A LIGHT-INTENSITY FUNCTION SUITABLE FOR MULTIMODE FIBEROPTIC SENSORS

Intensity distribution functions on the image plane are derived when assuming a multimode optic fiber is illuminated by a light source which can be approximated by infinite uniangular beams carrying equal power. The application of the theory to a Lambertian source is discussed. Experimental results, based on the observation of the light intensity distribution imaged on an opaque screen and collected by a digital camera, are presented when a multimode fiber is illuminated by a light emitting diode. The theoretical and experimental data are compared to verify the intensity function as an accurate model in describing the realistic approach to sensor design. The limitations of the uniangular and uniform intensity distribution models are discussed based on our theoretical and experimental results.