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AEOLUS STATUS

AEOLUS STATUS. Part 1: Design Overview. Outline of the presentation. Introduction to ALADIN Laser transmitter (TXA) specification Overview on the Laser optical design Overview on the Laser thermo-mechanical design. ALADIN Measurement Geometry.

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AEOLUS STATUS

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  1. AEOLUS STATUS Part 1: Design Overview Working Group on Space-based Lidar Winds

  2. Outline of the presentation • Introduction to ALADIN • Laser transmitter (TXA) specification • Overview on the Laser optical design • Overview on the Laser thermo-mechanical design Working Group on Space-based Lidar Winds

  3. ALADIN Measurement Geometry • Wind measured by Doppler shift of backscattered light • Single line-of-sight of horizontal wind (HLOS) • Sun-synchronous orbit • Random error: < 2 m/s • Zero wind bias < 0.4 m/s Working Group on Space-based Lidar Winds

  4. Doppler shift of backscattered light vs laser pulse Aerosols signal (Mie) predominant at low altitude (< 2kms) Molecules (Rayleigh) predominant at higher altitude (> 2 kms) ALADIN Measurement principle Working Group on Space-based Lidar Winds

  5. ALADIN Optical Functional Diagram RSP principle Working Group on Space-based Lidar Winds

  6. Receiver Equipments Detection Front-end Chopper T/R Optics Rayleigh Spectrometer Working Group on Space-based Lidar Winds

  7. ALADIN Instrument Overview Working Group on Space-based Lidar Winds

  8. Instrument Core Working Group on Space-based Lidar Winds

  9. The ALADIN laser Transmitter (TXA) Working Group on Space-based Lidar Winds

  10. The ALADIN Laser Transmitter (TXA) • The ALADIN Laser transmitter is a Nd:YAG Q-switched Master Oscillator Power Amplifier (MOPA), frequency tripled & Injection-seeded. • It operates in Continuous Mode with a PRF of 50 Hz • The injection-seeding principle is based on the Ramp-Hold-Fire Working Group on Space-based Lidar Winds

  11. The ALADIN TXA Functional Block Diagram Working Group on Space-based Lidar Winds

  12. Injection + Master Oscillator section Rod Polarizer Q-Switch 5 mJ IR energy 1 mm @ 1/e2 Working Group on Space-based Lidar Winds

  13. 2nd pass Output Energy 130 mJ Input Energy 5 mJ 3.4 mm @1/e2 3rd pass Output Energy 350 mJ (IR) 1st pass Output Energy ~50 mJ Amplification Section Working Group on Space-based Lidar Winds

  14. Harmonic section 200 mJ IR + VIS 150 mJ UV Energy 350 mJ IR Energy Working Group on Space-based Lidar Winds

  15. Laser Opto-Thermo-Mechanical Design description Working Group on Space-based Lidar Winds

  16. Reference Laser Head (RLH) • Based on two Non Planar Ring Oscillators (monolithic design ensures high stability) • The Reference Laser is stabilized to a low drift resonator • The beat signal between seeder laser and reference laser is processed by a digital PLL (frequency locking loop) • The seeder beam is injected in a monomode fiber connected to the PLH Working Group on Space-based Lidar Winds

  17. Power Laser Head (PLH) Optomechanical Layout Working Group on Space-based Lidar Winds

  18. Power Laser Head (UOB + LOB) Working Group on Space-based Lidar Winds

  19. Upper Optical Bench (UOB) of the PLH Working Group on Space-based Lidar Winds

  20. Master Oscillator (MO) Rod & RMax • Cavity length is folded by 4 mirrors mounted on an Invar plate • The output coupler, the cavity end mirror (on the rod) and the Invar plate are mounted on the UOB Invar plate The piezo-actuator holds the output coupler Working Group on Space-based Lidar Winds

  21. LD2 LD4 LD6 LD8 LD3 LD5 LD7 LD1 Pump unit (1) • Zig-Zag Nd:YAG slab Laser diode pumped in front of the beam TIR for efficient optical energy extraction • Slab TIR coating LIDT limited @ about 100 MW/cm2 • 1000 W Laser Diodes Stacked Array used @ derated power ( ~700 W) • Typical lifetime 5.109 shots Working Group on Space-based Lidar Winds

  22. Pump Unit (2) • The pump unit (PU) is made in copper • Conductively cooled unit ( with thermal filler to minimize air-vacuum transition effect) • Operated @ 50 Hz • About 200 W average Heat dissipation PU longitudinal cross section Working Group on Space-based Lidar Winds

  23. PUMP UNIT (3) Pre-Amp PU installed on the UOB Working Group on Space-based Lidar Winds

  24. Harmonic Generation • LBO crystals used for SHG (25mm) and THG (35mm) • Type I Phase Matching for SHG, Type II Phase Matching for THG • Heater controlled crystal temperature higher than 30oC Working Group on Space-based Lidar Winds

  25. UOB Power Laser Head (PLH) Working Group on Space-based Lidar Winds

  26. LOB Power Laser Head (PLH) Working Group on Space-based Lidar Winds

  27. Pump Laser Diodes operation The heat current will be adjusted according to the formula: to keep constant the distribution of absorbed pump energy in the Nd:YAG rod and slab (same heat dissipation @ laser diode => same emission wavelength) Working Group on Space-based Lidar Winds

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