Retrotechtacular: Turn On the Magic of Colored Light

title cardChances are, you take color for granted. Whether or not you give it much thought, color is key to distinguishing your surroundings. It helps you identify fire, brown recluse spiders, and the right resistor for the job.

In the spotlight this week is a 1950s educational film called “This is Color“. It also happens to be a delightful time capsule of consumer packaging from the atomic age. This film was made by the Interchemical Corporation, an industrial research lab and manufacturer of printing inks. As the narrator explains, consistent replication of pigments is an essential part of mass production. In order to conjure a particular pigment in the first place, one must first understand the nature of color and the physical properties of visible light.

electromagnetic spectrumEach color that makes up the spectrum of visible rays has a particular wavelength. The five principal colors—red, yellow, green, blue, and violet—make possible thousands of shades and hues, but are only a small slice of the electromagnetic spectrum.

When light encounters a transparent material more dense than air, such as water or glass, it has to change direction and is bent by the surface. This is known as refraction. A straw placed in a glass of water will appear bent below the surface because the air and the water have different refractive indices. That is, the air and water will bend or refract different percentages of the light that permeates them. [Read more...]

3D printing with visible light

This 3D printer manages some pretty fantastic resolution, and these are just the early results of [Junior Veloso's] build. He put together a machine that prints objects in resin that cures in visible light. To print, a thin layer of raw liquid resin self-levels across a printing surface and a DLP-based projector shines light from below, onto the portion to be hardened. The z-axis then pulls that layer up and the next to be printed will become the newest bottom layer. Horizontally the printer yields 1024×768 resolution with a layer thickness as small as 0.01 mm. No wonder he’s turning out this kind of quality.

The model above took 5 hours to print, with eight-second exposure for each layer, and 0.1mm layer thickness. There is lots of good information on his blog, from the early planning, to the finished hardware so take some time to learn about this fascinating project.

Update: Thanks to reader [Nave.notnilc] for pointing out that we’ve seen a chemical 3D printing technique before.

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