VST Project. M1floatation_VST-TRE-OAC Rel2.0. VST Project. Recovery Plan. M1 Floatation Support System

Transcription

1 Pag. 1 of 41 VST Project Recovery Plan Doc. : Issue: 2.0 Date: 8-mag-07 Name Date Signatures Prepared by M. Brescia 23 Apr 07 Integrated by D. Fierro, O. Caputi, F. Perrotta, 07 May 07 G. Marra, L. Ferragina Approved by M. Capaccioli Released by G. Sedmak 1

2 Pag. 2 of 41 Revisions Issue Author Date Section/Paragraph Affected 1.0 M. Brescia 23/04/2007 All First issue 1.1 M. Brescia 26/04/ Reason/Initiation/ Documents/Remarks created modified some task times and man power distribution 1.2 D. Fierro 03/05/ preliminary note for axial support solution 2.0 O. Caputi, G. Marra, F. Perrotta 07/05/ preliminary note for radial support solution first set of optical analysis & requirements reference to M1 cell + actuator FEA document 2

3 Pag. 3 of 41 INDEX 1 Reference/Applicable Documents Abbreviations and Acronyms Introduction Definition of Summary assessment of the documentation and RIXs for VST Strategy, Requirements and Specification M1 support system specification Strategy for M1 floatation support system Anti-turning system Axial and radial hardpoints M1 handling tool and mirror integration in the cell procedure Requirements and Specifications for M1 floatation support system Optical requirements and specification (contents by G. Marra) FE analysis specifications and results (contents by F. Perrotta) Mechanical requirements and specification Axial Supports (contents by D. Fierro) Radial Supports (contents by O. Caputi) Anti-turning System (contents by L. Ferragina) M1 Handling System (contents by L. Ferragina) M1 Floatation support system Work Breakdown Structure Description of Work Packages Work Package Deliverables Analytical Cost Allocation of WPs Time and man power Instruments and facilities Consulting Gantt activity diagram

4 Pag. 4 of 41 TABLE INDEX Tab. 1 Reference Documents... 5 Tab. 2 Abbreviations and acronyms... 6 Tab. 3 Sub-systems related to M1 floatation handling Tab. 4 Optical requirements Tab. 5 Optical Analysis Specifications Tab. 6 Mechanical requirements for radial support system Tab. 7 Mechanical analysis specification for radial support system () Tab. 8 Mechanical requirements for anti-turning system Tab. 9 Mechanical Analysis Specifications for anti-turning system Tab. 10 Mechanical requirements for M1 handling system Tab. 11 Mechanical Analysis Specifications for M1 handling system Tab. 12 Work Breakdown Structure Tab. 13 Work Breakdown Structure and Work Packages Tab. 14 Description of Work Package 1 and related tasks Tab. 15 Description of work package 2 and related tasks Tab. 16 Description of work package 3 and related tasks Tab. 17 Description of work package 4 and related tasks Tab. 18 Description of deliverables and related WPs Tab. 19 WP time and man power allocation budget FIGURE INDEX Fig. 1 the primary mirror in relation to the gravity-weight vector W Fig. 2 simplified geometry of the primary mirror Fig. 3 axial actuator system Fig. 4 disk spring interface Fig. 5 Position of radial support on M1 cell Fig. 6 Position of radial support related to ADC/2Lens device interface on M1 cell Fig. 7 Position of radial support related to axial actuators Fig. 8 Section view of radial support related to M1 mirror Fig. 9 Back view of radial support - M1 mirror Teflon interface Fig. 10 Side view of radial support - M1 cell interface, tilt angle for M1 maintenance Fig. 11 Up view of radial support - M1 mirror Teflon interface, preload system Fig. 12 Up view of radial support - M1 mirror Teflon interface, overall dimensions

5 Pag. 5 of 41 1 Reference/Applicable Documents REF. ID TITLE/CODE DATE AUTHOR COMMENTS REF. 1 Critical Design Review of the VST M1 Cell and M2 Units Summary Report REF. 2 Table list of RIXs ESO CDR package ESO CDR package REF. 3 REF. 4 REF. 5 REF. 6 REF. 7 REF. 8 REF. 9 REF. 10 REF. 11 VST_M1_flotating_technical_note_ Active Optics Mechanics VST-TRE-OAC M1 Actuators Mechanics Kinematics System Dimensioning VST-TRE-OAC XX M1 Cell Finite Element Analysis VST-TRE-OAC doc VST-SPE-OAC pdf VST-MAN-OAC _1.10.doc VST-SPE-OAC doc VST-SPE-OAC doc VST-SPE-OAC doc Tab. 1 Reference Documents M. Brescia Technical Note D. Fierro release 1.1 D. Fierro release 0.1 F. Perrotta release 1.0 G. Marra Optomech. Specifications G. Marra Optical Manual G. Marra Optical specifications G. Marra Image quality budget G. Marra Active Optics technical specifications 5

6 Pag. 6 of 41 2 Abbreviations and Acronyms A & A CDR DRL DWG ESO FEA FEM OAC R&D VST WBS WP Critical Design Review Drawing List Drawing in AutoCAD (Autodesk) Format European Southern Observatory Finite Element Analysis Finite element Modeling Capodimonte Astronomical Observatory Research & Development To Be Defined Very Large Telescope Survey Telescope Work Breakdown Structure Work Package Meaning Tab. 2 Abbreviations and acronyms 6

