LISA's Lasers and Optics (2/2) 
LISA's Lasers and Optics (2/2)
by Caltech / Kip Thorne
Video Lecture 63 of 69
Copyright Information: This video is taken from a 2002 Caltech on-line course on "Gravitational Waves", organized and designed by Kip S. Thorne, Mihai Bondarescu and Yanbei Chen. The full course, including this and many other lecture videos, exercises, solutions to exercises, and lists of relevant reading, are available on the web at http://elmer.caltech.edu/ph237/
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Date Added: July 22, 2010

Lecture Description

LISA's Lasers and Optics - Week 17, Lecture 32  [by Robert Spero (JPL)]

  1. Introduction: Comparison and contrast of LISA and LIGO
  2. LISA's light beams: 
  1. parameters; spreading (far-field limit), 
  2. why must receive, photodetect and transmit new beam back ("transpond" the light) rather than reflecting off a mirror

Detection of incoming beam: 

  1. shot noise prevents simple photodetection 
  2. reduce shot noise by beating incoming beam against local oscillator light
  3. modulation & demodulation of local oscillator light to reduce noise
  4. possible designs for transponding system: DC lock, frequency offset lock, and offset-cancelled lock (current preference)

Three-spacecraft phase-monitoring system (current baseline design):

  1. 1 master laser, three slave lasers, 4 phase measurements; 3 semi-independent 2-arm interferometers
  2. Time-delay interferometry [TDI] as an attractive alternative

Laser frequency noise and its control

  1. Analysis when GW wavelength is long compared to spacecraft separation [for pedagogical simplicity]; suppression of laser noise by near equality of arm lengths
  2. Problem of influence of round trip time delay on laser frequency control
  3. Laboratory experiments on laser frequency stability

Time-delay interferometry [TDI] as a way to remove laser frequency noise

  1. TDI as a transponder-free scheme: all lasers are free running
  2. Phase-meter for monitoring phase difference between incoming beam and local laser
  3. Combine phase differences with appropriate time delays to cancel laser frequency noise
  4. Uncertainty in (time-varying) arm lengths produces error in cancellation; demonstration that 30 meter accuracy in arm-length knowledge is adequate
  5. Details of how phase meter works
  6. Measurement of arm lengths to 30 meter accuracy

