YOKOGAWA UV700G, Руководство пользователя

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<2.Specification>
2-11
IM 12K01B02-01E
2.7 Measurement Principle
The rotary cell length modulation method, which combines high performance and reliability, is
adopted in this unit.
Two cylinder cells are placed, arranged with the light source and detector in a position where they
are decentered from the center of cylinder as shown in the figure below. By rotating these two
cylinder cells with the centers of the light source and detector as the rotation center, the distance
between the 2 cylinders (cell length) is modulated continuously and periodically. The signal input
to the detector from the light source is the signal which changes the difference in light intensity
between the maximum cell length (θ = 180 degrees) and the minimum cell length (θ = 0 degree)
into the amplitude. Wide range measurement becomes possible by selecting the optimum cell
length and calculating according to the change of cell length.
Rotation center of decentered cell
Center of light source
Center of cylinder cell
Rotation center of decentered cell
Center of detector
Output signal Cell length
θ
0°
90°
180°
270°
360°
θ=0 °
θ=90 °
θ=180 °
θ=270 °
θ=360 °
L1 L3
L1
L1
L2
L2
L3
l
Optical compensation
Optical compensation is attained by the rotary cell length modulation method. Information
required for optical compensation is the change of light intensity due to the light source, detector,
contamination of the measuring cell etc. This change in light intensity information can be obtained
by monitoring the light intensity when at the minimum cell length (θ = 0 degree).
l
Turbidity compensation (TURB)
This unit can measure ultraviolet (UV) and visible light (VIS) absorbances independently. UV-
αVIS display is possible by setting the turbidity correction factor (α), thus a more reliable turbidity
compensation can be performed.