LISA LISA Three spacecrafts 2.5 10 9 m arms Laser Interferometry - PowerPoint PPT Presentation

Ester Abram AN INTRODUCTION TO ITS POINTING DIFFICULTIES Master Student Supervisors: Ernst-Jan Buis (TNO) Niels van Bakel (Nikhef) LISA

LISA • Three spacecrafts • ≈ 2.5 10 9 m arms • Laser Interferometry • No seismic noise 3/13/2019 R&D Plenary Meeting - Ester Abram 2

Orbit 3/13/2019 R&D Plenary Meeting - Ester Abram 3

Orbit • Equilateral triangle • Constant arm length • Tidal forces • Inclination No “constant” triangle 3/13/2019 R&D Plenary Meeting - Ester Abram 4

Pointing • Six laser links • Pointing • Tilt • Offset • FOV How to? 3/13/2019 R&D Plenary Meeting - Ester Abram 5

Content • Breathing angle • Point ahead angle • How to compensate • My work 3/13/2019 R&D Plenary Meeting - Ester Abram 6

Breathing angle 3/13/2019 R&D Plenary Meeting - Ester Abram 7

Breathing angle 3/13/2019 R&D Plenary Meeting - Ester Abram 8

Breathing angle 3/13/2019 R&D Plenary Meeting - Ester Abram 9

Breathing angle Adjust telescopes • Optical Assembly Tracking Mechanism (OATM) 3/13/2019 R&D Plenary Meeting - Ester Abram 10

Breathing angle Adjust telescopes • Optical Assembly Tracking Mechanism (OATM) • Micronewton thrusters • Optical assembly 3/13/2019 R&D Plenary Meeting - Ester Abram 11

Breathing angle Adjust telescopes • Optical Assembly Tracking Mechanism (OATM) • Micronewton thrusters • Optical assembly Otherwise outside FOV (= 8 𝜈𝑠𝑏𝑒 ) 3/13/2019 R&D Plenary Meeting - Ester Abram 12

Six Laser Links 3/13/2019 R&D Plenary Meeting - Ester Abram 13

Six Laser Links • Time delay 3/13/2019 R&D Plenary Meeting - Ester Abram 14

Laser Link Varying arm lengths and angles: • Signal • Pointing 3/13/2019 R&D Plenary Meeting - Ester Abram 15

Laser Link Varying arm lengths and angles: • Signal • Pointing  Point Ahead Angle (PAA) Otherwise you will ‘miss’ 3/13/2019 R&D Plenary Meeting - Ester Abram 16

Point Ahead Angle (PAA) Due to relative velocity: • “Inplane” and “Outplane” PAA 3/13/2019 R&D Plenary Meeting - Ester Abram 17

Point Ahead Angle (PAA) Due to relative velocity: • “Inplane” PAA • Telescope • “Outplane” PAA • PAAM 3/13/2019 R&D Plenary Meeting - Ester Abram 18

PAA Outplane • Point ahead angle mechanism (PAAM) • Two piezo stacks • Dynamic control • High precision 3/13/2019 R&D Plenary Meeting - Ester Abram 19

PAA Outplane • Point ahead angle mechanism (PAAM) • Two piezo stacks • Dynamic control • High precision The PAAM will send the transmitted beam under an angle with the received beam 3/13/2019 R&D Plenary Meeting - Ester Abram 20

PAA Inplane Control telescopes: 3/13/2019 R&D Plenary Meeting - Ester Abram 21

PAA Inplane Control telescope: • It will receive the incoming beam ‘straight’ 3/13/2019 R&D Plenary Meeting - Ester Abram 22

PAA Inplane Control telescope: • It will receive the incoming beam ‘straight’ • Affects outgoing beam • Not dynamic control • Heavy (noise) 3/13/2019 R&D Plenary Meeting - Ester Abram 23

My work Find a/the best way to point • Different strategies: ‘Center’ : ‘Wavefront ’: Receive the Aim for the center incoming beam of the telescope straight 3/13/2019 R&D Plenary Meeting - Ester Abram 24

‘Center’ ‘Wavefront’ 3/13/2019 R&D Plenary Meeting - Ester Abram 25

Angle (rad) Angle (rad) ‘Center’ ‘Wavefront’ 3/13/2019 R&D Plenary Meeting - Ester Abram 26

My work Find a/the best way to point • Different strategies: • ‘Center’ • ‘Wavefront’ • Different methods: • ‘No control’ • ‘Full control’ • ‘Step and stare’ (SS) 3/13/2019 R&D Plenary Meeting - Ester Abram 27

My work - Goal • Good and fast simulation and calculations • Reliable • Optimized pointing • How to control the PAAM • How to control the telescope • Add additional inplane PAAM? 3/13/2019 R&D Plenary Meeting - Ester Abram 28

Sources • http://www.astronomy.com/news/2018/11/looking-ahead-to-the- lisa-gravitational-wave-detector • https://www.researchgate.net/figure/Realization-of-the-Point-Ahead- Angle-Mechanism-The-mirror-is-glued-to-a- monolithical_fig4_321192271 3/13/2019 R&D Plenary Meeting - Ester Abram 29