Lecture-3%20Optical%20Microscopy

1
Lecture-3 Optical Microscopy

• Introduction
• Lens formula, Image formation and Magnification
• Resolution and lens defects
• Basic components and their functions
• Common modes of analysis
• Specialized Microscopy Techniques
• Typical examples of applications

http//www.youtube.com/watch?vP2teE17zT4IlistPL
KstG-8VPWKzOe4TkvA7F6qMlG2HH8meX at046-133
2
Review Problems on Optical Microscopy
1. Compare the focal lengths of two glass
converging lenses, one with a larger curvature
angle and the other with a smaller curvature
angle.   2. List the parameters that affect the
resolution of optical microscopes. 3. A student
finds that some details on the specimen cannot be
resolved even after the resolution of the
microscope was improved by using the oil
immersion objective. The student thinks that the
details can be resolved by enlarging a photograph
taken with the microscope at maximum
magnification. Do you agree? Justify your answer.
http//www.doitpoms.ac.uk/tlplib/optical-microscop
y/questions.php
3
Resolution of a Microscope (lateral)
http//micro.magnet.fsu.edu/primer/java/microscopy
/immersion/index.html
The smallest distance between two specimen points
that can still be distinguished as two separate
entities dmin 0.61l/NA NAnsin(?)
l illumination wavelength (light) NA
numerical aperture ?-one half of the objective
angular aperture n-imaging medium
refractive index
dmin 0.3?m for a midspectrum l of 0.55?m
https//www.youtube.com/watch?vn2asdncMYMo
at535-600
4
Numerical Aperture (NA)
NA1 - theoretical maximum numerical aperture of
a lens operating with air as the imaging medium
NA n(sin ?)
n refractive index of the imaging medium between
the front lens of objective and specimen cover
glass
Objective lens
Angular aperture
(?72 degrees)
?
One half of A-A
Specimen cover glass
NA of an objective is a measure of its ability to
gather light and resolve fine specimen detail at
a fixed object distance.
https//en.wikipedia.org/wiki/Angular_aperture
http//micro.magnet.fsu.edu/primer/java/microscop
y/immersion/index.html
5
Numerical Aperture
NA n(sin ?)
Imaging Medium
Air n1.0
Immersion oil n1.515
http//www.youtube.com/watch?vRSKB0J1sRnU oil
immersion objective use in microscope at033
6
Axial resolution Depth of Field
Depth of focus (f mm)
Depth of Field Ranges (F ?m)
(F mm)
NA f F 0.1 0.13 15.5 0.4 3.8 5.8 .95
80.0 0.19
The distance above and below geometric image
plane within which the image is in focus
The axial range through which an object can be
focused without any appreciable change in
image sharpness
M NA f F M NA f F
F is determined by NA.
http//www.matter.org.uk/tem/depth_of_field.htm ht
tp//www.youtube.com/watch?vFvC2WLUqEug
at340
7
Depth of Focus
The distance above and below geometric image
plane within which the image is in focus.
Depth of focus (f mm)
CCD camera
8
Axial resolution Depth of Field
The axial range through which an object can be
focused without any appreciable change in image
sharpness.
Depth of focus (f mm)
NA f F 0.1 0.13 15.5 0.4 3.8 5.8 .95
80.0 0.19
25?m
Small F Large F
9
Basic components and their functions
http//www.youtube.com/watch?vRKA8_mif6-E Microsc
ope Review (simple, clear) http//www.youtube.com
/watch?vb2PCJ5s-iyk Microscope working in
animation (How to use a microscope) http//www.yo
utube.com/watch?annotation_idannotation_100990fe
atureivsrc_vidL6d3zD2LtSIvntPjuUMdXbg (I)
http//www.youtube.com/watch?vVQtMHj3vaLg
(II) Parts and Function of a Microscope
(details) http//www.youtube.com/watch?vX-w98KA8
UqUfeaturerelated How to use a microscope
(specimen preparation at155-230) http//www.yo
utube.com/watch?vbGBgABLEV4g How to care for and
operate a microscope
10
Basic components and their functions
(1) Eyepiece (ocular lens) (2) Revolving nose
piece (to hold multiple objective lenses) (3)
Objective lenses (4) And (5) Focus knobs
(4) Coarse adjustment (5) Fine
adjustment (6) Stage (to hold the specimen) (7)
Light source (lamp) (8) Condenser lens and
diaphragm (9) Mechanical stage (move the
specimen on two horizontal axes for positioning
the specimen)
11
Functions of the Major Parts of a Optical
Microscope

