This describes how I built the Scintillation Bar, a work of perceptual art. (The wooden enclosure is described in more detail in this Instructable.).
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Step 1: Conceptualization
I started with a number of microlens arrays I have been collecting. These are linear arrays of tiny lenses built into the sensors of scanners and fax machines. If I see an abandoned scanner I will harvest the parts from it, including these. They are wonderful examples of inexpensive yet precision optics and have some interesting properties.
Step 2: Illumination
To highlight the optics of the microlenses, it's effective to illuminate them from behind. I experimented with several kinds of illumination including miniature incandescent light bulbs and LEDs of various colors. I finally settled on white LEDs. A particularly interesting effect happened when the illumination was changing. Because the microlens array directs different illumination to each eye, changing brightness can give the perceptual effect of motion. Though I could have used any number of controllable LEDs, I found that flicker LEDs that mimic the irregular brightness of a candle flame gave some interesting perceptual effects without an external controller or programming.
Step 3: Designing and Building the Circuit Board
This was a very simple circuit to make: an array of flicker LEDs in parallel. I used flicker LEDs from Evil Mad Scientist Laboratories. I experimented with a variety of colors, and finally used a mix of alternating warm white and cool white LEDs behind the microlens arrays. Bcause the flicker LEDs have built-in driver chips, they don't need current-limiting resistors and can be connected directly to the drive voltage (here, 4 AA batteries in series for about 6 volts). I made a 4" x 5" circuit board on the Othermill, in two parts which I then bandsawed in half and soldered together lengthwise into a 2" x 10" board. I wanted to be able to individually control the brightness of the warm and cool white LEDs so I put them on two parallel circuits.Each circuit has a 5K potentiometer in series as a dimmer.
Step 4: Installing the Microlens Into the Front Panel
I carefully measured the microlens array and laser cut a matching slot in a piece of 1/8" black acrylic. It took a little trial and error to account for the laser kerf but I got a satisfyingly tight fit. I set the microlens array flush to the front surface, and used black hot melt glue to fix it from the back. The black glue stick is not only lightproof, it is about as craft goth as it is possible to get!
Once the front panel was finished, it easily slid into the slots of the wooden case, and then the bottom screwed in to capture it.
Step 5: Wiring the Back Panel
I laser-cut the back panel out of 1/8 inch birch plywood, then sanded off the edge burns. I also cut holes for the rocker switch and dimmer pots as well as the 4 6-32 screws that attach it to the wooden box, and two additional holes for the hanging wire. I then finished it with with 600 grit sandpaper for a smooth finish. To verify the LEDs were the proper height, I temporarily affixed the circuit board with tape and closed up the box to check what it looked like from the front.
Step 6: Wiring the Back Panel
Once I matched the height of the front lens array slot with the LED circuit board, I attached the circuit board to the back panel with 3M foam tape. The battery holder is screwed into the bottom of the enclosure; I wired that in with a removable plug so the back panel could be separated if necessary. I completed the circuit by wiring each LED circuit to its dimmer pot and then both in parallel to the battery.
Step 7: The Final Result
The visual effect of the work is difficult to capture; but there is a definite perception of random left-right motion, even though nothing at all is moving. This is your visual system trying to make sense of a random inputs, and seeing relations where none actually exist. If this work can let you notice -- even a tiny bit -- the falsehoods which your perception occasionally presents, it will have fulfilled its purpose.