Hybrid Transmission Reflection Grating

Technology #11804

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FIG. 1 is a representation of a hybrid transmission-reflection grating according to the concepts of the present invention.FIG. 2 is another representation of a hybrid transmission-reflection grating according to the concepts of the present invention.FIG. 3 is another representation of a hybrid transmission-reflection grating according to the concepts of the present invention.
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Inventors
Professor Mark Schattenburg
Kavli Institute for Astrophysics and Space Research
External Link (snl.mit.edu)
Ralf Heilmann
Kavli Institute for Astrophysics and Space Research
External Link (space.mit.edu)
Managed By
Jim Freedman
MIT Technology Licensing Officer - Chemicals, Instruments, Consumer Products
Patent Protection

Hybrid transmission-reflection grating

US Patent 7,492,989

Applications

This technology is useful for x-ray spectroscopy and a high efficiency beam splitter. It can be also applied to synchrotron optics, medical technology, security technology, crystallography, and many other applications that manipulate x-rays, neutrons, and small particles.

Problem Addressed

Reflection gratings require large size due to their small incident angles (or a grazing-incidence geometry) and they are sensitive to the misalignment or irregularities (non-flatness) in the surface. Also, in transmission gratings, there are problems of high absorption and low efficiency especially at shorter wavelengths as well as difficulties in fabricating those.

Technology

This technology is a hybrid transmission reflection (TR) grating. It is  designed to combine the advantages of transmission and reflection gratings. The TR grating consists of a densely stacked array of thin parallel plates with impinged quantum-mechanical objects at grazing incidence so that it can have enhanced intensity when the direction of reflection and diffraction coincide. Also if the incident angle is no larger than the critical angle of total internal reflection for the given surface, high transmission can be expected as well. The designed structures can be fabricated by using crystalline silicon substrate with an oxide etch stop layer.

Advantages

  • High efficiency (even higher than high efficiency blazed grating)
  • Detector size reduced by a factor of 2 (or twice the dispersion in the same footprint as a traditional transmission grating).
  • Less sensitivity to surface irregularities and misalignment than reflection grating