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Using the energy acceptance plot

The energy acceptance plot displays a graph of energy captured from an isotropic point source as a function of the angle of incidence of the energy at the image plane. It is useful to see what fraction of the energy will enter a fiber optic at the image plane, as a function of the numerical aperture of the fiber. This is a purely geometrical calculation, and does not take into account energy losses in the lens due to reflections, scattering, or absorption.

To create the energy acceptance plot window:

  1. Select from the menu Analysis > Energy > Acceptance

Exporting data from energy acceptance plot

The underlying data may be exported using the Export toolbar icon, or by "Save data as..." on the contextual menu (obtained by control clicking on the image).

Options panel

Search
Using the Search popup menu, select the method used when searching for the boundary of the pupil. Presently the only option is "Spherical octahedron" for a finite conjugate system or "Hexagon" for an infinite conjugate system. The "Spherical octahedron" option uses a recursive spherical triangulation, starting from a spherical octahedron, to search the entire forward half of the emission sphere of an isotropic emitter to determine the solid angle into which emitted energy must pass in order to reach the indicated surface. The "Hexagon" option uses a recursive planar triangulation in the input plane, starting from a hexagon, to find the area through which emitted energy must pass in order to reach the indicated surface.
Depth
During the search for the boundary of the pupil, triangles are subdivided where they straddle the boundary between captured and lost energy. The recursion depth parameter is the number of subdivisions. Typically 7 will yield a good result.
Min
Before the search, triangles are subdivided to this depth before testing for ray capture. This increases the resolution of the search in the interior of the pupil, but at the cost of much additional ray tracing. Usually this parameter can be left at zero.
Field
Using the Field popup menu, select the field point for which you wish to calculate.
Wave
Using the Wave popup menu, select the wave for which you wish to calculate.
Surface
The surface popup allows you to select a surface that rays much reach to be considered.
Aperture
Using the Aperture popup menu select a ray acceptance criterion. Select "Surface" to use the surface aperture (if there is one). Select "Radius" to use a circular aperture of specified radius (a dialog box will appear where you can enter the radius).
Abscissa
Quantity to use for the horizontal axis of the plot. This is the "numerical aperture" or "transverse momentum" (the two terms are synonymous). This is the product of the image space index of refraction and the sine of the angle between the ray direction and the image surface normal. In other words, the "numerical aperture" of a fiber optic at image surface that would permit the ray to enter.
Ordinate
How to display the accepted energy. Transforms the raw data to various representations. For finite conjugate system, the options are solid angle, fraction of sphere, fraction of hemisphere, or numerical aperture. These refer to the object space.
Color by
Use this popup to indicate how curves will be colored.
Scale only expands
If checked, the scale of the axes only expands due to the action of sliders, etc.
Axis tight on data
If checked, the limits of the axes are chosen so that the data exactly fills the graph. If not checked the limits of the axes are chosen to give "nice" values at the extremes of the axes.

See also