7 Pag. 7 of 41 3 Introduction This document provides the full description of the engineering investigation and technical solutions regarding the VST M1 Floatation support system. It is part of the documentation package, actually under development by the VST project team, related to post-cdr actions to recover all open items identified during CDR and collected in a list of Review Item Comments, Questions and Discrepancies (referred here as RIXs). In principle the best way to identify open aspects in the M1 floatation support system, is to report a summary of related RIXs, in order to focus globally the points to be fixed, strictly according to ESO requirements. After that, the present document intend to furnish a full description of requirements, specifications, Work Breakdown Structure, man power and time budgets involved in all activities related with the M1 floatation support system. The output of this document will be the list of actions and reference documentation to be provided, in order to close all aspects of the recovery plan regarding the specific subject. The coordination of M1 floatation support system tasks and updating and maintenance of this document is done by M. Brescia. 4 Definition of First of all, a clarification of what it is intended by term M1 Floatation it is necessary, basically, to identify the whole scenario of telescope functionalities and subsystems directly involved and to clarify if the R&D task should be considered as necessary after a deep investigation. One can imagine that a thin meniscus mirror 2.6m in diameter will deform easily when subjected to forces. These forces are due to such factors as changing gravity orientation, active and support forces, environment etc. It is the role of analysis (FEA, FEM) to predict the mirror surface distortions for a given set of boundary conditions. Generally speaking, basic functional requirements for the whole (passive and active) M1 support system are: mirror support: support M1 weight and maintain nominal surface figure over operational zenith angles and environment conditions mirror defining: control the position and orientation of M1 active optics: vary axial forces on M1 to control its surface figure during operation The axial support system is defined as those supports whose resultant force is parallel to the optical axis of the primary mirror. The radial support system is defined as those supports whose resultant force is perpendicular to the optical axis of the primary mirror. These definitions are very important because neither the rear surface nor the outer edge of the primary mirror is normal to the optical axis of the telescope. The basic principle of primary mirror floatation supports is to hold the mirror in the telescope so that the forces of gravity and telescope acceleration do not significantly distort the optical configuration and alignment of the telescope or cause any damage to the primary mirror structure. To avoid bending the mirror, it is necessary to float the blank against the force of gravity as the telescope changes its orientation. To prevent the mirror bending under gravity, its 7

8 Pag. 8 of 41 weight must be carried by many distributed reaction forces. By these conceptual specifications descend a set of functional and system requirements, described in next sections. 8

9 Pag. 9 of 41 5 Summary assessment of the documentation and RIXs for This section reports a summary of RIXs, requirements and comments, submitted by ESO CDR Board to VST project team, specifically addressable to M1 floatation support system. For more information please consult REF. 1 and REF Documents requested (including M1 as subsystem target): a. Project plan and schedule b. M1 Subsystem Requirements derived from VST technical specification c. M1 System Overview d. M1 Cell Overall System Design and Analysis e. Environmental analysis f. M1 MAIT Plan g. M1 AIV Plan h. M1 Maintenance Plan i. Verification Matrix j. Operations Manual k. Maintenance Manual l. Hazard Analysis m. Risk management n. M1 integration procedure within the Cell o. Safety Plan and Reliability Analysis 2. Technical DRDs (referred to sets of still open RIXs) a. Provide OBE and MLE analysis considering the actual anti-turning system at the horizon angle b. Perform an analysis on the most desirable configuration of fixed point and the consequences at M1 system level c. Provide solutions for radial fix points d. Perform complete M1 Cell system FE analysis and environmental qualification tests e. Correct M1 mirror weight and change the order of the mount/dismount M1 f. Certify safety of M1 handling tool according to CE standards and procedure g. Certify position accuracy in centering and rotation of M1 with respect to the Cell during M1 integration h. Provide requirement details and procedure for M1 handling during a coating action sequence 9

10 Pag. 10 of 41 6 VST Strategy, Requirements and Specification Basic concern of M1 support system is to support the mirror for its own weight. Fig. 1 the primary mirror in relation to the gravity-weight vector W In Fig. 1 the primary mirror is shown at some zenith angle. It is also shown the weight gravity vector, W, with its resultant at the geometric center of the mirror. In this scenario, some system of forces must support these weight gravity forces along with any other forces applied to the mirror. Hence, it is possible to assume that forces on the back surface will take care of W cosθ as well as any other forces in the axial direction. The lateral forces, W sin any other force perpendicular to the axis will be taken care of by a radial support system. Main sub-systems related to M1 floatation can be summarized in Tab. 3. θ, along with Sub-unit Code/Notes Type Sub-assembly M1 Cell Mechanical M1 mirror Opto-Mechanical Axial support system Mechanical 13XX Radial support system Mechanical anti-turning system Mechanical M1 handling device Mechanical Tab. 3 Sub-systems related to M1 floatation handling 10

11 Pag. 11 of M1 support system specification By looking at the whole M1 support system design, general issues that must be taken into account are: Optimization of global geometry for axial and radial supports, paying special attention on the influence of the mirror structure on the support geometry Analysis of local deflection and stresses Analysis of the thermal expansion properties of the cell, mirror and support structure Detailed tolerance analysis on the amplitude and locations of the support forces, including potential irregularities in the mirror or support structure Response of the mirror and its support systems to external influences such as telescope acceleration Local and global stress analysis for handling and support load cases Active correction of the primary mirror figure with force actuators The forces applied by the actuators have basically three task to accomplish: floatation of the weight of the mirror while the direction of gravity is changing resistance against external force impulses correction of temporary or permanent figure errors in the mirror surface The forces applied to the axial actuators, F axial, can be expressed in the following form: F = P cosθ + K + K (1) axial mirror oa e where: P cos mirror θ is the axial component due to dead weight of the mirror K is the contribution component for correction of optical aberrations oa K e is the contribution component for correction of environment or operational disturbances Radial actuators do not require forces to correct optical aberrations, giving a resulting expression as: F = P sinθ + K (2) radial mirror e The goal of mirror support is to accomplish all three of the above task simultaneously: astatic floatation, constant force offsets and stiff support against disturbances. 6.2 Strategy for M1 floatation support system The main theoretical requirement that make sense to investigate solutions for a M1 floatation support system is to prevent any displacement in the 3D space of the primary mirror with respect to the cell, due to load distribution changing at different zenith angles, affecting also the telescope optical alignment and representing a potential damage source in case of external disturbing sources or telescope acceleration. In the case of VST, where a M1 active support system is already implemented, the R&D output concerning floatation solutions has, as additional payload, to take into account the effective cost (in all senses) in case of mechanical subsystem modification with respect to the real necessity of these changes. The role of FE analysis, together with optical ray tracing measurements, is crucial in this context to provide information on the real requirement of such a passive support system in the VST M1 cell 1 system. In our 1 In the entire document, the term M1 cell system includes all subsystems included in the M1 cell, i.e. mirror, cell structure and all axial and radial supports 11

