Each laser application, from dentistry to materials processing, has unique performance requirements. Lasers vary in wavelength, optical power output, temporal properties, and other key performance characteristics. It is possible to produce laser families of various beam diameters and divergence angles, but it is nearly always easier to select a laser based on other performance requirements, and then use a laser beam expander to produce the desired beam diameter and/or divergence.

In addition to enlarging the beam diameter, beam expanders also reduce laser-beam divergence. They are often used to compensate for source-to-source beam variation. The beam-expansion ratio, power, or magnification is the primary specification used when selecting a beam expander. Specify beam-expander characteristics carefully, because each influences the complexity of design and manufacturing. A specific application’s needs may be met with an off-the-shelf, modified off-the-shelf, or entirely custom-designed laser beam expander. The overall system requirements drive the specifications of the beam expander.

Selecting a beam expander takes the same attention to detail as selecting other optical components, and can enhance the capabilities of a given laser and improve its performance in a given application. Although the system may have unique requirements, a custom beam expander may not be necessary. This is where a modified off-the-shelf beam expander or even an off-the-shelf system should be considered.