Large Binocular Telescope Project

Attachment A to the RFP for the

Thin Secondary shell

STATEMENT OF WORK

27 February 2006

 

TABLE OF CONTENTS

1. Description of Tasks

2. Procedures

3. Documents

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1. Description of Tasks

1.1 Supply Description

1.1.1 Thin Secondary Shell & Transportation Box

Thin Zerodur shells provide the large flexible element for the adaptive secondary mirrors of the Large Binocular Telescope. The telescope is Gregorian in configuration, so the secondary mirrors are concave ellipsoids. Each thin shell will have 672 magnets glued to the rear side in order to provide rapidly variable support forces. A metallized pattern on the rear surface of the thin shell serves as part of a group of capacitive sensors to provide position feedback to each of the voice-coil actuators.

This Supply is to provide one (1) of these thin secondary shells. Two very specific aspects of the thin secondary shell are that:

·         It will require polishing a highly aspherical (ellipsoidal) optical surface of nearly 1 meter diameter.

·         It will require reducing the substrate thickness to a very unusual value (~1.6 mm), with implications on fabrication (thinning) and handling aspects.

In detail, the Supply includes:

  • Procuring the Zerodur substrate
  • Designing and procuring the necessary optical test equipment
  • Generating, polishing and figuring the aspheric optical surface
  • Preparation of the Optical Test and Metrology Reports
  • Designing and procuring the necessary thin shell handling equipment
  • Reducing the substrate thickness to the unusual value of ~1.6 mm
  • Trimming the shell to final dimensions of inside and outside diameter
  • Application of a patterned metalized coating to the back surface of the shell
  • Designing and procuring a transportation box suitable for multiple (3) trans-Atlantic shipments of the shell
  • Packing, shipping and delivery of the coated thin shell to Lecco, Italy

1.1.1.1 Guidelines for technical proposals

LBTO is assuming that most, if not all, proposals will be based on the technique in which the required mirror shape will be obtained by polishing (with any suitable method) the front (optical, concave) face on a relatively thick substrate; and then the required thickness will be obtained by thinning the substrate (with any suitable technique) acting on its rear (convex) side.

Proposals not based on the above general approach (called “Front Face First”, FFF) will be considered.

 

All the logical steps of the proposed production scheme must be clearly listed and briefly described from the technical point of view, with particular attention to the following aspects:

 

  • Technique proposed for the final aspherical polishing
  • Technique proposed for optical testing and metrology
  • Technique proposed for the thinning and final polishing of the back face after thinning
  • Technique proposed for obtaining the final mirror dimensions (central hole, outer diameter)
  • Technique proposed for removing the thin mirror from the support used during thinning and rear face polishing phases
  • Technique proposed for thin mirror handling
  • Technique proposed for coating the back face in the prescribed geometry.

 

The proponents should provide references (articles, web pages, unpublished reports) or report directly on any previous experience on any of these technical aspects that is considered relevant for this work.

 

1.1.1.2 Recommendations on specific technical aspects

 

Previous experience in the production of identical units has shown that the following precautions can significantly help in obtaining the specified tolerances and in reducing the production time:

 

  • High grade Zerodur (special grade class 1) with the lowest value of internal stress, 10nm/cm, is required to guarantee full performance compatibility of the spare mirror with the other ones.  Alternative materials do not need to be explored (and will not be accepted).
  • It is advisable to polish a blank (of the above material) that is significantly oversized with respect to the final mirror diameter of 911 mm.  Although this increases slightly the cost of the blank, of the polishing, and of the edge trimming, it greatly simplifies achieving the high spatial frequency tolerances up to the very edge of the final mirror, as required.
  • It is very advisable to use, during the thinning operation, a support (“blocking body”) with a coefficient of thermal expansion fairly close to that of Zerodur (low grade Zerodur or equivalents of different manufacturers, ULE …).  Materials with much larger CTE (even worse if anisotropic, like granite) tend to produce warping of the thin mirror during thinning in the presence of moderate temperature changes.

1.1.2 Technical Specifications

The thin shell will be polished in accordance with the Large Binocular Telescope Project's Technical Specification 645s001 and associated dimensional drawing 645a004.

The backside coating will be applied in accordance with the Large Binocular Telescope Project's Technical Specification 645s020 and associated dimensional drawing 645s011.

The transportation box will be fabricated in accordance with industry standards and should be suitable for trans-Atlantic shipment of the shell by commercial air freight.