12 Pag. 12 of 41 opinion the investigation of such a passive system is anyway required, in order to prevent any kind of mismatch or incompleteness of model and optical analysis that can be arise in respect with the real system. From a technical point of view, the current R&D phase should take, as basic guideline, care of engineering design with respect to optical requirements, considering the M1 cell system in its whole context, in order to prevent the occurrence of too complex solutions. Following sections are intended to be further updated/integrated by specifying solutions coming from R&D tasks (see WBS chapter) Anti-turning system In addition to supporting the mirror against gravity, we must also protect the mirror against unexpected accelerations, that might arise from earthquakes, telescope collisions etc. An already installed solution consists of 8 axial supports linking the cell and mirror at 8 radial pad interface points. Anyway there are alternative solutions under investigation, basically coming from standards widely adopted in telescope projects. Further information will appear in future releases of this document Axial and radial hardpoints The actual VST M1 support system is based on axial and radial active actuators, able to correct mirror surface deformations and in principle able to maintain aligned the mirror within the cell. How well aligned and centered will be known after the FE analysis of the M1 cell system, under development. This is the situation when the control loop is active. This concept is slightly different from standard strategy, where active supports usually are integrated with astatic passive systems, able to balance the dead weight of the mirror in the whole range of zenith angles. So far, some constraints or hardpoints should in principle be provided in the VST, to constrain the six degrees of freedom of mirror (solid body) motion in the cell. The basic role of these hardpoints should keep the mirror aligned with the other parts of the telescope optical system and should provide the needed stiffness to prevent the mirror from translating under the gravity load or moving under some external acceleration. This is particularly required when the active support control system is disabled, occurring between two consecutive active optics corrections. Also, at high zenith angles, when the axial gravity force component, W cosθ, is strongly reduced, the lack of contact between axial actuators and the back surface of the mirror can occur, potentially causing the mirror to slow down in the Y direction, linked to radial contacts only. Finally, the displacement in the X direction should be also taken into account. Fig. 2 simplified geometry of the primary mirror In principle, for maximum resistance to forces bending the mirror over the hardpoints and for system symmetry reasons, the hardpoint supports should be equally spaced around the lateral edge of the mirror and axially spaced at roughly 70% of the radius from the center of the mirror. Obviously, the hardpoints also need to be mounted near stiff locations in the mirror cell structure and avoiding mechanical interference with active support mounting point locations. By summarising this discussion, we can say that, the static equilibrium of the meniscus mirror is maintained by a combination of distribution of axial and radial forces around the mirror. When the mirror is tilted, all forces are 12

13 Pag. 13 of 41 supposed to be controlled, by counter weighting in proportion the cosine of the tilt angle. This result raises an important question: Does a combination of support parameters exist that by itself, that is, without the help of active aberration control, could further reduce the bending distortion to significantly below the maximum mirror displacement calculated by FE and optical analysis? Actually there are under investigation different solutions for hardpoint location, related to provide sufficiently stiff supports in correspondence of the edge of mirror central hole, taking care of any potential vignetting on the image plane. About this idea, it should be considered that this solution was theoretically already studied 2. After a refinement, the conclusion was strengthened that load support at the mirror hole had indeed non advantages in practice. The problem then narrows to the application at the mirror hole, if possible, of forces that do not support weight but simply reduce flexure M1 handling tool and mirror integration in the cell procedure The presence of possible hardpoints in the M1 cell system has an impact also on the optimization of the primary mirror handling tool, actually under R&D revision. The solutions that will be adopted will of course influence the procedure to insert/remove the mirror into/from the cell in safety conditions. There are still under analysis actions on these aspects. 2 G. Schwesinger, Lateral support of very large telescope mirrors by edge forces only, in Journal of Modern Optics, Vol. 38, N 8, , (1991) 13

