Abstract: Apparatus for analysis of defects in polymerization reactor output, such as for gels in polyester polymer. The apparatus includes a tape forming unit, a tape analysis unit, and an image analysis computer. A sample of polymerization reactor output is converted to a tape form by compression between nip rolls and wound onto a reel. The tape reel is transferred to the tape analysis unit and the tape is threaded through an inspection zone to a takeup reel. A polyester tape is illuminated with ultraviolet light at the inspection zone and a camera captures images of gel fluorescence caused by the ultraviolet light. Interference filters are provided to attenuate background light. The signal generated by the camera is sent to an image analysis computer for determination of the total number of gels in preselected size ranges, the total area of the gels, and a defect ratio, which is defined as the total gel area divided by the area of the tape selected.