Laser Interferometer Gravitational Wave Observatorywillems/Pickoffs_and... · Web viewSee ASC Optical Lever Design Requirement Document, LIGO-T950106-01-D Optical Alignment of COS

LASER INTERFEROMETER GRAVITATIONAL WAVE OBSERVATORY

LIGO Laboratory / LIGO Scientific Collaboration

LIGO-T000092-02-D ADVANCED LIGO 10/4/00

Auxiliary Optics Support SystemDesign Requirements Document, Vol. 3:

Pickoffs and Telescopes

Michael Smith, Michael Zucker, Ken Mason, Phil Willems

Distribution of this document:LIGO Science Collaboration

This is an internal working noteof the LIGO Project.

California Institute of TechnologyLIGO Project – MS 18-341200 E. California Blvd.

Pasadena, CA 91125Phone (626) 395-2129Fax (626) 304-9834

E-mail: [email protected]

Massachusetts Institute of TechnologyLIGO Project – NW17-161

175 Albany StCambridge, MA 02139Phone (617) 253-4824Fax (617) 253-7014

E-mail: [email protected]

LIGO Hanford ObservatoryP.O. Box 1970

Mail Stop S9-02Richland, WA 99352Phone 509-372-8106Fax 509-372-8137

LIGO Livingston ObservatoryP.O. Box 940

Livingston, LA 70754Phone 225-686-3100Fax 225-686-7189

http://www.ligo.caltech.edu/

Advanced LIGO LIGO-T000092-02-D

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Table of Contents1 INTRODUCTION.....................................................................................................................................................7

1.1 PURPOSE...........................................................................................................................................................71.2 SCOPE................................................................................................................................................................7

1.2.1 PO Mirror Assembly and Telescope............................................................................................................71.3 DEFINITIONS.....................................................................................................................................................71.4 ACRONYMS.......................................................................................................................................................71.5 APPLICABLE DOCUMENTS................................................................................................................................8

1.5.1 LIGO Documents.........................................................................................................................................91.5.2 Non-LIGO Documents.................................................................................................................................9

2 GENERAL DESCRIPTION.................................................................................................................................10

2.1 SPECIFICATION TREE......................................................................................................................................102.2 PRODUCT PERSPECTIVE..................................................................................................................................10

2.2.1.1 Layout................................................................................................................................................................112.2.2 PO Mirror Assembly and Telescope Perspective......................................................................................12

2.3 PRODUCT FUNCTIONS.....................................................................................................................................122.3.1 PO Mirror Assembly and Telescope Functions.........................................................................................12

2.4 GENERAL CONSTRAINTS.................................................................................................................................122.4.1 PO Mirror Assembly and Telescope Constraints......................................................................................13

2.5 ASSUMPTIONS AND DEPENDENCIES................................................................................................................132.5.1 Core Optics Parameters............................................................................................................................132.5.2 Interferometer Design Parameters............................................................................................................142.5.3 ISC Interface Characteristics....................................................................................................................14

2.5.3.1 ISC Sensor Beam Parameters............................................................................................................................142.5.4 Seismic Environment.................................................................................................................................15

3 REQUIREMENTS.................................................................................................................................................16

3.1 PO MIRROR AND TELESCOPE REQUIREMENTS...............................................................................................163.1.1 Introduction...............................................................................................................................................163.1.2 PO Mirror and Telescope Characteristics................................................................................................16

3.1.2.1 PO Mirror and Telescope Performance Characteristics....................................................................................163.1.2.2 PO Mirror and Telescope Physical Characteristics...........................................................................................183.1.2.3 PO Mirror and Telescope Interface Definitions................................................................................................203.1.2.4 PO Mirror and Telescope Reliability................................................................................................................213.1.2.5 PO Mirror and Telescope Maintainability.........................................................................................................213.1.2.6 PO Mirror and Telescope Environmental Conditions.......................................................................................213.1.2.7 PO Mirror and Telescope Transportability........................................................................................................21

3.1.3 PO Mirror and Telescope Design and Construction................................................................................213.1.3.1 Materials and Processes.....................................................................................................................................213.1.3.2 PO Mirror and Telescope Workmanship...........................................................................................................223.1.3.3 PO Mirror and Telescope Interchangeability....................................................................................................223.1.3.4 PO Mirror and Telescope Safety.......................................................................................................................223.1.3.5 PO Mirror and Telescope Human Engineering.................................................................................................22

3.1.4 PO Mirror and Telescope Assembly and Maintenance.............................................................................223.1.5 PO Mirror and Telescope Documentation................................................................................................23

3.1.5.1 PO Mirror and Telescope Specifications...........................................................................................................233.1.5.2 PO Mirror and Telescope Design Documents...................................................................................................233.1.5.3 PO Mirror and Telescope Engineering Drawings and Associated Lists...........................................................233.1.5.4 PO Mirror and Telescope Technical Manuals and Procedures.........................................................................233.1.5.5 PO Mirror and Telescope Documentation Numbering.....................................................................................233.1.5.6 PO Mirror and Telescope Test Plans and Procedures.......................................................................................23

