Capillary X-ray optics and polycapillary X-ray  optics (Kumakhov X-ray optics) has passed a long way of development from first assembled lenses to modern sub-micron integral micro-lenses

Roentgen optics evolution

The Kumakhov x-ray optics, as it is world-wide known by specialists, is based on the principle of multiple reflections from surfaces directed to an X-ray source to achieve a maximum capture angle. The surfaces are produced to provide the maximum number of X-ray/neutron beam reflections when a fall angle should not exceed some critical value.

Multiple reflections in Kumakhov x-ray optics allow turning a beam through a significant resulting angle of the order of several degrees. This means that, when an angle is less than a critical angle, any X-ray beam inside an empty smooth (glass) tube will be multi-reflected from its inner surfaces creating at its end a “virtual” X-ray source.

This also means that by directing X-ray radiation through a special capillary system one can focus an X-ray beam into a focal spot of different size.

This is how a Kumakhov x-ray optics and lens works and this is the principle that became the basis for development of the first Kumakhov x-ray optics and capillary lens in the middle of the 80th of the 20th century.

In case of X-ray radiation for Kumakhov x-ray capillary optics, direction at the output is parallel to a lens axis, a “half-lens” is created. It converts a beam coming out of a point X-ray source into a quasi-parallel one.

The Kumakhov capillary x-ray half-lenses allow creating big fluxes – parallel, horizontal and vertical – with a cross-section from several mm² to a few tens of sm².

The next stage in x-ray lens production development has been creation of unique poly-capillary lenses which allowed increasing by orders the channel number and significantly widening an operating energy range.

On the basis of this physical principle for x-ray Kumakhov capillary optics, starting from the effect invention about 20 years ago, the Kurchatov Institute of Atomic Power Research laboratory (later the Institute for Roentgen Optics) developed five generations of X-ray optical systems – lenses and half-lenses , which are:

• assembled lens made of single capillaries
• monolith lens made of single capillaries
• assembled lens made of poly-capillaries
• monolith lens made of poly-capillaries
• monolith integral micro-lens which led to first implementation of sub-micron technology created in the IRO

A channel diameter in X-ray capillary optics changed from 1-2 mm in the first case to sub-micron level in the last case. The number of channels in capillary X-ray optics increased from several thousand to several million, moreover the first lens was as long as 1 m and patented sub-micron lenses of the last generation have the length of about 1sm only. A focal in capillary X-ray optics spot size decreased from several mm to several microns.

Why are this invention and its implementation as a roentgen system so important?
What advantages does the Kumakhov capillary x-ray optics provide?
Where and what for is it used?

There are several reasons that make the Kumakhov capillary x-ray optics advantageous as compared with other X-ray methods:

• A big capture angle, that is provided by the Kumakhov X-ray capillary lens and an X-ray tube, increases many times a capture angle of any other x-ray optics;
• Possibility to create in X-ray optics a quasi-parallel beam, horizontal and vertical, and the beam size can differ from several mm² to a few tens of sm²;
• Possibility to create in X-ray optics a focused beam of the diameter from several microns and more or to create a “virtual” source with a linear focus.
• The Kumakhov capillary x-ray optics is the most effective x-ray optics, easily compatible with conventional X-ray tubes having the anode of a final size.

Thus the capillary Kumakhov x-ray optics allows implementing ultra-bright “virtual” sources with big fluxes using optics and conventional X-ray tubes, forming parallel or focused X-ray tubes with the gain of the order of hundreds under low energies as much as 1,5 keV , when the wave length is 8 A and up to one thousand in some cases.