ASM Webinar Digital Microscopy for Materials Science

Transcription

1 Digital Microscopy Defined The term Digital Microscopy applies to any optical platform that integrates a digital camera and software to acquire images; macroscopes, stereomicroscopes, compound microscopes and confocal microscopes qualify. Nearly any optical system can be a digital microscope if it is equipped with a camera and software to display live and stored images with or without a computer.

2 The Digital Microscopy Evolution 1970 s: Expensive Mainframe Systems Used Video Cameras and Frame Grabbers with poor resolution Used hardware-based cards for convolution filters (sharpen, median, etc)

3 The Digital Microscopy Evolution 1980 s: Advent of PCs Still used Video Cameras and Frame Grabbers Used newly developed software tools for filters Microscope controls motorized functions of stage x-y, motorized focus control with autofocus Remote function of motorized controls was offered through software

4 The Digital Microscopy Evolution 1990 s: More Powerful PCs Go Mainstream Measurement, Classification, Batch Processing Tools Added Advanced microscopes controlled by PCs now Internal motor drives for focus, added control of tube prisms, lamp intensity control Introduction of dedicated digital cameras using SCSI and later Firewire interfaces; faster bus speeds improve performance

5 The Digital Microscopy Evolution 2000 s: Moore s Law Continues; Intelligent Microscopes, Digital Cameras Even more powerful computers at lower prices Digital Cameras with many more pixels replace Frame Grabbers (Firewire, USB) Intelligent Microscopes with coded, motorized features Talk to computers Dynamic field and aperture control, objective correlated speeds for stage and focus controls Remote operation with or without PC Systems developed that do not offer eyepieces

6 The Digital Microscopy Evolution 2010+: Widespread Acceptance of Digital Microscopy and Digital Cameras Computers and displays continue to get better; prices drop (Moore s Law) Extensive Metadata stored with images to re-create previous conditions megapixel cameras using Firewire and USB interfaces dominate Extensive software feature sets satisfy most needs Digital Microscopy becomes the new accepted normal (even though it s been around for decades) Logical extension adds 3D display (from many Z-Axis slices ); Common Logical extension adds X/Y translation (from many X/Y images); Stitching Surface analysis of images widely available across all platforms Surface Analysis (roughness, topography, classic metrology) 3D Analysis (volume, area) Grain Sizing, Phase Analysis, Particle Counting, Particle Distribution, More

7 How to Select a Microscope System for Your Application If Real Estate is Location, Location, Location then Microscope Choices are based on Resolution, Resolution, Resolution! For Resolution from tens of microns to millimeters, a macroscope or stereomicroscope is a good choice For Resolution in the micron range, a compound microscope is a good choice For Resolution in the nanometer range, a confocal microscope is a good choice Examples Phase Analysis may only require a macroscope or stereomicroscope Grain Size analysis usually requires a compound microscope since measurements are based on microns

8 Objectives Drive the Optical Bus R = 0.61 /NA (Rayleigh s Criteria) = Wavelength of light Short wavelengths (Blue) have better resolution than longer wavelengths (Red) Mag N.A. Resolution 4x um 10x um 20x um 40x um 60x um 100x um

9 Microscopic Analysis Methods Macro / Stereo Compound Confocal Profiler Object Properties Form / Measurement Visual inspection Documentation Material Properties Microstructure analysis Measurement Documentation Surface Properties 3D Surface Form Characterization of interaction with surrounding components Precision manufacturing

10 How to Select a Microscope System for Your Application Once the Resolution requirements on the microscope are met, select the appropriate camera Goal: to faithfully reproduce what the microscope Sees (eyes/eyepieces will always see more detail than the digital image) If Magnification is < 20x, more pixels help (5 megapixels or more) If Magnification is > 40X, more pixels don t hurt but will affect dynamic range Bigger pixels are better at separating structures that are gray from those almost as gray, but image won t have the resolution that smaller pixels have Sadly, there is no one camera to accomplish all tasks Goto numbers: 2.3 pixels needed to detect a point at any magnification Goto numbers: ~20-25 pixels needed to accurately measure area at any magnification See Michael Davidson s excellent Pixel Calculator at FSU.edu

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12 Materials Science Applications Roughness Metallurgy Microelectronics Micro Mechanics Solar Cells Coatings Corrosion Forensics Microlenses Tribology Planarity Plastics Semiconductor Transparent Layers Highly Reflective Super Smooth Super Rough And more µm

13 Dual Core Confocal/Interferometry Microscopes Surface Roughness Measurement is common in metrology, new in digital imaging; values are typically Ra (Area Roughness), but many more ISO measurements are possible Characterization of surfaces is possible from digital microscopes, to macroscopes to stereomicroscopes to compounds to confocals, on a single software platform Metallurgical (X/Y) measurements are also possible for standard materials science applications such as grain sizing, inclusion rating, phase analysis, and particle counting

14 Surface Metrology Surface interactions are critical to virtually all materials, devices, and applications: Friction (Tribology) Interfaces between differing materials Corrosion Applications range from R&D through production Basic metrology equipment requirements: Measure a wide range of surfaces Accurate (Precision, Stability, Matching) Fast Easy to use

15 Leica Dual Core 3D System components Digital Microdisplay synchronized with CCD camera No moving parts in the optics Long life LED color High speed Large Z scan range Combines Confocal and Interferometry Can also be used as a standard microscope Brightfield images can be overlaid on topography BW High res blue LED 460 nm white LED micro display

16 Bearing Surface Example NASA Confocal measurement of the surface of a ceramic bearing from space shuttle main engines, showing unique Rivermark pattern Patterns are similar to electrical discharge damage in isolating materials 3D image of bearing surface Thank you to Lewis Chip Moore NASA/MSFC/EM10 - Tribology Team

17 Basic surface analysis um um Contour plot of bearing with spherical component removed ASM Webinar Bearing Metrology µm NM NASA Advanced software allows surface features to be analyzed as a pattern, instead of as individual defects Pattern features provide insight into the possible causes ISO Height Parameters Sq µm Root mean square height Ssk -5.7 Skewness Sku 60.0 Kurtosis Sp µm Maximum peak height Sv 1.66 µm Maximum pit height Sz 2.36 µm Maximum height Sa µm Arithmetic mean height Surface parameters of flattened surface All furrow s are displayed. Maximum depth of furrow s : 1.14 µm Mean depth of furrow s : µm Mean density of furrow s : 2714 cm/cm2

18 Grain Size Example (ASTM E112, ISO 643:2003 JIS G )

19 Grain Size Results (ASTM E112)

20 Grain Size Report (ASTM E112)

21 Steel Inclusion Rating for Non-metallic Contaminant Measurement ASTM E45 DIN with K factors JK JIS 555 ISO 4967 EN 10247

22 Inclusions are Not Welcome! They are zones of weakness in a ductile steel matrix environment They are the nuclei of cracks both for fatigue and single load They are potential origins for corrosion attack The lower their content, the better The smaller they are, the better The more homogeneous they are distributed, the better

23 Inclusion Report for ASTM E45

24 Phase Analysis

25 Phase Analysis

26 Phase Analysis

27 Particle Sizing & Distribution including Nodularity and Porosity

28 Particle Sizing & Distribution Histogram

29 Particle Sizing & Distribution Report

30 Thank You for Attending! Any Questions?