Surface Stress Meters

A surface stress meter measures the internal stress value of a transparent object such as glass and other similar crystals by measuring the optical path difference between two polarized paths of light. This instrument finds huge application in stress level measurement of optical glass products, material science, crystal analysis, and more. Barnett Technical Services offers advanced solutions for accurate and dependable internal stress measurement and analysis. We take pride in being an authorized distributor of Orihara surface stress meters. Orihara is a renowned manufacturer of optical measuring instruments and offer a range of surface stress meter models tailored to suit specific application requirements. These meters enable non-destructive testing (NDT) of transparent and crystalline objects.


Surface stress meter on tempered glass using the optical waveguide effect...

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Handheld version of the FSM-6000X for measurements on larger glass panels...

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Stress distribution in glass through scattered light photoelasticity...

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Combination of FSM-6000X and SPL-2000 in one instrument...

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About Surface Stress Meters

Residual stress level measurement offers an estimate about how much load and stress an optical component can withstand in consumer products, avionics, optical imaging, remote sensing, and many other fields. Orihara’s surface stress meters offer non-destructive, computer-aided analysis with a high level of accuracy. These meters measure the Depth of Layer (DOL) and Compressive Stress (CS) of optical components.

Surface Stress Meter Offerings

Glass Surface Stress Meter Model FSM-6000X : The FSM-6000 X series is specifically designed for surface stress measurement of glass. It enables non-destructive optical measurement of stress and depth levels of glass objects such as chemically tempered glass and physically tempered glass. This system can be configured with illumination wavelengths at 365, 596, or 790 nm; and is available in models that include all three of these wavelengths in a single system. Typical values that may be read include:
  • DOL: 5-200 µm (depending on illumination wavelength)
  • CS: 0-1000 MPa
Glass Surface Stress Meter Model FSM-7000H : The FSM-7000 H series is a handheld version of the FAM-6000X using 596 nm illumination. This system is ideally suited for measurements of large glass panels. Typical values that may be read include:
  • DOL: 10-100 µm
  • CS: 0-1000 MPa
Scattered Light Photoelastic Stress Meter Model SLP-2000 : This device measures stress distribution in chemically tempered glass, strengthened through ion exchange between Li+ and Na+, using scattered light photoelasticity. For some dual-layer systems such as glass strengthened with a mixed liquid of KNO3 and NaNO3, the SLP-2000 may be used in combination with the FSM-6000 – the FSM-6000 measures the K+ layer, while the SLP-2000 measures the Na+ layer. The SLP-2000 may also be used for measuring stress distribution in DIOX and thermally tempered glass. Typical values that may be read include:
  • DOL: 10-400 µm
  • CS: 0-2000 MPa
Scattered and Refractive Polarimeter Model SRP-1000: This system represents a combination of the SLP-2000 and FSM-6000 system by simultaneously measuring the stress distribution in a range of complex glasses such as those hardened through 2-step IOX glass (Li+⇔Na+ and K+⇔Na+) using both the optical waveguide effect and scattered light.

Advantages of Using Surface Stress Meters

Here are some benefits of using surface stress meters for your glass samples
  • Accuracy of stress levels: Measurements are typically active to within 5%.
  • Non-destructive: Their non-destructive method helps in preserving the samples for further analysis and inspection without damaging their properties and structure.
  • Visualization and analysis: Stress meters facilitate easy visualization for engineers to actually see and understand how stress is dispersed throughout the material. This helps understand the weak areas, defects, and stress points before use which would otherwise lead to failures. You can also understand the magnitude of stress. This also enables a comprehensive quantitative and qualitative analysis.
  • Cost effectiveness: Stress meters add to the cost-effectiveness of the object by identifying possible defects and failure probabilities beforehand.
  • Education: They are useful in the education sector for demonstrating stress levels in objects to students.
  • New discoveries and research: They help determine the reaction of various transparent objects with fluids, metals, and chemicals that come in contact with them. This can help devise new formulations, materials, and more.
  • Prevents deformation of objects: Accurate residual stress level measurements are crucial to prevent premature deformation of glass or plastic objects or cracking.

Applications of Polarized Stress Meters

The diverse applications of surface stress meters highlight their versatility and importance in scientific, industrial, and educational settings. They significantly contribute to advancements in the analysis and ensuring the reliability of diverse materials and structures.
  • Material Science: These meters are employed across industries for material testing to ensure quality, purity, and structural integrity.
  • Avionics: Stress meters are used in avionics to assess the stress distribution within various glass components of aircraft where surface hardening is critical to their stability.
  • Automotive: Surface stress meters are used for analyzing stress patterns in glass products such as windshields.
Feel free to contact our team via phone or email for any further information you need regarding our stress meter offerings and how it can help in your application.