Using Diffraction (i.e., Fresnel Zone Plate) to defocus/diverge light

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SUMMARY

This discussion centers on the use of diffraction principles, specifically through Fresnel Zone Plates, to defocus or diverge a collimated laser beam. The original poster notes that while zone plates are typically associated with focusing light, they are interested in exploring their potential for creating a divergent beam, akin to a concave lens. The conversation highlights the need for more phase delay at the center of the lens compared to the edges to achieve divergence, and it opens the floor for examples or solutions that could fulfill this requirement, including nanoscale optics and transformation optics.

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  • Understanding of Fresnel Zone Plates and their optical properties
  • Knowledge of diffraction principles in optics
  • Familiarity with phase delay concepts in lens design
  • Basic grasp of nanoscale optics and metamaterials
NEXT STEPS
  • Research the design and application of Fresnel mirrors for light divergence
  • Explore the principles of transformation optics for creating custom light paths
  • Investigate the use of metamaterials in manipulating light behavior
  • Study the effects of phase delay in lens systems to achieve desired optical outcomes
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Optical engineers, physicists, and researchers in the field of photonics who are interested in advanced light manipulation techniques and applications in both macro and nanoscale optics.

jgk5141
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TL;DR
Is it possible to defocus collimated light using a concept similar to what is found in a zone plate?
I am wondering if it is possible to use principals of diffraction to cause a collimated beam of light (laser) to become divergent. I see that zone plates are most always used for focusing the light from a source, unless they are used in reverse. This is why zone plates are seemingly always compared to convex lenses. However, I have not been able to find anything that uses diffraction for defocusing or diverging the light, which would be comparable to a concave lens. Does anyone know of any examples of what I am looking for?

Note: I am not limiting the scope of my search to geometrical or large scale optics. I am open to looking at nanoscale solutions, such as flat optics, meta surfaces, or transformation optics, as well as any other solutions.
 
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Maybe design a Fresnel mirror which focuses a parallel beam on to a focal point. The light passing between the zone reflectors will then diverge on the same path, as for a concave lens.
 
I have thought about this more and I don't think I am correct. Such a device would have a focal point both sides of the lens. To produce a diverging beam, we need more phase delay at the centre than the edge, and I am not sure how to achieve that. Not sure it is possible,
 

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