{Object in turbid eater}

MJC Optical Technology expertise: Software development example

Radiative transfer theory permits simulation of image transmission through turbid media such turbid water and human tissue. This image set, generated by software developed by MJC, simulates imaging of a test pattern (left) in turbid water by two underwater imaging systems: a conventional system (middle) and a range-gating system (right). The conventional system produces an essentially undiscernible image of the pattern, while the range-gated system produces a fairly recognizable image under the same conditions.

Range-gated imaging improves image resolution by excluding most of the image-blurring light backscattered by turbid medium. At meter distances, for example in turbid water, this is done by illuminating a scene with nanoseconds-long light pulses and viewing it only within a gate period that is comparable to the pulse duration and opens when each pulse returns from the object. This is referred to as range-gating. The term "range" reflects the gate delay dependency on the object distance (range) from the imager. A gated detector records only light reflected by the object and backscattered by a thin illumination zone near the object. Light backscattered by most of the scene medium arrives at the detector when it is switched off. That light is excluded from forming the image. At millimeter distances, for example in human tissue, range-gating can be implemented with optical coherent tomography (OCT).

The images are published with permission of a client.

© 2001 MJC Optical Technology