How Laser Levels Work

The Technology Behind Laser Levels

Laser levels use a laser, an amplified, focused beam of light emitted from a solid-state device called a diode. These light emitting diodes, also known as LEDs, are found in many common devices, including digital clocks, remote controls, or television screens.

To understand how a laser works, it's helpful to know that the word is really an acronym for Light Amplification by the Stimulated Emission of Radiation. Simply put, when certain electrons are stimulated, they give off a beam of light. When mirrors or prisms collect this light and point it in one direction, the result is a laser beam.


Laser levels project a beam of light that can be used as a visual chalk line when a straight and level reference point is needed. The size of the beam of light depends on the size of the diode. In this case, smaller is better -- a smaller beam of light is more precise. With a wider beam of light, the actual point of "level" can be located anywhere within the width of the beam.

The first laser levels were limited to indoor use because the light of the laser was not bright enough to be seen outdoors. Today, more powerful laser levels can be used indoors or outdoors, and many are designed for use with a light detector that "reads" the laser's light. These devices are positioned away from the laser's diode, then moved up or down until the projection is detected and signaled in response with a beep or blink.

Most lasers emit a red beam of light. Some manufacturers are now offering green lasers that are 400 percent brighter than red laser beams, making them more visible for indoor applications. However, the technology that's needed to project green requires more power than a red light, so battery life is not as long lasting, and the red lasers are generally more accurate and more reliable over a range of temperatures.

Laser levels are usually manufactured with small, low-intensity diodes and are powered using rechargeable or alkaline batteries. As with any laser, looking directly at the light can be harmful to a user's eyes, so wearing safety goggles is always recommended. The light of a laser level should not be directed at another person.

Now that you know how these lasers work, let's learn how to use them.