Surface Metrology Group

Transcription

1 Surface Metrology Group

2 The History of the Group The Surface Metrology Group was formally the Centre for Metrology at the University of Birmingham

3 History of SMG (1996) The Nanometrology Laboratory Project ( Huddersfield) University of Huddersfield Huddersfield Pride (ERDF) SRIF (HEFCE infrastructure Fund) Taylor Hobson Limited

4 Nanometrology Laboratory Precision dimensional Metrology Nano scale Surface Metrology Ultra Precision Manufacturing

5 Facilities: Nano Lab Active anti-vibration system (0.3 Hz) Environmental Contents Temperature 20 o C +/- 0.5 o C, 0.3 o Cat gauging point Cleanliness Humidity Vibration Lighting Class J 45% +/- 10% around the regulated temperature of 20 o C Defined by block spec 750 lux at bench level of reading surface Reaction Mass Semi Active anti-vibration system

6 Facilities: Optical Lab

7 Facilities: Main Surface & Dimensional Metrology Veeco Atomic Force Microscope Wyko Optical Interferometer TH Roundness Measurement Machine Fisba Optik Phase Shifting Interferometer TH Coherence Correlation Interferometer TH Precision Contacting Stylus Zeiss PRISMO Access CMM Mitutoyo CMM

8 Facilities: New Dimensional Metrology The University has invested 0.5m to build a CT centre together with a high power computing centre

9 Main Research Directions Based around four areas of research in EPSRC Theme II Surface & Dimensional Measurement Mathematics for Metrology Micro and Nano Scale Surface Instrumentation Ultra Precision Surface Manufacturing MEMS/MST Wafer/ Hard Disc Biomedical Implants Stainless Steel and Aluminium Sheet Cylinder liners New Mathematicsbased Analysis Theory Statistics-based Characterisation Technology Practical application Methods For: Algorithms Software ISO areal standard Exploration of Measurement Principles for Next Generation Optical Interferometer Metrology for Precision Polishing of Metals and Ceramics for Implants

10 Surface Characterisation Honed Ground Polished Hand Polish EDM Superpolished

11 Surface Characterisation Grinding wheel surface Steel sheet surface Biological surface Diamond turned optical surface

12 Surface Characterisation F Theta Lens Off axis Mirrors Focusing lens Triangular prisms Hexagonal prisms Micro lens Mould

13 Freeform Surface Characterisation Astronomy Nuclear Physics Airspace Implants Primary mirror (42m) (Mirror segment 1.4 m)

14 The Replacement Knee Joint Patella Femur Femoral component Polythene bearing surface Tibial plate Tibia (Courtesy of DePuy UK)

15 Filtration: Partial differential equation

16 Industrial Application Implant Initial residual surface mesh t=0 Diffused residuals at t =0.0113, c =0.8 mm. Diffused residuals at t =0.1100, c =2.5 mm.

17 Numerical Parametric Techniques ISO Part 2: Field parameters Peak/valley heights Surface slopes Peak spacing Valley volumes

18 How to Evaluate Structured Surfaces? Ra Ground? Characterisation of structured surfaces From: Statistics of a data set To : Statistics of predefined surface features Hexagonal prisms

19 Numerical Parametric Techniques:

20 Filtration: Non linear differential equation Non- Linear diffusion equation um Measure profile Denoised profile mm Step height um Measured profile Denoised profile mm Aspheric diffractive lens 2t MEMs surfaces

21 Mathematical for Metrology Filtration Approximation Spectral Methods PDE based smoothing Inverse Challenges The inverse problem is to compute either the input or the system, given the other two quantities Morphological Segmentation

22 Areal Surface Characterisation Mathematical Models to Predict Surface Performance Diagnose the Manufacturing Process Stable Cutting Heavy Chatter Predict and Analysis Surface Performance

23 surface texture design and measurement Chain link number Geometrical characteristic of feature Product documentatio n indication Codification Definition of tolerances Theoretical definition and values Example Surface Texture ISO 1302 ISO 4287, 11562,12085, Roughness , 2, 3 Profile (ISO) Definitions for actual feature characteristic or parameter ISO 4287, 11562, 12085, Assessment of the deviations of the workpiece Comparison with tolerance limits Measurement equipment requirements Calibration requirements Measurements standards ISO 4288,12085 ISO 3274, ISO 5436, Waviness ISO 1302 ISO 4287,11562, ISO 11562, ISO 4288, ISO 3274, ISO 5436, Primary ISO 1302 ISO 4287,11562 ISO 4288 ISO 3274, Areal (ISO) ISO (D) ISO (D) ISO (D) ISO , 601, 602, 603(D), 604(D), 605(D) ISO (D), 701, 702(D), 703(D)

24 Design/Specification: Integrated into CAD design system

25 Go to ISO Geometrical Specifications system for surface texture design Insert the surface texture callout

26 Optical Instrument Research Measurement Challenges are: No removal from a machine tool/production line; With affordable manufacturing costs; Accessible into manufacturing environment, with regard to online, non contact, high speed, ease of use, small footprint and robustness; Reaching the same level of accuracy as the state of the art laboratory based measurement systems. Optical Research Focuses on: Create new measurement principles; Provide the enabling techniques for further instrumentation.