3.1.6 PO Mirror and Telescope Logistics..........................................................................................................233.1.7 PO Mirror and Telescope Precedence......................................................................................................243.1.8 PO Mirror and Telescope Qualification...................................................................................................24

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4 QUALITY ASSURANCE PROVISIONS...........................................................................................................25

4.1 GENERAL........................................................................................................................................................254.1.1 Responsibility for Tests..............................................................................................................................254.1.2 Special Tests..............................................................................................................................................25

4.1.2.1 Engineering Tests..............................................................................................................................................254.1.2.2 Reliability Testing.............................................................................................................................................25

4.1.3 Configuration Management.......................................................................................................................254.2 QUALITY CONFORMANCE INSPECTIONS..........................................................................................................25

4.2.1 Inspections.................................................................................................................................................254.2.2 Analysis......................................................................................................................................................264.2.3 Demonstration...........................................................................................................................................264.2.4 Similarity...................................................................................................................................................264.2.5 Test............................................................................................................................................................26

5 PREPARATION FOR DELIVERY.....................................................................................................................27

5.1 PREPARATION.................................................................................................................................................275.2 PACKAGING.....................................................................................................................................................275.3 MARKING........................................................................................................................................................27

6 Notes........................................................................................................................................................................28

AppendicesAppendix A Quality Conformance Inspections__________________________________________99

Table of TablesTable 16: Wavefront distortion of PO optical train..........................................................................16Table 17: Minimum Resonant Frequency of PO Mirror, ETM Telescope and APS/PO Telescope Mounted Next to a Multi-pendula COC............................................................................................19Table 23 Quality Conformance Inspections......................................................................................28

Table of FiguresFigure 1: Overall LIGO detector requirement specification tree......................................................10

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Abstract

This technical note is being generated to provide a general outline to be followed for developing a Design Requirements Document (DRD) for the LIGO Detector Group. The following pages provide the outline, including section/paragraph numbering and headings, along with a brief explanation (and some examples) of what is to go into each paragraph.

The basis for the following outline is a combination of the IEEE guide for software requirement documentation and the MIL-STD-490A guide to requirement specification. Sections 1 and 2 particularly follow the IEEE standard. The remaining sections are more in line with the MIL-STD format, with some extras or variations that I’ve found useful in the past.

This document is a MicroSoft Word template. All instructions (guidelines and examples) in this document are in normal text, and should be deleted when an individual DRD is written. This document also shows “boilerplate” text, which should appear in every LIGO detector DRD. This boilerplate appears in this document as italic text and should not be removed from individual DRDs.

This section (Abstract) was purposely titled without using the LIGO tech document template ‘Header’ paragraph format, such that the Table of Contents of this document directly reflects the outline for a DRD.

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1 Introduction

1.1 Purpose

The purpose of this document is to describe the design requirements for the Auxiliary Optics Support (AOS). Primary requirements are derived (“flowed-down”) from the LIGO principal science requirements. Secondary requirements, which govern Detector performance through interactions between AOS and other Detector subsystems, have been allocated by Detector Systems Engineering (see Figure 1.)

1.2 Scope

Identify the item to be produced by name, such as Alignment Sensing and Control.

Explain what the item will and, if necessary, will not do. An example of the latter, from the CDS document is: CDS specifically does not provide: 1) Personnel safety system 2) Facilities Control System 3) etc. The point is to emphasize to reviewers what the system will not do where there may be some doubt or uncertainty.

Describe the objectives, goals of the item development.

1.2.1 PO Mirror Assembly and Telescope

The PO Mirror Assembly and Telescope subsystem will generate optical pick-off (PO) beams from core optical elements and deliver those beams with a specified beam waist and location outside the vacuum housing for use by the LSC/ASC in the feedback control of the interferometer (IFO) alignment and length, and for monitoring purposes. These PO beams include the following: BS PO, ITMx PO, ITMy PO, ETMx transmitted beams, ETMy transmitted beams, and APS beam.

The PO Mirror Assembly and Telescope subsystem will provide viewport windows for the following beams: input PSL beam, SPS beam, Input Modecleaner ASC beam, and the PSL Intensity stabilization beam; it does not include other optical pick-off beams within the IO or PSL systems.

1.3 Definitions

Define all terms used in the document as necessary to interpret its contents. For example, a CDS specification may make use of terminology, such as “real-time software”, which is subject to interpretation. This section should specifically define what “real-time software” means in the context of this document.

NOTE: This should include all standard names used in interface discussions/drawings.

1.4 Acronyms

List all acronyms and abbreviations used in the document.

