Reflection coefficient calculation

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Discussion Overview

The discussion revolves around calculating the reflection coefficient of walls in relation to incident light and its wavelengths, particularly in the context of a room's lighting setup and its application in Lambertian models for optical communication.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant inquires about the calculation of the reflection coefficient of walls when light is incident upon them, specifically considering the wavelengths involved.
  • Another participant references the Fresnel equations as a potential resource for understanding reflection coefficients.
  • A participant clarifies that part of the light is reflected while some is absorbed, particularly noting the use of infrared light as a source.
  • There is a discussion about the necessity of knowing specific properties of the walls and the light source to calculate the reflection coefficient accurately.
  • A participant describes a simulation scenario involving a room with specific dimensions and a ceiling-mounted bulb, indicating a desire to calculate the walls' reflection coefficient for use in a Lambertian formula.
  • Concerns are raised about the insufficiency of room dimensions alone to determine the reflection coefficient, emphasizing the importance of wall material properties.
  • One participant expresses uncertainty about the wall material, suggesting it could be any typical office wall, and seeks clarification on whether obtaining the material's reflection characteristics would yield the reflection coefficient.
  • A separate question is posed regarding the bandwidth of LEDs used in visible communication, questioning whether it is strictly between 400-700 nm or if it could extend into the infrared region, similar to incandescent lamps.

Areas of Agreement / Disagreement

Participants generally agree that specific material properties are crucial for calculating the reflection coefficient, but there is no consensus on how to proceed given the uncertainty about the wall material and its characteristics. Additionally, the question regarding LED bandwidth remains unresolved, with differing views on its range.

Contextual Notes

The discussion highlights limitations in available information, such as the unknown properties of the wall materials and the potential variability in paint characteristics over time. The inquiry into LED bandwidth also reflects uncertainty about the spectral range of different light sources.

kaje
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Hi there,

I am wondering how to calculate the reflection coefficient of walls upon incident light versus wavelengths,,

thanks
 
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Thanks for your reply, i mean part of the light reflected and a part get absorbed as infrared light is used as a source..
 
To calculate knowing what? You need to know something about the wall (and the light) in order to calculate the coefficient of reflection. What is your input data?
 
Hi,thanks for reply, OK, am simulating a system inside a room of (3x3x2.5)m^3 , the only source is a bulb light fixed on the ceiling,so I would like to calculate the reflection coefficient of the walls which then used in Lambertian formula of DC channel gain...
 
The size of the room is not enough information to "calculate" the coefficient of reflection for the walls.
Again, what do you know about the properties of the walls? The reflection depends on the materials on the two sides of the interface. In this case, is probably air and the paint on the wall. But the paint may not even be a homogeneous material. You may be more successful if you look up the reflection for that specific paint. But it will be just a rough estimate, the characteristics of the paint will change in time.
 
thank u so much , actually just a normal room ,but I don't know what material is it? I mean ,it could be any kind of office wall.Do you mean,if I can get the
reflection of the material ,that would be the reflection coefficient...
 
Thanks,I have got another question please, for LED that is used in visible communication, Does the bandwidth sharply be between (400-700)nm or could extend to IR-region like incandescent lamps...

Many thanks
 

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