• Lamp and Condenser project a parallel beam of
  light onto the sample for illumination
• Sample stage with X-Y movement sample is placed
  on the stage and different part of the sample can
  be viewed due to the X-Y movement capability
• Focusing knobs since the distance between
  objective and eyepiece is fixed, focusing is
  achieved by moving the sample relative to the
  objective lens

12
Light Sources
13
Condenser
Light from the microscope light source
Condenser gathers light and concentrates it into
a cone of light that illuminates the specimen
with uniform intensity over the entire viewfield
http//www.youtube.com/watch?annotation_idannotat
ion_100990featureivsrc_vidL6d3zD2LtSIvntPjuU
MdXbg 808 to 940 http//micro.magnet.fsu.edu/p
rimer/java/kohler/contrast/index.html
14
Specimen Stage
http//micro.magnet.fsu.edu/primer/flash/stage/ind
ex.html
15
Functions of the Major Parts of a Optical
Microscope

• Objective does the main part of magnification
  and resolves the fine details on the samples (mo
  10 100)
• Eyepiece forms a further magnified virtual image
  which can be observed directly with eyes (me
  10)
• Beam splitter and camera allow a permanent
  record of the real image from the objective be
  made on film (for modern research microscope)

16
Olympus BX51Research Microscope Cutaway Diagram
camera
Beam splitter
Reflected light
Transmitted light
http//micro.magnet.fsu.edu/primer/java/microassem
bly/index.html
17
Objective Lens
dmin 0.61l/NA
Anatomy of an objective
Objective specifications
rical ture
DIC-differential interference contrast
Objectives are the most important components of
a light microscope image formation,
magnification, the quality of images and the
resolution of the microscope
http//www.youtube.com/watch?vP0Z4H2O_Stg
Objectives to526 http//www.youtube.com/watch
?vH8PQ9RMUoA8 Grades of objectives to230
325-450 https//www.youtube.com/watch?vFwBjpi8c
k1Y Alignment of OM
18
Defects in Lens

• Curvature of Field - When visible light is
  focused through a curved lens, the image plane
  produced by the lens will be curved
• The image appears sharp and crisp either in the
  center or on the edges of the viewfield but not
  both

http//micro.magnet.fsu.edu/primer/java/aberration
s/curvatureoffield/index.html
19
Defects in Lens

• Chromatic Aberration
• Axial - Blue light is refracted to the greatest
  extent followed by green and red light, a
  phenomenon commonly referred to as dispersion
• Lateral - chromatic difference of magnification
  the blue image of a detail was slightly larger
  than the green image or the red image in white
  light, thus causing color ringing of specimen
  details at the outer regions of the field of view

A converging lens can be combined with a weaker
diverging lens, so that the chromatic aberrations
cancel for certain wavelengths The combination
achromatic doublet
weaker diverging lens
http//www.youtube.com/watch?vyH7rbRu7Av8listPL
02D1D436A44B521A chromatic
aberration http//www.youtube.com/watch?vH8PQ9RMU
oA8 at330-430
20
Eyepiece Lens
(Diaphragm)
M(L/fo)(25/fe)
Eyepieces (Oculars) work in combination with
microscope objectives to further magnify the
intermediate image
http//micro.magnet.fsu.edu/primer/anatomy/oculars
.html http//www.birdwatching.com/optics/diopter_s
et.html
21
Lecture-3 Optical Microscopy

• Introduction
• Lens formula, Image formation and Magnification
• Resolution and lens defects
• Basic components and their functions
• Common modes of analysis
• Specialized Microscopy Techniques
• Typical examples of applications

22
Common Modes of Analysis
Depending on the nature of samples, different
illumination methods must be used

• Transmitted OM - transparent specimens
• thin section of rocks, minerals and single
  crystals
• Reflected OM - opaque specimens
• most metals, ceramics, semiconductors
• Specialized Microscopy Techniques
• Polarized LM - specimens with anisotropic
  optical
• character
• Characteristics of materials can be determined
• morphology (shape and size), phase distribution
  (amorphous or crystalline), transparency or
  opacity, color, refractive indices, dispersion of
  refractive indices, crystal system,
  birefringence, degree of crystallinity,
  polymorphism and etc.

