Deja-vu all over again

Wuhan, China — Who says it's not a small world?

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Wuhan, China — Who says it's not a small world? While visiting Goldensky Laser Co. Ltd. (that's golden sky, not a Polish laser company) this writer was invited to glimpse the discharge pattern of a multi-kilowatt cross-flow CO2 laser being built by this company. "It looks like a multi-pass, multi-pin discharge resonator," I said. It is, I was told by the company's Board Chairman Dr. Quing Ming Chen. He went on to explain that he developed this particular laser while he was the Dean of the School of Engineering Science at Huazhong University in Wuhan.

"I co-developed this with the assistance and guidance of Dr. Arthur Kantrowitz who was teaching at the University in 1998," he said. "What a coincidence," I said, as I too worked with Dr. Kantrowitz in the early 1980s while he was Chairman of the Board and I was Director of Marketing and Applications for the Avco Everett Metalworking Lasers group. At that time we were exploring the market for a smaller version of Avco's famous HPL lasers, which were rated to 20 kW, and Kantrowitz suggested that we consider a multi-pin discharge resonator design, which employed more than 500 pins, each with its own ballast resistor.

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Left to right, William Yim, senior vice-president of the Hong Kong Optoelectronics Association, Dr. Qing Ming Chen, chairman of Goldensky Laser, David Belforte, ILS Editor-In-Chief, and Dr. H.C. Man, associate professor Hong Kong Polytechnic University and ILS contributing editor.
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A prototype was built and debugging of the design began before Avco decided to sell the Metalworking Laser group as it moved out of the commercial laser business. Work stopped on the design, which it was felt was too iffy for the industrial world.

You can imagine my surprise to see a 450-pin version working and to be told that 40 of these units had been sold in 2003 primarily for welding carbide saw blade teeth and other industrial applications.

Goldensky has licked the ballast resistor problem now guaranteeing 10 years on this part of the resonator. As a consequence this is a popular laser in China where high-power units such as the fast-axial flow devices from others are too expensive for the average buyer. A cross-flow laser costs about 1/4 that of a fast axial-flow unit at the same output power levels. And the Goldensky unit produces a TEM00 beam delivering 3 kW from a 3.5kW output.

Goldensky is a major supplier of CO2 lasers for cigarette filter paper perforating. For those who forgot, this application was big in the U.S. in the 1980s before this country decided to get healthy. In China, like other developing nations, smoking is rife and hundreds of lasers have been sold to perforate small holes in the filter to let air in to condense out the tars in the filter. I asked if the end of this market was in sight and was told that the undeveloped nations would provide a market for years.

Asked if I had any regrets about abandoning the Avco concept, I had to admit that it was about to be replaced by high-power FAF units anyway. And that I realized that timing was everything in life. More power to Goldensky, which has a powerful guiding principal: "Developing high technology—actualizing the industrialization." —DAB

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