The final approach -the enclosing box method -was implemented to better mimic the experimental approach commonly used (as in this study) to determine the external photon efficiency, in which the LSC edge is placed at the input to an integrating sphere connected to a spectrometer to measure the intensity and wavelength of output light. To imitate this in simulation, instead of counting all rays exiting from the edges of the device, the device is first enclosed in a box, and all rays exiting from the edges of the enclosing box are counted as output rays. An example of this for a circle LSC is shown in Figure . A subset of the enclosing box method is the enclosing shape method, shown in Figure for a triangle LSC. Instead of enclosing the LSC in a box, the LSC is enclosed in a scaled-up version of itself. This helps to replicate experimental setups where the total edge emission is measured by sequentially pointing individual edges at an integrating sphere and summing the edge emissions to obtain the final output.