Matra

About: Matra is a based out in . It is known for research contribution in the topics: Signal & Detector. The organization has 1330 authors who have published 1216 publications receiving 17967 citations.

Polarizers at 1.053 um deposited on silica substrate for high laser flux applications in a vacuum

Abstract: The French Megajoule Project requires polarizers with high laser-induced damage thresholds. Such polarizers must be deposited on silica substrates, which are commonly prone to stress leading to early failure. Better stress control in the films require an optimization of the stack design as well as the deposition parameters. The thermal e-beam technique is used. We present the spectral behavior of such 1.03 micrometers polarizers in air and under vacuum at the Brewster incidence angle of 55 degrees 4 along with the damage test results.

New development of a long linear array for 11.3- to 12.3-um Earth observation

Abstract: In the frame of technological preparation for scientific Earth observation programs, the European Space Agency (ESA) has undertaken breadboarding activities dedicated to high resolution thermal radiometer to be implemented on a Low Earth Orbit satellite. Based on the lessons learned during the previous breadboarding phase and taken into account the modification of instrument concept, a LWIR linear focal plane breadboard has been studied and developed for the 11.3 to 12.3 micrometer range. The breadboard is made of two 256 pixels 30 micrometer pitch HgCdTe modules mechanically butted and indirectly hybridized to four multiplexers. Due to image rotation at focal plane level, a linear topology has been selected for pixel arrangement. To achieve the required 0.1 K NEdT, the detector is operated at 55 K. The detector breadboard manufactured and pre characterized by LETI/LIR and SOFRADIR has been integrated in a dedicated test set-up at MMS. First results of the characterization will be presented, with particular emphasis about the dark current and its dispersion as a function of temperature, and the low frequency noise measurements.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Addition device for feeding bulk material into a liquid stream

Abstract: For an addition device having a housing (1) for feeding pulverulent or granular bulk material from a storage hopper (7) into a water stream which flows through a housing duct (8), to achieve a uniform mixing with a presettable mixing ratio even with a varying water flow rate, it is proposed to transport the bulk material by motor-driven star wheel feeders (5) and to seal off the star feeder wheel chamber (13) from the feed space and the water space (8) with a metal-to-metal joint by a sleeve (3) formed in the manner of a water tap spigot.

Polygon subdomain basis-function model for the ring element in FSS arrays

Abstract: An efficient subdomain approach is presented which can predict the frequency response of ring-element frequency-selective surfaces (FSS) more accurately than existing entire-domain models. The integral equation for the unknown fields (or currents) on the frequency-selective surface is used for the mathematical model, and the elements are approximated by two mutually rotated polygons. Roof-top basis functions are used on each polygon chord to represent the unknown fields (or currents). This method offers a significant improvement in computational efficiency when compared with other subdomain methods that have been reported. This is achieved by using far fewer subsections, thus reducing the number of unknowns to be determined. Numerical results for several FSS geometries are compared with those obtained using the entire-domain model and measurements, to demonstrate that this technique offers high reliability as a design tool, particularly for single-screen FSS structures.