23
Anatomy of a modern OM
http//www.youtube.com/watch?v7-Tlyd7piSM
Trans OM to137 Refle OM from 138-end
Illumination System
Reflected OM
Transmitted OM
Illumination System
http//www.youtube.com/watch?vzq13e36cs3s
at020-140 Field diaphragm
24
Olympus BX51Research Microscope Cutaway Diagram
camera
Beam splitter
http//micro.magnet.fsu.edu/primer/java/microassem
bly/index.html
25
Common Modes of Analysis
Depending on the nature of samples, different
illumination methods must be used

• Transmitted OM - transparent specimens
• thin section of rocks, minerals and single
  crystals
• Reflected OM - opaque specimens
• most metals, ceramics, semiconductors
• Specialized Microscopy Techniques
• Polarized LM - specimens with anisotropic
  optical
• character
• Characteristics of materials can be determined
• morphology (shape and size), phase distribution
  (amorphous or crystalline), transparency or
  opacity, color, refractive indices, dispersion of
  refractive indices, crystal system,
  birefringence, degree of crystallinity,
  polymorphism and etc.

26
Polarized Light Microscopy
Polarized light microscope is designed to observe
specimens that are visible primarily due to their
optically anisotropic character (birefringent).
The microscope must be equipped with both a
polarizer, positioned in the light path somewhere
before the specimen, and an analyzer (a second
polarizer), placed in the optical pathway between
the objective rear aperture and the observation
tubes or camera port.
birefringent - doubly refracting
27
Polarization of Light
http//www.youtube.com/watch?vrbx3K1xBxVU
polarized light
When the electric field vectors of light are
restricted to a single plane by filtration, then
the the light is said to be polarized with
respect to the direction of propagation and all
waves vibrate in the same plane.
http//www.youtube.com/watch?vlZ-_i82s16Efeature
endscreenNR1 to330min http//www.youtube.c
om/watch?vE9qpbt0v5Hw
http//micro.magnet.fsu.edu/primer/java/polarizedl
ight/filters/index.html
28
Birefringence
Birefringence is optical property of a material
having a refractive index that depends on the
polarization and propagation direction of light.
Isotropic
anisotropic
CaCO3
Double Refraction (Birefringence)
Anisotropic
http//www.youtube.com/watch?vWdrYRJfiUv0
29
(Birefringence)
Anisotropic Optical Character
a
Cubic
Crystals are classified as being either isotropic
or anisotropic depending upon their optical
behavior and whether or not their
crystallographic axes are equivalent. All
isotropic crystals have equivalent axes that
interact with light in a similar manner,
regardless of the crystal orientation with
respect to incident light waves. Light entering
an isotropic crystal is refracted at a constant
angle and passes through the crystal at a single
velocity without being polarized by interaction
with the electronic components of the crystalline
lattice.
tetragonal
c
a
Anisotropic crystals have crystallographically
distinct axes and interact with light in a
manner that is dependent upon the orientation of
the crystalline lattice with respect to the
incident light. When light enters the optical
axis (c) of anisotropic crystals, it acts in a
manner similar to interaction with isotropic
crystals and passes through at a single velocity.
However, when light enters a non-equivalent axis
(a), it is refracted into two rays each polarized
with the vibration directions oriented at right
angles to one another, and traveling at different
velocities. This phenomenon is termed "double" or
"bi" refraction and is seen to a greater or
lesser degree in all anisotropic crystals.
http//micro.magnet.fsu.edu/primer/java/polarizedl
ight/crystal/index.html
30
Polarized Light Microscopy
Polarized light microscope is designed to observe
specimens that are visible primarily due to their
optically anisotropic character (birefringent).
The microscope must be equipped with both a
polarizer, positioned in the light path somewhere
before the specimen, and an analyzer (a second
polarizer), placed in the optical pathway between
the objective rear aperture and the observation
tubes or camera port.
birefringent - doubly refracting
31
Polarized Optical Microscopy (POM)
Reflected POM Transmitted POM

1. Surface features of a microprocessor integrated
   circuit
2. Apollo 14 Moon rock

http//micro.magnet.fsu.edu/primer/virtual/polariz
ing/index.html
32
Common Modes of Analysis
Depending on the nature of samples, different
illumination methods must be used

