Photon diffusion happens when photons travelling through a medium undergo repeated scattering events without the photons being absorbed. It can be interpreted as a random walk of photons through the given medium. The question is:
What is then the speed of photon diffusion in a medium with a given density? In other words, how long it takes for the photons to pass through it?
you can see the following links:
1. http://www.nmr.mgh.harvard.edu/PMI/PDF/boas-diss/ch2.pdf
2. https://www.atomic.physics.lu.se/fileadmin/atomfysik/Biophotonics/Education/Tissue_Optics_-_Computer_Exercise_-_Diffusion.pdf
3. https://omlc.org/classroom/ece532/class5/intro.html
4. https://www.osapublishing.org/abstract.cfm?uri=josaa-16-5-1066
The travel time will spread over a broad range. There will be first-arriving photons that underwent no scattering and will show an unaffected phase front behind the scatterer. Later will arrive the photons from every direction that underwent a lot of scattering.
The key evidence for light waves is the Young’s double-slit interference experiment. After the discovery of the double-slit interference experiment of particles (electrons, etc.), the conclusion of light waves can no longer be established. "Wave-particle duality" denies light as particles because of the wave phenomenon, but recognizes the wave nature of particles. It is better understood that light particles have wave phenomena. Of course, light particle behavior and wave mechanism need new understanding.
https://book4you.org/book/18269199/bf2351
The speed of photon diffusion is not a well-defined quantity, as photons do not diffuse in the same way that particles do. Instead, photons interact with the atoms and molecules of the medium through a process called scattering, which causes them to change direction randomly. This means that the photons do not travel in a straight line, and their speed can vary greatly depending on the path they take.
The average speed of photons in a medium is typically much slower than the speed of light in a vacuum. This is because the photons are constantly being scattered by the atoms and molecules of the medium, which slows them down. The exact speed of photon diffusion depends on a number of factors, including the density of the medium, the size of the atoms and molecules, and the wavelength of the light.
In general, the denser the medium, the slower the speed of photon diffusion. This is because there are more atoms and molecules in a denser medium, which means that the photons are more likely to be scattered. The size of the atoms and molecules also affects the speed of photon diffusion. Smaller atoms and molecules scatter photons more easily than larger atoms and molecules. This is because smaller atoms and molecules have a larger surface area, which means that they have more opportunities to interact with the photons.
The wavelength of the light also affects the speed of photon diffusion. Shorter wavelengths of light are scattered more easily than longer wavelengths of light. This is because shorter wavelengths of light have more energy, which means that they are more likely to interact with the atoms and molecules of the medium.
The speed of photon diffusion can be measured experimentally by using a technique called photon correlation spectroscopy. This technique measures the time it takes for photons to travel a certain distance in the medium. The average speed of photon diffusion can then be calculated from this data.
Photon diffusion is a complex process that is not fully understood. However, it is an important process that plays a role in a variety of phenomena, such as light scattering, fluorescence, and non-linear optics.
- Badges
- Science topic