![]() The form of the diffraction pattern from a single slit mask, of width w, involves the mathematical “sinc function”, where Optical Bench (Click on image to view larger version.) The light on the screen is known as the diffraction pattern. Light from the laser (of wavelength λ) is diffracted by a mask (usually a small aperture or grating) and projected onto the screen, located at a large distance away, such that Fraunhofer geometry applies. Laser diffraction experiments can be conducted using an optical bench, as shown below. This is used in bright and dark field imaging. Since the individual sections (spots) of the diffraction pattern each contain information, by forming an image from only particular parts of the diffraction pattern, the resulting image can be used to enhance particular features. In conventional image formation, a lens focuses the diffracted waves into an image. For a periodic object, the pattern is equivalent to the reciprocal lattice of the object. The symmetry of the pattern can reveal useful information on the symmetry of the mask. The nature of the diffraction pattern depends on the nature of the gap (or mask) which diffracts the original light wave.ĭiffraction patterns can be calculated by from a function representing the mask. If the diffracted light is projected onto a screen some distance away, then interference between the light waves create a distinctive pattern (the diffraction pattern As the gap width approaches the wavelength of the wave, the distortion becomes even more obvious. If the wave passes through a gap, more obvious distortion can be seen. Monochromatic radiation in the visible light range makes it ideal for use in diffraction experiments: the diffracted light forms a clear pattern that is easily measured.Īs light, or any wave, passes a barrier, the waveform is distorted at the boundary edge. ![]() The laser's ability to produce a narrow beam of coherent ![]() Has only become common in the last few decades. Was first documented in 1665 by the Italian Francesco Maria Grimaldi. Whilst a very basic knowledge of the physics of waves and optics is assumed, this teaching and learning package covers the fundamentals of diffraction and imaging. Understand the concepts of the back focal plane and bright and dark field image formation.Be able to relate features of the diffraction pattern to the diffracting object.Be familiar with one-dimensional and two-dimensional diffraction using a laser.Scattering from a pair of infinitely narrow slits. ![]()
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