Diffraction Gratings - Forensic Science

Diffraction - The tendency of a wave to spread out in all directions whilst transferring energy

Diffraction Grating - A flat object with regular lines on it that block sections of an advancing wave

• The diffraction grating acts as a wall, in which waves are either blocked or reflected
• The wave has the ability to pass through the gaps, which is where the diffraction occurs
  • Most of the wave continues forward on its path (propagating), whilst some will spread out to other directions
  • For the blocked sections of the wave, some parts are absorbed, whilst some is reflected backwards

Superposition - the displacement of two or more waves from separate sources overlapping

Interference/Interference Pattern - the result of the superposition of waves travelling in different directions

Coherent - waves in which the superposition creates a visible interference pattern, where the have the same frequency, wavelength and phase difference

Reflection - the part of the wave the bounces backwards, creating an interference pattern

Photons - tiny energy particles when light is emitted from/absorbed by matter

Emission Spectra - a spectrum of light that is split, producing coloured lines, each line is for a different frequency