FFT-based tools for analyzing surface-process interactions and for advanced filtering

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3D Fourier Analysis

Mountains® 6 Optional Module

Power spectrum density (surfaces & profiles)

FFT Plot Editor for advanced filtering(surfaces & profiles)

Texture isotropy, directionality & periodicity (surfaces)

Autocorrelation and intercorrelationplots (surfaces and profiles)

Frequency spectrum (surfaces & profiles)

The Frequency Spectrum study displays an interactive plot

obtained by the Fast Fourier Transform (FFT). The following

parameters are calculated for any XY point on a surface:

Wavelength.

Angle.

Magnitude (amplitude) of the radius in decibels (log scale)

or length units (linear scale).

Phase.

Frequency Spectrum

See the wavelength, magnitude, phase and angle of each point on a surface in an interactive frequency spectrum plot

The study also displays an interactive plot of the wavelengths

that make up a profile and calculates the following

parameters:

Wavelength (key).

Magnitude (amplitude).

Phase.

Insignificant spectral lines can be filtered using a Hanning

window function.

Plot generated by the Graphical Study of Volume Parameters study

3D Fourier Analysis Mountains 6 Optional Module

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Motor cylinder surface with honing marks. The Frequency Spectrum study provides an interactive plot with a logarithmic scale

(left) or a linear scale (right). It calculates parameters for each point on the surface.

Microlens array. The Frequency Spectrum study also provides an interactive plot . It

calculates parameters for each wavelength tn the microlens array

surface.

Power spectrum density

See the intensity of each wavelength in an interactive PSD plot

The Power Spectrum Density study displays an interactive

plot with wavelength on the x axis and intensity (square of the

amplitude) on the y axis. The amplitude is shown for each

selected wavelength.

Glass surface before (left) and after (right) an acid attack (courtesy LNE)

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PSD plot (using the all directions method) of the glass surface before the acid attack.

PSD plot (using the all directions method) of the glass surface after the acid attack.

3D Fourier Analysis Mountains 6 Optional Module

The Texture Direction study analyzes the surface using the

Fourier transform and shows dominant surface directions on

a polar or Cartesian plot. It calculates the following

parameters:

Isotropy (%). This is equal to the ISO 25178 Str parameter.

It is calculated with smoothing and with minimum and

maximum frequency thresholds of 5% and 80% respectively.

These thresholds can be changed by the user. The higher the

isotropy percentage value the more the surface resembles

itself in every direction.

The three most dominant lay directions of a surface (in

degree units).

Isotropy, directionality and periodicity

View dominant surface directions and calculate isotropy and other parameters

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Nanoscopic wires

The Texture Isotropy study displays the 2D autocorrelation

plot after form removal and calculates the following

parameters with respect to a user-defined threshold (default

0.2):

Isotropy (%)

Periodicity (%).

Period (length).

Direction of the period (degrees).

Texture Direction study:

isotropy and dominant directionsAutocorrelation plot

Roughness reference standardTexture Isotropy study

isotropy and periodicityAutocorrelation plot

The Autocorrelation operator displays a 3D autocorrelation

plot. The plot helps to distinguish between isotropic surfaces

(with a circular central node) and anisotropic surfaces (with a

central node extended along one direction).

The Intercorrelation operator displays an intercorrelation

plot. .

3D Fourier Analysis Mountains 6 Optional Module

FFT plot editor

Carry out advanced filtering, remove noise

The FFT plot editor (incorporated in two Filtering of the FFT

operators) is used for advanced filtering. You can use

thresholding to remove frequencies or exclude wavelengths

interactively.

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The FFT plot can be edited interactively in

order to eliminate wavelengths responsible for

artifacts.

Alumina surface topography

after using the FFT plot editor

to remove the artifacts.

Alumina surface topography

(8.75 µm x 8.75 µm x 308 nm)

measured by AFM.

The lines running from left to

right are scanning artifacts.

3D Fourier Analysis Mountains 6 Optional Module

Selected features

Mountains® 6 3D Fourier Optional Module

Frequency spectrum • Display interactive frequency spectrum plot.

• Display wavelength, angle, amplitude and phase of a selected XY point on a surface.

• Display amplitude and phase of a selected wavelength on a profile.

• Apply Hanning window function to eliminate insignificant spectral lines.

Power spectrum density (PSD) • Calculate the PSD using the horizontal or all directions method.

• Display interactive PSD plot with wavelength on the x axis and intensity (square of the amplitude) on the

y axis.

• Display the amplitude of a selected wavelength.

• Apply Hanning window function.

Isotropy, directionality and periodicity • Calculate isotropy (%) with default minimum and maximum thresholds (in which case it is equivalent to

the Str parameter) or user-defined thresholds.

• Display dominant surface directions on a direction rose.

• Calculate periodicity (%), period (length), and direction of the period (degrees).

Autocorrelation and intercorrelation • 3D autocorrelation plot.

• 3D intercorrelation plot.

FFT plot editor • Remove frequencies using thresholding or exclude wavelengths interactively.

Digital Surf Head Office and R&D Center

Digital Surf SARL, 16 rue Lavoisier, 25000 Besançon, France

Tel +33 3 81 50 48 00 Fax +33 3 81 50 92 24

contact@digitalsurf.fr www.digitalsurf.com

© 1996-2011 Digital Surf SARL. All rights reserved.

Specifications subject to change without prior notice

Mountains 6 - 3D Fourier Analysis Optional Module3D Fourier Analysis Mountains 6 Optional Module