Overview
ISO 8255-2:2013 - Microscopes - Cover glasses - Part 2 specifies requirements and test methods for the quality of materials, standards of finish, and mode of packaging for microscope cover glasses used in transmitted light microscopy (400–760 nm). It complements ISO 8255-1 (dimensional tolerances and optical properties) by addressing material quality, surface defects, packaging suitability, sampling and test procedures.
Key topics and requirements
- Scope: Applicable to cover glasses intended for transmitted-light microscopes (400–760 nm).
- Visual inspection conditions: Observations by the unaided eye (vision 1.0) under diffuse “cool white” illumination at ~1 500 ±150 lx; tests valid within six months of packaging.
- Surface quality & inclusions: Freedom from pits, seeds, cords, stones, lines, abrasions, scratches and cracks (AQL 1.5).
- Cleanliness & cloudiness: Free of cloudiness, fingerprints and particulate contamination (AQL 1.5).
- Edge finish: No chipped corners or nicks exceeding 1.0 mm length and 0.5 mm depth (AQL 1.0).
- Non-flatness and non-parallelism:
- Waviness must pass the specified test method.
- Thickness variation within a single glass (≤ 60 mm max length) no more than half the total thickness tolerance from ISO 8255-1; in a sample of 100, accept up to five failures.
- Durability (chemical resistance/solubility): Surface chemical durability and resistance to atmospheric attack must meet solubility test criteria.
- Adhesion: Cover glasses must be free from adhesion defects (AQL 1.5).
- Residual stress / birefringence: For polarized light use, optical path difference ≤ 5 nm measured through the principal plane (inspection level S‑2, AQL 1.0).
- Sampling & acceptance: Lot inspection sampling follows ISO 2859-1; Annex A provides sample sizes and single sampling plans.
- Packaging & marking: Packages must allow contamination-free handling, correct labelling and stated counts/mass.
Practical applications and users
- Manufacturers and suppliers of microscope slides and cover glasses use ISO 8255-2 to set production, inspection and packaging criteria.
- Quality managers and procurement professionals use the standard to specify accepted lots and supplier certification.
- Microscopy labs (research, clinical, industrial) rely on compliant cover glasses to ensure optical performance in transmitted-light and polarized-light imaging.
- Test labs and inspectors apply the described test methods and AQL sampling plans for conformity assessment.
Related standards
- ISO 8255-1:2011 - Dimensional tolerances, thickness and optical properties.
- ISO 2859-1:1999 - Sampling procedures for inspection by attributes (AQL schemes).
- ISO 11455:1995 - Determination of birefringence in raw optical glass.
Keywords: ISO 8255-2, microscope cover glasses, cover glass quality, transmitted light microscopy, birefringence, packaging, surface quality, AQL, sampling, test methods.
Open preview (PDF)Microscopes — Cover glasses — Part 2: Quality of materials, standards of finish and mode of packaging
