A diffractive beam splitter refers to a diffractive optical element or DOE which is used to bifurcate a single collimated laser beam into multiple beams with the optical features like the original beam. The beams are usually bifurcated in one dimensional or two dimensional arrays and can be organized regularly or irregularly. A diffractive beam splitter can be used with the monochromatic light like a laser beam and is meant for a specific wavelength and the angle or separation between the output beams.
The working principles of a diffractive beam splitter are very much like diffraction grating but when it comes to DOE, the grooves of diffraction grating have more complicated shapes in 1D array or DOE has complicated binary or analog format surface with the 3D periodic structure. The diffractive beamsplitter lets you to make any kind of spot arrays like 1D, 2D or irregular and simultaneously maintain high efficiency and even distribution of energy in the spots.
The application of diffractive beam splitters are
- Laser scribing and dicing
- Laser displays
- Filters for cigarettes
- Medical or aesthetic applications
- 3-D sensors
- IR depth detectors
- Fiber optics
Diffractive optics are also just another tool for making an optical system. They can perform tasks that the refractive optics cannot and hence are lighter and smaller than the refractive optics. Hence, always remember that, but the benefits of Diffractive Optical Element or DOE also come with a cost. DOE has its own limitations. They are tough to give away and usually give the desired results under very special conditions.
Just like any other tool available to a lens designer, DOE has its own uses as well. They can bear a strong negative dispersion which comes in handy for rectifying the chromatic abertation as they produce random illumination patterns that would be really hard to make with genuine refractive optics. Eventually, they are more like Fresnal lens but with tiny features. It is also vital to understand that a Fresnal lens is a diffractive optic. As a matter of fact, diffraction is a deep subject in itself, and you may realize that in some way all lenses are diffractive optics. While you can make the phase profile of DOE to have a more complex optical field, you can also create one to have a simple focal spot, the outcome design would be a simple lens.