Lasers & Holography

Northwestern University and BBN Technologies of Cambridge, Mass have demonstrated a technique for encrypting data with a little help from lasers.

The volume and type of sensitive information being transmitted over data networks continues to grow at a remarkable pace," said Prem Kumar, professor of electrical engineering and computer science at Northwestern's Robert R. McCormick School of Engineering and Applied Science and co-principal investigator on the project.

Continuity Central reports:

The combined QKD/AlphaEta system has been demonstrated in a nine km link between BBN headquarters and Harvard University in Cambridge, Mass. The AlphaEta encrypted signal carried OC-3 (155Mb/s) SONET data between the two nodes. A fresh encryption key of about 1 kilobit was repetitively loaded every three seconds. In a separate test, the AlphaEta encrypted signal was looped back multiple times to create an effective 36 km link where more than 300 consecutive key exchanges were demonstrated.

Not only do you have to worry about getting tagged with a laser while speeding but now you might just get a ticket for following too closely if you're using someone in front of you as a shield.

The Oregon Mail Tribune reports that they're testing a new system that will report the speed of a car as well as the distance between it any any car following it.

Dace Cochran, a patrol sergeant with the Jackson County Sheriff's office writes:

Here's what the updated lasers will be able to tell us:

• The speed of the first car.
• The distance from the laser operator to the first car.
• The speed of the second car.
• The distance from the laser operator to the second car.
• The distance between the two cars (front bumper to front bumper).
• The time difference between the two cars.

Once this comes to your state, assuming you aren't in Oregon now, be careful about using other people as ticket shields. Of course, you could always just slow down.

Electronics Weekly reports that Cascade Technologies, based in Stirling Scotland has developed a system capable of detecting explosives in tightly sealed packages, without opening them.

At the lab, we were sent a sample of explosives in a glass phial in an aluminium package, and that package had been through the post, company CEO John Fuller told Electronics Weekly. We could detect the explosives without opening it.

From the company's web site:

One such technique, known as Intra pulse spectroscopy, uses the laser in pulsed mode to facilitate its use over the wide range of environmental conditions typically associated with industrial monitoring. Pulsing the laser for up to a microsecond at a time causes instantaneous localised heating within the device, which results in a large frequency chirp. This chirp is harnessed to provide a near instantaneous frequency sweep through many spectroscopic features of interest.

Not literally, but budget cuts are taking it out of action.

Why do you care? Because it achieved a few firsts using lasers!

Less than a year after completing a $50 million project to repair and upgrade the San Diego-based research vessel, the Navy will decommission it Sept. 22. It is the country's last diesel-electric sub... The Dolphin had other notable firsts: sending the first successful submarine-to-aircraft laser communication and the first sub-to-surface e-mail.

optics.org reports

Scientists from Canada's National Research Council Institute for Biodiagnostics in Winnipeg claim to have developed a technique for measuring blood-flow velocity that is significantly cheaper and faster than existing methods.

Laser speckle imaging is used to monitor and map blood flow through the tissue by tracking minute changes in the skin caused by movement of the blood through the vessels underneath.

Having this information is important in determining if a grafted area will heal properly.

Laser speckle is an optical interference effect that's observed when laser light is incident on a rough surface, such as living tissue. The light and dark "speckles" are caused by constructive and destructive interference of the scattered light. The speckle pattern fluctuates if the illuminated area contains moving particles, like blood cells. Analysing these fluctuations yields information about blood-flow velocity.

Ok, so for the last several weeks I've had a functionally dead Spectra Physics 907 laser.

I managed to tweak it past the point of lasing and had to start the arduous process of learning to align this kind of laser from square one. I then spent the better part of two weeks trying to align the laser myself but could never get the beam quality back the way it was before I screwed it up.

What follows is what I've done so far to get my laser fully alive again. It's still not working but hopefully soon it will be.