Field Guide to Optomechanical Design and Analysis

161 Pages·2012·21.449 MB·English

by  Katie Schwertz, James H. Burge

Field Guide to
Optomechanical
Design and
Analysis
Katie Schwertz
James H. Burge
SPIE Field Guides
Volume FG26
John E. Greivenkamp, Series Editor
Bellingham, Washington USA
FFGG2266 ccoovveerrss aanndd ttiittllee..iinndddd 33 55//2211//1122 1100::3366 AAMM
LibraryofCongressCataloging-in-PublicationData
Schwertz,KatieM.
Fieldguidetooptomechanicaldesignandanalysis/Katie
M.Schwertz,JimH.Burge.
p.cm.–(Thefieldguideseries)
Includesbibliographicalreferencesandindex.
ISBN978-0-8194-9161-9
1. Optical instruments–Design and construction–
Handbooks,manuals,etc.2.Optomechanics–
Handbooks,manuals,etc.I.Burge,JamesH.II.Title.
TS513.S3852012
681.4–dc23
0
2012013233
Publishedby
SPIE
P.O.Box10
Bellingham,Washington98227-0010USA
Phone:[phone]
Fax:[phone]
Email:[email protected]
Web:http://spie.org
Copyright © 2012 Society of Photo-Optical Instrumenta-
tionEngineers(SPIE)
Allrights reserved.Nopart ofthispublicationmay bere-
producedordistributedinanyformorbyanymeanswith-
outwrittenpermissionofthepublisher.
The content of this book reflects the work and thought of
theauthor.Everyefforthasbeenmadetopublishreliable
and accurate information herein, but the publisher is not
responsible for the validity of the information or for any
outcomes resulting from reliance thereon. For the latest
updatesaboutthistitle,pleasevisitthebook’spageonour
website.
PrintedintheUnitedStatesofAmerica.
Firstprinting
IntroductiontotheSeries
Welcome to the SPIE Field Guides—a series of publica-
tions written directly for the practicing engineer or sci-
entist. Many textbooks and professional reference books
cover optical principles and techniques in depth. The aim
of the SPIE Field Guides is to distill this information,
providing readers with a handy desk or briefcase refer-
ence that provides basic, essential information about op-
tical principles, techniques, or phenomena, including def-
initions and descriptions, key equations, illustrations, ap-
plication examples, design considerations, and additional
resources. A significant effort will be made to provide a
consistent notation and style between volumes in the se-
ries.
Each SPIE Field Guide addresses a major field of optical
science and technology. The concept of these Field Guides
is a format-intensive presentation based on figures and
equations supplemented by concise explanations. In most
cases, this modular approach places a single topic on a
page,andprovidesfullcoverageofthattopiconthatpage.
Highlights, insights, and rules of thumb are displayed in
sidebars to the main text. The appendices at the end of
each Field Guide provide additional information such as
related material outside the main scope of the volume,
keymathematicalrelationships,andalternativemethods.
Whilecompleteintheircoverage,theconcisepresentation
maynotbeappropriateforthosenewtothefield.
The SPIE Field Guides are intended to be living
documents. The modular page-based presentation format
allows them to be easily updated and expanded. We are
interested in your suggestions for new Field Guide topics
aswellaswhatmaterialshouldbeaddedtoanindividual
volume to make these Field Guides more useful to you.
Pleasecontactusatfi[email protected].
JohnE.Greivenkamp,SeriesEditor
CollegeofOpticalSciences
TheUniversityofArizona
FieldGuidetoOptomechanicalDesignandAnalysis
FieldGuidetoOptomechanicalDesignand
Analysis
Optomechanics is a field of mechanics that addresses
the specific design challenges associated with optical
systems. This Field Guide describes how to mount optical
components, as well as how to analyze a given design.
It is intended for practicing optical and mechanical
engineers whose work requires knowledge in both optics
andmechanics.
Throughout the text, we describe typical mounting
approaches for lenses, mirrors, prisms, and windows;
standard hardware and the types of adjustments
and stages available to the practicing engineer are
also included. Common issues involved with mounting
optical components are discussed, including stress, glass
strength, thermal effects, vibration, and errors due to
motion. A useful collection of material properties for
glasses, metals, and adhesives, as well as guidelines
for tolerancing optics and machined parts can be found
throughoutthebook.