14 Pag. 14 of Requirements and Specifications for M1 floatation support system This section is dedicated to list optical and mechanical requirements to be taken into account and specifications coming from analysis and measurements, in order to significantly justify the necessity to provide the VST M1 cell system of floatation supports, by integrating the actual active support system, or by replacing some of already implemented solutions in the current M1 support configuration. The quantity and the values of such requirements should come from VST team experts, whose analysis should provide the specific error budget estimation and the specifications to be applied to the identified solutions. By taking this issue in mind, the following are empty or partially filled lists of requirements. People involved (see Work Breakdown Structure sections) is kindly invited to update/modify/integrate them appropriately. All quantities, values, or more generally, all the contributions included here must be provided with all technical information, reference, drawings or whatever, required to clarify, support and explain how they were obtained, which were the system and environmental conditions imposed to obtain them, which methods or instrument used. Otherwise, they will be not considered as acceptable Optical requirements and specification (contents by G. Marra) The main optical requirement for VST from the beginning of the project was to have 80% EE enclosed in 2 at z=0, over the whole field of view of 1.47, and not on average, since it is a wide field telescope. For image quality budget which is usually done in terms of the average rms radius, which is less conservative, in order to obtain the radius of 80% EE, it must be converted and multiplied by the factor The degradation of the optics has been here reported in terms of both image quality parameters (80% EE and rms spot radius) for the worst and average case over the whole field of view. The optical tolerances for VST were made before optics manufacturing considering the maximum degradation of two s. The distance between M2 and M1 was used as compensator. M1 was considered fixed. So the optical tolerances were essentially due to manufacturing errors for mirrors and correctors and to correctors mounting. The present analysis of M1 alignment tolerances is performed minimizing the degradation for image quality for the worst case condition. The analysis on optical requirements and specification for M1 has taken into account the possibility to compensate M1 misalignments with M2 suitable movements. So the maximum tolerances values allowed, keep into account compensation with M2 decentering and tilt. If M2 compensation is not applied, all tolerances value must be divided by two. This analysis has been performed both by mean of a ray tracing tool and analytically. In the final version of the document the curves of M1 misalignment versus 80 % EE diameter in will be reported. As regards performed final analysis regarding optics and optomechanical specifications and as built data see Tab. 4, [REF. 7, REF. 8, REF. 9, REF. 10, REF. 11]. Optical Requirements Value Conditions/Reference Unit M1 maximum decentering tolerance allowed 100 at 0 zenith angle, in X or Y μm direction, for two lens corrector M1 maximum decentering tolerance allowed 100 at 0 zenith angle, in X or Y μm direction, for ADC corrector M1 maximum decentering tolerance allowed 100 at 50 zenith angle, in X or Y μm direction for ADC corrector M1 maximum decentering tolerance allowed 100 at 50 zenith angle, in X or Y μm direction for ADC corrector M2 compensation decentering 150 at 0 zenith angle, respectively in X μm or Y direction, for two lens corrector M2 compensation decentering 150 at 0 and 50 zenith angle, μm 14

15 Pag. 15 of 41 respectively in X or Y direction, for ADC corrector M1 maximum tilt tolerance allowed 0.2 at 0 zenith angle, for two lens corrector around X or Y direction prime with M2 tilt compensation of 0.2 respectively around Y or X axis M1 maximum tilt tolerance allowed 0.2 at 0 zenith angle, for ADC corrector prime around X or Y direction with M2 tilt compensation of 0.2 respectively around X or Y axis M1 maximum tilt tolerance allowed 0.2 at 50 zenith angle, for ADC prime corrector around X or Y direction with M2 tilt compensation of 0.2 respectively around X or Y axis Distance of optical beam from M1 central hole edge 46 Nominal optical configuration mm Distance of optical beam from M1 central hole edge 20 Considering all ranges of mm optomechanical tolerances Space available along M1 diameter at the edge of 20 Nominal mm the optical aperture Tab. 4 Optical requirements 15

16 Pag. 16 of 41 Optical Analysis Value Specification/Conditions/Reference Unit 80% EE diameter worst case 1.66 with 2LENS at 0 z. angle, without decentering in X,Y directions 80% EE diameter worst case 0.35 with 2LENS at 0 z. angle, without decentering in X,Y directions 80% EE diameter average case 1.39 with 2LENS at 0 z. angle, without decentering in X,Y directions 80% EE diameter average case 0.3 with 2LENS at 0 z. angle, without decentering in X,Y directions RMS worst case spot radius 9.79 with 2LENS at 0 z. angle, without decentering in X,Y directions μm Equivalent RMS worst case spot radius on the image with 2LENS at 0 z. angle, without plane decentering in X,Y directions RMS mean spot radius with 2LENS at 0 z. angle, without μm decentering in X,Y directions Equivalent RMS mean spot radius on the image plane with 2LENS at 0 z. angle, without decentering in X,Y directions 80% EE diameter worst case 1.69 with 2LENS at 0 z. angle, applying 100 μm of decentering in X ory direction to M1 and 150 μm decentering compensation respectively in X or Y direction to M2 80% EE diameter worst case with 2LENS at 0 z. angle, applying 100 μm of decentering in X or Y direction to M1 and 150 μm decentering compensation respectively in X or Y direction to M2 80% EE diameter average case 1.37 with 2LENS at 0 z. angle, applying 100 μm of decentering in X or Y direction to M1 and 150 μm decentering compensation resepectively in X or Y direction to M2 80% EE diameter average case with 2LENS at 0 z. angle, applying 100 μm of decentering in X or Y direction to M1 and 150 μm decentering compensation respectively in X or Y direction to M2 RMS worst case spot radius 10 with 2LENS at 0 z. angle, applying 100 μm of decentering in X or Y direction and 150 μm decentering compensation in X or Y direction to M2 μm Equivalent RMS worst case spot radius on the image plane with 2LENS at 0 z. angle, applying 100 μm of decentering in X or Y direction to M1 and 150 μm decentering compensation respectivley in X or Y direction to M2 RMS mean spot radius with 2LENS at 0 z. angle, applying μm 16

