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Lambertian Plane

 

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Description


The Lambertian Plane type Source Primitive represents an illuminated aperture whose radiance is constant with angle.  The irradiance is uniform within the source aperture and the intensity distribution falls of as cos(Q), where Q is the angle measured from the source's +Z axis.  The total number of rays generated by the source is a combination of the number of starting ray positions, number of ray directions per ray position, and the wavelength method.  Independent control over the spatial sampling of the source aperture and the angular sampling of the emission cone provides the ability for ray generation to be biased to one regime or the other (spatial vs. angular) depending on the application.

 

An example of the source parameter construction and resulting ray trajectories in the visualization view is shown below.

 

Figure 1.  Lambertian Plane parameter settings corresponding to the visualization view in Figure 2.

Figure 2.  Rays emitted from a Lambertian Plane definition whose parameters are given in Figure 1.  The light gray rectangle shows the boundary of the 41x21 rectangular source aperture (semi-widths, source parameters 4-7), which has been (intentionally, for clarity) sparsely sampled with only 5 random starting positions (source parameter 2).  From each of these 5 random starting positions, 10,000 rays are randomly emitted (parameter 3) into an elliptical cone with semi-angles 5o x 11o (parameters 7-9).

 

 

Navigation


This feature can be accessed in the following ways:

Menu > Create > Source Primitive > Lambertian Plane

Right mouse click on the Optical Sources folder, select Create New Source Primitive > Lambertian Plane

Toolbar button:

 

 

Controls


Control

Inputs / Description

Defaults

Logical Parent

Read-only.  Specifies the source's parent node on the tree.

Optical Sources

Name

Name of the source as it will appear on the tree view.

Lambertian Plane N

Description

Description string that will be visible on the tree view.

 

Parameter Attributes

0

Total power emitted by the source.

1.0

1

Physical units of the source power, specified as either Watts or Lumens.  When Lumens are selected, the source wavelength attributes is forced to use the Random according to spectrum option.

Watts

2

Specifies the number of random position samples within the source aperture from which rays will emit into the specified angular range.

42

3

Specifies the number of rays emitting from each random position within the aperture (parameter 2).  The ray directions are randomly selected to sample the specified angular emission range.

1

4

Semi-aperture of the source in the X-axis.

0.5

5

Semi-aperture of the source in the Y-axis.

0.5

6

Shape of the source aperture.  Options are Rectangle/Square or Ellipse/Circle.

Ellipse/Circle

7

X semi-angle of the cone of rays emitting from each point in the source aperture.  Units are degrees.

90

8

Y semi-angle of the cone of rays emitting from each point in the source aperture.  Units are degrees.

90

9

Shape of the angular emission cone leaving each point in the source aperture.  Options are Rectangle/Square or Ellipse/Circle.

Ellipse/Circle

Wavelength Attributes

Single, List or Random according to spectrum

In the following descriptions, N is the number of ray positions in the source aperture (parameter 2) and M is the number of rays emitting from each point (parameter 3).

 

When the Single wavelength option is selected, N*M random rays will be generated at the specified wavelength.

 

When the List wavelength option is selected, N*M random rays will be generated at each of the active wavelengths with non-zero weights specified in the wavelength list.

 

When the Random according to spectrum option is selected, N*M random rays will be generated and each ray will have a unique wavelength whose value is selected by using the designated spectrum as a probability distribution.

Single at the default wavelength

Source Draw Color

If the Single or Random according to spectrum wavelength option is selected, this setting controls the ray position and trajectory draw colors.

 

If the List wavelength option is selected, this setting only controls the ray position draw color. Ray trajectory draw color is controlled by the color specifications in the wavelength List for each wavelength.

 

Polarization

Polarization

If checked, polarization data for the rays is maintained and stored.

Unchecked

Handedness

Sets the handedness of the polarization state (relevant for non-linear polarization states).  If the ray is propagating towards you, the electric field vector rotates in a clockwise direction for Right handedness and counter-clockwise for Left handedness.

 

Note that for linear polarization, the application of Left or Right handedness is arbitrary. The user may find that the UI display switches handedness depending on the angle of the linear polarization state entered, but this will have no impact on the resulting representation of the linear state.

Right

Ellipticity

Sets the ellipticity of the polarization state, 0 represents linear polarization and 1 represents circular.

0

Angle

Sets the angle of the polarization relative to the X axis.

90

 

OK

Accept settings and close dialog box.

 

Cancel

Discard settings and close dialog box.

 

Apply

Accept settings and keep dialog box open.

 

Help

Access this Help page.

 

 

 

Related Topics


Plane Wave (incoherent)

Point Source (incoherent)

Lambertian Surface

Rayfile Source

Random Volume into a sphere

Ray Fan

Solar Source (simple)

Laser Diode (incoherent)

LED (far-field)

Bitmap

 

 

 

 

 

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