Dragon's Eye News

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.

Well, it turns out that one of the problems I was having with my green laser and the VRP-M film is my shutter.

When it opened it set the table to ringing for at least a full second.  My 2-4 second exposures were incredibly dim because they were getting fogged for the first second.  I found this out after setting up an interferometer (shown above, click for a larger picture) opening and closing the shutter while it was going.  The fringes really moved when the shutter closed but as no light would have been reaching the film, I didn't care about that.  Have it shake the table when opening was a problem though.

I tried all sorts of things to improve the isolation of the shutter and damp the vibrations it was putting out but in the end I had to give up and make a shutter from scratch.

I took a panel meter and attached a multi-layered piece of aluminum foil and used that reflect the incoming beam and create a beam dump on the inner surface of the meter housing.  Painting the whole thing black created a nice little box to keep the beam in.

After putting a couple of beads of silicone where the meter arm rests against the coil I ended up with a nice quiet shutter that didn't disturb the fringes at all.

It's being put through its first hologram-making test right now.

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.

OneNote is a great tool for note taking and information management. It also is a good tool for recording meetings and conversations. If you haven't heard about ON's ability to search audio recordings head over here to read more.

ON does a good job of indexing audio which can then be searched much as you'd search a text file.  This is especially convenient in cases when you know someone said something in a meeting but you don't know exactly when.  By indexing your audio you don't have to listen to the entire meeting again as long as the audio is of good quality.

What none of the marketing info covers are the laws that affect your ability to record those conversations and what you can do with those recordings after you've made them.

More after the jump.

I'd seen mention of this group before but never a description of how their laser tagging actually works.  Until I read the article in the NYT that is.

As Mr. Powderly neared the museum’s entrance, he jumped off the cycle and pointed it toward a bare stretch on a garage door across the street. Mr. Roth pulled a laser pointer from his pocket, and as he moved the laser’s green dot across the wall, a line of what looked like thick, drippy paint lit up its surface, roughly following the motion of his hand.

This actually sounds pretty darn cool.

Joining the crowd of cyclists, Mr. Powderly followed them as they moved through the honking streets of Brooklyn. In search of a spot to project their graffiti, they settled on the handball courts of McCarren Park in Greenpoint.

Mr. Powderly positioned the cycle to face the court’s gray concrete wall. Within a few minutes, someone had drawn a detailed sketch of a bicycle, and another person had traced an outline of an American flag.