Before we can learn about we need to know a little bit about light (since that is what a laser is made of). Light from our sun, or from an electric bulb, is called white light. It is really a mixture of all the different colours of light. The colours range from violet, indigo, and blue, to green, yellow, orange, and red. These make up the visible part of the electromagnetic spectrum. Light is made up of particles, called PHOTONS, which travel in waves. The difference in the colour depends on the wavelength of the light. Violet light has the s ....