L'I.O.T.A. :
a 75 years young institute
by Gérard Roblin

Two years ago, the "Institut d'Optique théorique et appliquée" of Orsay
celebrated its 75 years existence.

During the first world war, from 1915, the need of optical devices is particularly obvious, and France lacks engineers to compute the different parts of them. Then, the creation of an institute of optics, intended to instrumental optics teaching, is considered and, en 1916, a project established by Henri Chrétien and the Duke de Gramont, is showed to Paul Painlevé, Minister of the Public Instruction Department, who persuades the Ministers of the Trade, the War and the Marine Deparments. An interministerial committee is created, managed by General Bourgeois, the head of the armies geographical service. The Institute of Optics could move into a Montparnasse boulevard building only after the end of the war, in 1919.

Its activities began in 1920.
Acknowledged as an institution of Public Utility by a law of august 10, 1920, this date is usually its birthdate. The Duke de Gramont managed the Institute board until his death in 1962 (his first successor was Alfred Kastler, Nobel Prize of physics) and Charles Fabry was the first Director of the Institute until 1945.
The aims of Institute of Optics were triple : teaching, research and results broadcasting.

Teaching

Teaching must train :

engineers specialized in optical science in the "Ecole Supérieure d'optique". They must be able to compute, project an install civil and military optical devices and laboratory instruments using optical properties.
skilled workers, in a professional school (begun later Fresnel public high school), to be able to make optical components entering into the conception of an instrument.

Research

Research by elaborating, in laboratory, projects, adjustments and controls of new instruments which can be transferred to industries.

Broadcasting

Broadcasting, by means of the "Revue d'Optique" Editions (begun later independent), which published in a monthly magazine the essential results of this discipline founded by I.O.T.A. researchers and national industry engineers and books including all optical knowledge as soon as it was introduced in the "Ecole Supérieure d'Optique" lectures.
Institute of Optics activities must greatly developped themselves during the last 75 years, as much in research as in teaching. Those two parts are divided with difficulty because they are made by the same people.

At the beginning, the task of the Laboratory is the one of a technical center helping manufacturers by control and expertise of their products. Research gradually began essential and grew under management of Charles Fabry and also under the one of Charles Devé after moving, in 1926, in a more spacious and better adapted building located on "boulevard Pasteur" in Paris.
The physical optics study grew and its properties are used in the instruments design.
The studies of homogeneity defects of the glasses and of their thermal treatment began with Aniuta Winter.
Research began in the infrared domain and André Bayle (who founded the REOSC) elaborates the first compensated photopiles and manufactures large dispersion spectrographs and spectrometers.
The instrument transmission is improved by the first optical coatings. The links between physiological optics and instrumental specifications are formulated by Albert Arnulf.

After the second world war, Pierre Fleury began Director of the Institute and Albert Arnulf managed the Laboratories. The physiological optics is improved and glasses study continued.
The double monochromators studied by Jean Terrien (who became BIPM Director) and François Desvignes equip several establishments.
André Maréchal formulated his rule and developped the notion of spatial frequencies, initiating their filtering with Madeleine Marquet and FTM measurement.
The observation of phase objects is improved by Maurice Françon and Georges Normarski just as the medical endoscopy by Jacques Vulmière.
The thin layers are studied by Florin Abeles and Paul Croce.
Original studies on flying spot microscope, first type of optical scanning microscope, began and Jean-Paul Marioge made seriously use of manufacturing techniques of aspherical surfaces previously studied before the war.

I.O.T.A. became a CNRS associated laboratory thanks to the quality of its researches in 1966.

The total number of students increasing and the development of research require a new establishment in Orsay in the same year, completed by a second part 10 years later. André Marechal succeeds Pierre Fleury.
Laser appears in Institute. Jacques Ducuing experiences non linear optics for the first time. The coherent optics develops with Serge Lowenthal so as the medical imagery.
The multiple thin layers with high reflectivity in the X-UV range are studied and manufactured.
Materials working techniques, notably their polishing, are improved and the department of metrology is approved by BNM. But this period opens a new way by the study of fundamental phenomena : evanescent waves, optical levitation, inertial effect of spin of the photon visualized by Christian Imbert and the non separability principle in quantum mechanics confirmed by Alain Aspect.
Now, under Christian Imbert management, the subjects of research at the Institute of Optics are atomic optics, non linear optics and photorefractivity, quantum optics, physics of thin layers, physics of images, optical surfaces and components, instrumentation and metrology.

