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

2. What is FRED? FRED Introduction
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 Introduction 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 Sources of Stray Light Common stray light sources include:
Diffraction
Specular ghosts
Grating effects from manufacturing
Scatter from structures
Particulate contamination
Thermal self-emission
Background sources
Bulk material effects

5. FRED Effects of Stray Light Stray light = performance reduction
Stray light should be accounted for during design
Correcting stray light requires knowledge of the source
FRED provides engineers a toolbox for stray light analysis

6. FRED Stray Light Tools Surface Scatter Models Lambertian Harvey-Shack
ABg
Phong
Diffuse Black Paint
Particulates (Mie)
Diffuse Polynomial
Diffuse Binomial
Tabulated BSDF
Tabulated PSD
K-correlation
User-scripted (BASIC)

7. FRED Stray Light Tools Scatter Importance Sampling
Scatter rays only into regions of interest
Saves time by raytracing efficiently
Correctly accounts for ray directions
Importance Sampling Options
Angular spread about specular
Angular spread about a given direction
Angular spread about a given point
Towards an entity
Through a closed curve
Through a volume

8. FRED Stray Light Tools Volume Scattering
Stray light effects can come from bulk material volume scatter
Implemented as “random walk” using a mean free scatter distance
Translucent materials, suspended particulates, etc.

9. FRED Stray Light Tools Surface Raytrace Controls
Allows specific interaction types: scatter, transmission, reflection etc.
Set ray power cutoff thresholds
Specify number of allowed ray splits due to scatter or specular
Precise control over model tracing
Applied to individual surfaces

10. FRED Stray Light Tools Raypaths and Stray Light Report
Keeps track of ray intersection paths
Sorts raypaths by scatter and specular
Reports scatter/ghost level
Provides information on ray count, path power, scatter/ghost surfaces
Paths can be marked for sequential tracing
Raypaths can be redrawn to the 3D view

11. FRED Stray Light Tools Diffraction Grating structures Linear
XY Polynomial with aspheric terms
Diffraction from apertures, edges, slits, etc. when tracing coherent rays

12. FRED Stray Light Tools BASIC Compiler and Scripting
FRED’s fully integrated BASIC scripting language allows for custom calculations such as thermal self-emission and PST

13. FRED Stray Light Example Ghosting in a Double Gauss Lens
10 degree off axis angle
Uncoated lenses
Allow only first order paths
straylight_ghostImage.frd

14. FRED Stray Light Example Ghosting in a Double Gauss Lens
Allow all raytrace paths
Irradiance distribution shows ghost image

15. FRED Stray Light Example Ghosting in a Double Gauss Lens
Use FRED’s Stray Light Report to identify the ghost path(s)
Ghost is caused by a reflection from surface 10

16. FRED Stray Light Example Ghosting in a Double Gauss Lens
Apply an AR coating to surface 10
Ghost image power reduced by an order of magnitude!

17. FRED Optimization Applications What is optimization used for?
Positioning geometry
Controlling geometry size
Modifying surface shapes
Detector power transfer efficiency
Field distribution, shape and size
Pattern structure variation
Color image analysis
User-defined merit functions and variables
Selection of Global and Local optimization methods

18. FRED Optimization Variables Default Variables Custom Variables
What variables are available?
Any entity property in the model can be a variable
Default Variables
Custom Variables
Position/Orientation parameters
Curvature
NURB control point X,Y,Z coordinates
NURB control point weights
Conic constant
Aspheric coefficients
Lens bending
Lens power
Lens thickness
Element volume boundary
User-defined BASIC script
Scripting commands give access to every parameter and function available in the GUI

19. FRED Optimization Metrics Custom Metrics Default Metrics
What metrics are available?
Custom Metrics
Default Metrics
Project specific requirements may necessitate user-defined custom metrics be used.
RMS spot size
Encircled spot radius
Maximum power on surface
Minimum power on surface
Uniformity
Centroid position
Distribution fit to data

20. FRED Optimization Example Optimize an LED Distribution
Use FRED to optimize an LED collimating lens for a uniform illuminance distribution by varying the lens surfaces.