1.1.3 Shipping

The Supply includes the packing and shipping of the completed thin shell to the premises of ADS International in Lecco, Italy.  After approximately 9 months of integration and testing in Italy, the thin shell will be shipped to its ultimate destination in Arizona. (Transportation to Arizona is not included in this Supply.)

1.2 Deliverable Hardware

1.2.1 Hardware to be manufactured or supplied

Listed below are all the hardware components to be delivered as part of this Supply.

  • Thin Secondary Shell for LBT672 (quantity=1)
  • Transportation Box for the Thin Shell (quantity=1)

1.3 Deliverable Documents

Described in this section are all the plans, drawings and documentation that must be supplied as part of this Statement of Work. All documents shall be supplied in two (2) hard copies and one (1) digital copy. All the deliverable documents, once accepted by the LBTPO, become property of LBT Corporation. These documents include:

  • Acceptance Test Plans
  • Test Procedures
  • Test Reports
  • "As Built" Drawings

Documentation packages shall be supplied in support of the following functional activities:

1.3.1 Optical Testing of the Mirror Figure

1.3.1.1 Acceptance Plan

Prepare and submit for approval an Acceptance Plan describing test procedures and inspections that shall be performed prior to acceptance of the optical surface at the end of polishing. The Acceptance Plan must be submitted to the Technical Representative for approval before starting the optical fabrication. The Technical Representative shall comment on the request within 15 days from the receipt, and in the event of no comment the request is to be considered approved.

The different optical and mechanical metrology systems to be used in the various phases of the production must be identified and their basic properties (e.g. accuracy level, resolution on the mirror), briefly described, in particular for those that will be used for progress reports and for final acceptance.

1.3.1.2 Test Procedures

The Test Procedures shall describe in detail all the necessary operations to perform verification through a test. A Test Procedure shall be produced for every verification test required and shall contain the following information:

  • Scope of the Test -- In this section the scope of the test shall be described and the verification item shall be identified.
  • Applicable Documents -- In this section all the documents referred to in the Test Procedure shall be listed.
  • Test Conditions -- In this section all applicable requirements needed to correctly perform the test shall be listed and discussed (for instance: special environmental conditions, dedicated tools, test rigs, special requirements on the tested items, etc.), calibration requirements.
  • Test Procedure -- In this section all the operations required to perform the test shall be described in detail.
  • Test Results Presentation -- In this section the procedures to process the raw data for the final presentation of the test results shall be described.

The Test Procedure shall be submitted for review prior to performing the test and shall also be incorporated in the specific Test Report.

1.3.1.3 Test Reports

The Test Reports shall summarize the findings of the tests. The Test Report shall be submitted to the LBTC not later than 30 days after the test. A Test Report shall contain the following information:

  • Test Results -- In this section the findings of the test shall be given. The results shall be processed in such a way that they are directly comparable with the items to be verified.
  • Conclusions -- In this section a statement concerning the conformance of the test results with the requirements specified shall be given. Non-conformities and changes shall be discussed as far as applicable.

1.3.2 Metrology of Thin Shell Dimensions and Coating

1.3.2.1 Metrology Plan

Prepare and submit for approval a Metrology Plan describing test procedures and inspections that shall be performed prior to acceptance of the shell after thinning. The Metrology Plan must be submitted to the Technical Representative for approval before starting the thinning process. The Technical Representative shall comment on the request within 15 days from the receipt, and in the event of no comment the request is to be considered approved.

1.3.2.2 Test Procedures

See above.

1.3.2.3 Test Reports

See above.

1.3.3 Transportation Box

1.3.3.1 Storage and Shipping Plan

Prepare a Storage and Shipping Plan and submit it to the Technical Representative(s) for approval. The plan should provide detailed instructions regarding protective coating, packing, unpacking and handling of the Thin Shell. The Plan should provide the determination of volume and weight in relation to the transportation means. The Storage and Shipping Plan must be submitted to the Technical Representative for approval before starting the construction and materials purchase for the Transportation Box. The Technical Representative shall comment on the request within 15 days from the receipt, and in the event of no comment the request is to be considered approved.

