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Reflection at an interface

The simulation below shows the waves in the plane of incidence. The incident beam comes down from the top left, the reflected beam goes out the top right, and the transmitted beam continues downwards. The user has control over the refractive indices on each side of the interface, the angle of incidence, and the field strength of each polarisation. The last two sliders select the parallel and perpendicular field strengths by changing the intensity of the incident beam and the angle that the beam is polarised (with zero meaning that the beam is fully p polarised). The electric field strengths and intensities are calculated for each of the transmitted and reflected beams for each of the two polarisations.

To begin using the simulation, select the preset 'Air-Glass Both' configuration and tick the 'Plot intensities' box; the graphs show reflected and transmitted intensities for all angles. In this representation the s (or perpendicular) polarisation is out of the screen. Its strength is represented by a circle for out of the screen and cross for into the screen; completely black is a maximum and completely white is zero. A good way to remember this is to think of an arrow - coming out of the screen is the pointed end of the arrow, while going into the screen, the arrow appears as a cross due to tail feathers. The simulation restricts the polarisation to be out of the screen. The p (or parallel) polarisation is represented by arrow around pointing down and left on the incident beam. there is also an arrow representing the direction of propagation. Change the strengths of the parallel and perpendicular E-field components distinguishes the two components. Next, change the angle of incidence - note that the intensity of the s (perpendicular) component of the reflected beam (represented by a cross for the reflected beam) increases with angle. Give some thought to how the p polarisation changes in this case.

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Simulation by Isaac Lenton, 2017