Explanation of haze, transmittance, refraction and glossiness

Generally speaking, we can understand the concept of haze as the ability to scatter light. As shown above, light is scattered.
The greater the haze, the stronger the material’s ability to scatter light, and the more blurred our eyes will be. For example, frosted glass, standing at the other end of the glass, the human eye can not see the scene on the other side of the glass, but the glass is transparent. (The wall can’t see the other side, but the wall blocks light.)

In the mobile phone and automobile industry, it is often necessary to measure the haze parameter.
The written explanation is: the ratio of the scattered luminous flux passing through the sample and deviating from the direction of the incident light to the transmitted luminous flux, expressed as a percentage. Generally, only the scattered luminous flux that deviates more than 2.5 degrees from the direction of the incident light is used to calculate the haze.

The transmittance is relatively easy to understand. It can be understood as the ability of light to penetrate the material, which has nothing to do with the direction of light transmission after transmission. The higher the transmittance, the more light passes through. For example, glass windows and curtains are required to be transparent, and curtains are required to be as opaque as possible.

With the advent of the intelligent era and the rise of the touch screen, the transmissivity of many materials began to have high requirements. Many materials began to need to test the transmissivity, and often, the transmissivity and haze generally need to be tested at the same time.

For the transmittance, the written interpretation is: the ratio of the luminous flux passing through the sample to the luminous flux emitted on the sample, expressed as a percentage.

We are familiar with the refraction of light. What is the difference and connection between haze and refraction?
Refraction is a kind of light passing through a certain medium, the direction of propagation will change. The change of this angle is certain. From the perspective of sensory experience, it is still able to see the opposite scene clearly, but the position has changed. The real example is that the chopsticks bend in the water, but the underwater part still looks like chopsticks.

However, haze can be understood as light scattering due to refraction in different directions due to materials. In this case, the opposite scene can not be seen clearly.

Rigorous description of refraction: When light slants from one transparent medium to another, the propagation direction will generally change. This phenomenon is called light refraction.

Glossiness is actually a completely different concept from the above three. The above three are transmission phenomena for transparent objects, and glossiness is the specular reflection of light on the surface of the object.
Glossiness can be understood as the fine “roughness” of the object surface. The smoother the surface, the more “reflective” it is, the more “bright” it is to the human eye, and the higher the glossiness.
There are a wide range of industries that need to measure glossiness. Generally, glossmeter is used.

Written explanation: glossiness is a physical quantity to evaluate the ability of the material surface to reflect light specularly.

LISUN’s solution for haze, transmittance and transmittance measurement:
Features of haze meter:
Haze is the percentage of transmitted light intensity that deviates from the incident light by more than 2.5 ° to the total transmitted light intensity.
Transmittance (T) refers to the percentage of luminous flux passing through transparent or translucent body and its incident luminous flux.

LISUN haze meter is applicable to the one-stop measurement solution of color, haze and transmittance of transparent and translucent materials such as plastic, film, glass, LCD panel, touch screen, etc.
1. Comply with ASTM and ISO haze measurement standards at the same time
2. Provide A, C and D65 measuring light sources for haze measurement
3. Provides color measurement function, measurement index and measurement light source
4. Open measurement area, free of sample size restrictions
5. 5.0 “TFT display screen with good human-computer interface
6. Provide haze, color and transmittance measurement and analysis software to meet the user’s analysis and management of test data

Introduction to the principle of haze meter:
Test principle:
During the test, when there is no incident light, the received luminous flux is 0%;
During the test, when the sample is not placed, the incident light is fully transmitted, and the received luminous flux is 100%, that is, T1;
At this time, the light trap is used to absorb the parallel light, and the received luminous flux is the scattered luminous flux T3 of the instrument;
Then place the sample, and the luminous flux received by the instrument through the sample is T2;
At this time, if the parallel light is absorbed by the light trap, the luminous flux received by the instrument is the sum of the scattered luminous flux of the sample and the instrument T4.
The transmittance and haze values can be calculated according to the measured values of T1, T2, T3 and T4.

Key points of the method:
1. 0% calibration and 100% calibration:
Note: During calibration, the operation of the compensation port should be selected according to the current selection standard. If it is an ISO standard, the compensation port cover cannot be closed, and the compensation port should be kept open; If it is ASTM standard, the compensation port shall be covered with the compensation port cover.
At 100% calibration, the incident luminous flux T1 and the instrument scattered luminous flux T3 will be obtained, and then saved for calculating the transmittance and haze.

2. ASTM Standards:
During the transmittance test, the sample is placed at the test port, and the dial is automatically moved to the optical trap to block the optical trap. After testing once, the transmitted luminous flux T2 is obtained.

During the haze test, the sample is placed at the test port, and the paddle is automatically moved to the optical trap to block the optical trap. After testing once, the transmitted luminous flux T2 is obtained, and then the paddle is automatically moved to the compensation port. After testing once, the instrument plus sample scattered luminous flux T4 is obtained.

3. ISO standard:
When testing the transmissivity, first place the sample at the compensation port, and then move the paddle automatically to the optical trap. Test once to obtain the incident luminous flux T1. Replace the T1 value calibrated by 100%. Then place the sample at the test port, and keep the paddle position unchanged. Test once to obtain the transmitted luminous flux T2.
During the haze test, the sample is placed at the test port, and the paddle is automatically moved to the optical trap to block the optical trap. After testing once, the transmitted luminous flux T2 is obtained, and then the paddle is automatically moved to the compensation port. After testing once, the instrument plus sample scattered luminous flux T4 is obtained.

Haze Meter and Spectrophotometer HM-700 is designed for color, haze, spectral transmittance and total transmittance measurement of transparent and translucent materials such as plastic sheets, films, glass, LCD panel and touch screen, etc.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

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Tags：HM-700