Non-homogenous illumination correction of calibrated incoherent optical-fiber-bundles for image transmission purposes

We present here a new non-homogenous illumination correction method of a calibrated incoherent optical fiber bundle (IOFB) for image transmission purpose. The use of IOFB for image transmission in hazardous areas, where conventional camera cannot be employed because of their incorporated electronic, is fully justified. The high fabrication cost of coherent optical fiber bundles makes IOFB useful for large distances images capture applications. Since the bundle is spatially incoherent, the image coming out at the bundle end is a random set of illuminated points, without any spatial correlation, but once the IOFB calibrated, it can be used to transmit optical images without any electronics. To calibrate such cables, a flat LCD screen is used to emit input images. To solve a chromatic aberration problem, generated by the optical system composed by few conventional lens, diaphragms are used, which also reduce the emitted light, and so solve the saturation camera sensor problem too. It unfortunately generates a non-homogenous output picture illumination, which creates noise in the reconstructed images. In this paper we present and compare three methods to correct the cable output image illumination, once the spatial calibration is achieved, presenting some of the results obtained using this method