Description

The K-correlation scatter model is used to represent Power Spectral Density (PSD) measurements which can be fit to a specific algebraic form, namely a straight line on a log-log plot of PSD versus frequency.  For detailed information regarding the relationship between BSDF and the K-Correlation PSD, please refer to the reference paper below.

Dittman, Michael, K-correlation power spectral density & surface scatter model, Proc. SPIE Vol. 6291 (2006)

Navigation

This feature can be accessed by selecting K-Correlation (K Correlation Power Spectral Density) as the Scatter Type in the Create a new scatter model dialog box.

Controls

Application Notes

Functional form

The 2D K-Correlation scatter model is defined by the following:

The value of A is determined by low-frequency behavior. The parameter B is related to correlation length. C determines the rate of slope fall off of the PSD at high frequencies.

Scripting with the K-Correlation model

Subroutines

AddKCorrelationScatter YourScatter

InitKCorrelationScatter Scatterstructure

SetKCorrelationScatter IndexInScatterList, YourScatter

GetKCorrelationScatter IndexInScatterList, YourScatter

Data structure
T_KCORRELATIONSCATTER

Wavelen – (double) reference wavelength l in um.

DeltaN – (double) Refractive index difference between substrate and incident media.

Refl - Reflectance of substrate.

Sigma - RMS roughness (um) measured at frequencies from 0 to 1/l.

 B – (double) 2p times typical surface wavelength.

Slope – (double) Slope of PSD curve at large spatial frequencies.

Name - Scatter model name

Description - Scatter model description.

ApplyRefl – (Boolean) Applies the scatter model on reflection. Default is False.

ApplyTrans – (Boolean) Applies the scatter model on transmission. Default is False.

HaltIncident – (Boolean) Halts the incident ray. Default is False.

This example adds a K-Correlation Scatter model to the FRED file associated with this script.

Dim s As T_KCORRELATIONSCATTER
s.Name = K-correlation Example"
s.Description = "Sample from FRED documentation"
s.Wavelen = 0.6328

s.DeltaN = 2

s.Refl = 1

s.Sigma = 0.0015

s.B = 0.2
s.Slope = -2
s.ApplyRefl = true
s.ApplyTrans = true
s.HaltIncident = true
AddKCorrelationScatter s

This example sets the fourth Scatter model’s name to “K-correlation Example 2”, as long as that scatter model is a K-correlation model. It fails if it is any other scatter type.

Dim s As T_KCORRELATIONSCATTER
s.Name = "K-correlation Example 2"
SetKCorrelationScatter 4, s

This example gets the fourth Scatter model and prints its name, as long as that scatter model is a K-Correlation model. It fails if it is any other scatter type.

Dim s As T_KCORRELATIONSCATTER
GetKCorrelationScatter 4, s
Print s.Name

Related Topics

ABg – for polished surface scatter

Binomial - plane symmetric case of general Polynomial

Extended Harvey-Shack - shift variant form of the Harvey-Shack model

Extended Scripted - User-defined scattering function that allows manipulation of the scattered rays' polarization state

Flat Black Paint – specify Total Integrated Scatter (TIS)

Harvey-Shack – for polished surface scatter

Lambertian – for diffuse scatter

Phong – cosⁿ from specular

Polynomial - General polynomial with diffuse and Lorentzian component

Scripted - User-defined scattering function

Surface Particle (Mie) – for particulate contamination

Tabulated BSDF – measured BSDF data

Tabulated PSD – measured PSD data

References

Stover, John, Optical Scattering - Measurement and Analysis, second edition, ISBN 0-8194-1934-6 (hc), Chapter 4, Sec 4.5, pg. 103

Dittman, Michael, K-correlation power spectral density & surface scatter model, Proc. SPIE Vol. 6291 (2006)

Church, E.L., Takacs, P.Z., and Leonard, T.A., 1989, The prediction of BRDFs from surface profile measurements, Proc. SPIE 1165, 136-150