Fourier Optics used for Optical Pattern Recognition
Why Hacker News recommends it
Recommended as one of the best explanations of Fourier transforms and a clear demo of analog optical computing.
What it is
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.
Recommended by 5 HN commenters across 5 different months, 2021 to 2025.
What Hacker News said
Strong rec jstrieb · 2021-09 · on “Moiré No More”
I was introduced to this idea in a really cool video about using Fourier Optics for optical pattern recognition.[0] The video happens to have one of the best explanations of Fourier transforms I've yet encountered. [0] [this video]
Strong rec orlp · 2022-06 · on “Photonic Chip Performs Image Recognition at the Speed of Light”
For a somewhat related topic (analog image recognition), for those interested, I can highly recommend this video: [this video]
Strong rec jstrieb · 2022-08 · on “AI-designed camera only records objects of interest while being blind to others”
Reminds me of this really cool video about using Fourier Optics for optical pattern recognition.[1] The video happens to have one of the best explanations of Fourier transforms I've yet encountered. 1: [this video]
Recommends ulnarkressty · 2022-06 · on “Physicists are building neural networks out of vibrations, voltages and lasers”
An even better one - holding an image at the focal point of a lens produces its Fourier transform at the focal point on the other side of the lens[0]. It is used for "analog" pattern matching[1]. There is an interesting video explaining this on the Huygen Optics Youtube channel[2]. [0] - [LINK] [1] - [LINK] [2] - [this video]
Recommends CamperBob2 · 2024-05 · on “AI Needs Enormous Computing Power. Could Light-Based Chips Help?”
You could think of a lens as a "Fourier transformer," not in the LLM sense directly but in the sense of something that executes a Fourier transform. See the excellent videos by Huygens Optics including this one: [this video] entitled "Fourier optics used for optical pattern recognition." Having established that, well, it's not hard to imagine that something that's good at running Fourier transforms is probably good for other situations where you need to run a lot of dot products in parallel. That, in turn, should sound like an awfully familiar problem...
Recommends infogulch · 2025-01 · on “Detecting edges of images at the speed of light”
Huygens Optics has a great video "Fourier Optics used for Optical Pattern Recognition". He starts with explaining the Fourier Transform wrt audio, then demonstrates a physical filter that screens the resulting convolution pattern to identify matches. Very cool: [this video]
Cites aaaaaaaaaaab · 2022-08 · on “AI-designed camera only records objects of interest while being blind to others”
Optical pattern recognition is an established field. Here's a simple version via Fresnel zone plates: [this video]
Cites Balgair · 2024-01 · on “Fluorite lenses: Corrective capabilities beyond ordinary optical glass”
Upping a cousin comment. [this video] Adding that, again, optics is a difficult and frustrating field. Don't worry that you're struggling to connect it. It took me a few years in an optics lab working hands on with light every day to really come around.