Electromagnetic Spectrum

You know more about the electromagnetic spectrum than you think! The electromagnetic spectrum, EM for short, is the group of all types of radiation found in this world. Radiation is energy that travels and spreads out as it goes and can be categorized by wavelength or frequency. Visible light that comes from our green lasers and radio waves that come from radio stations are two types of electromagnetic radiation. Other examples of EM radiation are microwaves, infrared and ultraviolet light, X-rays and gamma-rays. Each type of EM radiation is denoted by a specific wavelength or frequency spectrum. See the diagram below:

Looking at the diagram above, we see each type of EM radiation can be categorized by a section of laser wavelength or laser frequency. It is important to note that our eyes are sensitive to light in the visible spectrum only, that is, we are unable to visibly see any other types of radiation. The visible spectrum has wavelengths roughly between 380-750 nm (nanometers) and frequencies between 400-790 THz (teraHertz). Each wavelength section of the visible spectrum represents a certain color:

1. Violet: 380–450 nm
2. Blue: 450–495 nm
3. Green: 495–570 nm
4. Yellow: 570–590 nm
5. Orange: 590–620 nm
6. Red: 620–750 nm

When you look at a colored object, you actually see the reflection of radiation in the visible spectrum. Let’s take a leaf for example. Leaves are green NOT because they emit green photons. You see green because only green radiation is reflected off the leaf’s surface. All other wavelengths are absorbed.

Our lasers are most well known for its bright visible beam. Our visible beam lasers emit lasers with a wavelength and frequency in the visible spectrum. According to the luminosity function, the human eyes are most sensitive to green light around 555nm. Therefore, you will find green lasers with a wavelength of 532nm to emit the brightest of all visible laser types!