Sci-Tech

Making lasers a bargain

As costs drop, lasers will replace cutting tools and medical equipment, Coherent CEO John Ambroseo predicts. Photos: Forty years of lasers at Coherent

In the movies, lasers lay waste to planets. But in reality, these focused light beams can do everything from clean your teeth to cut holes in T-shirts.

Coherent, one of the oldest laser companies, is celebrating its 40th birthday this year. (The name comes from the character of laser light, which is said to be coherent, or synchronized.)

While the company has spent most of the time crafting large lasers for semiconductor makers, Coherent is now promoting optically pumped semiconductor lasers: small, relatively inexpensive lasers that consume much less power. With these, you can bleach a faded tone into a pair of jeans or detect fingerprints at a crime scene. The company is also trying to enter new markets, replacing light-emitting diodes (LEDs) and lightbulbs in digital cinemas and rear-projection TVs.

Coherent CEO John Ambroseo talked with CNET News.com's Michael Kanellos about the declining cost of lasers, the folly of laser weapons and what the doctor has in store.

Q: Can you give us a quick overview of Coherent?
Ambroseo: We have 2,200 employees and have about $500 million to $600 million in annual sales. We do business in more than 80 countries, but our predominant employee base is here in the United States, with the highest concentration being in California. The next-largest group is actually in Germany.

Manufacturing in America. That's not something people expect.
Ambroseo: The skill sets for this industry developed largely in those two areas. Silicon Valley is where lot of the early action took place in lasers and photonics. And there's been a long-standing investment by the German government in photonics. It has been investing for 20 years in educational programs and research centers and the like. Over the years, we've acquired three companies in Germany.

Coherent lasers

We cater mostly to the high end, but we're actually starting to move more into volume applications, which for us would be sort of the thousands to 10,000 pieces. We are finding out now that lasers are starting to replace traditional tools.

Such as?
Ambroseo: Well, one of the things that we've broken into in the past few years is the clinical-biology market. Procedures like DNA sequencing, blood analysis, drug discovery. (Using lasers for such procedures) has been done for a long time, but the clinical application of them has been hindered because you have these very large, bulky devices with inefficient light sources.

In the past few years, we've figured out how to turn water heaters or blow dryers into really efficient light sources. This (holding up an aluminum box the size of a paperback) is what's called the Sapphire Laser. The Sapphire Laser is the first in a completely new class of devices.

Let me start by saying that every light source--whether it's a laser, the sun, a lightbulb or a match--the color of light that comes out of it is determined by the materials it's made of. If you change the gas mixture or the gas pressure in these lamps, they emit a different a color.

About eight or 10 years ago, we got involved with something called optically pumped semiconductors, and the optically pumped semiconductor technology is vastly different because it's essentially a designer laser. It's the first time that you could specify both the color and power that came out of the device. You are no longer bound by the physics of a specific material. As a consequence, this box is 10 to 100 times smaller than the products replaced. It's somewhere between 50 and 100 times more electrically efficient.

The technology was initially developed at Lincoln Laboratory, which is associated with the Massachusetts Institute of Technology. We acquired the base technology from the group that spun out of Lincoln and commercialized over the last decade.

One thing I liked in your museum downstairs is a laser that's used for finding fingerprints. How does that work?
Ambroseo: You can do it one or two ways. You can use what's called bioluminescence. Biological samples and even a lot of nonbiological samples will actually have a fluorescence when radiated with certain colors of light. Many times, you don't see this because you have a white light source, so it just washes out everything else. But when you use a specific color of laser combined with the ability to block out all the other colors, you can then see the fluorescence return.

What some of these labs do is use a dye or a reagent that they can spread the scene with that binds selectively and glows. The benefit here is that you can preserve the chain of evidence, and you can sweep an entire scene rather than saying "OK, I've found a suitable physical piece of evidence. I'm going to take this back to the lab, and I'm going to test it."

The version that you saw downstairs we just launched in the last few months. It's based on an OPS (optically pumped semiconductor) laser, and the biggest claim to fame is that it's the first truly manned portable device. These things are so electrically efficient that you can battery-power them for an hour or two.