• Transmitted OM - transparent specimens
• thin section of rocks, minerals and single
  crystals
• Reflected OM - opaque specimens
• most metals, ceramics, semiconductors
• Specialized Microscopy Techniques
• Polarized LM - specimens with anisotropic
  optical
• character
• Characteristics of materials can be determined
• morphology (shape and size), phase distribution
  (amorphous or crystalline), transparency or
  opacity, color, refractive indices, dispersion of
  refractive indices, crystal system,
  birefringence, degree of crystallinity,
  polymorphism and etc.

http//www.youtube.com/watch?vulNZ3u7_J5I to
105
http//www.youtube.com/watch?vIw734z1e6wQ
to130
33
Lecture-3 Optical Microscopy

• Introduction
• Lens formula, Image formation and Magnification
• Resolution and lens defects
• Basic components and their functions
• Common modes of analysis
• Specialized Microscopy Techniques
• Typical examples of applications

34
Specialized OM Techniques

• Enhancement of Contrast
• Darkfield Microscopy
• Phase contrast microscopy
• Differential interference contrast microscopy
• Fluorescence microscopy-medical organic
  materials
• Scanning confocal optical microscopy (relatively
  new)
• Three-Dimensional Optical Microscopy
• inspect and measure submicrometer features in
  semiconductors and other materials
• Hot- and cold-stage microscopy
• melting, freezing points and eutectics,
  polymorphs, twin and domain dynamics, phase
  transformations
• In situ microscopy
• E-field, stress, etc.
• Special environmental stages-vacuum or gases

35
Contrast
http//micro.magnet.fsu.edu/primer/techniques/cont
rast.html
Contrast is defined as the difference in light
intensity between the specimen and the adjacent
background relative to the overall background
intensity.
Image contrast, C is defined by
Sspecimen-Sbackgroud ?S C
Sspecimen
SA Sspecimen (Smax) and Sbackgroud (Smin) are
intensities measured from specimen and
background, e.g., A and B, in the scanned
area. Cminimum 2 for human eye to distinguish
differences between the specimen (image) and its
background.
http//www.youtube.com/watch?vSVK4OkUK0Yw at147
-304
36
Contrast in Optical Microscope
https//www.youtube.com/watch?vL3SsxIUm0As
at217-346 Interaction of light with matter
Contrast produced in the specimen by the
absorption of light (directly related to the
chemical composition of the absorber) and the
predominant source of contrast in the ordinary
optical microscope, brightness, reflectance,
birefringence, light scattering, diffraction,
fluorescence, or color variations have been the
classical means of imaging specimens in
brightfield microscopy.
Enhancement of contrast by darkfield microscopy
Darkfield microscopy is a specialized
illumination technique that capitalizes on
oblique illumination to enhance contrast in
specimens that are not imaged well under normal
brightfield illumination conditions.
http//micro.magnet.fsu.edu/primer/virtual/virtual
zoo/index.html
http//www.youtube.com/watch?vP2teE17zT4IlistPL
KstG-8VPWKzOe4TkvA7F6qMlG2HH8meX at133-221
37
Angle of Illumination
http//www.youtube.com/watch?vd6jsnLIsNwI
at340-520

• Bright filed illumination The normal method of
  illumination, light comes from above (for
  reflected OM)
• Oblique illumination light is not projected
  along the optical axis of the objective lens
  better contrast for detail features
• Dark field illumination The light is projected
  onto specimen surface through a special mirror
  block and attachment in the objective the most
  effective way to improve contrast.

Light stop
Imax-Imin
Imax
C
Imax
Imin
C-contrast
http//www.youtube.com/watch?v7V3nyRGeha4
Dark field microscopy http//micro.magnet.fsu.edu
/primer/techniques/darkfieldreflect.html
38
Condenser
Oblique hollow cone of light
Cone of light
Reflected light
Light stop
Bright field illumination
Dark field illumination
Condenser gathers light and concentrates it into
a cone of light that illuminates the specimen
with uniform intensity over the entire viewfield.
39
Transmitted Dark Field Illumination
http//micro.magnet.fsu.edu/primer/java/darkfield/
cardioid/index.html http//micro.magnet.fsu.edu/pr
imer/techniques/darkfieldreflect.html reflected
DF
Oblique rays
specimen
Reflected beam
I
I
Parallel beam
distance
distance
http//www.youtube.com/watch?vI4ZQm-CAgL8
at524-814 http//www.youtube.com/watch?vJ2e0x7
iTqTU DF and BF images
40
Contrast Enhancement
OM images of the green alga Micrasterias
41
Specialized OM Techniques

