Gillette Corporation introduced the Sensor razor, which incorporated many unique components and novel approaches to design. One of these was the use of laser spot fusion welding. Each expensive thin platinum hardened stainless steel blade is joined to a cheaper rigid metal alloy support bar by 13 spot welds. The welds are made by using the energy in a pulsed beam of infrared light delivered from a solid Nd:YAG (neodymium yttrium aluminium garnet) laser with a power of about 250 W.
Gillette introduced the Sensor razor, laser processing engineer
Millions of blades are manufactured every day; each cartridge is welded in about one second. The MACH3 shaving system, Fig. 1.1, features cartridges with three blades that are welded using this technique.
Since 1994, Oras Oy (Rauma, Finland) has used lasers to mark its company and product logo on its bathroom products. Polymer tap levers are electroplated with layers of chromium and nickel. The product logo is indelibly branded by thermal vaporization of part of this layer by a writing beam from a continuous 85 W Nd:YAG laser. It takes between two and five seconds to write the logo, depending on the product. Each year, the covers and levers of millions of single lever taps, thermostatic bath units and shower components are laser marked.
Nelko Oy (Lapinlahti, Finland) a manufacturer of kitchen furniture, produces a range of wooden finishes, some of which can be tailored to individual tastes. Wood is a natural polymer composite that comprises strong fibrous chains of cellulose embedded in a matrix of softer lignin. The panel shown in Fig. 1.3 was laser engraved from a digitized image. Different colours and textures are obtained by varying the pulse length of light from an infrared carbon dioxide gas laser (CO2) and by using different gases to shield the interaction zone.
Modern kitchens provide industrial designers with opportunities to demonstrate their talents on a wealth of engineering materials: stainless steel sinks; wooden furniture; ceramic tiles and stove tops; tough resin mouldings; and granite worktops.
When the talents of an industrial designer are combined with the knowledge of a laser processing engineer, the results can be spectacular. Or they can go unnoticed – few are likely to show off their laser-welded refrigerator door, washing machine drum, or, least likely of all, kitchen sink.
The laser has made an outstanding contribution in many fields of medical science. Remarkable advances have been made in ophthalmology – the first user of medical lasers, and still the largest. Retinal attachment using a few watts of blue light from an argon ion gas laser brought the role of the laser to public attention. Today, laser-based cosmetic surgery probably commands the highest public profile. However, dentistry, gynaecology, urology, neurosurgery and many other disciplines have benefited from the minimally invasive nature of surgery that laser processing provides.
Laserin-situ keratomileusis (LASIK) is an ophthalmic procedure that combines laser processing and microsurgery. It is used for the treatment of nearsightedness (myopia) and farsightedness (hyperopia). A keratome (a device containing a high-speed rotating disc) is used to cut a layer of superficial corneal tissue (a natural polymer) about 0.15 mm in thickness, which is folded aside, Fig. 1.4. Corneal tissue is exposed to pulses of ultraviolet laser light (normally produced by an argon fluoride excimer laser), each of which removes a layer of tissue around one quarter of one micrometre (one thousandth of a millimetre) in thickness.
Movement of the beam over the eye is computer controlled for precision profiling. The ablation process is athermal; the energy of the ultraviolet radiation is sufficient to break molecular bonds, which provides exceptional accuracy. The total amount of material removed is normally less than the thickness of a hair. Myopia is treated by removing tissue from the central region of the cornea, which decreases its curvature to reduce the focal length of the lens. Hyperopia is corrected by removing tissue from the periphery of the cornea.
The flap, which acts as a natural bandage, is then replaced. The laser procedure is very brief – typically lasting for no more than 40 seconds – and is carried out under local anaesthetic. The complete treatment takes less than 15 minutes. The procedure is carried out in over 40 countries, and over one million people have been able to discard their spectacles