As the editor of Photonics Tech Briefs, I cover laser technology for a living. They’re pretty fascinating devices, but that doesn’t mean I ever wanted to have a laser beam shot into my eye. Unfortunately, Father Time and our own bodies do not always give us a choice.

I was recently diagnosed as a prime candidate for narrow angle glaucoma. According to my optometrist, fluid in the eye normally drains through the space, or angle, between the cornea – the clear element covering the front of the eye – and the colored part of the eye, called the iris. In some people, like me, as we get older the lenses in our eyes continue to grow while the anterior chambers get shallower, causing the drainage angle to narrow. This causes pressure in the eye to increase. If it gets too high, it can result in a very serious condition known as acute angle closure glaucoma, which can send you to the emergency room with severe eye pain, nausea, vomiting, blurred vision, and some other very unpleasant symptoms. If they can’t relieve the pressure immediately, it could result in permanent damage or loss of vision.

The way to prevent that is a relatively simple medical procedure called laser iridotomy, which involves using a precisely focused laser to burn a tiny microscopic hole in the iris, causing it to move away from the fluid drainage area, thereby relieving the pressure. Notice I said “relatively simple” because that’s how the eye surgeon described it. As for me, getting shot in the eye with a laser sounded anything but simple.

The laser used for this procedure, at least in my case, was a Nidek combo YAG/green laser that combines their YC-1800 ophthalmic Nd:YAG laser and GYC-1000 green laser photocoagulator into one machine. According to my surgeon, having both types of laser combined in one system allows for “on the fly switching.” I was about to ask him why that’s important when I realized his answer my only increase my fear factor, so I just let it go.

The procedure, which takes all of about 2 or 3 minutes, is painless, but it does involve some degree of discomfort. After anesthetic drops are placed in the eye and the patient’s head is positioned on the machine, a small device is placed over the eye to hold it open throughout the procedure. The patient is then instructed to focus their other eye on some point – the doctor’s shoulder, for example – told not to blink, and the procedure begins. For the next few minutes the eye being treated endures a series of very bright flashes of light – like a strobe light – and an uncomfortable feeling of pressure being exerted on the eyeball. I counted a total of 62 flashes in all, which is a lot when you’re trying not to blink…or panic. When it was over, vision in that eye was slightly blurry and it felt irritated, like a bad case of dry eye, for several hours. After that everything was fine.

Afterwards, I asked my doctor about the flashes. As he explained it, that was the laser being triggered. The hole in the iris is not formed with one long, continuous burst, as one might assume from watching old sci-fi movies. Rather, each burst removes a microscopic amount of material until the hole is created. He seemed somewhat surprised when I told him how many flashes I’d counted.

I don’t know about you, but any surgical procedure involving my eyes terrifies me. I mean, if a doctor operating on your leg makes a mistake, you may walk with a limp for the rest of your life, but if your eye surgeon makes a mistake…

I understand before the advent of lasers, they used to perform iridotomies by hand. Isn’t technology wonderful?

Day one at the Medical Design & Manufacturing (MD&M) West show in Anaheim, CA was bustling with energy. Nearly everyone I spoke with said that they had found themselves happily busy throughout the day.

One nice part about meeting people at trade shows is that you might come across information you would never have gleaned from a simple press release (or information that never made it into the press release in the first place). For instance, although I was aware that NASA and GM had developed the highly advanced “Robonaut 2″ robot for space and automotive applications, I had no idea that Quickparts was involved in the process as well — until I spoke with their representatives at today’s show. Roughly speaking, Quickparts supplied custom parts for the Robonaut 2′s head and body, while GM was involved mainly with the development of the robot’s dexterous arms.

In other news, one innovation that caught my eye was the Noble UltraLight from Norman Noble. The brochure features a man in swimming gear making a snow angel, underneath the words, “Our New Laser Technology is Cool.” This athermal laser machining process was developed for applications that require intricate cutting without thermal damage to the material – such as the manufacturing of stents or a number of other medical devices. Hopefully I’ll find something just as “cool” tomorrow.

NASA Spacecraft Zaps Venus with a Laser

On June 5, NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft flew past Venus just 338 km above the planet’s surface and shot a laser into the clouds. Although MESSENGER is on a mission to Mercury, the spacecraft must pass by Venus for a gravity assist en route. In passing, researchers hope to learn a few things about the planet with sulfuric acid clouds, a choking carbon dioxide atmosphere, and a surface hot enough to melt lead.

“We are treating the Venus flyby as a full dress rehearsal for the first flyby of Mercury in January 2008,” said Sean Solomon, the mission’s principal investigator at the Carnegie Institution of Washington. “All of the spacecraft’s science instruments will be turned on during the flyby.”

The experiment aims to measure the location of Venus’ cloud decks. The Mercury Laser Altimeter (MLA) was designed to map the rocky topography of Mercury, but MLA turns out to have some nice properties for the study of Venus. In addition to the laser, MESSENGER will scrutinize Venus using high-resolution cameras, a suite of spectrometers ranging in wavelength from infrared to gamma rays, an energetic particle counter, and a magnetometer.

For more information about the MESSENGER mission, including a photo gallery and movies, click here.

Laser-Based Device Offers Alternative to Video Surveillance

The Laser-Based Item Monitoring System (LBIMS), developed by researchers at the Department of Energy’s Oak Ridge National Laboratory, balances the need for high-resolution monitoring and personal safety with confidentiality and personal privacy. Using low-cost reflective tags placed on objects, LBIMS maps the precise location of high-value items. The laser can scan many points per second and can detect small changes — less than a centimeter — in the reflected signal, meaning tampering can be detected immediately.

The precision of the system is made possible by a high-resolution, two-axis laser scanner capable of looking at a 60-degree field of view in 0.0005-degree increments, dividing the field of view into more than 10 billion individual pointing locations. A camera with comparable resolution over the same field of view would require a 10,000-megapixel detector.

Existing light detection and ranging (lidar) systems, which use scattered light, are optimized for detecting human-sized objects. Another competing technology is bar codes and radio frequency identification. In addition to being susceptible to jamming, the bar code reader or RFID antenna must be within a few centimeters of the tagged object.

Click here for more information.

Motion Control Technologyâ„¢, a bi-monthly supplement to NASA Tech Briefs, contains a section called Applications, which reports on motion control components being used in the field. Here’s an Insider sneak peek at one of the technologies covered in the upcoming June issue:

Scales Work as Part of Thermonuclear Ignition Target Assembly
The National Ignition Facility (NIF), part of Lawrence Livermore National Lab (Livermore, CA), constructed a system of lasers ending in a chamber ten meters in diameter to house tiny fuel capsules that are subjected to a high-energy pulse, setting off a small thermonuclear burst. The target assembly machine, built by ABTech (Swanzey, NH), used linear scales from HEIDENHAIN Corp. (Schaumburg, IL).

With an accuracy of up to 4 millionths of an inch, the 5-axis assembly station is an air-bearing machine that includes mechanical arms with the ability to slide into position without friction. The system is capable of positioning the target shell halves in locations within 0.1 µm. The scales are exposed linear encoders capable of small, precise measured steps to 0.005 µm. The system is completed with a high-resolution camera and surgical microscope that provide views of the mating components.

The new target design has allowed NIF to create thermonuclear ignitions mimicking conditions found in the Sun or an exploding nuclear event. The primary mission of NIF will be to attain fusion ignition in the laboratory, exploring fusion’s potential as a clean, long-term energy source.

Look for this application in the June issue of Motion Control Technology.

Click here to view previously published Applications

Click here to learn more about HEIDENHAIN