thermal compensation review
Skip this Video
Download Presentation
Thermal Compensation Review

Loading in 2 Seconds...

play fullscreen
1 / 16

Thermal Compensation Review - PowerPoint PPT Presentation

  • Uploaded on

Thermal Compensation Review. David Ottaway LIGO Laboratory MIT. Overview. Overview of Problem Road map for design choices (Set by other systems) Summary of current results from subscale tests and modeling Current known unresolved issues Plans and resources required for next year.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Thermal Compensation Review' - emi-boyer

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
thermal compensation review

Thermal Compensation Review

David Ottaway

LIGO Laboratory


  • Overview of Problem
  • Road map for design choices (Set by other systems)
  • Summary of current results from subscale tests and modeling
  • Current known unresolved issues
  • Plans and resources required for next year

Advanced LIGO Technical Review

thermal distortion
Thermal Distortion
  • Absorption in coatings and substrates => Temperature Gradients
  • Temperature Gradients => Optical path distortions
  • 3 Types of distortions, relative strengths of which are shown below:

Advanced LIGO Technical Review

thermal comparison of advanced ligo to ligo 1
Thermal Comparison of Advanced LIGO to LIGO 1

Advanced LIGO Technical Review

effect on advanced ligo interferometers
Effect on Advanced LIGO Interferometers

Advanced LIGO Technical Review

adaptive thermal compensation
Adaptive Thermal Compensation
  • Compensate for distortions in the substrates
  • Essential for Advanced LIGO sensitivity to be realized
  • Two parts to thermal compensation:

1. Coarse compensation of thermal lensing

using heating ring and shielding

2. Small scale compensation using scanning

CO2 laser

  • Accurate measurement of sapphire and fused silica thermal mechanical properties enable accurate models
  • Good propagation models to set design requirements (Melody and FFT Code)

Advanced LIGO Technical Review

requirements that flow from other systems
Requirements that flow from other systems
  • Core Optics (Down select)


-Significant possible inhomogeneous absorption

-> Small spatial scale correction (scanning laser)

-Large thermal conductivity

-> Small amount of coarse compensation (ring heater) on compensation plates

Fused Silica

-Poor thermal conductivity and homogenous absorption (ring heater)

  • DC or RF read out scheme (Down select)

-Reduces dependence on sidebands, might affect design requirements

  • Wavefront Sensing (LIGO 1 experience, not fully understood)

-High spatial quality sidebands are probably necessary for accurate alignment control, may negate the effect of read out scheme

Advanced LIGO Technical Review

summary of subscale experiments and modeling
Summary of Subscale Experiments and Modeling
  • Accurate measurements of fused silica and sapphire material properties
  • Experimental demonstration of shielded heater ring coarse spatial correction
  • Experimental demonstration of scanning CO2 laser fine spatial scale correction
  • Accurate models of Advanced LIGO Interferometers style interferometer using Melody and finite element analysis (Femlab), (Thermal modeling without SRM)
  • Scaling from subscale to full scale understood
  • Work done by Ryan Lawrence

Advanced LIGO Technical Review

heater ring thermal compensation
Heater Ring Thermal Compensation

Advanced LIGO Technical Review

sub scale scanning laser test
Sub Scale Scanning Laser Test

Advanced LIGO Technical Review

scanning laser test result
Scanning Laser Test Result

Uncorrected Optic (6712 ppm scatter from TEM00) Corrected Optic (789 ppm scattered from TEM00)

Advanced LIGO Technical Review

current known unresolved issues
Current Known Unresolved Issues
  • Gravitational wave sideband distortion and its effect on sensitivity. Generated within the cavity no distortion nulling due to prompt reflection. Greater understanding through incorporation in Melody (Ray Beausoleil)
  • Fabry-Perot mode size change due to input test mass surface deformation => Spot size change (actuate on arm cavity faces)
  • Accurate 2D absorption maps of Sapphire to aid in actuator selection (negative or positive dN/dT actuator plates)

Advanced LIGO Technical Review

plans and resources for next year
Plans and Resources for Next Year


  • Work with the Gin Gin Facility to determine prototype
  • Further modeling
  • Design requirements (29th Oct 2002)
  • Preliminary design (14th Apr 2003)


  • Staffing: Mason (1/5 time), Ottaway (1/4 time)
  • Ryan Lawrence graduating and leaving LIGO
  • Resources: $50 K in MIT LIGO budget to build prototype

Advanced LIGO Technical Review