80693e6b - 1.0 - Back End Optics and Cameras Technical Design Description.pdf

ITER UPPER WIDE ANGLE VIEWING SYSTEM PROJECT

55.GA UWAVS TECHNICAL DESIGN DESCRIPTION FOR

BACK-END OPTICS AND CAMERAS

Sponsored by Oak Ridge National Laboratory c/o Princeton Plasma Physics Laboratory

Under Subcontract No: S013437

Prepared by General Atomics

304243-R00028 Revision A

GA Project 30424

PPPL APPROVAL

VERSION Date Signatory QA Engineer SE External

ITER

Reviewer

Approver

1.0 5/28/2024

Mark Smith Patrick Temple Pete Dugan N/A Ravinder Bhatia

SEE EDRM

Notification

N/A

304243-R00028 Revision A

ITER UPPER WIDE ANGLE VIEWING SYSTEM

PROJECT

55.GA UWAVS TECHNICAL DESIGN

DESCRIPTION FOR BACK-END OPTICS AND

CAMERAS

Sponsored by Oak Ridge National Laboratory c/o Princeton Plasma Physics Laboratory

Under Subcontract No: S013437

Prepared by General Atomics PO Box 85608

San Diego, CA 92186-5608

GA PROJECT 30424

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55.GA UWAVS TDD FOR BACK-END OPTICS AND CAMERAS 304243-R00028/A

ii

REVISION HISTORY

Revision Date Description of Changes

A See

Watermark Initial Release

POINT OF CONTACT INFORMATION

PREPARED BY:

Name Position Email Phone

Colby Conant Mechanical Engineer Colby.Conant@ga.com 858-455-3933

APPROVED BY:

Name Position Email Phone

David Chan

Sean McCartney

Anthony Gattuso

Quality Engineer

Lead Engineer

Program Manager

David.Chan@ga.com

Sean.McCartney@ga.com

Anthony.Gattuso@ga.com

858-455-3657

858-248-6652

858-455-2910

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TABLE OF CONTENTS

REVISION HISTORY .................................................................................................................. II

POINT OF CONTACT INFORMATION ....................................................................................... II

ACRONYMS ........................................................................................................................... VIII

1 INTRODUCTION

1.1 Purpose

1.2 Scope

1.3 Definitions

1.3.1 Units

1.3.2 Coordinate Systems

1.3.3 Geometry

2 BACK END OPTICS & CAMERAS (BEOC) SUBSYSTEM OVERVIEW

2.1 Key Functions

2.2 Primary Subassemblies

2.3 Functional Flow Block Diagram

2.4 BEOC Subsystem Size, Weight, and Power (SWaP)

3 BEOC DETAILED DESIGN SUMMARY

3.1 Optical Layout

3.1.1 A70 – Full Spectra Windows and Mirrors

3.1.2 A80 – Infrared Mirrors and Field Lens

3.1.3 A90 – Infrared Lens Array

3.1.4 A100 – Visible Mirrors and Achromatic Doublet

3.1.5 A110 – Visible Lens Arrays

3.1.6 Visible Filter Wheel Assemblies

3.1.7 Calibration Optics and Sources

3.2 Opto-Mechanical Design

3.2.1 Optical interface - Optic Retention and Flexure Design

3.2.2 Optical Mount Assemblies

3.3 Visible Filter Wheel Assembly

3.3.1 Design Overview

3.3.2 Filter Selection Matrix

3.3.3 Stepper Motor Operation

3.4 Cameras

3.4.1 IR Cameras

3.4.2 VIS Cameras

3.5 Structures and enclosure

3.5.1 Optical Bench Assembly

3.5.2 Shielded Cabinet Assembly

3.6 BEOC Interfaces and Services

3.6.1 Interface plate

3.6.2 Electrical services

3.6.3 Cooling services

3.6.4 Beam Shrouds

3.6.5 Secondary Channel

4 INSTRUMENTATION AND CONTROLS

5 REFERENCES

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APPENDIX A OPTIC LOAD AND STRESS CALCULATIONS ............................................... A-1

APPENDIX B STEPPER MOTOR OPERATION CALCULATIONS ........................................ B-2

APPENDIX C MATERIAL SUMMARY.................................................................................... C-1 ea se d

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LIST OF FIGURES

Figure 1. Coverage of divertor from a) one UWAVS diagnostic and b) five Upper Port UWAVS diagnostics

Figure 2: 55.GA UWAVS diagnostic system

Figure 3. Back-End Optics and Cameras (doors removed for clarity)

Figure 4. BEOC main optical layout

Figure 5. BEOC functional flow block diagram

Figure 6. BEOC size overview

Figure 7. A70 full spectrum optic group

Figure 8. A80 infrared optic group

Figure 9. A90 infrared lens array group with infrared cameras

Figure 10. A100 visible optic group

Figure 11. A110 visible lens array group with visible cameras

Figure 12. Visible filter wheel assemblies mounted to underside of visible bench assembly

Figure 13. Calibration optical layout

Figure 14. Detail view of precision and cylindrical pad interfaces on A80-M2

Figure 15. Cantilever flexure detail for flat mirrors

Figure 16. Detail section view of annular flexure ring on A100-L1L2

Figure 17. Threaded retaining ring and spacer application in A90-CH A lens barrel

Figure 18. Detailed interface between threaded retaining rings/spacers and lens

Figure 19. Typical pinned interface for BEOC optic mounts on A70-W1

Figure 20. Monolithic optic mounts in the UWAVS BEOC

Figure 21. Two-piece kinematic mounts in the UWAVS BEOC

Figure 22. Explode of A100-M2 with Spherolinder kinematic mount detail

Figure 23. Kinematic mount optic cell with mounting tab cone grove detail

Figure 24. Kinematic mirror mount base - v-grove assembly for adjustment

Figure 25. Two-piece and monolithic lens cell assemblies

Figure 26. Explode view of A100-L1L2 lens cell assembly

Figure 27. Interface with the polished lens surface negates alignment errors due to (a) tilted rim and (b) decentered rim

