There is a wide range of different X-ray optics which all share the same goal: a well defined change of the direction of the incoming X-ray light and a controlled influence on the spectrum of the light. All types of X-ray optics can be classified by the physical effect used. The table below shows the effects influencing the direction or the spectrum of X-rays in a controlled way and the optics using these effects:

 

physical effect

types of optics using this effect
reflection (crystal) mirror optics; capillary optics
diffraction zone plates
refraction

compound refractive lenses

absorption windows; filters; pin holes and coded mask telescopes

 

Of course there are many variants of these basic types, listed under the basic types. Each type of optics has its characteristic features, mainly depending on the limitations inherent to the underlying physical effects and those of the manufacturing process. Many optics cover a wide range of applications. Nevertheless it is worth trying to make up a table emphasizing the main individual strengths of the types of optics controlling the direction of X-rays:

 

optics type photon energy
range
working distance
min. focal
spot diameter
imaging or
illumination
achromatic
behaviour

mirror optics

multi layer / crystal mirror optics

0 - 20 keV

0 - 100 keV

>0.1 m

>0.1 m

0.03 µm

0.05 µm

imaging1

imaging1

yes

no

polycapillary optics

mono capillary optics

0 - 20 keV

0 - 20 keV

0.002 - 0.2 m

0 - 0.2 m

1 µm

<1 µm

illumination

imaging1

yes

yes

zone plates 0 - 20 keV 0.001 - 0.1 m 0.015 µm imaging no
compound refractive lenses 5 - 500 keV >0 m 0.1 µm imaging no
coded mask telescopes  all2  -  (10 µm) imaging  yes

1 Good imaging quality is only possible in mirror optics, where each ray undergoes an even number of reflections (only then the Abbé-criterion can be fulfilled approximately)
2 photon energy range mainly depends on the detector

 

These values give a rough estimation and will change with improvements in the fabrication processes.

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