Month: March 2007

Laser mapping the San Andreas fault

After a year, engineers with the University of Florida, the University of California at Berkeley as well as other engineering teams, efforts to laser-map the San Andreas fault are proceeding well with the goal of completing the mapping in another year.

The work is part of an effort to improve earthquake prediction and uses a plane-mounted laser to map the fault with higher precision than ever before.

A small airplane carries a laser that emits thousands of pulses of light each second toward the ground. The pulses hit and scatter back to a sensor, allowing software to gauge the distance between the plane and the terrain, pinpointing the altitude of each target point. When combined with GPS coordinates gathered in part by ground crews, the system also allows the software to determine the latitude and longitude of each identified point.

The result: a highly accurate three-dimensional map that looks something like a photograph, although trees and other features of the terrain can be stripped off to reveal only the bare essentials on the topography.

Dolmen work II

The dolmen is moving along (slowly, but moving) and last night I did a reflection color test to find out what concentration of TEA (triethanolamine) to use to get some interesting colors in the final hologram.

As a test I prepared some 2, 3, and 4% solutions of TEA and cut up a 4×6" piece of film into three sections.

the TEA was fleshly prepared and still warm and each piece of film was soaked for about a minute, squeegeed and left to dry for 30 minutes in my drying box.

The subject was a simple background that I could use to easily judge the differences in color.

After a 10s exposure the strips were developed in JD2 and bleached with EDTA and dried.

I ended up with a range of colors from yellow-red to gold that should work well in the final hologram.

At the moment I’m thinking of using a subtle range of colors rather than the more easily made red/green/orange I was thinking of. Something more along the lines of orange for the moon, golden for the terrain and a fire red for the inside of the dolmen where a fire might be.

With luck I’ll do the masters this weekend

New blue-violet laser

Researchers at UCSB led by Shuji Nakamura, winner of the 2006 Millennium Technology Prize have developed a new way to produce laser diodes that put out blue-violet light.

in fact, these are the world first nonpolar gallium nitride blue-violet laser diodes.

The nonpolar blue-violet laser diodes have numerous commercial applications, including high-density optical data storage for high definition displays and video, optical sensing, and medical applications. Because of the shorter wavelength of emission in these devices, they can accommodate higher densities of optical storage than conventional red-laser based systems.

Said Nakamura: "Our initial results of the first violet nonpolar laser diodes with a low threshold current density demonstrate a high possibility that current c-plane violet laser diodes used for HD-DVD and Blue Ray DVD could soon be replaced with nonpolar violet laser diodes, which require lower operating power and have longer lifetimes.

Dolmen work

It’s been a while since I’ve really been in the lab. After the first of the year I got really caught up in the Irish dancing events that Susan and I are involved with, did some travelling for work and then got sucked into the Irish dance St. Patrick’s "season."

Finally there’s a lull and I can get back to working on a dolmen hologram that I’ve had on the back-burner for three years.

Continue reading Dolmen work

Using a guide-star laser to find bullets

The Gemini Observatory has been using laser generated guide stars as part of their adaptive optics program for a while but they’ve recently release some stunning images of the Orion nebula featuring supersonic "bullets" of gas and their associates wakes through the nebula.

"What I find stunning about the new image is the detail it shows, which was blurred out in any previous studies, revealing the structure of the bullets and their trailing wakes as they run into the surrounding molecular cloud," said Michael Burton of the University of New South Wales who, along with the late David Allen (Anglo-Australian Observatory) were the first to suggest the origin of these spectacular bullets 15 years ago. "This level of precision will allow the evolution of the system to be followed over the next few years, for small changes in the structures are expected from year to year as the bullets continue their outward motion."

The exceptional resolution of the new image was made possible by
adaptive optics technology in place at Gemini Observatory. With a laser
guide star as a reference and a rapidly deformable mirror for real-time
correction, astronomers can compensate for most of the atmospheric
distortions that blur the near-infrared image of a star whose light
reaches the telescope’s primary mirror. The system deploys a
yellow/orange solid-state sodium laser that produces the artificial
guide star by exciting and causing a small column of sodium gas about
90 kilometers (56 miles) up in our atmosphere to glow. The artificial
star it creates becomes a reference star for the adaptive optics
system, and allows it to determine how the atmosphere distorts the
incoming near-infrared starlight.

Terahertz lasers for security

Sandia National Laboratories has continued work on devices for scanning for hazardous and toxic materials hidden in packaging and clothing and is on track for completion of the Terahertz Microelectronics Transceiver Grand Challenge.

These tiny lasers are semiconductor sources of terahertz radiation capable of output powers in excess of 100 mW. Previously, such powers could only be obtained by molecular gas lasers occupying cubic meters and weighing more than 100 kg, or free electron lasers weighing tons and occupying entire buildings.

NTIF 2007

The North Texas Irish Festival 2007 was a blast. Preparing for and performing during the St. Patrick’s season has kept me busy so I haven’t been blogging much but things are slowing down so look for the updates to increase.

For Susan and I NTIF started out with a workshop held by Claire Zucker on clogging. It was very Sean Nos-like and quite a fun workshop.

From there we performed with the Emerald School (lots of video taken there), ran a dance workshop where we taught several figures from the Kilfenora Plain Set and followed up by calling the three-hour ceili to close out the festival day.

On Sunday we performed again with the Emerald School and then followed up by wandering around listening to music and shopping.

One new group (to us anyway) that we look forward to hearing more from is Sliabh Notes.  They definitely play music that makes our feet want to start moving around.

More pictures and video are available in our gallery.