• Enhancement of Contrast
• Darkfield Microscopy
• Phase contrast microscopy
• Differential interference contrast microscopy
• Fluorescence microscopy-medical organic
  materials
• Scanning confocal optical microscopy (relatively
  new)
• Three-Dimensional Optical Microscopy
• inspect and measure submicrometer features in
  semiconductors and other materials
• Hot- and cold-stage microscopy
• melting, freezing points and eutectics,
  polymorphs, twin and domain dynamics, phase
  transformations
• In situ microscopy
• E-field, stress, etc.
• Special environmental stages-vacuum or gases

42
Phase Contrast Microscopy
http//www.microscopyu.com/articles/phasecontrast/
phasemicroscopy.html
Phase contrast microscopy is a contrast-enhancing
optical technique that can be utilized to produce
high-contrast images of transparent specimens,
such as living cells, thin tissue slices,
lithographic patterns, fibers, latex dispersions,
glass fragments, and subcellular particles
(including nuclei and other organelles).
http//www.youtube.com/watch?vI4ZQm-CAgL8
at050-520 http//www.youtube.com/watch?vWvyCg1
uzG5c
43
Crystals Growth by Differential Interference
contrast microscopy (DIC)
Growth spiral on cadmium iodide crystals
growing From water solution (1025x).
http//www.youtube.com/watch?vP2teE17zT4I
at2305-3050 http//micro.magnet.fsu.edu/primer/
techniques/dic/dichome.html
Fluorescence microscopy - medical organic
materials
http//www.youtube.com/watch?viPrZ84kHH2U
at150-315 http//micro.magnet.fsu.edu/primer/t
echniques/fluorescence/fluorhome.html https//www.
youtube.com/watch?vBmRRYPDq4bYww.youtube.com/watc
h?vn2asdncM
44
Scanning Confocal Optical Microscopy
http//micro.magnet.fsu.edu/primer/techniques/conf
ocal/index.html
Confocal microscopy is an optical imaging
technique used to increase optical resolution and
contrast of a micrograph by adding a spatial
pinhole placed at the confocal plane of the lens
to eliminate out-of-focus light. Scanning
confocal optical microscopy (SCOM) is a technique
for obtaining high-resolution optical images with
depth selectivity. (a laser beam is used) The key
feature of confocal microscopy is its ability to
acquire in-focus images from selected depths, a
process known as optical sectioning. Images are
acquired point-by-point and reconstructed with a
computer, allowing three-dimensional
reconstructions of topologically complex objects.
http//www.youtube.com/watch?vmrjgNyKX8-w Why
confocal? to105
http//www.youtube.com/watch?vpuT1ccMWKyQ
at040-136 240-256
http//www.youtube.com/watch?vAxrst4T__YY
scanning
45
Scanning Confocal Optical Microscopy
http//www.olympusconfocal.com/theory/confocalintr
o.html Introduction
Three-Dimensional Optical Microscopy
Critical dimension measurements in semiconductor
metrology
w
Cross-sectional image with line scan at PR/Si
interface of a sample containing 0.6?m-wide lines
and 1.0?m-thick photoresist on silicon. The
bottom width, w, determining the area of the
circuit that is protected from further
processing, can be measured accurately by using
SCOP. Measurement of the patterned photoresist
is important because it allows the process
engineer to simultaneously monitor for defects,
misalignment, or other artifacts that may affect
the manufacturing line.
http//www.youtube.com/watch?voluJW7uK7rwindex1
2listPL200E1A86911B0422 to2.44 coral under
confocal http//micro.magnet.fsu.edu/primer/virtua
l/confocal/index.html interactive tutorial
46
Lecture-3 Optical Microscopy

• Introduction
• Lens formula, Image formation and Magnification
• Resolution and lens defects
• Basic components and their functions
• Common modes of analysis
• Specialized Microscopy Techniques
• Typical examples of applications

