Introduction to Laser Technology

Since the 80’s, high power lasers have entered the material processing industry in full force due to their capability to cut, weld, drill, mark, and clad metal. Lasers can now be found in just about any shop performing these kinds of operations.  A laser is a device that emits light through a process called optical amplification based on the stimulated emission of photons. The term “laser” is an acronym:

  • L – Light
  • A – Amplification by the
  • S – Stimulated
  • E – Emission of
  • R – Radiation
laser light specturm
laser cutting wand chicago slitter

The left diagram below depicts a typical beam of light waves from an ordinary source (light bulb). One can see that these waves do not have any fixed relationship with each other. This light is said to be “incoherent”, meaning that the light beam has no internal order. The right diagram, on the other hand, illustrates the light waves within a highly collimated laser beam. All of these individual waves are in step (or “in phase”), with one another at every point. “Coherence” is the term used to describe such a property of laser light.

Unlike natural light from a bulb or the sun that is of many different wavelengths, emitted laser light is notable for its high degree of spatial and temporal coherence (or wavelength), unattainable using other technologies.

Spatial coherence Chicago slitterSpatial coherence typically is expressed through the output being a narrow beam which is diffraction limited or a straight beam. The beams can be focused with a lens to very tiny spots, achieving a very high irradiance (energy per area) or they can be launched into a beam of very low divergence (expansion) in order to concentrate their power at a long distance away (i.e. the moon or Sears Tower).

Temporal (or longitudinal) coherence implies a polarized wave at a single frequency whose phase is correlated over a relatively large distance (the coherence length) along the beam. A beam produced by a thermal or other incoherent light source has an instantaneous amplitude and phase which vary randomly with respect to time and position, and thus a very short coherence length.
As the months go on, we will be introducing more educational bulletins regarding the technology as it relates to how they function as well as the laser systems to be installed in the company.

Recent advances in laser cutting technology have created a viable alternative to mechanical cutting of developed blanks from sheet metal coil stock. At one time laser cutting was too slow for developed blanks and only used for prototype and low volume production of complex shaped sheet metal blanks. For example, 10 years ago, laser cutting equipment could typically cut 1mm steel at 30m/min, today the speed has doubled! Cutting speeds now have increased to the point where the process can accommodate high volume, creating an entirely new market segment and set of opportunities within the steel coil processing industry.