and portable lasers due to the focus adjustable feature. I will go over this feature later in this guide.

To complicate things further, let’s compare our 80mW green laser pointer to our 80mW violet laser pointer. As you may have guessed, the 80mW green laser pointer is much brighter. However, did you know that it’s also much more capable? This leads us to two other terms you should get yourself familiar with, beam diameter and beam divergence.

Beam Diameter

The beam diameter is defined as the diameter of a laser beam. It is measured at aperture, and you will usually find it measuredin millimeters (mm). Although this seems like a specification we can ignore, the beam diameter plays an important role in brightness and capability. Have you ever tried focusing the sun’s energy with a magnifying glass? The smaller you’re able to focus the end spot, the more powerful or capable it is of burning.

This is an excellent demonstration of intensity, the energy per area. One Watt of energy delivered over a square-foot is just a lightbulb, however, if you deliver the same Watt of energy in spot the size of a pin-head, it’ll light a cigarette.

Putting intensity into perspective, we can revisit our example of comparing the 80mW green and violet laser pointers. The green laser has a beam diameter of 1.5mm while the violet laser has a beam diameter of 2.5mm. Using the simple formula for calculating the area of a circle, π * r2, we find the area of the green laser beam to be less than half that of the violet laser.

Without going into any more mathematical formulas, we know the intensity of the green laser is higher and is therefore the more productive laser.

Beam Divergence

The beam divergence is defined as the angular measure of the increase in beam diameter, with measured distance from the aperture. It is measured in milli-radians (mRad).

To demonstrate what I mean, if you has a beam divergence of zero, that would indicate that the laser beam doesn’t increase at all in beam diameter. This isn’t possible. Usually, you would say that the lower the mRad, the better. Anywhere between 1-3 mRad is considered okay.

Returning back to the topic of intensity, since a laser always divergences, intensity always decreases with distance. A laser with low beam divergence would mean intensity decreases slower over distance. The result is a longer effective range where the laser is more capable and offers greater beam visibility.

The beam divergence is also an important factor in determining NOHD, the distance from the laser where the intensities and energies fall under maximum permissible exposure (M.P.E) for your eyes. We’ll go over this topic later in this guide.

Visibility

Many sellers advertise lasers using misleading adjectives such as “highly visible” or “most visible laser beam”, however, how visible are these laser beams? If you’ve followed this guide from the beginning, you already know that many factors play a role in this and it’s a combination of these factors that determine true visibility seen by our eyes.

 

Color 5mW 30-50mw 80-100mW 150mW +
Violet No beam Faint beam Faint/nice beam Nice beam
Blue Faint beam Nice beam Awesome beam Wicked beam
Green Faint beam Nice beam Awesome beam Wicked beam
Red No beam Faint beam Nice beam Nice beam

One thing that I get asked often is about the laser beam. It is not viewable under direct sunlight under any circumstance! The darker or duller the weather is, the easier it becomes to see the beam.

This is obviously why it’s most popular to use laser pointers during the night time. Whether your laser pointer is 1 mW or 100 mW, it’ll be visible during the nighttime.

Burning

If you’ve read this far, you’re probably aware that the weaker laser pointers are not capable of burning. Whilst there isn’t a set limit to what power and size you need a laser pointer to be to be capable of burning, I’d say the bare minimum is 100mW. If it isn’t this powerful, then your laser pointer just isn’t going to be powerful enough to burn anything.

If burning is something you want from your laser, then you should opt for a higher power laser pointer. On top of being available in much higher power outputs, the ability to adjust the focus make these series ideal for burning. Additionally, the focus-adjustable lens also turns these lasers into breath-taking laser flashlights.

We’re not going to cover what items a laser can burn and let you explore the possibilities (my favorite is balloons). This is because darker colored objects absorb light whereas lighter colored objects reflect it.

Starting a Fire

Ever wonder if you can start a fire with a laser pointer? Well, the short answer is YES! You’ll need a bit of primer material (such as char cloth or tinder), but with the right technique, our handheld and portable lasers can be great fire starters. Check out this video of us burning coffee grounds!

