- #1
Theraven1982
- 25
- 0
A fresh question.
I want to find the number of photons falling on a pixel in a CCD. A very simple model:
* bigger source area gives larger response ([tex]A_s [/tex])
* when object farther away, smaller response: [tex]\frac{1}{R^2} [/tex]
* bigger detector area gives larger response ([tex]A_d [/tex])
* size of the lens is [tex]\pi r^2 [/tex], with r the radius of the lens
* the larger the focal length, the smaller the amount of light on the detector: [tex]\frac{1}{f^2}[/tex]
* atmospheric damping gives extra coefficient of D
* spectral response dependence: [tex]QE(\lambda)[/tex]
* amount of energy from the source: E
gives something like this:
[tex] A_s A_d\frac{1}{R^2}\int^{\lambda_e}_{\lambda_s} QE(\lambda)E d\lambda[/tex]
If I understand correctly, if this is calculated (the quantum efficiency can be modeled like e.g. 3 small parts), and the answer is divided by the photon energy, the amount of photons per pixel should appear.
I don't really know how to put in the energy from the source. The radiant exitance looks good, but I don't know what to do with it. And I can't find a source of information on how large these quantities should be.
I want to find the number of photons falling on a pixel in a CCD. A very simple model:
* bigger source area gives larger response ([tex]A_s [/tex])
* when object farther away, smaller response: [tex]\frac{1}{R^2} [/tex]
* bigger detector area gives larger response ([tex]A_d [/tex])
* size of the lens is [tex]\pi r^2 [/tex], with r the radius of the lens
* the larger the focal length, the smaller the amount of light on the detector: [tex]\frac{1}{f^2}[/tex]
* atmospheric damping gives extra coefficient of D
* spectral response dependence: [tex]QE(\lambda)[/tex]
* amount of energy from the source: E
gives something like this:
[tex] A_s A_d\frac{1}{R^2}\int^{\lambda_e}_{\lambda_s} QE(\lambda)E d\lambda[/tex]
If I understand correctly, if this is calculated (the quantum efficiency can be modeled like e.g. 3 small parts), and the answer is divided by the photon energy, the amount of photons per pixel should appear.
I don't really know how to put in the energy from the source. The radiant exitance looks good, but I don't know what to do with it. And I can't find a source of information on how large these quantities should be.
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