The drawbacks of grazing-incidence reflection gratings are that they are very sensitive to alignment and figure errors, and that they need to be long in the direction of propagation in order to intercept a given mirror aperture. Reflection gratings have the advantage that they can be blazed for higher orders, which increases dispersion, and that diffraction efficiency can be high due to the use of small angles of grazing incidence. X-ray transmission gratings are also very thin and therefore light-weight, and they become highly transparent at higher energies, which allows harder x rays to be collected at the imaging focus by, for example, a microcalorimeter imaging spectrometer. Transmission grating spectrometers have the advantage of being insensitive to grating misalignments and non-flatness. Soft x-ray diffraction gratings fall into two main categories: Transmission gratings and reflection gratings. Most x rays are easily absorbed by matter, which makes it very difficult to manipulate them without high losses, and this is especially true for soft x rays. The SNL recently has concentrated on the development of efficient broad band gratings for the so-called soft x-ray band, ranging from ~ 0.5-10 nm in wavelength. In addition, if the telescope contains a grating spectrometer, x-ray astronomers are generally interested in a fairly broad band of wavelengths, which means that the spectrometer needs to be efficient over the whole band of interest. This demands the lowest possible mass for every component of an astronomy x-ray telescope. X rays are absorbed by the earth’s atmosphere, and therefore x-ray telescopes have to be deployed in space. Many different approaches are used to try to maximize grating efficiency for sub-regions or even specific wavelengths in the x-ray band.įor applications in x-ray astronomy the requirements are even more stringent. The x-ray band is typically considered to cover wavelengths between 0.01 and 10 nanometers, i.e. The SNL has a long history of being a worldwide leader in the fabrication of highly specialized diffraction gratings in advanced applications, mostly related to space science.īoth fabrication and theory of x-ray diffraction gratings are a challenge. This kind of data can provide a wealth of information about the makeup and properties of the emitting object. a star, a molecule), which tells you the intensity of radiation emitted from that object as a function of wavelength. Gratings are often used to generate a spectrum of an object of interest (e.g. The effect is similar to a prism splitting white sunlight into a rainbow of colors, except that diffraction gratings can be applied to many different parts of the electromagnetic spectrum where prisms don’t work. Diffraction gratings are primarily used to diffract waves.
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