Wave Physics PHYS 2023 Tim Freegarde

2 Wave propagation waves are collective bulk disturbances, in which motion is a delayed response to neighbouring motions the amplitudes are added when propagation follows multiple routes waves propagate via all possible routes

3 Huygens’ wave construction wavefronts propagate from initial disturbance in all directions Christiaan Huygens ( ) each point on the wavefront acts as a secondary source further wavefronts propagate from the secondary sources in the same fashion where wavefronts coincide (strong constructive interference), a new wavefront is formed

4 4 Diffraction S Yoshioka & S Kinoshita, Forma (2002) irridescence of feathers (Grimaldi, 1665)

5 5 Diffraction

6 6 Young’s double slit diffraction x ϑ amplitude intensity

7 7 Single slit diffraction x

8 8 x amplitude intensity ϑ

9 9 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 combine by adding the amplitudes contributions may therefore interfere constructively or destructively INTERFERENCE

10 Diffraction gratings newport.com

11 Diffraction gratings newport.com m=0 m=1 m=2 m=-1 m=-2

12 Phased-array loudspeakers Croke Park, Dublin duran-audio.com AXYS

13 Phased-array radar Fylingdales, Yorkshire 2560 transducers, 25m diameter, MHz

14 Towed array sonar typically 100 hydrophones over 300m 1500 m.s -1 seawater; 1435 m.s -1 freshwater

15 Spatial light modulators 1920 x 1200 pixels, LCD technology 8.1 μm pitch

16 Spatial light modulators 1920 x 1200 pixels, LCD technology 8.1 μm pitch laser tweezing of 2 μm glass spheres in fluid computer-controlled hologram projected and viewed through microscope

17 Michelson interferometer interference by division of amplitude beamsplitterdetector source δxδx

18 Michelson interferometer interference by division of amplitude beamsplitterdetector source δxδxδxδx sodium doublet optique-ingenieur.org chemistry.oregonstate.edu FTIR: Fourier transform infrared

19 Beating TWO DIFFERENT FREQUENCIES

20 Newton’s rings diffuser beam-splitter 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