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Fourier Optics used for Optical Pattern Recognition

Huygens Optics

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  • Recommended by 5 people: 5 on Hacker News.
  • A classic. People kept recommending it from 2021 to 2025.
  • May be out of date. Uploaded 6 years ago, in an area where tools change fast.

Intermediate. Assumes working knowledge.

102K views6 years ago5 recommendations

Computer scienceAI and machine learningComputer visionAlgorithms

Huygens Optics explains the Fourier transform and demonstrates how to perform analog pattern recognition using lenses and optical filters.

Optical Fourier transformations were performed using small lithographic patterns of different characters. A DLP projector can be used as a Fourier filter to do simple pattern recognition. Video contents: General introduction Fourier explained (simple) Digging a bit deeper (sorry, could not resist) Fourier on images Fourier transforms using optics Setup and results Fourier filtering The 2D Fourier transformation images were calculated using freeware developed by Kobe University. You dan download this tool from: cas.eedept.kobe-u.ac.jp/WelcomeES1/OpenSoft/FFT2D/index_en.h… Conversions of 2D images to 3D were done using Gwyddion. This very advanced piece of software is can be downloaded for free from: gwyddion.net/download.php To illustrate 2D Fourier transform on an actual image, a small part of an M.C. Escher drawing was used. While editing the material for this video I found out that the Applied Science channel made a somewhat similar video on "Optical Fourier" already in 2012: youtube.com/watch?v=wcRB3TWIAXE . Luckily the angle is somewhat different. This video gives a different (and deeper) perspective on the math behind Fourier transformations; youtube.com/watch?v=7mkn47hqqkc If you want to go all the way, read the wiki page on Fourier. If you dare. en.wikipedia.org/wiki/Fourier_transform

Why it's here

5 people recommend this

What people say. Highly recommended for its exceptionally clear physical and visual explanation of the Fourier transform and optical computing.

jstriebon Hacker News • Recommends

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 link to this video
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orlpon Hacker News • Recommends

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: link to this video
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jstriebon Hacker News • Recommends

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: link to this video
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ulnarkresstyon Hacker News • Recommends

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 lens0. It is used for "analog" pattern matching1. There is an interesting video explaining this on the Huygen Optics Youtube channel2. 0 - link 1 - link 2 - link to this video
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CamperBob2on Hacker News • Recommends

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: link to 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...
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infogulchon Hacker News • Recommends

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: link to this video
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aaaaaaaaaaabon Hacker News • Mentions

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: link to this video
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Balgairon Hacker News • Mentions

On “Fluorite lenses: Corrective capabilities beyond ordinary optical glass”

Upping a cousin comment. link to 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.
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TeMPOraLon Hacker News • Mentions

On “Pre-Trained Large Language Models Use Fourier Features for Addition (2024)”

IDK, the more I learn the more it seems to me that Fourier transform is reality's cheat code. It keeps showing up everywhere. Like, the other day I learned0 that if you shine a light through a small opening, the diffraction pattern you get on the other side is basically the Fourier transform of the aperture outline. (Yes, this also implies that if you take a Fourier transform of an image and make a diffraction grating off the resulting pattern, projecting light through it should paint you the original image.) -- 0 - link to this video
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