How are holograms possible?
Why Hacker News recommends it
HN commenters call it the best explanation of how holograms work, and one says it transformed their understanding.
What it is
3Blue1Brown explains how holograms record a 3D scene on 2D film, using wave diffraction and phase. The video includes demonstrations of several real holograms.
Recommended by 3 HN commenters across 3 different months, 2024 to 2025.
What Hacker News said
Strong rec omneity · 2025-09 · on “Hololuminescent Display”
On this very topic, this might be one of my most favorite videos ever single-handedly changing my understanding of holograms: [this video]
Recommends injidup · 2024-10 · on “The Physics of Magic Windows (2021)”
Not to take away the brilliance of what is achieved but I think hologram is the wrong word. This is purely about caustics. Amplitude engineering rather than phase. The calculations are just assuming light as particle, not light as wave. A true hologram uses diffraction grating effects and the phase difference from light. There was a very nice explanation on three-blue-brown recently. [this video] I don't think there are any phase effects in the parent attached? Or are there?
Recommends aeonik · 2025-04 · on “Raspberry Pi Lidar Scanner”
Yea I have some ideas, but I haven't found an easy way to implement it yet. The term of art that I'm exploring is called "Holographic Interferometry". Sibling poster gave you a link to regular interferometry. But basically, if you split the laser beam, one goes straight into the camera sensor, and the other off your object, you can do some pretty amazing things. Depending on a lot of little details (The devil is hiding here). I found 3Blue1Brown's explanation to be the best, but less "ready to use". [this video]