News/General

On the face of it this doesn't sound like much but the researchers hope to be able to use the results for optimize crystal growth.

Firing laser pulses into supercooled water creates ice crystals at specific locations in the liquid.

Using laser pulses to crystallise supercooled water into ice may seem counter-intuitive, but that's exactly what researchers in Germany and the UK have achieved. Because the pulses can be focused to a specific point in the liquid, the researchers believe that their technique will be valuable for future material and crystal growth studies. (Physical Review Letters 99 045701)

Laser pulses turn water into ice - optics.org

Researchers at MIT's George R. Harrison Spectroscopy Laboratory have developed a new use for laser interferometry that allows 3D images of the internal structure of cells to be created in just 0.1 seconds. Michael Feld and his team use the change in refractive index of a laser beam passing through the cell to create a series of 2D maps.

The researchers made their measurements using a technique known as interferometry, in which a light wave passing through a cell is compared with a reference wave that doesn't pass through it. A 2D image containing information about refractive index is thus obtained.

To create a 3D image, the researchers combined 100 two-dimensional images taken from different angles. The resulting images are essentially 3D maps of the refractive index of the cell's organelles. The entire process took about 10 seconds, but the researchers recently reduced this time to 0.1 seconds.

One major result of this research is we can now see the internal structure of cells without modifying the cells themselves through fixing or adding dyes.

"When you fix the cells, you can't look at their movements, and when you add external contrast agents you can never be sure that you haven't somehow interfered with normal cellular function," said Badizadegan.

The current resolution of the new technique is about 500 nanometers, or billionths of a meter, but the team is working on improving the resolution. "We are confident that we can attain 150 nanometers, and perhaps higher resolution is possible," Feld said. "We expect this new technique to serve as a complement to electron microscopy, which has a resolution of approximately 10 nanometers."

Thanks to ScottY for the link.

This is pretty cool and something that even hobbyist holographers could make.

Laser Focus World is reporting that researchers at New South Wales University have developed a holographic astigmatism test that's faster to use than the lens-flipping "how does the chart look now?" test we've all endured when having our eyes checked.

The current method of looking at a distant object through a number of lenses to prescribe corrective glasses is at best cumbersome. In an alternate approach, the researchers recorded the wavefront emanating from various sunburst patterns located at different distances from the eye in a hologram. When a subject views through this hologram (illuminated by a plane wave), he or she will see the images of various sunburst patterns located at different distances from the eye.

Unfortunately there's no additional information at the university site.  Perhaps they'll put something up soon.

Optics.org has a bit more information and a few extra photos available.

I don't have one of these babies yet but you can bet they'll be on my Christmas list.

Laser tag is sweet. R/C helicopters are sweet. When you combine the two only good things can happen. That's why I'm pretty amped about the news that a Chinese toy maker has armed its new R/C chopper with an IR transmitter and sensor, allowing for two to have laser dogfights in midair. If one gets hit, its power gets cut, sending it crashing to the ground. Cold blooded!

Oops.

IT was not quite a Star Wars death ray, but air force Top Guns accidentally focused high-powered lasers on to a civilian car in May this year - potentially endangering the eyesight of peaceful earthlings.
RAAF F/A-18 fighters from the Williamtown base north of Newcastle were conducting exercises near the NSW mid-north coast town of Forster when the incident happened.

The pilots thought their laser targeting system was turned off for the training flight.

Unfortunately it wasn't and the powerful light beams, known as class four lasers, were shone twice on to a road intersection for a total of 43 seconds.

Guys, remember to put your equipment into O.F.F mode first.

On June 21 a real-time optical link between a Mystère 20 aircraft, a satellite and the ground was demonstrated at the Paris Le Bourget airshow.

"Exceptionally clear" video footage was shown on the ground of the aircraft cabin and countryside below at respectable data rates.

These innovations have enabled Astrium to demonstrate exceptional system performance in an aeronautical environment:

Flawless 50 megabits/s transmission

Link acquisition in under a second

Pointing with an accuracy of better than 1 microradian (the equivalent of pin-pointing a person in Moscow all the way from the Paris airshow)