Is LED Light Monochromatic?

LED lights are the best thing to happen to the lighting market. Most of us use them every day – you are possibly using one as you read this.

LED lighting has revolutionized the industry. While they are available in many colors, we need to dig into this a bit.

Monochromatic light means that the light has a single wavelength. The LED light is not monochromatic because it is made up of different wavelengths, therefore is polychromatic.

In this article, you will learn:

  • The meaning of monochromatic light
  • Differences between monochromatic and polychromatic light
  • How wavelengths affect colors that LED lights can produce

Read on, and all will be revealed.

What Does Monochromatic Mean?

Monochromatic simply means a single color or one color only. The best way to understand it is to break it down into the Greek origin of the word – “Monos” being one and “khroma” being color.

The basic scientific definition is that the light is all of the same wavelength. As color is the result of different wavelengths of light, monochromatic light is all derived from a single wavelength.

It is relatively rare to find monochromatic light.

People might say a room done out in all red is monochromatic. Strictly speaking, this would not be correct as there are sure to be different red shades, even if subtle.

This means that there is a range of wavelengths of light.

The opposite of monochromatic is polychromatic. It is made up of different wavelengths.

One that often confuses people is white light, which is polychromatic. It is made up of various wavelengths.

See the difference?

Another way to understand is through example.

Sunlight is polychromatic as it is made of a range of wavelengths. It includes UV and infrared light and anything in between.

Just remember the last time you have seen the rainbow.

On the other hand, laser light consists of only one focused wavelength.

Is LED Monochromatic Or Polychromatic?

Strictly speaking, LED light is not monochromatic. If we look at the definition above, monochromatic light derives from one wavelength.

LED light, even if it appears to be one color, is made up of different wavelengths, measured on a spectrometer.

Spectrometer reads and measures the various wavelengths.

If you look at LED lights through a spectrometer, it will clearly show a range of wavelengths.

Sure, it might look all the same color to the naked eye but actually consists of various wavelengths, making it polychromatic light.

This is better understood by looking at a spectrometer reading. Look at the image below, which shows LED lighting wavelengths breakdown.

Source: Quora – Marko Sokolich

You can see apparent peaks, and there is some spectrum width, which simply shows various wavelengths.

You may believe you are seeing monochromatic light at the output, it is not the case in the real sense of the word.

The graph would have to be a perfectly vertical line for monochromatic light.

Although the spectrum of LED lights is narrow, it still falls outside of the definition of monochromatic.

Again, it is necessary to note that we are talking about the term’s strict scientific definition.

In general, most people will still refer to light that looks to come from a single light source, color, or wavelength, to be monochromatic.

It depends on how technical you want to get.

How Many Wavelengths Do LEDs Emit?

The color emitted by an LED light is measured in nm or nanometers, which is determined by the lpk or peak wavelength.

The materials used in the LED will determine the lpk. The wavelength range for most LEDs is between 360 to 950 nm.

What does it mean?

Each color is made up of different wavelengths. Not all, in fact, many are not even visible to the naked eye.

The LED’s specific makeup and the materials used will determine the wavelength that dictates the color produced.

Often, a combination of wavelengths is used to create different colors.

Have a look at the table below where I compare wavelengths and colors they produce:

Wavelength (nm) Color
380 – 450 Violet
450 – 485 Blue
500 – 565 Green
625 – 740 Red

A key takeaway is that different materials or combinations of materials create the different wavelengths and thus the color that is produced by the LED.

How Many Colors Can LED Produce?

rgb concept

LEDs can produce 16.7 million colors. In many cases, the human eye will not be able to discern the difference between them.

Any artist or color specialist will tell you, all colors originate from the three primary colors, red, green, and blue. This is known as the RGB model.

The ways these three colors are combined can make up a broad spectrum of colors. Combining all three equally creates a white color.

Mixing the combination up offers a vast range of options. This will vary according to the source of the primary color as well as the medium.

It is not consistent unless all elements are the same.

Suffice to say, LEDs are versatile and capable of creating many different colors. More than enough for any application.

On that note, I would like to add that LED lights are based on the RGB model, which differs from the subtractive color model, also known as CMYK.

The CMYK model is made of cyan, magenta, yellow, and black. When you overlap the first three, you will get the black color instead of white in the RGB model.

Color printers generally use the CMYK color model.

Final Words

So what does all this mean?

Polychromatic light has multiple wavelengths, and LEDs fall into this category.

A vast range of materials and combinations are used to create different colors. Many of these can not be seen by the human eye.

  • Did you know that LED light is polychromatic?
  • Have you ever heard the term monochromatic and polychromatic?

I would love to read your take on that below.

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