Glossary of Basic Laser Terms

Alignment: Laser alignment is a measure of the deviation of the optical axis of the laser beam with respect to the mechanical axis of the laser housing. Some laser diode modules feature an adjustable alignment for precise positioning applications.

Coherence: The alignment between light wave wavelength and the position of that wave in its oscillation cycle. When the crests and troughs of several light waves are in alignment, they are coherent.

Continuous Wave: The light emitted from a laser is in a steady, continuous beam.

Divergence: The angular measurement of laser beam spread with distance. The projected dot of a laser will increase in size the farther it is projected. Laser divergence is measured in milliradians (mrad).

Diode: An electronic device that conducts a current in only one direction.

Diode Laser: A laser that emits coherent light through the injection of electric current into a semiconductor diode.

Fan Angle: The measure of angular spread of a line-generating laser. The fan angle determines the line length produced at a certain distance. CALPAC line-generating lasers have a 90° fan angle. A 90° fan angle will produce a line length that is 2x the projection distance (e.g. a 10 foot long line when projected from 5 feet).

Laser: Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. It's a device that produces an intense, monochromatic, coherent beam of light by stimulating electronic energy levels.

Laser Class: In order to regulate laser safety, the Center for Devices & Radiological Health (CDRH) classifies lasers into different categories based on wavelength and output power:

          Class II: Visible laser light less than 1.0 mW.
          Class IIIa: Visible laser light from 1.0 mW up to 5.0 mW.

Laser Diode Module: A complete laser assembly including all circuits, a laser diode, and optics packaged in a protective housing. All that is required for operation is an appropriate external power supply.

Milliamperes (mA): A unit of electrical current equal to one-thousandth of an ampere.

Milliradian (mrad): A unit of angular measure equal to one thousandth of a radian (1 radian = 57.295 degrees).

Milliwatt (mW): A unit of power equal to one-thousandth of a watt.

Nanometer (nm): A unit of measure equal to one-billionth of a meter.

Operating Voltage: The range of specified input voltage required to operate a laser. Laser operating voltage is measured in volts (V).

Operating Current: The range of specified current required to operate a laser. Laser operating current is measured in milliamperes (mA).

Output Power: The energy per second emitted from a laser. Laser output power is measured in watts (W) or milliwatts (mW) for continuous wave laser operation.

Semiconductor: A substance through which the flow of electricity can be controlled.

Visible Light: Electromagnetic radiation that is visible to the human eye. The Visible Light Spectrum encompasses the range of wavelengths between 400 to 700nm. Green light is in the spectral range of 520 to 565nm. Red light is from 625 to 700nm.

Volt (V): The basic unit of electromotive force or potential difference.

Wavelength: The measured travel distance from peak-to-peak of an electromagnetic wave during one cycle of oscillation. Wavelengths of light are measured in nanometers (nm). The wavelength of a typical red laser will be either 650nm (bright) or 635nm (brighter). The typical wavelength of a green laser is 532nm (brightest).