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PRESENTED BYSANDEEP NAIR CB.EN.P2MFG15018M.TECH- MFGSurface Properties - Measurement TechniquesProfilometer

AMRITA SCHOOL OF ENGINEERING , COIMBATORE (TAMIL NADU)

CONTENTSIntroductionTypes of ProfilometerContact Non - ContactWorking PrincipleOptical Principle BasicsModes of OperationSystem PerformancesRange , Resolution & AccuracySurface ParametersSurface Topography & Amplitude ParametersProfilometers @ amritaMeasurement Examples

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INTRODUCTIONDefinition. - Aprofilometeris a device used to measure the roughness of a surface.- Gives difference between the high and low point of a surface in nanometres.

Types of Profilometers.

Non - Contact ProfilometersContact Profilometers

NON - CONTACT PROFILOMETEROptical Methods Vertical Scanning Interferometry Phase - Shifting Interferometry Differential Interference Contrast Microscopy

Focus Detection Methods Intensity Detection Focus Variation Differential DetectionCritical AngleAstigmatic Method Focault Method Confocal Microscopy Contd

NON - CONTACT PROFILOMETERPattern Projection Methods Fringe ProjectionFourier ProfilometryMoire

CONTACT & PSEUDO CONTACT PROFILOMETERStylus ProfilometerAtomic Force MicroscopyScanning Tunneling Microscopy

CONTACT PROFILOMETER

Height from 10 nanometres to 1 millimetreRadius of diamond stylus from 20 nm to 25 mHorizontal resolution is controlled by the scan speed and data signal sampling rate.

CONTACT PROFILOMETERAdvantages & Disadvantages

Acceptance & Easy to UseSurface IndependenceResolution : The stylus tip radius can be as small as 20 nanometres Direct Technique : No modelling required. Not suitable for very soft (or even liquid) and easily damageable surface Very hard and damage surface can damage the stylus. Only 2D

NON - CONTACT PROFILOMETER

Uses beams of light to read a surfaceThey shoot a beam out and measure the time it takes to return. no wear since none of its parts touch anything

TWYMANGREEN INTERFEROMETERUses beams of light to read a surfaceThey shoot a beam out and measure the time it takes to return. no wear since none of its parts touch anything

NON - CONTACT PROFILOMETER

ADVANTAGES OF OPTICAL PROFILOMETERS

Good Resolution: Vertical resolution is usually in the nm level

High Speed

Reliability : cannot be damaged by surface wear or careless operators

Spot size or lateral resolution ranges from a few micrometres down to sub micrometre. Contd

NON - CONTACT PROFILOMETER

LIMITATIONS:

Limited by very high slopes, where the light is reflected away from the objective, unless the slope has enough texture to provide the light.

Surface Modelling is required to convert the digital code to human usable data.

Working Principle of Profilometer (Non - Contact Optical Profilometer)

Working Principle of Profilometer(Non - Contact Optical Profilometer)

A light beam is split, reflecting from reference (known/flat) & test material.

Constructive and destructive interference occurs

Forms the light and dark bands known as interference fringes.The optical path differences are due to height variances in the test surface.Contd

Working Principle of Profilometer(Non - Contact Optical Profilometer)Constructive interference areas as lighter and the destructive interference areas as darker.

Interference ImageLight to dark fringes above represents one-half a wavelength of difference between the reference path and the test path. Contd

Working Principle of Profilometer(Non - Contact Optical Profilometer)From the above Interference Image:

Lower portion is out of focus means less interference. Greatest contrast means best focus. MODES OF OPERATIONPhase Shifting Interferometry (PSI) ModeVertical Scanning Interferometry (VSI) Mode

MODES OF OPERATION(Non - Contact Optical Profilometer)

DEVELOPMENT IN OPTICAL PROFILER

SYSTEM PERFORMANCESRange: Highest vertical distance the profiler can measure.

Resolution: Smallest distance the profiler can accurately measure.

Lateral Resolution Vertical Resolution

Accuracy: How closely a measured value matches the true value & can be obtained by frequent calibration.

SURFACE PARAMETERSSurface Topography: 3D representation of geometric surface irregularities

SURFACE PARAMETERSRoughness : Closely spaced irregularities

Waviness : More widely spaced irregularities

Error of Form : Long period & non cyclic deviations

Flaws : Discrete & infrequent irregularities

Roughness & Waviness comprise the Surface Texture

PROFILOMETERS @ AMRITA

Taylor Hobson TalysurfTraverse length:0.1 - 50mmTraverse speed:10mm/s maxStraightness error:0.4um over 50mmGauge range/resolution:16nm@1mm, 3nm@0.2mm range

Features include:Large 50mm horizontal traverseFlexible configuration to meet your needsPowerful software options - including Form, Contour, Dual Profile and Gothic ArchIntuitive menu structure

MEASUREMENT EXAMPLESSurface of steel Block

3D ImageReflection Intensity

MEASUREMENT EXAMPLESPit on a thin iron plate

2D image Plate thickness 0.7mm(Depth 0.14494mm)

MEASUREMENT EXAMPLES3D image

REFERENCES

Research Papers :

T.V.Vorburger, J.Raja. Surface Finish Metrology Tutorial June 1990 WYKO Surface Profilers Technical Reference manual September 1999, Version 2.2.1

Webpage

Profilometer, Wikipedia http://en.wikipedia.org/wiki/Profilometer

THANK YOU