Two point source interference patterns. The interference of two sets of concentric waves of light with the same frequency produce patterns where the illumination is equally distributed. If equal intensity, the light will be evenly distributed across the entire surface, just like light waves from a single direct point source of light. However, what is interesting is what happens when the two point source interference pattern is of different frequencies or intensity, where the overlapping waves of light produce curves or variations in the surface appearance, depending on the observers viewpoint. The best method of explaining this is if we consider too often Objects bobbing up and down with the same frequency at two different points in water. Then the two sets of concentric circular waves will be produced, radiating outwards on the surface of the water.

These concentric waves will interfere with each other as they travel across the surface of the water. This is a simple effective representation to light wave interference. However, unlike water where we can visually control the size and intensity of waves, we cannot see the behavior of light waves and in turn makes it much more difficult to control in design. The key to controlling two point source interference and it's resulting patterns is to understand how to cast light using various frequencies of light to create different colors and illuminations on the surfaces of objects. To find out more on color, frequency and color, please refer to my other course color in design.