1.3.3.2 As-Built Drawings

The LBTPO shall receive copies of the updated "as-built" drawings and documentation not later than 30 days after the completion of the acceptance tests. All drawings shall be prepared with AUTOCAD 2004, MDT6 or compatible format. All the assembly and sub-assembly drawings shall include the following information:

  • Number of the pieces required
  • Detailed drawings of the pieces
  • Third party manufacturer reference identification
  • The calculated partial and total weights

The test and inspections shall also include:

  • certificate of raw material and fasteners
  • certification of welding procedure and welding control
  • stress relief certification
  • dimensional control, machining tolerances
  • mass check
  • pre-assembly

1.3.4 Progress Reports to the LBTC

Reports on the status of the work covered by this contract should be sent to the LBTPO every two months. The Progress Report shall include an update of the initially proposed schedule (section 3.6.1 of the Proposal format).

2. Procedures

2.1 Acceptance

The Work shall be accepted by LBTC upon delivery and completion of the Work (including the acceptance tests in the factory and a post-delivery inspection) in a manner at that time satisfactory to LBTC.

2.2 Technical Liaison

The Supplier shall provide access to all phases of the Work to the following LBTC Technical Representative(s):

 

 
TECHNICAL REPRESENTATIVE TO BE NAMED AT THE TIME OF CONTRACT AWARD

The Supplier shall maintain informal technical liaison with the LBT Project Technical Representative(s). These representative(s) shall be provided the following:

  • Timely notification of all meetings concerning the Work (i.e., technical reviews, program planning meetings, problem solving sessions, etc.).
  • Access to data relating to analyses and other technical matters directly pertaining to the work being performed.
  • Access to all test procedures and test data.
  • Immediate notification of any significant problems.

2.3 Technical Changes

All ECRs, NCRs, and Requests for Waivers or Deviations will be presented to the Technical Representative(s) for further evaluation, formulation of responses, and recommendations to the LBT Director.

2.3.1 Engineering Change Request

In the event that the Supplier deems it necessary to deviate from any specification or term of the Technical Specifications or the Proposal, the Supplier shall deliver to the Technical Representative(s) an Engineering Change Request (ECR) setting forth:

  • Identification of Statement of Work
  • The description and justification of the change requested
  • An assessment of the impact of the change on the programmatic, costs, functional and performance requirements of the (Work) at any level

2.3.2 Non-Conformance Report (NCR)

The Supplier shall report all non-conformities from the Technical Specifications which occur during the manufacture, assembly, or testing at all levels of the Work. Each Non-Conformance Report shall set forth the following:

  • Identify the Statement of Work
  • Identify the item where the nonconformity occurs
  • Identify the originator
  • Describe the nonconformity in detail
  • List the documents and the hardware affected
  • Describe the impact at any level of the Work
  • Recommendation for further procedures

2.3.3 Request for Waiver/Deviation

A Request for Waiver may be issued during the manufacturing, test or integration of a deliverable item to:

  • request a relief from the relevant specifications, test procedure, assembly requirements and/or
  • request permission to use different hardware items or materials due to the inability to procure the specified ones in time to meet the schedule.

A granted waiver does not lead to changes of any approved and released documents. The Request for Waiver shall include:

  • Definition of the item affected
  • Identification of documents, and hardware affected
  • Description of the waiver
  • Description of the need for the waiver
  • Effects on costs and schedule

It shall be accompanied by all documentation required by the LBT Corporation to judge the acceptability of the waiver. If any change in the schedule or performance are expected, these points shall be clearly addressed.

2.4 Point of Delivery

All documents shipped as a result of this Statement of Work shall be sent to the LBT Project Office:

LBT Project Office
The University of Arizona
933 N Cherry Avenue
Tucson, AZ  85721-0065
USA

telephone: +1 520 626 5231

All hardware shipped as a result of this Statement of Work shall be sent to:

ADS International, s.r.l.
Via Roma, 87
23868 Valmadrera (LC)
Italy

telephone: +39 0341 210950

3. Documents

3.1 Applicable Drawings and Documents

Document
Type

Drawing
CAN #

Revision
Date

Assembly / Part Name

Technical Specification

645s001d.htm

06 January 2006

Polishing Specification for LBT672 F/15 Adaptive Secondaries

Autocad Drawing

645a004f.dwg
645a004f.pdf

26 January 2006

Deformable Mirror Shell for LBT672
(shell dimensions)

Technical Specification

645s020b.doc
645s020b.pdf

20 February 2006

Metallic coating specification of the convex (actuator) side
of the LBT Adaptive Secondary thin shell

Autocad Drawing

645s011a.dwg
645s011a.pdf

16 February 2006

Deformable Mirror Shell for LBT672
Concave Side Shell Aluminum Pattern

 

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