Interference pattern observed in a modern-day replica of Thomas Young's double-slit experiment. Here a coherent beam from a diode laser (635 nm) is incident on two closely-spaced slits (25 micron width, and a 45 micron distance between slits). Light transmitted by the two slits diffracts into the free space and the resulting interference fringes are photographed on a screen. This is a classic demonstration of the wave nature of the light. Characteristic laser speckle causes a grainy appearance of the pattern. Digitally manipulated.