 

Focus Adjustable Feature

Going back to the topic of intensity, if we can reduce the area of a laser’s end spot, ideally into a pin-point, we can increase intensity making a laser more capable. Some focus-adjustable lens does exactly this by generating a focal point outside the laser.

This feature in addition to the already incredibly high power outputs make these lasers extremely capable, a device that can be potentially dangerous if handled incorrectly. This is more reason to always wear laser safety glasses while handling these lasers.

Remember that the majority of lasers do not have this feature, so it if you’re just looking for a simple laser, you won’t need to worry about this.

 

Direct Diode Lasers vs. DPSS Lasers

This discussion on direct diode compared to diode pump solid state (DPSS) lasers is confined to green lasers.

We’re not going to get into details of how laser diodes work, however, it is important to understand that laser diodes are available in certain wavelengths based on the chemical compound used as the pumping medium. For example, a 445nm blue laser diodes is constructed using Gallium Nitride as the pump medium. Just a couple of years ago, green laser diodes did not exist. Instead, an indirect method of attaining a green laser using semiconductor technology is used to generate the common 532nm green laser pointer.

Inside each 532nm green DPSS laser is actually an 808nm infrared laser diode. This infrared diode is used to pump a neodymium-doped laser crystal to produce 1064nm infrared laser light. This light is then frequency doubled using another crystal, a KTP crystal, where 532nm is finally produced.

This indirect method while capable of accomplishing green laser light is not the most efficient. There is considerable power loss as the light is required to pass through multiple crystal mediums. In fact, a portion of the infrared light is not converted at all.

Additionally, optimal conversions of light through these crystals occur around room temperature. Therefore, based on temperature, there will be power fluctuations. As you may have guessed, a direct diode laser, a laser that does not require several levels of light conversion, is more efficient and stable.

Usually, 515nm / 520nm lasers are direct diode green lasers. Although the 515nm / 520nm lasers are more expensive compared to its 532nm cousin, we do expect prices to fall in the near future as they become produced in bulk for devices such as laser projectors.

Infared Filters

The fact that a portion of infrared light is not converted into 532nm green laser light leads us to another discussion about infrared filters. An infrared filter is a lens that blocks infrared light while allowing light in other wavelengths to pass. The general consensus is that 532nm green DPSS lasers should have an infrared filters attached.

As infrared light is not detectable by the human eye, it does not trigger our natural blink reflex. Green DPSS lasers usually emit both 532nm green light and 808/1064nm infrared light, so the green light will trigger our blink reflex.

However, there will be times when only infrared light is emitted. This may occur during the first couple of seconds of operation during warm-up. Infrared filters are not expensive, however, many laser vendors leave this out because it causes a 10-15% reduction in power.

While we’re on this topic, let’s take a closer looking into issues that may arise with cheap lasers.

Avoid Cheap Laser Pointers

A quick search on Google will reveal hundreds if not thousands of laser vendors on the internet. Yes, you’ll also find very cheap laser pointers and those that claim to be “burning” lasers without much specifications. There are a couple of explanations for this and we just want to give you facts. The first thing that comes to mind is the use of low grade laser diodes usually manufactured by small sized factories in China.

While these diodes work initially, they have very high possibility of burning out due to low grade parts and imprecise workmanship and alignment.

The parts used are usually off-spec or are left-over from over production. If it’s a 532nm green laser, it maybe using a relatively high powered 808nm laser diode coupled with cheaper, low conversion crystals. Without getting too technical, the last thing we want to bring up is customer service. Vendors for cheap laser pointers know that consumers are not too upset when a cheap laser stops working. In fact, these vendors thrive from buyers that pay for replacements. If you have already purchased a cheap laser that has broken, you should consider upping your laser buying budget.

Laser Application

Lasers are bright and sometimes too bright for pointing purposes. If pointing is your major application, stick to the laser pointers in the lower power output range. Some handheld and portable lasers are not laser pointers and are not suitable for pointing, especially indoors. Below you’ll find a table with suggestions for power outputs for indoors pointing for each color of lasers we offer in the laser pointers.

