MAXIM Periscope Module

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MAXIM Periscope Module

• Electro-Mechanical
• Jason Budinoff
• 25 April 2003

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Mechanisms Overview
Shutter
Mirror 4
Mirror 3
Mirror 2
Mirror 1
Roll/Pitch/X translation mount
OPL control translation of daughter bench w/
mirrors 2 3
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Aperture Shutter 1

• Requirements
• Command to completely obscure periscope FOV 300
  cycles over 5 years on-orbit
• Duty cycle very low (close/open cycle once per
  observation)
• Desired Operational Features
• Rotate a thin (2mm) aluminum strip shutter into
  the periscope FOV upstream of the Thermal
  Pre-Collimator
• Power-off hold in either open or closed position
• 90 degree stoke
• No launch lock required
• Actuator
• 90 deg stroke latching solenoid
• May fail open and closed
• Low risk
• Flight heritage
• Power TBD estimate 3 Watt
• Sensor
• Reed switch or LED flags
• End position indication
• Open, Closed

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Aperture Shutter 2
Aluminum Shutter Blade
Thermal Pre-Collimator
Position Sensors
Latching Solenoid Actuator
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Differential Screw Drive Actuator 1

• Micrometer-based actuator used for mirror
  nano-pointing and nano-translation
• Power-off hold
• Low Speed
• No backlash
• No launch lock required
• /- 5mm (or more) stroke
• 1.5 nm resolution
• Closed-loop position servo removes mechanical
  non-linearity at the nm level
• 5 nm knowledge (limited by sensor)
• Coarse Adjustment Screw Provide long stroke
• Use of coarse adjustment greatly increases
  lifetime of actuator
• DC-Brushless motor drive
• Fine Adjustment Differential Screw provides
  nm-level adjustment
• 100 steps forward 99 steps back
• 1/P1-1/P2 1/Peffective
• DC-Brushless motor drive, 1-4 Watts _at_ 28V
• Lubrication
• Adequate for 5 years on-orbit
• Bray 601 grease

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Differential Screw Drive Actuator 2
Bellows Provides preload and torsional rigidity
for output shaft
Fine adjustment stator(coils)
Coarse adjustment stator(coils)
Fine adjustment rotor
Fine adjustment nut
Coarse adj rotor
T2,80 TPI LH
T1, 72 TPI
32 TPI Coarse
Output Shaft (rotates translates)
Housing (fixed to ground)
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Optical Path Length (OPL) Control 1

• Requirements
• Command a change in periscope OPL for 5 years
  on-orbit
• Duty cycle very low (once per observation)
• 1 micron resolution
• /- 1.5 mm range
• Desired Operational Features
• Linear Translation of mirrors 2 and 3 in X
  direction (perpendicular to periscope boresight)
• No change in pointing during motion
• No change in delta-h value during motion
• Power-off hold
• No launch lock
• Flexure-based
• Actuator
• Single Coarse/Fine Differential Screw Drive
• Sensor
• Single 20 um pitch glass scale encoder resolution
  to lt0.2 um
• BEI or Micro-E

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Optical Path Length (OPL) Control 2

• Overall Assembly

Mirror 2
Daughter Bench
Mirror 3
Optical Bench
Linear Encoder between benches for OPL
displacement measurement
Front View
OPL Actuator
2 Linear Encoders for h measurement
Mirror 2 Mount
Mirror 3 Mount
Parallel Blade Flexures
Back View
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3-DOF Mirror Mount Mechanisms 1

• Mirror 4 Articulation Requirements
• Command following adjustments to mirror 4 for 5
  years on-orbit
• Linear Translation in X direction
• h adjustment
• /- 2 mm stroke
• 1.7 nm resolution
• Rotation about mirror Y axis (Pitch)
• /- 5 arc sec stroke
• 0.0023 arc sec (2.3 milli-arc sec) resolution
• Rotation about mirror Z axis (Roll)
• /- 300 arc sec stroke
• 0.13 arc sec resolution
• Duty cycle very low (once per observation)
• Desired Operational Features
• Decoupled motion
• Pitch and Roll about optical surface geometric
  center null point
• No change in translation during Pitch or Roll
  adjustment
• No change in pointing during translation
• Power-off hold

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3-DOF Mirror Mount Mechanisms 2
Mirror 4

• Overall Assembly

Mirror Mount Invar buttons bonded to bosses on
rear mirror surface 3 Ti tangent -blade flexures
Pitch 4-Bar Linkage Flexure
Bracket
Roll 4-Bar Linkage Flexure
Pitch Actuator
Roll Actuator
X-Translation Parallel Blade Flexures
X-Translation Actuator
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3-DOF Mirror Mount Mechanisms 3

• X-Translation
• Monolithic Parallel-Blade flexure
• parallelogram flexure
• Provides pure linear motion, weak coupling
  translation in pitch axis (Y)
• Periscope insensitive in this axis
• Simplified assembly alignment
• Uses Differential Screw Drive Actuator
• Sensor is Glass scale linear encoder used for h
  measurement

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3-DOF Mirror Mount Mechanisms 4

• Z-Roll Rotation

Mirror null rotation axis at center of optical
surface, at intersection of lines of action of
blade flexures
Differential Screw Drive Actuator
Monolithic 4-Bar Linkage Flexure, non-symmetric
Kaman KD 5100 inductive sensor quad
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Roll Photons
Mirror 4 Rolls through /- 5 degrees to
demonstrate (Exaggerated) beam path effects
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3-DOF Mirror Mount Mechanisms 5

• Y-Pitch Rotation

Mirror null rotation axis at center of optical
surface, at intersection of lines of action of
blade flexures
Monolithic 4-Bar Linkage Flexure, non-symmetric
Differential Screw Drive Actuator
Kaman KD 5100 inductive sensor quad
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Pitch Photons
Mirror 4 Pitches through /- 5 degrees to
demonstrate (Exaggerated) beam path effects
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Future Efforts

• Opto-mechanical analysis of mirror mounts
• Holding figure at 1/400 wave (mounted) will be
  difficult
• Design Test of Differential Screw Actuator and
  5 nm position servo
• IRD funds?
• Increase TRL from 3 to 5
• Further develop redundancy requirements
• Actuators
• Dual windings?
• Failure modes?
• Sensor
• Redundant pairs?
• Drive Electronics
• A-side, B-side?
• Cross strapping?
• Single motor driver for all similar actuators?
• Determination of failure mode for shutter
• Potential redesign?
• Mount on Spring-loaded release bracket?
• High-Output Paraffin (HOP) actuator