FIBER-OPTIC-GRADED-INDEX-LENS ABSORBENCY SENSOR WITH WAVELENGTH-SCANNING CAPABILITY

A single optical-fiber absorbance sensor that contains a graded-index lens is described. The sensor can be tailored for a desired broad wave length region, path length, and size. Laboratory evaluations of sensor s of varying sizes and path lengths are presented. The sensors, even w ithout the added expense of optical coating, report true absorbance sp ectra for the 420-850-nm wavelength region with a linear response over a wide absorbance range. Direct comparison with several other sensor configurations shows that the graded-index-lens-band sensor has a high optical efficiency. Potential applications of the sensor include abso rbance measurements at hazardous or remote sites and in vivo medical a pplications.