From the Luminiferous Ether to the Boeing 757: A History of the Laser Gyroscope

Abstract

From the Luminiferous Ether to the Boeing 757: A History of the Laser Gyroscope DONALD MACKENZIE Inertial navigation systems are central to modern navigation. They permit wholly self-contained navigation of remarkable accuracy. They are now standard in long-range civil aircraft and most modern military aircraft, as well as in ballistic missiles, cruise missiles, space boosters, and submarines. They are increasingly to be found in shorter-range tactical missiles, land vehicles such as tanks or selfpropelled artillery, and some surveying applications. At the heart of inertial navigation are the inertial sensors them­ selves: gyroscopes, which sense rotation, and accelerometers, which measure acceleration. During the last twenty years, the former have undergone what those involved see as a technological revolution. Since the beginnings of inertial navigation in the 1930s, the gyro­ scopes used had remained analogs—however sophisticated—of the child’s spinning toy, reliant in their detection of rotation on the mechanics of a rapidly revolving rotor. But they have now been challenged by inertial sensors in which the detection of rotation is achieved by optical, rather than mechanical, means: laser gyroscopes. All the major corporate suppliers of inertial technology, bar one, are heavily committed to laser gyroscope technology. A basic shift has thus taken place in this key modern technology. This article begins with the conceptual origins of the laser gyro­ scope, which are remote from the “high-tech” world of the modern Dr. Mackenzie holds a personal chair in sociology at the University of Edinburgh. He is the author of Inventing Accuracy: A Historical Sociology of Nuclear Missile Guidance (Cambridge, Mass., 1990). The interviews drawn on here were made possible by a grant from the Nuffield Foundation on “The Development of Strategic Missile Guidance Technology” (SOC442). Their further analysis was part of work supported by the Economic and Social Research Council under the Programme on Information and Communication Technologies (A35253006) and Science Policy Support Group Pro­ gramme of Science Policy Research in the Field of Defence Science and Technology (Y307253006). The author thanks all those who commented on earlier drafts of this article and is grateful to Dr. Wolfgang Riidig for assistance in the research.© 1993 by the Society for the History of Technology. All rights reserved. 0040-165X/93/3403-0003$01.00 475 476 Donald MacKenzie device. They lie in experiments probing the controversial question of the existence of the ether, the massless substance that pre-Einsteinian physics took to be the medium of the transmission of light. In particular, French physicist Georges Sagnac (1869-1928) believed that his work on the optical detection of rotation refuted Einstein. The second part of the article describes the move of what became known as the “Sagnac effect” from science to technology, a move that took place between 1959 and 1963. The invention of the laser was fundamental to this move, but more was involved thanjust a new light source. As quantum electronics flowered, the optical detection of rotation was reconceptualized. On January 7, 1963, a prototype laser gyroscope first detected rotation, and that date can be taken as indicating the end of the process of “inventing” the laser gyroscope and the beginning of the “development” phase of the device’s history. That development phase is the subject of the third part of the article. It stretched from 1963 to the first unequivocally successful tests of a practical laser gyro in 1975 and proved as crucial and as troublesome in the case of the laser gyro as elsewhere in the history of technology.1 The fourth part describes the growing acceptance of the laser gyro after 1975. It highlights the single most crucial event in that process of acceptance: the decision to adopt the new device as the core of the standard navigation and attitude reference system for the new civil air transports, the Boeing 757 and 767. The article ends with a discussion of what can be learned from this episode about the nature of technological change. The history of the laser gyroscope underlines the significance of the fusion of scientific and technological concerns in the new specialism of quantum elec­ tronics. It supports those who have noted the pervasiveness of military involvement in quantum electronics, while...