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Photography by Matthias Zepper, source: Wikimedia Commons
Fifty years ago, on May 16, the first functioning laser was switched on at the Hughes Research Laboratories in California. Constructed by engineer and physicist Theodore
Maiman, this first Light Amplification by Stimulated Emission of Radiation device used a pink synthetic ruby rod to generate its powerful beam of light. Einstein proposed the idea of stimulated emission (in which a photon, or light particle, causes an excited atom to emit an identical photon) in 1917, but it was not until 1953 that American physicist Charles Townes was able to create the first ‘stimulated emission’ device, the “maser” – Microwave Amplification by Stimulated Emission of Radiation – in which microwaves were used as the atom-exciter. Townes and others then conceived of the idea of using visible light instead of microwaves and Maiman became the first to make the concept work.
However, other research teams were also working on the development of lasers and only a few months after Maiman’s first laser, a helium neon laser was in operation at the rival Bell Laboratories. By 1962 the gallium arsenide diode laser had been developed, which was the direct precursor of the small commercial laser devices widely used today.
Laser-based technologies have helped transform the world over the past fifty years, often in ways that are not readily apparent. Lasers can be found in supermarket bar-code scanners and hospital operating rooms; in DVD and CD players and the adaptive optics of telescopes; they create holograms and light shows and are widely used in industry for precision cutting and welding; lasers guide weapons to their targets and measure the exact distance to the Moon. Perhaps most important of all in today’s world, lasers make the internet possible, by carrying immense quantities of data along the fibre optic cables that network the globe.
Collection: Powerhouse Museum
An interesting laser-based device in the museum’s collection is this laser cielometer, an instrument used by meteorological and airport authorities worldwide to accurately determine the height of the cloud base (the lowest altitude of the visible part of a cloud mass). Cloud base is an important meteorological variable for aviation safety, as it determines whether pilots can use Visual Flight Rules or must follow Instrument Flight Rules for take-off and landing. A laser ceilometer determines the height of the base of the clouds by measuring the time required for a pulse of light to be scattered back from the cloud base.
Collection: Powerhouse Museum
The first laser ceilometer was developed in the mid 1960s and the instrument has become widely used in automated weather stations and at airports. The ceilometer in our collection was manufactured in the United States by Qualimetrics Inc. and installed at Armidale (NSW) airport where it operated between 1992-2000, before being replaced by a more advanced model. It was designed for permanent outdoor operation with its electronics hermetically sealed and protected from moisture by a replaceable desiccant cartridge.