27 Physical Principles Tech I: Wavelength tuning Tech II: Self compensating common path structures Tech III: Wavelength dispersive multiplexing Tech IV: Wavelength absolute measurement Tech V: Hybrid photonics microsystems Tech VI: Dispersed reference interferometry

28 Integrated Optic Chip Interferometer Concept Integrated Optic Chip Interferometer Interferometry Widespread applications for surface profiling at high resolutions. Hybrid photonics Miniaturises the optics required for interferometry. Fully miniaturised measurement system Providing more scope for integrated metrology on machine tools.

29 Integrated Optic Chip Interferometer Target Specification: Single Point/Profile Measurement Measurement Rate (> 300 Hz) High vertical resolution (< 1 nm) Profile Mode Long vertical range (several mm) Single Point Mode Miniaturised Full Measurement System Environmentally Robust

30 Novel Measurement Techniques Tech I&II&(III/IV)&V: Chip Optical Interferometer

31 Integrated Optic Chip Interferometer Physical Structure Current Version Package Dimensions: 100 x 50 x 22 mm Thermally stabilised with a Peltier element

32 Dispersive White Light Interferometer Objectives High Dynamic Range Single Point Measurement Very Fast (>10 khz) High vertical resolution (< 1 nm) Good vertical range (4 5 mm) Remote Probe/Multi Probe

33 Dispersive White Light Interferometer Fibre/Multi Probe System Schematic Mirror PZT Mirror Dispersive Element Beam Splitter GRIN Lens 3dB Coupler SLD λ=800 nm GRIN Lens (uncoated) l l c Diffraction Grating Surface PC Collimating Lens CCD Line Array Common mode fibre linked Fizeau probe. Multi-sensor capability using optical switching Unbalanced interrogation interferometer acts as a coherence discriminator. Multi probe potential using optical switches.

34 Dispersive White Light Interferometer Example Bulk Optic Apparatus SLED light source supplies moderately wide bandwidth with good spatial coherence. Dispersive element in one arm CCD spectrometry detects the fringes formed across the band.

35 Dispersive White Light Interferometer Theoretical Range = 569 µm Resolution = 279 nm Linearity = 0.842% over 100 µm Measurement rate = 20 Hz Paper accepted to CIRP Annals

36 Wavelength Scanning Interferometer Tech I&II&IV Spectral Scanning Interferometer

37 WSI - Operating Principle Acousto-optic tuneable filter (AOTF) tunes the wavelength from nm. No moving parts. During the wavelength scanning, images are captured with a high speed CCD camera, frames. Captured Frames 200 Single Pixel Result Frequency determines height interference intensity iteration of Frame wavelength Number scanning

38 WSI Prototype Prototype: Measurement head separated from the scanned light source Piezo based stabilisation implemented in the reference arm. Motorised stage: 2 linear axes, 2 rotating. Configurable for highly angle structures.

39 Potential Measurement Systems Combining Techs I VI can create: Fibre Surface Interferometer Chip Optical Interferometer Spectral Scanning Interferometer Dispersive white-light Interferometer Profile measurement Single point/profile measurement Full field measurement Single point measurement Sub-nanometre vertical resolution Measurement time <1 second Lateral range of 7 mm Small remote mountable probe head Output power > 5 mw Tuning range 100 nm Tuning period < 3 ms Tuning resolution < 10 pm Fully integrated device in a single small package Measurement interval < 0.5 sec Nanometre resolution over 300 µm vertical range Fibre linked compact probe Fast >10 khz readout rate 5 mm Measurement Range Sub-nanometre resolution Multi-probing

40 Research Achievements and Future Applications Patents and Papers Future Applications Prototype Instruments Dispersive white-light Interferometer Spectral Scanning Interferometer Return spring Gain block Electrical leads for Fibre pigtail Thermistor thermistor, cooler and laser current source Aluminium block Thermoelectric cooler 'SQUIGGLE' motor Lever arm PCB for motor control Chip Optical Interferometer

41 FP7 Project: Co ordinated by Prof. Liam Blunt Defect Detection for flexible CIGS Photovoltaics CIGS flexible photovoltaic cell structure Sensor will form part of a hybrid system, combined with machine vision to provide enhanced defect characterisation.

42 Applications FP7 NanoMend will tailor its technology to the specific needs of the following applications: Flexible solar modules The food packaging

43 Example of defects in CPI barrier substrate Holes in 40nm ALD Al 2 O 3 film about 60 µm lateral dimension SEM picture Roughness excluding defects ~0.6nm

44 EPSRC Grant: Dr. Feng Gao Based on white light spectral interferometry Combine with GP GPU and high speed digital camera technologies that advanced in recent years

45 EPSRC Grant: Dr. Feng Gao Reference mirror Halogen bulb Iris diaphragm Cylindrical lens Focusing lens Pin hole Collimator Filter Collimator Beam splitter Measured surface Frame grabber CCD Fibre coupler lens Compressor objective Focusing lens Optical fibre path cable Fold mirror Slit Diffraction grating Computer Schematic diagram of the optical setup

46 White light source CCD camera Linnik interferometer Experimental optical setup

47 EPSRC Fellowship: Prof. Paul Scott Geometrical Variability Tolerance Zone defined from traditional metrology era Slip Gauges S Sine bar L Surface Plate Sin( ) = S/L Traditional Metrology (after Rolt) Digital Paradigm How to define new Tolerance System for current era requirements?

48 Example: Problems Design specification of leading edge Reality verification of leading edge Loosening of Cup

49 Summary Publishing Authoritive Papers, Books and Techniques