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.
Continue reading “Polarizing 3D Scanner Gives Amazing Results”
[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!
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.
Early LCD monitors had some pretty awful issues when not viewed from directly in front of the screen. These days the technology has really minimized this flaw, but if you still have a cheap monitor on hand you might want to pull it out and give this hack a try. [Chris Harrison] is using oblique viewing angles to display additional information on cheap montiors.
Take a look at the two images above. The one on the left is taken from directly in front of the monitor and looks normal. But if you view the same screen from the side, the financial information is obscured. This is by design. Using very light colors, the obscuring characters are almost indiscernible from straight on, but you can just see them there a little bit (they look like burn-in does on a CRT screen). But from the side, these light colors become quite bold and blend with the rest of the data on the screen.
This works because of the polarizing filters on an LCD screen. You might want to watch [Bill Hammack] explain how an LCD works if you’re not familiar. Because the viewing angle color changes are a flaw and not a feature, manufacturers make the up-and-down angles the worst to improve on side-to-side viewing. [Chris’] experiments play into that by using a computer monitor on its side. Check out the video after the break to see some of the different applications that he uses this for.
Continue reading “Using an LCD’s poor viewing angle to your advantage”
[madaeon] couldn’t find a digital viewer for his stereoscopic 3D images. He felt that he could probably build one, so he did. He found two identical digital picture frames and made a custom rig to hold the two frames. The method he is using involves polarized lenses, so you do have to put glasses on to see it. Being polarized though, you get full color, like modern 3D movies. We think it would be even nicer to see them without glasses, but some people have a really hard time with this style of 3d image.