Create an Aurora Of Your Own

Throughout our day-to-day experiences, we come across or make use of many scientific principles which we might not be aware of, even if we immediately recognize them when they’re described. One such curiosity is that of caustics, which refers not only to corrosive substances, but can also refer to a behavior of light that can be observed when it passes through transparent objects. Holding up a glass to a light source will produce the effect, for example, and while this is certainly interesting, there are also ways of manipulating these patterns using lasers, which makes an aurora-like effect.

The first part of this project is finding a light source. LEDs proved to be too broad for good resolution, so [Neuromodulator] pulled the lasers out of some DVD drives for point sources. From there, the surface of the water he was using to generate the caustic patterns needed to be agitated, as the patterns don’t form when passing through a smooth surface. For this he used a small speaker and driver circuit which allows precise control of the ripples on the water.

The final part of the project was fixing the lasers to a special lens scavenged from a projector, and hooking everything up to the driver circuit for the lasers. From there, the caustic patterns can be produced and controlled, although [Neuromodulator] notes that the effects that this device has on film are quite different from the way the human eye and brain perceive them in real life. If you’re fascinated by the effect, even through the lens of the camera, there are other light-based art installations that might catch your eye as well.

14 thoughts on “Create an Aurora Of Your Own

    1. It ideally requires a collimated or a point light source, the lasers without collimators are of the second type. I tried an XM-L2 LED, and it generated a similar effect, but when hold close to the water surface, the effect was very blurry, when hold away, most light would not hit the water surface. There is nothing special about the laser, its just that it’s a point light source, but sunlight for instance can generate a similar effect as well.

        1. Well in the linked page I explained that depending on the oscillatory frequency, amplitude and other factors, the standing wave pattern could converge to something static as shown in the original posted video or dynamic (as shown in the comments). The top video is not a still image, you can see some circles moving around, which are dust particles floating in the water, but I completely agree with you that its not the most appealing video.

    1. Thanks for the link, the originally posted video shows a converging pattern, which I find much less appealing. I did this project in a rush, so I just showed the main features of it. For instance in all videos, frequency and amplitude were kept constant, although they can arbitrarily modified on the fly as the ESP32 has enough power to perform all the floating point calculations in each loop iteration. The lasers are controlled through PWM, so their intensity can be controlled as well. Here is an example of the modulation of the laser intensity in an oscillatory manner:

  1. Nothing like an aurora I’m afraid, seeing the headline I thought this would be about some sort of vacumm chamber with high voltages and low pressure gas,to make glowing plasma. This laser caustics project is very cool, but the headline really isn’t correct here.

  2. I remember something like this effect being used for some kind of projector.. It would’ve been in the 90s. Popsci or popmech. Supposedly, by they could get a laser to scan (like a tube TV) By sending sound waves into a water chamber through witch a laser passed. Although it’s hard to imagine it’d be quiet or fast enough to be useful.

  3. Seems to be there was a recent post that was similar using irregularly shaped transparent objects to similar effect.
    Understanding refractive index and photonic interaction at the boundary layer coupled with a little creativity could go a long way to add a little more randomness to the project. Try using a petri dish instead, mounted to a gear reduction motor(cheap clock motor from the local craft store will do, just make sure it has a sweep second hand), fill it partly with glycerin, add some glass marbles, plastic marbles, jelly marbles(hydrogel), and have the laser shining up through one side. Make a stationary arm with a small flat end extending into tho mix to rearrange the objects as the motor slowly turns it. The beam will react differently as it passes through the differing objects due to their differing refractive indexes. There will be several boundary layers through which the beam will have to pass. You may want to use a deeper container to nearly cover the objects with glycerin, depending on the size of the objects. Now add some irregularly shaped transparent objects. Some scraps of clear plastic will do if the broke edges are not too opaque.
    You can get some differing effects by using different liquids as well. Another interesting effect is to use immiscible liquids, such as water and oil (clear oil, like mineral, not vegetable), but you will need to provide a little more agitation with a moving arm or it will prove rather boring. Don’t get too carried away and try a complete layer density stack, as you will likely end up diffusing the beam into oblivion.
    Oh, and please remember to protect your remaining eye with filtering media appropriate to the wavelength of the laser.

  4. Points laser at flexible plastic mirror. Adds a couple of servos to the back of the mirror to bend it a little bit.
    Pretty much the same effect.
    There is a oil based projector that uses high voltage to move the oil around.

    Personally I was hoping for a vacuum chamber and high voltage to create a mini auroa.

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