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Invisible forces: Why do regional plates focus X-rays?
A zone plate is a device capable of focusing light or other matter that exhibits wave characteristics. Unlike traditional lenses or curved mirrors, area plates use diffraction instead of refraction or reflection to achieve focusing. The roots of this concept can be traced back to the research of French physicist Augustin-Jean Fresnel, so it is sometimes called a Fourier zone plate.
The focusing power of area plates arises from the Arago spot phenomenon caused by diffraction from an opaque disk.
The structure of a zone plate consists of a set of concentric rings, called Fourier zones, that alternate between opaque and transparent. When light strikes the zone plate, it bypasses the opaque areas and interferes constructively at the set focus position, resulting in a clear image.
This design makes the area plate unique and capable of effective focusing at different wavelengths.
Manufacturing area plates requires precise switching at the radial position of the ring in order to achieve constructive interference. When the miniaturization of the area plate is compared with the focal length, this switching also has its corresponding approximate formula for calculation, which allows engineers to design according to specific application requirements. These designs are usually realized using photolithography technology, and as photolithography technology advances, its resolution continues to improve.
Application fields of regional boards
With the development of science and technology, area plates play an increasingly important role in various fields, especially in physics, photography, gun sights, imaging lenses, etc. Many wavelengths of light are not transmitted transparently through traditional materials such as glass, making area plates an ideal choice.
For example, X-rays are weakly refracted by glass, requiring different techniques to focus them.
Zone plates eliminate the need to find transparent, manufacturable refractive materials for every wavelength, which is critical to shaping the future of scientific research. Likewise, many waves (even matter waves in quantum mechanics) can be focused through area plates, which expands its range of applications.
Breakthrough in photography
In photography, area plates can replace lenses or pinholes to create soft, sparkling images. The transparent area of the area plate is larger. Compared with a pinhole of the same size, its effective aperture value is lower, which helps to reduce the exposure time. Portable photography is becoming more feasible, especially now that high ISO settings on digital SLR cameras allow for greater shooting flexibility.
Diverse applications
Beyond photography, zone plates have been proposed as an affordable sight replacement that can also act as an imaging lens and even operate without reflections. In addition, radio wave therapy can be focused like a parabolic reflector through the reflectively designed zone plates.
Conclusion and Outlook
Area plates are not only a model in the field of optics, but also an indispensable part of today's scientific research. Its development and application have allowed us to see the unlimited potential of future science. Faced with such a technology full of possibilities, in what areas do you think we can further explore the potential of regional boards?