Teaching takes advantage of these research developments. At the beginning (1920), the school essentialy recruits qualified engineers and french and stranger officers (land forces and navy), a few number of courses are dispensed :

Introduction to Optics by Charles Fabry,
Optical Instruments by Lucien Dunoyer,
Optical design by Henri Chrétien,
Physiological Optics by André Broca,
Physical Chemistry an chemistry of optical glasses by Nicolardot.
They are completed by some lectures on specific subjects given by Maurice de Broglie, Aimé Cotton, Mouton, Gustave Yvon.

The laboratory classes, which were in a few number at the opening of the school are particularly promoted, as also classes of glass working, when the institute was settled in its new building. One year is sufficient to have the degree of engineer after an examination containing the presentation of an optical instrument project. Later, fewer graduated students being recruited, new courses are required and to first (optical design teached successively after Chrétien by Jean Cojan, Jean Burcher, Pierre Givaudon, Roland Geyl ; physiological optics or geometrical optics teached during a long time respectively by Yves Legrand or Michel Cagnet) are added other subjects : machine-drawing, technology, mechanics, instruments design under the mastership of the Roux brothers, Lucien Nicolas, Lucien Reymond.

The duration of studies grows into two years in 1942, then three from 1952 and new courses are added : thin layers, image formation, introduction to spatial frequencies.
In 1959, the entrance examination is joined to this of the "Ecole Supérieure d'Electricité", later to this of the "Ecoles Centrales" of Paris and Lyon and in 1965 the school established in Orsay.
New teachings are given as electronic, optical fibers and integrated optics, computing, laser, quantum mechanics, optoelectronics, solid state physics, but also English and management. Education evolves to this of physicist engineers specialized in optics.
Today, if the curriculum of the students comprises a period of industrial probation possibly of long time, they can choose during the third year of studies between five options giving an idea on the aims of the school : optical systems, laser and non linear optics, image processing, optical telecommunication and optical sensors, management.
Because the groups of students graduating each year were progressively increasing from some units to about fifty, more of sixteen hundred have been graduated at the "Ecole".
It is not possible to name all these people, but, in addition of those who are mentionned before, we can mention in chronological order some of them, sometimes forgotten.

In industry we cannot forget :

Maxime Stiassnie famed in microscopy,
André Nectoux and its refractometer,
Pierre Angenieux and its zoom,
Serge Clavé and its machines,
Jean Blasse author of the "bloscop",
Raymond Dudragne who develops ophtalmological instrumentation,
Roger Bel head of MTO and past president of the GIFO,
André Benoit well known,
André Mirau and its inferometer,
Edgar Hugues (CERCO),
Bernard Maitenaz author of the "Varilux",
Pierre Tournois appointed by Thomson,
Jean-Pierre Laude and Gilbert Hayat (Instruments SA),
Dominique Ruffi de Ponteves (SFIM),
Gilles Brassart who founded BMI and the younger managers
Patrick Lafond and Jacques Delacour. Activities of fellows of the school are known in different domains of research : the astronomers Maurice Paul,
André Baranne and Antoine Labeyrie, the general engineers
Bernard Cuny and Marcel Déramond,
Félicien Blottiau pioneer in the field of colorimetry,
Georges Stroke master to engrave the gratings,
André Girard author of the grid spectrometer,
Alain Carenco and Serge Valette in field of integrated optics,
François Salin and the propagation of the "soliton".
The "Revue d'Optique théorique et instrumentale" has been during a long time managed by Emile Perrin, number of technicians working in industry and laboratories have been schooled by Charles Savigny.
To end, we will citate one painting master,
Charles Lapicque, who became engineer to understand the phenomen of color vision.

Gérard ROBLIN