Hires CCD Upgrade


Dewar Mechanical Design Review – 7/17/02



Agenda – meeting notes


A         Dewar Vessel – 3D Inventor model

1                   CCD & backplane

a.      Back plane material to be Invar

b.      Locating delrin pins to be removed

c.      center CCD assembly will be the position reference, back plane thru holes to be tighter for precision placement, shooting for tolerance of 50 mm

d.      need to develop a back plane interface to the CCD lab tooling and the stand/holder that allows flipping over entire assembly

e.      flexicables from Luppino are late; Dave to contact Gerry to see if this can be expedited; we’ll ask for the moly bases to be shipped separately since we can start working on these

f.        clamps for silver straps should use substantial screws and plenty of thread engagement

g.      move kinematic points further from mosaic

2                   Support spider

a.      Attachment ring could be dispensed with and assembly could be screwed directly to rear lid

b.      Dynamic analysis needs to confirm adequate stiffness and natural frequencies above 20 Hz

c.      Attachment to CCD assembly should have countersink for delrin spacers so that they stay in place during the assy process

3                   Dewar housing

a.      Getter is a must; needed (as a minimum) to remove moisture from all the components; can be quite small; Zeolite most likely will be used

b.      Welding to coldfinger pipe very viable; would be easier to fabricate; a design will be pursued

c.      Main diameter will be flush with the rear lip; no need to remove more material and complicate machining process

d.      Inside machining must allow for large fillets

e.      Attachment scheme for coldfinger anchor cannot employ tapped holes on the inside

4                   Rear Dewar Lid

a.      May add a grove to simplify support spider

b.      Feedthru pattern to be reversed 180°

c.      Single recessed (for oring/vacuum) surface for all connectors will be pursued

5                   Feedthrus

a.      Reverse pattern 180°

b.      .7” seperation of SMA pairs may be achievable; fittings will be modified by turning down the hex heads and nut, and adding spanner wrench features

6                   Inner Connect boards

a.      Caps will be smaller; allowing a more compact arrangement

b.      Boards still in conceptual phase, may even be flex circuits; need to create 3D model for study

7                   Coldfinger attachment

a.      Silver straps must be flexible


B         Field flattener

1                   Convex side almost finished; surface quality near perfect; a little more processing to remove a few remaining pits

2                   To start on concave side soon; processing should take about a week


C            Electronics

8                   Inner connect boards

a.      Smaller surface mount caps will be used to reduce the volume envelope

b.      Possibility of boards on a flex circuit will be investigated

1                   Feedthrus

a.      The smaller 51 pin DSUB connectors will be used

2                   Pre-amp electronics

3                   Electronics box

4                   Foot locker

a.      Barry to order boards and spares for VME crate

5                   CCD controller

a.      Barry to order boards and spares

b.      Chris to contact Bob Leach and ask about single channel video boards; Barry will use 75% factor based on existing boards


D         Left to do:

3                   Spec groove dimensions & o-rings

4                   Fix feedthru specs

5                   Establish inner board location (height position)

a.      Still in development and conceptual studies

6                   Splash guard

7                   Optical baffle

8                   Set screw access

9                   Getter design

a.      Getter will be included; zeolite proposed; location will be on dewar housing off side

10               Window support system

a.      Is bezel needed for window?

11               Thermal spider extension support

a.      Design resting pad; no need to be screwed down

12               Heater resistors & temperature diode wire/routing

13               Thermal spider attachment to stage plate

14               Thermal & structural FEA


E            Questions

1                   Need for a getter

2                   Weld coldfinger pipe to dewar housing

3                   Need for cam (to set roll adjustment) – still undecided; leave in for now

4                   Dates for future meetings – nothing set; will work to schedule a repeat of this meeting in early August