17 Pag. 17 of μm of decentering in X or Y direction to M1 and 150 μm decentering compensation respectively in X or Y direction to M2 Equivalent RMS mean spot radius on the image plane with 2LENS at 0 z. angle, applying 100 μm of decentering in X or Y to M1 and 150 μm decentering compensation respectively in X ory direction to M2 80% EE diameter worst case 1.93 with 2LENS at 0 z. angle, applying 100 μm of decentering in X or Y direction to M1 without compensation in X or Y direction to M2 RMS worst case spot radius with 2LENS at 0 z. angle, applying 100 μm of decentering in X or Y direction to M1 without compensation in X or Y direction to M2 Equivalent RMS worst case spot radius on the image plane 0.16 with 2LENS at 0 z. angle, applying 100 μm of decentering in X or Y direction to M1 without compensation in X or Y direction to M2 80% EE diameter worst case 1.76 with 2LENS at 0 z. angle, applying 0.2 of tilt in Y direction without M2 compensation 80% EE diameter worst case 1.64 with 2LENS at 0 z. angle, applying 0.2 prime of tilt in Y direction with M2 tilt of 0.33 prime compensation RMS worst case spot radius with 2LENS at 0 z. angle, applying 0.2 prime of tilt in Y direction without M2 compensation Equivalent RMS worst case spot radius on the image plane with 2LENS at 0 z. angle, applying 0.2 prime of tilt in Y direction without M2 compensation 80% EE diameter worst case 1.94 with 2LENS at 0 z. angle, applying 0.2 prime of tilt in X direction without M2 compensation 80% EE diameter worst case 1.7 with 2LENS at 0 z. angle, applying 0.2 prime of tilt in X direction with M2 tilt of 0.33 prime compensation RMS worst case spot radius 10 with 2LENS at 0 z. angle, applying 0.2 prime of tilt in X direction with M2 tilt of 0.33 prime compensation RMS worst case spot radius with 2LENS at 0 z. angle, applying 0.2 prime of tilt in X direction with M2 tilt of 0.33 prime compensation 80% EE diameter worst case 1.93 with ADC at 0 z. angle, without decentering in X,Y directions 80% EE diameter worst case 0.41 with ADC at 0 z. angle, without decentering in X,Y directions RMS worst case spot radius 11.4 with ADC at 0 z. angle, without decentering in X,Y directions μm μm μm μm 17

18 Pag. 18 of 41 Equivalent RMS worst case spot radius on the image plane with ADC at 0 z. angle, without decentering in X,Y directions RMS mean spot radius with ADC at 0 z. angle, without decentering in X,Y directions Equivalent RMS mean spot radius on the image plane with ADC at 0 z. angle, without decentering in X,Y directions 80% EE diameter worst case 2.2 with ADC at 0 z. angle, applying direction without M2 compensation 80% EE diameter worst case with ADC at 0 z. angle, applying direction without M2 compensation 80% EE diameter worst case with ADC at 0 z. angle, applying direction without M2 compensation RMS worst case spot radius with ADC at 0 z. angle, applying direction without M2 compensation Equivalent RMS worst case spot radius on the image plane with ADC at 0 z. angle, applying direction without M2 compensation 80% EE diameter average 2 with ADC at 0 z. angle, applying direction without M2 compensation RMS mean spot radius 11.8 with ADC at 0 z. angle, applying direction without M2 compensation Equivalent RMS mean spot radius on the image plane with ADC at 0 z. angle applying direction without M2 compensation 80% EE diameter worst case 2 with ADC at 0 z. angle, applying direction with M2 compensation of 150 micron decentering along y 80% EE diameter worst case 0.4 with ADC at 0 z. angle, applying direction with M2 compensation of 150 micron decentering along y RMS worst case spot radius with ADC at 0 z. angle, applying direction with M2 compensation of 150 micron decentering along y RMS worst case spot radius 0.16 with ADC at 0 z. angle, applying direction with M2 compensation of 150 micron decentering along y 80% EE diameter average case 1.97 with ADC at 0 z. angle, applying direction with M2 compensation of 150 micron decentering along y 80% EE diameter average case 0.42 with ADC at 0 z. angle, applying direction with M2 compensation of μm μm μm μm 18

19 Pag. 19 of micron decentering along y RMS mean spot radius with ADC at 0 z. angle, applying direction with M2 compensation of 150 micron decentering along y Equivalent RMS mean spot radius on the image plane with ADC at 0 z. angle, applying direction with M2 compensation of 150 micron decentering along y 80% EE diameter worst case 2 with ADC at 0 z. angle, applying 100 μm of decentering in X direction without M2 compensation 80% EE diameter worst case 1.96 with ADC at 0 z. angle, applying 100 μm of decentering in X direction with M2 compensation of 150 micron decentering along x 80% EE diameter worst case 1.98 with ADC at 0 z. angle, applying 0.2 of tilt around Y axis without M2 compensation 80% EE diameter worst case with ADC at 0 z. angle, applying 0.2 of tilt around Y axis without M2 compensation 80% EE diameter worst case 1.93 with ADC at 0 z. angle, applying 0.2 of tilt around Y axis with M2 compensation of 0.2 around y axis 80% EE diameter worst case 2.14 with ADC at 50 z. angle, without decentering in X,Y directions 80% EE diameter worst case 0.46 with ADC at 50 z. angle, without decentering in X,Y directions RMS worst case spot radius 12.5 with ADC at 50 z. angle, without decentering in X,Y directions Equivalent RMS worst case spot radius on the image plane with ADC at 50 z. angle, without decentering in X,Y directions 80% EE diameter worst case 2.5 with ADC at 50 z. angle, applying direction 80% EE diameter worst case 2.3 with ADC at 50 z. angle, applying 100 μm of decentering in X direction 80% EE diameter worst case 2.1 with ADC at 50 z. angle, applying direction and compensating with M2 decentering of 150 micron along y 80% EE diameter worst case 2.2 with ADC at 50 z. angle, applying 100 μm of decentering in X direction and compensating with M2 decentering of 150 micron along X 80% EE diameter worst case 2.2 with ADC at 50 z. angle, applying 0.2 of tilt around Y direction without M2 compensation RMS worst case spot radius 12.3 with ADC at 50 z. angle, applying μm μm μm 19

