Laser vs Light
Light is a form of electromagnetic waves visible to human eyes, hence often referred to as visible light. The visible light region is positioned in between the Infrared and the Ultraviolet regions of the electromagnetic spectrum. Visible light has a wavelength between 380nm and 740nm.
In classical physics, light is considered a transverse wave with a constant speed of 299792458 meters per second through a vacuum. It displays all the properties of transverse mechanical waves explained in the classical wave mechanics such as interference, diffraction, polarization. In the modern electromagnetic theory, it is considered that the light has both wave and particle properties.
Unless disturbed by a boundary or other medium, light always travels in a straight line, and it is represented by a ray. Even though the propagation of light is straight, it disperses in three dimensional space. As a result, the intensity of light reduces. If the light is generated from an ordinary light source, such as an incandescent bulb, the light may have many colours (these can be seen when the light passes through a prism). Also, the polarization of the light waves is arbitrary. Therefore, light is absorbed by the material during the propagation. Some molecules absorb the light with a specific polarity and let the others pass. Some molecules absorb the light with specific frequencies. All these factors contribute and the intensity of the light dramatically drops with the distance.
When a light is needed to be carried to a further distance, we have to overcome these issues. It can be sent further by keeping the light waves parallel throughout the propagation; using the alliance system, dispersing light waves can be directed into a single direction, to travel parallel. Also, using light with one colour (monochromatic light – light with a single frequency/wavelength is used) and fixed polarity the absorption can be minimized.
Here, the problem is how to create a light radiation with fixed wavelength and polarity. This can be achieved by charging specific material in a way that they are giving off the light by only a single transition in the electrons. This is called stimulated emission. Since this is the basic principle behind generating a laser, the name carries it. Laser stands for Light Amplification by Stimulated Emission of Radiation (LASER). Based on the materials used and the method of stimulation, different frequencies and strengths can be obtained from the laser.
Lasers have numerous applications. They are used in all the CD/DVD drives and other electronics appliances. They are widely used in medicine too. High intensity lasers can be used as cutters, welders, and in metal heat treatment.
What is the difference between Laser and (Normal/Ordinary) Light?
• Both light and LASER are electromagnetic waves. In fact, laser is light, structured to behave with specific characteristics.
• Light waves get dispersed and get absorbed heavily when travelling through a medium. Lasers are designed to have minimal absorption and dispersion.
• Light from an ordinary source disperse in 3D space hence each ray travel at an angle to each other, while lasers have rays propagating parallel to each other.
• Normal light consists of a range of colours (frequencies) while the lasers are monochromatic.
• Ordinary light has different polarities, and the laser light has plane polarized light.