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2025-02-24
Haze and transmittance are important optical performance indicators of transparent materials. The former is used to characterize the irregular state of transparent materials, such as fog or chaos, while the latter is used to characterize the ability of light to penetrate the material medium. It can be measured using a haze meter. So, what is the relationship between haze and transmittance? Do haze and transmittance have units?
Transparent Materials
Haze is the ratio of the scattered light flux that deviates from the direction of parallel light when parallel light enters a transparent object to the total transmitted light flux. The haze unit is expressed in percentage. Transparent materials generally refer to materials with a haze value H between 0-30%. Common transparent materials include plastics, float glass, tempered glass, acrylic panels, etc.
Transmittance refers to the ability of light to pass through a material object medium, which is the percentage of the luminous flux passing through the material medium to its incident luminous flux. Transmittance is also an important parameter of the optical properties of transparent or translucent materials.
Transparent Materials
From the concept of haze and transmittance, we find that haze and transmittance have little to do with each other. However, haze and transmittance still have some very clever connections. The connections between haze and transmittance are:
(1) Both involve the transmitted luminous flux of light.
(2) Both are only on transparent/translucent materials with haze and transmittance requirements.
(3) Generally speaking, the higher the light transmittance of a material, the lower its haze; and the higher the haze of a material, the lower its light transmittance.
(4) Instruments that can measure haze can also measure transmittance.
(5) A haze meter can also be called a haze meter, a transmittance meter, or a transmittance tester.
(6) People may have requirements for materials with high light transmittance and high haze, such as diffusers.
Haze: Measures the light scattering properties of a material. Haze can be attributed to suspended particles or contaminants in the sample, or fine surface texture versus contamination. Haze measurements can be used to quantify the optical properties of plastics and packaging films. Hazy films in packaging applications can reduce consumer quality perception, such as the packaged product appearing hazy. For plastics with haze, visibility of the test material becomes more noticeable and reduces the contrast of observed objects.
Transmittance: A measure of the total amount of light that passes through a material, affected by absorption and reflection properties. In the plastic film industry, transmission measurements are related to the opacity of the material and/or the hiding power of an applied coating.
Haze is the percentage of the transmitted light intensity that deviates from the incident light by more than 2.5° to the total transmitted light intensity. The greater the haze, the lower the gloss and transparency of the film, especially the imaging. Haze is an important parameter for the optical transparency of transparent or translucent materials. Since haze represents the percentage of the transmitted light intensity that deviates from the incident light by more than 2.5° to the total transmitted light intensity, the greater the proportion of scattered light, the greater the haze of the material, that is, haze = scattered transmitted light / transmitted light. From this, we know that the unit of haze is also a percentage.
When a parallel beam of light passes through a transparent or semi-transparent material, part of the incident light will be reflected and absorbed by the material, and part will pass through the material to form parallel transmission and diffuse transmission. Parallel transmission and diffuse transmission characterize the ability of the material to transmit light, that is, transmittance = (parallel transmission light + diffuse transmission light) / incident light. From this, we know that the unit of transmittance is percentage.
Haze meter measures haze and transmittance
In order to accurately measure the transmittance and haze of transparent materials, we can use a haze meter. There are many types of haze meters on the market, and the YH1810 color haze meter is one of the more useful ones. It is composed of the light emitted by the full-spectrum LED lamp, which is converged by a condenser, and then shot onto the objective lens through a light bar and a shading modulator to produce a parallel light beam, and the light bar is imaged on the exit window. There is a swingable standard reflector in the integrating sphere. When measuring the transmittance and total transmittance, the standard reflector is controlled in place to block the exit window; when measuring scattered light, it moves away from the exit window. The haze, transparency and other data of the LCD screen can be accurately measured. The specific steps are as follows:
1. Sample Preparation
Prepare a representative sample of transparent material and prepare the surface.
2. Choose a measurement standard
There are two commonly used standards for haze meter testing: ISO and ASTM. We select the standard that meets our measurement needs before completing subsequent measurements.
3. Instrument Calibration
The haze meter is also an optical instrument. Since it is an optical instrument, we need to calibrate it when using it. The calibration of the haze meter is very simple. Select the corresponding calibration function and then follow the prompts of the instrument to complete the calibration.
4. Instrument measurement
When measuring, you need to consider whether the size and thickness of the transparent material meet the measurement requirements. At present, some Sanshi haze meters can be placed vertically or horizontally for measurement, and the measurement method can be selected as needed. When measuring, place the transparent material in the measurement port and then press the button to measure.
5. Value Analysis
After the measurement is completed, the light transmittance value of the material can be reached. By comparing this value with the target value, we can get the result we need to process.