20 Pag. 20 of 41 direction compensating with M2 decentering of 150 μm RMS worst case spot radius 0.17 with ADC at 50 z. angle, applying direction compensating with M2 decentering of 150 μm RMS mean spot radius 11.8 with ADC at 50 z. angle, applying direction compensating with M2 decentering of 150 μm Equivalent RMS mean spot radius on the image plane with ADC at 50 z. angle, applying direction compensating with M2 decentering of 150 μm RMS mean spot radius with ADC at 50 z. angle, applying 100 μm of decentering in X direction compensating with M2 decentering of 150 μm along X Equivalent RMS mean spot radius on the image plane with ADC at 50 z. angle, applying 100 μm of decentering in X direction compensating with M2 decentering of 150 μm along X 80% EE diameter worst case 2.2 with ADC at 50 z. angle, applying 0.2 of tilt around Y direction without M2 compensation 80% EE diameter worst case 2.1 with ADC at 50 z. angle, applying 0.2 of tilt around Y direction with M2 compensation of 0.2 of tilt around y. RMS worst case spot radius with ADC at 50 z. angle, applying 0.2 of tilt around Y direction with M2 compensation of 0.2 of tilt around y. 80% EE diameter worst case 2.4 with ADC at 50 z. angle, applying 0.2 of tilt around X direction without M2 compensation 80% EE diameter worst case 2.1 with ADC at 50 z. angle, applying 0.2 of tilt around X direction with M2 compensation of 0.2 of tilt around X RMS worst case spot radius with ADC at 50 z. angle, applying 0.2 of tilt around X direction with M2 compensation of 0.2 of tilt around X. μm μm μm μm Tab. 5 Optical Analysis Specifications 20

21 Pag. 21 of FE analysis specifications and results (contents by F. Perrotta) This section has to be considered open, in the sense that VST team people in charge of these tasks must be fill it of all contents, information, values covering all FE analysis specification and result aspects involved in the M1 floatation support system. On May, , the preliminary version of M1 cell FEM and FEA document has been released. All details about its contents are reported in REF. 6. This analysis determined M1 cell stress field and deflections along telescope reference system X and Y axes when subject to its proper weight, mirror weight, instrumentation weight and actuators weight, when supported by flexion bars considered fixed in space at their interface with centrepiece, which has not been modelled. The integration of M1 cell FEA, taking into account also the ADC/2Lens device, linked to the backside of cell, will be further realized in the next weeks. Currently, the FEM of M1 mirror is under development. It will include modelling of axial, radial and anti-turning device solutions, currently under R&D phase. 21

22 Pag. 22 of Mechanical requirements and specification This section has to be considered open, in the sense that VST team people in charge of these tasks must be fill it of all contents, information, values covering all mechanical design aspects involved in the M1 floatation support system Axial Supports (contents by D. Fierro) The solution for axial fixed supports is oriented towards the conversion of three actual active actuators, (Fig. 3), Fig. 3 axial actuator system positioned in the third ring (from the center of the mirror), by modifying the height of spring housing (Fig. 4). In practice, by reducing the height and by locking the cover it is possible to impose a pre-calculated preload to the system. This induces a compression to the springs through the load cell interface. The actuator will be then result absolutely stiff up to a reached push equal to the imposed preload. After that it will be result elastic with the same elasticity of the other active actuators. Of course, the preload will require a correct evaluation as a function of maximum load variation on the single actuator in disabled control system conditions and depending on mirror safety conditions. The spring stiffness is 110 kg/mm, hence a lowering of 0.7mm is considered useful to a preload of 80kg. 22

23 Pag. 23 of 41 Fig. 4 disk spring interface For more information and/or specification on actuators, please refer to REF. 4 and REF Radial Supports (contents by O. Caputi) The Radial support system proposed for M1 flotation system is composed of the following systems. 1. A stiff support general support is centered on M1 cell cylindrical hole by means of a dedicated interface and n 4 M12 screw connection. This support provides for an horizontal axis of rotation which is the interface for the pivoting support. 2. The Pivoting Support is a stiff structure with a V shape that embraces the relative axial actuator placed in the cardinal point of the inner ring of the M1 cell axial actuator interface. The V shape allows the maintenance of the relative axial actuator. It is interfaced with the General support by means of a Ø20 axis and with the M1 cell By means of n 2 M16 screw connections. These last screws are preloaded by means of compression springs so that, when the screws are untied, the Pivoting Support rotate to a maximum range of 5. This angle allows the mounting/dismounting procedure for M1 mirror, by only unscrewing these n 2 screws (for n 4 Radial Supports). 3. The Radial Preloading Slide allows radial small adjustments for the M1 Mirror radial system in order to reach the correct M1 mirror positioning. N 2 linear guides are connected on the upper surface of the Pivoting Support. Acting on the N 2 M12 tightening screws the Radial Preloading Slide can be placed so that the correct preload on the M1 mirror can be achieved. A Radial Activation Load system is provided so that Belleville spring are constantly preloaded to guarantee total stiffness unless a 500N load is reached. After that value of load the system reacts with an overall rigidity of 10000Kg/mm. 4. The vertical pivoting axis allows the correct interface between the M1 mirror cylindrical face of the hole and the interface cylindrical sector of the preloader. The interface with the M1 mirror is provided with a 3mm Teflon spacer. The overall compression elongation of the Teflon spacer under the total weight of the mirror at 90 is within 0.006mm. This ca be explained by the following formula: 23

