Diffractive Optical Elements (DOEs), occasionally mentioned as digital diffractive optics, are phase relief elements that routines micro-structures to alter the phase of the light propagated through them, and thus use it in various ways to create shapes and light patterns that are either impossible to accomplish in different methods using refractive optics, or require very complex, bulky and expensive optical components and/or systems.
The important thing to know about diffractive optical element basics is that due to its principle of operation, i.e. – the phase delay created by the microstructures, a DOE is intended for a discrete wavelength and is thus appropriate for use mostly in laser systems. A source with narrow bandwidth around the nominal wavelength will toil properly with minor eccentricities from the optimum.
Benefits of using diffractive optical elements:
- It has the perfect angular accuracy with zero tolerance.
- They are flexible shaping and have splitting capabilities with a single compact component. They are also flat, thin, and lightweight.
- They are passive components with no electronics or mechanical moving parts (unlike other beam shaping resolutions such as scanners or modules). Thanks to their production qualities, they have a high laser damage threshold alike to that of a window made of the same substrate (typically laser grade Fused-silica or Zinc-Selenide). They make the system robust and require very low maintenance for their furnishing.
- Diffractive optical elements being a single flat component, are easily unified into any optomechanics. They can be fabricated at ordinary or custom dimensions to fit manufacturers’ precise system tolerances, or be used with typical optical mounts. Some optical elements are planned, such as top-hat beam shapers, and need accurate alignment tolerances, specifically centration and beam size.
Diffractive optical elements, powerful as they may be, are submissive elements, a quality that is a benefit in many applications but postures a restraint for others. In many applications, the suppleness of creating various optical functions on the same optical path is an advantage optical element lack. To address this issue, it has recently developed a new method for Variable Function Beam Shaping. These elements contain more than one optical function on the same surface but in different areas.
With these unique elements, mounted on a moving or rotating stage, or with an additional component to stir the input beam, one can design an active beam shaping system that enjoys all the great advantages of diffractive optics including excellence, precision, and firmness, while still enabling flexible shaping.