Light transmittance meter with Integrating sphere effect

Transmittance is defined as the transmitted light intensity divided by the incident light intensity multiplied by 100%. Why do we need to divide the specular material and the milky white material in measuring the transmittance? The following uses LS117 light transmittance meter to test milky white material as an example.How to test the transmittance of opalescnet material?The LS117 light transmittance meter is based on the visual diffuse transmission density standard, and the two probes of the light source and the receiver are closely combined to receive all light including scattered light (Figure 3), so the transmittance will be higher, and This is accurate data.When a parallel incident light ray hits a rough surface, the surface will reflect the light in all directions, so although the incident rays are parallel to each other, the normal direction of each point is inconsistent, causing the reflected light to be reflected irregularly in different directions. This reflection is called "diffuse reflection" or "diffuse". This reflected light is called diffuse light. Many objects, such as plants, walls, clothes, etc., have rough surfaces that seem to be smooth, but if you look closely with a magnifying glass, you will see that the surface is uneven, so the originally parallel sunlight reflected by these surfaces Diffuse into different directions.
How to test the transmittance of opalescent material?Therefore, for the measurement of light transmittance of opalescent materials, mist materials, matte materials, etc., because of the diffuse transmission of light, it must be measured with the LS117 light transmittance meter.