Introduction
In the realm of personal vision correction products, optical clarity is one of the key parameters for evaluating their performance. Clarity directly affects the visual experience, and haze and light transmittance are important indicators to quantify this characteristic. As a precision optical measurement equipment, haze transmittance meter can objectively and accurately evaluate the optical properties of materials, providing reliable data support for product development and quality control.
Haze and light transmittance definition
Light transmittance refers to the percentage of transmitted light flux and incident light flux after light passes through the material, reflecting the overall light transmission ability of the material. Haze refers to the percentage of scattered light flux and total transmitted light flux that deviates from the direction of incidence more than a certain angle in the transmitted light, and characterizes the degree of haziness caused by scattering inside or on the surface of the material. The relationship between the two can be expressed by the following formula:
H = (Td / Tt) × 100%
where H is the haze value, Tdis the scattered transmitted light flux, Ttis the total transmitted light flux. Low haze and high light transmission often mean better optical clarity.
Instrumental measurement principle
The haze transmittance meter is designed based on the integrating sphere principle. The parallel beam emitted by the light source illuminates the sample, and the transmitted light enters the integrating sphere. The photodetector built into the instrument measures the total transmitted light flux and the scattered light flux respectively. The light transmittance and haze values are obtained by calculation. The measurement process requires strict control of the angle of incident light, spectral conditions, and environmental factors to ensure that the results meet the requirements of relevant standards.
Measurement standards and methods
A number of domestic and foreign standards stipulate the measurement methods of haze and light transmittance of transparent materials. Common standards include the international standards ASTM D1003 and ISO 14782. These standards set clear requirements for sample preparation, instrument calibration, measurement steps, and data processing. For vision correction products, measurements are usually made in the optical area of the center of the product, and the sample needs to be cleaned and tested under standard temperature and humidity conditions.
| Key measurement parameters | Description |
| Spectral conditions | Usually use C light source or D65 standard light source |
| Measure geometric conditions | The angle of incidence is usually 0 degrees (vertical incidence) |
| Sample requirements | The surface is clean, flat, and free of visible defects |
| Data output | Light transmittance percentage, haze percentage |
Clarity assessment applications
Measured by haze transmittance meter, quantitative data on the optical clarity of vision correction products can be obtained. The light transmittance value reflects the efficiency of light energy passing, and the haze value is directly related to visual haziness. During the product development phase, this data can be used to compare the effects of different materials, processes, and coating treatments. In quality control, the acceptance range of haze and light transmittance can be set to ensure stable product performance from batch to batch.
Analysis of influencing factors
The characteristics of the material itself are the main factors affecting haze and light transmittance. Light scattering can all be caused by the purity of the polymer matrix, the dispersion of additives, internal stresses or microcrystalline structure caused by the molding process, as well as the quality of surface polishing, cleanliness and coating uniformity. Environmental factors such as temperature and humidity changes can also lead to changes in the microstructure of materials, which in turn affects the measurement results. Systematic analysis of these factors can help optimize product optical performance.
| Categories of influencing factors | Typical example |
| Inherent properties of materials | Uniformity of refractive index of matrix resin |
| Processing technology | Molding temperature and pressure control |
| Surface state | Polishing marks, cleanliness, coating uniformity |
| environmental conditions | Ambient temperature and humidity at the time of measurement |
Technology development trends
With the advancement of materials science and the development of measurement technology, haze transmittance measurement is evolving towards higher accuracy, faster speed, and wider range of applications. The new instrument integrates an automated sample stage, multi-angle measurement capabilities, and spectral analysis capabilities to provide more comprehensive optical characterization. The development of data analysis software has also made it possible to more intuitively correlate measurement results with visual perception and assist in product design optimization.
Conclusion
Haze transmittance meters provide an objective and reproducible means of measurement for evaluating the optical clarity of vision correction products. Through standardized measurement methods, combined with systematic analysis of materials, processes, and environmental factors, product development and quality control can be effectively guided, helping to improve product visual performance and user experience.
References
1. The standard method part refers to the ASTM D1003 standard "Standard Test Method for Haze and Light Transmittance of Plastic Transparent Materials".
2. The measurement principle is partly based on the optical engineering literature related to integral sphere photometric measurement technology.
3. Influencing factor analysis A number of technical articles on the study of optical properties of polymer materials are synthesized.