6
Clarity is a scale used by traditional haze and clarity meters, when measured using
the 8mm adaptor plate Rhopoint ID Clarity measurements conform to specifications
written for these meters.
Inter-instrument Clarity agreement between Rhopoint ID and traditional sphere
instruments for commercial plastic films (<1000µm) is typically <0.4% C (SD).
Inter-instrument Clarity agreement between traditional sphere instruments and
Rhopoint ID for thick transparent plastic materials (<6mm) is typically <0.5% C (SD).
Waviness
this is an optical effect caused by large structures (0.1-2mm) on the surface
of the material. If the structure is homogeneous it is often described as orange peel-
the surface resembles the peel of an orange.
If the effect is anisotropic visible lines can often be seen when looking through the
material
Unlike sharpness these larger structures can cause dynamic distortion when the film
is moved over a target image/object which has straight edges- the edges appear to
distort and wave as the material is moved.
Waviness measures the visible distortion of the ID graticule edges through the
material- W is the standard deviation of the edge deformation in µm.
Waviness homogeneity is assessed by comparing W (average waviness) with W
H
(horizontal waviness) and W
v
(vertical waviness) using Rhopoint ID software.
Note: Sharpness and Clarity scales are only displayed on the instrument screen when
the ASTM Haze spacer is in place, to measure at varying distances the IDTX PC
software (provided with IDTX-L) must be used.
Transmission
: The Rhopoint ID measures VISIBLE TRANSMISSION- this is the
amount of light transmitted through the sample to be captured by the imaging camera.
The amount of light transmitted to the camera is dependent on the ID of the sample
and the separation distance.
Visible transmission is correlated to the perceived intensity of light reflected from a
viewed object when viewed through the sample.
Distance Dependence-
The Rhopoint IDTX-L (see note) can quantify this relationship
between distance and optical performance by measuring in contact or at defined
separation distances.
The ability of the IDTX-L to measure at definable separation distances means that the
suitability of materials for applications with different air gaps can be directly compared.