All the Light We Can and Cannot See

by | Oct 2, 2019 | Blog

While we tend to think of light as illumination, that is only true for a small portion of light in the visible spectrum. There is a lot of light that we just can’t see – that’s invisible to the naked eye. There are also concerns that might not be as apparent about certain types of light, like blue light, which is prevalent in LED technology.  And because our technology makes LED lighting healthier than current LEDs, this article provides some background on aspects of light that most of us don’t see but affect us nonetheless.

Light is electromagnetic radiation which is comprised of particles, or photons, that travel in waves. Different types of light have different wavelengths and frequencies. Humans can see wavelengths ranging from 380 to 740 nanometers (nm — a nanometer is one billionth of a meter) or that have a frequency from approximately 430 to 770 terahertz (THz), while other species can see light at other wavelengths. Bees, for example, can see ultraviolet light, which helps guide them to a flower’s nectar.

The wavelengths of light comprise the Electromagnetic Spectrum, ranging from the longest to the shortest: radio waves, microwaves, infrared, visible light, ultraviolet light, X-rays and gamma-rays. There is an inverse relationship between wavelength, and frequency and energy, so the shortest wavelengths have the greatest frequency and energy output, and vice versa.

Color is in the eye of the beholder

Color is one of the key characteristics we think of when it comes to light. Interestingly, objects do not have any color, but rather it’s the way they reflect light that creates our perception of color. On a biological level, our retina has rods and cones which perceive and respond to light and send messages to the brain which translates light into the colors that we see. Humans can see approximately 10 million colors.

Visible Light

Sir Isaac Newton was credited with being the first person to separate light into colors by using a prism. The colors of visible light in most spectrums today range from violet – with the lowest wavelength of 380-450 nm and highest frequency of 688-789 THz and greatest energy – followed by blue, green, yellow, orange and red (with a wavelength of 620-750 nm and a 400-484 THz frequency). Indigo was originally included in Newton’s spectrum since he wanted seven colors to correspond to the number of musical notes. However, many people cannot distinguish between indigo and blue or violet.

Blue light

With one of the shortest wavelengths of visible light, blue light delivers high energy, making it a very attractive energy source. LED lights, which contain a lot of blue light, are very efficient, emitting a lot of light without discharging much heat. For that reason, in today’s energy conscious environment, LEDs have become very popular for both home and business use.

However, there are health concerns about using blue light. It can cause vision issues, including retinal damage, interfere with our circadian rhythms regulating our hormones and wake/sleep cycle, and according to a Harvard study could contribute to diseases such as diabetes, cancer and heart disease.

We’re writing more about the impact of blue light in other articles, including The Problem with Blue Light at Night and The Impact of Blue Light on Shift Workers, so if you’re interested, please check our blog for more content.

Nonvisible light

  • Radio waves – Radio waves have wavelengths from about 0.04 inches to more than 62 miles.  Radio waves, which we use every day for television, radio, mobile phones, etc., are transformed into sound through mechanical vibrations in a speaker.
  • Microwaves – While cooking comes most frequently to mind when we think of microwaves, they are also used for point-to-point communication and radar to “see” objects and their location. The wavelength of microwaves varies from about 0.04 inches to 12 inches.
  • Infrared – Infrared light, which spans a range of wavelengths, has many uses including sending a signal from a remote device to a television set to change channels or volume, to detecting objects through the radiation they emit, and radiating heat for heat lamps and toasters. Along with conduction and convection, infrared radiation is one of the ways that heat can be transferred from one place to another. The wavelengths vary from about 1 millimeter to 760 nanometers (just under 3 inches). Frequencies range from about 3 gigahertz (GHz) to about 400 THz.
  • Ultraviolet light – This is the type of sunlight that is responsible for sunburns. Ultraviolet light emits enough energy to break the bonds of chemicals, which can be used in chemical processing and as disinfectant since it kills bacteria. It is also used for tanning booths, halogen lights, fluorescent lights and some types of lasers. Ultraviolet light is emitted in a range of wavelengths from about 380 nm to about 10 nm.
  • X-rays – Because this type of electromagnetic radiation emits a great deal of energy that can penetrate objects, we are familiar with its uses to view the contents of luggage for airport security, see the images of bones, and to kill cancer cells through radiation therapy, among other uses. There are two types of X-rays, soft X-rays with wavelengths of about 10 nanometers to hard X-rays with wavelengths of approximately 100 picometers (a picometer is one trillionth of a meter).
  • Gamma-rays – With the smallest wavelength, gamma rays produce the greatest amount of energy in the Electromagnetic Spectrum. They are emitted from neutron stars and other very hot objects in the universe, and can be found on Earth through nuclear fission and fusion, lightning and the radioactive decay of matter. Gamma-rays can be used to treat cancer. The wavelength of gamma-rays is up to 1/10 of a nanometer. 

Here at Aurea, we have developed an innovative solution that allows people to enjoy the energy efficiency benefits of blue light without the associated health problems. We’ve been focusing on converting the wavelength of blue light, rather than filtering it. Our approach combines a patented energy conversion film that contains organic dyes with a high-efficiency blue LED light source that is converted into a healthy light which minimizes melatonin suppression at night and circadian rhythm disruption.

These lights meet both the mood-based psychological and biological needs of the human body – and at the same time, maintain the energy efficiency of LED lighting. We provide healthier LED lights without degrading energy efficiency, a typical drawback of other solutions that filter out blue light.

Our solution creates a highly efficient, human-healthy blue light that brings our world into better light. If you have any questions, we’d be happy to talk. You can connect with us by email at or by phone, (978) 459-4500.

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