illumination system example 2

What is the Objective of a Illumination System Design

The various objective for the illumination system will be described so that you can clearly define the target parameters of your illumination design.

This article provides a discussion and examples off the performance goals of illumination systems. The question of “What makes a good illumination design?” will be unravled through the units and targets that are common in illumination design.

The units of measure of an illumination system

  Radiometric Photopic
Term Symbol Name Units Name Units
Flux Φ Power Watts (W) Luminous flux lumens (lm)
Flux/area E Irradiance W/m² Illuminance lm/m² or lux
Flux/solid angle I Radiant intensity W/sr Luminous intensity lm/sr or candela (cd)
Flux/area⋅solid angle L Radiance W/m²⋅sr Luminance lm/m²⋅sr or cd/m² or nit

Below is a schematic image of the above photometric units. With a visual representation of the units, perhaps it is more intuitive to understand the different units of measure.

Schematic diagram of photometric units

Source: PencilofRays.com

Key performance parameter: Uniformity

Angular uniformity: uniformity over a solid angle

TOF - angular uniformity system

Surface uniformity: uniformity per unit area

Fly-eye for digital projector - surface uniformity systems

Key performance parameter: Throughput and efficiency

Several factors can affect the amount of light passing through the system:

  • The throughput or Étendue
  • Absorption of the optical material
  • Reflectivity of reflective surfaces
  • Fresnel reflection between the optical surfaces

Key performance parameter: Color

The perceived color of light is quantified by its chromaticity. Chromaticity is defined by the International Commission on Illumination or Commission internationale de l’éclairage (CIE), and the color matching functions give us the CIE 1931 chromaticity coordinates.

CIE 1931 colour space

Reference  Source: https://www.zemax.com/