Light Physics
Effects #
Ray Optics #
- Treat light as rays
- Photons propagating instantly along straight lined
- Light rays don’t influence each other
- Only light-matter interaction chanes the light direction
Units #
Radient energy #
-
The energy
of all the photons in a “stream” -
Measured in Joule
Radient Power #
The radiant energy 
over some period of time, measured in Watt
Irradiance #
“Bestrahlungsstärke”
Total amount of energy that strikes a differential surface in 
.
Computing the Irradiance from the Radiance #
Radial Exitance #
Total amount of energy leaving a differential surface in .
Radiant Intensity #
“Strahlungsintensität”
Amount of Power emitted by a light-source into a certain direction.
Solid Angle #
A solid angle (symbol: 
) is a measure of the amount of the field of
view from some particular point that a given object covers. The unit is the
Steradian
.
Steradian #
The unit for solid angles
, goes from 0 to 
(the full surface area
of the unit sphere).
Radiance #
“Strahldichte”
Radiance measure “intensity” of light along a single ray.
Where 
calculates 
(Area Foreshortening
)
Reflectance #
