Fluorescence Properties

Fluorescence Ray Trace

A fluorescence ray trace is done in two stages:

Stage 1 of the ray trace

Stage 2 of the ray trace

Create Model

Ray trace light that illuminates fluorescent material

Calculate Fluorescence &

Create Fluorescent Source Files

Ray trace light emanating from fluorescent material

Perform Analyses

FIGURE 3.8 - Fluorescence ray trace involves two stages

Stage 1: Initial rays are traced in the TracePro model. Any source wavelengths (that also happen to be within the excitation band of fluorescent materials in the model) will be involved in the fluorescence calculation. Note that any wavelengths defined with the selection of Fluorescence emission wavebands will not be valid for the excitation of fluorescent materials in TracePro. The end result of this stage of the ray trace is that source files containing fluorescent ray data are created.

Stage 2: Fluorescent rays are traced from the previously generated source files at the mid-points of the Fluorescence emission wavebands defined for each fluorescing object in the Fluorescence tab of the Apply Properties dialog box. Note

that for the highest waveband (λN to ∞ ), where the mid-point is ill defined, the

fluorescence wavelength is two times the lowest wavelength in the waveband, i.e.

λ = 2λN .

Figure 3.9 illustrates how property and ray trace data are used in each step of the fluorescence modeling process.

TracePro 5.0 User’s Manual

3.15

Defining Properties

FIGURE 3.9 - Process to perform Fluorescence simulation in TracePro.

Raytrace Options

Fluorescence Option

You can enable the calculation of fluorescent rays via a checkbox in the Raytrace|Raytrace Options dialog, Options tab. After the Fluorescence option is checked, there are related options:

There is a drop-down list with two choices:

Immediately trace emission wavelengths - At the conclusion of the excitation ray-trace, the emission ray-trace will automatically begin, so that emission rays are “mixed in” with excitation rays. All irradiance map features, candela plots, flux report, etc. will report the fluorescence emission ray results along with the excitation ray results.

Generate emission source only - At the conclusion of the excitation ray-trace, the emission ray files are generated, but the emission rays will not be traced. You can trace them later at your discretion, by:

a.inserting the emission source file(s) into the model (or any model you choose)

b.disabling any other sources in the Source Tree or Source/Wavelength Selector (or modifying any surface sources in the model to have zero rays, or simply removing the source property altogether)

c.unchecking the Fluorescence option in the Raytrace Options dialog box

d.initiating a raytrace.

Insert file source - During the fluorescence raytrace, TracePro will generate ray launch positions and angles to simulate fluorescence emission. These generated rays are stored in source files to be used during the emission part of the raytrace. This option is used to automatically include the generated source files into the model.

3.16	TracePro 5.0 User’s Manual