Figure 28. Lens array tube assemblies for IR (A90) and VIS (A110) spectrum bands

Figure 29. Cross section of A90 IR lens barrel

Figure 30. Cross section detail view of A90 lens barrel pilot, threading, and axial shim gap

Figure 31. Explode view of visible filter wheel assembly

Figure 32. Explode view of populated filter wheel subassembly

Figure 33. Visible filter wheel assembly (a) motor interface and (b) position sensor interface. .. 28

Figure 34. Stepper motor torque vs speed curves for (a) U17-1 and (b) U17-2 magnet sizes ... 29

Figure 35. Infratec ImageIR 9300 IR Camera with mounted cold plate

Figure 36. Visible camera channel A and B mounted on linear stages

Figure 37. BEOC Optical Bench Assembly

Figure 38. Main optical bench assembly explode view

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Figure 39. BEOC Main Optical Bench supporting hardware (a) adjustable bushing, (b) standard pedestal, and (c) pinned pedestal

Figure 40. IR bench assembly

Figure 41. Visible optical bench assembly

Figure 42. Explode view of shielded cabinet assembly components

Figure 43. Stainless steel gamma shielding structure

Figure 44. Port side shifted gamma shielding for clearance and access

Figure 45. Neutron shielding B4C brick and assembly into rail channel system

Figure 46. Magnetic iron shielding layer

Figure 47. Detail views of (a) front industrial hinge, (b) bottom caster assembly, and (c) top roller assembly

Figure 48. BEOC maintenance door operation (a) first front door swings open, (b) second sliding door, (c) third sliding door, and finally (d) fourth sliding door

Figure 49. BEOC shielded enclosure locking detail views

Figure 50. BEOC interface plate mounted on PCSS with detail view of puck and pedestal hardware

Figure 51. BEOC interface plate alignment pucks facilitate X/Y in plane translation

Figure 52. BEOC enclosure pedestals with (a) pinned interface and (b) standard interface

Figure 53. BEOC electrical service system (1) internal cable routing (2) intermediate adapter cable and (3) PCSS external cable routing

Figure 54. BEOC electrical service disconnects for internal, external and PCSS locations

Figure 55. BEOC cooling services interface at FWD top and internal routing to equipment

Figure 56. BOL to BEOC beam shroud (a) telescoping section and (b) bellow ea se d

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LIST OF TABLES

Table 1. Applicable CAD Models

Table 2. BEOC total weight

Table 3. BEOC total power consumption

Table 4. Visible filter wheel selection matrix

Table 5. Material Specification Table ...................................................................................... C-1 ea se d

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ACRONYMS

Acronym Description

BEOC Back End Optics & Cameras

BOL Bio-Shield Optical Labyrinth

CAL Calibration

CCWS Component Cooling Water Supply

CG Center of Gravity

CHWS Chilled Water Supply

COTS Commercial Off The Shelf

CTE Coefficient of Thermal Expansion

EM Electromagnetic

EWAVS Equatorial Wide Angle Viewing System

FoS Factor of Safety

FWD Forward

IO ITER Organization

IOT Interspace Optics Tube

IR Infrared

IS Interface Sheet

PC Port Cell

PCSS Port Cell Support Structure

PI Port Integrator

PID Piping and Instrumentation Diagram

RPS Rotations Per Second

TGCS Tokamak Global Coordinate System

UPP Upper Port Plug

UWAVS Upper Wide Angle Viewing System

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1 INTRODUCTION

The 55.GA Upper Port Wide Angle Viewing System (UWAVS) views the divertor in sections and provides machine protection (monitoring for overheating of surfaces), plasma control (basic and advanced), and physics measurement roles. UWAVS is located in UP 2/8 (RFDA), UP 11/14

(USDA) and UP 17 (EUDA). The UWAVS coverage of the divertor is shown in Figure 1.

Figure 1. Coverage of divertor from a) one UWAVS diagnostic and b) five Upper Port UWAVS diagnostics.

1.1 Purpose

The purpose of this document is the technical design description (TDD) of the Back End Optics and Cameras (BEOC) subsystem, as part of the ITER diagnostic 55.GA Upper Visible and

Infrared Wide Angle Viewing System (UWAVS). The BEOC subsystem resides in the ITER Ex-

Vessel Port Cell, and is baselined as a common, identical design between all five installed instances of UWAVS (Upper Ports 2, 8, 11, 14, and 17).

In subsequent sections, the BEOC subsystem design will be described as follows:

Subsystem overview

Subsystem and subassembly detailed design summary

Summary of interfaces and services

Instrumentation and control scheme summary

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1.2 Scope

This document provides detailed component design architecture, function, and methodology for the UWAVS (55.GA) BEOC subsystem at the preliminary design phase. The BEOC subsystem design is common for all five Upper Ports (2, 8, 11, 14, and 17).

High-level definitions of the UWAVS system architecture, decomposition, and functions are described in the UWAVS System Design Description Document [1].

1.3 Definitions

1.3.1 Units

The units of the international system (SI) are used unless otherwise stated.

1.3.2 Coordinate Systems

Coordinate system references are consistent with the ITER Tokamak Global Coordinate System

[2] unless otherwise stated.

1.3.3 Geometry

The CAD geometry referenced throughout this report is listed below in Table 1.

Table 1. Applicable CAD Models

Model CAD File

BEOC Assembly UWAVS_BEOC_SUBSYSTEM_ASSY.CATProduct, A.40 ea se d

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2 BACK END OPTICS & CAMERAS (BEOC) SUBSYSTEM OVERVIEW

The UWAVS architecture is based on a modular approach that includes key functional subsystems in and outside of the vacuum vessel as shown in Figure 2. The BEOC serves as the last UWAVS optical subsystem containing conditioning optics and the infrared (IR) and visible cameras.

Figure 2: 55.GA UWAVS diagnostic system.

2.1 Key Functions

The BEOC is located behind the Bioshield in the Port Cell (PC), the BEOC mounts to the Port

Cell Support Structure (PCSS) via an interface plate and shielded enclosure designed to protect the sensitive electronics and optics from radiation and contamination ingress.

