Altana Micro-Haze Plus Manual do Utilizador descarregar pdf (Página 38)

Measuring Principles 10

When light is reflected on systems

containing pigments, such as

paints, varnishes or plastics, a part

of the illuminated light penetrates

into the material and is scattered

diffusely at the pigments. The

measuring unit comprises an addi-

tional detector to compensate for

this scattered light which is not

caused by the surface (brightness

compensation).

In order to take into consideration

the human perception of haze the

haze values normally are indicated

logarithmically. The logarithmic

haze value is calculated from the li-

near intensity of the scattered light

according to the following formula:

H = K·lg ( + 1)

The constant (K=1285.1) has been

calculated such that a logarithmic

value of 1 000 is obtained for a li-

near haze of 100. Two different

displays can be selected to display

the measured values:

Hlog – logarithmic scaling with

brightness compensation

Hlin – linear scaling without

brightness compensation

The setting Hlin, however, is only

used in very specific applications

(highly scattering surfaces without

pigments).

The calibration data always relates

to the linear haze value without

brightness compensation.

Hlin

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Altana Micro-Haze Plus Manual do Utilizador Página 38