Fiber Optic Array Improves Spectroscopic Imaging

Michael D. Wheeler

Researchers from the University of South Carolina have created a fiber optic array that provides data in the spatial, temporal and spectroscopic dimensions. It may be useful in biomedical applications such as diagnosing cancer.

The fiber optic array designed by Nelson and Myrick provides data in the spatial, temporal and spectral dimensions of a laser plume.

Most spectroscopic applications involve the simultaneous measurement of one or two dimensions of data. Researchers routinely perform these measurements with photodiode or charge-coupled device (CCD) arrays. In certain cases, however, scientists require three dimensions of data.

One such application is studying the size, temperature and emission lines of the plume that results when laser light interacts with matter.

With this application in mind, graduate student Matthew P. Nelson and his adviser, Michael L. Myrick, designed fiber optic arrays that are two-dimensional at one end and one-dimensional at the other. Thus, an image presented at the 2-D end was reordered by row and column to the 1-D end. They used 600 closely packed, 250-µm-diameter optical fibers to fabricate an array the width of several human hairs.

Spark in view

To test their array, the researchers created a laser plume by aiming a 1064-nm Continuum Nd:YAG laser at a small lead solder target.

After the light passed through the array, a spectrograph dispersed it onto a thermoelectrically cooled Princeton Instruments 1100 × 330-pixel CCD camera. Software extracted spatial, spectral and temporal information.

The experiment yielded mixed results: The fibers were too large, and throughput to the array was only 1 percent.

If these problems can be solved, the device could enable the use of endoscopes in tumor diagnosis.