In this instructable you will learn how to create colored shadows on a big surface using colored LED-lights. The experiment requires very few materials, but the effect you get is amazing. Use it to create your own lighting exhibition, party booster, entertainment for your children, or just as a fun experiment.
How it works:
Colored light mixes according to additive color where black consists of light of no wavelengths (no light at all) and white consists of light of all visible wavelengths. The human eye contains of cones, responsible for our color vision. These cones exist in three different types each most sensitive to light of one type of wavelength: long (red), medium (green), short (blue). These three types of cones allow us to see all visible colors; e.g. gives light of yellow wavelength just the same stimulation to the cones in the eye as a certain mixture of light of red and green wavelength. Subtractive color, on the contrary, starts from white and by absorbing light of a certain wavelength another color is achieved; when all wave lengths are absorb black remains. This is what happens when pigment colors are mixed when painting.
In this experiment the light from the different light sources hits the wall from different angles. Due to this you can create shadows of seven different colors: blue, red, green, black, cyan, magenta, yellow and black. A blue, red or green shadow, or representations, of the object occurs on the wall where light from the two other light sources are blocked; Cyan, magenta or yellow occurs where only one light source are blocked, creating a mix of the two others; a black shadow occurs where all three light sources are blocked, e.g. if the object is placed close to the wall.
Step 1: Used in This Project
1. RGB-led lights in the colours red, blue and green.
2. Objects of various shape (wires, cups, sticks or yourselves)
3. Reflective white surface
4. Dark room
Step 2: Set Up the Colored LEDs
For the best effect put the light sources according to their wavelength, i.e. green in the middle! Place them slightly angled to each other, extend the distance between the light sources to for wider shadows.
White led or other white light emitters can be used instead of RGB-led if they are combined with optical filters that only let light of a certain wave length through. Coloured cellophane can be used instead of optical filters although the colours will be less exact.
Step 3: Set Up the Projection Surface
Put the light sources on a distance from the wall that gives you a good compromise of light intensity and enlightened area.
If possible use strong light sources that allow you to control the intensity in order to create a perfect white light. For light sources with low intensity use reflective frames to focus the light and/or place them on a shorter distances from the wall.
Step 4: Experiment!
Now the setup is finished for your very own light exhibit. Feel free to experiment with different objects of different shapes and from different distances of the light sources. The effects will be fun and inspiring!