1. FRED
Coherence
FRED: A software tool
for modern engineering

2. What is FRED? FRED Overview
Comprehensive opto-mechanical systems design analysis tool
Stray light analysis (scatter and ghosting)
Coherent beam propagation
Imaging system design and photo-realistic rendering
Virtual prototyping
Opto-mechanical systems debugging (Forensic Optics)
Thermal self-emission analysis
Illumination design
Tolerancing, fabrication and testing
Both sequential and non-sequential raytracing modes
Multi-variable optimization capability

3. What is FRED? FRED Overview FRED
FRED can be used in virtually every step of the design process.
Initial proof of concept using catalog parts
Integration of optical and CAD designs
Full analysis of a virtual prototype including scatter, coatings, dispersion, absorption, volume scatter, diffraction, thermal emission, source characteristics…
Quickly manipulate model parameters for tolerance analyses
Integration with vendor catalogs for manufacturing or system debugging
Concept 1
FRED
Design 2
Analysis 3 4
Tolerancing 5
Manufacture

4. FRED Capabilities What are FRED’s Capabilities?
General complex field propagation
Birefringence
Default source types
Interferometry
Plane waves, spherical waves, Gaussian TEM00, Astigmatic Gaussian
Laser ranging
Precision metrology
Custom source types
Fiber coupling
Gaussian (Hermite, Laguerre, Laguerre Cosine, Laguerre Sine), R^n, Amplitude/Phase mask, Lambertian, Inverse Lambertian, cos^n, sin^n, Sampled
Wavefront decomposition
Partial coherence
Field polarization
Ray synthesis from arbitrary field data
Spatial resampling
Diffraction: Aperture, edge, slit, etc.
Multi-mode beam simulation

5. FRED Aperture Diffraction
Plane wave source diffracting from a triangular aperture

6. Obscuration Diffraction
FRED
Obscuration Diffraction
Diffraction from secondary mirror struts and baffle on a Cassegrain Telescope

7. FRED Fiber Coupling Fiber coupling efficiency Single Mode Step Index
Gaussian Mode
z-position CE

8. Near Field Diffraction
FRED
Near Field Diffraction
Fresnel zones – Near field diffraction structure

9. Polarization & Birefringence
FRED
Polarization & Birefringence
Alignment of a ruby laser with polarization filters and birefringent materials

10. FRED
Interferometry
Fizeau homogeneity test
Inhomogeneous material

11. FRED Partial Coherence a b c Diffractometer Degree of Coherence |12|
Pinhole spacing (mm) a b c A P1 P2 L1 L2 s1 L0 s0 F R
2o
21

12. FRED
Closing Remarks
General propagation of coherent fields using complex rays is proven and accurate
FRED provides engineers with a toolbox for modeling coherent systems
BASIC scripting compiler allows for custom analyses and source definitions
Capability can be expanded by linking with outside programs such as Excel, Matlab, and FDTD software