LIGO - Laser Interferometer Gravity Wave Observatory

COS - Core Optics Support

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IOO - Input Optics

DRD - Design Requirements Document

SRD - Science Requirements Document

RM - Recycling Mirror

BS - Beam Splitter

ITMx, ITMy - Input Test Mass in the interferometer ‘X’ or ‘Y’ arm

ETMx, ETMy - End Test Mass in the interferometer ‘X’ or ‘Y’ arm

AR - Antireflection Coating

HR - Reflective mirror coating

GBAR - Ghost Beam from AR side of COC

GBHR - Ghost Beam from HR side of COC

PO - Pick-off Beam

vh - Vacuum housing

SEI - Seismic Isolation subsystem

SUS - Suspension subsystem

ppm - parts per million

ISC- Interferometer Sensing and Control

LSC - Length Sensing and Control

COC - Core Optics Components

ASC - Alignment Sensing and Control

IFO - LIGO interferometer

HAM - Horizontal Access Module

BSC - Beam Splitter Chamber

BRDF - Bi-directional Reflectance Distribution Function

TBD - To Be Determined

APS - anti-symmetric port signal

SPS - symmetric port signal

rms - root-mean-square

p-v, peak to valley

1.5 Applicable Documents

List all documents referenced. Include only those expressly mentioned within this document.

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1.5.1 LIGO Documents

Core Optics Support Design Requirements Document lIGO-T970071-03-D

Core Optics Components DRD: LIGO-Exxx

ISC Reference Design

Seismic Isolation DRD, LIGO-T960065-02-D

Locally Damped Test Mass Motion, LIGO-T970092-00-D

Advanced LIGO Detector Design Requirements Document: LIGO-Exxx

Core Optics Support Conceptual Design, LIGO-T970072-00-D

COS Beam Dump and Stray Light Baffle Revised Req. and Concepts LIGO-T980103-00-D

Up-conversion of Scattered Light Phase Noise from Large Amplitude Motions, LIGO-T980101-00D

Effect of PO Telescope Aberrations on Wavefront Sensor Performance, LIGO-T980007-00-D

LIGO Vacuum Compatibility, Cleaning Methods and Procedures, LIGO-E960022-00-D

ASC Optical Lever Design Requirement Document, LIGO-T950106-01-D

LIGO-E000007-00

LIGO Naming Convention (LIGO-E950111-A-E)

LIGO Project System Safety Management Plan LIGO-M950046-F

LIGO EMI Control Plan and Procedures (LIGO-E960036)

Derivation of CDS Rack Acoustic Noise Specifications, LIGO-T960083

Specification Guidance for Seismic Component Cleaning, Baking, and Shipping Preparation (LIGO-L970061-00-D)

COS Preliminary Design T980010-01-D

1.5.2 Non-LIGO Documents

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2 General descriptionThis section (Section 2) should describe the general factors that affect the product and its requirements. This section does not state specific requirements; it only makes those requirements easier to understand.

2.1 Specification Tree

This document is part of an overall LIGO detector requirement specification tree. This particular document is highlighted in the following figure.

2.2 Product Perspective

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ITMy

ITMxRM BS


Figure 1: Overall LIGO detector requirement specification tree

2.2.1.1 Layout

A schematic layout of the detector assembly is shown in the figure following, indicating the physical relationship of the Stray Light Control subsystem elements to the rest of the detector system.

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ETMy

SMmodecleanerSPS

LEGEND

Elliptical Baffle

Cryopump Baffle

Arm Cavity Baffle

ETM Telescope

PO/APS Telescope

PO Mirror

Cavity Beam Dump

IO Baffle

Viewport

Modecleaner Baffle

Figure 2: Schematic Layout, Stray Light Control subsystem


2.2.2 PO Mirror Assembly and Telescope Perspective

The PO Mirror Assembly and Telescope subsystem contains pick-off (PO) mirrors mounted to a BSC optical table for directing PO beams to the PO telescopes that are mounted on a HAM optical table. An APS telescope, also mounted on the HAM optical table, will receive the APS beam from the anti-symmetric port. Beam steering periscopes and steering mirrors will direct the output beams from the telescopes through the AOS viewports in the HAM chamber to the ISC system outside the vacuum.

2.3 Product Functions

This section should provide a summary of the functions that the specified item will perform. This should just be general statements, not the detail that will go into the requirements section (Section 3).

2.3.1 PO Mirror Assembly and Telescope Functions

Ghost beams from the ITMx, ITMy, and BS mirrors will be used as PO beams for sensing and control (ISC) of the COC mirrors. The PO beams will be directed by PO mirror assemblies into beam reducing telescopes and will be subsequently directed with steering mirrors through vacuum viewports to the ISC photodetectors.

The PO beams and APS beam will exit through the vacuum chamber to a specified location with a specified beam waist and a specified wavefront distortion.

