A parallel beam of light falls normally onto an opaque screen in which two parallel identical slits are made. Light wavelength L = 0.5 µm. The distance between the slits is d = 50 µm. Behind the screen there is a collecting lens with a focal length f = 20 cm so that its optical axis is perpendicular to the plane of the screen and passes through the middle of the gap between the slits. Determine the width of the central diffraction maximum observed in the focal plane of the lens (Fig.).

Detailed solution. Format gif