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OBS500 Smart Turbidity Meter with ClearSensor
®
Technology
11
and at 90° for the sidescatter measurement. A 3D schematic of the main
components of the sensor is shown in FIGURE
. The OBS500 light source
is a Vertical-Cavity Surface-Emitting Laser diode (VCSEL), which converts
5 mA of electrical current to 2000 μW of optical power. The detectors are low-
drift silicon photodiodes with enhanced NIR responsivity. NIR responsivity is
the ratio of electrical current produced per unit of light power in A/W. A light
baffle prevents direct illumination of the detector by the light source and in-
phase coupling that would otherwise produce large signal biases. A daylight-
rejection filter blocks visible light in the solar spectrum and reduces ambient-
light interference. In addition to the filter, a synchronous detection circuit is
used to eliminate the bias caused by ambient light. The VCSEL is driven by a
temperature-compensated Voltage-Controlled Current Source (VCCS).
FIGURE 5-2. Orientation of emitter cone (source beam) and OBS and
sidescatter detector (acceptance) cones
The beam divergence angle of the VCSEL source is 4° worst case and 2°
typical
(95% of the beam power is contained within a 5°
cone).
6. Specifications
Features:
•
Dual backscatter and sidescatter sensors used to measure turbidity
•
ClearSensor
®
antifouling method for better measurements in
biologically active water
•
Shutter/wiper mechanism keeps lenses clean
•
Refillable biocide chamber prevents fouling
•
Disposable plastic sleeve facilitates cleanup
•
Optional copper sleeve for additional protection (especially for sea
water) or disposable plastic sleeve facilitates easy cleanup
•
Compatible with Campbell Scientific CRBasic dataloggers: CR6,
CR200(X) series, CR800 series, CR1000, CR3000, and CR5000.
Dual Probe:
Backscatter and 90-degree sidescatter
TU Range:
0 to 4000 TU
Active and Passive Antifouling:
Shutter, wiper, biocide, copper, optional
removable sleeve
Emitter Cone
OBS Detector
Cone
90° Sidescatter
Detector Cone
Содержание OBS500
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Страница 10: ...Table of Contents iv ...
Страница 15: ...OBS500 Smart Turbidity Meter with ClearSensor Technology 5 FIGURE 4 4 Place and secure mounting fixture ...
Страница 58: ...Appendix B Example Programs B 6 ...
Страница 60: ...Appendix C OBS500 Copper Sleeve Kit Installation C 2 ...
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