Dr Drullinger of the US National Institute of Standards and Technology (NIST) using an infrared detector to 'see' the beam of an infrared laser. The laser is part of the new NIST-7 atomic clock, which promises to be the world's most accurate. The infrared laser is one of several lasers used in the clock. It is used to 'cool' ions of hydrogen so that they may be contained within an ion trap. Other, visible light, lasers may then be used to measure the oscillation of the ions. The oscillation count is the key to precise time measurement, allowing an accuracy of one billionth of a second per day (one second in three million years). NIST-7 will become operational in 1992.