This interactive tool helps calculating the illumination angle
of a light source, such as a LED diode, buried within some
support shaping the light beam. A common scenario for such
calculations is the design of light fences, where minimal
inter-beam distance and signal power requirements need to be
estimated for a target distance.
The LED symbol represents the light source. The red
line shaping the beam is the support/burial hole. The cyan arc
is the overall illumination angle, with the yellow measure
showing the span on the target surface. Each green line
shows the signal gain boundary in -0.1db increments.
All calculations are unitless. Click on any field to get extended help.
Source diameter of the illuminator. Zero represents an ideal
point light source, while any non-zero value represents an
Although LEDs are almost ideal point emitters, due to internal
diffusion and imperfect optics they should often be
approximated as small area sources. For an average industrial
5mm round LED, a 1mm diameter is a good approximation.
Source illumination angle, expressed in degrees along the
projected direction. For power calculations, we assume 100%
nominal intensity at the zenith, decaying to zero sinusoidally
to the specified angle.
When looking at LED specs, this should
match the main lobe's total angle in the emission polar plot.
For standard industrial round LEDs, 15° is pretty common.
The burial depth of the light source. This is the distance
from the outer edge of the support to the point light source.
In through-hole LEDs this isn't the tip of the optics
but the location of the anvil within the plastic
casing itself, as represented in the diagram.
Diameter of the tube/hole through which the light should pass through.
Depth of the tube/hole through which the light should pass through.
Distance from the outer edge of the suppport to the projection wall.
Maximal illumination aperture on the projected wall,
irregardless of the actual source emission power.
Maximal illumination angle coming out of the tube/hole,
expressed in degrees.