Broadband hybrid diffusers are a unique type of beam shaper element that combines the capabilities of diffractive and refractive elements on the same surface. Regular broadband diffusers are basically insensitive to input wavelength as the predominant principle behind their operation is geometrical optics and thus the chromatic dispersion is low. Diffractive diffusers, on the other hand, will have completely different scaling on the output beam and efficiency loss when used in a wavelength that is not their design wavelength, as the phase delay they generate is wavelength-sensitive . A combination of these two elements then can be one in which the large-scale variation is controlled with a component similar to a broadband diffuser such as a micro-lens array. Then, a small scale structure is added to provide a finer control over the divergence angles. An optical component constructed following these guidelines is referred to as a broadband hybrid diffuser.
A hybrid broadband diffuser can be used to generate diffuser beams that have more precise divergence angles. Furthermore, the shape of the output beam will not vary that much with changing wavelength. The addition of the fine structure permits a fine control over the final characteristics of the beam.
In terms of sensitivity of the output beam with alignment errors, the hybrid broadband diffuser can be as tolerant as normal broadband diffusers. This stems from the fact that the main transformation effect is given by geometrical optics.
A hybrid broadband diffuser can be used to generate any desired geometrical shape, just as it is the case with diffractive diffusers. They can also be used to create even more complex output patterns. For instance, in 3D sensing application, a broadband hybrid diffuser can be used to generate an area of uniform illumination but with a subzone that becomes more brightly illuminated. This sort of structured illumination is used to provide a reference for orientation.
There are many applications in which a broadband hybrid diffuser can be used. In fact, all those applications in which a diffractive diffuser or a normal broadband diffuser are currently used may also benefit from a broadband hybrid diffuser. One area is LIDAR or time of flight, which is becoming increasingly popular as autonomous vehicle technology hinges on these sorts of devices. Another relevant application is in cinema projections in which a hybrid broadband diffuser is used to illuminate evenly the imager device. The hybrid broadband diffuser ensures that no colour brightness is lost due to a mismatch of the beam reaching the imager for different wavelengths.
For more information about Broadband Hybrid Diffusers, please visit:
