Mechanical Overview

1
Mechanical Overview
WBS 1.5 Opto-Mechanical System Andy Stefanik -
Fermilab
2
Optical Element Positioning Requirements

• Corrector optical design 2605-v3.
• Sensitivity analysis.

C1
Filters Shutter
C2
C3
C4
C5
Packaged CCDs
3
Cells and CCD Focal Plane Support

• Conceptual cells for C1, C2, C3 and C4 by B.
  Bigelow _at_ UM.
• Conceptual cell for C5 and focal plane support by
  H. Cease _at_ Fermilab.

Focal plane
C1 cell
C4 cell
Bipods
Forward ring
C2 C3 cell
C5 cell ring (blue) retainer (yellow)
All cells bolt to the barrel. Forward ring welds
to the camera vessel shell.
4
Cells and CCD Focal Plane Support

• Cells for C1, C2, C3 and C4 (WBS 1.4.6) Designed
  and provided by University College London (UCL),
  Peter Doel.
• Lenses installed in cells at UCL.
• Cells installed in barrel at UCL.
• C5 cell (WBS 1.4.7) and focal plane support (WBS
  1.5.2.4) Designed and provided by Fermilab,
  Herman Cease. Breakout Session 2.
• C1 (current model) 140 Kg (309 Lbs), 940 mm OD,
  237.2 mm overall axial length.
• C2 (current model) 72 Kg (159 Lbs), 658 mm OD,
  158.7 mm overall axial length.
• C3 (current model) 41 Kg (90 Lbs), 610 mm OD,
  76.8 mm overall axial length.
• C4 (current model) 40 Kg (88 Lbs), 578 mm OD,
  127.8 mm overall axial length.
• C5 (current model) 24 Kg (60 Lbs), 508 mm OD,
  83.3 mm overall axial length.
• Filter (current model) 578 mm OD.
• Focal plane Cast aluminum tooling plate.
• C5 cell Stainless steel ring, PVC retainer.
• Bipod leg Titanium 6AL4V Grade 5.
• Forward ring Stainless steel.

5
Multi-CCD Test Vessel (WBS 1.5.2.1)

Monsoon crate
C4
C5
6
Prime Focus Camera

• Prime focus camera (WBS 1.5.2.3 and 1.5.2.5)
  Designed and provided by Fermilab, Herman Cease.
  Breakout Session 2.
• Multi-CCD test vessel (WBS 1.5.2.1) is the
  prototype camera. It arrived at Fermilab on July
  14, 2006. Herman Cease. Breakout Session 2.
• Material of construction Electropolished
  stainless steel.
• Weight empty 205 Kg (450 lbs).
• Weight fully equipped (includes C5 and its cell)
  590 Kg (1300 lbs).
• Shell OD 609.6 mm.
• Overall length 764.4 mm.
• Operates at 10-6 torr.
• Bolts to the C5 cell.
• Cryogenic cooling of the CCDs in the multi-CCD
  test vessel Pool boiling liquid nitrogen copper
  straps connect the focal plane to the copper heat
  sink. Designed for horizontal use only.
• Cryogenic cooling method of the CCDs in the prime
  focus camera TBD.

7
Multi-CCD Test Vessel

C4
8
Multi-CCD Test Vessel at UCEC

9
Barrel and Prime Focus Camera

Opening for filter changer and shutter. Shutter
is installed directly in front of C4.
Prime Focus Camera
Stray light baffles (not shown)
10
Barrel and Prime Focus Camera

Prime Focus Camera
Cone
Body
11
Barrel

• Barrel (WBS 1.5.4.1) Designed and provided by
  Fermilab, Andy Stefanik.
• Material alternatives Plated/coated carbon
  steel. Electropolished 304L SS.
• Weight 820 Kg (1800 lbs). Overall length 1505.6
  mm.
• Outside dimensions 1030 mm at C1, 1016 x 1016 mm
  at opening for filter changer and shutter, 865
  mm flange OD at camera vessel.
• Opening for filter changer and shutter 233 x 763
  mm.
• Cone and body are separate weldments that are
  stress relieved before machining. Cone final
  machining takes place after it is bolted and
  pinned to the body.
• Cone, body and camera vessel bolt together.
• Two concepts being considered Round body and
  square body.
• Drawings for round body concept have been
  prepared to get a budget cost estimate and to
  check feasibility of the fabrication tolerances.
• Longitudinal (axial) fabrication tolerance /-25
  microns. (alternative cell spacer)
• Radial (decenter) fabrication tolerance /-25
  microns. (alternative locating pins)
• Deflection requirement 25 microns maximum droop
  at the CCDs and at C1. 6 arcseconds tilt at the
  CCDs and 5 arcseconds tilt at C1.
• The barrel carries a cantilevered load from each
  of its ends to the hexapod.
• Cost drivers Deflection requirement, machining
  tolerances and material choices.

12
Hexapod

Hexapod with 6 actuators
Payload center of gravity offset 136 mm.
13
Hexapod Actuator Example

Competition Sensitive
14
Hexapod

• Hexapod (WBS 1.5.6.2) Specified and provided by
  Fermilab, French Leger. Breakout Session 4.
• Specification Range of travel for each of the 6
  degrees of freedom, repeatability, payload,
  payload offset, geometry constraints, attachment
  constraints, control system, power supply.
• Minimum adjustments are specified in DES Document
  20-v9, Science and Technical Requirements.
  Stephen Kent. Breakout Session 4.
• A budget quotation for a turnkey system has been
  obtained from an experienced supplier.
• Payload 2275 Kg (5000 Lbs)
• Extra weight might have to added to the C1 end of
  the barrel to minimize the payload offset.

15
Filter Changer and Shutter

Light-tight, dust-tight cover
16
Filter Changer, Shutter Stray Light Baffles

• Filter changer (WBS 1.5.5.1) Designed and
  provided by University of Michigan, Bruce
  Bigelow.
• Filter changer requirements are being developed.
• Four (4) DES filters.
• Two (2) guest filters.
• Filter diameter 570 mm.
• Filter thickness TBD. Current estimate is 10 to
  30 mm.
• Shutter (WBS 1.5.5.2) Provided by University of
  Michigan, Bruce Bigelow.
• Shutter Designed and built by Bonn University. A
  budget quotation has been obtained.
• Stray light baffles (WBS 1.5.4.3) Designed and
  provided by University of Michigan, Bruce
  Bigelow.

17
Filter Changer

18
Example of a Bonn shutter (PanSTARRS)

PanSTARRS (approximate) Length 1500 mm Width
680 mm Depth 50 mm Shutter aperture 480 x 480
mm DECam Length 2060 mm Width 760 mm Depth 56
mm Shutter aperture 570 mm diameter
19
Prime Focus Cage

840 mm offset from cage flip axis to center of
gravity for DECam and F8
F8 Mirror
20
Prime Focus Cage

• Prime Focus Cage (WBS 1.5.6.1) Redesigned and
  provided by Fermilab, French Leger.
• Discard existing pedestal.
• Reuse existing components F8, petal covers,
  mounting rings and fins.
• Redesign rails to anchor the hexapod.
• Extra weight must be added to the C1 end of the
  prime focus cage to balance the weight about the
  flip axis.
• Estimated weight of equipment for DECam 2700 Kg
  (6000 Lbs).

21
Prime Focus Cage

22
Taking Data in the Blanco

23
Auxiliary Systems

• New C1 cover (WBS 1.5.4.2) A recent suggestion
  but probably not needed.
• Camera calibration/response system (WBS 1.5.9.1)
  Future work.
• Cloud camera (WBS 1.5.9.2) Future work.
• Guide system (WBS 1.5.9.3) Future work.

24
Telescope Finite Element Modeling

WBS 1.5.8
25
Process Systems

• Prime focus camera cooling (WBS 1.5.3.1)
  Designed and provided by Fermilab, Richard
  Schmitt. Several methods are being considered.
  Breakout Session 4.
• Electronic crate cooling (WBS 1.5.3.2)
  Water-alcohol coolant. Future work.
• Barrel dry gas purge (WBS 1.5.3.3) Dry nitrogen
  gas is currently available in the prime focus
  cage. The existing system must be evaluated and
  modified or replaced if necessary. The existing
  corrector is not purged but dry nitrogen is used
  to keep the dewar window from fogging up.
• Cage dry air Dry air is currently available in
  the prime focus cage. The existing system must be
  evaluated and modified or replaced if necessary.
  An air supply reservoir might have to be added.
• Cage temperature monitoring (WBS 1.5.3.4) Future
  work.
• I/O system (WBS 1.5.3.5 1.5.3.13) Future work.
  Designed and provided by Fermilab, Herman Cease.

26
Camera Cooling
7-14-06 - RLS
27
Camera Cooling Heat Loads

• Focal Plate Supports 10 Watts
• CCDs 20 Watts
• Wiring and Cables 25 Watts
• Radiation heat load 70 Watts
• Add safety factor
• Total heat load 200 Watts

7-14-06 - RLS
28
Component Testing

• All components will be fully tested by the
  responsible institution before shipment to CTIO
  or to the telescope simulator at Fermilab.
• Telescope simulator (WBS 1.5.7) Designed and
  provided by Fermilab, Andy Stefanik.
• Primary purpose of the telescope simulator is to
  load test the hexapod and to flip test the cable
  runs and process lines at all operating
  positions. Secondary purpose is to perform
  additional testing of other components at all
  operating positions.
• Assure fabrication and functional requirements
  are met.
• Typical mechanical testing of components and
  systems alignment, dimensional check,
  deflection, assembly repeatability, motion
  repeatability, thermal cycle, thermal shock,
  mechanical shock, motion cycle, operating
  position, control, failure modes, vibration, loss
  of vacuum, rate-of-rise test.
• A 360 flipping cart (WBS 1.5.2.2) is planned to
  test prime focus camera operation in various
  positions. The cart will be designed and provided
  by UCEC.

29
WBS 1.5 Mechanical Integration

• Fermilab Prime focus camera, barrel, telescope
  simulator, process systems, auxiliary systems.
• Fermilab SDSS telescope, Apache Point
  Observatory, NM Hexapod, prime focus cage.
• CTIO Design, installation, operation,
  maintenance requirements for the new components.
  Telescope details.
• NOAO Telescope drawings.
• UCEC Multi-CCD test vessel fabrication, 360
  flipping cart.
• University of Michigan Filter-changer, shutter,
  stray light baffles.
• UCL Cells.

30
WBS 1.5 Cost Schedule Summary

Costs are unburdened and unescalated.
31
WBS 1.5.10 Opto-Mechanical Systems Milestones

• 1.5.10.3 L3 Multi-CCD test vessel ready for CCD
  installation Oct 06
• 1.5.10.4 L3 Design review for cage and F8 plans
  complete Jun 07
• 1.5.10.6 L4 360 test of cooling system
  complete Aug 07
• 1.5.10.7 L3 Design review of focal plate
  complete Nov 07
• 1.5.10.1 L3 Design review of camera and cooling
  complete Dec 07
• 1.5.10.2 L2 Design review of camera and cooling
  complete Dec 07
• 1.5.10.5 L4 Camera cooling plant review
  complete Jan 08
• 1.5.10.11 L3 Shutter and filter delivered to
  Fermilab Oct 08
• 1.5.10.9 L3 Camera vessel ready for
  installation on barrel Nov 08
• 1.5.10.8 L3 Cage ready for telescope
  simulator Apr 09
• 1.5.10.12 L3 Barrel ready for telescope
  simulator May 09
• 1.5.10.13 L3 All process input/output systems
  complete May 09
• 1.5.10.10 L3 Electronic crate cooling system
  complete Jun 09
• 1.5.10.14 L4 Telescope simulator tests
  complete Sep 09
• 1.5.10.15 L2 Camera testing complete Sep 09