Field instruments afford means to examine the optical characteristics of natural objects in relation to its physical properties. In coastal shallow waters, the aim of remote sensing is to determine which physical attribute of the benthic cover and/or of the water, when sensed, is detectable and identifiable in an image.


The figure above shows that different types of benthic cover exhibit different spectral signatures

The algorithms to classify, quantify or segregate object components (such as concentration of different materials) in the water is based on the spectral property of the the object, expressed in terms of reflectance or radiance. The underlying presumption is that changes in spectral responses of objects are associated with the corresponding changes in the physical condition. For example, increase in sediment concentration would result in increase in its reflectance in the short visible wavelength.

In our laboratory, we have various in-situ optical measurement devices as follows:

Dual Spectrometer (Ocean Optics®) - this is actually a set of two spectrometers with optical range from 300 to 1150 nm at <1 nm spectral resolution. The dual configuration allows for simultaneous measurement of two spectral sets. In the water column, the upwelling and and downwelling

Recently we have just acquired a quartz cuvette filter and absorption measurement set to compliment this instrument which will determine absorption of water with 0.2mm-particles.

Vis-NIR Spectrometer (Spectra-Coop) - this spectrometer consists of two separable systems for visible and near-infrared systems. Aside from the fore-optics, the sensor itself is equipped with a tilt sensor and a camera/video system. The tilt sensor logs in the direction and viewing angle while the camera/video records an image of actual scope.

For both instruments, the sensor and the spectrometer module are attached by fiber-optic cables.