What is a haze meter

What is a haze meter?

A haze meter, also known as a haze tester, is used to determine the optical properties of transparent and translucent parallel planar materials and plastic films. A haze meter is an optical instrument; it is not a measuring weather device. What people call haze, is also called turbidity. Transparent materials are produced in such a way that a cloudy or hazy appearance occurs inside or on the surface of the material due to light scattering. Haze can be expressed as a percentage of the ratio of the scattered light flux to the light flux through the material, and usually only the scattered light flux that deviates more than 2.5 degrees from the direction of the incident light is used to calculate haze.

To put it simply, haze is the degree of haze of transparent materials, in different scenarios, people on plastic, glass material products haze requirements are different, in order to accurately assess the haze of the product, you can use a professional haze meter to measure.

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Understanding the difference between haze, transmittance and gloss

In layman’s terms, we can understand the concept of haze as the ability to scatter light. As the above diagram shows, light is scattered.
The greater the haze, the stronger the material’s ability to scatter light, and the less visible it is to our human eyes. For example, frosted glass, standing at the other end of the glass, the human eye cannot see the scene on the other side of the glass, but the glass is able to transmit light. (The wall can’t see the other side either, but the wall blocks the light.)
In the cell phone and automotive industry, many times need to measure the parameter of haze.

The written explanation is: the ratio of the scattered light flux through the specimen and deviated from the direction of the incident light to the transmitted light flux, expressed as a percentage. Usually only the scattered flux that deviates from the direction of the incident light by more than 2.5 degrees is used to calculate haze.

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Okay, let’s move on to the next transmittance to explain. 
Transmittance is relatively well understood, and can be understood as the ability of light to penetrate the material, and has no relationship with the direction of light propagation after transmission. The higher the transmittance, the more light is transmitted. To give an extreme example, that is, glass windows and curtains, glass windows require light transmission, curtains require as much as possible not to transmit light.
The advent of the age of intelligence and the rise of touch screens began to have high requirements for the transmittance of many materials, and many materials began to require testing for transmittance, and often, transmittance and haze are generally required to be tested at the same time.

For the transmittance, the written explanation is: the ratio of the luminous flux through the specimen to the luminous flux shot onto the specimen, expressed as a percentage.

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Let’s move on to gloss, which is considered by many of our industries. 
Glossiness is actually a completely different concept from the above two, the above three are for the transparent object transmission phenomenon, while glossiness is for the surface of the object for the specular reflection of light.
Glossiness can be understood as the subtle “roughness” of the surface of the object. The smoother the surface, the more “reflective” it is, the brighter it is to the human eye, and the higher the gloss.
The industry that needs to measure gloss is very wide, generally are using gloss meter.
Written explanation: gloss is a physical quantity that evaluates the ability of a material surface to reflect light specularly.
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The working principle of haze meter

