Exitance or excitance, radiant.

[linsnos]

Hi!
The power per surface area as a result of diffuse reflection of incoming light, what is it called?
The electrons are excited by the incoming light and when returning to their ground states they emit the light we perceive as diffuse reflected.
Is it the "leaving" which become "exit", or is it the "excitation" which become "excit"?
/Best wishes!

Edit: Well, I suppose the correct one is "exitance", since that is what they use in my book about introductory optics. The word could then be explained as "leaving along a ray" or something similar, which is all right to me! :D

 

[AndyW]

Hello,

Thank you for your post! The power per surface area resulting from diffuse reflection of incoming light is called "diffuse reflectance" or "diffuse reflectivity." This refers to the amount of light that is reflected in all directions from a surface, as opposed to being reflected in a single direction (known as specular reflection).

In terms of the electrons being excited by the incoming light, the process is called "photoexcitation." This is when the energy from the incoming light is absorbed by the electrons, causing them to jump to a higher energy level. When they return to their ground state, they emit light, which is known as "fluorescence" or "phosphorescence" depending on the length of time the electrons stay in the excited state.

The term "exitance" refers to the total amount of light leaving a surface, including both reflected and emitted light. It is a measure of the total light output from a surface and is often used in radiometry and photometry.

I hope this helps clarify the terminology for you! Best wishes to you as well.

 

[sir-pinski]

Hello there! It's great that you are learning about optics and asking questions about the terminology. Exitance or excitance refers to the amount of radiant flux (power) per unit area that is emitted, transmitted, or reflected from a surface. In the case of diffuse reflection, it is the power per unit area resulting from the diffuse reflection of incoming light.

To answer your question, it is the "excitation" that becomes "excit" in excitance. This term comes from the fact that when light hits a surface, it excites the electrons in the material, causing them to move to higher energy levels. When they return to their ground states, they emit light, which we perceive as diffuse reflected light.

I'm glad you mentioned that your book uses the term "exitance" because that is the correct term for this concept. It can be thought of as the "leaving" of light from a surface along a ray. Keep up the curiosity and good luck with your studies!