Green vs. Red Laser: Which one is brighter?

If you observe all the lasers in the market today, you’d notice that they have a variety of colors. There’s a scientific explanation why laser pointers can have different colors. The different colors are mainly based on their wavelength (or frequency). It can also be contributed by the materials used to produce the lasers.

Read on to find out what best explains why a laser beam might appear green and another, red. Also, you can figure out how these lasers with different colors are produced.

A brief overview of the laser

Type of lasers

First, let’s dive into all the laser types. The difference in laser type is mainly due to the lasing material used. There are 5 main types of lasers available today and these are:

  • Solid-state lasers use solid matrix like ruby or neodymium:yttrium-aluminum-garnet (Nd:Yag)

  • Gas lasers use helium and helium-neon (HeNe)

  • Dye lasers use complex organic dyes like rhodamine 6G; can be tuned to any wavelength

  • Semiconductor lasers use laser diodes; very small and low powered

  • Excimer lasers mix reactive gases like chlorine and fluorine with inert gases like argon, xenon, and krypton

These varying lasing materials are responsible for the level of wavelength and power output emitted by the laser.

How laser pointers produce different colored lights

Second, let’s explore how light is produced. There are two ways an atom can produce light and it’s through spontaneous emission or stimulated emission. Spontaneous emission is when the energy source within the laser emits light all by itself. It does that when the energy source (atom, molecule, or subatomic particle) moves from a high (excited) energy state into a ground state (low energy level). Spontaneous emission occurs at random intervals.

spontaneous stimulated emissions

On the contrary, stimulated emission refers to the interaction between an incoming photon with a specific frequency and an excited atom. Once they interact, the photon will bring the excited atom to a lower energy level. Here, the atoms are stimulated to produce radiation, hence the term stimulated emission. What happens next is a chain reaction of photons that would produce coherent light, coining the term laser, or Light Amplification by Stimulated Emission. Although the colors are different, all laser pointers use stimulated emission to produce light.

Red, orange, yellow, green and blue lasers

As stated above, the difference between red, orange, yellow, green and blue lasers lies mainly on their wavelength or their source type. The following table explains the difference between the green laser, red laser, orange laser, yellow laser, and blue laser pointers.

Laser Color

Laser Type

Wavelength (nm) or frequency (Hz)

Red

A battery-powered laser diode, or diode-pumped solid-state laser

Up to 680nm

Orange

​Diode-pumped solid-state laser, with complex lasing lines of ND:YVO4, 1064 nm, and 1342nm

593.5nm

Yellow

Diode-pumped solid-state laser

589nm

Green

Diode-pumped solid-state frequency-doubled laser

532 - 555nm

Blue

Diode-pumped solid-state frequency-doubled laser or Blu-ray

360 - 480nm

You can also determine the color and wavelength by the type of energy source your laser pointer uses. Take a look at the following table:

Laser Source Type

Wavelength (nm)

Argon fluoride (UV)

193

Krypton fluoride (UV)

248

Xenon chloride (UV)

308

Nitrogen (UV)

337

Argon (green)

514

Helium-neon (green)

543

Helium-neon (red)

633

Rhodamine 6G dye (tunable)

570-650

Ruby (CrAIO3) (red)

694

Nd:Yag (NIR)

1,064

Carbon dioxide (FIR)

10,600

Which best explains why one laser beam might appear blue and another laser beam might appear red?

What best explains why one laser beam might appear blue and another laser beam might appear red lies on their wavelength. As stated previously, a laser’s wavelength or frequency is responsible for its color.

visibility light chart

If you see the chart above, red and blue lasers lay on opposite ends of the curve. Blue lasers have a wavelength ranging from 400 to 500nm with only 3% visibility to the human eyes. Meanwhile, red lasers have a wavelength with the range of 650 to 700 with visibility of 24%. Green lasers, on the other hand, possess the most visibility ranging from 88% to 100%. However, they don’t have the highest wavelength, placing at 532 to 555 nanometers on the wavelength scale.

On the far left and far right side of the curve, we have ultraviolet and infrared respectively. Ultraviolet has a wavelength of 193-337nm while infrared has a wavelength of up to 10,000nm. This makes these two laser lights invisible to the naked eye as the range of visibility for the human eyes is 390-780nm.

During the stimulated emission stage, the energy of the photon produced contributes to what the laser color will be. So, the higher energy photons that are produced, the shorter the wavelength of the light will be. This means blue laser lights produce high energy photons while red laser lights produce lower energy photons.

Uses for red, orange, yellow, green and blue lasers

These different-colored laser pointers are used for various reasons and in various places. For instance, the red laser pointer, which is the most popular type of laser pointer, can be used for casual use. This includes during presentations, for light photography, science experiments, to entertain your pets, and more. This is because red laser pointers of less than 5mW can cause the least amount of potential damage.

stars pointing

On the other hand, since green laser pointers are generally more visible and powerful than red laser pointers, its uses are more focused and specific. For example, green laser pointers are used for astronomy, especially stargazing. Green lasers have a light that is brighter, can also be visible during daytime, and the light can go for longer distances than red lasers. Green lasers are also used as a laser sight for guns and rifles.

Next, yellow and orange lights are typically used in hospitals. They can help treat viral infections sclerosis, and even psychological illnesses like panic attacks, anxiety disorders, and depression. Aside from treating major injuries and mental sicknesses, yellow lasers can also be found in skin and aesthetic clinics. It helps get rid of acne, stimulate collagen production, reduce redness and inflammation, and promote new skin growth.

Blue lasers possess shorter wavelength than all the other colors. This means blue laser beams can have a stronger focus or resolution. Because of its stronger focus, blue lasers are typically used in the interferometers such as laser printers, compact discs, data recording, digital photofinishing, and DVD or CD players.

Now that you have the gist of why some lasers appear blue and some appear red, you can choose a laser pointer with the color that is most suitable for you.

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  • Updated August 9, 2019
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