Learn / TEM & STEM
TEM & STEM
See structure,
defects, and
diffraction clearly.
Learn how electrons form images and diffraction patterns, how to interpret contrast and FFTs, and how to connect microscopy observations back to structure and physics.
1 · Start here
Build the foundation
StoryWhat the Electron SawA scrolling illustrated story about transmission electron microscopy: two electrons leave the same tip, ride the same lenses, split at the specimen into signal and background, and build a diffraction pattern one vote at a time.GuideSAED Indexing, g-Vectors & Real vs. Fake SpotsInteractive guide to indexing SAED patterns by hand: measure g-vectors from spot ratio and angle, see whether those two numbers name one zone axis or several at your measurement precision, and score a twin, double diffraction and a second phase against the same extra spots.GuideThe Three Contrasts of TEMInteractive guide to the three contrast mechanisms of TEM: mass-thickness contrast, diffraction contrast with a live bright-field/dark-field polycrystal tilt simulator, and phase contrast with a CTF defocus lattice-fringe demo.GuideHow to Measure a d-Spacinga spot distance + a calibration → d-spacing with an error barThe four steps from a recorded pattern or image to a d-spacing you can defend: calibrate the camera constant or the pixel size, convert with d = K/R or d = 1/g, carry the uncertainty through, and check how many allowed reflections your error bar covers before calling it an identification.
2 · Learn the core
Master the key concepts
Diffraction & Indexing
Getting to the Condition
Imaging & Contrast
Spectroscopy: EELS & EDS
3 · Use a tool
Work with your data
ToolSAED Zone-Axis Indexerpattern → zone-axis candidatesFree online SAED indexing tool: upload a TEM selected-area electron diffraction pattern, click the transmitted beam and two spots, and identify the zone axis: calibration-free, for FCC, BCC, SC, diamond, HCP and custom lattices.ToolDiffraction Distortion & Camera Constant Calibratorring pattern → distortion + camera constantFree in-browser tool: upload a polycrystalline ring pattern and measure the elliptical distortion of your TEM projector system, its axis, the pattern centre and the camera constant. Feeds the SAED indexer directly.ToolRing Pattern Calibrationring pattern + standard → camera constantCalibrate a TEM diffraction camera in the browser from a gold, aluminium, silicon or other polycrystalline ring pattern: refine the pattern centre, take the radial profile, find the rings, assign them to the standard and fit the camera constant, read the camera length, measure the elliptical distortion, and calibrate the image-diffraction rotation.ToolCBED Symmetry Tableswhole-pattern and bright-field symmetry → point group candidatesBuxton diffraction-group tables in the browser: pick a point group and a zone axis to read the whole-pattern, bright-field and dark-field symmetries a CBED pattern must show, or enter the symmetries you observed and list every point group and zone-axis class consistent with them. All 31 diffraction groups derived from the 32 point groups, not typed in.ToolHRTEM Lattice ToolHRTEM image or FFT → lattice spacings and anglesMeasure lattice spacings from a high-resolution TEM image in the browser: load the image, calibrate the scale, take the FFT of a region, pick the spots to read d-spacings and interplanar angles with sub-pixel refinement, Bragg-filter the image with the chosen reflections, and compute moire fringe spacings for overlapping lattices.ToolEELS Thickness Calculatorlow-loss spectrum → t/λFree in-browser EELS thickness calculator: load a low-loss spectrum (CSV or EMSA/MSA, or a built-in demo), set the zero-loss window, and get t/λ plus absolute thickness in nm from the Malis and Iakoubovskii mean-free-path models, with honest uncertainty notes.
4 · Solve a problem
Troubleshoot real data
5 · Go deeper
Research-level topics
ToolSAED Pattern Simulatorstructure + zone axis → kinematic, Bloch or multislice patternFree in-browser electron diffraction simulator: 604 built-in structures or your CIF, any zone axis, kinematical or many-beam dynamical intensities with a thickness slider, precession, CBED discs, Kikuchi lines, the Ewald-sphere section, your own pattern with a residual fit and off-zone estimate, symmetry readout, CTF and partially coherent HRTEM tableau, HOLZ lines, Bloch-wave STEM images with thermal diffuse scattering (BF, ABF, ADF, HAADF), and a WebGPU frozen-phonon multislice engine (PRISM S-matrix or scanned probe) for supercells with dislocations, stacking faults and column substitutions.GuideWhen Forbidden Reflections AppearInteractive guide to forbidden reflections and superlattices in TEM: why spots are systematically absent, the mechanisms that make them appear (double diffraction, relrods, stacking faults), and a field guide to superlattices in metals and alloys: chemical ordering, the omega phase, long-period structures and their look-alikes.ToolWeak-Beam Tilt Simulatortilts → two-beam and g(3g) conditionsFree in-browser weak-beam dark field trainer: drive a double-tilt holder with alpha and beta over a live Kikuchi map, align any zone axis, walk off along a band, set two-beam, tilt the beam for centred dark field and land on g(3g), while a dislocation image narrows as you go.GuideGrain Orientations & Reciprocal SpaceInteractive TEM guide to grain orientations in reciprocal space: zone-axis tilts with Laue circle and Kikuchi lines, misorientation (LAGB, HAGB, twins), polycrystalline rings and texture arcs, and orientation terminology.
