# Presentation: 410021

## MAXIM Periscope Module

**Electro-Mechanical**
**Jason Budinoff**
**25 April 2003**

## Mechanisms Overview

**Roll/Pitch/X translation mount**

**Shutter**

**Mirror**
**     ****3**

**Mirror**
**     ****2**

**Mirror**
**     ****4**

**Mirror**
**     ****1**

**OPL control translation of daughter bench w/ mirrors 2 & 3**

## 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

## Aperture Shutter 2

**Aperture Shutter 2**

**Latching Solenoid Actuator**

**Aluminum Shutter Blade**

**Position Sensors**

**Thermal **
**Pre-Collimator**

## 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 @ 28V
**Lubrication**
- Adequate for 5 years on-orbit
- Bray 601 grease
- Lubricant creep prevention
- Nye-bar barrier film channels
- Circuitous path

## Differential Screw Drive Actuator 2

**T1, 72 TPI**

**T2,80 TPI LH**

**32 TPI Coarse**

**Bellows**
**Provides preload and torsional rigidity for output shaft**

- Output Shaft (rotates & translates)

- Housing (fixed to ground)

**Fine adjustment nut**

**Fine adjustment rotor**

**Fine adjustment stator(coils)**

**Coarse adjustment stator(coils)**

**Coarse adj rotor**

## 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 <0.2 um
- BEI or Micro-E

## Optical Path Length (OPL) Control 2

**Overall Assembly**

**Optical Bench**

**“****Daughter” Bench**

**Mirror**
**     ****3**

**Mirror**
**     ****2**

**OPL **
**Actuator**

**Front View**

**Back View**

**Mirror**
**     ****3**
**Mount**

**Mirror**
**     ****2**
**Mount**

**Parallel Blade Flexures**

**Linear Encoder between benches for OPL displacement measurement**

**2 Linear Encoders for “h” measurement**

## 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
- No launch lock
- Flexure-based

## 3-DOF Mirror Mount Mechanisms 2

**Overall Assembly**

**X-Translation**
**Parallel Blade Flexures**

**X-Translation Actuator**

**Roll Actuator**

**Pitch Actuator**

**Roll**
**4-Bar Linkage Flexure**

**Pitch**
**4-Bar Linkage Flexure**

**Mirror 4**

**Bracket**

**Mirror Mount**
**Invar buttons bonded to bosses on rear mirror surface**
**3 Ti tangent -blade flexures**

## 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

## 3-DOF Mirror Mount Mechanisms 4

**Z-Roll Rotation**

**Monolithic 4-Bar Linkage Flexure, non-symmetric**

**Mirror “null” rotation axis at center of optical surface, at intersection of lines of action of blade flexures**

**Differential Screw Drive Actuator**

**Kaman KD 5100 inductive sensor quad**

## Roll Photons

**Roll Photons**

- Mirror 4 Rolls through
- +/- 5 degrees to demonstrate
- (Exaggerated) beam path effects

## 3-DOF Mirror Mount Mechanisms 5

**3-DOF Mirror Mount Mechanisms 5**

**Y-Pitch Rotation**

**Monolithic 4-Bar Linkage Flexure, non-symmetric**

**Mirror “null” rotation axis at center of optical surface, at intersection of lines of action of blade flexures**

**Differential Screw Drive Actuator**

**Kaman KD 5100 inductive sensor quad**

## Pitch Photons

- Mirror 4 Pitches through
- +/- 5 degrees to demonstrate
- (Exaggerated) beam path effects

## 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**
- IR&D 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