COURDE , Clément

Improving the angular resolution of telescopes implies an increase of their size. Spacecrafts in formation flying are more and more investigated for future space telescope projects. Operation of such systems requires absolute distance measurement between two spacecrafts with an accuracy of few tens of microns. The absolute distance measurement...

When implementing a diluted telescope with large dimensions, one has to reach the equal path condition to the different segments of the primary mirror. In this work we suggest a way to implement a fast laser ranging method able to provide the error signal, using phase detection of the microwave modulation of a laser beam.

We present a simple two-mode telemetry procedure which eliminates cyclic errors, to allow accurate absolute distance measurements. We show that phase drifts and cyclic errors are suppressed using a fast polarization switch that exchanges the roles of the reference and measurement paths. Preliminary measurements obtained using this novel design...

A laser ranging method is described that uses the phase of an amplitude-modulated laser beam: the frequency of the modulation is permanently adjusted to maintain a constant dephasing, and the distance is deduced from its measurement. We show that phase drifts and cyclic errors are suppressed using a fast polarization switch that interchanges...

Nous présentons deux télémètres basés sur un faisceau laser modulé en amplitude à haute fréquence (HF). L'information de distance est extraite de la phase du faisceau renvoyé par la cible. Dans la première mise en oeuvre proposée, l'erreur cyclique associée à une diaphonie optique entre la voie de référence et la voie de mesure est absente,...

Absolute distance measurement with accuracy below the micron scale is important in astronomical optical interferometry. We present here an absolute laser rangefinder which relies on the detection of a two mode interference signal. We exploit the specific signature of the signal to extract both the interferometric and synthetic phase...

A novel laser ranging method is described that uses a two-mode laser source, and detection of the phase of the return beam. The design eliminates the cyclic error usually associated with phase measurements and provides unambiguous, absolute distance determination. Measurements of an 8m path are obtained at a beat frequency of 13 GHz. We analyse...

We present two different laser ranging systems under development, both based on the use of a high frequency modulated beam. The first range meter makes no use of interferometry: only the phase of the return beam is detected, in a way that rejects cyclic errors due to optical and electronic crosstalk. An Allan deviation slightly better than 10nm...

Some measurement schemes have been proposed and realized for the absolute measurement of long distances with an accuracy better than 10 nm. Published measurement setups use one or even two laser frequency combs. But significant engineering will be required to space qualify such a system. Simple methods, less technology-demanding would be...

Some measurement schemes have been proposed and realized for the absolute measurement of long distances with an accuracy better than 10 nm. Published measurement setups use one or even two laser frequency combs. But significant engineering will be required to space qualify such a system. Simple methods, less technology-demanding would be...

In October 2012, the Ge?oazur TF laboratory in OCA has been reorganized to improve signal distribution stability. In particular we have implemented a new time scale TA(OCA) based on H-maser T4Science. The H-maser frequency is steered with an HROG-10 microphase stepper. The correction applied is computed every day taking into account the...

In this poster we elaborate the use of raw navigation data (range and Doppler observations) from the Lunar Reconnaissance Orbiter (LRO) available on the Planetary Data System (PDS), in order to study the orbit of this probe using the orbit determination software (GINS) developed by the French space agency (CNES). The constraints that are...

We present a direct comparison between two different techniques for the relative calibration of time transfer between remote time scales when using the signals transmitted by the Global Positioning System (GPS). In the remote sites, the local measurements are driving either the computation of the hardware delays of the local GPS equipment with...

LLR in IR (1064nm) gives an improvement in the temporal and spatial distribution of observations. Estimates of the lunar core using IR data will be presented.

Abstract The Satellite Laser Ranging (SLR) station known as GRSM-7845 in the International Laser Ranging Service (ILRS) is hosted by the Observatoire de la Côte d'Azur (OCA) located in Caussols, France. Its reference point is the intersection of the telescope axes, which is supposed to be static. Measuring devices and a data processing chain...

In this work, we report recent progress on the design of all-fibered ultra-high repetition-rate pulse sources for telecommunication applications around 1550 nm. The sources are based on the non-linear compression of an initial beat-signal through a multiple four-wave mixing process taking place into an optical fiber. We experimentally...

In this paper, we report recent progress on the design of all-fibered ultra-high repetition-rate pulse sources for telecommunication applications around 1550 nm. Based on the nonlinear compression of an initial beat-signal in optical fibers through a multiple four-wave mixing process, we theoretically and experimentally demonstrate that this...

Three independent time transfer techniques are in use in Observatoire de la Côte d'Azur (OCA): GPS, TWSTFT and T2L2. In Autumn 2013, a GPS receiver relative calibration campaign has been carried out. The result of this campaign, primary intended to compare GPS with T2L2, have allowed the calibration of the TWSTFT link between OCA and OP. We...

International audience

International audience

International audience

We present the procedure we followed to design an artificial corner reflector (CR) at the Calern site of Côte d'Azur Observatory (France). Although still few in number, such reflectors are an integral part of the Global Geodetic Observing System (GGOS) infrastructure. They can be used as a stable radar target in SAR images to connect local...

International audience

Satellite laser ranging (SLR) stations in the International Laser Ranging Service (ILRS) global tracking network come in different shapes and sizes and were built by different institutions at different times using different technologies. In addition, those stations that have upgraded their systems and equipment are often operating a...

Abstract We report on observations of the extended environment of the bright Be star γ -Cas performed using intensity interferometry measurements within its H α emission line. These observations were performed using a modified version of the I2C intensity interferometry instrument installed onto the 1.54 m MéO optical metrology telescope and a...