The 21st century's foundry

I've been busy with a lot of moving stuff, so that is why there has been a lack of posts. Hopefully I'll write more in the next few months.

I've been really enjoying (and nodding while reading) the Economist's special report on personal manufacturing as the next industrial revolution.

Flashing signs

The Economist has a neat article about how Casio is getting smartphones to talk to each other using flickers in their displays. Pulses of light are the way DMD and MicroVision projectors send out light, so you might be able to extend this idea to portable projectors.

Eye dust in the sky

The Economist has an article about civilian micro air vehicles and how society might react to them. Two interesting technical things I learned from the article was that (1) AeroVironment makes most of the US's micro air vehicles and (2) A company called SARA makes acoustic sensors for micro-air vehicles that block out wind noise and can detect other planes and do collision avoidance.

I want to talk about the article's focus on the societal impact of tiny visual sensors. The advent of such small camera-enabled robots will be the first of many technologies, with serious privacy concerns, that will probably come out in the next 10-20 years. For now, the available micro air vehicles are relatively large (laptop size or smaller). But smart dust and other futuristic visions are closer than you think. Sure, these ideas have been thrown around for the past two decades. But as we get close to the point when science fiction becomes commercial product, the human impact will be substantial and we must prepare for it. Millions of costless micro-cameras will envelope our lives in a 24 hour obtrusive sensor blanket. Combined with face detection, these micro-sensors will be able to identify individuals over a large area quite quickly; frankly, this would mean that end of privacy as we know it. Of course there will be air filters and particle blockers (for some predictions, see the Diamond Age), but the relentlessness of manufacturing processes and the possibility that these small devices will exhibit self-replication would probably overwhelm any stop-gap measure. I'm not sure I have any comments on how to make this situation better, because I'm pretty sure its inevitable.

Last 2011 posts: RIM and Solar optics

Its been a while since I've posted, but here are a couple of interesting things that caught my eye recently.

First, RIM: There are reports of a takeover for Research in Motion (RIM), the makers of BlackBerry. RIM has gotten hammered by the iPhone in the upmarket scene and by the Android tsunami in the mid and low cost sections of the market. In fact, the key (no pun intended) advantage of BlackBerry phones remain security (each device gets its own 32 bit pin) and an email server network that takes it own initiative, pushing email onto your device from, say, your employer's servers. These security characteristics are loved by those in finance and government, all over the world, and so RIM seems to have a niche market for now. Especially since these customer groups are quite loyal: look at how the finance world swears by the Bloomberg terminals. But further growth in RIM might be limited to just these markets and I think that's what shareholders might be unhappy about. Further drama in any possible takeover is due to the Canadian govt; according to this Nytimes article, which claims that Canada may not be open to a foreign takeover of what they consider an "important" company. Well I think, with state support, RIM could survive this lean period to fight another day. From my biased perspective as a supporter of camera-centric thinking, I think RIM should take advantage of its rep as a maker of tough, "phones for the Pro" and perhaps think about camera sensors that would be advantageous to law enforcement, firefighters and first responders: perhaps mobile IR and thermographic sensors on Blackberry phones?

Second, optics for Solar cells: We know that solar cells covert electromagnetic waves from the sun to electricity. But an important part of solar cells are the optics that make sure the maximum possible sunlight is captured by the cell. There are some cool companies out there that use ray tracing (geometric optics) to increase the length of the ray through the photo-sensitive part of the solar cell. The key here is to make the optics flexible and thin, so it can be "rolled out" (basically printed or fabricated) along with the solar cell. So the ideas that dominate solar optics are ones that exploit total internal reflection or rough surfaces. Designs from SolOptics and Morgan Solar follow this trend, and these links have cool explanatory diagrams.

You can also go beyond the optics that collect light, and think about modulating the incoming solar radiation into something that can be easily converted to electricity. The Economist has an article about a "lens" for a solar cell that is made of tiny pits in a sheet of tungsten. The pit size is such that heat from the sun is easily absorbed. But when this heat is re-radiated out from the tungsten sheet, it gets "lost" in the pits and reabsorbed into the sheet. Its a heat trap, that allows easy entry but difficult escape. So the tungsten sheet "trap" gets very hot, and a custom solar cell behind it is tuned so that the heat that does escape the "trap", is mostly converted to electricity.

Happy New Year!

Micro mirrors for 3D and color displays

I've been looking at some of Wallen Mphepö's work, after reading an article in the Economist. According to the article, Mphepö is a researcher at Taiwan's National Chiao Tung University. The research utilizes very tiny mirrors, and there are two applications for autostereoscopic 3D and passive color displays. By tiny, we are talking sub-pixel: many micro mirrors are packed into the space occupied by a single pixel extent.

In the first work on autostereoscopy, a projector is used. Now, usually, a projector projects an image onto a white, almost-lambertian screen. In this traditional scenario, the light from the projector would be uniformly reflected everywhere. But now imagine a "screen" made of tiny reflective micro prisms. Since the "screen" is a bank of tiny prisms, the light gets reflected non-uniformly, into specific directions. In particular, when a light ray from the projector, which corresponds to a single pixel, hits the "screen", it is reflected by a set of micro prisms that correspond to that pixel. If the projected image corresponds to concatenated left and right stereo images, you can specify the slope of the prisms so that the viewing space is filled up with places for an audience to see 3D without glasses. A nice diagram and explanation can be found here.

The second project follows a trend to create passive, reflection-based displays. This is in tune with the E-ink work and also the Mirasol displays from Qualcomm, both of which are easier to view in ambient light. Like the Mirasol displays, the micro mirror work is based on the same thin-film interference effects found in biology. Each micro mirror has two layers, each of which reflect some amount of the incoming light. The reflected light therefore has two components: light reflected from the first layer straightaway and light that is first refracted through the first layer and then reflected from the second layer. These two components are out of phase and interfere, giving rise to colors. The mirrors are controlled by MEMS devices, much like DMD chips, and so can change the incident viewing angle, which changes the perceived color. A nice overview is in the article.

An open-source hardware summit

One of my collaborators has an open-source embedded vision framework called "Embedded eye". He recently attended an open hardware conference. Not knowing much about open hardware, I looked through the conference and some wikipedia pages. I found some interesting projects, such as self-replicator that is basically a printer that can print itself and some work in the mobile space, to give users of smartphones the ability to customize and configure their personal tech gadgets. If you've ever clicked at the link at the top of this blog, you'll notice that personal manufacturing is an integral part of what I call micro computer vision. This is because hacking vision at small scales cannot just be limited to software: you need to be able to fabricate optical and electronic designs. The closer the fabrication experience gets to the convenience of printing paper, the more exciting the field becomes. But you can't fabricate something if its propriety: that is why open hardware is important. More power to them.

More tiny commerical cameras

Nytimes has an article reviewing new competitors to the micro four-thirds cameras. The most interesting is the Pentax-Q, which David Pogue claims is basically as good as an SLR, but extremely tiny. We are talking approx 4x2x1 inches, which is tiny for a supposed SLR killer. Lots of pictures in the article, including those taken by the cameras.