performance. 07/2017: blanks generated. Zemax optical layout. 2017. Copyright Sigmadyne, Inc. ... Nastran models were created from CAD and Zemax models.
Integrating Optical, Mechanical, and Test Software (with applications to FreeForm optics) Vic Genberg & Greg Michels Sigmadyne, Inc Brian Myer & Todd Blalock Optimax Systems, Inc
October, 2017
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Outline 1) Overview STOP analysis. 2) SigFit I/F to Optic/FE/Test 3) Case Study: Free Form Telescope Telescope description Thermoelastic analysis Thermo-optic analysis 4) Summary
2017
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Integrated Modeling Flow Chart = STOP = Structural-Thermal-Optical-Performance Thermal Model
Thermal Loads
System Temperature Distribution
Mechanical Loads
Finite Element Structural Model
Optical Element Surface Displacements SigFit Rigid-Body Motions
SigFit Higher-Order Surface Deformations
Optical Element Stress Distribution SigFit Index Change: Wavefront Error
SigFit Birefringence: Polarization Errors
Optical Analysis Model
2017
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Optical Element Temperature Distribution SigFit Index Change: Wavefront Error
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SigFit Interfaces to Other Software Result Files
Finite Element Results NASTRAN ANSYS ABAQUS Solidworks Free Format Files
Rigid Body Motions Polynomial Coefficients Line-of-Sight Error Racking Deformation
Optical Analysis CODEV ZEMAX OSLO
SigFit Test Data Interferogram Files Grid Array Files Free Format Files
Control Systems Graphical Plotting MSC.Patran FEMAP ANSYS ABAQUS CAE PNG Files
2017
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State Space Files MatLab Files
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Case Study: Monolith Telescope Telescope design courtesy of Optimax Systems: Details: evolution of NASA notional 2-reflector design; uses 5 surfaces (3 freeform / 2 plano) to achieve diffraction-limited nominal, as-designed performance 07/2017: blanks generated
Zemax optical layout
2017
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Optomechanical analysis of free form monolithic telescope
2017
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Nastran models were created from CAD and Zemax models – Model geometry from CAD – Surface coordinate systems and optical prescription from Zemax
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Applied laser load to the system with absorption along beam path – Side surfaces had convection boundary condition
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Resulting temperature applied to structural model to get thermoelastic distortions
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SigFit read temperature results and calculated an OPD effect due to dndT – Wrote OPD effect to Zemax
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SigFit read displacements and fit with XY polynomials – Wrote surface distortions to Zemax Copyright Sigmadyne, Inc.
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Monolith Telescope – Zemax optical plot
Focal Plane
2017
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Plot of CAD and FE model Material = fused silica
FE model Tet10 automesh
CAD
2017
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Coordinate systems and XY poly obtained from Zemax model Optical path = s1 =>s3 => s7 => s11 => s14 => s15 s14
Free Form surfaces = s3, s7, and s11 = XY poly
s7
s1
s3
s11
2017
Flat surfaces = s1 and s14
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SigFit reads Zemax model for Coord Sys and XY poly prescription
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Nominal XY poly shape shown as sag deviation from flat (units=mm)
s14
s7 s3
s1 s11
2017
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Surface displacement (nm) due to -1C isothermal temperature change
2017
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Comparison of Surface Geometry and Surface Distortion
Surface Sag of Optical prescription
Surface distortion
Correct surface geometry is critical in FE model to get accurate deformations
2017
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Laser load applied: absorption along each path
Path 3-7
Path 7-11
Path 11-14 Start Path 1-3
2017
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Heat Transfer Results: Temperature increase (°C) due to laser load (absorption)
Steady State change in temperature With convection on 2 flat sides
Half model erased showing interior temperatures Hot spot at center where paths cross.
2017
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Plot of thermoelastic growth (magnitude in mm) for laser load
Kinematic support on entrance face
undeformed
2017
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Thermoelastic Results: Surface sag displacements (waves) due to laser load
Sag Displacement measured in Zemax surface coord systems
2017
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Sag after Best Fit plane Removed from each surface
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SigFit surface displacement output written to Zemax in zpl format ! Optic # = 5 OpticLabel=s5 ! Motion written in Vertex CID= 5 dz = 1.077391197809243E-04 SURP 005, BOR, 0 SURP 005, APU, 2 SURP 004, THIC, THIC(004)+dz SURP 005, THIC, THIC(005)-dz ! SurPoly Coeff added to Fitted Coeff for following Example = Surface 5 ! SurPoly renormalized to Fnorm and scaled to zpl units B$="XPOLYNOM" Surface displacement SURP 005,TYPE,B$ written as XY poly. SURP 005,PARM,1,0 SURP 005,EDVA, 14, 1 Zemax units = mm SURP 005,EDVA, 1.000000000000000E+00, 2 SURP 005,EDVA, 1.097614228536707E-07, 3 SURP 005,EDVA, 9.259883866275130E-08, 4 SURP 005,EDVA, 5.245707721083806E-04, 5 SURP 005,EDVA,-9.706166945869219E-11, 6 SURP 005,EDVA, 2.296240578769913E-04, 7 SURP 005,EDVA,-4.236949921660597E-11, 8 SURP 005,EDVA, 1.326970894690388E-07, 9 SURP 005,EDVA,-3.757949246043185E-11, 10 SURP 005,EDVA,-2.287243451265576E-07, 11 SURP 005,EDVA, 7.891186064907947E-09, 12 SURP 005,EDVA, 1.023150609882899E-13, 13 SURP 005,EDVA, 1.507585093886284E-08, 14 SURP 005,EDVA, 4.597044336086396E-14, 15 SURP 005,EDVA, 5.404222444136792E-09, 16
2017
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effect
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Thermo-optic OPD (waves) due to index change due to temperature (dndT effect)
OPD due to dndT along paths
OPD with best-fit plane removed
Integrated OPD along a path pasted on the first surface of the path.