2.4 General Constraints

This section should give a general description of any other items that will limit the designer’s options, such as general policies, design standards, interfaces, etc. This subsection should not be

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used to impose specific requirements or specific design constraints on the solution. This subsection should provide the reasons why certain specific requirements or design constraints are later specified as part of Section 3. A CDS example for the CDS PSL document might be:

The overall CDS system is being developed using VME based systems as the standard interface. Therefore, all I/O modules being developed for the PSL will be constrained to this format.

Another general example might be:

LIGO must operate continuously, therefore this subsystem must be designed with high reliability and low mean time to repair. (Note that this is a general statement, and the MTBF and MTTR will be exactly specified in Section 3).

2.4.1 PO Mirror Assembly and Telescope Constraints

The input beam diameter shall include the 100 ppm diameter of the main interferometer beam. The output beam diameter shall be the same as LIGO 1. See Core Optics Support Design Requirements Document lIGO-T970071-03-D

2.5 Assumptions and Dependencies

This section should list factors that affect the requirements i.e. certain assumptions have been made in the writing of the requirements, and, if these change, then the requirements will have to be changed. For example, it is assumed that green light wavelengths will be used as the basis for optics requirements. If this is changed to infrared, then the requirements that follow will need to change.

2.5.1 Core Optics Parameters

See Core Optics Components DRD: LIGO-Exxx

Physical Quantity RM SM BS ITMx ITMy ETM

AR coating @ 1060 nm <0.0005 <0.0005 <0.0005 <0.0005 <0.0005

AR coating @ 940 nm >0.4 >0.4 >0.4 >0.4 NA

substrate thickness, cm 10 4 10 10 10

Mirror power loss fraction 0.00005 0.00005 0.00005

mirror reflectivity @ 1060 nm 0.97 0.5 0.995 0.995 0.99994

mirror reflectivity @ 940 nm >0.4 >0.4 >0.4 >0.4 >0.4

mirror reflectivity @ 670 nm >0.04 >0.04 >0.04 >0.04 >0.04

refractive index @ 1064 nm 1.44963 1.44963 1.7546 1.7546 1.7546

100ppm power contour radius, mm 116 116 116 116 116

1ppm power contour radius, mm 142 142 142 142 142

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beam radius parameter w, mm 54 54 54 54 54

Mirror diameter, mm 280 280 280 280 280

Mirror thickness, mm 120 120 120 120 120

2.5.2 Interferometer Design Parameters

The stray light calculations were based on the following assumed parameters:

Laser input power 125 watts

SPS power 2.5 watts

APS power 1.0 Watt

IFO Gaussian beam radius, w 54 mm

Recycling cavity gain 16.8

Arm cavity gain 789

2.5.3 ISC Interface Characteristics

2.5.3.1 ISC Sensor Beam Parameters

The COS PO beam characteristics will be compatible with the ISC design. ISC Reference Design:-________? The beam characteristics at the exit of the HAM viewport are as follows:

Physical Quantity Characteristic

Output PO beam aperture: APS, BS, ITM

20 mm

Output PO beam aperture: ETM

20 mm

wavefront distortion < 0.7 wave p-v

beam waist position TBD

Gaussian beam radius parameter

w = 4.2 mm

beam height Centered on the viewport

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beam orientation nominally horizontal

beam polarization horizontal (TBD)

2.5.4 Seismic Environment

The scattered light noise calculations in this document are based on the assumption that the rms velocity of scattering surfaces is sufficiently low so that up-conversion of large amplitude low fre-quency motion does not produce in-band phase noise. This is true for the vacuum housing and is also true of the SEI platforms for stack Q’s less than 1000. See Seismic Isolation DRD, LIGO-T960065-02-D, and Locally Damped Test Mass Motion, LIGO-T970092-00-D.

The ground noise spectrum for the scattered light noise calculations is assumed to be the LIGO Composite Ground Noise Spectrum for frequencies between 10 and 1000 Hz, as described in figure 10, LIGO-T960065.

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3 RequirementsThis section contains the specific requirements of the product to be developed. This is the most important part of the document. It must be:

Unambiguous: every requirement listed has only one interpretation

Complete: Inclusion of all significant requirements

Verifiable: A requirement is verifiable if and only if there exists some finite cost-effective process whereby the final product can be checked/tested to meet the requirement. If no method can be devised to determine if the product meets a particular requirement, either (1) the requirement should be removed, or (2) a point in the development cycle should be identified at which the requirement can be put into a verifiable form.

Consistent: No two requirements should conflict with each other.

Modifiable: The structure and style should be such that any necessary changes can be made easily, completely, and consistently.

Traceable: Backward (references to source of requirements, such as a higher level specification, design, or standards) and Forward (unique numbering of requirements such that they can be identified/referenced in design and test documentation).

Usable during operations and maintenance: often items are modified during commissioning and maintenance periods. The requirements should specifically call out critical areas (such as failure of this component to meet this requirement can cause severe injury), and other such items, such that this fact s not lost to maintenance personnel.

