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Spie Press Book

Designing Illumination Optics
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Book Description

This tutorial is written to help engineers tasked with designing illumination optics determine where to start, which methods and approaches to use, and how to gain insight into the nature of the problem at hand. Good illumination design uses patterns from both non-imaging optics (such as compound parabolic concentrators) and imaging optics (such as lenses), often in combination, to produce optimal solutions. These chapters provide readers with a toolbox consisting of a coherent theoretical background, a description of important optical elements and their function, and several design methods. Typical examples are described to illustrate how an experienced optical designer approaches problems, plays with concepts, and arrives at solutions.

"This is a masterful tutorial that not only helps the readers understand the fundamentals in depth but also manages to solve the challenge of teaching how to face illumination design problems."
-Pablo Benitez
Professor, Technical University of Madrid, Spain

"Illumination optics has matured over the last thirty years, but the industry is missing a clear and concise tutorial. Designing Illumination Optics fills that need from the perspective of two authors with both deep insight and an amazing ability to share knowledge."
-Dr. William Cassarly
Senior Scientist of Illumination Engineering, Optical Solutions Group, Synopsys, Inc.

"An excellent introduction to illumination optics from two leaders in the field: practical, accessible, and driven by examples to illustrate key principles. This sorely needed resource provides quickly applicable lessons in illumination optics and builds a strong foundation for more in-depth study. "
-Thomas J. Suleski, PhD
University of North Carolina - Charlotte, Department of Physics and Optical Science

Book Details

Date Published: 13 April 2022
Pages: 142
ISBN: 9781510649354
Volume: TT123

Table of Contents
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Table of Contents

1 Introduction
1.1 Motivation
1.2 One Goal, Many Approaches

2 Preparation
2.1 Modeling, Simulation, and Design
2.2 Phase Space and Etendue
2.3 Edge-Ray Principle
2.4 Radiometry
2.5 Conservation Laws
2.6 Helpful Diagrams
     2.6.1 Light distribution curve
     2.6.2 Phase space diagrams
     2.6.3 Luminance diagrams
     2.6.4 Rayfile analysis—characteristic curve
     2.6.5 Skewness diagrams
2.7 Example Problems
     2.7.1 Museum spotlight
     2.7.2 Reflectorized arc lamp
     2.7.3 LED searchlight
     2.7.4 LED to circular lightguide

3 Illumination Design Process
3.1 Task Types
3.2 Source Aspects
     3.2.1 Predefined source
     3.2.2 Source selection
     3.2.3 Source modeling
3.3 Target or Receiver Aspects
     3.3.1 Standard target
     3.3.2 Target shape
     3.3.3 Prescribed illuminance and intensity distributions
     3.3.4 Target apodization
     3.3.5 Virtual target
     3.3.6 Variable target
3.4 Initial Design Considerations
3.5 Conceptual Design

4 Illumination Design Methods
4.1 Taxonomy by Task or by Etendue
4.2 Point-Source Methods
     4.2.1 Stigmatic designs
     4.2.2 Stigmatic imaging with two or more reflections or refractions
     4.2.3 Point source to prescribed illuminance or intensity distribution: freeform tailoring
4.3 Edge-Ray Methods
     4.3.1 String methods in 2D
     4.3.2 Flow lines in 2D
     4.3.3 Other revolved curves
     4.3.4 Simultaneous multiple surfaces
4.4 Design Methods for Extended Sources
     4.4.1 Conic sections used with extended sources
     4.4.2 Tailored solutions used with extended sources
4.5 Phase-Space Transformation Techniques
     4.5.1 Etendue modification
     4.5.2 Source combination
     4.5.3 Light recycling
4.6 Imaging Optics and Illumination
     4.6.1 Imaging merit function for illumination
     4.6.2 Pupils
     4.6.3 Critical and Kohler illumination
     4.6.4 Kohler illumination as an imaging design method
     4.6.5 Illumination techniques in imaging optics
     4.6.6 Do aberrations increase etendue?
4.7 Optimization in Illumination Design
     4.7.1 Motivation
     4.7.2 Introduction
     4.7.3 Illumination merit function
     4.7.4 Merit function evaluation
     4.7.5 Algorithms
     4.7.6 Parametrization
     4.7.7 Concluding example
4.8 Tolerancing
     4.8.1 Introduction
     4.8.2 Types of tolerances
     4.8.3 Source tolerances
     4.8.4 Tolerancing procedures

5 Design Patterns: Building Blocks for Illumination Systems
5.1 Illumination Systems
5.2 Collimation
5.3 Beam Shaping
5.4 Beam-Delivery Optics

6 Summary





In this tutorial, we assume that you are familiar with basic geometrical (i.e., ray) optics, including Snell's law of refraction, total internal reflection (TIR), first-order imaging optics, and spectra. We also assume that you have some experience in illumination optics. However, even if you are a novice, this tutorial will be useful for you, because it will show you a glimpse of many important design methods and elements with which you must get acquainted. If you are an experienced imaging optics designer, this tutorial will be useful for you, too, because illumination design requires a different way to think about light.

We will mostly ignore diffraction, polarization and coherence; and will consider only homogeneous, isotropic, and linear (HIL) materials - i.e., we will mostly ignore gradient index materials, birefringence, and nonlinear optics. These aspects of physical optics are deep and fascinating, but we have so rarely encountered design tasks where they are important that we are limiting the scope of this tutorial to geometric optics and HIL materials.

Although indeed important for illumination design, we will also not discuss color mixing and homogenization in detail: we refer the reader to our recently published tutorial1 on color mixing.

A growing body of supplementary material, e.g., the optical system files used for the examples, a cosn distribution spreadsheet, and more, is available on our website,

Julius Muschaweck
Henning Rehn
February 2022

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