Release from Symmetry Axis
Use the Release from Symmetry Axis node to release rays from specified edges along the axis of symmetry in a 2D axisymmetric geometry. It functions like the Release from Boundary node, except that it can only be applied to the axis of symmetry and that the options in the Ray Direction Vector section are slightly different.
See Release for information on the following sections: Release Times, Initial Ray Frequency, Vacuum Wavelength, Initial Phase, Initial Intensity, Initial Radii of Curvature, Total Source Power, Initial Polarization, and Initial Value of Auxiliary Dependent Variables.
Initial Position
Select an Initial position: Uniform distribution (the default), Mesh based, or Density. Mesh based and Density have the same settings as described for the Release node.
If Uniform distribution is selected, enter the Number of rays per release N (dimensionless). The default is 100. The set of the selected boundaries is divided into N segments of approximately equal length, with one ray at the middle of each segment.
Ray Direction Vector
Select an option from the Ray direction vector list: Expression (the default), Spherical, or Conical.
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For Expression a single ray is released in the specified direction. Enter the radial and axial components of the Ray direction vector L0 (dimensionless).
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For Spherical a number of rays are released at each point, from the negative z direction to the positive z direction in the half plane with r > 0. These rays are sampled from an anisotropic hemispherical distribution in wave vector space, so that rays are more heavily weighted toward the r direction rather than the ±z directions. In 3D this would correspond to a spherical distribution of rays such that each ray subtends approximately the same solid angle in wave vector space.
Enter the Number of rays in wave vector space Nw (dimensionless). The default is 50. Then enter coordinates for the Hemisphere axis r based on space dimension. Select the Specify tangential and normal vector components check box to specify the hemisphere axis using a coordinate system based on the directions tangential and normal to the surface (t1, t2, n).
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For Conical a number of rays are released at each point, sampled from a conical distribution in wave vector space. Enter the Number of rays in wave vector space Nw (dimensionless). The default is 50. Then enter coordinates for the Cone axis r based on space dimension. Then enter the Cone angle α (SI unit: rad). The default is π/3 radians. Unlike the Spherical distribution, the rays in the Conical distribution each subtend the same angle in 2D, not the same solid angle in 3D.
For Hemispherical and Conical, select an option from the Sampling from Distribution list: Deterministic (the default) or Random. If Deterministic is selected, the initial ray direction vectors are computed using the same algorithm, which seeks to distribute the rays as evenly as possible in wave vector space, whenever the study is run. If Random is selected, the initial direction of each ray is sampled from a probability distribution in wave vector space using pseudo-random numbers.