Howto Reverse engineer a digital web-camera to build a custom liquid lens platform

[JonathanCline]

Found on the blogosphere,
http://benkrasnow.blogspot.com/2009/07/experimenting-with-liquid-lens.html

My summary of the "How-to" (see the original post for pictures)

1. Buy this webcam camera. "I found an actual product that had the
Varioptic lens in it: Digitus DA-70817. [..] I got in touch with a
German distribution company called Assmann (no joke). I exchanged a
few emails with a friendly person there, and she sent me five of these
cameras (about 25 euro apiece with the usual outrageous international
shipping charge)."

2. Tear it apart to get the liquid lens.

3. Build a mechanical frame for the lens, which has conductors
embedded to make electrical contact. "I removed the lens from one of
the cameras and mounted it between two pieces of copper clad board."

4. Buy some samples of the liquid lens driver chip (creates the
special high voltage for changing the focal length). "The other
company that makes liquid lens drivers is Supertex. They will sell
samples of their HV892 at a reasonable price, but the chip is only
made in a 10-lead 4mm x 4mm DFN package with .65mm pitch."

5. Design & Fabricate a simple PCB which will hold the liquid lens
driver chip, with headers to connect to your favorite
microcontroller. "I ended up designing my own PCB for the chip and
having them made at http://www.expresspcb.com/."

6. Write some microcontroller code to send commands to the liquid
lens driver chip. "The Arduino sends a value between 1 and 255 to the
HV892 via the I2C bus. The value controls the HV892 output voltage,
and hence the lens's focal length."

Don't forget to host the microcontroller code (simple though it is) on
an open source site such as sourceforge.net or github.com.

7. Test the setup by shining a laser pointer through the lens, while
the Arduino changes the focal length. "I used a laser pointer to show
the different focal lengths that the lens can achieve. "

8. Done! Post your results.


Optional steps instead of 4-6: forget buying the proprietary chip,
and design a custom circuit which supplies a variable 30VAC-100VAC @
under 1mA with around 1kHz-10kHz frequency.


## Jonathan Cline
## jcl...@ieee.org
## Mobile: +1-805-617-0223
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