Light enters the BEOC through a shielded shroud from the Bio-Shield Optical Labyrinth (BOL) and passes through a series of windows and mirrors that split the full spectral range into two wavelength bands (Visible and IR). Both IR and visible legs of the optical system consist of two cameras, and have lens doublets and respective fold mirrors and energy splitters to separate the light into two required camera channels. Finally, the wavelength bands are focused onto camera detectors via IR and visible lens arrays.

2.2 Primary Subassemblies

As seen in Figure 3, the BEOC consists of the optical relay system, the optical bench assembly, and the shielded enclosure. The optical bench assembly supports the optical relay system while the shielded enclosure protects the optics and sensitive electronics from both radiation and contamination. The BEOC is mated to the PCSS via an interface plate which allows in-plane translation to adjust for large initial installation tolerances within the Port Cell.

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Figure 3. Back-End Optics and Cameras (doors removed for clarity)

The optical relay system shown in Figure 4 is comprised of the A70, A80, A90, A100, A110 optics groups, a pair of filter wheel assemblies, the IR and visible cameras, and the calibration system.

The A70 optics group is a set of large windows, beam splitters, and folding mirrors that condition and separate the IR and visible light beams. The A80 optics group consists of a field lens, beam splitter and folding mirrors to direct the two IR frequency band beams to their appropriate cameras. The A90 optics consist of two identical lens tubes to focus an image for the two IR cameras. The A100 optics group consists of an achromatic doublet to correct the color aberration, a beam splitter, and folding mirrors to direct the visible light beams to the two visible cameras.

The A110 optics are a set of two lens tubes containing different optics that form an image for the

Channel A and Channel B visible cameras.

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Figure 4. BEOC main optical layout

To ensure accurate IR and visible measurements, a calibration assembly is also nested in the shielded enclosure. The calibration system consists of a set of lens and fold mirrors that bring light from a black body (IR) or integrating sphere (visible) into the into the beam path via the A70-

S1 splitter.

Prior to the lens tubes, a modular, actuated filter wheel assembly will be placed containing filters to isolate 10 frequency bands for the observation of specific elements as well as a set of neutral density filters. These filter wheel assembly modules are accessible for replacement in the event of a failure or desire for alternate filters.

The BEOC is exposed to lesser radiation and elevated temperature than the IOT and BOL, but not an inconsequential amount. In this case, the BEOC is enclosed in layers of shielding to minimize radiation and electromagnetic (EM) exposure, protecting electronics and cameras inside.

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2.3 Functional Flow Block Diagram

Figure 5 shows the BEOC subsystem block diagram that highlights function, decomposition, and key mechanical, optical, electrical, and cooling interfaces. Color codes and line types are noted in the legend.

Figure 5. BEOC functional flow block diagram ea se d

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2.4 BEOC Subsystem Size, Weight, and Power (SWaP)

The BEOC SWaP is closely tracked to ensure requirements are met as well as provide inputs for subsequent structural, thermal, and optical analysis. The size and volume of the BEOC in Figure

6 fits within the allocated space claim. BEOC weight and power is shown in Table 2 and Table 3 respectively. A list of high-level component materials can be found in APPENDIX C .

Figure 6. BEOC size overview ea se d

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Table 2. BEOC total weight

Item Part Number Component Qty

Weight

(kg)

Volume

(m3)

Total Weight

(kg)

Total Volume

(m3)

Optical Bench Assy 467.51

Main optical bench assy

Main optical bench 1 191.14 0.01 191.14

Main bench post 4 12.00 48.00

Main bench post - pinned 2 12.00 24.00

IR Breadboard assy

IR breadboard 1 34.06 0.01 34.06

IR Bench Support 1 26.45 26.45

VIS Breadboard assy

VIS Breadboard 1 103.61 103.61

VIS Bench Support 1 40.25 40.25

Optical Relay System - Main Path 99.57

A70-W1 1 3.73 3.73

A70-S1 1 2.57 2.57

A70-S2 1 5.95 5.95

A80-L1L2 1 10.57 10.57

A80-S1 1 3.32 3.32

A80-M1 1 2.77 2.77

A80-M2 (D-shape) 1 1.91 1.91

A90-Channel A 1 8.42 8.42

A90-Channel B 1 8.42 8.42

A100-L1L2 1 7.22 7.22

A100-S1 1 3.29 3.29

A100-M1 1 4.44 4.44

A100-M2 1 2.96 2.96

A110-Channel A 1 9.10 9.10

A110-Channel B 1 5.48 5.48

Filter Wheel Assy 2 9.712 19.42

Optical Relay System - Calibration Optic 39.32

CAL-VIS-L1 1 5.834 5.83

CAL-VIS-FM1 1 8.407 8.41

CAL-IR-L1 1 4.893 4.89

CAL-S1 1 3.284 3.28

CAL-M1 1 6.071 6.07

Heat shielding 1 10.832 10.83

Cameras / Electronics 105.21

Infratec 9300 IR Camera 2 4 8.00

Emergent HT-12000 VIS Camera 1 1 0.34 0.34

Mikrotron EoSense 4CXP VIS Camera 2 1 0.45 0.45

Mikron M330 IR blackbody source 1 80 80.00

Optronic OL 458-4 VIS integrating sphere 1 2.618 2.62

Comet AGS 4010a 7-16 RF Matching Box 2 6.9 13.80

Structures and Shielding 22224.10

Shielding Assembly 1 21424.80 21424.80

PCSS Interface plate + hdwr 1 799.3 799.30

Total Weight

(kg)

Total Volume

(m3)

22935.71 8.94

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Table 3. BEOC total power consumption

Item Part

Number Description Qty

Power Dissipation

(W)

Total Power

(W)

Op Temp.

Non-op Temp.

