Interference Patterns from Two Point Sources Projected on Planes

This Demonstration shows the interference pattern that arises from two coherent point sources, neglecting the inverse square dropoff factor in intensity.

Usually the - plane is visualized; in this Demonstration slices are taken through all three coordinate planes for several wavelengths (displayed in nanometers) and at varying distances from the sources. The red and green dots show the location of the sources. The arrows along the axis show their orientation.

The interference term is calculated by taking a time average over the period of the electric field due to point sources:

,

where .

Here is the wave number (radians/centimeter) and is the angular velocity (radians/second). The plots are rendered in units of centimeters.

The second term is the interference term. We have two point sources separated by a distance along the axis centered at . Without the inverse multiplicative inverse square factor, the interference term is given by

.