It holds two to four commercially available batteries. We didn't do the stupid thing with a custom battery. We have a couple of agencies coming to back to us and saying, "You know, we paratroop people in with this equipment, so whatever it is--40 pounds or 45 pounds--it needs to weigh half that." So they want us to do a custom design with a magnesium box or magnesium frame so it can fit in a backpack, jump out of a plane or rappel out of a helicopter.

What are the different-colored OPS lasers used for?
Ambroseo: The green is used in display and imaging. The blue is used for many of those applications and as a bioinstrumentation tool. The yellow is gaining a lot of attention from the medical therapeutics market, because yellow turns to be an ideal color to use for things like treating glaucoma photocoagulation. It turns out that hemoglobin absorbs green better than it absorbs yellow, so you get a lot more collateral heat or a lot of situational heating and potentially collateral damage with green, whereas the yellow gets more selectively absorbed by your targets.

By varying the power of the laser, you can go from cutting power to bleaching power.

It's the same concept when you put a flashlight on your hand. You'll see red come around the edges. You don?t see the green or the blue coming through because it's all getting absorbed in your skin.

Then there is colonoscopy. Do you thinking I'm kidding? I'm not. It turns out that the most frequent cause of death in colonoscopies is a rupture resulting from a biopsy. If you stick a needle in--

OK, I follow you.
Ambroseo: Right, and so they're looking for way to reduce that and also to take away the anxiety portion of the biopsy. When they pull a tissue sample out--they're pulling parts out of people all the time in these things--you have to wait about a week or 10 days to get the lab results back. That?s incredibly nerve-racking. So this group goes in using the same endoscope, and at the same time, it has a three-fiber bundle that's inserted as well.

One fiber carries the laser light, they illuminate the whole area, and it allows them to create a three-dimensional image of the colon. One fiber with the laser, one fiber shoots the reagent, and a third fiber picks up the return signal. These three fibers are a few hundred microns, so in theory it's a much less painful process, because they would have to insert a much smaller device. They?ve treated between 200 or 300 patients with this already.

What other applications are you moving into?
Ambroseo: This may seem trite, but there's actually a minirevolution in textiles. When you cut materials, you use a blade, scissors, whatever it may be. If you're a process engineer, you have to design a process around the weakest point in the lifetime of that blade, which is usually the last cut it makes. What factory managers and process engineers have found is that if they replace the blade with a laser, they no longer have that weakness.

The other thing is that by varying the power of the laser, you can go from cutting power to bleaching power. So instead of having to bleach denim, for example, to get a certain look, they now just vary the power of the laser. The jeans, with all the little holes and everything in them--the way they do those is they fray the material by shooting in bursts.

One of our customers showed us a sample. It took them about 30 seconds to make the jeans, and they charged $400 for them.

Now if you really want to start of think of futuristic, you can look at another technology that's well-known, which is optical tomography. This is where you have a 3D body and scan it with laser light to reconstruct a model of it. You get their precise measurements, and you download it to a cutting system, and then you have a custom suit for the cost of about one off the rack.

Are you guys involved in weapons or defense systems at all?
Ambroseo: We get calls all the time, and it's not that we're unpatriotic and it's not that we're pacifist. But at the end of the day, it has to make sense, and there are a lot of sort of screwy ideas about how to deploy energy weapons, which have no physical basis, and we cannot chase pipe dreams.

What are the some of these ideas that are being thrown around out there?
Ambroseo: One of the ones that keeps reappearing periodically is laser glide slopes. The idea is that you would project these laser lines into the air so that a pilot coming into a runway or carrier can visualize the glide slope and therefore make a much more precise landing.

That's great under perfect atmospheric conditions. But if it's raining, if it's snowing, if it's too dry, it's doesn't work. We have guys over the years who have said, "I know the perfect application: I want to project the first-down mark on a (football) field." Do you understand that if it's raining, nobody can see it?

The whole "Star Wars" project. They made a lot of progress, and maybe they have platforms up that are working--who knows--but the challenge of being able to focus a beam of light through the atmosphere, over a curve and all these other things--these are nontrivial problems.