Laser marking

An interview with Rofin-Baasel Inc. serves as a status report on the technology.

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An interview with Rofin-Baasel Inc. serves as a status report on the technology.

Editor's Note: Rofin-Baasel Inc. is a company on the leading edge of laser marking technology. John Derzy, general manager and Patrick Schlather, NE/MW sales manager, share their perspectives regarding the condition of today's marketplace.—DAB

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As with other industries in the United States, laser marking felt the impact of September 11th. Markets that were on the verge of expansion suddenly went on "hold." Others that were not in the forefront began to accelerate. Low-cost laser marking systems have entered the picture and new technologies are evolving.
John Derzy believes that the new directions have been both positive and negative, stating, "Perhaps the one area that was decimated by Sept. 11th was laser marking for parts traceability in aerospace. It had tremendous momentum until that point in time. The fall-off in travel, the airlines' financial conditions and the slowing of airplane deliveries pushed everything back in time, dramatically. However, a sleeper—the security market—is now rapidly expanding."

Pat Schlather is concerned with the influx of low-end lasers. He explains, "It has become a 'buyer beware' market because the customer sees a less costly unit as very desirable. They are only a few watts and generally small in size. To be air cooled, they are typically in the 3-10Ωrange; fine for some marking in specific materials only. The problem arises when a customer buys one to save money but then discovers that it won't handle all the applications he hoped to use it for. At our company, we thoroughly examine the customers' needs and then test the applications across our broad product line to help them access the various models' benefits to best obtain a sure fit."

Current technology is driven by the customers' needs. The ultimate goal of laser marking is to satisfy these applications. Rofin, for example, uses this as the defining guide to expanding its technology. A lot of the company's development centers on matching laser wavelengths and pulsewidths to specific needs.
Derzy offers this example; "In the semiconductor industry, if you were to place an identifying mark on the backside of a micro-ball grid array (BGA), which is basically a bare die, using the standard 1064-nm wavelength (red) a certain amount is transmitted through that device, which could debilitate that circuit. Using the green wavelength, you get virtually 100-percent absorption on that marked surface, and yet nothing transmitted through that could be detrimental to the device itself."

Schlather goes on to explain, "Narrower pulsewidths in the 10-15-ns range tend to yield good reactions in plastics without the affects of latent heat, produced by conventional lamp-based lasers with pulse lengths that can be from 100 to 300 nanoseconds. The reaction with the material happens in the first 10-20 nanoseconds and anything thereafter is latent heat that could actually destroy the initial work. Short-pulse lasers provide an aesthetically pleasing mark without requiring the extreme modification to the resin needed using a longer pulse laser."

Data matrix marking is a growing technology driven by industries that require more information to be displayed than is possible with barcodes.
"Data matrix technology allows embedding a great deal of information in a very small area. It is a checkerboard pattern having on and off bits that has a tremendous capability in terms of encoded information for automated tracking functions," explains Derzy. "It is possible to place a 60-character message in an area as small as one millimeter square. The user has the ability to adjust it to size needed depending upon available real estate. With laser marking, a cell can be as small as one dot diameter of the laser beam. Our MultiScan product can be used for marking on-the-fly in packaging industries."

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Figure 1. 2D symbology improves product tracking and accountability.
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The acceptance of laser marked 2-D symbology (see Figure 1) has increased in applications in product traceability to include many that formerly required labels or printing techniques.
"With laser 2-D symbology you no longer need the 90 percent or 70 percent contrast ratio to have a grade 'A' symbology for plastics, aluminum castings and different housings that previously required either ink print or labels," says Schlather. "Because of this, a wide range of industries is now using lasers for product tracking and accountability. It is particularly embraced by automotive parts suppliers, electronic PCB assembly and in medical instrumentation. It is already in the aircraft ATA2000 spec stipulating a 2-D data matrix code and the barcode 128 or PDF 417."

Derzy and Schlather share some sneak previews of what can be expected in the market in the future.
In the security area, R&D in laser pulsewidth has created lasers with the capability to mimic true black-and-white photography (see Figure 2). Using proprietary software, Rofin has taken this one step further and developed a way of embedding information into laser-created photographs that can be seen only with a specialized viewer. "Laser-marked data matrix codes can also be used for counterfeit protection," notes Derzy. "We can encrypt information that might look like a normal code but, unless the encryption algorithm is known, it is impossible to decode. The advantage of the laser is its programmability to easily change/update security devices."

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Figure 2. Embedded code information enhances security.
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The giftware marketplace is a prime market for laser/software combinations that import a picture and turn it into a 3D model inside of solid glass. Schlather sees the jewelry market as a great growth potential for this technology stating, "People want more personalization in a wider variety of jewelry items. Lasers have been accepted for welding and repair of jewelry, so the industry is very open to new applications. This is definitely an area where we expect growth."

Currently, marking lasers are limited to about 150 W. R&D in the area of diode pumping technologies is creating both higher-powered lasers to take advantage of the fast scanning technologies and "smaller" lasers that have capabilities well in excess of their compact size.

"Diode-pumped lasers have high beam quality with excellent pulse-to-pulse stability and long maintenance intervals," says Derzy. "However, diode pumping also allows us to use different types of crystals and resonator designs that offer new wavelengths or other characteristics that further enhance laser markers through reduced cost, reduced floor space and improved performance."

Derzy and Schlather summarize:
The only issue that could have a negative impact on market growth is the influx of single-application lasers. The assumption by users that these will handle multiple applications has a backlash that could hurt overall industry credibility. Buyers are encouraged to have suppliers of laser marking systems explain their products' capabilities and limitations to avoid misunderstanding.

Overall, however, the wide market appeal of laser marking tends to make the technology semi-recession proof. As one market declines another shows growth. The continuing development of new technology by companies such as Rofin stimulates the expansion of new markets, which, in turn, benefits all companies in the laser marking business.

Contact John Derzy and Patrick Schlather at Rofin-Baasel Inc., Boxborough, MA, by e-mail at Rofin-Baasel@Rofin-Baasel.com, or on the Web at www.rofin.com.

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