Overview
ISO 17861:2014 defines a standardized measurement method for spectral transmittance of fine ceramics (advanced technical ceramics) thin films under humid conditions. The standard targets optical property changes caused by water adsorption in porous or columnar ceramic coatings. It prescribes environmental control, instrumentation, calibration and measurement sequences to compare transmittance in vacuum, low-humidity and high-humidity atmospheres.
Key topics and technical requirements
- Scope: Measurement of spectral transmittance of thin ceramic films deposited on transparent substrates (glass, polymer, etc.) to evaluate humidity-induced optical changes.
- Instrumentation: Recommended a double-beam spectrophotometer (integrating-sphere preferred) with desirable range ~300–2 500 nm; wavelength accuracy typically ±0.2 nm (UV‑visible) and ±1.0 nm (NIR); high repeatability at 0.1–0.5 nm.
- Environmental mini-chamber: Airtight chamber with quartz windows, valves and ports to permit measurements in vacuum, low-humidity and high-humidity without removing the sample. Leak testing and vacuum integrity are required.
- Vacuum and humidity control: Vacuum evacuation to <~40 Pa (pump speed >1.0 l/s recommended); temperature/humidity chamber set at 23 °C ±2 °C with test RH points typically 40 % ±2 % (low) and 80 % ±2 % (high). Heating of the mini-chamber during evacuation (up to 130 °C) is allowed to reduce residual water, but cooling to room temperature is required before measurement.
- Measurement procedure: Defined wavelength interval (e.g., 0.2 nm), scan speeds (different settings for <850 nm and >850 nm), baseline correction and spectrometer calibration (wavelength standards such as didymium/holmium oxide, polystyrene for IR).
- Data evaluation & reporting: Compare spectra across environments, calculate shifts (e.g., half-transmittance wavelength), and report instrument settings, environmental conditions, and sample description.
Applications and users
ISO 17861 is practical for organizations that develop, test or specify optical ceramic coatings where humidity stability matters:
- Manufacturers of anti-reflective coatings, IR/X-ray sensor filters, and optical band-pass filters for medical diagnostics.
- Quality assurance and R&D labs evaluating humidity-induced refractive index or transmittance shifts in porous/columnar thin films.
- Test labs requiring reproducible, comparable transmittance data for product specifications, failure analysis or material selection.
Related standards
- ISO 9211-1 (Optics and photonics - Optical coatings - Definitions)
- ISO 8980-3 (Ophthalmic optics - Transmittance specifications and test methods)
Keywords: ISO 17861, fine ceramics, spectral transmittance, thin films, humidity testing, environmental mini-chamber, spectrophotometer, water adsorption, optical coatings.