2 PWM Using PWM, the ratio of primarily side emission to primarily forward emission can be adjusted. In the main article three examples show how the image of the beam shape can be modified (Fig 1). Of course, this can also be measured with the spectro-goniometer. In Fig. 7, the angle-dependent spectral radiant intensity (SRI) is presented for different waveforms. From the top-left to the bottom-left the ratio of forward to side emission changes from 100% duty cycle to 0% duty cycle in 20% steps. All the spectra are individually normalized to their maximum value at 0 $^{◦}$. Integrating each of the spectra in Fig. 7 over the wavelength, one obtains the irradiance development shown in Fig. 8. The duty cycle increment here is 10%. Figure 7 | Spectra under AC conditions Changing the duty cycle, the spectra continuously change from forward to side emission. Duty cycle increment is 20%. Figure 8 | Irradiance under AC conditions. Integrating the spectra for different PWM signals over the wavelength gives the irradiance development from forward to side emission for various duty cycles. For comparison the profile of a Lambertian emitter is shown. 3 0 10 20 30 40 50 60 70 80 Angle [ $^{◦}$] 550 650 750 W avele ngth [nm] 0 0.2 0.4 0.6 0.8 1 no rm.SRI 450 t U 0 10 20 30 40 50 60 70 80 Angle [ $^{◦}$] 550 650 750 W avele ngth [nm] 0 0.2 0.4 0.6 0.8 1 no rm.SRI 450 t U 0 10 20 30 40 50 60 70 80 Angle [ $^{◦}$] 550 650 750 W avelength [nm] 0 0.2 0.4 0.6 0.8 1 no rm.SRI 450 t U 0 10 20 30 40 50 60 70 80 Angle [ $^{◦}$] 550 650 750 Wavelength [nm] 0 0.5 1 1.5 2 2.5 norm.SRI 450 3 t U 0 10 20 30 40 50 60 70 80 Angle [ $^{◦}$] 550 650 750 Wavelength [nm] 0 0.5 1 1.5 2 2.5 norm.SRI 450 t U 0 10 20 30 40 50 60 70 80 Angle [ $^{◦}$] 550 650 750 Wavelength [nm] 0 0.2 0.4 0.6 0.8 1 norm.SRI 450 1.2 t U Angle [°] 0 1.2 0.2 0.4 0.6 0.8 1 Norm. irradiance Duty cycle increment: 10% 0 20 40 60 80 Lambertian