Analogue recording A recording technique that makes a physical copy of sound waves. For example, the grooves in a record are a copy of the vibrations in an original sound.

Barcode A black and white pattern, scanned by a laser to reveal coded data. Black areas absorb the laser beam, but white areas reflect it back. The pattern is then recognized by the barcode scanner.

Blu-ray disc A disc similar to a DVD but read using blue laser light. Because blue light has a short wavelength it can read very tiny pits. Blu-rays have many more pits than DVDs and hold over five times more data.

Compact disc (CD) A plastic-coated aluminium disc used to store digital data such as sounds. On the surface of a CD, flat areas called lands and shallow dips called pits represent binary digits. These are detected by a laser beam in a CD player.

CD player An electronic device that plays back sound recorded on a CD. As the disc spins, a laser detects the pattern of pits and lands on the CD’s surface. This is converted back into the original electric signal, which is amplified and sent to speakers.

CD-ROM (Compact Disc Read-only) A type of CD holding data that can be read by a computer but cannot be changed.

Digital recording A recording technique that converts sound waves into an electrical signal, digitized to create a string of binary numbers.

DVD (Digital Versatile Disc) A plastic-coated aluminium disc, used to store digital sounds and images. Because the laser beam of a DVD player is very fine, it can focus on tiny pits and lands. This means a DVD can have more pits and lands than a CD and contain seven times more data.

Gramophone An early recording device, invented in 1877 by Thomas Edison. To record, a sound vibrated a needle, cutting a groove in a foil surface. To play back, the needle moved along the groove, vibrating a diaphragm to reproduce the sound.

High-power laser A laser that can be focused to create intense heat. High-power lasers are used for accurate cutting in industry and medicine.

Hologram A three-dimensional image, created by lasers. To form a hologram, a laser beam is divided in two. One beam is shone at photographic paper; the other is directed at the object, from where it bounces on to the paper. Here it crosses the first beam, forming a pattern. When the film is developed and lit in the correct way, a 3D image can be seen.

Laser A device that creates an intense beam of light. The light waves in a laser beam all have the same wavelength and are all “in phase”: their crests and troughs line up. The word “laser” is short for Light Amplification by Stimulated Emission of Radiation. The atoms of the material inside a laser are “stimulated” by giving them light or electrical energy. This makes them emit an intense beam of light. Lasers are used to play and record music, to cut metal, perform surgery and carrying data along optical fibres.

Lasing material The substance inside a laser. This can be a solid, a liquid or a gas. The lasing material is contained in a tube with a mirror at one end and a half-silvered mirror at the other. Light bounces through the material, gaining strength to form an intense beam.

Loudspeaker A device that turns electric signals into sound waves. Most speakers consist of a coil of wire held between two magnets. An electric current creates a magnetic field in the wire, which is alternately attracted to or repelled by the magnets in rapid succession. The coil vibrates, moving a cone, which sends sound waves into the air.

Low-power laser A laser used to play CDs, read barcodes and send fibre-optic signals. Low-power lasers are normally red lasers that use semiconductor materials.

Maiman, Theodore (1923–2007) American physicist who built the first working laser in 1960. Maiman's laser used a ruby crystal as its lasing material.

Microphone An electronic device that turns sound waves into electric signals. In a condenser microphone, electricity flows between two metal plates. When sound waves vibrate the outer plate, the electric field between the plates changes, creating an electric signal. In a dynamic microphone, sound waves vibrate a wire coiled around a magnet, creating an electrical signal in the wire.

MP3 A type of digital audio file widely used to store compressed music files. Compressed files take up much less memory than the original sound file, but result in some loss of quality. However, by compressing files, hundreds of thousands of songs can be stored on a computer, smartphone or portable media player.

Tape recording A way of recording sound on to a length of magnetic tape. An electrical signal from a microphone is sent to an electromagnet, which creates a pattern in the tiny magnetic particles that coat the tape. A tape player converts the magnetic pattern into an electric signal, which is amplified and sent to a speaker.

Consultant: Chris Oxlade