X-rays cannot be used directly as a light source in an X-ray microscope for several reasons:
Wavelength: X-rays have much shorter wavelengths compared to visible light. While visible light has wavelengths in the range of a few hundred nanometers, X-rays have wavelengths in the range of picometers to a few nanometers. The short wavelength of X-rays makes it challenging to manipulate them using conventional optical components like lenses, mirrors, and filters designed for visible light.
Absorption: X-rays are highly penetrating and can easily pass through most materials, including the components of an X-ray microscope. This makes it difficult to confine the X-rays and focus them onto a sample. Additionally, X-rays are absorbed by air, so the microscope needs to be operated in a vacuum or in an environment with controlled gas composition.
Imaging methods: X-ray microscopy typically relies on techniques such as X-ray absorption contrast, phase contrast, or scattering contrast to generate images. These methods involve detecting the interactions between X-rays and the sample. Simply using X-rays as a light source would not provide the necessary contrast or information needed to form detailed images of the sample.
To overcome these challenges, specialized techniques and components are required for X-ray microscopy. X-ray microscopes use X-ray sources such as synchrotrons or X-ray tubes that emit X-rays with controlled properties. They employ X-ray optics such as zone plates or mirrors designed specifically for X-rays to focus and manipulate the X-ray beam. Detectors capable of detecting X-rays are used to capture the X-ray signals interacting with the sample and convert them into images.
By utilizing these dedicated components and techniques, X-ray microscopes can overcome the limitations posed by the unique properties of X-rays and produce detailed images of samples at high resolutions.