Absolute spektrale Strahldichte eines Strahlers ohne Inversion der Besetzungszahlen im optischen Resonator
The spectral and spatial distribution of radiance from a quasi thermal light source in an optical resonator is studied. It is found that the concept of energetic ray optics is necessary for a complete description of this phenomenon.As the described experiment verifies, the radiance interference maxima exceedes the black body radiance in the range between optically thin and thick layers of the light source. The principle of superposition in interference giving rise to the amplification or diminution of radiance according to the phase angle, agrees with the energy law, only if it is used to the radiance averaged over the phase angle. Kirchhoffs law, which is an energy law, proves therefore to be right only for the radiance thus averaged.A short study of the blackbody cavity containing a resonator has revealed the same result. Concerning the energetic radiation laws, such as Kirchhoffs and Planck's law, the indeterminacy relation has to be taken into account.