Photometry



A - area $$\left\lbrack m^2\right\rbrack$$

r - distance from source $$\left\lbrack m \right \rbrack$$

$$\Omega$$ - solid angle $$\left \lbrack steradians \right \rbrack$$

$$\Omega=\frac{A}{r^2}$$

$$Q_e$$ - radiant energy $$\left\lbrack J \right \rbrack$$

$$\phi_e$$ - radiant flux $$\left\lbrack W \right \rbrack$$

$$\phi_e=\frac{W_e}{t}$$

$$I_e$$ - radiant intensity $$\left \lbrack \frac{W}{sr} \right \rbrack$$

$$I_e=\frac{\Delta \phi_e}{\Delta \Omega}$$

$$E_e$$ - irradiance $$\left\lbrack \frac{W}{m^2} \right \rbrack $$

$$E_e=\frac{\Delta \phi_e}{A}$$

$$\alpha$$ - angle between the direction to the source and the surface $$\left\lbrack radians\right\rbrack$$

$$E_e=\frac{I_e}{r^2} \cos \alpha$$

$$V$$ - relative spectral sensibility of the human eye

$$V=\frac{\phi_{e_0}}{\phi_e}$$



$$\phi$$ - monocromatic luminous flux $$\lbrack lm \rbrack$$

$$\phi=KV\phi_e$$

$$K$$ - luminous efficacy $$\lbrack \frac{lm}{W} \rbrack$$

$$K=675 \frac{lm}{W}$$

$$I$$ - luminous intensity \lbrack cd \rbrack

$$I=\frac{\Delta \phi}{\Delta \Omega}$$

$$E$$ - illuminance $$\lbrack lux \rbrack$$

$$E=\frac{\Delta \phi}{\Delta A}=\frac{I}{r^2} \cos \alpha$$

$$\eta=\frac{\phi}{P}$$ - luminous efficacy $$\lbrack \frac{lm}{W} \rbrack$$

$$w$$ volumic energy distance

$$w=eE_0^2 \sin \omega t$$

$$ E_0$$ -electric field intensity