Waves, Light & Quanta

1. Waves, Light & Quanta Tim Freegarde Web Gallery of Art; National Gallery, London

2. x Young’s double slit diffraction • addition of wave amplitudes • vector electric fields

3. Young’s double slit diffraction x

4. Young’s double slit diffraction x

5.  Young’s double slit diffraction x amplitude intensity

6. Single slit diffraction x

7.  Single slit diffraction amplitude x intensity

8. Huygens’ wave construction • place secondary sources along wavefront Christiaan Huygens (1629-1695) • ...and trigger when wavefront arrives • apply to sinusoidal waves by taking into account the phase with which components arrive • combine by adding the amplitudes • contributions may therefore interfere constructively or destructively

9. Huygens’ wave construction • Fresnel integral • phasors shorter / rotate more quickly at distance to give spiral

10. Cornu (Euler) spiral • Fresnel integral • phasors shorter / rotate more quickly at distance to give spiral

11. Arago’s bright spot • M A Fresnel, La diffraction de la lumière (1818) • S D Poisson: Let parallel light impinge on an opaque disk, the surrounding being perfectly transparent. The disk casts a shadow - of course - but the very centre of the shadow will be bright. Succinctly, there is no darkness anywhere along the central perpendicular behind an opaque disk (except immediately behind the disk). • F Arago: One of your commissioners, M Poisson, had deduced from the integrals reported by [Fresnel] the singular result that the centre of the shadow of an opaque circular screen must, when the rays penetrate there at incidences which are only a little more oblique, be just as illuminated as if the screen did not exist. The consequence has been submitted to the test of direct experiment, and observation has perfectly confirmed the calculation.

12. Diffraction grating x • place secondary sources along wavefront • ...and trigger when wavefront arrives • apply to sinusoidal waves by taking into account the phase with which components arrive INTERFERENCE • combine by adding the amplitudes • contributions may therefore interfere constructively or destructively

13. moosicmountainwild.com Zone plate x • place secondary sources along wavefront • ...and trigger when wavefront arrives • apply to sinusoidal waves by taking into account the phase with which components arrive INTERFERENCE • combine by adding the amplitudes • contributions may therefore interfere constructively or destructively

14. www.sciencebuddies.org Newton’s rings beam-splitter diffuser lens plate • apply to sinusoidal waves by taking into account the phase with which components arrive • combine by adding the amplitudes • contributions may therefore interfere constructively or destructively

15.  Michelson stellar interferometer x intensity

16.     Michelson stellar interferometer

17. Michelson stellar interferometer Mount Wilson Observatory www.mwoa.org