Fresnel Zone Plates

X-rays below 5 keV (<~0.25 nm) are typically classified as soft X-rays, where they are more readily absorbed than higher energy X-rays. Typically, zone plates do not require the same thickness for efficiency and allow for higher resolution imaging.

A range of zone plate options for soft/tender X-Rays are available for specific requirements.

X-Rays above 5-10 keV transition from tender to hard X-Rays where they are better able to penetrate through samples to give better imaging. Hard X-ray Fresnel zone plates require high aspect ratio features to offer sufficient efficiency and resolution for energies above 5 keV. Our current optics give ultra-high resolution for sub 25 nm – 100 nm imaging depending on the required energy. Stacking of hard X-rays (either through double processing or chip alignment) can significantly increase the efficiency of our devices.

A range of zone plate options for hard X-Rays are available for specific requirements.

Zone plate efficiency for binary zone plates requires high aspect ratio structures which can survive high flux imaging systems. The “Oxide Interlock” option creates small interconnecting channels between metal zone of silicon dioxide which is transparent to hard X-rays and does not swell or distort, even when not under vacuum. These have been shown to significantly increase the zone plate efficiency and lifetime.

We offer a range of different materials, all chosen to provide the maximum resolution and efficiency for different energies. We currently offer as different materials for zone plates: Au, Cu, Mo, Ni, W, Pt, and free-standing silicon nitride. To compare the different materials, see our zone plate calculator at www.appliednt.com/zpcalc

Copper zone plate with 250 µm diameter and 80 nm outer zones

SEM image of copper zone plate with 250 µm diameter and 25 nm outer zones

Central stop and outer blocker options significantly improve zone plate imaging, with reduction of the 0^th order and improved lifetime of the optics. Various Thicknesses up to 3 µm on chip are available or >10 µm as a separate chip.

Custom designs and frame sizes can be developed for specific applications. We are able to fabricate devices down to 0.1 mm and below. Our standard frame sizes are 5 mm x 5 mm and membrane thickness can be down to 50 nm while the 100 nm thickness is ideal for energies above 5 keV. We also offer silicon carbide membranes for those requiring long-lifetime membranes.

Our custom XY stage allows micro-scale alignment of a central stop and zone plate and also allows for a possible blast-shield to be mounted. The outer dimensions of the XY stage are 19 mm wide x 19 mm tall x 5.1 mm deep and is made of lightweight aluminum. Threaded M2 screw holes are provided for straightforward attachment to any existing experimental setups.