Decoding Light: Exploring the Functionality of Diffractive Beam Splitters

Diffractive beam splitters are diffractive optical elements or DOEs that  split an input laser beam into several output beams where the characteristics of the input and output beams remain the same. Even though the size, polarization, divergence, beam quality, and intensity distribution remain the same, the power and angle of propagation of the output beams are different from the input beam.

Like any other diffractive optical element, a diffractive splitter is designed to operate at a particular wavelength. One can design a diffractive beam splitter to produce either a one-dimensional beam array or two-dimensional beam matrix, with any power ratio per order. This flexibility of design can achieve any desired spot  arrangement required for the laser application.

Applications of Diffractive Beam Splitters

Diffractive beam splitters have a wide range of applications in aesthetic/medical and industrial sectors. Some useful applications are:

  • Fractional skin treatments in aesthetic/medical field,
  • Laser soldering and welding methods,
  • Laser scribing in solar panels, displays, and cells,
  • Laser perforation,
  • Laser cutting/dicing,
  • IR depth detectors,
  • Machine vision applications and dot generation in three-dimensional sensing.

The Efficiency of Diffractive Beam Splitters

Apart from diffractive beam splitters there are two other common types of beam splitters, such as plate beam splitters and Microlens arrays.

A plate beam splitter generates two different output beams from an input beam, such as transmitted beam and reflected beam. The divergence and beam size of the output beams remain same as the input beam and the angle of incidence determines the direction of the output beams. A Microlens arrays produces several smaller output beams by splitting the input beam, each with different divergence and M2 compared to the input beam. This beam splitter involves an arrangement of several tiny lenses of same size and radius of curvature or lenslets to split the input beam.

The versatility and efficiency of diffractive beam splitters is much better than the above-mentioned other two types of beam splitters. Microlens arrays operate based on the refractive principle, whereas the diffractive beam splitters follow the principle of diffraction to exploit the wave nature of the input beam. The output transmission by diffractive beam splitters is known as the interference effect. The major advantage of using a diffractive beam splitter is that it can obtain any geometrical beam pattern while splitting the input laser beam into multiple output laser beams. In output beams, the beam size, inherent divergence, and other optical characteristics remain the same as the input beam. By using diffractive beam splitters, one can also design the output beam’s angular orientation and spatial separation at any desired value. Because of the high efficiency of the diffractive beam splitters, these beam splitters have substantial applications in various fields. From monitoring the laser power, skin treatments to laser scribing, laser dicing, 3D sensing, and fiber optics, diffractive beam splitters are useful.