Noise due to fluctuations in pointing of laser beams

Course Index

  1. The Nature of Gravitational Waves
  2. Gravitational Waves Data Analysis
  3. Gravitational Wave Sources in Neutron Stars
  4. Introduction to General Relativity: Tidal Gravity
  5. Mathematics of General Relativity: Tensor Algebra
  6. Mathematics of General Relativity: Tensor Differentiation
  7. Introduction to General Relativity (4/5)
  8. Introduction to General Relativity (5/5)
  9. Weak Gravitational Waves in Flat Spacetime (1/6)
  10. Weak Gravitational Waves in Flat Spacetime (2/6)
  11. Weak Gravitational Waves in Flat Spacetime (3/6)
  12. Weak Gravitational Waves in Flat Spacetime (4/6)
  13. Weak Gravitational Waves in Flat Spacetime (5/6)
  14. Weak Gravitational Waves in Flat Spacetime (6/6); Propagation of Gravitational Waves Through Curved Spacetime (1/5)
  15. Propagation of Gravitational Waves Through Curved Spacetime (2/5)
  16. Propagation of Gravitational Waves Through Curved Spacetime (3/5)
  17. Propagation of Gravitational Waves Through Curved Spacetime (4/5)
  18. Propagation of Gravitational Waves Through Curved Spacetime (5/5)
  19. Generation of Gravitational Waves by Slow-Motion Sources in Curved Spacetime (1/2)
  20. Generation of Gravitational Waves by Slow-Motion Sources in Curved Spacetime (2/2)
  21. Astrophysical Phenomenology of Binary-Star GW Sources (1/5)
  22. Astrophysical Phenomenology of Binary-Star GW Sources (2/5)
  23. Astrophysical Phenomenology of Binary-Star GW Sources (3/5)
  24. Astrophysical Phenomenology of Binary-Star GW Sources (4/5)
  25. Astrophysical Phenomenology of Binary-Star GW Sources (5/5); Post-Newtonian G-Waveforms for LIGO & Its Partners (1/2
  26. Post-Newtonian Gravitational Waveforms for LIGO & Its Partners (2/2)
  27. Supermassive Black Holes and their Gravitational Waves (1/3)
  28. Supermassive Black Holes and their Gravitational Waves (2/3)
  29. Supermassive Black Holes and their Gravitational Waves (3/3); Gravitational Waves from Inflation (1/2)
  30. Gravitational Waves from Inflation (2/2)
  31. Gravitational Waves from Neutron-Star Rotation and Pulsation (1/2)
  32. Gravitational Waves from Neutron-Star Rotation and Pulsation (2/2)
  33. Numerical Relativity as a Tool for Computing GW Generation (1/2)
  34. Numerical Relativity as a Tool for Computing GW Generation (2/2)
  35. The Physics Underlying Earth-Based Gravitational Wave Interferometers (1/4)
  36. The Physics Underlying Earth-Based Gravitational Wave Interferometers (2/4)
  37. The Physics Underlying Earth-Based Gravitational Wave Interferometers (3/4)
  38. The Physics Underlying Earth-Based Gravitational Wave Interferometers (4/4)
  39. Overview of Real LIGO Interferometers (1/2)
  40. Overview of Real LIGO Interferometers (2/2)
  41. Thermal Noise in LIGO Interferometers and its Control (1/2)
  42. Thermal Noise in LIGO Interferometers and its Control (2/2)
  43. Control Systems and Laser Frequency Stabilization (1/2)
  44. Control Systems and Laser Frequency Stabilization (2/2)
  45. Interferometer Simulations and Lock Acquisition in LIGO
  46. Seismic Isolation in Earth-Based Interferometers
  47. Quantum Optical noise in GW Interferometers (1/2)
  48. Quantum Optical noise in GW Interferometers (2/2)
  49. LIGO data analysis (1/2)
  50. LIGO data analysis (2/2)
  51. The Long-Term Future of LIGO: Facility Limits
  52. The Long-Term Future of LIGO: Techniques for Improving on LIGO-II
  53. Large Experimental Science and LIGO as an Example (1/2)
  54. Large Experimental Science and LIGO as an Example (2/2)
  55. Resonant-Mass GW Detectors for the HF Band (1/2)
  56. Resonant-Mass GW Detectors for the HF Band (2/2)
  57. CAJAGWR talk by W.O. Hamilton on Resonant-Mass GW Detectors
  58. Doppler tracking of spacecraft for GW detection in the low frequency band
  59. Pulsar timing for GW detection in the very low frequency band
  60. LISA (Laser Interferometer Space Antenna) for GW Detection in LF Band: Conceptual Design (1/2)
  61. LISA (Laser Interferometer Space Antenna) for GW Detection in LF Band: Conceptual Design (2/2)
  62. LISA's Lasers and Optics (1/2)
  63. LISA's Lasers and Optics (2/2)
  64. Time-Delay Interferometry [TDI] for LISA (1/2)
  65. Time-Delay Interferometry [TDI] for LISA (2/2)
  66. LISA's Distrubance Reduction System (DRS) [Drag-Free System] (1/2)
  67. LISA's Distrubance Reduction System (DRS) [Drag-Free System] (2/2)
  68. The Big-Bang Observatory [BBO]: A Possible Follow-On Mission to LISA
  69. GW's from Inflation and GW Detection in ELF Band via Anisotropy of CMB Polarization

Course Description

Caltech's Physics 237-2002: Gravitational Waves
A Web-Based Course organized and Designed by Kip S. Thorne, Mihai Bondarescu and Yanbei Chen.

This course contains all the materials from a graduate-student-level course on Gravitational Waves taught at the California Institute of Technology, January through May of 2002. The materials include Quicktime videos of the lectures, lists of suggested and supplementary reading, copies of some of the readings, many exercises, and solutions to all exercises. The video files are so large that it may not be possible to stream them from most sites, but they can be downloaded. Alternatively, the course materials on DVD's can be borrowed via Interlibrary Loan from the Caltech Library (click on CLAS, then on Call Number, then enter QC179.T56 2002 ).

Questions and issues about this course and website can be directed to Mihai Bondarescu or Yanbei Chen.

Resources:

Credits:
Lectures by Thorne and Guest Lecturers*
Video of lectures by Bondarescu and Chen
Homework problems by Thorne and Guest Lecturers
Homework solutions by Bondarescu and Chen

*John Armstrong (JPL), Barry Barish, Erik Black, Alessandra Buonanno, Yanbei Chen, Riccardo De Salvo, Ronald Drever, Matt Evans, William Folkner (JPL), William Hamilton (LSU), Mark Kamionkowski, Albert Lazzarini, Lee Lindblom, Sterl Phinney, Mark Scheel, Bonny Schumaker (JPL), Robert Spero (JPL), Alan Weinstein, Phil Willems.

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