Colored shadows

one of the things i’ve been looking forward to playing with on the laser cutter are those moroccan lamps with intricate geometries:

i recently purchased a new grow bulb for my unfortunately ill poinsettia, and was intrigued by the colors it generated. unlike a typical shadow, which is usually binary (barring the cast generated by whatever surface the shadow falls on), this one was filled with different shades and colors since there are three or four different colors of LED in the bulb.

it makes me think you could combine multiple LEDs with one of those lamps and generate some pretty complex results from the interplay of the various colors.


You would have to find the right materials that can withstand the heat, but metal halide bulbs give an amazing shimmer effect. They could intensify the effect given in a lamp like this. I used to use metal halide bulbs in all of my fish tanks, which would then give the amplified shimmer effect when combined with the waves and turbulence in the water. …makes my brain start thinking about combining components that I shouldn’t… just to get a desired ambiance


it’s a good thought though i don’t think i want to generate so much heat. i’ll probably put the light in our loft, which gets pretty warm in the summer.

i like the idea of lighting the aquarium like that; we recently redid ours with bright white led strips.

we have an mh bulb downstairs but it’s a 1kW so probably a bit too strong for this application :wink:


With the creativity that comes with a Raspberry Pi and some LEDs, I am sure you could recreate the shimmer effect (and in multiple color schemes) that would be significantly lower ambient temps. This is an area that I need to get better at. The programming piece. You would think a guy that has a professional career in software QA would be better at something as simple as LED programming :confused:


Thinking of the ripple effect on the bottom of a pool, I want a light fixture that casts that for my marine/dive themed bar downstairs where I have a map of the Caribbean instead of the traditional mirror behind the bar.
Thought of a double-pane window type of container for the water with a mounting system that would allow a slight rocking to generate the surface turbulence with a halide bulb above it.
Would be a heavy elaborate light fixture, but I would love that effect.
Wish there were a way to accurately produce that with only LED’s, lenses and a controller. Difficult I would think because it is the intensity of the single light source focused by the lensing effect of the surface waves that gives that unbroken pattern that meanders around.

@jrnelson I think that idea of the colored shadows through the intricate pattern is a great idea!


You can experiment this effect with a smaller container like a flat bottom glass vase or maybe even an acrylic pan of some sort. A glass cup set on the desk with a high intensity LED underneath casts a neat pattern on the ceiling. :slight_smile: I think instead of rocking the fixture, you can use a vibrating motor and either waterproof it and submerge directly into the water, or attach it to a linkage with a small submerged diaphragm at the end.

Oooh, a small RGB NeoPixel ring underneath the water could lead to some interesting effects. If you’re doing a larger scale project, adafruit also has the NeoPixel Matrix grids so it’s like a solid field of point source light.

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I broke the glass on a Hue bulb and it casts similar shadows. I would not recommend that route though. The lamps are rather expensive to be smashing. :wink:


If you use one of those glass bottle cutters to cut the lamp glass with intention, technically you would not be smashing it. :slight_smile:

i thought about something similar. i think the best way to do it might be to sort of recreate a lava lamp - two immiscible liquids that when exposed to the heat of the lamp will create their own patterns through convection. the light would then change over time.


I don’t think it would be all that difficult. You could quite literally have a couple hundred LEDs in there, if it is a bigger fixture. Then have a few of them on different random pulse patterns at different speeds to replicate/simulate the effect. You could even have some fun building out a faux bulb to house them in.