47
Typical Examples of OM Applications
48
Grain Size Examination
1200C/30min
Thermal Etching
a
1200C/2h
20?m
b
A grain boundary intersecting a polished surface
is not in equilibrium (a). At elevated
temperatures (b), surface diffusion forms a
grain-boundary groove in order to balance the
surface tension forces.
49
Grain Size Examination
Objective Lens
x100
Reflected OM
50
Grain Growth - Reflected OM
30mm
5mm
Polycrystalline CaF2 illustrating normal
grain growth. Better grain size distribution.
Large grains in polycrystalline spinel (MgAl2O4)
growing by secondary recrystallization from a
fine-grained matrix
51
Liquid Phase Sintering Reflective OM
Amorphous phase
40mm
Microstructure of MgO-2 kaolin body
resulting from reactive-liquid phase sintering.
52
Image of Magnetic Domains
Magnetic domains and walls on a (110)-oriented
garnet crystal (Transmitted LM with oblique
illumination). The domains structure is
illustrated in (b).
53
Phase Identification by Reflected Polarized
Optical Microscopy
YBa2Cu307-x superconductor material (a)
tetragonal phase and (b) orthorhombic phase with
multiple twinning (arrowed) (100 x).
54
Specialized OM Techniques

• Enhancement of Contrast
• Darkfield Microscopy
• Phase contrast microscopy
• Differential interference contrast microscopy
• Fluorescence microscopy-medical organic
  materials
• Scanning confocal optical microscopy (relatively
  new)
• Three-Dimensional Optical Microscopy
• inspect and measure submicrometer features in
  semiconductors and other materials
• Hot- and cold-stage microscopy
• melting, freezing points and eutectics,
  polymorphs, twin and domain dynamics, phase
  transformations
• In situ microscopy
• E-field, stress, etc.
• Special environmental stages-vacuum or gases

http//www.nature.com/nmeth/journal/v12/n6/full/nm
eth.3400.html
55
Hot-stage POM of Phase Transformations in
Pb(Mg1/3Nb2/3)O3-PbTiO3 Crystals
(a) and (b) at 20oC, strongly birefringent
domains with extinction directions along
lt100gtcubic, indicating a tetragonal symmetry (c)
at 240oC, phase transition from the tetragonal
into cubic phase with increasing isotropic areas
at the expense of vanishing strip domains.
?n
T(oC)
56
E-field Induced Phase Transition in
Pb(Zn1/3Nb2/3)O3-PbTiO3 Crystals
c
a
b
Single domain
Schematic diagram for in situ domain
observa- tions.

• Domain structures of PZN-PT
• crystals as a function of E-field
• E20kV/cm, (b) e23.5kV/cm
• (c) E27kV/cm
• Rhombohedral at E0 and
• Tetragonal was induced at Egt20kV/cm

57
Review - Optical Microscopy

• Use visible light as illumination source
• Has a resolution of o.2?m
• Range of samples characterized - almost
  unlimited for solids and liquid crystals
• Usually nondestructive sample preparation may
  involve material removal
• Main use direct visual observation preliminary
  observation for final charac-terization with
  applications in geology, medicine, materials
  research and engineering, industries, and etc.
• Cost - 15,000-390,000 or more

58
Characteristics of Materials Can be determined
By OM
Morphology (shape and size), phase distribution
(amorphous or crystalline), transparency or
opacity, color, refractive indices, dispersion of
refractive indices, crystal system,
birefringence, degree of crystallinity,
polymorphism and etc.
59
Limits of Optical Microscopy

• Small depth of field lt15.5mm
• Rough surface
• Low resolution 0.2mm
• Shape of specimen
• Thin section or polished surface

Cover glass
specimen
Glass slide
resin
20mm

• Lack of compositional and crystallographic
  information

60
Optical Microscopy vs Scanning Electron
Microscopy
25mm
radiolarian
OM
SEM
Small depth of field Low resolution
Large depth of field High resolution
http//www.mse.iastate.edu/microscopy/
Radiolarian marine protozoan
61
Scanning Electron Microscopy (SEM)

• What is SEM?
• Working principles of SEM
• Major components and their functions
• Electron beam - specimen interactions
• Interaction volume and escape volume
• Magnification, resolution, depth of field and
  image contrast
• Energy Dispersive X-ray Spectroscopy (EDS)
• Wavelength Dispersive X-ray Spectroscopy (WDS)
• Orientation Imaging Microscopy (OIM)
• X-ray Fluorescence (XRF)

http//www.mse.iastate.edu/microscopy http//scien
ce.howstuffworks.com/scanning-electron-microscope.
htm/printable