What is haze?

Haze is an important parameter to measure the optical transparency of transparent or translucent materials. It indicates the percentage of scattered light flux that deviates from the direction of the incident light by more than 2.5° in the light passing through the material. A hazy appearance appears in an object when irregularities in the material or surface conditions cause light scattering. If light is scattered when it shines on or passes through a material, haze appears and the transparency of the product is reduced. The greater the haze, the lower the transparency and clarity of the material, giving it a cloudy or turbid appearance.

The calculation formula of haze is:

Relationship between transparency and haze

Transparency refers to the clarity of a material when light passes through it, that is, the ability to clearly observe an object through the material. Materials with high transparency can make objects look clearer and have sharper edges. Transparency focuses on the visual effect of observing an object through a material, while haze is a physical indicator that quantifies the degree of light scattering. Even if a material has high transmittance, if the haze is high, the transparency will still be poor. In practical applications, such as mobile phone screens and eyeglass lenses, materials with high transparency and low haze are required to ensure clarity of observation.

In summary, transparency and haze are independent in the evaluation of optical properties, but they influence each other and are important indicators for measuring the visual clarity of materials.

Relationship between light transmittance and haze

Transmission refers to the ratio of the luminous flux passing through the material to the incident luminous flux , reflecting the strength of the material's light transmission ability . Haze reflects the proportion of scattered light in the light passing through the material , affecting the clarity of the material. The two are independent indicators. A material with high transmittance does not necessarily have low haze, and vice versa. A material can have both high transmittance and high haze (such as frosted glass). A room with frosted glass installed is not dark during the day, but the inside and outside of the glass cannot see the opposite scene clearly. It can also be high transmittance and low haze (such as ordinary glass) , which can maintain brightness while seeing the inside and outside scenes clearly.

In practical application:

High light transmittance and low haze materials are suitable for applications requiring high clarity, such as display screens or car window glass.

high light transmittance and high haze are suitable for situations where light needs to be diffused, such as some lampshades or soft light sheets, which can transmit light while avoiding the glare of direct light.

When is it necessary to measure haze? Applications of haze

Haze is an important indicator for measuring the optical properties of transparent or translucent materials, reflecting the degree of light scattering by the material. The measurement and control of haze is crucial in many industries, with the following specific applications:

1. Haze in Plastics and Film Manufacturing
  In the plastics and film industries, haze is used to evaluate the clarity of transparent and translucent materials. For example, food packaging films and optical protective films require controlled haze levels to ensure both product protection and clarity.

2. Haze in Glass and Building Materials
  Glass curtain walls, automotive glass, and privacy glass all have specific haze requirements. Low-haze architectural glass provides clear visibility, while privacy glass may require higher haze to limit clarity.

3. Haze in Semiconductor and Optical Device Materials
  In semiconductors and electronic components, haze measurement helps assess material purity and structure. Semiconductor materials and optical lenses have high haze standards, particularly in high-precision applications like sensors, cameras, and fiber optics, where low haze enhances transparency and optimizes optical performance, ensuring clear and accurate light transmission.

4. Haze in Packaging Design
  The haze of packaging materials for food and cosmetics directly impacts product presentation and visual appeal. High-haze packaging can obscure contents for a sense of mystery, while low-haze packaging enhances transparency.

5. Haze in Lighting and Fixtures
  Diffuse light covers or translucent materials in lighting fixtures usually feature high haze to scatter light, providing softer illumination and preventing harsh glare, making them suitable for home and commercial lighting.

6. Haze in Electronic Device Displays
  Screen materials for mobile phones, tablets, computers, and TVs often require high transparency and low haze to ensure clarity and user experience, avoiding blurring and glare from light scattering.

7. Haze in Automotive Manufacturing
  Automotive components, including plastic parts, light covers, and windshields, need controlled haze to ensure clear and stable light transmission, enhancing safety and driving experience.

Haze standards and specifications

International standards and specifications for haze are designed to provide consistent test methods and reference standards for haze measurement of different materials, ensuring that measurement results are comparable worldwide. Here are some of the main international haze standards:

ISO International Standards

ISO 14782:2021 - Plastics — Determination of haze for transparent materials
This standard provides a standardized test method for the haze measurement of transparent plastic materials and is suitable for the evaluation of the optical properties of various types of transparent plastics.

ISO 13468-1:1996 and ISO 13468-2:1999 - Plastics — Determination of the total luminous transmittance of transparent materials
These two standards specify the measurement methods for the total transmittance and haze of transparent plastics and are mainly used for transparent materials with high optical requirements.

ASTM International Standards

ASTM D1003-13 — Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics
This is a commonly used standard of the American Society for Testing and Materials. It is widely used in the plastics industry to measure the haze and transmittance of transparent plastics. It is one of the internationally recognized haze test methods.

ASTM D1044 — Standard Test Method for Resistance of Transparent Plastics to Surface Abrasion
Although this standard is primarily used to evaluate the abrasion resistance of transparent plastics, its test method also involves the measurement of haze changes.

JIS Japanese Industrial Standard

JIS K 7105 —Determination of light transmittance and haze of transparent plastics
This standard provides the test method for light transmittance and haze of transparent plastics and is applicable to Japanese plastic products that need to evaluate optical properties.

DIN German Standard

DIN 5036-3 — Radiometric and Photometric Properties of Materials; Diffuse Transmission
The German Industrial Standards section dealing with optical measurements also covers methods for measuring haze, particularly with regard to the light scattering properties of transparent materials.