ThestructureofthebookfollowsJimBurge’soptomechan-
ics course curriculum at the University of Arizona. We of-
fer our thanks to all those who helped with the book’s de-
velopment and who provided content and input. Much of
the subject matter and many of the designs are derived
fromtheworkofPaulYoderandDanVukobratovich;their
feedbackisgreatlyappreciated.
KatieSchwertz
EdmundOptics®
JimBurge
CollegeofOpticalSciences
UniversityofArizona
FieldGuidetoOptomechanicalDesignandAnalysis
v
TableofContents
ListofSymbolsandAcronyms ix
ImageMotionandOrientation 1
OpticalEffectsofMechanicalMotion 1
LensandMirrorMotion 2
PlaneParallelPlate 3
GeneralImage-MotionEquations 4
ImageMotionExample 5
RigidBodyRotation 6
QuantifyingPointingError 7
ImageOrientation 8
MirrorMatrices 10
MirrorRotationMatrices 12
ConeIntersectingaPlane 13
Stress,Strain,andMaterialStrength 14
StressandStrain 14
Strain-vs-StressCurve 16
SafetyFactor 17
GlassStrength 18
StressBirefringence 20
PrecisionPositioning 22
KinematicConstraint 22
ExampleConstraintsandDegreesofFreedom 23
Semi-KinematicDesign 24
IssueswithPointContacts 25
PrecisionMotion 27
StageTerminology 28
LinearStages 29
RotationandTiltStages 30
ErrorsinStageMotion 31
PrecisionFasteningandAdjustments 32
StandardHardware 32
ExampleScrews 33
FastenerStrength 34
TighteningTorque 36
Adjusters 37
DifferentialScrewsandShims 38
LiquidPinning 39
ElectronicDrivers 40
Flexures 41
StiffnessRelationsforSingle-StripFlexures 42
FieldGuidetoOptomechanicalDesignandAnalysis
vi
TableofContents
ParallelLeafStripFlexures 43
Stiffness Relations for Parallel Leaf Strip
Flexures 44
NotchHingeFlexures 45
Adhesives 46
AdhesiveProperties 47
AdhesiveThicknessandShapeFactor 48
ThermalStress 49
ChoiceofBondSizeandThickness 50
MountingofOpticalComponents 51
LensMounts:OfftheShelf 51
LensMounting:Custom 53
CalculatingTorqueandClearance 54
PottingaLenswithAdhesive 55
ClampedFlangeMount 56
LensBarrelAssemblies 57
LensBarrelAssemblyTypes 58
Surface–ContactInterfaces 60
PrismTypes 62
Image-RotationPrisms 64
Image-ErectionPrisms 65
PrismandBeamsplitterMounting 66
Thin-WedgeSystems 68
WindowMounting 69
Domes 72
DomeStrength 73
Small-MirrorMounts:OfftheShelf 74
Small-MirrorMounts:Adhesivesand
Clamping 75
Small-Mirror Mounts: Tangent Flexure and
Hub 76
MirrorSubstrates 77
MirrorSubstrateExamples 79
Large-MirrorMounting:LateralSupports 80
Large-MirrorMounting:PointSupports 81
Large-MirrorMounting:ActiveSupports 82
Self-WeightDeflection:General 83
Self-WeightDeflection:ThinPlates 84
Self-WeightDeflection:ParametricModel 85
LightweightingMirrors 86
FlexuralRigidityofLightweightedMirrors 88
FieldGuidetoOptomechanicalDesignandAnalysis
vii
TableofContents
DesignConsiderationsandAnalysis 89
RMS,P–V,andSlopeSpecifications 89
FiniteElementAnalysis 90
Vibration 94
DampingFactor 95
Isolation 96
SystemAccelerationandDisplacement 97
ThermalEffects 98
HeatFlow 100
AirIndexofRefraction 102
Athermalization 103
PassiveAthermalization 104
ActiveAthermalization 105
DeterminingThermallyInducedStress 106
Alignment 107
OpticalandMechanicalAxisofaLens 108
AlignmentTools 109
Tolerancing 110
GeometricDimensioningandTolerancing 110
GD&TTerminology 111
GD&TSymbology 112
ISO10110Standard 113
Appendices 114
ToleranceGuides 114
Clean-RoomClassifications 117
