Reflection calculator4/16/2023 ![]() It is not even obvious how to calculate the beam direction in that case, where Fresnel equations predict complex angles. Note that you have constant optical intensity along the interface, but not over the cross section of the transmitted beam in the absorbing medium, if it has some angle against normal direction. My question would be: why do Fresnel equations not work properly here?įresnel equations do work, but you need to be more careful calculating the transmitted intensity or power from those. Given a 'p' polarization and a non-zero incidence angle, computing the transmittivity ( t), I get a value of transmittance ( T = | t| 2) which is different from the same transmittance computed as T = 1 − R. I wrote a simple Matlab code to compute the reflectances and transmittances of an air – lossy dielectric (with complex refractive index) interface using the Fresnel equations. ![]() Thank you very much for sharing your knowledge. The reflection coefficient vanishes for p polarization if the angle of incidence is Brewster's angle (here: ≈55.4°).įor the simplest case with normal incidence on the interface, the power reflectivity (which is the modulus squared of the amplitude reflectivity) can be calculated with the following equation: ![]() Power reflectivity of the interface for s and p polarization, if a beam is incident from air onto a medium with refractive index 1.47 (e.g., silica at 1064 nm).įigure 2 shows in an example case how the reflectivity of the interface depends on the angle of incidence and the polarization. The calculations cannot be done in the regime of total internal reflection.Īttention: The buttons do not work, as Javascript is turned off in your browser! Figure 2: After you have modified some values, click a "calc" button to recalculate the field left of it. (must be calculated before calculating the values below!)Įnter input values with units, where appropriate. Calculator for Fresnel Equations Refractive index of medium 1: The power reflection coefficients ( reflectivity or reflectance values) are obtained simply by taking the modulus squared of the corresponding amplitude coefficients.įor the transmissivity, one must add a factor ( n 2 cos θ 2) / ( n 1 cos θ 1) in order to take into account the different propagation angles. The corresponding propagation angles (measured against the normal direction) are θ 1 and θ 2 (see Figure 1).įor example, the amplitude transmission coefficient is t s for s polarization, i.e., if the electric field vector is perpendicular to the plane of incidence. n 1 and n 2 are the refractive indices of the two media. For example, t s is the amplitude transmission coefficient for s polarization the transmitted amplitude is that factor times the incident amplitude in that case (disregarding any phase changes for transmission in the media).
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |