Goggles optical performance testing service

Goggles Optical Performance Testing Service – Accredited ISO/IEC 17025 Visual Quality and Safety Assessment for the Croatian Market

Optical performance is a critical quality parameter for goggles, safety spectacles, face shields, and visors used in healthcare, industrial, chemical, welding, sports, and rescue applications. The ability of eye‑protection devices to provide clear, undistorted, and comfortable vision is essential for user safety, task accuracy, and fatigue reduction during prolonged use. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Državni inspektorat, the Ministarstvo gospodarstva i održivog razvoja, and the Carinska uprava enforce strict quality and safety standards aligned with EU regulations (including the Personal Protective Equipment Regulation (EU) 2016/425) and HRN EN (Croatian standards based on European norms), the accurate evaluation of optical performance is essential for product certification, CE marking, supplier qualification, type testing, quality control in manufacturing, and import‑export processes. Our laboratory offers a comprehensive goggles optical performance testing service, applying standardized methods such as EN 166, EN 167, EN 168, ISO 12609, ANSI Z87.1, HRN EN 166, and HRN EN 167 to measure spherical power, cylindrical power, prismatic deviation, light transmission, haze, clarity, and resistance to optical degradation under controlled environmental conditions. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Croatian authorities and notified bodies, making them indispensable for regulatory compliance, product validation, and market access in Croatia and the European Union.

Goggle and Visor Samples We Regularly Test

Our laboratory receives a wide variety of goggles, spectacles, and visors for optical performance testing. Typical samples include:

• Safety goggles and spectacles – for industrial, laboratory, and medical use with clear, tinted, and prescription lenses.
• Face shields and welding visors – with integrated protective lenses and filters.
• Full‑face respirators and PAPR visors – for chemical and biological protection.
• Sports and recreational goggles – for skiing, cycling, and motorsports.
• Prescription safety eyewear – with corrective lenses and optical inserts.
• Prototype and new lens designs – submitted by manufacturers for validation of optical performance before series production.
• Field‑retrieved goggles – for failure analysis and remaining life assessment.

Spherical and Cylindrical Power Measurement – Evaluating Refractive Accuracy

Spherical power (the focusing power of the lens) and cylindrical power (the astigmatic correction) are fundamental optical parameters that determine the clarity and the focusing accuracy of the lens. Our tests measure these parameters using a focimeter (lensometer) or an automatic lensmeter, following international standards and the requirements of the Croatian PPE and medical device sectors.

• Spherical power measurement (EN 167 / ISO 12609 / HRN EN 167 / NTC 5600 – for the refractive power) – we mount the goggle lens (or the finished goggle) in a focimeter (lensometer) and measure the spherical power (in diopters, D) at the optical center of the lens. The measurement is performed at a specified wavelength (e.g., 546 nm). The spherical power is reported. We report the spherical power (in D) and the deviation from the nominal value.
• Cylindrical power and axis measurement (EN 167 – variant / NTC 5601 – for the astigmatic correction) – we measure the cylindrical power (in D) and the axis angle (in degrees) of the lens, using the focimeter or an automatic lensmeter. The cylindrical power corrects the astigmatism. We report the cylindrical power (in D), the axis angle (in °), and the deviation from the nominal value.
• Prismatic power and deviation measurement (EN 167 / NTC 5602 – for the image displacement) – we measure the prismatic power (in prism diopters, Δ) and the prismatic deviation (the displacement of the image) of the lens, using a focimeter or a prism measuring instrument. A high prismatic deviation can cause double vision and eye strain. We report the prismatic power (in Δ) and the prismatic deviation.
• Measurement of the optical center location (NTC 5603 – for the centration accuracy) – we measure the location of the optical center of the lens relative to the geometric center of the goggle frame. A misalignment can cause visual discomfort. We report the optical center location (in mm) and the deviation.
• Spherical and cylindrical power measurement at different temperatures (NTC 5604 – for the thermal effect) – we condition the lens at a specified temperature (e.g., 40 °C, 60 °C) and then measure the spherical and cylindrical powers. The effect of temperature on the refractive power is evaluated. We report the power at each temperature.

Light Transmission and Spectral Transmittance – Evaluating the Luminous Efficiency

The light transmission of the goggle lens determines its brightness and its suitability for different lighting conditions. Our tests measure the total light transmission (in %) and the spectral transmittance (the transmission as a function of the wavelength) using a spectrophotometer. These tests are essential for ensuring the correct light level for the application, especially for tinted lenses, welding filters, and photochromic lenses.

• Total light transmission measurement (EN 167 / ISO 12609 / HRN EN 167 / NTC 5610 – for the luminous transmittance) – we use a spectrophotometer (or a photometer with an integrating sphere) to measure the total light transmission (in %) of the lens over the visible spectrum (380‑780 nm). The measurement is performed with a specified light source (e.g., CIE illuminant D65). We report the total light transmission (in %) and the transmission class (e.g., clear, tinted, or dark).
• Spectral transmittance measurement (NTC 5611 – for the wavelength‑specific transmission) – we measure the spectral transmittance (the transmittance vs. wavelength) of the lens using a spectrophotometer, over a wavelength range of 280‑780 nm (for UV and visible light). The spectral transmittance curve is reported. We report the spectral transmittance curve and the UV cut‑off wavelength.
• UV and blue‑light blocking measurement (NTC 5612 – for the protection against harmful radiation) – we measure the transmittance in the UV‑A (315‑380 nm), UV‑B (280‑315 nm), and blue‑light (400‑450 nm) ranges. The blocking efficiency (in %) is calculated. We report the UV‑A, UV‑B, and blue‑light blocking efficiencies (in %).
• Light transmission at different angles of incidence (NTC 5613 – for the angular dependence) – we measure the light transmission at different angles of incidence (e.g., 0°, 15°, 30°) to evaluate the effect of the viewing angle on the brightness and the color shift. We report the transmission at each angle.
• Light transmission after aging (NTC 5614 – for the durability assessment) – we age the lens (e.g., by UV exposure, thermal aging, or abrasion) and then re‑measure the light transmission. The change in the transmission and the yellowing (the increase in the yellow index) are reported. We report the transmission after aging and the yellowing.

Optical Distortion and Clarity – Evaluating the Image Quality

Optical distortion (the deviation of the light rays from the ideal path) and the clarity (the sharpness of the image) are critical for ensuring that the goggles do not degrade the visual performance. Our tests measure the distortion and the clarity using specialized instruments, following the requirements of EN 167 and EN 168.

• Optical distortion measurement (EN 167 / HRN EN 167 / NTC 5620 – for the image deformation) – we place a test target (e.g., a grid or a resolution chart) behind the lens and observe the distortion of the image through the lens. The distortion is measured using a digital image analysis system or a vision testing device. We report the distortion (in %) and the pass/fail status.
• Haze and clarity measurement (ASTM D1003 / NTC 5621 – for the optical quality of transparent materials) – we measure the haze (in %) and the clarity (in %) of the lens using a haze meter (or a spectrophotometer with an integrating sphere). The haze is the percentage of transmitted light that is scattered by more than 2.5°, and the clarity is the sharpness of the transmitted image. We report the haze and the clarity.
• Resolution and visual acuity measurement (NTC 5622 – for the sharpness of the image) – we use a visual acuity test chart (or a resolution test target) and a calibrated observer to measure the resolution (in line pairs/mm) and the visual acuity (in Snellen or decimal) through the lens. The resolution and the visual acuity are reported. We report the resolution and the visual acuity.
• Contrast sensitivity measurement (NTC 5623 – for the contrast perception) – we measure the contrast sensitivity (the ability to distinguish between different levels of brightness) through the lens, using a contrast sensitivity chart. The contrast sensitivity is reported as a function of the spatial frequency. We report the contrast sensitivity curve.
• Optical distortion at different temperatures (NTC 5624 – for the thermal effect) – we condition the lens at a specified temperature (e.g., 40 °C, 60 °C) and then measure the optical distortion and the clarity. The effect of temperature on the image quality is evaluated. We report the distortion and the clarity at each temperature.

Luminous Efficacy and Color Perception – Evaluating the Visual Performance

The luminous efficacy (the efficiency of the lens in transmitting light) and the color perception (the color rendering and the color shift) are important for tasks that require accurate color discrimination, such as in medical, electrical, and manufacturing applications. Our tests measure these parameters using a spectrophotometer and colorimetric analysis.

• Luminous efficacy measurement (NTC 5630 – for the luminous efficiency) – we calculate the luminous efficacy (in lm/W) from the measured light transmission and the spectral power distribution of the light source. The luminous efficacy is a measure of the efficiency of the lens in transmitting visible light. We report the luminous efficacy (in lm/W) and the luminous efficiency (in %).
• Color rendering index (CRI) measurement (NTC 5631 – for the color reproduction) – we measure the color rendering index (CRI) of the lens, which quantifies the ability of the lens to render the colors of objects accurately. The CRI is calculated from the spectral transmittance data. We report the CRI (Ra) and the individual color rendering indices (R1‑R14).
• Color shift and chromaticity measurement (NTC 5632 – for the color change) – we measure the chromaticity coordinates (x, y) and the correlated color temperature (CCT) of the transmitted light. The shift in the chromaticity (the color shift) is calculated. We report the chromaticity coordinates, the CCT, and the color shift (Δx, Δy).
• Color perception test with standard observers (NTC 5633 – for the human visual assessment) – we use a panel of trained observers to evaluate the color perception through the lens, using a standard color vision test (e.g., the Farnsworth‑Munsell 100‑hue test). The performance of the observers with and without the lens is compared. We report the color perception rating and the pass/fail status.
• Luminous efficacy and color perception after aging (NTC 5634 – for the durability assessment) – we age the lens (e.g., by UV exposure or thermal aging) and then re‑measure the luminous efficacy, the CRI, and the color shift. The change in the color performance and the yellowing are reported. We report the luminous efficacy and the color performance after aging.

Resistance to Abrasion and Surface Degradation – Evaluating the Long‑Term Optical Quality

The optical performance of goggles can degrade over time due to surface abrasion, scratching, and chemical attack. Our tests evaluate the resistance of the lens surface to abrasion and the maintenance of the optical quality after wear, which is essential for ensuring the long‑term visual clarity and the safety of the product.

• Abrasion resistance test (EN 168 / HRN EN 168 / NTC 5640 – for the surface durability) – we subject the lens surface to a specified number of abrasion cycles (e.g., 100 cycles, 500 cycles) using a standard abrasion tester (e.g., a Taber abraser with a specified abrasive wheel or a steel wool pad). After the abrasion, we measure the haze (in %) and the light transmission (in %). The change in the haze and the transmission is calculated. We report the haze after abrasion, the transmission after abrasion, and the increase in the haze (ΔH).
• Scratch resistance test (NTC 5641 – for the resistance to surface scratches) – we apply a specified load (e.g., 5 N, 10 N) to a diamond stylus (or a steel pin) and draw it across the lens surface. The width and the depth of the scratch are measured. The scratch resistance is reported. We report the scratch width, the scratch depth, and the scratch resistance rating.
• Chemical resistance test (ASTM D543 / NTC 5642 – for the resistance to chemicals and cleaning agents) – we apply a specified chemical (e.g., isopropyl alcohol, a cleaning agent, or a solvent) to the lens surface for a specified duration (e.g., 24 hours) and then measure the haze and the light transmission. The change in the optical quality is reported. We report the haze and the transmission after the chemical exposure.
• Resistance to fogging and condensation (NTC 5643 – for the anti‑fog performance) – we expose the lens to a high‑humidity environment (e.g., 40 °C, 95 % RH) for a specified duration (e.g., 30 minutes) and then observe the formation of fog (condensation) on the surface. The fogging resistance is rated. We report the fogging resistance rating and the pass/fail status.
• Resistance to UV‑induced yellowing (NTC 5644 – for the UV stability) – we expose the lens to UV radiation (UVA‑340) for a specified duration (e.g., 200 hours) and then measure the yellow index (YI) and the light transmission. The change in the yellow index is reported. We report the yellow index after UV exposure and the yellowing (ΔYI).

Environmental and Aging Effects – Evaluating the Long‑Term Optical Stability

The optical performance of goggles can change over time due to UV exposure, thermal aging, humidity, and chemical attack. Our environmental and aging tests evaluate the long‑term stability of the optical properties, ensuring the reliability of the product over its service life in the diverse Croatian climate (coastal, continental, and mountainous).

