application brief AB20 5

replaces AN

1149 5

Secondary Optics Design

Considerations for SuperFlux LEDs

Secondary optics are those optics which exist outside of the LED package, such as reflector

cavities, Fresnel lenses, and pillow lenses. Secondary optics are used to create the desired

appearance and beam pattern of the LED signal lamp.

The following section details the optical characteristics and optical model creation for Lumileds

SuperFlux LEDs. In addition, simple techniques to aid in the design of collimating reflectors,

collimating lenses, and pillow lenses are discussed.

Table of Contents

Optical Characteristics of SuperFlux LEDs

2

LED Light Output

2

SuperFlux LED Radiation Patterns

2

Optical Modeling of SuperFlux LEDs

3

Point Source Optical Model

3

Detailed Optical Models

4

Secondary Optics

5

Pillow Lens Design

9

Design Case—Pillow Design for an LED CHMSL

9

Non symmetric Pillow Lenses

11

Selecting the Size of the Pillow Optic

11

Recommended Pillow Lens Prescriptions

12

Other Diverging Optics

13

Reflector Design

14

Design Case—Reflector for a CHMSL Application

14

Reflector Cavities with Linear Profiles

15

Reflector Cavities with Square and Rectangular Exit Apertures

15

Other Reflector Design Techniques

16

Collimating Lens Design

17

Fresnel Lens Design

18

Design Case—Collimator Lens

19

Other Lens Design Options

19

Appendix 5A

21