(C)

Relative Humidity (%, Non Condensing)

Infratec

Image IR

IR Camera 2 27 54 Op: -20 to 50

Non-Op: -40 to 70

EMV HT-

12000 VIS Camera 1 1 9 9

Op: 0 to 45 Non-Op: -30 to 60

Mikrotron Eosens

4CPX6

VIS Camera 2 1 10 10 Op: -20 to 40

Non-Op: -40 to 80 0 to 93

Mikron M330

IR black body source

1 3000 3000 Op: 0 to 44

Non-Op: -20 to 80 0 to 90

Optronic

OL 458-4

VIS integrating sphere

1 4.8 4.8 Op: 0 to 35 Non-Op: -

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3 BEOC DETAILED DESIGN SUMMARY

3.1 Optical Layout

In the following sections, the optics are decomposed by form and support function to highlight beam conditioning roles of each optic.

3.1.1 A70 – Full Spectra Windows and Mirrors

The A70 group in Figure 7 is the first set of optics in the relay system and is comprised of the

A70-W1 sapphire corrector, A70-S1 energy splitter, and A70-S2 dichroic splitter. The A70-W1 assembly is a 200x10mm sapphire optic housed in a monolithic, 6061-T6 aluminum mount, fixed to the forward BEOC shielded wall. A70-W1 optic is positioned at an angle which corrects for slight color aberrations caused by the downstream vacuum window. The dual function A70-S1 houses a thinner, 1mm thick sapphire optic in a monolithic 6061-T6 aluminum mount fixed to the main optical bench assembly. The first function of the A70-S1 optic is to direct roughly 10% of the full spectra light to the optional secondary channel and the second function is to direct light from the calibration optical leg into the main beam path. The last assembly, A70-S2, splits the broad spectrum light into visible and IR bands. Due to the need for alignment of the dichroic splitter, the

A70-S2 assembly is comprised of a two piece 6061-T6 aluminum mount that allows adjustment between the base and optic cell. The A70-S2 optic is a 200x145mm fused silica substrate at a

2.2 degree wedge.

Figure 7. A70 full spectrum optic group.

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3.1.2 A80 – Infrared Mirrors and Field Lens

The A80 optics group in Figure 8 is the first of two groups in the IR leg and resides on the IR optical bench at a 60 degree angle with respect to the main optical bench. Once IR light is directed upward by the A70-S2 dichroic it passes through the A80-L1L2 field lens assembly. Two lenses within A80-L1L2 assembly are retained in a 304 stainless steel lens barrel via 180mm diameter retaining rings. The A80-L1L2 lens assembly reduces pupil aberrations at the cold stop in the IR cameras, increasing signal to noise ratio for better imaging. Following the field lens assembly are two similar two piece 6061-T6 aluminum mount assemblies, A80-S1 and A80-M1 which allow for

IR wavelength separation and beam steering into the Channel B lens and camera respectively.

Due to tight space constraints and proximity to the beam, the A80-M2 mirror assembly is a 6061-

T6 aluminum monolithic mount which houses a D-shaped 118mm diameter optic which directs light into the Channel A lens and camera.

Figure 8. A80 infrared optic group.

3.1.3 A90 – Infrared Lens Array

The A90 optics group in Figure 9 is the last group in the IR leg and consist of two identical lens tubes to focus an image for the two IR cameras. The two piece lens barrels are held horizontally by a 304SS base about the center of gravity (CG) and retain seven lenses of varying sizes and substrates. The two-piece lens barrel eases assembly and provides an interface to adjust for axial focus compensation.

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Figure 9. A90 infrared lens array group with infrared cameras.

3.1.4 A100 – Visible Mirrors and Achromatic Doublet

The A100 optics group in Figure 10 is the first of two groups in the visible leg and resides on the main optical bench. Visible light transmits through A70-S2 and interfaces with A100-L1L2 achromatic doublet assembly. The A100-L1L2 lenses correct for spherical and chromatic aberrations and act as the first lens in the imaging telescope for the visible channel. The 230mm diameter achromatic doublet lenses are retained in a 6061-T6 aluminum lens cell and base with

17-7 stainless steel annular flexures. Following the A100-L1L2 assembly the visible light is split by A100-S1 50/50 energy splitter and directed to the visible lens tubes by A100-M1 and A100-

M2. A100-S1, A100-M1, and A100-M2 are all similar two-piece kinematic designs, differing only by their base which holds the mirror cells at their required angle and height. The two-piece kinematic optic mount design facilitates beam steering and alignment into the visible lens tubes and cameras. R el ea se d

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Figure 10. A100 visible optic group.

3.1.5 A110 – Visible Lens Arrays

The A110 optics group in Figure 11 is the last group in the visible leg and consist of two different lens tubes to focus an image for the two VIS cameras. The two-piece lens barrels are held vertically by a 304SS base about the center of gravity (CG) and retain nine lenses of varying sizes and substrates. The two-piece lens barrel eases assembly and provides an interface to adjust for axial focus compensation. Camera model and sensor sizes differ between Channel A and B, therefore two lens barrel designs were required to create the correct image size.

Figure 11. A110 visible lens array group with visible cameras.

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3.1.6 Visible Filter Wheel Assemblies

Prior to the visible lens tubes, a modular, actuated filter wheel assembly is mounted containing filters to isolate 10 frequency bands for the observation of specific elements as well as a set of neutral density filters. Three external gear tooth filter wheels stack in a housing enclosure and are actuated by radiation hardened stepper motors. Filter wheel position is sensed by a radiation hardened mechanical sensor that interfaces with a cam lobe on each wheel. The two visible filter wheel assemblies are mounted to the underside of the visible optical bench assembly via M6 screws as seen in Figure 12.

Figure 12. Visible filter wheel assemblies mounted to underside of visible bench assembly.

3.1.7 Calibration Optics and Sources

The calibration system consists of a set of lens and fold mirrors that bring light from a black body source (IR) or integrating sphere (visible) into the beam path via the A70 splitter. The two-level optical layout shown in Figure 13 has the visible leg mounted on the visible optical bench assembly and the IR leg mounted to the main optical bench assembly. Visible light is directed down to the main optical bench by CAL-VIS-FM1 and is combined with the IR leg via CAL-S1 dichroic splitter. The opto-mechanical construction of the calibration mounts uses the same design methods as the main optical path mounts.

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Figure 13. Calibration optical layout

3.2 Opto-Mechanical Design

3.2.1 Optical interface - Optic Retention and Flexure Design

3.2.1.1 Retaining and Mounting Stresses

For nonmetallic mirrors (optical crystals) and lenses, flexures or threaded retaining rings are implemented to adequately secure the optic to its respective metallic mount. Retention forces are designed to keep the optic secure and within stress limits during exposure to a 5g acceleration.

Unlike metals with well-established mechanical properties and damage thresholds, failure parameters for glass can vary greatly. Since brittle glass and ceramics typically fail in tension versus compression, tensile stresses are used as the design criteria for optic retention. A widely accepted threshold of 6.9 MPa (1 ksi) in [3] has proven to be 2-3 times greater on precision manufactured optical components [4]. In lieu of testing optic substrate samples for properties, a more relevant industry standard tensile stress tolerance of 13.8 MPa (2 ksi) is used as a threshold for calculation and analysis in APPENDIX A .

3.2.1.2 Cantilever flexures

For flat mirrors and splitters, the optic face is set on three precision pads held to tight tolerances directly opposing the flexures. The optic edge is registered on two cylindrical pads, creating a line contact about the thickness. Details for both precision and cylindrical pads are highlighted in

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Figure 14. This semi-kinematic approach eliminates bending stress from the flexure force and reduces the possibility of over constraining contacts. To constrain all degrees of freedom, three flexures provide force to register the optic against its face while one or more flexures register the optic about its edge. Rotation about optical axis Z is constrained by friction forces against the optical surface, face flexures, and opposing metallic surfaces.

Figure 14. Detail view of precision and cylindrical pad interfaces on A80-M2

Cantilever flexures are designed as 17-7 stainless steel beams fixed at one end, typically by one or two screws, that contact the optic at the opposing end with a cylindrical surface. To provide the required spring force, the flexures are deformed at the optic interface to a predetermined displacement. This displacement can be fine-tuned via shims as shown in Figure 15.

Figure 15. Cantilever flexure detail for flat mirrors el ea se d

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3.2.1.3 Annular flexures

Large diameter, heavier lenses in the system leverage large 17-7 stainless steel annular flexures.

The annular flexure design principles are consistent with cantilever flexures where the outer perimeter of the disc is restrained to the cell by a bolted flange and the inner perimeter interfaces with the curved optic surface. To reduce stress concentrations at the optic interface when deflected, a large radius is machined into the 17-7 stainless steel flexure at the inner circumference. Figure 16 shows a detailed section view of A100-L1L2 annular flexure, retaining flange, and line of force for the two achromatic doublet lenses.

Figure 16. Detail section view of annular flexure ring on A100-L1L2

3.2.1.4 Threaded retaining rings

For smaller diameter lenses, 304 stainless steel threaded retainer rings and spacer rings position and secure the optics within the lens barrels. Spacers can be precisely machined to tight tolerances to accurately locate the lenses, ensuring proper alignment. Retaining rings can be torqued to a desired preload and then staked in place with low-outgassing epoxy. Where possible, COTS sized retaining rings are used within the lens barrels however for larger lenses custom rings are required. A typical application of a lens positioned with a spacer and secured with a threaded retaining ring is depicted in Figure 17.

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Figure 17. Threaded retaining ring and spacer application in A90-CH A lens barrel.

In an effort to improve alignment accuracy while simultaneously mitigating stress concentrations, threaded retainers and spacers have a sharp edge contact at an obtuse 135 degree angle (Figure

18). Sharp corner interfaces provide the highest accuracy of axial position, however they have the potential for large contact stresses. An obtuse angle versus a typical 90 degree angle reduces the chance of stress concentrations by eliminating burs left from machining while maintaining the exact location of the optical interface needed for accurate lens positioning.

Figure 18. Detailed interface between threaded retaining rings/spacers and lens el ea se d

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3.2.2 Optical Mount Assemblies

The optical elements located in the BEOC vary in size and orientation, requiring unique optical mounts to properly fix to their respective bench or structure. Although each optic requires a unique mount, common design methods are used across all assemblies. Common optic mount groups can be broken out into four subsequent categories.

Each mount is pinned to its respective interface for alignment and bolted via M6 hardware. Raised pads located at each bolted interface are held to tight profile tolerances ensuring coplanarity while also alleviating flatness requirements for the entire base. Figure 19 shows a typical pinned interface with raised mounting pads on A70-W1. When possible, interface pads are limited to three to alleviate over-constraining the optic mount.

Figure 19. Typical pinned interface for BEOC optic mounts on A70-W1

3.2.2.1 Monolithic optic mount assemblies

Monolithic optic mounts in Figure 20 are designed for optics located in tight spaces or in instances where optical adjustment is not required.

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Figure 20. Monolithic optic mounts in the UWAVS BEOC.

As the description indicates, monolithic mounts are single piece, machined mounts made of 6061-

T6 aluminum. Aluminum is used over stainless steel for optic mounts and cells to reduce weight and stress at the optic interface. In comparison to stainless steel, aluminum has a lower elastic modulus and higher Poisson ratio allowing more elastic deformation at the optic interface, therefore increasing the contact surface and reducing stress. Cantilever flexures retain the optics as described in Section 3.2.1.2.

3.2.2.2 Kinematic optic mount assemblies

Two-piece kinematic optic mounts in Figure 21 are designed for instances where optical alignment compensation is needed.

Figure 21. Two-piece kinematic mounts in the UWAVS BEOC.

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The two main components of the mount being the optic cell and base are joined via a COTS kinematic Spherolinder mechanism from G2 Engineering [5]. The Spherolinder mechanism depicted in Figure 22 is comprised of a captive fastener with four components: 1) V-groove, 2) cone grove, 3) center Spherolinder, and 4) fastener stud which are all 400 series stainless steel.

To tip, tilt, and translate the optic cell with respect to the base, shims are placed between the

Spherolinder V-groove and base mounting surface shown in Figure 22.

Figure 22. Explode of A100-M2 with Spherolinder kinematic mount detail.

