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Lozi J.,French National Center for Space Studies | Lozi J.,ONERA | Lozi J.,University Paris Diderot | Cassaing F.,ONERA | And 15 more authors.
Proceedings of SPIE - The International Society for Optical Engineering

Stabilizing a nulling interferometer at a nanometric level is the key issue to obtain deep null depths. The PERSEE breadboard has been designed to study and optimize the operation of cophased nulling bench in the most realistic disturbing environment of a space mission. This presentation focuses on the current results of the PERSEE bench. In terms of metrology, we cophased at 0.33 nm rms for the piston and 60 mas rms for the tip/tilt. A Linear Quadratic Gaussian (LQG) control coupled with an unsupervised vibration identification allows us to maintain that level of correction, even with characteristic vibrations of nulling interferometry space missions. These performances, with an accurate design and alignment of the bench, currently lead to a polychromatic unpolarised null depth of 8.9 × 10-6 stabilized at 2.7 × 10-7 on the [1.65 - 2.45] μm spectral band (37% bandwidth). With those significant results, we give the first more general lessons we have already learned from this experiment, both at system and component levels for a future space mission. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). Source

Heays A.N.,Leiden University | Eidelsberg M.,University of Paris Descartes | Stark G.,Wellesley College | Lemaire J.L.,University of Paris Descartes | And 7 more authors.
Journal of Chemical Physics

We observe photoabsorption of the W(1) ← X(0) band in five carbon monoxide isotopologues with a vacuum-ultraviolet Fourier-transform spectrometer and a synchrotron radiation source. We deduce transition energies, integrated cross sections, and natural linewidths of the observed rotational transitions and find a perturbation affecting these. Following a deperturbation analysis of all five isotopologues, the perturbing state is assigned to the v = 0 level of a previously unobserved 1Π state predicted by ab initio calculations to occur with the correct symmetry and equilibrium internuclear distance. We label this new state E″ 1Π. Both of the interacting levels W(1) and E″(0) are predissociated, leading to dramatic interference effects in their corresponding linewidths. © 2014 AIP Publishing LLC. Source

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