ISO 18221:2025

Overview

ISO 18221:2025 - Microscopes - Microscopes with digital imaging displays - Information provided to the user regarding imaging performance defines the minimum information that microscope manufacturers must provide about imaging performance when microscopes include digital displays. This second edition updates terms, formulas and reporting requirements for the digital imaging path (objective → image sensor → digital display). It does not apply to confocal microscopes. For direct visual eyepiece terminology see ISO 8039 and ISO 10934.

Key topics and technical requirements

The standard standardizes terminology and minimum user information for digital microscopy systems. Major technical topics explicitly addressed include:

• Terms and definitions for digital microscopy systems, image sensors and digital displays (digital microscopy system, image sensor, digital display, resolving power limit, pixel pitch).
• Magnification definitions and formulas:
  • Optical magnification (image on sensor).
  • Display lateral magnification (image presented on monitor).
  • Visual display magnification (observer’s perceived magnification), with the reference viewing distance of 250 mm.
• Resolving power limits reported in line pairs per millimetre (lp/mm):
  • Optical resolving power limit (function of NA and wavelength).
  • Sensor resolving power limit (function of sensor pixel pitch, magnification and sensor operation mode/binnings).
  • Display resolving power limit (function of display pixel pitch and display magnification).
  • System resolving power limit - the minimum of optical, sensor and display limits.
• Useful range of magnification and viewing distance, including the perceptual limits (angle subtended by resolved details).
• Object field, pixel size in object space and depth of field, with updated formulae and reporting expectations.
• Manufacturer information to users (Clause 10): general system specs and imaging performance data that must be provided (examples given in Annex A).

Practical applications and who uses this standard

ISO 18221:2025 is practical for stakeholders who design, buy, specify or certify digital microscopes:

• Manufacturers and product managers - to prepare consistent, standards-compliant datasheets and user information about imaging performance.
• Quality engineers and compliance teams - to verify declared resolving power, magnification ranges, pixel size in object space and depth of field.
• Laboratory managers and procurement specialists - to compare microscope models objectively when purchasing digital microscopy systems for research, clinical, industrial inspection or education.
• Metrology labs and integrators - for system validation, performance reporting and avoiding Moiré or undersampling issues.
• Regulatory and standards professionals - to harmonize specifications across suppliers.

Related standards

• ISO 10934 - Microscopes: Vocabulary for light microscopy (referenced for terminology).
• ISO 8039 - Terms for direct visual observation with eyepieces.

Keywords: ISO 18221:2025, microscopes with digital displays, imaging performance, resolving power, magnification, pixel pitch, image sensor, digital display, microscope manufacturer guidance.