The optic resides in the optic cell and is restrained via cantilever flexures described in Section

3.2.1.2. The cell is made of 6061-T6 aluminum and is mated to the base at three points on tabs around the perimeter of the optic by the kinematic Spherolinder fasteners. On the underside of the mounting tab in Figure 23, the cone groove portion of the Spherolinder is located by 2mm pins and fastened via two M3 screws. Efforts were made to create common cells for optics of similar form and size.

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Figure 23. Kinematic mount optic cell with mounting tab cone grove detail.

The 6061-T6 aluminum base bridges the gap between the optic cell and respective mating optical bench or structure. Bases are unique to each optic within the BEOC due to varying angles, positions, and proximity to structures. The Spherolinder V-groove components are positioned in a kinematic “triple vee” orientation so that all grooves point toward the center of the mounting patter at the centroid of the optic (Figure 24). The benefit of the “triple vee” over other kinematic orientations (i.e., cone/vee/flat), is the optic cell self-centers about the centroid of the mounting points. Therefore, when the mount is subject to temperature variations and components shift due to material coefficients of thermal expansion (CTE), the center of the optic remains in position at the centroid.

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Figure 24. Kinematic mirror mount base - v-grove assembly for adjustment

3.2.2.3 Lens Cell assemblies

Two-piece and monolithic lens cell mounts shown in Figure 25 house larger diameter (>200mm) lenses in the main optical path and calibration leg.

Figure 25. Two-piece and monolithic lens cell assemblies.

Two-piece designs (A100-L1L2 and CAL-VIS-L1) versus monolithic designs (CAL-IR-L1) are needed for the following reasons. Monolithic designs would be a simpler approach however in the case of A100-L1L2, two lenses must be assembled from both sides to create the achromatic doublet so additional base was required. For CAL-VIS-L1, the large diameter lens cell shown previously in Figure 13 is nested in a cutout in the VIS optical bench so the base sits within the clear aperture.

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Figure 26 depicts typical 304 stainless steel retaining rings clamping the annular flexure rings described in Section 3.2.1.3 on A100-L1L2. The thickness and diameters of the annular flexure rings are tuned for the size and weight of each optic.

Figure 26. Explode view of A100-L1L2 lens cell assembly.

3.2.2.4 Lens tube assemblies

Custom internally threaded lens barrels are designed to accurately position optics in the A90 IR lens arrays and A110 VIS lens arrays. To meet optical performance parameters, the lens arrays require mechanical support that tightly positions each lens element radially and axially with respect to one another. Where applicable, the convex surface of the lens self-centers about the inner annulus of the spacer or retainer as seen in Figure 27 [3]. If no convex surface is present, a tight 25μm radial gap is maintained between the lens and barrel diameters to minimize misalignment. Figure 28 shows the three unique lens barrel assemblies designed for the IR A90 group and visible A110 group. R el ea se d

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Figure 27. Interface with the polished lens surface negates alignment errors due to (a) tilted rim and (b) decentered rim.

Figure 28. Lens array tube assemblies for IR (A90) and VIS (A110) spectrum bands

Each lens tube assembly is comprised of a 304 stainless steel lens barrel, 304 stainless steel base, and a variety of 304 stainless steel spacers and threaded retainers to position and secure each optic. Each assembly is similar in design, only differing in size and orientation. So, this section of the report will highlight the A90 lens tube assembly.

The lens barrel subassembly (Figure 29) is broken up into a forward (FWD) and AFT section to ease installation of the varying sized optics. The FWD and AFT sections are aligned within +/-

25μm via a pilot guide interface and threaded together. Figure 30 highlights A90 lens barrel pilot guide, M75 threaded interface, and additional gap to shim for axial focus adjustment.

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Figure 29. Cross section of A90 IR lens barrel

Figure 30. Cross section detail view of A90 lens barrel pilot, threading, and axial shim gap el ea se d

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3.3 Visible Filter Wheel Assembly

3.3.1 Design Overview

The filters required to isolate specific visible wavelength bands are mounted in an actuated filter wheel assembly as seen in Figure 31. The filter wheel assembly contains three external tooth filter wheels, a sensor assembly, and three motor assemblies all mated in a two-piece housing.

The wheels rotate about a 304 stainless steel shaft and grease free ball bearings.

Figure 31. Explode view of visible filter wheel assembly

Three 280mm diameter gears are made from 6061-T6 aluminum and contain six positions for

85mm diameter wavelength and neutral density (Nd) filters. Filters are retained by 17-7 stainless steel flexures which interface with a 6061-T6 aluminum contact pad to reduce optic stresses.

Wheel “home” position is indicated by a cam lobe that interfaces with a limit switch assembly. A populated filer wheel is shown in Figure 32.

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Figure 32. Explode view of populated filter wheel subassembly

Radiation hardened steppers motors drive the filter wheels via 30mm diameter spur gears press fit on a stainless steel shaft (Figure 33a). Radiation hardened limit switches [6] mounted to a 6061-

T6 aluminum bracket interface with the cam lobe on each filter wheel subassembly indicating

“home” position (Figure 33b).

Figure 33. Visible filter wheel assembly (a) motor interface and (b) position sensor interface.

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3.3.2 Filter Selection Matrix

Preliminary filter wheel position is shown in Table 4. Visible filter wheel selection matrix, with species wavelength lines defined in [7] below.

Table 4. Visible filter wheel selection matrix

Filter Wheel

Position

Measurement Parameter

H-Alpha Hydrogen

Be Beryllium

W Tungsten

C Carbon

Cu Copper

Ne Neon

Ar Argon

Kr Krypton

He Helium

Thermal Open

Filter Wheel

Wavelength

1 2 3 4 5 6 6 6 6 6 6

656.1 457.3 400.8 658.2 521.8 Open Open Open Open Open Open

Filter Wheel

Wavelength

6 6 6 6 6 1 2 3 4 5 6

Open Open Open Open Open 640.0 696.5 557.0 728.0 900.0 Open

Filter Wheel

Wavelength

TBD TBD TBD TBD TBD TBD TBD TBD TBD TBD 6

Nd? Nd? Nd? Nd? Nd? Nd? Nd? Nd? Nd? Nd? Open

3.3.3 Stepper Motor Operation

Radiation hardened stepper motors from Empire Magnetics [8] have been baselined for UWAVS ex-vessel actuation, however due to high radiation activation of cobalt in the motor magnet, modifications to the magnet composition could result in a decrease in performance [9]. Filter wheel operation torque and speeds were calculated in APPENDIX B to be 0.8 in-oz and 3.11 rps respectively and were verified to work with two motor magnetic sizes at 50% power (Figure 34).

