“budgeting” of optical systems
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“Budgeting” of Optical Systems. A Tutorial on Optomechanical Tolerancing and a Synopsis of the Economics Involved Ezra Milby OPTI 521 – Optomechanical Engineering Fall 2009 – Prof. J.H. Burge. Overview. Defining a System Performance Characteristic - PowerPoint PPT PresentationTRANSCRIPT
“Budgeting” of Optical Systems
A Tutorial on Optomechanical Tolerancing and a Synopsis of the Economics Involved
Ezra Milby OPTI 521 – Optomechanical Engineering
Fall 2009 – Prof. J.H. Burge
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 2
OverviewDefining a System
Performance CharacteristicDefining the Variable
Parameters of the SystemCreating a Tolerance
BudgetAnalyze Production CostsIterate the Design Process
for Optimization
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 3
Performance CharacteristicsImage Quality Physical ParameterMTFResolutionEnergy Distribution Spot SizeWavefront ErrorBeam DivergenceGeometrical AberrationsPSF
Bore sight ShiftEffective Focal LengthBack Focal Length DistortionImage Plane
Displacement
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 4
MTF WRT Defocus Error
Source: Smith (1985)
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 5
Primary ParametersSag (A)
Spacer Thickness (B)Contact Diameter (C)
Surface Radii (R)
Airspace
Source: Magarill (1999)
A variable parameter that is independent of adjustments in other parameters.
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 6
Primary ParametersCenter ThicknessSurface Sag Index of RefractionContact DiameterAxial Seat PositionClearance
WedgeSeat TiltContact Diameter
EccentricitySurface to Surface
DisplacementBase Diameter EccentricitySecond Barrel Clearance
Source: Magarill (1999)
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 7
Common Variable ParametersOptics AssemblyIndex of RefractionRadiusIrregularityThicknessSagDiameterWedgeSurface Roughness
AirspaceDecenter – AxiallyDecenter – LaterallyTilt Lens Roll
Assign Tolerances Base Cost
Tolerance BudgetError Type Units Tolerance Tolerance
ValueSensitivity WF Error
Φ (λ)
L1 Tilt deg +/- 0.10 0.1 0.132 0.011
L1 Decenter mm +/- 0.09 0.09 0.187 0.019
Airspace mm +/- 0.10 1.1 0.016 0.003
L2 Tilt deg +/- 0.10 0.1 0.192 0.018
L2 Decenter mm +/- 0.09 0.09 0.186 0.019
RSS 0.036
Assign a Tolerance Determine Sensitivity Determine Performance
Degrade Adjust as Needed
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 10
CostAssign a cost
sensitivity in tolerance budget
C = P·T + BAdjust tolerances to
minimize cost in the same way
Source: Willey (1984)
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 11
Glass Costs
Source: Willey (1992)
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 12
The Cost of Computing
Source: Willey (1983)Cost Savings
Engineering Salary
Mass ProductionHigh Cost Materials
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 13
The Iterative Tolerancing Process
Source: Ginsberg (1981)
April 22, 2023E. Milby - OPTI521 - Intro to Optomech Eng 14
Sources Burge, J. (2009). System LOS, RSS combination - Class Notes OPTI521. Ginsberg, R. H. (March/April 1981). Outline of tolerancing (from performance specification to toleranced
drawings). Optical Enginerering , 175-180. Lagger, J. P. (1982). Cost-Effective Design --- A Prudent Approach to the Design of Optics. Photnics Spectra , 65-
68. Magarill, S. (1999). Optomenchanical sensitvity and tolerancing. SPIE Conference on Optomechanical Design
and Engineering, (pp. 220-228). Denver, Colorado. Smith, W. J. (1985). Fundamentals of Establishing an Optical Tolerance Budget. Proc. of SPIE Vol. 0531,
Geometriucal Optics, ed. Fischer, Price, Smith . Willey, R. (1983). Economics in optical design, analysis, and production. Optical System Design, Analysis, and
Production, SPIE Vol. 399 , 106-111. Willey, R. (1992). Maximizing production yeild and performance in optical instruments through effective design
and tolerancing. Critical Review Vol. CR43, Optomechanical Design . Willey, R. (1983). Minimized cost through optimization tolerance distibution in optical assemblies. Proc. of SPIE
Vol. 0389, Optical Systems Engineering III , 12-17. Willey, R. R. (1984). The Impact of Tight Tolerance and Other Factors on the Cost of Optical Components. Proc.
of SPIE Vol. 0518, Optical Systems Engineering IV, ed. P.R> Yoder Jr. , (pp. 106-111).