24 Pag. 24 of 41 L N L 3 Δ = = 0.67 = 0. mm A E Where: N/A = 0.67 N/mm 2 L = 3mm E = 350 N/mm 2 Requirements Value Conditions/ Unit Reference Radial Force Y (due to mirror weight) N Radial Constraint Resistance Pressure Y (due to mirror weight) N/mm 2 Preloading Sector surface area mm 2 Elongation of Teflon spacer under compression of 20000N mm Radial Force X (unbalancing force)? Earthquake? 0 N Radial Activation Load X 500 Every angle N Radial Activation Load Y 500 Every angle N Preloading Pressure N/mm 2 Tilt angle for M1 mirror maintenance 5 0 deg Tab. 6 Mechanical requirements for radial support system Analysis Value Specification/Conditions/Reference Unit Tab. 7 Mechanical analysis specification for radial support system () 24

25 Pag. 25 of 41 Fig. 5 Position of radial support on M1 cell Fig. 6 Position of radial support related to ADC/2Lens device interface on M1 cell 25

26 Pag. 26 of 41 Fig. 7 Position of radial support related to axial actuators Fig. 8 Section view of radial support related to M1 mirror 26

27 Pag. 27 of 41 Fig. 9 Back view of radial support - M1 mirror Teflon interface Fig. 10 Side view of radial support - M1 cell interface, tilt angle for M1 maintenance 27

28 Pag. 28 of 41 Fig. 11 Up view of radial support - M1 mirror Teflon interface, preload system Fig. 12 Up view of radial support - M1 mirror Teflon interface, overall dimensions 28

29 Pag. 29 of Anti-turning System (contents by L. Ferragina) TO BE COMPLETED Requirements Value Conditions/Reference Unit Tab. 8 Mechanical requirements for anti-turning system Analysis Value Specification/Conditions/Reference Unit Tab. 9 Mechanical Analysis Specifications for anti-turning system 29

30 Pag. 30 of M1 Handling System (contents by L. Ferragina) TO BE COMPLETED Requirements Value Conditions/Reference Unit Tab. 10 Mechanical requirements for M1 handling system Analysis Value Specification/Conditions/Reference Unit Tab. 11 Mechanical Analysis Specifications for M1 handling system 30

31 Pag. 31 of 41 7 M1 Floatation support system Work Breakdown Structure By concerning the M1 floatation support system, the following is the related WBS. M1 Floatation support system WP 1 WP 2 WP 3 WP 4 Axial support system Radial support system Anti-turning system M1 handling system Tab. 12 Work Breakdown Structure Each block, or WP, of the WBS includes a specific group of tasks/actions, whose output will be a documentation package related to specific activities. WP - DESCRIPTION People involved WP- 1 Axial Support System Task 1. 1 Optical requirements & specifications Task 1. 2 Mechanical requirements & specifications Task 1. 3 Error Budget Task 1. 4 Preliminary Design & feasibility study Task 1. 5 Design & Procurement Task 1. 6 Realization Task 1. 7 Verification and test Task 1. 8 Maintenance Plan Task 1. 9 FEA specifications and results G. Marra D. Fierro, F. Perrotta P. Schipani D. Fierro, O. Caputi D. Fierro D. Fierro, O. Caputi, F. Perrotta O. Caputi F. Perrotta WP- 2 Radial Support System Task 2. 1 Optical requirements & specifications Task 2. 2 Mechanical requirements & specifications Task 2. 3 Error Budget Task 2. 4 Preliminary Design & feasibility study Task 2. 5 Design & Procurement Task 2. 6 Realization Task 2. 7 Verification and test Task 2. 8 Maintenance Plan Task 2. 9 FEA specifications and results G. Marra O. Caputi, L. Ferragina P. Schipani D. Fierro, O. Caputi O. Caputi D. Fierro, O. Caputi, F. Perrotta O. Caputi F. Perrotta WP- 3 M1 Anti-turning System Task 3. 1 Mechanical requirements & specifications Task 3. 2 Preliminary Design, FEA & feasibility study L. Ferragina L. Ferragina, F. Perrotta 31

32 Pag. 32 of 41 Task 3. 3 Design & Procurement Task 3. 4 Realization Task 3. 5 Verification and test Task 3. 6 Maintenance Plan L. Ferragina L. Ferragina, D. Fierro, O. Caputi, F. Perrotta L. Ferragina WP- 4 M1 Handling System Task 4. 1 Mechanical requirements & specifications Task 4. 2 Revision, FEA, and feasibility study Task 4. 3 M1 Handling IN/OUT (cell and truck) procedure analysis Task 4. 4 Design and Procurement Task 4. 5 Realization Task 4. 6 Verification and test Task 4. 7 Maintenance Plan L. Ferragina L. Ferragina, F. Perrotta L. Ferragina, D. Fierro, F. Perrotta L. Ferragina L. Ferragina, D. Fierro, O. Caputi, F. Perrotta L. Ferragina Tab. 13 Work Breakdown Structure and Work Packages 7.1 Description of Work Packages Title WP id Main reference task Main People involved Main Task Consultant Task Manager Description WP Task 1.1 Task 1.2 Task 1.3 Task 1.4 Task 1.5 Task 1.6 Task 1.7 Task 1. 8 Task 1. 9 Axial Support System WP-1 D. Fierro, O. Caputi G. Marra, F. Perrotta M. Brescia The WP-1 main target is the deep analysis of M1 cell system requirements (optical and mechanical) in order to verify the real necessity of an axial floatation support for the primary mirror and in case, to implement it to define and analyse all optical requirements and specifications related to M1 cell system, (in particular, tolerances, performances and room calculations) to verify and support technical requirement and the feasibility study for axial floatation system to define all requirements and specifications (stiffness, loads, force distribution, spring features, rooms, materials, etc.) useful to better analyse and fix the axial floatation problem to verify the feasibility of solutions proposed in terms of degradation of performances potentially affecting the whole telescope system By taking into account outputs coming from tasks 1.1 and 1.2, with a feedback from task 1.3, it will be possible to perform an optimization loop of feasible solutions analysed and proposed Once a solution is found, next step is to provide a final complete design and procurement of realization facilities and companies During the realization, a continuous check of assigned companies activities should be guaranteed by task people, in order to maintain the time schedule and to verify and adjust all work in progress After realization, it is naturally required a verification and test of the implemented system, but before, a verification and test plan and procedure should be provided All aspects related with maintenance plan and procedures should be provided FE analysis to support and verify technical solutions proposed 32