Absorption of light by plastics. Scattering is related to the structure of the material itself. Surface characteristics and other substances contained in it. The determination of light transmission and haze of transparent or translucent plastics can be used to control product quality and to study certain optical properties of products. Haze of plastics is the ratio of the scattered light flux to the transmitted light flux through the specimen that deviates from the reverse of the incident light, expressed as a percentage. Haze is due to surface defects in the material. Density changes or light scattering impurities caused by the material internal or surface due to light scattering caused by the cloudy or cloudy appearance, so haze is also known as turbidity. It is used to measure the degree of unclearness of transparent or translucent materials.
Generally speaking, materials with high light transmission have low haze values; conversely, materials with low light transmission have high haze values, but this is not entirely true. Some materials with high light transmittance have large haze values, such as wool glass, so light transmittance and haze values are two independent indicators. In industry, the haze of plastics will be measured using an integral solver haze meter or integral solver photometer. The principle is to use the measurement of the amount of incident light, the total light transmission through the specimen, the amount of light scattering caused by the instrument and the amount of light scattering caused by the instrument and the specimen together to calculate the total transmittance through the specimen Tt. Slow scattering transmittance Td and haze (Td/Tt).
A parallel beam of light incident on a medium (such as transparent plastic), due to the inhomogeneity of the optical properties of the material; surface defects, internal organization of the inhomogeneity, the presence of bubbles and impurities, etc., the beam will change direction (diffusion and deflection), resulting in a part of the disordered light called scattered light.
International regulations with through the specimen and deviated from the direction of the incident light scattered light flux and the ratio of transmitted light flux expressed as a percentage, which is called haze. The specimen with large haze will give a more blurred feeling.
Light through the specimen will also produce losses, that is, the transmitted flux of light through the specimen is always less than the incident flux of light hitting the specimen. The ratio of the two, expressed as a percentage, is internationally defined as the light transmission rate. The reason for the decrease in transmittance is the reflection of light from the two surfaces of the specimen and the absorption of light energy at the full or partial wavelength of the incident light by the specimen.
But note: haze and light transmittance are two concepts. The material with high haze can be not very low light transmission. If you use such a material for window glass, the room appears bright during the day, but hidden; if you do car windshields, that obviously requires both to be good for true observation.
In the process of testing the haze and transmittance of the sample, the incident luminous flux (T1), transmitted luminous flux (T2) must be measured. The scattered luminous flux of the instrument (T3), the scattered luminous flux of the specimen (T4). Then the transmittance and haze values are calculated as follows.

  • Light transmittance: Tt=T2/T1×100%
  • Haze: H=T4/Tt×100%

Test, no incident light, the accepted luminous flux is 0, when there is no specimen, the incident light all through, the accepted luminous flux is 100, that is, T1. At this time, and then use the light trap to absorb the parallel light, the accepted luminous flux is the scattered luminous flux of the instrument T3; then place the sample, the instrument accepts the transmitted luminous flux is T2, at this time, if the parallel light is absorbed by the light trap, the instrument accepts the luminous flux of According to the measured values of T1, T2, T3 and T4, the transmittance and haze values can be calculated.

Application of haze meter

The haze meter can be used to measure solid samples such as agricultural packaging. Automotive aerospace. Architectural decorations. Photographic films. Projection screen and other related transparent. Translucent media. Can also be used for the determination of turbidity of liquid samples: such as the determination of turbidity of coloring liquids in the chemical industry, grease. Determination of turbidity of solvents, textile. Thermoelectricity. Steel. Light bulbs. Semiconductor. Paper making. Synthetic fiber and other industrial water testing, as well as environmental protection departments of sewage treatment quality inspection, tap water. Soda. Beer. Sugar. monosodium glutamate. MSG. condiments and other enterprises edible water. In pharmaceutical and clinical applications, it is also possible to determine trace solids in crystalline mother liquor. Concentration of substances, bacteria concentration. Blood clinical assay. Clarity of drugs, etc.

Classification of haze meter

The current fog meter mostly uses integrating sphere type.
The light emitted by the tungsten halogen lamp 1 convergence through the concentrator 2, through the light bar 3, through the shaded modulator 4 shot to the objective 5, the objective 5 shot a parallel beam, its light deviation angle is not more than 3 °, and the light bar 3 imaging on the exit window 10, the exit window to the center of the incident window opening angle of 8 °, the edge of the spot and the exit window to form a 1.3 ° ring band. Integrating sphere 7 is equipped with a swingable standard reflector 9, which is controlled in position to block the outgoing window when measuring transmittance and total transmitted light; when measuring scattered light, it gives way from the outgoing window.

