This Art Project’s Video is Not a Time-Lapse

Artist Pe Lang uses linear polarization filters to create an unusual effect in his piece polarization | nº 1. The piece consists of a large number of discs made from polarizing film that partially overlap each other at the edges. Motors turn these discs slowly, and in the process the overlapping portions go from clear to opaque black and back again.

The disc rotation speed may be low but the individual transitions occur quite abruptly. Seeing a large number of the individual discs transitioning in a chaotic pattern — but at a steady rate — is a strange visual effect. About 30 seconds into the video there is a close up, and you can see for yourself that the motors and discs are all moving at a constant rate. Even so, it’s hard to shake the feeling of that one is watching a time-lapse. See for yourself in the video, embedded below.

Polarizing 3D Scanner Gives Amazing Results

What if you could take a cheap 3D sensor like a Kinect and increase its effectiveness by three orders of magnitude? The Kinect is great, of course, but it does have a limited resolution. To augment this, MIT researchers are using polarized measurements to deduce 3D forms.

The Fresnel equations describe how the shape of an object changes reflected light polarization, and the researchers use the received polarization to infer the shape. The polarizing sensor is nothing more than a DSLR camera and a polarizing filter, and scanning resolution is down to 300 microns.

The problem with the Fresnel equations is that there is an ambiguity so that a single measurement of polarization doesn’t uniquely identify the shape, and the novel work here is to use information from depth sensors like Kinect to select from the alternatives.

Homemade Polariscope is Super Easy to Make

[Abhimanyu Kumar] was watching YouTube videos one day when he came across something called a Polariscope — After learning how it worked, he discovered you can make your own using household items!

First off, what is a Polariscope? Well, put simply, it is a device that can show you the photoelasticity of a clear specimen, which can reveal the stress distribution in the material! And it is actually really easy to make one.

All you need to build your own is:

• A polarized light source (any modern LCD monitor)
• A transparent specimen (plastic cutlery, glass statues, plastic you can bend, etc)
• A circular polarizing filter (the cheap 3D glasses you didn’t return at the theater)

Then just place the objects in the order shown in the diagram and start snapping some photos. This would be really cool for checking stress concentrations in a project — provided you are using some Lexan or acrylic!

Which way do non-polarized film capacitors go? There is an answer.

If you, like us, thought that capacitor orientation only matters for polarized varieties like electrolytic capacitors you should read through this article. [Bruce Trump] looks at why some film capacitors have a stripe printed on one end and why their orientation can matter.

He has an image rolled into his post showing both axial and dipped capacitors with a black stripe printed on one end of the package. This is an indicator of what is going on inside of the component. The end with the line has a conductive foil layer which acts as a shield. But it seems that this shield will do its job better if you do a better job of designing for the capacitor.

The diagram above shows two op-amp circuits, both using a non-polarized capacitor that will affect the circuit if it receives external interference. [Bruce] discusses various aspects of this phenomenon, mentioning that although these careful layouts can be tested in your designs to prove which has more benefits, simulated applications (using SPICE) will perform exactly the same.