Friday, October 21, 2011

Liquid lens video

Repost for new video on liquid lenses:

This is a project that I built a few years ago when I learned about liquid lenses. They are quite useful for optical paths with small diameters.


  1. This might be a better idea if you are going to make a lens that big. Based on the work of Joshua Silver:


  2. Ben, nice work as usual.

    For future use:

  3. What project do you have in mind for the lens? It's a very cool device! I'm sure some I2C sample code exists for a 8 pin PIC if you need to shrink down the whole design.

  4. Hash, this may be used for a client's project. I've recently left academia, and am working with a for-profit company, so everything is "top secret."

    I probably could have bit banged the I2C protocol, since it's only going one direction and just sending a single value. I already had the arduino code written, so I just grabbed one off the shelf and used it.

  5. I bet it's something with a laser :)

    But what I was thinking was, I dont think larger lenses will work- The Meniscus' shape is only nice and lens-like at smaller sizes (or so I would think) and as size increases, the shape of the edges has less and less effect of the shape of the actual lensing area (the middle). And don't forget gravity- Go ahead and find two liquids with the same density as well as all those other things, and while you've done that, grab a copy of the GUT and a vial of Higgs bosons!

    Perhaps a better variable lens with liquid would be two flexible, clear pieces (even thin glass can work OK) with a sealed fluid in between- Varying the pressure on the fluid in the middle (actuator, piston, what have you) deflects the plates, to form a lens- Small amount convex, small amount concave. Pyrex and some oil combinations work quite well.


  6. Maybe a small laser :-)

    Did you take any measurements on the adjust-ability of the focal length? Just thinking about strapping a few of these to my head...

  7. Pretty cool, thanks for the info!

    I wonder how much laser power this lens can handle, or if it would have any problems with infrared.

    Have also wondered if you could make a variable focus mirror using electrostatic force on aluminized mylar; similar to how electrostatic speakers work.

  8. Hey, this video was pointed out on Cloud Nights ( and you will definitely have a large interest from the amateur astronomy group the more you progress, especially if you can create something in the range of a 6" objective (could be used as a very successful adaptive optics system).

    Just have a few questions:
    1) What price price range would you expect an eye-piece sized lens (20mm) to cost if one were to assemble everything themselves?
    2) How fast can you adjust the focus?

  9. Ben,
    Is the driver from the original camera not usable at all? Do you think it would be possible to keep the rest of the USB interface working and controlling the lens without the camera?


  10. Well you were certainly right about varioptic being difficult to work with. Just got an email back to them asking for information about my company before they'd even give a price range for their lenses. I'm guessing that if you can get them in those webcams then they probably cost very little.
    Anyone got any idea where they could be brought simply?

  11. This is very cool Ben!
    Hope to see more in the future

  12. I hate when companies make you jump through hoops to get product. It's not classified stuff, you can literally buy a webcam and get one!!

    Do what everyone does, make up a company name... Say you will be in the 100k+ units per year and need 10 samples ;)

  13. Ben, you are amazing!!

  14. There's an oil which is made for the precise purpose of having an oil the same density as water: brominated vegetable oil. I encountered it as part of the ingredients in certain colors of Gatorade, and was curious: what the hell is this doing in this product? Did they use it because merely hydrogenating vegetable oil wasn't evil enough for them? It turns out that the bromination is carefully done to achieve density exactly equal to water. In any case, in its diluted form, you can not only buy it but also drink it. Whether its long-term stability would be enough for a liquid lens is another question. Vegetable oils tend to gum up.

    But generally, the problem of finding a suitable oil probably is mainly the problem of finding an oil denser than water: once that is done, you can mix it with one of the many oils that are lighter than water.

    As for a really big liquid lens, well, as long as you never plan to subject it to any fast rotations. Those would cause the oil and water to switch places; the only force keeping them in the correct orientation is surface tension, which becomes a relatively weak force when the object size is scaled up. Having the oil and water be the same density wouldn't help with this; inertia tends to keep them in the same place relative to where they are, rather than the same place relative to where the lens is pointing. Once you have globs of oil floating around in the water, or vice versa, and perhaps sticking to the wrong surfaces, they might never get back to the correct places.

  15. Norman, thanks for the detailed info.

  16. I was looking for an easily variable lens, as last night's drinking adventure came forth with the idea of an enormous autonomous robot with a huge lens that would go around frying people like ants, and the initial idea was that trying to achieve something with a ferrous liquid might be the way to go, but getting that in a transparent medium might be hard work. Finding your video about liquid lenses was intriguing, although the comments here allude to size being an issue, so the mega killer robot idea is still not so feasible. However, contact lenses, or optical glasses with a similar idea might be a possibility? for super-hero-(military)-vision?