Lasers focus on materials processing at the smallest scale

06 Jul 2007

A recent workshop highlighted innovative optical techniques for micro- and nanomachining.

More than 40 industrialists and academics gathered at Cardiff University's School of Engineering this week for a one-day workshop to discuss the use of lasers for materials processing on the smallest scale.

Organized by the Association of Industrial Laser Users, the seminar included presentations on the current state-of-the-art in micro- and nanomachining, as well as informed speculation about future developments. Speakers from outside the laser industry also discussed how their businesses are driven by the constant need for miniaturization, a valuable chance for laser manufacturers to hear from people who are eager for laser specialists to machine ever-smaller structures.

Among the workshop's highlights:

• Malcolm Gower of Nanophoton Technologies began the meeting with a comprehensive overview of laser techniques for micro- and nanomachining, and the consequences of approaching the resolution limits of laser processing. He outlined the physics governing the focusing of laser beams, and the inventive methods available to reduce beam dimensions below the theoretical diffraction limit - the "optical tricks", as Gower described them.

He also discussed the concept of metamaterials, and the properties of a theoretical "superlens" made from a material with a negative refractive index. Such a material could allow image resolutions smaller than the laser wavelength, although such applications remain largely limited to research labs at present.

• James Pedder from Oerlikon discussed 2.5D and 3D micromachining techniques, and the use of solid-state and excimer lasers for different applications. The use of variable aperture masks and halftone masks to produce regular and semi-random surface structures in a range of plastics was demonstrated. Pedder also described the Synchronised Image Scanning process, in which the laser fires in synchronization with the workpiece movement, to produce patterns not achievable by other methods.

• Martin Sharp described the techniques being studied by the North West Laser Engineering Consortium for the manufacture of nanoparticles with fiber lasers. He outlined the existing techniques, including laser pyrolysis and laser ablation, and the advantages and disadvantages of each. This subject will be covered in more detail shortly on optics.org.

• Peter Myers visited from the opposite side of the industrial fence. A chromatography specialist and visiting professor at the University of Liverpool developing techniques to analyse ever-smaller volumes of chemicals, Myers' analytical equipment requires a variety of tiny capillaries, junctions and channels. He showed prototypes for next-generation separation techniques using centrifugal force, and complex electrophoresis devices on a tiny scale. Such prototypes are currently assembled using inventive but inelegant assembly techniques, notably the old-fashioned mechanical drilling of holes to introduce the sample tubes.

Myers' plea to the laser industry was straightforward: a call for the latest advances in laser micromachining to come to his aid, and by extension to the aid of other engineers whose businesses require constant miniaturization. A welcome message for all the laser innovators and specialists who were present to hear it.