5/28/2023 0 Comments Reflection calculator![]() ![]() However the layer thickness can simply be reduced to compensate for the phase angle of r23 and this will provide an ideal zero reflectivity condition. Therefore the phase delay introduced by the (summed) return reflections in the layer will not cancel for the usual "quarter wavelength normal to layer" condition. (for an absorbing substrate), the phase of r23 will not be zero (or 180°). The magnitudes of r12 and r23 are equal (for the lossless case at normal incidence, that index is simply the geometric mean of N1 and N3). ![]() For most values of N3, we can find a real index N2 so that Where r12 and r23 are the Fresnel interface complex reflection coefficients for the respective interfaces. It is easy to see that there is a solution for a lossless coating with zero reflectance value even with a lossy substrate by inspecting the general 3 region Get R13 solves for the reflection for the N1/N3 interface alone by setting the layer thickness to zero, h=0: Get R solves for the 3 region reflectance. If the incident medium n1 is lossy, meaningful R, T power reflectance values with (R + T )= 1 cannot be defined in terms of power in an incident and reflected wave (Macleod 1986). The exact analytical expressions discussed below were used:įor comparison purposes, the calculator below can be used to compute reflectance and transmittanceįor any single-layer and substrate indices and layer thickness h, including losses in N2 and N3. The calculator below solves for the S and P polarization AR coating values N2, T2 with loss in N3. The second solution (lower line) has a value that is less than both N1 and N3 if the incident angle is less than the Brewster angle for the N1/N3 interface, and hasĪ value between N1 and N3 if θ is greater the Brewster angle. The first N2 solution (upper line) always has a value between N1 and N3. The layer thickness is 1/4 optical wavelength in N2 NORMAL to the layer. The results reduce to the well-known N2 = Sqrt(N1*N3) and a layer thickness of 1/4 optical wavelength in N2. The layer refractive index N2 and thickness T2 are different for TE (s pol) and TM (p pol) cases except for normal incidence θ=0. The calculator below can be used to determine the refractive indices N2s, N2p and thicknesses T2s, T2p, for S and P polarizations respectively, yielding zero plane wave reflectance for a single layer coating with an arbitrary angle of incidence in N1Īnd a substrate medium N3. Synthesis calculators are provided for computing the AR coating layer index N2 and thickness T2 and The incident medium N1 and the AR coating layer N2 areĪssumed lossless. This note discusses the single-layer antireflection (AR) coating for arbitrary angles of incidence. ![]()
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