3.1 PO Mirror and Telescope Requirements

3.1.1 Introduction

Requirements flow down tree from Detector DRD should be included in this section.

The requirements for the APS beam, the ITM and BS PO beams, and the ETM monitor beam will be identical to the LIGO 1 requirements, with the exception of the larger beam diameter requirement for Advanced LIGO.

3.1.2 PO Mirror and Telescope Characteristics

3.1.2.1 PO Mirror and Telescope Performance Characteristics

3.1.2.1.1 APS, ITM, and BS PO Beams

3.1.2.1.1.1 Wavefront Distortion

The PO Mirror, APS Telescope, PO Telescope, Steering Mirrors, and output viewports shall not cause excessive wavefront distortion of the PO beams. A total wavefront distortion in the optical

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train of < 0.9 waves will maintain the WFS signal contrast ratio >5:1; see Effect of PO Telescope Aberrations on Wavefront Sensor Performance, LIGO-T980007-00-D.

The wavefront distortion contributed by each of the optical elements in the optical train is random, and the total distortion is the rms sum of the individual distortions. The budgeted distortion for each element in the optical train and the total rms distortion in the optical train is shown below.

Table 1: Wavefront distortion of PO optical train

Element Distortion, waves @ 633 nm Distortion, waves @ 1064 nm

PO mirror 0.25 0.15

Steering mirror 0.10 0.06

viewport 0.23 0.13

telescope mirror 0.25 0.15

Faraday isolator 0.70 0.42

ISC lens 0.25 0.15

Attenuator plate 0.25 0.15

SPS optical train 0.63 0.37

APS optical train 1.15 0.69

ITM PO optical train 0.68 0.40

BS PO optical train 0.73 0.44

ETM monitor optical train 0.62 0.37

3.1.2.1.1.2 Clear Input Aperture, PO and APS Beams

The clear input aperture for the PO and APS beams shall be > 100 ppm intensity profile diameter of the main beam, which is assumed to be equal to 232mm diameter.

3.1.2.1.1.3 Telescope De-magnification Ratio, PO and APS Telescopes

The input beam diameter at the 100 ppm intensity profile is 232 mm, and the output beam diameter delivered to the ISC system will be 19.3 (the same as LIGO 1); therefore the required demagnification ratio of the telescope shall be 12:1.

3.1.2.1.1.4 Clear Output Aperture, PO and APS Beams

The clear output aperture for the PO and APS beams shall be > 100 ppm intensity profile diameter of the de-magnified main beam, which is assumed to be equal to (1/12)*232mm = 19mm diameter.

3.1.2.1.1.5 Optical Train Transmissivity

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The APS optical train transmissivity will be maximized with the use of ion-beam antireflection coatings and dielectric high reflection coatings wherever possible. The expected transmissivity for the APS optical train will be >96%.

The PO optical train elements will use commercial antireflection coatings and high reflection coatings. The expected transmissivity for the PO optical trains is >88%.

3.1.2.1.1.6 Field-of-View

The PO and APS telescopes shall provide an angular field-of-view of +/- 0.0004 rad to allow for possible beam shifts and other misalignment errors during the interferometer pump-down. This requirement is derived in COS Preliminary Design T980010-01-D.

3.1.2.1.2 ETM Monitor Beam

3.1.2.1.2.1 Wavefront Distortion

N/A

3.1.2.1.2.2 Clear Input Aperture, ETM Telescope

The input aperture will be the same diameter as the LIGO 1 ETM telescope, 160mm diameter

3.1.2.1.2.3 Telescope De-magnification Ratio, ETM Telescopes

The input aperture is 160 mm, and the output aperture will be 20 (the same as LIGO 1); therefore the required demagnification ratio of the telescope shall be 8:1

3.1.2.1.2.4 Optical Train Transmissivity

The ETM monitor optical train elements will use commercial antireflection coatings and high reflection coatings. The expected transmissivity for the ETM monitor optical train is >96%.

3.1.2.1.2.5 Field-of-View

N/A

3.1.2.2 PO Mirror and Telescope Physical Characteristics

3.1.2.2.1 Vacuum compatibility of COS elements

3.1.2.2.1.1 Outgassing of COS elements

The COS elements shall be fabricated from materials whose outgassing properties are compatible with the vacuum requirements of the LIGO. See LIGO Vacuum Compatibility, Cleaning Methods and Procedures, LIGO-E960022-00-D

3.1.2.2.2 Access for Optical lever beams and TV Camera Viewing of COCs

The PO Mirror and telescope assemblies shall allow access to the optical lever beams and TV camera viewing of the COC elements. See ASC Optical Lever Design Requirement Document, LIGO-T950106-01-D

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3.1.2.2.3 Optical Alignment of COS

The AOS telescopes shall be pre-aligned before assembly into the IFO vacuum housing.

The AOS telescopes and optical beam-dump/baffles shall be final aligned to the IFO optical cen-terline and ghost beam centerlines during the initial IFO optical alignment.

