X-ray Interferometers Could Become 100 Times Faster

An X-ray interferometer is a device that uses the diffraction of light to measure certain properties of an object through indirect methods, meaning that two beams of light are compared to determine the differences between them, in order to obtain the result. X-ray interferometers are somehow similar to the neutron interferometer, which like the photons also present strong particles-wave duality. Both are built by carving silicons semiconductors about 10 to 30 centimeters in diameter, and 20 to 60 centimeters in length.

Such devices can measure lengths in the millimeter range, with a resolution of less than one nanometer. However, due to their low translation velocity, they are highly unpractical. Recent research might improve the translation velocity by over a hundred times, by using the temporal correlation of the singly interfering X-ray photons.

Although being able to measure lengths in the millimeter range, with nanometer resolution, the measurement process still depends mostly on the high-purity silicon crystal, used as some kind of scale. However, determining lengths in the ranges of sub-micrometers is extremely difficult, due to the fact that this specific length is comparable to the lattice arrangement of the crystal silicon.

Measurements of such small lengths represent a critical aspect for many applications, thus, translation velocities greater than 1 to 10 nanometer per second are needed. These low speeds are mostly generated by the filtering process of the X-ray light, in order to reduce the intensity of the light beam inside the laboratories, which also determines a loss in contrasts, therefore a low measuring resolution.

To be more precise, the light beam is not dense enough for the small numbers of photons to interact with each other and produce the interference effect. To remove this problem, scientists started wonder what would happen if a singly interfering photon would be used, as single photons following their temporal impact on the detector would lead to a continuous signal whose period can be precisely determined.

The quantum-mechanical effect involves determining the frequency at which the crystal period was passed, with the help of a Fourier transformation. This way, shorter measuring times can be obtained, by using constant velocity, which enables the possibility of reconstructing the path of the photons, in similar ways to the classic methods.

By doing so, translation velocities reaching 1000 nanometers per second could improve the measurements made on the crystal lattices and lengths in nanotechnology.