A crystal film with nitrogen vacancy centers is placed in close proximity to a photon emitter. Excitation illumination is produced to cause the nitrogen vacancy centers to produce photoluminescence. Illumination is produced by the photon emitter, which may be near field or far field and which quenches the photoluminescence intensity using an effect known as Stimulated Emission Depletion (STED). The quenching caused by the photon emitter is detected and analyzed to determine characteristics of the photon emitter. The analysis takes into account the characteristic dependence of the STED on the depletion light power, i.e. the photon source, and a spatial distribution of the light intensity. The analysis may be applied to spatially resolved measurements or an integral value of the photoluminescence quenching. The analysis may determine characteristics such as peak power, power scaling factor, and FWHM of the illumination profile of the photon emitter.