A light spark of intellect

Mario Bertolotti is a senior professor at Rome's La Sapienza University and a prominent figure in European laser research. The present work is a translation of his Storia del Laser published in 1999.

This rather scholarly work - much more than a mere history of the laser - sets out to cover a huge canvas. The origins of the science of optics, Newtonian mechanics, the wave theory of light, statistical mechanics, the old quantum theory, quantum mechanics, atomic physics and spectroscopy are all traced via detailed accounts of the life histories of the main protagonists. The prehistory of the laser, so to speak, comprises the first nine of the 14 chapters. The dawn of the laser idea is reached only in chapter ten with a description of the 1954 demonstration by Charles Townes and his group at Columbia University of a working microwave amplifier employing stimulated emission of radiation - the maser.

In 1958, with his brother-in-law Arthur Schawlow (a researcher at Bell Labs), Townes published a paper indicating how the concept could be extended to the infrared and optical regime. Meanwhile, Gordon Gould (then a graduate student at Columbia) had independently come up with many of the same ideas in late 1957 and had his notebook notarised so that he could apply for a patent. Gould persuaded the management of a small research company to submit a research proposal for military funding, only to find himself barred from working on the resulting classified project because of his youthful flirtation with communism. To cap it all, the race to demonstrate the first working optical maser (or laser, to use Gould's acronym for light amplifier using stimulated emission of radiation) was won by Theodore Maiman of Hughes Research Laboratories in May 1960.

Bertolotti focuses on biographical aspects rather than on attacking the hard science head on, so he largely eschews mathematical formulae. An example of this is the illustration of the rate processes by which a population inversion is achieved among the energy levels of an atomic system in terms of the number of monkeys occupying branches in a tree at varying heights above ground level. But, despite the author's attempt to explain some of the concepts in terms understandable to the non-specialist, space constraints compel him to gloss over the complexities of many of the more difficult areas. It is therefore not easy to discern what the target readership might be. I suspect the lay reader may be somewhat challenged.

If the author's intention was to provide the historical background and a description of the personalities who contributed to the invention of the laser, he has succeeded well. Bertolotti's narrative charts the evolution of ideas leading up to the laser and the important contributions of less well-known researchers such as Tolman, Ladenburg and Fabrikant, as well as those of the big guns such as Einstein, Planck and Townes. There are a few oddities - the spelling "Schawlow" as "Shawlow" and a few mistakes in figures and captions. Despite such minor irritations, readers familiar with the underlying science will find the glimpses into the lives of the hundred or more personalities truly fascinating. The book also contains a fine gallery of photographs of the scientists whose work contributed to the history and prehistory of the laser.

Colin Webb was formerly head of atomic and laser physics, Oxford University, and is chairman, Oxford Lasers.