Audio: Laser microphone patented

Wired.com reports on a new type of microphone designed and patented by David Schwartz. The principle behind the design involves a laser beam measuring the vibrations of smoke particles in a tube as they are deflected by sound. There are two interesting video clips on the Wired.com page - one showing a demonstration of the second prototype and the other showing the components of the device.

Enjoy!

Education: Yenka Light and Sound modeling software

I've been using Falstad's freeware Java applets for teaching acoustics and oscillation concepts in the classroom for years now. I recently decided to give Crocodile Clips' Yenka Light and Sound modeling software a try after some of my own children enjoyed using it in school. At first it was to take advantage of the free license for home use (yes, FREE). Now, however, I'm going to use it in classes thanks to the numerous models already built-in and even more content online. My favorite built-in model so far is "Speed of Sound" - which lets you add other media, such as vacuum, water, and wood, and see how the speed of sound changes and then interacts with the sound wave in air, assuming it exits the extra media at all - very cool!

Not to leave optics out, there are informative models for angles of reflection, refraction, mirrors, lenses, telescopes, and more. For instance, to show that the angle of incidence equals the angle of reflection, the student drags two protractors into the workspace and measures both angles as the (virtual) beam of light bounces off the mirror. Simple, but effective. Many more sophisticated models are available too, plus you can build your own and save them for later use (as an educator, I like that).

Yenka also covers more than the physics of sound and light - mathematics, chemistry, computers, electronics, and other packages are also available. I've tried the chemistry package with my boys. Being boys, they were particularly pleased with being able to experiment with (virtual) dangerous substances after having to suffer through the kid-safe chemistry sets sold in stores these days.

Crocodile Clips is based in the UK, so American and other visitors to their website may not understand the references to terminology used in the British education system. Luckily, the laws of physics do not change as a result of the software leaving the UK! Yenka is a free download for students to use at home. Use outside of the home requires buying a license, of course. Finally, it works on Mac and Windows operating systems.

Enjoy!

Photography: Year's top ten tips and tutorials

Digital Photography School has an excellent roundup of ten tips and tutorials for this year.

Enjoy!

Optics: Adjustable glasses invented

Inventor Josh Silver (UK) has developed a pair of eyeglasses that are instantly adjustable by inflating or deflating a fluid-filled sac in the middle of the optical surfaces.

Read it all on Gizmodo.

Image Recognition: Military requirements push technology forward

The Strategy Page has an article about how the proliferation of video on the battlefield (e.g. from surveillance cameras and even night vision goggles) is driving technology development. Initially, it was the UK (United Kingdom) that drove image recognition technology with its massive deployment of CCTV in public spaces (e.g. train stations, airports, city centers, and shopping malls). Now, it is the military.

The benefit from computer-assistance in analyzing video comes from the following:

1. Volume (i.e. the sheer number of cameras and, hence, images to be monitored and/or analyzed)
2. Concentration (i.e. the human visual system loses the ability to concentrate effectively on images after about 20 minutes of continuous viewing)
3. Memory (i.e. computers can track and, possibly, predict more things simultaneously than a human can because, generally speaking, computers are not nearly as attention and working-memory limited in the short-term as humans and far outstrip us in their ability to recall video sequences over the long term - they can just play back the video recording off of their hard disks)
   

The article claims that the abilities of computer systems to recognize patterns is rapidly improving and approaching that of humans - that is no small feat as humans are simply amazing in their ability to perform real-time pattern analysis.

One intriguing point made in the article is that the current conflicts are generating a lot of real-world recordings of "bad behavior" that can be used to train and test new pattern analysis and prediction algorithms - training data like this is like gold to us signal processing types!

Enjoy!

Optics: "Look Mom, no lens!"

Similar to a child demonstrating how he can ride a bicycle without using his hands, now we have scientists taking pictures without a lens.

Upon reflection, it was a predictable next step. First we had the major advance of refocusing out-of-focus images by, in essence, building a correction lens, all in software. This is what allowed NASA (the USA space agency) to correct some of the Hubble Space Telescope images after it was put into orbit with an out-of-focus optical chain.

But it one can simulate a lens well enough to correct an image, even if imperfectly, why not replace the real lens with a simulated one and focus the unfocused image received by the (lens-less) sensor? That is what the team at Argonne National Laboratory (Illinois, USA) is working on. Of course, simulations are rarely, if ever, as good as the real thing in all aspects, but if for their particular problem (X-ray imaging) the simulated lens is better than their real one, then they will have improved the imaging system and advanced the state of the art yet again.

Optics: How camera lenses are made

YouTube has a fascinating video segment on how camera lenses are made.

(Hat tip: Gizmodo)

Optics: Liquid camera lens, no moving parts, now with zoom

New Scientist has an article on a different type of camera lens - it isn't made of glass or plastic, but instead uses the boundary of an oily liquid and water, which can be shaped by an electrical voltage to different amounts of curvature. Liquid lenses are used in some mass market products. The twist here is the ability to zoom. This latest research development still has some issues that need to be worked out if it is to supplant existing commercial technologies for the mass market (i.e. cheap, plastic lenses), but the principle seems to be sound. That bodes well for it finding at least a niche problem to solve.

Ultrathin folded telephoto lens

Engineers at the University of California San Diego have created a folded lens by machining reflective surfaces into a optical crystal. this technology has the potential to shrink lens assemblies, which would be beneficial to lots of devices, such as cameras and night vision gear. However, this is still early stage research and hurdles remain - such as its inherent narrow depth of field. That being said, there are ways around that problem that might work for selected applications where thickness is more important than length (where I imagine that additional lenses with different focal lengths could be positioned on a rotating disk or similar arrangement to be employed as needs changed) or post-processing power consumption.

The work has been published in Applied Optics (February 1st, 2007)

(Hat tip and image source: PhysOrg)