Many practical gadgets use laser light to achieve various functions such as fibre optic communication, laser printing, 3D printing, medical imaging, 3D imaging with LIDAR, etc. Even daily devices such as smartphones and gaming controllers use infrared light for facial detection and motion control. Such applications are made possible by the fact that these devices are able to project, manipulate and detect complex patterns of laser light, as required by the application. The key component that makes this possible is an optical element that manipulates the laser light called diffractive optical elements (DOE).
DOEs work is based on the principle of optical diffraction discovered many decades ago. DOEs consist of tailored micro-structures that alter the phase of the incident light (typically lasers), allowing it to change the shape, profile, and amplitude of the laser. Advances in microfabrication techniques have allowed for fabrication of DOEs with sub-wavelength microstructures that have enabled a sea of novel possibilities. DOEs:
- Offer many novel optical characteristics which cannot be realized using traditional refractive or reflective optical elements
- Are smaller, thinner, and lightweight making them extremely compact and easy to integrate
- Are highly precise with negligible angular tolerances and robust long-lasting performance
- Can be made on many materials such as Fused Silica, Germanium, Zinc Selenide, Polymers, etc.
DOEs work is based on the principle of optical diffraction discovered many decades ago. DOEs consist of tailored micro-structures that alter the phase of the incident light (typically lasers) Click To Tweet
DOEs that manipulate the incident laser light to produce a well defined output beam with uniform intensity are called beam shaping elements. Such elements can be used to produce spots of typical shapes such as round, square, or any arbitrary shape as desired. Such elements are commonly used in spectroscopy, 3D imaging and medical diagnostics. Beam shaping DOEs include both diffractive and broadband diffusers (suitable for shaping multimode laser beams) and analytical beam shaper, that provide unparalleled shaping accuracy for single mode beams.
beam splitter elements are DOEs that split the incident laser light to produce several well-defined output beams (called “orders”) with controlled intensities. The output beams pattern can be arranged in shapes such as a square, line, round, hexagon or any other arrangement as desired including pseudo-random patterns, with precise separation angles between the beams. Such elements are routinely used in laser scribing, laser micromachining and in medical aesthetic treatments. Beam splitting DOEs can be tailored for:
- Accurate separation angles
- Any wavelength from UV to IR
- Any desired number of orders and intensity of orders
DOE that primarily manipulate the focal properties of the incident laser light are called beam foci elements. They can be tuned to alter the depth of focus, split the laser focus into several foci with controlled focal separations or focus several wavelengths into the same exact focus plane. Such elements are used in Laser glass cutting, light-sheet microscopy, cytometry, and other applications involving transparent materials. Beam foci DOEs have the following families:
- Increased depth of focus – Elongated Focus DOE
- Splitting of an incident beam into multiple foci with uniform separation – Multi-focal DOE
- Focusing several wavelengths to the same plane – Diffractive achromat
With such useful properties DOEs are poised to bring about immense benefits to optoelectronic laser systems in the coming years.