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Project #3 - Laser X/Y Oscilloscope |
The last project in my engineering life and before
returning to student academic life was to design a
special-application digital storage oscilloscope for
use in ion implanters. I have since often used a
scope for audio testing applications.
My third project, however, was quite different from the typical scope in that I used 4 loudspeakers to mechanically move a typical laser pointer suspended by 12-pound fishing line. Of course, the mass of the pointer, and the flexibility of the mono-filament fishing line and o-rings for securing the pointer, restricted the frequency response of the display. Besides, I decided it was time to build something that would be hacking just for fun. There is nothing serious about this project, although it is a true projection scope. I don't know of any commercial projection scopes, but with the right software, a stereo input on a computer, and a video projector, a far more accurate display would result, including the ability to view time-domain measurements. Ah, but this is a hacking class! I began my presentation with a display of several |
Lissajous patterns with X and Y sine waves applied to
the amplifier in the 60-85Hz range, varying only one
frequency at a time to obtain differing patterns.
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Fellow hackers watching the laser in action. Photo by Joseph Lopez. |
Following the sine waves, I played some folk music
selected for its bass content, the left channel driving
the X axis and the right channel driving the Y axis,
yielding a mass of random patterns set to the music
being heard from the speakers.
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