Figure 34. Stepper motor torque vs speed curves for (a) U17-1 and (b) U17-2 magnet sizes el ea se d

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3.4 Cameras

The baseline camera selection does not occur until after final design, but a preliminary selection of visible and IR cameras is required for optical and mechanical integration activities. The following camera models were selected for preliminary design.

3.4.1 IR Cameras

For both IR channels A and B, the Infratec ImageIR 9300, water-cooled model was selected. With peak power of 55W and steady state of 27W, water-cooling the camera is necessary to keep it within operating temperatures. The cameras mate with the A90 lens tube assemblies via M60x1 lens interface and are supported by a base to the IR optical bench assembly. Channel A and channel B of the IR optical leg are depicted in Figure 35.

Figure 35. Infratec ImageIR 9300 IR Camera with mounted cold plate

3.4.2 VIS Cameras

Two separate camera models were temporarily selected for visible channels A and B [10]. For channel A the EMV HT-12000 camera was selected for high resolution imaging. For channel B the Mikrotron EoSens 4CPX6 model was selected for high speed capturing.

Thermal analysis indicated a need for focus compensation for both IR and VIS channels due to material CTE of the benches, structures, and optical mounts within each subsystem. A trade study

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To account for additional focus compensation, the visible cameras are mounted to stepper motor-driven linear stages affixed to vertical stainless steel mounts. Figure 36 depicts both Channel A and B cameras mounted to the visible optic bench.

Figure 36. Visible camera channel A and B mounted on linear stages.

3.5 Structures and enclosure

The BEOC structures and enclosures subsystem provides support for optics and instrumentation and protects electronics from the Port Cell environment. Two main assemblies comprise the structures and enclosures which are the optical bench assembly and the shielded cabinet assembly.

3.5.1 Optical Bench Assembly

The optical bench assembly is the main support system for the optics in the optical relay system.

The main optical bench, IR optical bench, and VIS optical bench assemble to create the optical bench assembly shown in Figure 37.

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Figure 37. BEOC Optical Bench Assembly

Each optical bench is baselined as a custom Commercial-off-the-shelf (COTS) honeycomb breadboard optical bench. Honeycomb optical benches are industry standard for optical laboratory environments because of their exceptional stiffness, vibration damping, surface flatness, standard threaded hole mounting patterns, and reasonable cost/availability. Standard benches are often configured for more specialized applications, hence the custom-COTS designation. Customized features for each are listed below:

316L stainless steel top/bottom sheets and honeycomb core. Edge welded and bonded using radiation compliant materials.

Pinned interfaces for bench posts, optic mounts, and optical instrumentation.

Custom threaded inserts for height (dZ), pitch (rY), and roll (rX) adjustment

3.5.1.1 Main optical bench

The main optical bench assembly shown in Figure 38 is the large, lower most bench that provides support to the A70 and A100 optic groups, as well as the IR and VIS optical bench and respective optic groups. The bench itself is a standard 110mm thick bench with a maximum footprint of

2600 x 750mm and standard M6 threaded holes on a 25 mm square pattern. Various levels are recessed into the main breadboard to locate the A100-M2 and CAL-IR-L1 optic mounts in the beam path.

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Figure 38. Main optical bench assembly explode view.

The main optical bench is supported by eight 304 stainless steel machined pedestals by M16 and

M20 mounting hardware as seen in Figure 39. Two port side pedestals, fore and aft, contain

20mm diameter pins to precisely locate the bench to the lower stainless steel shielding plate.

Mounting hardware clamps through a custom insert that’s threaded into a welded bushing in the bench similar to Newport Optics Microlock adjuster [11]. This insert shown in Figure 39a allows leveling of the bench.

Figure 39. BEOC Main Optical Bench supporting hardware (a) adjustable bushing, (b) standard pedestal, and (c) pinned pedestal.

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3.5.1.2 IR optical bench

The IR optical bench mounts at a 60 degree angle to support the A80, A90, and IR camera assemblies. The bench breadboard is 50mm thick with a footprint of 600 x 750mm and standard

M6 threaded holes on a 25 mm square pattern. Similar to the main bench, the IR bench has custom threaded height adjusters to level the assembly with respect to the optical system. Cutouts in the lower portion provide adequate beam clearance for the main beam and calibration beam paths (Figure 40).

Figure 40. IR bench assembly

The IR bench sits on two welded gussets that mate to the main optical bench by M6 fasteners and positions the IR breadboard at 60 degrees. The port side gusset has a circular aperture to provide the option for a portion of full spectrum light to be directed from A70-S1 to a secondary channel.

3.5.1.3 VIS optical bench

The VIS optical bench is the final optical bench in the BEOC and supports the filter wheels, A110 lens tubes, VIS camera assemblies, and the visible portion of the calibration system. The bench breadboard is 50mm thick with a footprint of 2600 x 750mm and standard M6 threaded holes on a 25 mm square pattern. On the underside are locally positioned M6 fastener holes for the visible filter wheels and mounting posts. Cutouts through the bench shown in Figure 41 allow beam clearance for A110 lens tubes and visible calibration leg.

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Figure 41. Visible optical bench assembly

The VIS bench is supported by eight 304 stainless steel post and bracket assemblies. The square posts are 325mm tall by 50mm with M8 rivet-nut inserts. Cross supports between the vertical posts bolt to the angle brackets with M8 hardware.

3.5.2 Shielded Cabinet Assembly

The shielded cabinet assembly provides two main functions: To protect BEOC electronics from radiation and magnetic loads, and to protect optics from dust ingress from the Port Cell. The primary components of the shielded cabinet assembly are the shielding layers and maintenance doors as shown in Figure 42.