Selection guide of haze meter

  • 1. Choose single- or dual-beam. Dual-beam is more than a single beam more light path, this extra beam is used to detect the stability of the light source and the external environment, if there are changes, this beam or compensation or correction.
  • 2. What standard of haze meter is used. Haze measurement has two main standards, ASTM standards and ISO standards, the difference is whether there is light compensation.
  • 3. Compare the standard plate performance. Standard plate can be compared to a mirror, we can see the appearance through the mirror. If there is a problem with the quality of the mirror, the reflected image will change. The traceability of the fog plate is a major criterion to reflect the good or bad of the fog plate, the authoritative traceability of the fog plate in the fog meter industry is NPL (National Physical Laboratory), whether by NPL traceability is also a criterion to examine the good or bad of the fog meter.
  • 4. Try to choose a larger production enterprise. Good after-sales service companies or sellers, which is the future maintenance of machinery. Maintenance has the benefit.

Maintenance of the haze meter

  • (1) The instrument should be placed in a dry and clean room, especially attention should be paid to humidity. Smoke on the impact of haze, avoid direct sunlight and electromagnetic field interference.
  • (2) The measured sample surface should be kept clean, if necessary, wipe clean with solvent or detergent, dry, or use a soft pen to remove the dust; randomly attached to the haze sheet for surface scattering treatment, susceptible to moisture. Humidity. Oil. Dust and other effects, cleaning with a cotton ball with distilled water, respectively. Alcohol. Banana water repeatedly lightly wipe several times, the data no longer change, that is, the cleaning is complete.
  • (3) It is recommended to warm up at least 20min when the machine is turned on.

Notes on the haze meter

Calibration of the fog meter

1. Calibration conditions: use the haze standard film at a temperature of (20±5)℃, relative humidity of <85% RH, no corrosive gases in the room. No strong electromagnetic interference. No strong vibration. No direct sunlight in the calibration environment, the zero point drift of the transmittance / haze meter. Value drift. Calibration of zero point drift, value drift, value error and measurement repeatability.
Note: The haze standard is very sensitive to the environment, especially the ambient humidity has an important effect on it. If the humidity is high, the surface of the standard will easily fog up (and cannot be wiped at will), which will cause the degree to deviate from the normal value and will directly lead to the deviation of the instrument. The relative humidity of the operating environment specified in the specification is not more than 80%. If the fogging film is placed in an environment with humidity close to 80% RH, the surface will fog up. It is recommended that the humidity of the operating environment must be strictly controlled, and that the calibration should be performed in a ventilated and dry environment. The calibration test should be performed in a dry environment to ensure the accuracy of the data.
2. Calibration methods.

  • ① The calibration method of zero point drift is to cover the light path with an opaque blackboard, measure every 2rain, and record the zero point value of light transmission and haze measured each time within 10min, and the difference between the maximum value of the reading and the minimum value is the zero point drift.
  • ② The calibration method of the indicated value drift is to measure the transmittance/haze standard every 2min, and record the transmittance and haze values measured each time within 10min, and the difference between the maximum value and the minimum value of the reading is the indicated value drift.
  • ③ The calibration method of the indicated value error is to use the transmittance / haze meter to continuously repeat the measurement of the transmittance haze standard film 10 times, the difference between the average value of the measurement and the standard value is the indicated value error.
  • ④ The calibration method of measurement repeatability is to calibrate the light transmittance of 90%. Haze is about 10% of the standard film continuous repeated measurement 10 times, 10 times the standard deviation of the measured value that is the light transmittance of the haze meter and haze measurement repeatability.

Haze meter troubleshooting

1. Light source tungsten halogen lamp does not light
Its fault for the tungsten halogen lamp is bad, the solution is to replace the tungsten halogen lamp. Open the back cover, loosen the two fixing screws on the tungsten halogen lamp, pull up the old lamp, replace the new lamp, tighten the screws. It is worth noting that the new lamp to take the application of paper wrapped, or wear cotton gloves and then operate to prevent handprints on. After replacing the tungsten halogen lamp must be readjusted to the instrument light path, filament height adjustment to the integration sphere at the incidence window spot uniform so that the light source from the tungsten halogen lamp can effectively pass through the spotting mirror. Light bar. Objective lens. Integrating sphere. Outgoing window. Incident window.
2. Standard reflector does not work
The fault for the circuit mechanical failure, the solution is to open the top cover, press the micro switch on the control board, if the board does not jump the light-emitting tube, the circuit board is bad. If the light-emitting tube jumping, then the mechanical transmission part of the card. Open the upper cover of the receiving system (right side), the transmission part of the investigation.

