Why spot and beam uniformity are not always equal

by | LED, optics

For many LED optic projects, a spot size and beam angle can be specified with a single uniformity value. In cases of beam angles above 30 degrees, things get tricky. Please see the images below for an explanation.

If you prefer to understand the math…

Illuminance is changed by formula E=(I/r*r)*cos(A), where E – illuminance, I – luminous intensity, r – distance to spot, A – angle of ray.

Distance r is usually constant. If the dependence of I from A is constant, we have illuminance falloff at high A values because cos (A) multiplier is smaller.

Why spot and beam uniformity are not always equal 1

With beam angles above 30 degrees, it is tricky to specify with a single uniformity value the spot size and beam angle

Why spot and beam uniformity are not always equal 2

Illuminance is dependent on illuminance, luminous intensity, distance to spot, and ray angle.

 

Need assistance designing a custom illumination optic, lens or light pipe? Learn more about our design services here.

Related Posts