Angular Apodization Source Modeling 3280 East Foothill Boulevard

Angular Apodization (Source Modeling) 3280 East Foothill Boulevard Pasadena, California 91107 USA (626) 795 -9101 Fax (626) 795 -0184 e-mail: service@opticalres. com World Wide Web: http: //www. opticalres. com Copyright © 2007 Optical Research Associates

Overview • • Angular apodization basics Coordinate systems File format Selecting the angular range and the source surface(s) • Data orientation and effect of binning • Examples – Rotationally symmetric example – IES Import example Source Angular Apodization, Slide 5 -2

What is Apodization? • The default emission patterns of Light. Tools source models are either Uniform or Lambertian. Apodization allows you to change the default distribution to match the distribution of real sources • Apodization data is defined using an input data file • The data is usually from measured intensity data for a given source – Real sources are not always Uniform or Lambertian Source Angular Apodization, Slide 5 -3

When to Use Angular Apodization? • When the intensity distribution of the source is different from Uniform and Lambertian • You have the measured angular intensity data (usually obtained from a datasheet supplied by the source manufacturer), such as an IES file Measured Intensity Distribution for K 2 LED from Philips Source Angular Apodization, Slide 5 -4

A Closer Look • Angular apodization ONLY defines the distribution at far field. This means that all rays generated from the source in a given direction will have the same “flux” (or magnitude) – Angular apodization alone may not have a complete source definition (a) (b) A simple ray generation example from a surface source. (a) all rays from the source in a given direction have equal magnitude and (b) rays have different magnitude. Both will produce the same intensity. Source Angular Apodization, Slide 5 -5

Apodization File Format • Data is applied to the source using a data file or by direct entry in the grid Example File – File format is ASCII text – Header line must contain Source Angular Apodization, Slide 5 -6 U - Direction V - Direction the word MESH: n m, SPHEREMESH: n m, or POLARMESH: n m, where n x m is the size of the text file – U and V directions correspond to X, Y for spatial apodization and Longitude, Latitude for angular apodization MESH: n m a 11 a 12 a 13 . . . a 1 n a 21 a 22 a 23 . . . a 2 n am 2 am 3 . . . amn . . . am 1

Angular Apodization Coordinate System [Latitude 180] [Longitude 180, Latitude 90] [Longitude 270, Latitude 90] [Longitude 90, Latitude 90] [Latitude 0] [Longitude 0, Latitude 90] Latitudes 0 to 1800 Longitudes 0 to 3600 Coordinate system shown can be “global” or “local” (to the surface) Source Angular Apodization, Slide 5 -7

Coordinate Systems • Two coordinate systems can be used for apodization • Source – Allows you to use the “global” coordinate system for apodization • Surface – Allows you to use the coordinate system of the emitting surface • For example, if the distribution is rotationally symmetric then it is convenient to use the “surface” coordinate system Global Coordinate System Source Angular Apodization, Slide 5 -8 Local Coordinate System

Source/Surface Options • “Surface” option is always the best when you have rotational symmetry • “Source” option works better when the data is asymmetric Rotationally asymmetric – “Source” option is convenient [Longitude 90270], [Latitude 0 -180] Source Angular Apodization, Slide 5 -9 Rotationally symmetric – “Surface” option is convenient [Longitude 0360], [Latitude 0 -90]

Selecting the Convenient Coordinate Range “Surface” coordinate system is usually a hemisphere. The coordinate space is a “Polar” grid. Rotational symmetry is easy to define but asymmetry is harder to define Source Angular Apodization, Slide 5 -10 “Source” coordinate system is closer to a “Cartesian” system around the equator. In this region asymmetry is easier to define but symmetry is harder to define

Selecting the Surface (for Asymmetric Data) “Front. Surface” gives the range [Longitude 0180], [Latitude 0 -180]. Latitudes 50180 are shown in the picture “Top. Surface” gives the range [Longitude 90270], [Latitude 0 -180]. Latitudes 50180 are shown in the picture “Back. Surface” gives the range [Longitude 180360], [Latitude 0 -180]. Latitudes 50180 are shown in the picture Latitude 130 Latitude 50 All coordinate values shown are with respect to the “global” (or “source”) coordinate system Source Angular Apodization, Slide 5 -11

Coordinate System Example • An apodization file with angular bounds [Latitude 0 -90], [Longitude 0 -360]. No rotational symmetry Cartesian and Polar illustration of the data; variation in Latitude and Longitude directions. Green cells in the table shows the “center coordinates of each bin”. Source Angular Apodization, Slide 5 -12

Data Orientation • Data is aligned with the local coordinate system of the surface Latitude = 0 Longitude 180 Longitude = 90 Longitude = 270 Latitude = 90 Longitude = 0 Source Angular Apodization, Slide 5 -13

Bin Size First “column” (Latitudes) located at 2. 370 Latitude = 0 Longitude 180 Longitude = 90 Longitude = 270 Latitude = 90 First “row” (Longitudes) located at 16. 360 Source Angular Apodization, Slide 5 -14 Longitude = 0

Example 1 • LED example: HP HSMx-C 650 Surface Mount LED – Rotational symmetry – Any surface of a source is easier to use Source Angular Apodization, Slide 5 -15

Example 1 – Data Input File Min Value, Max Latitude (“South Pole”) 100 degrees latitude Max Value Min Latitude (“North Pole”) Source Angular Apodization, Slide 5 -16 Note that the LED intensity distribution is rotationally symmetric. Therefore, only one column of data is required to specify the variation in Latitude

Example 1 – Data Orientation +X +Y Data is rotationally symmetric. Latitude values are duplicated (interpolation) around longitude angles. Picture above is only for illustrative purposes Source Angular Apodization, Slide 5 -17 Resulting intensity distribution using the 3 D Raster Chart and a Polar Line Grid in the 3 D View. Latitude bins=19, Longitude buns=29

Example 2 • Importing angular data from an IES file (hypothetical data is shown) – Use the IES Read utility to create an apodization file Polar wire grid illustration of the IES data using the “Source” (or global) coordinate system Source Angular Apodization, Slide 5 -18

Apodization Data • This particular IES file has 171 horizontal angles and 171 vertical angles Note: The IES utility shown here is the latest version. Please request a copy if you like to try it. Source Angular Apodization, Slide 5 -19

Example 2 – Data Orientation Resulting intensity distribution using the 3 D Raster Chart and a Polar Line Grid in the 3 D View. Latitude bins=41, Longitude buns=41 Source Angular Apodization, Slide 5 -20

Conclusion • Angular apodization provides you a flexible and fast method to create a wide variety of source models using their measured (or known) intensity distribution in Light. Tools Thanks you for your valuable time and support for ORA products! Source Angular Apodization, Slide 5 -21