invention contemplates the use of one or more cathode ray tubes as the light source in combination with any of the optical fiber arrangements discussed herein in the embodiment of fig8 cathode ray tubes 92 and 94 are mounted on the lower and upper housings 88 and 90 respectively for supplying the light sources required by the fibers mounted in display region 80 in a preferred form of the invention each of the cathode ray tubes 92 and 94 is provided with an aperture mask such as the mask 96 illustrated in fig9 associated with the face 98 of cathode ray tube 92 mask 96 is a sheet of opaque plastic or other suitable material perforated by a multiplicity of small closely spaced apertures 100 each aperture is adapted to receive the input tip 102 of an individual fiber strand such as the strands 70 of the double tapered bundle illustrated in fig6 the apertures 100 receive the input tips 102 and secure them in a predetermined position with respect to the face plate 98 thereby positioning these input tips in a predetermined matrix a similar mask is provided for cathode ray tube 94 so that by suitably controlling the deflection of the electron beams for the cathode ray tubes as by means of conventional deflection control circuitry 104 and 106 fig8 and by regulating the intensity of the electron beams by means of conventional intensity control circuits 108 and 110 the phosphor coatings on the interior surfaces of the cathode ray tube faces are selectively activated to produce light whereby the cathode ray tubes act as a controllable light source for each of the input tips the intensity and deflection of the electron beams in the two cathode ray tubes is.