OPT-008 · Wave optics Sample material

Diffraction of light

The Huygens–Fresnel principle, Fresnel zones and the zone plate, diffraction at a circular aperture, disc, edge and slit, Fraunhofer diffraction, the diffraction grating and its dispersion, resolving power, and spectral instruments.

Estimated time: 2 h 10 min 4 activities

Learning objective

Study the Huygens–Fresnel principle and the method of Fresnel zones.
Explain Fresnel diffraction patterns for various obstacles and apertures.
Describe Fraunhofer diffraction at a slit and a grating quantitatively.
Study the characteristics of a diffraction grating and the classification of spectral instruments.

Expected outcomes

Calculates Fresnel zone radii and the number of open zones and predicts the pattern at the centre.
Finds the positions of diffraction minima for a slit and the width of the central maximum.
Calculates grating maxima angles, the highest order, dispersion and resolving power.
Determines a wavelength experimentally with a diffraction grating.

Interactive modelDiffraction by a slit and a grating

Activities

Lecture
Lecture · 55 min · required
Diffraction of light. Diffraction phenomena at various slits and obstacles. Calculating a diffraction grating and its main characteristics.
Practice · 55 min · required
Determination of the wavelength of light with a diffraction grating
Laboratory · 1 h 20 min · optional
Final test
Test · 20 min · required · pass ≥ 70%

Completion conditions

  • Lecture
  • Diffraction of light. Diffraction phenomena at various slits and obstacles. Calculating a diffraction grating and its main characteristics.
  • Final test — at least 70%