6 · All resources
Every TEM page
- StoryWhat the Electron SawA scrolling illustrated story about transmission electron microscopy: two electrons leave the same tip, ride the same lenses, split at the specimen into signal and background, and build a diffraction pattern one vote at a time.
- ToolSAED Zone-Axis IndexerFree online SAED indexing tool: upload a TEM selected-area electron diffraction pattern, click the transmitted beam and two spots, and identify the zone axis: calibration-free, for FCC, BCC, SC, diamond, HCP and custom lattices.
- ToolSAED Pattern SimulatorFree in-browser electron diffraction simulator: 604 built-in structures or your CIF, any zone axis, kinematical or many-beam dynamical intensities with a thickness slider, precession, CBED discs, Kikuchi lines, the Ewald-sphere section, your own pattern with a residual fit and off-zone estimate, symmetry readout, CTF and partially coherent HRTEM tableau, HOLZ lines, Bloch-wave STEM images with thermal diffuse scattering (BF, ABF, ADF, HAADF), and a WebGPU frozen-phonon multislice engine (PRISM S-matrix or scanned probe) for supercells with dislocations, stacking faults and column substitutions.
- ToolDiffraction Distortion & Camera Constant CalibratorFree in-browser tool: upload a polycrystalline ring pattern and measure the elliptical distortion of your TEM projector system, its axis, the pattern centre and the camera constant. Feeds the SAED indexer directly.
- ToolRing Pattern CalibrationCalibrate a TEM diffraction camera in the browser from a gold, aluminium, silicon or other polycrystalline ring pattern: refine the pattern centre, take the radial profile, find the rings, assign them to the standard and fit the camera constant, read the camera length, measure the elliptical distortion, and calibrate the image-diffraction rotation.
- GuideHow to Measure a d-SpacingThe four steps from a recorded pattern or image to a d-spacing you can defend: calibrate the camera constant or the pixel size, convert with d = K/R or d = 1/g, carry the uncertainty through, and check how many allowed reflections your error bar covers before calling it an identification.
- GuideSAED Indexing, g-Vectors & Real vs. Fake SpotsInteractive guide to indexing SAED patterns by hand: measure g-vectors from spot ratio and angle, see whether those two numbers name one zone axis or several at your measurement precision, and score a twin, double diffraction and a second phase against the same extra spots.
- ToolCBED Thickness ToolFree in-browser tool: upload a two-beam CBED pattern (JPG, PNG, TIFF, Velox EMD), mark the 000 and hkl discs, auto-detect Kossel–Möllenstedt fringe minima, and get thickness with uncertainty plus extinction distance from a Kelly–Allen fit.
- ToolCBED Symmetry TablesBuxton diffraction-group tables in the browser: pick a point group and a zone axis to read the whole-pattern, bright-field and dark-field symmetries a CBED pattern must show, or enter the symmetries you observed and list every point group and zone-axis class consistent with them. All 31 diffraction groups derived from the 32 point groups, not typed in.
- GuideCBED & Lamella ThicknessInteractive schematic: CBED vs SAED, and how two-beam Kossel–Möllenstedt fringes give TEM lamella thickness via the Kelly–Allen extrapolation.
- GuideReciprocal Space & the Ewald SphereInteractive guide to reciprocal space and the Ewald sphere: real vs reciprocal lattice side by side, a live diffraction simulator with voltage, tilt and thickness sliders, and why relrods and excitation error decide which spots light up.
- GuideWhen Forbidden Reflections AppearInteractive guide to forbidden reflections and superlattices in TEM: why spots are systematically absent, the mechanisms that make them appear (double diffraction, relrods, stacking faults), and a field guide to superlattices in metals and alloys: chemical ordering, the omega phase, long-period structures and their look-alikes.
- ToolKikuchi Map NavigatorFree in-browser Kikuchi map for any crystal: see which zone axes sit on which Kikuchi bands, which band to follow to reach a zone axis, how far to tilt, and the double-tilt holder settings that get you there. fcc, bcc, hcp, diamond and ordered alloys built in, or load a CIF.
- ToolWeak-Beam Tilt SimulatorFree in-browser weak-beam dark field trainer: drive a double-tilt holder with alpha and beta over a live Kikuchi map, align any zone axis, walk off along a band, set two-beam, tilt the beam for centred dark field and land on g(3g), while a dislocation image narrows as you go.
- GuideBack Focal Plane & Diffraction FocusInteractive ray diagram of the TEM back focal plane and how the diffraction-focus (intermediate lens) is adjusted for sharp SAED patterns.
- GuideGrain Orientations & Reciprocal SpaceInteractive TEM guide to grain orientations in reciprocal space: zone-axis tilts with Laue circle and Kikuchi lines, misorientation (LAGB, HAGB, twins), polycrystalline rings and texture arcs, and orientation terminology.