33 Pag. 33 of 41 Inputs Documentation Starting Event Outputs Results Deliverables Time Schedule WP-1-Del.1 support documents for optical requirements & specifications WP-1-Del.2 support documents for mechanical requirements & specifications meeting after CDR Kick Off (T0) April 10, 2007 duration M1 axial floatation system complete solution WP-1-Del.3 support documents and drawings for feasibility study and technical proposal WP-1-Del.4 support documents and drawings for implementation WP-1-Del.5 integration procedure WP-1-Del.6 verification plan document WP-1-Del.7 test procedure WP-1-Del.8 test reports WP-1-Del.9 maintenance plan document WP-1-Del.10 maintenance procedure 4 months End July 31, 2007 Task 1.1 end May 18, 2007 Task 1.2 end May 25, 2007 Task 1.3 end Task 1.4 end May 8, 2007 Task 1.5 end Task 1.6 end Task 1.7 end Task 1. 8 end Task 1. 9 end May 18, 2007 Tab. 14 Description of Work Package 1 and related tasks 33

34 Pag. 34 of 41 Title WP id WP- 2 Main reference task Main People involved Main Task Consultant Task Manager Description WP Task 2.1 Task 2.2 Task 2.3 Task 2.4 Task 2.5 Task 2.6 Task 2.7 Task 2.8 Task 2.9 Inputs Documentation Starting Event Outputs Results Deliverables Time Schedule Radial Support System D. Fierro, O. Caputi G. Marra, F. Perrotta, L. Ferragina M. Brescia The WP-2 main target is the deep analysis of M1 cell system requirements (optical and mechanical) in order to verify the real necessity of a radial floatation support for the primary mirror and in case, to implement it to define and analyse all optical requirements and specifications related to M1 cell system, (in particular, tolerances, performances and room calculations) to verify and support technical requirement and the feasibility study for radial floatation system to define all requirements and specifications (stiffness, loads, force distribution, spring features, rooms, materials, etc.) useful to better analyse and fix the radial floatation problem to verify the feasibility of solutions proposed in terms of degradation of performances potentially affecting the whole telescope system By taking into account outputs coming from tasks 2.1 and 2.2, with a feedback from task 2.3, it will be possible to perform an optimization loop of feasible solutions analysed and proposed Once a solution is found, next step is to provide a final complete design and procurement of realization facilities and companies During the realization, a continuous check of assigned companies activities should be guaranteed by task people, in order to maintain the time schedule and to verify and adjust all work in progress After realization, it is naturally required a verification and test of the implemented system, but before, a verification and test plan and procedure should be provided All aspects related with maintenance plan and procedures should be provided FE analysis to support and verify technical solutions proposed WP-2-Del.1 support documents for optical requirements & specifications WP-2-Del.2 support documents for mechanical requirements & specifications meeting after CDR Kick Off (T0) April 10, 2007 duration M1 radial floatation system complete solution WP-2-Del.3 support documents and drawings for feasibility study and technical proposal WP-2-Del.4 support documents and drawings for implementation WP-2-Del.5 integration procedure WP-2-Del.6 verification plan document WP-2-Del.7 test procedure WP-2-Del.8 test reports WP-2-Del.9 maintenance plan document WP-2-Del.10 maintenance procedure 4 months End July 31, 2007 Task 2.1 end May 18, 2007 Task 2.2 end May 8,

35 Pag. 35 of 41 Task 2.3 end Task 2.4 end May 8, 2007 Task 2.5 end Task 2.6 end Task 2.7 end Task 2.8 end Task 2.9 end May 18, 2007 Tab. 15 Description of work package 2 and related tasks Title WP id Main reference task Main People involved Main Task Consultant Task Manager Description WP Task 3.1 Task 3.2 Task 3.3 Task 3.4 Task 3.5 Task 3.6 Inputs Documentation Starting Event Outputs Results Deliverables Time Schedule M1 Anti-turning System WP-3 L. Ferragina D. Fierro, O. Caputi, F. Perrotta M. Brescia The WP-3 main target is the deep analysis of the problem to provide a safely protection of M1 in case of earthquake or any other source of telescope acceleration. Main target is to compare the actual solution implemented with standard solution adopted on telescopes. to define all requirements and specifications (stiffness, loads, force distribution, spring features, rooms, materials, etc.) useful to better analyse and compare the solutions By taking into account outputs coming from task 3.1, it will be possible to perform an optimization loop of feasible solutions analysed and proposed Once a solution is found, next step is to provide a final complete design and procurement of realization facilities and companies (if different in respect of already implemented solution) During the realization, a continuous check of assigned companies activities should be guaranteed by task people, in order to maintain the time schedule and to verify and adjust all work in progress After realization, it is naturally required a verification and test of the implemented system, but before, a verification and test plan and procedure should be provided All aspects related with maintenance plan and procedures should be provided WP-3-Del. 1 support documents for mechanical requirements & specifications meeting after CDR M1 anti-turning system complete solution WP-3-Del. 2 support documents and drawings for feasibility study and technical proposal WP-3-Del. 3 support documents and drawings for implementation WP-3-Del. 4 integration procedure WP-3-Del. 5 verification plan document WP-3-Del. 6 test procedure WP-3-Del. 7 test reports WP-3-Del. 8 maintenance plan document WP-3-Del. 9 maintenance procedure 35