ISO 29301:2023

Overview

ISO 29301:2023 - "Microbeam analysis - Analytical electron microscopy - Methods for calibrating image magnification by using reference materials with periodic structures" - specifies a standardized calibration procedure for image magnification in a transmission electron microscope (TEM). The standard applies to images recorded across a wide magnification range and to detectors such as photographic film, imaging plates, and digital image sensors (CCD/CMOS). It covers use of reference materials with periodic structures (diffraction grating replicas, super‑lattices, analysing crystals, crystal lattice images of carbon/gold/silicon) and includes scale bar calibration. ISO 29301:2023 is the third edition (minor revision) and does not apply to dedicated CD‑TEM or STEM instruments.

Key technical topics and requirements

• Scope and definitions: formal definitions for image magnification, image file, HFW (horizontal field width), CRM/RM, alignment and related TEM terms.
• Reference materials: requirements for certified reference materials (CRM) and reference materials (RM) with periodic structures, plus guidance on storage and handling.
• Calibration workflow: structured procedures covering mounting CRM/RM, setting TEM operating conditions, capturing digitized images, and digitizing photographic film or imaging plates.
• Measurement and digitization: procedures for selecting pixel resolution, digitizing reference scales (glass scale), and measuring angle‑corrected distances from digitized images.
• Calibration computations: methods to determine pixel size, calibrate scale units, calculate image magnification, and calibrate displayed scale bars.
• Quality and traceability: requirements for reporting, assessing accuracy, estimating measurement uncertainty, and producing a calibration report.
• Supporting material: annexes include parameters that influence magnification, flowcharts, guidance on averaging lines, reference material lists, and example test reports.

Practical applications and who uses this standard

ISO 29301:2023 is intended for:

• TEM operators and microscopy facilities performing quantitative imaging.
• Calibration and metrology laboratories seeking traceable magnification measurements.
• Research labs in materials science, semiconductors, nanotechnology, metallurgy, and biology that require accurate size measurements from TEM images.
• Quality assurance teams and instrument vendors validating instrument performance.

Benefits include reproducible magnification calibration, improved measurement traceability, consistent scale bar accuracy, and better comparability of TEM-based dimensional data.

Related standards

• ISO Guide 35 - Reference materials: characterization, homogeneity and stability.
• ISO/IEC 17025:2017 - Competence of testing and calibration laboratories.
• ISO 17034 - Competence of reference material producers.

Keywords: ISO 29301:2023, TEM magnification calibration, transmission electron microscope, reference materials, periodic structures, CRM, scale bar calibration, imaging plate, photographic film, image sensor.