- GuideThe Three Contrasts of TEMInteractive guide to the three contrast mechanisms of TEM: mass-thickness contrast, diffraction contrast with a live bright-field/dark-field polycrystal tilt simulator, and phase contrast with a CTF defocus lattice-fringe demo.
- GuideSTEM Detectors: BF, ABF, ADF & HAADFInteractive guide to STEM detector geometry: camera length and atomic number sliders map scattering angles onto the BF, ABF, ADF and HAADF detector rings, a four-detector perovskite image simulator, and a calculator that derives the Z-contrast exponent from the screened Rutherford cross-section instead of assuming it.
- ToolQuantitative HAADFPut an experimental HAADF-STEM image on an absolute scale in the browser: normalise to the detector dark level and probe current, find and refine the atomic columns, integrate each column over a disc or its Voronoi cell, read the statistics, and compare with the fraction-versus-thickness curves exported by the SAED simulator to estimate thickness and the Z-contrast exponent.
- GuideScattering in the TEMInteractive guide to scattering in the TEM: the elastic and inelastic fates of the beam, a real-space vs reciprocal-space simulator on the same specimen, an artifact clinic, and a signal-versus-artifact verdict table for any 80–300 kV (S)TEM.
- GuideWeak-Beam Dark FieldInteractive guide to weak-beam dark field: why strong-beam dislocation images are fat (Pendellösung and extinction distance), the g–3g tilt walkthrough on the Ewald sphere, a Howie–Whelan dislocation-image simulator, the g·b invisibility criterion, and measuring stacking-fault energy from partial separation in Cu.
- ToolBend ContoursBend contours simulated in the browser: pick one of 604 crystals or a CIF, a zone axis and how the foil is bent, and see the many-beam Bloch-wave rocking surface painted on the bent foil as bright-field and dark-field images with the contour pairs, higher orders, fringes and bend centre; move the holder tilt and watch the contours slide, read the radius of curvature from the spacing, and get the eleven most asked questions about bend contours answered.
- ToolTwo-Beam Defect SimulatorSimulate bright-field, dark-field and weak-beam images of dislocations, dislocation dipoles and loops, and stacking faults in the two-beam Howie-Whelan approximation with anomalous absorption, for any of 604 crystals with extinction distances from the structure factors. Inside-outside contrast, alpha fringes and g.b invisibility, computed column by column in the browser.
- Toolg·b Invisibility PlannerPlan a Burgers-vector determination in the TEM: pick a crystal from 604 structures, a zone axis and a line direction, and the page lists every candidate Burgers vector with g.b and g.(b x u) for each reflection of the zone, marks the invisible and residual-contrast conditions, and finds the smallest set of reflections that separates all candidates.
- GuideHRTEM & FFTsInteractive guide to HRTEM and FFTs: a defocus/CTF lattice-image simulator with a true atom-column overlay, the Scherzer-defocus CTF explorer, measuring d-spacings from an FFT with a draggable ROI, how Fourier filtering can conjure fake lattices from noise, and FFT versus SAED.
- ToolHRTEM Lattice ToolMeasure lattice spacings from a high-resolution TEM image in the browser: load the image, calibrate the scale, take the FFT of a region, pick the spots to read d-spacings and interplanar angles with sub-pixel refinement, Bragg-filter the image with the chosen reflections, and compute moire fringe spacings for overlapping lattices.
- GuideReading the EELS SpectrumInteractive guide to electron energy-loss spectroscopy: what the zero-loss peak, plasmons, and core-loss edges each say, why the spectrum only makes sense on a log scale, an element edge-energy lookup with overlap warnings, and when EELS beats EDS (and when it doesn't).
- ToolEELS Thickness CalculatorFree in-browser EELS thickness calculator: load a low-loss spectrum (CSV or EMSA/MSA, or a built-in demo), set the zero-loss window, and get t/λ plus absolute thickness in nm from the Malis and Iakoubovskii mean-free-path models, with honest uncertainty notes.
- ToolEELS Core-Loss QuantificationQuantify a core-loss EELS spectrum in the browser: fit a power-law background before the edge, integrate the edge over a window, compute the hydrogenic K-shell partial cross-section for the collection angle and window, remove plural scattering by Fourier-ratio deconvolution or by convolving the cross-section with the low-loss spectrum, and read the areal density and elemental ratios.
- ToolEDS QuantificationThin-film EDS quantification in the browser: theoretical Cliff-Lorimer k-factors from ionisation cross-sections, fluorescence yields and detector efficiency, the absorption correction as the foil thickens, zeta-factor quantification with thickness, peak-overlap synthesis and least-squares fitting with variance inflation, and beam broadening versus foil thickness for map resolution.
- FAQTEM Troubleshooting FAQTroubleshooting FAQ for transmission electron microscopy: diffraction focus, CBED thickness, the Ewald sphere, TEM contrast, STEM detectors, weak-beam dark field, HRTEM/FFT artifacts, and SAED indexing, each answer linked to its interactive guide.
Other fields: EBSD & TKD · Atom Probe · Crystallography · Phase Transformations · Tribology · Nanoindentation · Scratch Testing · In-situ / FIB.