Science: Big players for a disc-driven decade: Nimbus took a big risk 10 years ago but now has a ticket to ride the CD boom, says Susan Watts

Would you like to scratch and sniff your compact discs? Bananarama with a hint of fruit, perhaps, or a whiff of sulphur for Tchaikovsky's 1812 Overture. Meatloaf might not be so appealing.

Smelly CDs were one of several 'daft' ideas to come out of a recent brain-storming session at a small technology company in Wales. Now Britain's largest CD maker, Nimbus Maufacturing produced the first CD made in Britain in 1984. Nimbus, based in Cwmbran, employs only 300 people, yet has gained a powerful reputation as source of some of the world's most innovative developments in CD technology.

Among Nimbus success stories is the hologrammed CD. These have 3D images etched into their surfaces. Some are of the sparkly, shiny variety. Others are similar to those on credit cards, and are designed to discourage counterfeit CD manufacture.

Nimbus' success can be traced to one very high-risk move in 1984, when it switched its entire production from LPs to CDs just a few months after the first CD went on sale in the UK.

Compact discs grew out of an earlier technology known as Laser Disc. These were 12-inch platters which used analogue techniques to record and play music. Sony and Philips adapted Laser Disc independently to accommodate digital processing. They pooled their expertise, introducing the first five-inch CD to Japan in autumn, 1982, and to Europe (including the UK) in March, 1983.

The initial catalogue of 80 titles was a hotch-potch of rock, pop and classical music, with Culture Club one of the earliest pop releases and Christmas Carols from St George's Chapel in Winchester one of the first classical titles. These days, there are between 10,000 and 15,000 titles available to CD customers.

Sales of discs during the first two to three years, were very slow. Record companies were reluctant to release albums by big-name artists on CD as well as vinyl and cassette.

Things changed when the players were integrated into affordable hi-fi systems in about 1985. Manufacturers now sell around 450 million CD players worldwide every year, and 1.2 billion CDs. Sales of cassette decks and tapes are about the same, with vinyl sales an insignificant minority.

Nimbus produces both audio CDs - still the bread and butter of the industry - and the newer CD-Rom (Read only memory) discs, which promise a whole new market for CD technology.

Pop music artists are using CD- Rom to create music videos with added text and graphics as well as images and sound. The company is also poised to exploit another potentially lucrative CD market, producing discs with computer software to replace the traditional floppy discs in use today. Technical staff at Nimbus reckon that within two years, all computer software will be distributed this way.

The company is one of only nine CD manufacturers in the UK, and one of only two not allied to a record company. Nimbus claims its edge on competitors is in the design of the machines it uses to produce 'master' CDs. The Nimbus manufacturing plant differs from others in that its lasers can be controlled manually, allowing operators to tweak the focus of the laser, and its track and pitch, to ensure the best reproduction.

The production plant in Gwent operates under clean-room conditions normally associated with hi-tech microprocessor production. In fact, pits in a CD surface (just 0.3 of a micron wide, 1.3 microns long and 1.6 microns deep) requires work at scales 10 times smaller than chip manufacture.

Nimbus staff resemble astronauts. They wear full bodysuits because the air purity of the plant is religiously controlled. Some sections of the plant are guaranteed as having no more than 100 particles half a micron wide or larger per cubic foot of air. A human hair is about 100 microns thick, and for comparison, country air may contain a million such particles in the same volume, and city air two to five times this.

People shed millions of skin flakes and clothing fibres every minute - someone standing up generates about 10 million particles. People in the Nimbus clean rooms are told not to scratch or rub their faces, to help minimise the particles they drop.

Raw music comes from record companies and is fed to a helium cadmium laser, which etches the digital code on to a thin photographic coating on the surface of a 12-inch glass disc. This process creates a pristine template of the five-inch CD in the centre of the glass master. The master is then developed, to dissolve away the exposed areas to form minute pits.

The operator then coats the pitted glass master with a thin layer of silver, to grow a metal master or 'stamper'. This contains bumps instead of pits, and goes into the injection moulding machine that churns out the plastic CDs. These are coated with reflective aluminium, then the whole lot is encased in lacquer to keep air out.

The plant can produce 20 to 30 master discs a day, and generally turns out about 140,000 good discs a day, rejecting 7,000. An outside contractor hopes to find a way to recycle the polycarbonate plastic from rejects.

(Photograph omitted)