Operating procedures of the haze tester

1. Before testing and sample preparation
Make sure the instrument power supply wiring is correct, to meet the normal working environment of the instrument, the sample size should be 50mm * 50mm.
2. Power on
Press the power switch to turn on the power for preheating, after the preheating is completed, the window indicator will be prompted, and the user can further continue the calibration of the instrument.
3. Sample measurement
Put on the sample, put the film between the magnetic clamps and flatten it slightly, then you can put the device on the sample table for testing, when placing the clamps, you should pay attention to the film side against the integrating sphere. Press the test button, the indicator light turns red, and soon the transmittance value and haze value are displayed on the indicator screen, the former in 0.1% and the latter in 0.01%. At this time, the indicator light turns to green, when you need to retest, you may not take down the sample and press the test button again. Repeat TEST for the same batch of samples continuously.
4. Data processing
Multiple measurements, and then take the arithmetic mean for the measurement results, in order to improve the accuracy of measurement.
Notes on the use of the haze tester

  • 1. Generally, after measuring each group of samples should be measured blank once, it should be noted that after measuring the blank, you should press the test button again, wait until the preparation lamp glows green. After the instrument calls, then measure the next set of samples.
  • 2. The ambient temperature is 5-35°C and the relative humidity is not more than 85%.
  • 3. Non-operators are prohibited to operate.
  • 4. Ensure that the jack grounding wire is effective.
  • 5. If the test sample size is large, the sample holder can be removed, the product directly attached to the left side of the receiver for testing.
  • 6. The test requires that the center of the product be aligned with the center of the test hole as much as possible.

The difference between haze meter and turbidity meter?

In fact, this problem is very simple to explain, that is, the haze meter is mainly to measure the light through the medium when the parallel light deviated from the direction of incidence of the scattered flux and the ratio of transmitted flux, is used to assess the medium and light related to an important parameter; and turbidity is mainly the degree of turbidity of water, is the water contains a trace of insoluble suspended substances. The turbidity caused by colloidal substances, and light is not too related to remember the simplest difference between haze meter and turbidity meter can be, if you want to know more about the difference between haze meter and turbidity meter knowledge, we will continue to understand it.
1. The application industry of haze meter and turbidity meter is different.
Haze meter is mainly used in the industry of plastic. Glass. Film. Display processing and packaging industry. Liquid liquid analysis and other industries, and turbidity meter is mainly used in water plants. Power plant. Industrial and mining enterprises, mainly related to water quality and environmental protection and related laboratory analysis tests, most water plants are necessary turbidity meter.
2. Haze meter and turbidity meter measurement medium is different.
Haze meter relatively speaking, the measurement medium is more extensive, from plastic. Glass. Film. Display to packaging materials and pharmaceutical fluids can be, that is, the fog meter detection can be solid and liquid. And turbidity meter measurement medium is mainly water quality, is liquid. 
3. Haze meter and turbidity meter measurement principle is different.
Haze meter is to measure the ratio of the scattered flux of parallel light deviating from the direction of incidence to the transmitted flux, usually only the scattered flux of light deviating from the direction of incidence by more than 2.5 degrees is used to calculate the haze. And turbidity meter is the use of 90 degrees scattered light principle to calculate the degree of obstruction of light transmission occurred when the suspended matter in water.
4. Haze meter and turbidity meter internal optical system composition is different.
The optical system of turbidimeter consists of a tungsten filament lamp. Scattered light 90° detector. Transmitted light detector. Haze meter consists of 154mm integrating sphere. Concave grating. 256 pixel CMOS detector. 360~780nm combined LED light source composition.
5. Haze meter and turbidity meter price difference is very large.
Haze meter price is usually in tens of thousands of dollars, while the price of turbidity meter between a few hundred to a few thousand dollars, which can also be seen between the two haze meter and turbidity meter in the internal structure and optical components on the requirements and composition of the gap.
6. Haze meter and turbidity meter appearance and function are very different.
The appearance of the haze meter looks larger, also has a large color screen, the function of the haze meter can be in accordance with industry standards to achieve a variety of optical indicators (haze. Transmittance. Chromaticity. Chromatic aberration. Yellowness. Whiteness. (Cobalt-Platinum Index, Gardner Index, etc.) for accurate testing. The turbidity meter is usually smaller in appearance, and is capable of testing fewer functions.
7. Haze meter and turbidity meter external accessories are different.
Because of the many functions of the haze meter, there are many items and functional accessories that need to be tested, while the turbidimeter has relatively few external accessories. Of course, this is a relatively small difference.
Overall, the difference between haze meter and turbidity meter is still quite big, the two are completely two different instruments, the application of the scene is also different, the only point associated is for the light into the medium are measured after the value of scattered light flux.

