My Bead Disc

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My Bead Disc

Postby Lawnboy » Wed Jan 15, 2014 10:37 pm

It’s been a long time since I’ve done any NBTV work, so to get back into it, I tried my luck at a simple bead disc attachment for my monitor. The disc is made out of 3/16” foamboard from a local office supply store and some 3/16” plastic beads from Ebay. I made a direct copy of the Peter Yanczer disc that the monitor normally uses by taping it to the foamboard circle and punching out the holes with a needle. I then took a pencil, put it in a drill press, and “drilled” out the holes to the proper size (its surprising how much paper and foam can wear down cheap wood.) The beads slipped in place and I gave it a shot. Here are the results.
The only thing I had on hand that could act as a point source was an RGB color array that I built previously. The single LED is similar to the club’s 3 watt white emitter but with 3 RGB dies (one per color) instead of the usual white one. The color mixing is quite good. I placed the LED 3 or 4 inches behind the disc without any kind of diffuser or light box. It seems enlarging the apparent size of the LED by either a small diffuser or a lens will reduce the line structure, although I haven’t tried this yet. I may also be able to simulate different aperture shapes this way as well.
The image is easily 3 or 4 times brighter, and the same size as the Nipkow image. In real life some of the colors are a bit more saturated and the image looks like the uppermost of the three scans. The cloudiness in the lower scans is from light reflecting off of the shelf that the LED sits on.
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Postby holtzman » Thu Jan 16, 2014 8:12 am

Congratulations, it looks promising! The problem is that drilling larger holes is always less accurate than drilling small ones, and of course a sharpened pencil is not the best tool... And foam seems to be too soft and irregular to hold the beads so steadily. Anyway it looks impressive and thank you for posting!
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