Chinese Standards (Related International References)

GB/T 2410-2008 and GB/T 5132-2009
Chinese standards GB/T 2410-2008 and GB/T 5132-2009 regulate the haze and transmittance of transparent materials. These standards were formulated with reference to ISO and ASTM standards and have international applicability.

How to measure haze? Methods of haze measurement

The main methods for measuring haze include using a haze meter and a spectrophotometer , which can evaluate the degree of light scattering of a material through different technical means. The following are two methods for measuring haze with two instruments:

1. Haze measurement with haze meter

A haze meter is a device specifically used to measure haze. It uses an integrating sphere system or a photoelectric detection system to directly read the haze value. During measurement, the light source shines light onto the sample, and the device calculates the proportion of scattered light that deviates from the direction of the incident light, which is the haze.

3nh haze meter structure

Advantages : fast, convenient, high precision, especially suitable for measuring the haze of transparent or translucent materials in flat, sheet and film form.
Typical standards : ASTM D1003, ISO 14782 and GB/T 2410.

2. Measuring haze using spectrophotometer

Spectrophotometer can measure the transmittance and scattering of materials to light of different wavelengths, and is used to analyze the distribution of transmitted light and scattered light. The measurement methods of spectrophotometer include the following:

Direct method : Place the sample between the light source and the detector and measure the intensity of the transmitted light. The haze is then calculated by calculating the proportion of scattered light.

Integrating sphere method : Place the sample at the opening of the integrating sphere and evaluate the haze by measuring the reflected light and scattered light at different angles on the inner wall of the integrating sphere.

Advantages : Spectrophotometers can measure light scattering at different wavelengths, provide more detailed spectral information, and are suitable for situations where precise analysis is required.
Typical applications : In the field of optical devices and semiconductors, tests with higher accuracy and wavelength resolution are usually required.

3nh Benchtop Spectrophotometer YS6002-M

3. Measurement standards and conditions

Haze measurement usually follows standards such as ASTM D1003 and ISO 14782 , which specify the type of test light source (such as C light source, D65 light source) and the detection angle. The standard requires measurement under specific light sources and angles to ensure comparability and accuracy of the results.

4. Steps for haze measurement (taking 3nh haze meter as an example)

1. Calibration equipment : According to the standards followed, use standard sheets to calibrate the haze meter to ensure the accuracy of the instrument's measurements. The following are the things to note during calibration:

0% calibration: During calibration, use the 0% calibration cover to block all light from the instrument's light source entering the integrating sphere, and the instrument collects dark signals.

100% calibration: Users can select the corresponding 100% calibration reference according to different types of transmission samples to be tested.

Normally, if the sample to be tested is plastic, glass, transparent film, etc., air can be selected as the 100% calibration reference. If the sample to be tested is a liquid , a cuvette filled with deionized water or distilled water can be selected as the 100% calibration reference; if the sample to be tested is a powder in colorimetric blood , empty colorimetric blood can be selected as the 100% calibration reference. Of course, users can also select a calibrated standard solution (such as a potassium permanganate solution with a calibrated transmittance ) as the 100% calibration reference (the calibration parameters must select the corresponding calibration channel).

2. Place the sample : Fix the sample between the light source and detector of the haze meter, making sure the sample is flat and free of dust and dirt.

3. Read data : Start the device and read the haze value directly, or obtain the transmission spectrum data on a spectrophotometer and calculate the haze.

4. Data Analysis : For precise measurements, spectrophotometer data may require further analysis to obtain haze distribution at different wavelengths.

3nh haze meter measurement results interface, T represents transmittance, H represents haze

Precautions

· Environmental requirements : Ensure that the light source, temperature and humidity of the test environment are stable to avoid affecting the measurement accuracy.

· Sample preparation : The sample needs to be clean and scratch-free to ensure that the measurement results are not affected by contamination and surface defects.

Through these methods, haze measurement can accurately evaluate the optical properties of transparent or translucent materials and provide a reliable basis for product quality control.

3nh Haze Meter

3nh offers a range of haze meters designed to measure the haze and transmittance of transparent and translucent materials. Here are some of their key models:

YH1200 Haze Meter: This instrument supports both ASTM D1003 non-compensation and ISO 13468 compensation methods for full light transmittance and haze testing. It features an open sample chamber suitable for vertical and horizontal testing, accommodating various sample types. Equipped with a PD array detector , it aligns with the CIE V(λ)2 degree visual response, ensuring high precision and repeatability in measurements.

3nh YH1200 Haze Meter

YH1210 Haze Meter: Similar to the YH1200, the YH1210 offers enhanced features, including a large touch screen for easy operation and dynamic measurement capabilities. It utilizes a PD array detector to meet the CIE V(λ)2 degree visual response, achieving high precision and repeatable transmittance and haze measurements.

YH1810 Color Haze Meter: This advanced model not only measures haze and transmittance but also provides color measurement capabilities. It offers multiple observation light sources and color spaces, catering to specialized measurement needs under different conditions. The YH1810 is equipped with a large touch control screen and a 256-pixel dual array CMOS image sensor for high accuracy and repeatability.

3nh YH1810 Color Haze Meter

These haze meters are widely used in industries such as glass processing, plastic manufacturing, film production, display screen manufacturing, packaging, and liquid analysis. They assist in ensuring product quality by providing precise measurements of haze and transmittance.

For more detailed information on these products, you can visit 3nh's official website or contact our customer support.