Diamond directly reflects hard X-rays

A plot shows absolute reflectivity of 13.9 keV x-rays from the (008) atomic planes of a diamond crystal in Bragg backscattering (top). An x-ray Lang transmission topogram of the diamond crystal illustrates its size (bottom). The diamond crystal is about a millimeter thick. (Figure: Argonne National Laboratory)


Chicago, IL--Argonne National Laboratory researchers have demonstrated that diamond can directly reflect hard x-rays. Via Bragg diffraction, high-quality synthetic diamond crystals can reflect more than 99% of hard x-ray photons at normal incidence with high uniformity across the crystal.1 The discovery should benefit hard x-ray telescopes and physics experiments.

Hard x-rays cam be made to reflect at close to 100% reflectivity from other types of mirrors, but only at grazing-incidence angles (on the order of 89 degrees from the normal or more). This makes for extremely large mirrors and, if focusing is required, very complex optics. Diamond normal-incidence mirrors could make x-ray optics much more like conventional reflective optics.

The researchers used high-brightness x-rays at the at Argonne National Laboratory's Advanced Photon Source. The work was conducted by a team comprising investigators from Argonne National Laboratory and the Technological Institute for Superhard and Novel Carbon Materials (TISNCM) in Russia. This investigation was motivated by the need for high-reflectivity x-ray mirrors at close-to-normal incidence for use in x-ray free-electron-laser oscillators (XFELOs).

XFELOs will provide scientists with fully coherent x-rays that have record-high spectral purity and average brightness, qualities that are highly desirable for experiments. Unlike high-gain x-ray lasers, XFELOs are designed to be low-gain machines, requiring a low-loss optical cavity with high-reflectivity x-ray mirrors close to backscattering, similar to conventional tabletop lasers.

The feasibility of XFELOs was questioned by many experts because of the high-reflectivity x-ray mirror limitations. These limitations are now removed by the new demonstration. Theoretical analysis shows that diamond has the highest (higher than any other crystal) Bragg reflectivity, due to the uniquely small ratio of the extinction length in Bragg diffraction to the absorption length. Even in backscattering, where the reflectivity is lowest, it was thought to be more than 99% -- which has now been demonstrated.

For the experiment, synthetic-diamond single crystals of very high crystal quality were grown at the TISNCM via the temperature-gradient method under high-pressure and high-temperature conditions. The reflectivity measurements were performed at the X-ray Science Division beamlines 30-ID and 7-ID at the APS, using 23.7-keV and 13.9-keV photons, respectively.

The results in this study support a broad range of potential applications of diamond crystals for high-reflectance, coherence-preserving, and resilient x-ray optics such as x-ray monochromators, beamsplitters, delay lines, high-finesse Fabry-Perot resonators, and others.

Source:  Argonne National Laboratory


1. Yuri Shvyd’ko et al., Nature Photonics (published online August 2011); DOI:10.1038/nphoton.2011.197

Most Popular Articles


Durable survivors evolve new forms


Laser Measurements Critical to Successful Additive Manufacturing Processes

Maximizing the stability of the variables going into any manufacturing process is what ensures ts consistency and high quality. Specifically, when a laser is...

Ray Optics Simulations with COMSOL Multiphysics

The Ray Optics Module can be used to simulate electromagnetic wave propagation when the wavelength is much smaller than the smallest geometric entity in the ...

Multichannel Spectroscopy: Technology and Applications

This webcast, sponsored by Hamamatsu, highlights some of the photonic technology used in spectroscopy, and the resulting applications.

Handheld Spectrometers

Spectroscopy is a powerful and versatile tool that traditionally often required a large and bulky instrument. The combination of compact optics and modern pa...
White Papers

Wavelength stabilized multi-kW diode laser systems

Wavelength stabilization of high-power diode laser systems is an important means to increase the ...

Narrow-line fiber-coupled modules for DPAL pumping

A new series of fiber coupled diode laser modules optimized for DPAL pumping is presented, featur...

Accurate LED Source Modeling Using TracePro

Modern optical modeling programs allow product design engineers to create, analyze, and optimize ...
Technical Digests

ADHESIVES, SEALANTS, AND COATINGS: Solutions for optical technologies

A vast array of optical systems of various types and degrees of complexity require the use of adh...

WAVELENGTH-SWEPT LASERS: Dispersion-tuned fiber laser sweeps over a 140 nm range for OCT

By eliminating the use of mechanical tunable filters and instead tuning by intensity-modulation i...

Keeping pace with developments in photonic materials research

For demanding or custom spectroscopy solutions, care must be taken in selecting and integrating a...

HIGH-POWER FIBER LASERS: Working in the kilowatt regime

High-power materials-processing fiber lasers are available in an increasing variety of forms, as ...

Click here to have your products listed in the Laser Focus World Buyers Guide.
Social Activity
Copyright © 2007-2014. PennWell Corporation, Tulsa, OK. All Rights Reserved.PRIVACY POLICY | TERMS AND CONDITIONS