• UV aging and its effect on optical performance (ASTM G154 / NTC 5650 – for the UV‑exposed lenses) – we expose the lens to UV radiation (UVA‑340) and condensation cycles for a specified duration (e.g., 500 hours) and then re‑measure the light transmission, the haze, the yellow index, and the optical distortion. The change in the optical performance is reported. We report the optical properties after UV exposure and the change.
• Thermal aging and its effect on optical performance (ASTM D573 / ISO 188 / NTC 5651 – for the heat‑aged lenses) – we age the lens in an oven at a specified temperature (e.g., 70 °C) for a specified duration (e.g., 7, 14, or 28 days) and then re‑measure the optical properties. The change in the optical performance is reported. We report the optical properties after thermal aging and the retention of the optical quality.
• Humidity and moisture effect (ASTM D570 / NTC 5652 – for the moisture‑exposed lenses) – we condition the lens at a high‑humidity environment (e.g., 40 °C, 95 % RH) for a specified duration (e.g., 7 days) and then re‑measure the optical properties. The effect of the moisture on the optical quality is reported. We report the optical properties after humidity exposure and the moisture uptake.
• Chemical exposure effect (ASTM D543 / NTC 5653 – for the chemically exposed lenses) – we immerse the lens in various chemicals (e.g., mineral oil, cleaning agents, or solvents) for a specified duration (e.g., 7 days) and then re‑measure the optical properties. The change in the optical performance is reported. We report the optical properties after chemical exposure and the compatibility.
• Thermal cycling effect (NTC 5654 – for the thermal fatigue) – we subject the lens to repeated thermal cycles (e.g., from -10 °C to +50 °C) for a specified number of cycles (e.g., 50 cycles) and then re‑measure the optical properties. The change in the optical performance is reported. We report the optical properties after thermal cycling and the effect.

Complementary Tests – Material Identification, Thickness, and Hardness for Optical Correlation

To fully understand the optical performance and to correlate it with the material's properties, we perform complementary tests, including material identification, thickness measurement, and hardness testing.

• Material identification (FTIR, DSC – NTC 5660 – for the polymer identification) – we use Fourier‑transform infrared spectroscopy (FTIR) to identify the chemical composition of the lens material (e.g., polycarbonate, acrylic, or glass) and differential scanning calorimetry (DSC) to measure the glass transition temperature (Tg). The material type and the Tg are correlated with the optical properties and the resistance to aging. We report the material identification and the Tg.
• Thickness measurement (NTC 5661 – for the lens thickness) – we measure the thickness (in mm) of the lens. The thickness is correlated with the light transmission, the haze, and the mechanical strength. We report the thickness and the correlation.
• Hardness testing (ASTM D2240 / NTC 5662 – Shore D or Rockwell for polymers) – we measure the Shore D or the Rockwell hardness of the lens material. The hardness is correlated with the scratch resistance and the wear resistance. We report the hardness and the correlation.
• Density measurement (ASTM D792 / NTC 5663 – for the material density) – we measure the density (in g/cm³) of the lens material. The density is correlated with the optical quality and the impact resistance. We report the density and the correlation.
• Thermogravimetric analysis (TGA) – ASTM E1131 / NTC 5664 – for the thermal stability) – we use TGA to measure the thermal stability and the decomposition temperature of the lens material. The decomposition temperature is correlated with the resistance to thermal aging. We report the decomposition temperature and the mass loss.

Test Report and Recognition in the Croatian PPE, Medical, and Industrial Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (focimeters, spectrophotometers, haze meters, and environmental chambers) and traceability to international standards (NIST, PTB). Our test reports are issued in English (with a Croatian summary available on request) and include:

• Full identification of the goggle or lens sample (manufacturer, model, material, and intended application).
• Detailed description of the test methods applied (EN/ISO/ASTM/ANSI/HRN EN/NTC standards, test conditions, and measurement parameters).
• Numerical results: spherical power (D), cylindrical power (D), prismatic power (Δ), light transmission (%), spectral transmittance curve, haze (%), clarity (%), distortion (%), luminous efficacy (lm/W), CRI, UV‑blocking (%), and property retention after aging (%).
• Graphical data: spectral transmittance curves, distortion maps, and color shift diagrams.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (EN 166, EN 167, EN 168, ANSI Z87.1, HRN EN 166, and the requirements of the HZN, Državni inspektorat, and the PPE Regulation (EU) 2016/425).
• Statement of compliance and pass/fail status.
• Photographs of the test setup, the optical distortion images, and the surface condition of the lens.
• Recommendations for material selection, lens design, and quality control measures to achieve the required optical performance and safety.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98‑3 Guide.

These reports are fully accepted by the Hrvatski zavod za norme (HZN) for the verification of product conformity, by the Ministarstvo gospodarstva i održivog razvoja for industrial safety compliance, by the Državni inspektorat for market surveillance, and by the Carinska uprava (Croatian Customs) for tariff classification and quality verification in the import of goggles and optical PPE. Additionally, we offer consulting services for the selection of optical materials, the design of high‑clarity lenses, and the implementation of quality control programs for optical performance, contributing to the visual safety, comfort, and performance of workers and users in the diverse and growing Croatian market, from the healthcare and industrial sectors to the sports and construction industries.