Figure 42. Explode view of shielded cabinet assembly components.

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3.5.2.1 Shielding

The primary function of the shielded cabinet assembly is to attenuate both radiation and magnetic loads in the port cell to protect sensitive equipment in the BEOC assembly. Layers of magnetic, gamma, and neutronic shielding materials are stacked and assembled to create an enclosure to accomplish this task. Shielding layers, thicknesses, and retention methods are heavily based on

55.G1 (EWAVS) shielded cabinet assembly [12].

3.5.2.1.1 Gamma shielding

A 60mm thick layer of 316 stainless steel provides the required gamma radiation attenuation. Due to the strength and stiffness of 316 stainless steel, the gamma shielding also functions as the primary structure of the shielded cabinet assembly. The stainless steel structure in Figure 43 has cutouts for bench clearance, mounting points for optics and the optical bench assembly, tracks and hinges for maintenance doors, as well as fixation points for subsequent shielding layers.

Laterally across the center spans an I-beam assembly, comprised of 5inch I-beams and gussets, to support the top stainless steel plates at their joint.

Figure 43. Stainless steel gamma shielding structure.

The optical beam path is favored towards the port side of the BEOC so local gamma shielding in

Figure 44 is shifted to provide clearance for the optical bench assembly and various optics. To accomplish this, shielding is removed locally and a 2772mm x 912mm plate bolts to the port side.

Aside from providing clearance, the cutout allows additional access to the port side of the optical bench assembly during factory installation and testing.

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Figure 44. Port side shifted gamma shielding for clearance and access.

3.5.2.1.2 Neutron shielding

The outermost layer of the shielded cabinet is comprised of stacks of 25mm thick boron carbide

(B4C) plates to attenuate neutron radiation to acceptable levels. Pre-assembled B4C bricks slide into 316 stainless steel C-channels bolted to the shielded cabinet as seen in Figure 45. In addition to B4C, a 5mm layer of neutron absorbing cadmium is mounted under the stainless steel channels.

Figure 45. Neutron shielding B4C brick and assembly into rail channel system.

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3.5.2.1.3 Magnetic shielding

Magnetic shielding is accomplished using a 15mm thick layer of pure iron. The iron layer creates an inner shell when mounted to the inner surface of the stainless steel structure. Various cutouts shown in Figure 46 allow service access and optical bench and beam clearance.

Figure 46. Magnetic iron shielding layer.

3.5.2.2 Maintenance doors

To facilitate maintenance to BEOC optics and electronics, a front swinging door followed by a series of three sliding doors operate in series to allow access by personnel. Shielding compositions and thicknesses on the maintenance doors are consistent with the rest of the shielded cabinet assembly.

The front swinging door weighs 1275kg and mounts to the forward stainless steel panel via two industrial hinges rated to over 11000kg each. The three rolling doors weigh 1125kg and are supported by three bottom casters rated for 1900kg each. To prevent the sliding doors from tipping outwards, an assembly with six horizontal rollers bolts to the top of the door and tracks through a longitudinal guide in the top stainless steel structure. Detail views of the maintenance door hinge and caster/roller assemblies can be found in Figure 47.

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Figure 47. Detail views of (a) front industrial hinge, (b) bottom caster assembly, and (c) top roller assembly.

As previously mentioned, the maintenance doors operate in series to provide access to personnel.

First, the front swing door must be opened to its full extent and locked in place, exposing the IR optical bench and cameras. Next the first sliding door can be rolled forward, butted up to the first swing door, thus providing access to the VIS calibration optics and first visible camera assembly.

In a similar fashion, the remaining sliding doors can be rolled forward giving access to the second visible camera assembly and calibration sources. An overview of maintenance door operation is highlighted in Figure 48.

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Figure 48. BEOC maintenance door operation (a) first front door swings open, (b) second sliding door, (c) third sliding door, and finally (d) fourth sliding door.

To lock doors in place during operation and for safety while under maintenance, a variety of pins and bolts are located in the stainless steel structure to secure doors in different positions. Each sliding door has two positions for a locking pin at the forward and aft bottom of the steel layer.

When the sliding door is moved into position, a 20mm pin is inserted downwards through the door and into a hole in the bottom stainless steel track, locking it into position. This process can be performed at any location the door can reside, locking the door safely into position for maintenance or locking it closed for operation. Similarly, the front swinging door has one location at the forward bottom of the steel layer for a locking pin. The 20mm locking pin for the swinging door is only used to lock the door open for safety during maintenance. Finally, to close all doors for operation, all sliding doors are rolled into position with pins installed and the front swinging door is locked closed by a M24 bolt through the door into the structure. Details of both bolted connections and pin locks are shown in Figure 49.

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Figure 49. BEOC shielded enclosure locking detail views.

3.6 BEOC Interfaces and Services

This section provides a brief, high-level summary the BEOC subsystem external interfaces and service requirements. Detailed interface descriptions and associated data can be found in the following interface sheets (IS):

55.GA IS for UPP-02 [13]

55.GA IS for UPP-08 [14]

55.GA IS for UPP-11 [15]

55.GA IS for UPP-14 [16]

BEOC interface and service components facilitate delivery of general services from the Upper

Port Cell support structure to internal BEOC components, and provides other auxiliary functions to support installation, removal, and maintenance of the BEOC subsystem and its components.

The baseline design of the BEOC requires power and signal services to electrical components and cooling services to the IR cameras and IR calibration source.

3.6.1 Interface plate

The BEOC interface plate assembly facilitates the interface between the BEOC and the Port Cell

Support Structure (PCSS). The BEOC interface plate assembly also provides initial installation alignment/correction to overcome significant absolute installation tolerances of the PCSS per [17].

The BEOC interface plate assembly consists of the following components, as shown in Figure 50.

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BEOC interface plate – 55.GA defined in Port Integrator (PI) interface sheet.

Interface plate pucks and hardware.

Welded hardware [18] for BEOC enclosure pedestals.

Figure 50. BEOC interface plate mounted on PCSS with detail view of puck and pedestal hardware.