Overview
ISO 10345-1:1992 specifies a standardized tensile test method for determining the stress‑optical coefficient of isotropic glass. The stress‑optical coefficient is the wavelength‑dependent ratio of induced birefringence (optical path difference) to applied uniaxial stress, a material constant used to calculate stress from measured stress birefringence. This part covers specimen geometry, apparatus, test procedure, measurement accuracy and reporting requirements for laboratory evaluation of glass.
Key topics and technical requirements
- Scope: Applies to isotropic glass; complementary Part 2 covers bending tests.
- Definition: Stress‑optical coefficient = ratio of birefringence effect to applied uniaxial stress.
- Specimen dimensions and condition:
- Rectangular cross‑section area ≥ 25 mm² and length ≥ 50 mm.
- Breadth and height not less than 4 mm (≥6 mm if pivot-mounted).
- Surfaces for light transmission ground and polished; avoid inhomogeneous residual stresses.
- Apparatus:
- Height measuring device accurate to 0.01 mm.
- Stressing equipment with force measuring device accurate to 1% and alignment to avoid bending/shear.
- Polarization measuring equipment with compensator capable of measuring optical path difference to 5 nm.
- Light source: white light with interference filter for 589.3 nm (or state alternative wavelength).
- Procedure and measurement:
- Tests at room temperature (15 °C to 35 °C); deviations must be reported.
- Measure optical path difference at the specimen centre for at least two tensile forces (recommended >100 N and differing by >200 N).
- Keep optical measurement position within specified vertical (≤10 mm) and horizontal (≤¼ specimen height) limits.
- Determine K from measured optical path differences; when more than two forces are used, determine K by graph or calculation.
- Reporting: Include reference to ISO 10345‑1, glass type, wavelength, testing temperature (if outside range), and the stress‑optical coefficient with units and chosen testing forces.
Applications and users
ISO 10345‑1 is used where accurate optical stress analysis or stress measurement from birefringence is required:
- Optical glass manufacturers and quality control laboratories
- Materials scientists and research labs studying stress–optical behavior
- Metrology and calibration labs performing stress birefringence measurements
- Design and failure‑analysis teams in optics and glass components
Practical applications include stress mapping in lenses and glassware, calibration of photoelastic measurements, and verifying material constants for optical simulation.
Related standards
- ISO 10345‑2 - Glass - Determination of stress‑optical coefficient: Part 2: Bending test
- ISO 9802 - Raw optical glass: vocabulary (referenced for terminology)
Keywords: ISO 10345‑1:1992, stress‑optical coefficient, tensile test, glass, birefringence, polarization measurement, optical path difference.