2017
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SigFit OPD output due to dn/dT written to Zemax in zpl format ! ----------------------------------------B$="BINARY_1" SURP 004,TYPE,B$ SURP 004,PARM,1,0 SURP 004,PARM,0,9 SURP 004,EDVA, 14, 1 SURP 004,EDVA, 1.000000000000000E+00, 2 SURP 004,EDVA, 4.915719490633810E-02, 3 SURP 004,EDVA,-2.913178194988117E-01, 4 SURP 004,EDVA,-2.120302048174700E-02, 5 SURP 004,EDVA,-7.329620319824499E-04, 6 SURP 004,EDVA,-7.785351212021200E-03, 7 SURP 004,EDVA,-3.957661390565290E-05, 8 SURP 004,EDVA, 2.177250282906049E-04, 9 SURP 004,EDVA,-1.817112904686825E-05, 10 SURP 004,EDVA, 8.387021849559898E-05, 11 SURP 004,EDVA, 6.967863791656744E-06, 12 SURP 004,EDVA, 5.937864494978748E-07, 13 SURP 004,EDVA, 7.291061050084397E-06, 14 SURP 004,EDVA, 2.682149474942783E-07, 15 SURP 004,EDVA, 3.086550613745576E-06, 16
2017
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Example = Surface 4 Integrated OPD effect written as XY poly Units=waves at .6328 micron
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Zemax Results for Laser loading
Sag displacements only: rms spot size ~8 µm
dndt only: rms spot size ~45 µm
dndt has bigger optical effect than surface displacement
2017
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Second Load case: Gradient from Entrance to Exit surface
Exit Surface T = 1.0
Entrance Surface T = 0.0
2017
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Second Load case: Gradient from Entrance to Exit surface
Sag Displacement measured in Zemax surface coord systems after Best-Fit plane removed (units=nm)
2017
OPD due to dndT (index change) after Best-Fit plane removed (units=nm)
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Zemax Results for gradient from entrance to exit
Sag displacements only: rms spot size 2 - 3 X larger
dndt only: close to baseline
surface sag displacement has greater influence than dndt effect
2017
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SigFit calculates Line-of-Sight using internal ray trace algorithm
Gut Ray
2017
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SigFit calculates LoS motion due to surface distortions
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SigFit calculated the change in Line-of-Sight due to thermal gradient ------------------------------------------------------------------------------Line-of-Sight IMAGE SPACE error FP Surface Coordinate System used for X Y LI => Line of sight in Image Space LO => Line of sight in Object Space TX,TY => Translations (FE units) RX,RY => Rotations (Radians) TV,RV => Vector sum in XY plane Max => Largest abs value LoS of static load cases LI-TX -4.2615E-19
LI-TY 4.1947E-04
LI-TV 4.1947E-04
------------------------------------------------------------------------------
LoS at focal plane (units = mm) Located and output in coord system 15
2017
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Other SigFit capabilities •
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2017
Vibration analysis including random response – Line-of-Sight (LOS) Jitter – Jitter effects on MTF – Modal contributions Automated Linear Optics Model (LOM) – Calculate System WFE in vibrations including random State Space equations – LOS, Surface polynomials, LOM Active & Adaptive optic analysis – Actuator placement optimization – Stress optic polishing Stress Birefringence effects
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FreeForm optics in SigFit Surface Shapes Flat Conic Biconic Anamorphic Grazing conic Ogive Conic+any poly Offset segments FEA(No Eqn)
Polynomials Zernike Fringe Zernike Annular Zernike Asphere Forbes QCON Forbes QBFS XY Legendre Fourier‐Legendre
Disturbances Finite element results Polynomials Vector data Interferogram arrays Combinations of above
FE Programs Nastran (all) Ansys (all) Abaqus SolidWorks
Optics Programs CodeV Zemax Oslo Interferometers
Surfaces can be any standard shape (column 1) plus any polynomial in column 2. Offset segments of Asphere are a common FreeForm surface. Disturbance can be analysis data (FE results), test data (interferogram arrays), polynomials (any type & normalization), external source (vector data), or linear combinations SigFit can create an FE mesh of the surface, or correct an approximate mesh to exact surface
2017
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Summary
2017
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STOP modeling using SigFit integrates – Optical design codes – Mechanical CAD (Geometry) – FE analysis (Thermal & Structural) – Test software (Interferogram files)
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Analysis of FreeForm optics is straightforward with FE and SigFit
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Thanks to Optimax for their support!
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More information available at: www.sigmadyne.com
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