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I previously worked on Virtual Reality and other hardware at Valve.  I currently work at Google[x].

Prior to starting at Valve, I built computer peripherals such as keyboards, mice, and joysticks that were designed to be used inside MRI machines.  My company, Mag Design and Engineering, sold these devices directly to researchers at academic institutions who used them to publish scientific papers in peer-reviewed journals.

After work, I spend time on many different types of projects that usually involve circuit design, machining, material selection, and general fabrication/hacking.  My favorite place to be is my home workshop.

ben dot krasnow at gmail




Monday, December 19, 2011

LED mounted in a contact lens for possible virtual / augmented reality displays

Every so often, internet news aggregator sites run a story about a research group that put an LED into a contact lens, then inserted it into a rabbit's eye. I figured that I would try the same thing, but put the lens into my own eye. I accomplished this by laminating a coil of wire and an 0402 surface-mount LED between two ordinary soft contact lenses. I was hoping the lenses would stick to each other, but they did not, so I ended up fixing the edges together by pinching the plastic together with hot tweezers. This held well enough to capture a minute of video with the LED illuminated in my eye. For video purposes, I mounted the LED facing outward. An actual VR/AR display would have the LED facing inward.

I powered the LED by using a very primitive spark-gap transmitter built from a mechanical relay to send RF energy into a larger coil held near my eye. The large coil coupled the energy into the contact lens coil and pulsed the LED.




  1. Sir you are amazing.

  2. That Is Awesome Great Job!!!!

  3. This is a good start. Now you need to build me a holographic projector built into my contact lens'. The led is a good place to start your research from, but now you need to switch to quantum lasers. I would also suggest figuring out how to etch the miniture optics into the space between the surfaces of the contact lens. Finally, I don't want to pay more than $0.50 -Oh and I perfer the daily wears over the reusable contacts.

  4. That's useless, it's to heavy to keep in the center of eye itself and you can't see anything by this lens and one question: WHY? What you can do with this? Nothing, special. And how do you want to improve it using house tools ? :) Nice idea but that's all what you can do with this in your house, sorry :)

  5. "That's useless"

    Welcome to science ;)
    Lovely idea:)

  6. May want to check out the Colpitts Oscillator and a man by the name of Marin Soljacic. Nothing like an evanescent waveguide.

  7. Haha, you're hilarious Ben! :)

    I've got a Tesla Coil that might power the thing. It lights up a 4 foot fluorescent tube from 4 feet away. I'm nearby if you wanna try it.

    Also, I just saw a "How its made" on contact lenses. Its the first episode, on Netflix. You might have more luck casting the coil into a cylinder and then machining a new lens out of it. Its not too terribly involved - certainly not too much for you!

  8. Very impressive, but I doubt I would ever try experiments like this on my own eyes - your eyesight is far to valuable to risk, I would say. Im still looking forward to future AR systems for (ordinary) human use :)

  9. mad russian dude Krasnow )) Mission impossible 2012 ))

  10. could you give me the part number for the led?

  11. Anonymous, the LED is Digi-Key part# 511-1653-1-ND with an mfr# SML-P11UTT86

  12. I wonder if a laser from a blueray could be used to fuse the two contacts lenses together by only melting the material close to their interface surfaces? It might be possible to fuse the two surfaces without making the outer surface so rough...

  13. You could use a 0402 size capacitor to form a tuned circuit. Use RFID to power it.

    Measure the inductance of the coil and pick a capacitor value to tune to approximately 13.56Mhz (the frequency of most common RFID systems).

    The LED should illuminate whenever you are near to a source of RFID - eg. a subway, and NFC equipped cell-phone - a Skylanders Portal of Power.

    Keep up the good work!

  14. I *think* that contact lenses are made of a semi acrylic type plastic. You may be able to make a jig to clamp the two lenses together with just the edges exposed. The with a cotton bud (Q-tip)wet the edge with some methyl chloride. This would cause the edge to dissolve slightly and fuse.

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