Direction Apodization - Lambertian in a given direction

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Lambertian in a Given Direction

Page Contents

Description

Description

The Lambertian in a Given Direction apodization type scales all source rays by their direction to give a Lambertian intensity distribution. This effectively apodizes the rays with a cos(f) factor, where f is the elevation angle in polar coordinates. The following images show the source and intensity distribution for an isotropic plane of random rays emitting into a 90^ocone half angle with the Lambertian in a Given Direction apodization applied.

Navigation

The Lambertian in a Given Direction directional apodization is available on the Power tab of a Detailed Source dialog. From the Power tab, select "Lambertian in a Given Direction" from the drop down menu of directional apodization types.

Controls

The following table describes the available controls on the Power tab of a Detailed Source dialog. Of interest to this help topic are the Direction Apodization parameter settings.

Control	Inputs / Description	Defaults
Total Power	The total power of the source after both the position and direction apodization functions have been applied to the rays.	1
Position Apodization
Type	Drop down menu of available position apodization options.	Uniform
Parameters	Dependent on selected Type.
Direction Apodization
Type	Drop down menu of available direction apodization options. Select "Lambertian in a given direction" from the drop down menu.	Uniform
Parameters
X	X component of the direction cosine vector for the direction about which the apodization is applied.	0
Y	Y component of the direction cosine vector for the direction about which the apodization is applied.	0
Z	Z component of the direction cosine vector for the direction about which the apodization is applied.	1

OK	Accept settings and close the dialog box.
Cancel	Discard settings and close the dialog box.
Apply	Apply settings and keep the dialog box open.
Help	Access this Help page.

Application Notes

Generating a Lambertian distribution

Using the Lambertian in a Given Direction apodization is radiometrically equivalent to selecting a Uniform Direction apodization and setting the source rays to be Lambertian on the Positions / Directions tab of the source dialog. Although these two methods of generating a Lambertian source are radiometrically equivalent, they are represented by different distributions of rays. The Lambertian option on the Positions / Directions page distributes the rays equally in direction cosine space and the Isotropic option on the Positions / Directions page distributes the rays equally in angle space.