Apparent emitting characteristics of semi-transparent isothermal medium layer with graded index

By simulating the inside thermal emission of the medium and the radiation t ransfer process. the apparent emitting characteristics of a semi-transparen t medium layer with graded index (GRIN) was investigated. The pseudo-source adding method was combined with the ray splitting and tracing technique in simulation. When constant and linearly distributed refractive indexes were considered for an isothermal layer, the apparent directional and hemispher ical emissivities were both presented and analyzed for different parameters . In addition, the influence of the discrete sub-layer number on the calcul ating was discussed. The results show that the graded refractive index may considerably affect the apparent emission of a semi-transparent medium laye r.