13

Mar

Show spotlights newest laser technologies

March/April 2013 Volume 6 Issue 2

Ronald D Schaeffer - PhotoMachining

Ronald D. Schaeffer
CEO, PhotoMachining, Inc.
rschaeffer@photomachining.com

laser welding

Laser welding of optically clear polymers was a hot topic at Photonics West. Image courtesy Fraunhofer ILT.

The laser world descends each year on the Photonics West conference and exhibition. The event is hosted by SPIE, an international society devoted to advancing biophotonics, biomedical optics, industrial lasers, optoelectronics, microfabrication and green photonics.

I attended the 2013 installment, held Feb. 2-7 in San Francisco. Following is a short report on some of what I heard and saw.

Let’s start with the main buzz: ultrafast-pulse lasers (UFPLs), defined as any laser with a pulse length in the picosecond or femtosecond range. These lasers have been used in research laboratories for a long time. But it is only in the last few years that UFPLs have significantly penetrated the industrial marketplace—a result of their now being able to operate at high average powers and with increased reliability.

In an invited talk, the president and CEO of Amplitude Systèmes (www.amplitude-systemes.com), Eric Mottay, estimated that the current UFPL market exceeds $400 million annually. He cited glass processing and micro- and nano-texturing as two applications that will see significant growth in the coming years, due to the increase in available average power.

Amplitude Systèmes, based in Pessac, France, builds femtosecond lasers with an average power output of more than 100w.

Lumera Laser GmbH’s (www.lumera-laser.com) director of sales and marketing, Dr. Dirk Müller, said he expects market expansion in tempered-glass cutting (such as displays), microvia drilling and large-area surface alteration.

Lumera, acquired at the end of 2012 by Coherent Inc., Santa Clara, Calif., delivers hundreds of UFPLs annually that have pulse lengths in the 10-ps range and are used for precision manufacturing. The company featured a new product at Photonics West called the Staccato laser. It has a 1.5-ps pulse length, which is about the shortest pulse possible without employing a chirped-pulse amplifier.

laser stentlaser points rofin

A shorter wavelength decreases the spot size on target, which offers advantages when processing polymers, such as this stent (top) cut with Rofin-Sinar’s StarFemto FX. Image courtesy Rofin-Sinar.

Also on display in San Francisco was the StarFemto FX laser from Rofin-Sinar Inc. (www.rofin.com), Plymouth, Mich. Rofin Director of Industrial Micro Sales Mike Armas said the advantages of the StarFemto include single-pass cutting, sharper edges, a wider processing window and three to six times faster cutting speeds.

The StarFemto offers users adjustable control of the laser pulse length, from 300 fs
to 10 ps in the fundamental, second and third harmonic wavelengths.

Even with extremely short pulses, it is frequently beneficial to use a shorter wavelength in order to decrease the spot size on target. This has clear advantages when processing polymers, such as stents, Rofin reports. Shorter wavelengths also help when processing metals like Nitinol, allowing material up to 0.5mm thick to be cut at 2.0mm per second.

The Lithuanian laser company Ekspla (www.ekspla.com) showed its Atlantic HP high-power picosecond laser. The 50w power output in the fundamental wavelength is not industry leading, but, according to the company’s U.S. sales manager, Jimmie Bates, the laser costs about one-third less than competitive products.

I found Ekspla’s pricing interesting because, on a dollars-per-photon basis, UFPL technology isn’t cheap. The key to making the technology viable in industrial applications is providing short pulses, high powers and bringing the prices down.

Currently, UFPL prices are roughly three to five times higher than nanosecond lasers. But if the price of a UFPL were reduced to that of a nanosecond laser, and the reliability and laser lifetimes were similar, there would be very little need for ns lasers in the industrial marketplace. This is not presently the case, so higher-power ns lasers continue to be introduced.

One of them is Quasar, a hybrid fiber laser that is part of Newport Corp.’s Spectra-Physics brand. Output powers over 40w can be realized at 355nm (up to 500 kHz), and the pulse width is variable.

A key benefit of ns lasers is they tend to be more robust than UFPLs, facilitating 24/7 operation. According to Dafydd Thomas, business development manager at Newport (www.newport.com), Santa Clara, Calif., the company is targeting applications such as printed-circuit-board cutting and drilling, silicon-wafer dicing, ceramic scribing and glass cutting.

IPG Photonics Corp. (www.ipgphotonics.com) showed new products that directly target the micromachining market. Variable-pulse-length, low-nanosecond lasers that are able, in some cases, to compete directly with picosecond lasers were on display along with short-pulse, high-repetition-rate ultraviolet lasers.

The micromachining market is clearly a priority for IPG, Oxford, Mass. Further evidence of this was its recent acquisition of micromachining systems builder J.P. Sercel Associates, now incorporated as IPG Micromachining.

At MD&M West, a show held in Anaheim, Calif., shortly after Photonics West, IPG displayed three new laser workstations. The one that generated the most interest incorporates a 120w thulium-fiber laser. The unit’s long-wavelength laser (1,940nm) was being used to weld optically clear polymers without special absorbers. The intrinsic focusability of this source enables noncontact welding of the newer polymer-based microfluidic devices.

laser points spectra physics quasar

Quasar is a hybrid fiber laser that’s part of Newport’s Spectra-Physics brand. It features TimeShift technology, designed for “programmable pulse profiles to deliver the ultimate in process speed, flexibility and control,” the company reports. Image courtesy Newport.

Along with the BPA (bisphenol A)-free Tritan copolyester material IPG used for demonstration purposes, other materials, such as phthalate-free substitutes for PVC, also can be welded.

A big debate during the show was whether fiber lasers or direct-diode-laser processing will predominate in the coming years. Advantages of direct diodes include compact size, high wall-plug efficiency (> 40 percent), robust design and insensitivity to back reflections. The focusability of these lasers is poor at present, and it’s hard to frequency-shift them. But high powers are currently available in the fundamental frequency.

According to Wolfgang Gries, CEO of Direct Photonics (www.directphotonics.com), Berlin, these lasers can be used for many welding and joining applications in the automotive, photovoltaic, micromechanical, medical and consumer electronics markets.

In contrast, fiber lasers have excellent beam quality, and therefore high focusability, making them a good
choice for higher-precision micromachining applications. In addition, fiber units can be frequency-shifted to shorter wavelengths. Their main drawback is that using the fiber as the oscillator is slightly more complicated. Then again, this also can be a benefit, as the fiber can be used as the beam-delivery vehicle.

The many new technologies on display at Photonics West and MD&M West reminded me that it’s very cool to be involved in an industrial market where the tools (expensive toys?) of our trade are constantly changing and developing, giving us more flexibility in the way we process parts and in the materials at our disposal. µ

— R. Schaeffer