Optical Characteristics
An explanation of the meaning behind and the measurement method for the main physical properties measured.
Haze
| Unit |
% |
| Purpose / Details |
An index related to the transparency of the film that represents the amount of haziness (cloudiness). It is obtained from the ratio of diffuse transmitted light to the total light transmitted, and is affected by the amount of surface roughness. |
| Measurement Method / Standards |
In accordance with the former JIS-K-7105 and JIS-K-7136. |
| Specific Measurement Method |
Measured using a haze meter.
Haze (%) = Td/Tt × 100
Td: Diffuse Transmittance Tt: Total transmittance |
Total Transmittance
| Unit |
% |
| Purpose / Details |
This numerical value denotes the transparency of the film. |
| Measurement Method / Standards |
In accordance with the former JIS-K-7105 and JIS-K-7361. |
| Specific Measurement Method |
Represented by the total amount of light obtained with the haze meter used above. |
Whiteness
| Unit |
% |
| Purpose / Details |
This numerical value denotes the degree of whiteness of the film. |
| Measurement Method / Standards |
In accordance with JIS-L-1015. |
| Specific Measurement Method |
Measured using a color meter. There are two measurement methods: the Hunter Whiteness Index and the dual-wavelength method. |
Color Tone (L, a, b Values)
| Unit |
|
| Purpose / Details |
These represent the color tone of the film. The L-value represents brightness, the a-value is + for red and - for green, and the b-value is + for yellow and - for blue. The b value is often used for film. |
| Measurement Method / Standards |
In accordance with the former JIS-K-7105. |
| Specific Measurement Method |
Measured using a color meter. |
Optical Density
| Unit |
|
| Purpose / Details |
This value indicates light transmittance and is used for white and black type films. The higher the optical density, the lower the transmittance. When the transmittance is 100%, the optical density is 0. |
| Measurement Method / Standards |
Measured using an optical densitometer. |
| Specific Measurement Method |
Measured using an optical densitometer. A sample is irradiated by a vertically transmitted beam of light, and the ratio compared to the state without any sample is expressed by logarithm. |
