Using the GUI, the simulation will return the total external photon efficiency (shortened to optical efficiency (opt. eff.) in the program), as well as the efficiency at each edge of the device (of course, for alternative geometries, the efficiencies at the four cardinal directions have little meaning). In addition, as shown in Figure -f, the GUI also outputs five data plots to help the user assess the quality of the simulation. Figure shows the optical efficiency as the program runs and generates additional rays. This is useful for the user to know if this parameter changes significantly while the program is running or if it is generally stable. Figure shows the convergence plot of the efficiency. Convergence is defined as the difference between each new efficiency value (as rays are added to the simulation) and the average of all previous values. If the convergence value reaches below the threshold (default 10 -3 , user-configurable), the simulation is said to converge, and the simulation automatically stops. Figure shows the distribution of entrance wavelengths superimposed on the input spectrum used, to prove that they match. Figure shows the distribution of exit wavelengths along with the absorption and emission spectra of the luminophore. This is useful to visualize any reabsorption losses caused by the dye, and to ensure that the optical properties of the luminophore were incorporated accurately. Finally, Figure shows the x-and y-positions and wavelengths of the entrance and exit rays, which is a useful qualitative visualization of efficiency (e.g., note the red dots on the device edges) and to ensure the object was correctly detected.