3.1.2.2.4 Resonant Frequency of AOS Elements Mounted on the Optics Platform

The resonant frequencies and Q’s of the PO mirrors and Telescopes and accessory optics which are mounted to the optics platforms shall not cause excessive induced thermal-noise of the test mass.

The advanced LIGO requirement for thermally induced noise amplitude impressed on the test mass shall not exceed

in the frequency band 10-1000Hz. See LIGO-Exxx.

The maximum thermal noise amplitude occurs at resonance, and the minimum resonant frequency which meets the requirement is given by

The maximum thermal motion induced in the SEI platform can be smaller than the maximum thermal noise amplitude requirement at the mirror because the motion is attenuated by the test mass

suspension system. The attenuation factor for N multi-pendula, for f>f0 , is given by

The minimum resonant frequency of the PO Mirror and PO telescope that will not exceed the induced thermal noise requirement are shown in the following.

Table 2: Minimum Resonant Frequency of PO Mirror, ETM Telescope and APS/PO Telescope Mounted Next to a Multi-pendula COC

Gravity wave frequency 10 Hz 100 Hz 10 00Hz

No. of COC pendulum stages 3 3 3

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Gravity wave frequency 10 Hz 100 Hz 10 00Hz

Thermal noise amplitude requirement on SEI table, m/Hz^0.5

1E-15 1E-9 1E-6

Multi-pendula attenuation factor 5.7E-7 5.7E-13 5.7E-19

Mass of ETM telescope, kg 13.6 13.6 13.6

Mass of PO mirror, kg 13.6 13.6 13.6

Q of PO mirror and ETM/APS/PO telescope 10 10 10

Minimum resonant frequency of PO mirror, Hz 63 1E-2 1E-6

Minimum resonant frequency of ETM telescope, Hz 63 1E-2 1E-6

Mass of PO telescope, kg 63.5 63.5 63.5

Minimum resonant frequency of PO telescope, Hz 106 1E-2 1E-6

3.1.2.3 PO Mirror and Telescope Interface Definitions

3.1.2.3.1 Interfaces to other LIGO detector subsystems

3.1.2.3.1.1 Mechanical Interfaces

The PO Mirrors shall mount to the SEI platforms, in the BSC chambers, without interfering with the COC mirror structures.

The Telescopes and associated optical train elements shall mount to the SEI platform in the BSC and HAM chambers, without interfering with the COC mirror structures.

The viewport windows shall mount to the existing ports in the HAM chamber and BSC chamber doors.

3.1.2.3.1.2 Electrical Interfaces

There are no electrical interfaces.

3.1.2.3.1.3 Optical Interfaces

The Telescopes shall provide a large enough field of view so that the PO beams and APS beams will be properly acquired before and after pump-down of the vacuum chambers.

The output beams from the Telescopes will be steered through the centers of the viewports in the appropriate HAM and BSC chambers and shall be accessible to the ISC system.

3.1.2.3.1.4 Stay Clear Zones

The PO mirrors and Telescopes shall maintain a stay clear zone of >34 mm from the 1ppm margin of the main interferometer beam.

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3.1.2.4 PO Mirror and Telescope Reliability

All PO Mirror and Telescope elements are passive and are expected to have a 100% availability. The MTBF is expected to be equal to the life of the detector.

3.1.2.5 PO Mirror and Telescope Maintainability

Spare components will be stocked for the replacement during installation of long lead time items such as telescope mirrors and lenses.

3.1.2.6 PO Mirror and Telescope Environmental Conditions

The PO Mirror and Telescope elements will operate in a temperature and humidity controlled laboratory environment. Prior to assembly, the components of the PO Mirror and Telescope subsystem can be subjected to normal commercial shipping and handling environments.

3.1.2.7 PO Mirror and Telescope Transportability

All items shall be transportable by commercial carrier without degradation in performance. As necessary, provisions shall be made for measuring and controlling environmental conditions (temperature and accelerations) during transport and handling. Special shipping containers, shipping and handling mechanical restraints, and shock isolation shall be utilized to prevent damage. All containers shall be movable for forklift. All items over 100 lbs. which must be moved into place within LIGO buildings shall have appropriate lifting eyes and mechanical strength to be lifted by cranes.

3.1.3 PO Mirror and Telescope Design and Construction

The design and construction of the PO Mirror and Telescope subsystem allow adequate cleaning, either on site or at an appropriate outside vendor, and shall fit inside the vacuum baking ovens on site.

3.1.3.1 Materials and Processes

The materials and processes used in the fabrication of the PO Mirror and Telescope subsystem shall be compatible with the LIGO approved materials list.

3.1.3.1.1 Finishes

• Metal components shall have quality finishes on all surfaces, suitable for vacuum finishes. All corners shall be rounded to TBD radius.

• All materials shall have non-shedding surfaces.

• Aluminum components used in the vacuum shall not have anodized surfaces.