Color Classroom Audtiorium Outdoors
Violet 5-50 mW 80mW Choose blue/green
Blue 5 mW 50mW 80mW
Green 5-15 mW 20mW 50mW
Red 5-50mW 80mW Choose blue/green

Again, if you’ve read through our guide thoroughly, our eyes are sensitive to different colors making green laser light more visible compared to others. I did not include suggestions for nighttime pointing merely because the more powerful the laser, the more visible a laser will be. If a visible laser beam in darkness is required for your application, we suggest purchasing green or blue laser in a respectable power range. Please note that the beam of a 5mW violet or red laser is not visible in darkness.

Laser Safety

Lasers are great, but they can also be hazardous if you don’t treat them with respect. They can cause damage to the skin, eyes and even start fires. Here’s

  • Try to avoid contact with the skin or eyes at all times. Of course, the stronger the laser the more you need to be cautious of this.
  • Never point the laser at anyone near you.
  • Be wary of reflective surfaces
  • Avoid using binoculars and microscopes when
  • Use glasses when necessary.
  • Monitor children when using a laser at all times – don’t let them handle a laser of high mW under any circumstance.
  • Don’t point your laser at vehicles, planes or any other moving object.
  • If necessary, wear safety glasses.

Laser Safety Glasses

Our high powered lasers are very bright and just looking at the spot and diffused laser beam when pointed against a wall may damage your eyes, especially a light colored surface.

Lighting a match would require pointing and holding the laser spot on the match head where your eyes are also required to focus on the beam’s reflection to ensure the laser is on target. This is similar to staring straight into the sun.

Another situation where wearing laser safety glasses is essential is if you’re working with a laser indoors. There are windows, mirrors, and various reflective objects that may reflect the laser beam back at you. Accidents happen to even the most careful technician that has worked with lasers for many years, don’t think for one second that you maybe safe from mistakes.

As general advice, we suggest purchasing a pair of laser safety glasses when you buy a laser from us. Laser safety glasses are wavelength dependent so it’s important that you wear the correct protection for the laser you’re working with.

For instance, if you’re working with a 532nm green laser, you’ll need glasses that protect against this wavelength.

Please note that these same glasses will NOT work against red or infrared lasers. When choosing a pair of safety glassestore, make sure to choose the color of laser you work with.

Are Lasers Legal?

The Food and Drug Administration (FDA) is the governmental body in the United States that regulates lasers. As there are concerns that our laser products are illegal, we would like to clarify that lasers are perfectly legal to own under federal law in the United States. Some state laws may require lasers to be registered, please check with your local state laws if this is a concern for you.

While consumers have the right to own lasers, it’s also up to the consumer not to break any laws using the laser such as shining it at an aircraft which is a felony in the United States. We are not responsible for what you do with the laser.

While there’s nothing illegal about owning a laser, FDA regulations do require laser manufacturers to ensure the lasers are properly labeled and have the appropriate safety features required according to FDA standards.

Laser Classifications

Since we’re on the topic of the FDA and legality of lasers, let’s take a look at how lasers are classified. At the moment, there are two popular classification systems, the old version used before 2002, and a “new version” that is part of the revised IEC 60825 standard and ANSI Z136.1 standard. Since 2007, the new version has been accepted by the FDA for importing lasers into the United States.

FDA Class IEC Class Laser Product Hazard Product Example
I 1, 1M Non Hazardous CD/DVD players
II, IIa 2, 2M Slightly increased hazard Regular Laser Pointers
IIIa 3R Momentarily hazardous Stronger laser pointers
IIIb 3B Skin & Eye Hazard Laser light show projectors,
V 4 Immediate skin, eye and fire hazard Industrial and research lasers

Conclusion

Thanks for reading through this laser buying guide that is constant work in progress. We hope it has given you enough insight into portable laser technology so you can make an informed decision on which laser is most suitable for you. We hope you have enjoyed this guide. We’re always looking to improve this guide and would love your input and ideas about what topics needs to be included or which sections need clarification.