How do clear and diffuse sample spectra compare on a linear transmission accessory?

The figure here shows the measured results on the glass filter and opal glass. The transmission characteristics are clearly represented in the spectrum of a transparent sample, such as the glass filter. However, the transmittance is approximately 0 % for the opal glass which appears cloudy. The transmitted light for the opal glass is all scattered away at different angles due to the opaque nature of the sample.

If linear transmission measurements are performed on an opaque and translucent sample, some light is scattered in the sample as diffuse light and does not reach the detector. As the distance from the sample mounting position to the detector differs according to the type of spectrophotometer, the amount of diffuse light reaching the detector differs from instrument to instrument, even when the same sample is measured. Consequently, each instrument produces different measurement results. Total transmission measurements are also suitable for such samples.

The samples are displayed at bottom center.