With a simple lens the Sun’s rays can be focused to a spot strong enough to burn paper.
Focusing visible light is one thing but can you focus X-rays in the same way?
This may seem impossible as X-rays are highly penetrating and they would travel straight through glass without any effect.
However by making several alterations it becomes possible: change the glass lens to one made of beryllium, reduce the diameter of the lens, increase the curvature and make it concave rather than convex then you can begin to see a slight focussing effect. Now stack 100 or more of these beryllium lenses together and you have constructed a device that focusses X-rays.
Throughout an experiment it is often necessary to change the strength of the lens assembly. This can easily be done by adjusting the number of lenses in the assembly. Moreover, it needs to be executed via remote control while ensuring that all the lenses are precisely aligned so that a focussed spot is obtained and finally the assembly must be within a vacuum chamber.
Figure: First image of the video showing X-ray beam (red) being focussed to different distances by the F-switch depending on the location of the sample under investigation.
Credit: Diamond Light Source