How to buy the right haze meter?

1. Light source
LED light source fog meter than halogen lamp fog meter lower energy consumption, longer service life. Halogen lamp fog meter generally need to use 1-2 years to change the light source, LED light source fog meter ten years do not need to change the light source, so, LED light source is the future development direction of the fog meter industry.
2. Measurement time
In order to meet the efficient detection work, the instrument measurement time of the sample appears to be critical, especially to measure many samples, the measurement time is long, are very affect the efficiency of the work. The unique optical design of the haze meter SDR4080 makes its measurement time only 2 seconds, which greatly enhances the work efficiency.
3. Dual standards
There are two main standards for haze measurement, ASM standard and ISO standard, the difference is whether there is light compensation or not, the haze meter can manually select ASTM/ISO standard measurement according to the user’s requirements, which can meet all users’ standard requirements.
4. Sample bin
There are some brands of fog meter at home and abroad, their sample compartment is closed, which limits the size of the measurement sample and brings a lot of inconvenience to the testing work. Our haze meter adopts open sample compartment design, which frees the instrument from the limitation of sample size and ensures that the measurement results of the instrument are not affected by ambient light.
5. Large color screen display
Modern instruments are concerned with having a good human-machine interaction interface with clear and concise operation logic.
6. Conformity determination
With the progress of the economy, the enterprise requirements for product quality, the haze parameters as QC aspects of the detection trend is also becoming more and more obvious. So the haze meter to be able to set the haze value tolerance, compare the measurement results of the standard and specimen, a clear judgment of the measurement results of qualified and unqualified, which is a haze meter need to have the function.
7. Save data
Intelligent era, the focus is on efficient. Convenience, data testing. Save. View can be achieved in one machine, that makes the detection work much more convenient.
8. Data output port
At present, in many laboratories, the instrument needs to be connected to a computer to operate, and the staff wants the instrument to achieve mass storage of data and print test reports. Nowadays, without data output port, it is difficult to meet the requirements of users. Our haze meter comes with free computer data management software, which can connect the instrument to the computer and realize the computer side operation.
Source: China Haze Meter Manufacturer – www.spectrumgfa.com
www.spectrumgfa.com is one of the leading china Colorimeter & Spectrophotometer Manufacturer, with professional factory. We focus on the colorimeters, spectrophotometers, haze meters, gloss meters and spectral analysis instruments research and development, manufacturing, sales and service since the company been established. Our products is widely used on Painting,textile,plastic industry,food,building material and other products. 
If you want to have more information about the article or you want to share your opinion with us, contact us at sales@spectrumgfa.com

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