fibre optic

Huygens Optics explains the Fourier transform and shows how a lens performs one optically. A DLP projector is used as a Fourier filter to do simple pattern recognition on lithographic character patterns.

Huygens Optics shows how DIY photon sieves shape a laser's wave front, explaining how they differ from zone plates and how aperture count affects the focal point, with time-resolved visualizations of the diffraction.

Huygens Optics shows through a laser interference experiment that the question of a photon's size is really about coherence length. It argues that photons exist as energy exchanges between radiation and matter, not as little particles in free space.

Huygens Optics explores the idea that space is a non-linear elastic medium, and uses simulations to show how wave energy might be confined locally into particle-like objects. It touches on inertia, the Schwinger limit and the vacuum as a medium.

Technology Connections explains why brown is not a spectral color but a context-dependent perception, essentially dark orange seen against brighter surroundings.

3Blue1Brown visualizes Feynman's lecture on the refractive index, explaining why light appears to slow down in glass and why the effect depends on color. It builds the idea from waves produced by oscillating charges in the material.

3Blue1Brown explains how holograms record a 3D scene on 2D film, using wave diffraction and phase. The video includes demonstrations of several real holograms.

Richard Feynman, in a clip from the BBC series Fun to Imagine, takes on the puzzle of why mirrors seem to swap left and right but not top and bottom.

Fermilab's Don Lincoln explains why light travels slower in water and glass. He knocks down common wrong explanations such as absorption and re-emission, then gives the wave-mechanics reason tied to refractive index.

Veritasium visits the US Navy's Crane facility to test top night vision goggles. It explains how image intensifier tubes and thermal or digital systems work and compares the generations of the technology.

Professor Mike Merrifield of Nottingham explains in a mostly uncut conversation why light travels slower in glass. He treats light as a wave and describes how the material's electrons produce secondary waves that combine to slow it.

Veritasium revisits Thomas Young's original double slit experiment with light, showing how interference supports the wave nature of light. It uses a pond-wave demonstration to explain the pattern.

Mark Handley of UCL explains, with simulation visualizations, how early Starlink satellites without inter-satellite links could still give low-latency wide-area communication by hopping via ground relays. He shows it can beat fibre on many long paths.