3.1.3.1.2 Materials

A list of currently approved materials for use inside the LIGO vacuum envelope can be found in LIGO Vacuum Compatible Materials List (LIGO-E960022). All fabricated metal components exposed to vacuum shall be made from stainless steel, copper, or aluminum. Other metals are subject to LIGO approval. Pre-baked viton (or fluorel) may be used subject to LIGO approval. All

20


materials used inside the vacuum chamber must comply with LIGO Vacuum Compatibility, Cleaning Methods and Procedures (LIGO-E960022-00-D).

The only lubricating films permitted within the vacuum are dry plating of vacuum compatible materials such as silver and gold.

3.1.3.1.3 Processes

All materials used inside the vacuum chambers must be cleaned in accordance LIGO-E960022-00-D or LIGO-E000007-00, and Specification Guidance for Seismic Component Cleaning, Baking, and Shipping Preparation (LIGO-L970061-00-D). To facilitate final cleaning procedures, parts should be cleaned after any processes that result in visible contamination from dust, sand or hydrocarbon films.

Materials shall be joined in such a way as to facilitate cleaning and vacuum preparation procedures; i. e. internal volumes shall be provided with adequate openings to allow for wetting, agitation and draining of cleaning fluids and for subsequent drying.

3.1.3.1.4 Component Naming

All components shall be identified using the LIGO Naming Convention (LIGO-E950111-A-E). This shall include identification (part or drawing number, revision number, serial number) physically stamped on all components, in all drawings and in all related documentation.

3.1.3.2 PO Mirror and Telescope Workmanship

All components shall be manufactured according to good commercial practice.

3.1.3.3 PO Mirror and Telescope Interchangeability

Common elements, with ordinary dimensional tolerances, will be interchangeable. Certain telescope elements with unusually tight dimensional tolerances, such as the ETM telescope focus barrel, will be manufactured as matched sets and will not be interchangeable.

3.1.3.4 PO Mirror and Telescope Safety

This item shall meet all applicable NSF and other Federal safety regulations, plus those applicable State, Local and LIGO safety requirements. A hazard/risk analysis shall be conducted in accordance with guidelines set forth in the LIGO Project System Safety Management Plan LIGO-M950046-F, section 3.3.2.

3.1.3.5 PO Mirror and Telescope Human Engineering

NA

3.1.4 PO Mirror and Telescope Assembly and Maintenance

Assembly fixtures and installation procedures shall be developed in conjunction with the Stray Light Control hardware design. These shall include (but not be limited to) fixtures and procedures for:

• installation and assembly of beam dumps and baffles into the vacuum

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• assembly of the in vacuum components in a clean room (class 100) environment

3.1.5 PO Mirror and Telescope Documentation

The documentation shall consist of working drawings, assembly drawings, and alignment procedures.

3.1.5.1 PO Mirror and Telescope Specifications

Specifications for the purchase of specialized components and assemblies such as Faraday isolator, optical mirrors, windows, and lenses shall be developed.

3.1.5.2 PO Mirror and Telescope Design Documents

The following documents will be produced:

• PO Mirror and telescope Preliminary Design Document (including supporting technical design and analysis documentation)

• PO Mirror and telescope Final Design Document (including supporting technical design and analysis documentation)

• PO Mirror and telescope Installation Procedures

3.1.5.3 PO Mirror and Telescope Engineering Drawings and Associated Lists

A complete set of drawings suitable for fabrication must be provided along with Bill of Material (BOM) and drawing tree lists. The drawings must comply with LIGO standard formats and must be provided in electronic format. All documents shall use the LIGO drawing numbering system, be drawn using LIGO Drawing Preparation Standards, etc.

3.1.5.4 PO Mirror and Telescope Technical Manuals and Procedures

3.1.5.4.1 Procedures

Procedures shall be provided for the installation, and final alignment of the Pickoff Mirror and Telescope elements.

3.1.5.5 PO Mirror and Telescope Documentation Numbering

All documents shall be numbered and identified in accordance with the LIGO documentation control numbering system LIGO document TBD

3.1.5.6 PO Mirror and Telescope Test Plans and Procedures

All test plans and procedures shall be developed in accordance with the LIGO Test Plan Guidelines, LIGO document TBD.

3.1.6 PO Mirror and Telescope Logistics

The design shall include a list of all recommended spare parts and special test equipment required.

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3.1.7 PO Mirror and Telescope Precedence

The relative importance of the PO Mirror and Telescope subsystem requirements are as follows:

1) clear aperture through the APS and PO optical trains

2) optical transmissivity through the APS and PO optical trains

3) compatibility with COC elements

3.1.8 PO Mirror and Telescope Qualification

N/A

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4 Quality Assurance ProvisionsThis section includes all of the examinations and tests to be performed in order to ascertain the product, material or process to be developed or offered for acceptance conforms to the requirements in section 3.

