Diffractive optics for wavelengths that refuse ordinary lenses
Fresnel zone plates focus X-rays through constructive interference. They are especially useful when the system needs nanoscale resolution, compact beamline integration, or a focal spot that conventional refractive optics cannot deliver efficiently.
The best configuration depends on the application energy and the target focal length. Materials such as Au, Ni, Ir, Si, and diamond each bring tradeoffs in absorption, fabrication complexity, and diffraction efficiency.
Specification signals to watch
- Outermost zone width, which strongly affects achievable resolution.
- Aspect ratio and material choice, especially for hard X-ray efficiency.
- Substrate, membrane, and alignment requirements for the final instrument.
For synchrotron nanofocusing, X-ray microscopy, and fluorescence mapping, the optic should be specified together with detector, stage, sample, and beam geometry.
