# Single Slit And Double Slit Diffraction

### Single Slit And Double Slit Diffraction Pattern

Figure 4.11 Diffraction from a double slit. The purple line with peaks of the same height are from the interference of the waves from two slits; the blue line with one big hump in the middle is the diffraction of waves from within one slit; and the thick red line is the product of the two, which is the pattern observed on the screen. So while a single particle will travel through one particular slit in the double-slit experiment, the so-called 'pilot wave' that influences it will travel through both. The two slit de Broglie-Bohm trajectories were first calculated by Chris Dewdney while working with Chris Philippidis and Basil Hiley at Birkbeck College (London). Young’s double slit experiment breaks a single light beam into two sources. Would the same pattern be obtained for two independent sources of light, such as the headlights of a distant car? Suppose you use the same double slit to perform Young’s double slit experiment in air and then repeat the experiment in water.

 Single slit Double slit Three slits Five slits
 Diffraction and interference Interference only

Under the Fraunhofer conditions, the light curve (intensity vs position) is obtained by multiplying the multiple slit interference expression times the single slit diffraction expression. The multiple slit arrangement is presumed to be constructed from a number of identical slits, each of which provides light distributed according to the single slit diffraction expression. The multiple slit interference typically involves smaller spatial dimensions, and therefore produces light and dark bands superimposed upon the single slit diffraction pattern.

### Single Slit And Double Slit Diffraction

The progression to a larger number of slits shows a pattern of narrowing the high intensity peaks and a relative increase in their peak intensity. This progresses toward the diffraction grating, with a large number of extremely narrow slits. This gives very narrow and very high intensity peaks that are separated widely. Since the positions of the peaks depends upon the wavelength of the light, this gives high resolution in the separation of wavelengths. This makes the diffraction grating like a 'super prism'.

### Single Slit And Double Slit Diffraction

 Show intensity comparison