optical profiler
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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, [email protected] 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