4.1 General

This should outline the general test and inspection philosophy, including all phases of development.

4.1.1 Responsibility for Tests

Who is responsible for testing.

4.1.2 Special Tests

4.1.2.1 Engineering Tests

List any special engineering tests that are required to be performed. Engineering tests are those which are used primarily for the purpose of acquiring data to support the design and development.

4.1.2.2 Reliability Testing

Reliability evaluation/development tests shall be conducted on items with limited reliability history that will have a significant impact upon the operational availability of the system.

4.1.3 Configuration Management

Configuration control of specifications and designs shall be in accordance with the LIGO Detector Implementation Plan.

4.2 Quality conformance inspections

Design and performance requirements identified in this specification and referenced specifications shall be verified by inspection, analysis, demonstration, similarity, test or a combination thereof per the Verification Matrix, Appendix 1 (See example in Appendix). Verification method selection shall be specified by individual specifications, and documented by appropriate test and evaluation plans and procedures. Verification of compliance to the requirements of this and subsequent specifications may be accomplished by the following methods or combination of methods:

4.2.1 Inspections

Inspection shall be used to determine conformity with requirements that are neither functional nor qualitative; for example, identification marks.

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4.2.2 Analysis

Analysis may be used for determination of qualitative and quantitative properties and performance of an item by study, calculation and modeling.

4.2.3 Demonstration

Demonstration may be used for determination of qualitative properties and performance of an item and is accomplished by observation. Verification of an item by this method would be accomplished by using the item for the designated design purpose and would require no special test for final proof of performance.

4.2.4 Similarity

Similarity analysis may be used in lieu of tests when a determination can be made that an item is similar or identical in design to another item that has been previously certified to equivalent or more stringent criteria. Qualification by similarity is subject to Detector management approval.

4.2.5 Test

Test may be used for the determination of quantitative properties and performance of an item by technical means, such as, the use of external resources, such as voltmeters, recorders, and any test equipment necessary for measuring performance. Test equipment used shall be calibrated to the manufacture’s specifications and shall have a calibration sticker showing the current calibration status.

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5 Preparation for DeliveryPackaging and marking of equipment for delivery shall be in accordance with the Packaging and Marking procedures specified herein.

5.1 Preparation

• Vacuum preparation procedures as outlined in LIGO Vacuum Compatibility, Cleaning Methods and Procedures (LIGO-E960022-00-D) shall be followed for all components intended for use in vacuum. After wrapping vacuum parts as specified in this document, an additional, protective outer wrapping and provisions for lifting shall be provided.

• Electronic components shall be wrapped according to standard procedures for such parts.

5.2 Packaging

Procedures for packaging shall ensure cleaning, drying, and preservation methods adequate to prevent deterioration, appropriate protective wrapping, adequate package cushioning, and proper containers. Proper protection shall be provided for shipping loads and environmental stress during transportation, hauling and storage. The shipping crates used for large items should use for guidance military specification MIL-C-104B, Crates, Wood; Lumber and Plywood Sheathed, Nailed and Bolted. Passive shock witness gauges should accompany the crates during all transits.

For all components which are intended for exposure in the vacuum system, the shipping preparation shall include double bagging with Ameristat 1.5TM plastic film (heat sealed seams as practical, with the exception of the inner bag, or tied off, or taped with care taken to insure that the tape does not touch the cleaned part). Purge the bag with dry nitrogen before sealing.

5.3 Marking

Appropriate identification of the product, both on packages and shipping containers; all markings necessary for delivery and for storage, if applicable; all markings required by regulations, statutes, and common carriers; and all markings necessary for safety and safe delivery shall be provided.

Identification of the material shall be maintained through all manufacturing processes. Each component shall be uniquely identified. The identification shall enable the complete history of each component to be maintained (in association with Documentation “travelers”). A record for each component shall indicate all weld repairs and fabrication abnormalities.

For components and parts that are exposed to the vacuum environment, marking the finished materials with marking fluids, die stamps and/or electro-etching is not permitted. A vibratory tool with a minimum tip radius of 0.005" is acceptable for marking on surfaces that are not hidden from view. Engraving and stamping are also permitted.

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6 NotesThis section should contain information of a general or explanatory nature, and no requirements shall appear here. This could be such items as modeling data/results, R&D prototype information, etc.

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Appendix A Quality Conformance Inspections

Appendixes are used to append large data tables or any other items which would normally show up within the body of the specification, but, due to their bulk or content, tend to degrade the usefulness of the specification. Whenever an Appendix is used, it shall be referenced in the body of the specification.

Appendix 1 shall always contain a table that lists the requirements and the method of testing requirements. An example table follows. Additional appendixes can contain other information, as appropriate to the subsystem being specified.

Table 3 Quality Conformance Inspections

Paragraph Title I A D S T

3.2.1 Performance Characteristics

X

3.2.1.1 Controls Performance

X

3.2.1.2 Timing Performance‘

X X

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