© Fraunhofer

STARTSYSTEMGENERIERUNG FÜRFREIFORMFLÄCHEN

25.11.2016Britta Satzer1, Herbert Gross1,2

(1) Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Jena, Germany(2) Institute of Applied Physics, Friedrich-Schiller-University Jena, Germany

KoSimO Status Seminar

© Fraunhofer Britta Satzer, 25.11.2016

Generation of starting configurations withfreeform surfaces – Outline

� Motivation

� Work on different generation methods for several system types

� 3D-SMS

� Introduction

� Implementation within complex optical systems

� Conclusion

� Summary and Outlook

© Fraunhofer Britta Satzer, 25.11.2016

Motivation - Typical design approach for complex optical systems

� Starting system

� From lens databases, patents, literature

� Formulation of the merit function

� Optimization

Final Design

Optimization

Starting System

© Fraunhofer Britta Satzer, 25.11.2016

Motivation - Design for freeform optical systems

� Only few starting designs available

� Higher variety of possible system geometries

Starting System

?Final Design

Optimization

© Fraunhofer Britta Satzer, 25.11.2016

Work on different generation methods- for several system types

Methods Types

Classical TMA

Gaussian Brackets Spectrometer

Conic confocal +Lokal Expansion

Monolith

Thin-componenttheory +Li and Cen

Scheimpflug

Korsch Calculation Modular Off-Axis

Wavefront mapping Zoom

3D-SMS Illumination

Ray mapping …

…

KoSimO

Y. Zhong, C. Liu, N. Fitzgerald,

C. Bösel, J. Hartung

���� Benchmark

© Fraunhofer Britta Satzer, 25.11.2016

Work on different generation methods- Implementations

Methods Ways of Implementation

Classical

Gaussian Brackets� Macro

Conic confocal +Lokal Expansion

� Macro

Thin-componenttheory +Li and Cen

� Method

Korsch Calculation ���� Analysis tool

Wavefront mapping ���� Matlab tool

3D-SMS ���� Matlab tool

Ray mapping ���� Numerical method

…

KoSimO

Y. Zhong, C. Liu, N. Fitzgerald,

Christoph Bösel, Johannes Hartung

KoSimO

© Fraunhofer Britta Satzer, 25.11.2016

� Method: Design of two lens surfaces for the ideal image of two fieldpoints developed by Prof. Miñano

� KoSimO: 3D-SMS for Scheimpflug system

3D-SMS Simultaneous Multiple Surface method - Introduction

Map of spotsize

Ref.: Satzer B., et.al., “Using the 3D-SMS for finding starting configurations in imaging systems with freeform surfaces“, SPIE Proc. Vol. 9626 (2015)

© Fraunhofer Britta Satzer, 25.11.2016

3D-SMS within complex optical systems- Approach

Start design with extended Zernike DLL

Final system

Optimization

Optics Studio

Rotational symmetric starting system, start parameter, incl. OPLs

Analytic surface representation: Zernike

3D-SMS

Data fit with Zernike

v

MATLAB

Lens surfaces as discrete point set

DDE -Link

© Fraunhofer Britta Satzer, 25.11.2016

3D-SMS within complex optical systems- Implementation

Optics Studio

Matlab

System

Raytracing

� Ray path in intermediate distances

� Conventional SMS calculation

� Optimizations on matching thecorrect optical path length (OPL)

� Ray path in intermediate distances

� Conventional SMS calculation

� Optimizations on matching thecorrect OPL

DDE - Link

ReversedSystem

© Fraunhofer Britta Satzer, 25.11.2016

-3.25E-003

-2.67E-003

-2.10E-003

-1.53E-003

-9.53E-004

-3.79E-004

1.95E-004

7.69E-004

1.34E-003

1.92E-003

2.49E-003

-3.10E-003

-2.56E-003

-2.02E-003

-1.47E-003

-9.32E-004

-3.89E-004

1.54E-004

6.97E-004

1.24E-003

1.78E-003

2.32E-003

3D-SMS within complex optical systems- Results

� Rotational symetric object and image planes

� Scheimpflug system

3.110��

�3.110��

2.510��

�3.510��

0 0

Surface Sag [mm]

© Fraunhofer Britta Satzer, 25.11.2016

3D-SMS within complex optical systems- Conclusions I

Pros:

� The positions of two object and image points can be calculated directly.

� Starting configurations for more than one field point can consider tilted object- and image planes in the starting design like Scheimpflug systems.

Cons:

� No algorithm known yet on using SMS for more than two field points for full ray bundle.

� Approach requires high optimization effort (surface fit and ray tracing in complex system), which make the approach time consuming and dependent on the success of the optimization.

� Best positions are limited to close to the pupil plane.

© Fraunhofer Britta Satzer, 25.11.2016

3D-SMS within complex optical systems- Conclusions II

General:

� Implementation in complex systems causes inaccuracies, since the path of the light is not reversible due to higher order aberrations. This has been treated with optimizations routines.

� Generally good starting systems have only few variables to allow better optimization. Thus the fitted freeform terms should be selected to a minimum

© Fraunhofer Britta Satzer, 25.11.2016

Summary and Outlook

� Implementation of 8 different methods for generation of startingconfigartions

� Application to several system types

Outlook:

� Finalization of the method implementation

� Benchmark

� Systematic for design of freeform lenses