OBS-4 sensor measures suspended solids and turbidity

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Sediment Instruments for all Environments

OBS-4
Micro-size turbidity sensor

OBS-4 information sheet (136 kb Flashpaper)
OBS-4 information sheet (114 kb PDF)
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Features

Micro-size turbidity sensor
Custom OEM packaging
Low-power laser light source with automatic power control (APC)
Choice of 650, 780, or 850 nm operating wavelengths

Description
The OBS-4 sensor measures suspended solids and turbidity with a proprietary, laser-based light-scattering by ASTM Method 6677. It features nearly linear response to turbidity, a temperature coefficient < 0.05% per °C and extremely low drift with time < 2% per year.

Ranges
Turbidity		0-1,500 NTU
Concentration¹	Mud	0-500 mg/l
	Sand	0-15 g/l
¹ Range depends on sediment type.

Accuracy
Turbidity		0.2 NTU or 1% of reading, whichever is larger
Concentration	Mud	0.5 mg/l
	Sand	0.25 g/l

Other Data
Maximum data rate
Maximum data rate		10 Hz
Operating wavelength		650, 780, or 875 nm
Maximum depth		500 m
Drift		< 2% / year
Power		5 V / 10 mA
Housing Material		User specified
Day-light rejection		-13 to -28 dB (re: 48 mW cm^-1)

How do OBS and other optical sensors measure turbidity and suspended solids?

What light sources and detectors are used in OBS sensors?