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Diffractive Optical Elements (DOE) - Diffractive Optics

Diffractive Optical Element DOE

Diffractive optics are making their way into industry. The areas of applications range from bio technology via printing, material processing, sensing, contact-less testing to technical optics and optical metrology. Diffractive optics provide value-add to laser systems. By incorporating diffractive optical elements (DOE) in the optical field of a laser beam, the beam's "shape" can be controlled and changed flexibly according to application needs.

The base here is the microstructure of the DOE which acts like a router for photons directing their way to propagate through free space. A Diffractive Optical Element utilizes a surface with a complex microstructure for its optical function. The micro-structured surface relief profile has two or more surface levels. The surface structures are either etched in fused silica or other glass types, or embossed in various polymer materials.

Functionality of Diffractive Optics

Diffractive Optical Element Lines

The technical discipline of diffractive optics provides methods to design and implement DOE microstructures in order to manipulate light and photons and by this implement a desired function. Remarkable progress in DOE design and implementation has been achieved within the last few years. Fabrication techniques have been proven to be reliable and cost-efficient. DOE have been shown to be effective in various technical applications. In some cases DOE have even opened the doors to new solutions.

Additionally, diffractive optics can realize almost the same optical functions as refractive optics such as lenses, prisms or aspheres, but they are much smaller and lighter. DOEs are not limited to laser applications; partially coherent light from LEDs or other light sources can also be modulated.

Diffractive Optics Provided by HOLOEYE

  • Beam Splitters: Fan-out-elements, Pattern Generators
  • Beam Shaping Elements
  • Line Generators, Crosshair Generators
  • Diffractive Lenses (Fresnel Zone Lenses, Lens Arrays, Cylindrical Lenses)
  • Gratings (Amplitude, Phase, Blazed)
  • Random Phase Plates
  • Wave-Front Generators

Beam Splitters

Diffract the original laser beam into a certain number of beams with a specific direction and intenisty.

Fourier Holograms

A special version of Beam Splitters where special patterns, like images, are realised by diffraction in the optical far field.

Beam Shapers

Map a certain phase function onto the laser beam in order to modify its propagation. Classical application is a Top-hat generation.

Diffusers

These elements can be seen as special scattering plates, where the light will be diffused to a certain geometry mostly to generate a homogenious illumination.

 

Furthermore, with the availability of high-performance electrically addressable Spatial Light Modulators (SLM) visions in diffractive optics as well as in other technologies become reachable. SLMs are pixelated microdisplays that allow the implementation of DOE by feeding the display with computer data in real time or in a time time-division multiplexing scheme. This opens fascinating opportunities in micro-technology such as cost-efficient rapid prototyping of DOE or applications like real-time holography and real-time optical tweezers.

Spatial Light Modulator

 


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