21. FRED Optimization Example Optimize an LED Distribution
User-defined metric driven to a minimum by the simplex
Metric needs to account for both power and uniformity
Metric = SD/Power
Scripted metric is… BASIC
Calculate Illuminance
Calculate SD
Calculate Power Transfer
Return Metric Value

22. FRED Optimization Example Optimize an LED Distribution 55 LUX (lm/m )2
88.5 LUX (lm/m ) 2

23. Illumination Capabilities
FRED
Illumination Capabilities
What are FRED’s Capabilities?
CAD import/export from STEP and IGES
Catalog materials and components
Optimization capability
Photo-realistic rendering
Rayset import from file including:
Photometric power units (Lumens)
FCR ( FRED’s compact rayset )
Photometric analyses (Illuminance, Luminous Intensity)
RAY ( ProSourceTM )
Color image analysis
DAT ( ZEMAXTM, ProSourceTM)
DIS ( ASAPTM )
TXT( ASCII )
Default source types
Plane waves, spherical waves, Gaussian TEM00, Astigmatic Gaussian
Custom source types
Gaussian (Hermite, Laguerre, Laguerre Cosine, Laguerre Sine), R^n, Amplitude/Phase mask, Lambertian, Inverse Lambertian, cos^n, sin^n, Sampled
IES output

24. FRED CAD Import/Export
FRED reads and writes CAD files in STEP or IGES format
All surface types are exported (exception: user-scripted) with proper trimming
User-specified sampling for accuracy requirements
Default raytrace control assignment on import
NURB order reduction and curve simplification for tolerancing
Rays can be drawn and exported in color with the model

25. FRED Geometry FRED has 30+ default surface and curve types
Custom scripted geometries for added flexibility
Entities can be referenced to ANY coordinate system for accurate and dynamic positioning
Integrated component catalogs for rapid prototype development or proof of concept designs
CAD interface and object tree hierarchy for logical system organization and construction
Arbitrary surface trimming operations using surfaces and curves

26. FRED Ray Import/Export 1 2
FRED reads ray file formats RAY, DAT, DIS, TXT and writes formats FCR, TXT, RAY, DAT
Creating a model with ray data can be a simple two step process:
Open/Import geometry from file
Create source from ray file data
FRED’s advanced Ray Manipulation Utilities allows modification and filtering of rays before export
Rayfile import automatically sets the power of the source according to the power contained in the rays 1 2

27. Custom Source Creation
FRED
Custom Source Creation
FRED allows source customization using combinations of the following parameters:
Ray Positions
Spectral Range
Ray Directions
Spectral Weighting
Angular Power Apodization
Coherence
Positional Power Apodization
Polarization
Source Power Units
Digitization tools for data sheet specification
Source power can be radiometric or photometric units
Wavelengths can be specified using a sampled list or continuous spectral function

28. FRED Optimization FRED has a built in optimization engine
Default variables and aberrations and user-scripted variables and aberrations
Continuously expanding default optimization functionality
Uniformity Optimization
55 LUX (lm/m ) 2
Position/Orientation parameters
RMS spot size
Encircled spot radius
Curvature
Maximum power on surface
NURB control point X,Y,Z coordinates
Minimum power on surface
Uniformity
NURB control point weights
Centroid position
Conic constant
Distribution fit to data
Aspheric coefficients
Lens bending
Lens power
Lens thickness
Element volume boundary
88.5 LUX (lm/m ) 2
hybrid_optimization.frd

29. FRED Photometric Analysis
Sources can be defined in both radiometric and photometric power units
Wavelength spectrum can be sampled or functionally defined
Illuminance and Luminous Intensity calculations
User-defined detector response functionality
Color image calculations using both radiometric and photometric source definitions
lawnLamp.frd

30. Photorealistic Rendering
FRED
Photorealistic Rendering
FRED has the capability to render a scene photo-realistically
Scene objects be applied with physical optical properties
Scatter importance sampling and reverse raytracing allow for efficiency

31. Coherence Capabilities
FRED
Coherence 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

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

33. Obscuration Diffraction
FRED
Obscuration Diffraction
Diffraction from secondary mirror struts and baffle on a Cassegrain Telescope
cassegrain.frd

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

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

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

37. FRED
Interferometry
Fizeau homogeneity test
Inhomogeneous material

38. 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