Raman Spectroscopy chemical "fingerprinting" of dissolved water contaminants.
Raman spectroscopy is a standard chemistry technique for detecting chemicals dissolved in water samples, which we apply to aquaculture systems. We tailor our sensitivity requirements to provide lower cost systems.
Our general path is to take a water sample (few cc's) from the fish tank. Then we shine continuous (CW) temperature controlled diode lasers (red, green, blue) onto this sample and with additional optics collect the scattered light. We use various visible light detectors: photo diode, avalanche photo diode, silicon photo multipliers for various light intensities, combined with a folded monochromator whose wavelength dispersive grating is rotated by a small stepper motor. The electronics are developed in-house. A typical use will be to quantify organics, ammonia, nitrates or nitrites in the water.
As we understand measurements taken CW laser sources, we will work with short (nanosecond) pulsed lasers to minimize interference from fluorescent signals [Ref: Norman/Ruud/Saue book] . The data acquisition system will sample every 200 pS, during and just after the laser pulse.
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