Design of a gradient refractive index phase zone plate for soft x-rays

Area of Science:

• Optics and Photonics
• Materials Science
• X-ray Optics

Background:

• Traditional Fresnel zone plates and pi-radian phase shifting zone plates have limitations in soft x-ray focusing efficiency.
• Developing advanced diffractive optical elements is crucial for improving soft x-ray applications.

Purpose of the Study:

• To design and evaluate a new type of zone plate utilizing radial modulation of refractive indices for soft x-ray applications.
• To determine the focusing efficiency of this novel zone plate compared to existing technologies.

Main Methods:

• A zone plate design based on radial modulation of refractive indices using two materials (titanium and chromium) was developed.
• The concentration of constituent materials was varied radially within each zone pair.
• The design was optimized for a soft x-ray wavelength of 2.74 nm.

Main Results:

• The designed zone plate, composed of optimized titanium and chromium, demonstrated a simulated soft x-ray focusing efficiency of 34% at 2.74 nm.
• This efficiency is 3.4 times higher than that of a standard Fresnel zone plate.
• The new design achieved 1.4 times the efficiency of a pi-radian phase shifting zone plate.

Conclusions:

• The novel zone plate design with radial refractive index modulation offers significantly improved soft x-ray focusing efficiency.
• This advancement holds promise for enhancing the performance of soft x-ray optics and related scientific instruments.