The Atmospheric LAser Doppler INstrument (ALADIN) is the payload of the ESA’s ADMAEOLUS mission, which aims at measuring wind profiles as required by the climatology and meteorology users. ALADIN belongs to a new class of Earth Observation payloads and will be the first European Lidar in space. The instrument comprises a diode-pumped high energy Nd:YAG laser and a direct detection receiver operating on aerosol and molecular backscatter signals in parallel. In addition to the Proto- Flight Model (PFM)., two instrument models are developed: a Pre-development Model (PDM) and an Opto-Structure-Thermal Model (OSTM). The flight instrument design and the industrial team has been finalised and the major equipment are now under development. This paper describes the instrument design and performance as well as the development and verification approach. The main results obtained during the PDM programme are also reported. The ALADIN instrument is developed under prime contractorship from EADS Astrium SAS with a consortium of thirty European companies.
The ALADIN Instrument is a Doppler Wind Lidar aboard the ESA Core Explorer Aeolus Mission. The main purpose of
this payload is the measurement of tropospheric wind profiles on a global scale. The concept is based on a solid-state
Nd:YAG laser associated with a direct detection frequency receiver.
An optical structural and thermal model (OSTM) of the instrument has been developed to validate at an early stage of the
programme the stability of the instrument. In particular, the WFE and defocus stability of the 1.5 m diameter Silicon
Carbide Telescope is a critical issue regarding instrument performances. In order to test the WFE and defocus stability
under thermal vacuum, a dedicated sensor has been developed. This Sensor is based on the Shack Hartman principle.
The aim of the sensor is to measure the telescope primary mirror deformations in a confocal configuration by adapting a
set of small mirrors on the mirror surface. The challenge was to keep these mirrors stable to better than 0.1μm
decenter/0.1μrd rotation to allow unbiased monitoring of the WFE and defocus under thermal vacuum. Experimental
results show the high measurement sensitivity achieved by the Hartman optical sensor.
The ALADIN Instrument is a Doppler Wind Lidar, which will be launched in 2007 aboard the ESA Core Explorer Aeolus Mission. The main purpose of this payload is the measurement of tropospheric wind profiles on a global scale. The concept is based on a solid-state Nd:YAG laser associated with a direct detection frequency receiver. Astrium-SAS is prime contractor for the development of ALADIN. This program includes in particular the development of a Pre Development Model for the critical parts of the instrument. This paper describes the flight instrument design and reviews the achievements of the PDM activities: this will cover in particular the development status of the engineering models of the CCD detectors, front-end units and spectrometers.
The thermo-optic coefficient (delta) n divided by (delta) T of CaF<SUB>2</SUB>, ZnS and Ge single crystals have been measured in the infrared from 20 degrees C to 100 degrees C. The laser interferometric method employed allows a determination of (delta) n divided by (delta) T with an accuracy close to 10<SUP>-6</SUP>K<SUP>-1</SUP> in the case of nonabsorbing materials. For Ge the uncertainty is increased by a factor of 3 and is mainly due to its increasing absorption coefficient with temperature. The behavior of ZnS was examined at 1.06 micrometers and 10.6 micrometers laser radiations; CaF<SUB>2</SUB> and Ge were investigated respectively at 1.06 micrometers and 10.6 micrometers.