He disassembled the laser printer and painted the eggs with tangible patterns

Hostem Rozst

The egg has been painted in the Czech Republic for centuries. But let’s bet you haven’t seen this way decorated. Stail laser module from discarded printer, unconventional case, ingenuity and a lot of patience.

How to paint an egg differently, not anyone before dark? U tet rok v ad Ing. Ji Zemnek, a doctoral student from the Department of Children’s Technology, FEE BUT, showed that they are decorated with Easter eggs, which have not yet occurred to anyone. Last year, he used the stroboscopic effect and danced drawings on Easter eggs in an illusion reminiscent of film (more in our previous line).

This year, it took on the stroboscopic effect, but completely changed the way it was painted on eggs. While in the last two views he used the cartoon robot Eggbot, this time the color on the eggs is principled.

Transient laser drawing

There was a bite on the meeting, and then he dropped it, Ji Zemnek remembers, who gave us permission to handcuff his new video (original on YouTube). The laser module from the color laser of the printer had been lying in his room for some time. When he got the photochromatic colors (see box), he thought of combining these elements together.

With his student Filip Richter, they learned different ways to use a laser module, which can only create a one-dimensional colored river, to decorate Easter eggs.

It was a series of different long problems that we had to solve, to Zemnek. For example, to find out how to connect the unit from the printer, even if we did not have the original schematic. It was necessary to figure out how to quickly switch on the laser diode, because the cheap modules that you usually buy are not good for it.


The whole device includes a laser module and a rotating egg stand

Pure non-electronic problems also awaited electrical engineers, such as first spreading the photochromic pigment, which was applied to the eggs with a spray gun so that it was evenly distributed on the egg.

So much work…

We got to the point where it started to work quite quickly. But then it took a long time to tweak everything to make it work reliably, I think Zemnek, who has quite a lot of experience with the creation of similar popular science hi-tech toys. Two years ago, together with our tenants, he enlightened you from a tram grinder, and in 2010 he taught the needles of carols again.

It was not necessary to grind from the arrest. At least for the preparation of the pattern drawn on the egg, the enthusiasts could get the algorithms out of losk. The movement you see on the eggs is the result of the rendering of new information (new illuminated pixels), and most of the time it is the use of a stroboscopic effect.


Drawing moving pictures on eggs using laser and photochromatic pigment

We had the biggest problem with the laser diode, because it had to be quite powerful, if the laser were in place, the steady power would be as in a normal pointer, explained Zemnek. Because the laser is melted, the power must be increased so that the power delivered to the surface is sufficient.

Secrets of stroboscopic animations

Because the egg rotates quickly (speed once and tikrt per second, as needed by the artwork), the camera does not capture this movement smoothly, but captures only 25 frames per second. This can be forced so that the egg figures, which are drawn in a precisely spaced range, merge into a smooth animation for the viewer.

Stroboscopic principle

The principle of the strobe effect: the rotating ball illuminated by the strobe is always visible only during the flash. It looks like it’s actually flashing in the city.

The laser rendering then added a new dimension to the whole effect, because now Zemnek could not only create animations with the help of a stroboscopic effect, but even edit these animations on the fly, because he could either draw (highlight) or redraw (change) the pale pattern with the help of a laser module.

The unit has a hexagonal mirror, which rotates at a constant speed of 160 times per second, which means that the laser scans at a frequency of about 1 kHz, ie a thousand times per second, describes Zemnek. When the scan is divided into approximately 700 pixels, the microprocessor must send the laser signal 700 times faster.

Principle described

Kotou z pstroje Phenakistoscope, pedchdce kinematografu

When watching a video, it is not easy to know that it is not a trick or a movie. But it is also good that the stroboscopic effect in this form works only thanks to the stone. On your own, you would not see these animations unless someone illuminates the egg with a fast flashing light at the same frequency as the camera.

For a while, it seemed that the video could not be produced by Easter: The first module we had for it was destroyed during experiments. U nezbval as to order a new one, Zemnek describes the origin of the video. We removed a diode from a star blu-ray drive here. It worked really well, but unfortunately it started to give its promise exactly when we started recording the video. All we could think of was buying a new blu-ray drive, disassembling it and picking up a laser diode. The budget for special effects has thus increased significantly. It’s up to the girls to judge whether the blu-ray drive has paid off.

Krsn Easter!

Take a look at the first Eggstatic video from 2016:

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