To see the optical intensity at the detector, we need to open the Detector Viewer by clicking Analysis > Detectors > Detector Viewer.

You will notice that the detector viewer is blank with zero total power, even though we see rays reaching the detector in the layout. The reason is because the rays are traced separately for the layout and for the detector viewer. We need to trace the analysis rays to the detector first to see the result. The number of rays traced to the detector is specified in the “# Analysis Rays” parameter column of the Source Filament object in the editor, which is usually a large number: 5 million in this case. Remember, layout rays do not affect the Detector Viewer results; only analysis rays do.

To trace analysis rays to the detector, open the Detector Control window under Analysis>Detectors>Ray Trace / Detector Control.

Always remember to the clear the detector by pressing  the Clear Detector button, if you do not wish to add the result from the previous trace to the current one. Press Clear Detectors then Trace button followed by Exit.

The detector viewer will display the irradiance distribution, revealing the hotspots caused by the filament source.

If your Detector Viewer looks different, open the detector viewer settings window and make sure the settings are as follows.

You can also see the detector trace result in the NSC Shaded Model Layout by selecting “Color pixels by last analysis” option in the settings.