Diffractive Optical Elements (DOE)

What are DOE’s

Diffractive Optical Elements (DOE’s) are thin optical microstructured components designed to utilize light propagation physics to create a desired light pattern, by “encoding” phase information in the beam. This phase distribution leads to constructive and destructive self-interference, forming the pattern at the required distance. Contrary to LED-based, mask-type pattern-forming devices which have inherent optical power loss, DOE uses light physics to redirect intensity from where it’s not required to where it is, therefore minimizing power losses. A DOE can also be designed to act as a lens, or function as a lens combined with pattern generator.

 

Capabilities and limitations

  • DOE’s are designed for a specific wavelength, and can function within a certain spectral range around it.
  • The angular span a DOE can project can reach above 90 degrees.
  • A DOE can be designed to project to a large distance (tens of cm and above) or a finite distance (few mm). The pattern would appear sharp within a range of distances around the nominal distance (focal plane).
  • A single DOE can also be designed to project patterns at objects located at different distances or inclined planes.

Light sources

DOE’s are designed to work with coherent light sources, commonly with edge-emitting laser diodes and VCSELs. Some DOE’s are designed to have a collimated beam as input, therefore there would be some optics between light source and DOE. Some DOE’s are positioned directly after light source, e.g. edge-emitter laser chip or VCSEL chip.

Tilted projection

A DOE pattern projector is designed to deliver a sharp pattern over a range of distances. For certain applications, such as keyboard projection, it is advantageous to design the DOE to project onto a tilted plane.

Oblique-angle projection

In some applications such as automotive, it is required to project the pattern at an oblique angle.

Multi-plane projection

It is also possible to design a DOE to project multiple patterns, each focused to different distance.

Custom DOE

A custom DOE can be developed according to your requirements and pattern topology.

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