Language
Country/Area
No result found
X-rays versus visible light: Why can't we focus X-rays with ordinary lenses?
X-ray technology is a growing and popular field in scientific research, covering diverse applications from materials research to biomedical imaging. However, X-rays face significant challenges in focusing and manipulation when faced with visible light, which is familiar in daily life. This stems from the very different ways in which they interact with matter.
X-rays and visible light are both electromagnetic waves, but because the frequency and particle energy of X-rays are higher, their interaction with matter is not as simple as that of visible light.
Visible light can be easily directed and focused through lenses and mirrors. X-rays, however, are more likely to penetrate and eventually be absorbed by the material, barely changing direction. Therefore, ordinary lenses are not suitable for focusing X-rays. So, what methods are there to redirect X-rays and focus them?
Overview of X-ray Technology
There are various techniques for changing the direction of X-rays, mostly by making small adjustments to the angle. Many X-ray techniques take advantage of estimated angles of reflection, especially at small angles, to achieve focusing. These technologies include:
- Total external reflection technology
- Microscope with multi-layer coating
- Bragg reflection technology
Even in the case of reflection, the cooling, splitting and focusing of X-rays are based on specific interactions with matter.
Challenges of focused optics
In many analytical X-ray techniques, such as X-ray crystallography and small-angle X-ray scattering, it is important to irradiate samples with high-intensity X-rays. This often requires the use of multiple focusing optics to redirect the X-ray beam.
Polymer tube optics
A polymer tube lens is an array of small hollow glass tubes that guides X-rays through multiple total external reflections. Although such optics are achromatic, they can only image small spots of the light source.
Regional Board
Zone plates consist of concentric areas of phase-influencing material or absorbing material whose width is designed to cause the transmitted waves to constructively interfere at a point, thereby achieving a focusing effect.
Combined refractive lens
Because the refractive index of X-rays is very close to 1, the focal length of ordinary lenses becomes impractical, so it is necessary to use lenses with very small radii of curvature and stack them in long rows to increase focusing power.
Reflection and Diffraction
Reflection and diffraction are two key methods of manipulating X-rays. In terms of reflection, X-rays reflected at specific angles can be accurately measured, while diffraction can be used to understand the electron density distribution inside the crystal.
The technique of X-ray diffraction can reveal the arrangement of atoms and other physical properties in crystal structures.
These high-tech technologies are not as direct and simple as visible light focusing, but they are crucial to the advancement of scientific research. Advances in technology have made X-rays more common in many practical applications, including medical imaging, and have improved the contrast and resolution of images.
Future Development
Although early advances in X-ray optics technology have shown great potential, there are still many challenges to overcome, such as improving the efficiency of the equipment and reducing costs. Many researchers are working on applying these emerging technologies in clinical medicine, especially in improving the contrast and resolution of mammography images.
As X-ray technology continues to advance, will it become an important tool for us to diagnose and treat diseases in the near future?