ShippingEnvironments:Vibration 119
ShippingEnvironments:DropHeights 120
UnitConversions 121
Cost and Performance Tradeoffs for Linear
Stages 122
TorqueCharts 125
AdhesiveProperties 127
GlassProperties 130
MetalProperties 134
EquationSummary 136
Glossary 141
Bibliography 144
References 148
Index 149
FieldGuidetoOptomechanicalDesignandAnalysis
ix
ListofSymbolsandAcronyms
%TMC Percenttotalmasslost
%CVCM Percentcollectedvolatilecondensable
material
a Acceleration
A Area
CAD Computer-aideddesign
COTS Commercialoff-the-shelf
C Specificheatcapacity
p
CTE Coefficientofthermalexpansion
CVD Chemicalvapordeposition
d Displacement
d Distance
D Diameter
D Thermaldiffusivity
D flexuralrigidity
E Young’smodulus
f Focallength
F Force,load
f0 Naturalfrequency(Hz)
FEA Finiteelementanalysis
FEM Finiteelementmethod
g Gravity(9.8m/s2)
G Shearmodulus
GD&T Geometricdimensioningandtolerancing
h Height,thickness
IR Infrared
k Stiffness
K Bulkmodulus
K Fracturetoughness
c
K Stressopticcoefficient
s
l Length
L Length
LMC Leastmaterialcondition
LOS Lineofsight
m Magnification
m Mass
MMC Maximummaterialcondition
MoS Marginofsafety
n Indexofrefraction
NA Numericalaperture
NIST NationalInstituteofStandardsand
Technology
FieldGuidetoOptomechanicalDesignandAnalysis
x
ListofSymbolsandAcronyms
OPD Opticalpathdifference
P Preload
p Pressure
PEL Precisionelasticlimit
ppm Partspermillion(1 10 6)
−
×
PSD Powerspectraldensity
psi Poundspersquareinch
P–V Peaktovalley
Q Heatflux
r Radius(distance,i.e.,0.5D)
R Radius(ofcurvature)
RSS Rootsumsquare
RTV Room-temperaturevulcanization
t Thickness
T Temperature
UTS Unifiedthreadstandard
UV Ultraviolet
x,y,z Distancesinthe x,y,or zaxis
α Coefficientofthermalexpansion
β Therm-opticcoefficient(coefficientof
thermaldefocus)
γ Shearstrain
δ Deflection
∆T Changeintemperature
∆x Changeinlateraldistance(xaxis)
∆y Changeinlateraldistance(yaxis)
∆z Changeinaxialdistance
(cid:15) Emissivity
ε Strain
ζ Dampingfactor
θ Angle
λ Thermalconductivity
ν Poissonratio
ρ Density
σ Stress
σ Yieldstrength
ys
τ Shearstress
ω Frequency
ω Naturalfrequency(rad/s)
0
FieldGuidetoOptomechanicalDesignandAnalysis
ImageMotionandOrientation 1
OpticalEffectsofMechanicalMotion
When an optical element in a system is
perturbed, the produced image will be af-
fected.Anopticalelementcanbeperturbed
axially (despace), laterally (decenter), or
angularly(tip/tilt).
These effects are typically referred to as line-of-sight
(LOS) error. A dynamic disturbance of the LOS, for
example, vibration of a system, is typically called jitter.
Various sources of jitter in a system can tend to be
correlated.
LOS error can be measured from either object space
or image space. If measured from image space, the
error shows up as a displacement on the image plane.
If measured from object space, the error appears as an
angularshiftoftheobject.
The z axis in a coordinate system is typically defined as
the optical axis, which is the path or direction of light
passingthroughanopticalsystem.Itisassumedthatthis
axis passes through the theoretical center of rotationally
symmetricelements.
The term axial (as in axial motion) will therefore refer to
the z axis, whereas the term lateral refers to the x and y
axes.
FieldGuidetoOptomechanicalDesignandAnalysis