Table of contents

Short access time and compact realisation of data storage and display devices no longer belong tobl a. oddities and will soon have many applications.

This paper deals with PHEDRE and SEMIRAMIS, two solutions given to the problems of information storage.

We first describe the data storage mean:

• Data (typically prints or pictures) is modulated by a reference beam and recorded by superimposition on small areas of photographic films or plates;

• Secondly, recording and retrieval procedures will be detailed.

The design, construction, and performance of a high resolution monochromator are described: optical path, choice of each component, mechanical construction specially the system which rotates the grating in linear cm^-1. A resolution of. 5 cm^-1 is obtained. We indicate the variation of the resolution R of the instrument in fonction of the slitwidths and also some examples of high resolution in Raman's diffusion with the spectrometer which is built with this monochromator.

An apodization scheme for increasing the Sparrow resolution limit under the partially coherent illumination is formulated via the calculus of variations. The required pupil functionsa re obtained by solving an homogeneous Fredholm integral equation and evaluated as functions of the coherence condition of illumination and the total light flux passing through the aperture.

A new method of obtaining aspherical surfaces from elasticity is applied to the wave-front function. The primary aberrations with arbitrary amplitude are considered in detail. It is shown with respect to conventional criteria concerning a given value of the normalized intensity at the diffraction focus, that three simple loads and associate thickness configurations of the plates can be found in the case of primary spherical aberration. One configuration for simple loads and thickness is found in each case for primary coma and primary astigmatism.

In this paper, we present a review of the ultraviolet molecular Nitrogen lasers from their origin until 1974, these lasers being considered as the representative of UV lasers with pulsed electronic pumping and low pressure molecular gases. Principaly, are developped: the laser spectroscopy, the inversion conditions, a valuation of the power density and maximum efficiency, the amplification and oscillation conditions. So, the performances of different technologies are compared and analyzed.