Abstract: A laser inspection system is provided having an absolute closed loop dc system in which the power gain is automatically stabilized. In order to stabilize the power gain of the system and provide a closed loop absolute reference dc level, a sample of the radiation from the laser beam utilized to scan the material being inspected is applied to a photomultiplier tube for generating a reference pedestal signal which is dependent on the intensity of the laser beam and is free of the influence of the characteristics of the material being inspected. The reference pedestal signal is applied to a comparator which develops a control signal which is applied in a single closed feedback loop including in effect, the laser source and the light collection and detection system within the loop. This loop includes the photomultiplier tube and its high voltage power supply to which the control signal is applied for stabilizing the gain of the system.

Abstract: The beta ray gauge is augmented with a radiation inspection system for automatically improving products formed into a continuous web such as non-woven paper, non-woven textiles, plastics, etc. For example, the basis weight of a continuous web of paper is measured by passing the web through a beta ray gauge which generates a first signal based on the weight of the paper web. The first signal generated by the beta ray gauge is compared with a predetermined preset reference signal representing the basis weight desired. After the beta ray gauge measures the basis weight in the paper making process, a light inspection system applies a light source across the paper web and detects the light emanating therefrom to provide a second signal based on the characteristics of the paper web.

Abstract: A wide web laser scanner flaw detection method and apparatus are provided for rapid and accurate inspection of wide web materials. A plurality of laser sources are scanned by a plurality of aligned synchronized rotary scanners which repetitively scan the sources in sequence on a predetermined scan path over the material being examined with each laser scanning only a portion of the scan line. The rotary scanners are selectively blanked in sequence such that only one rotary scanner is scanning a single laser beam on only a portion of a line scan on the material in any given time interval and the blanking means are staggered such that one complete line scan is formed across the material by consecutive sequential alternating scans of each of the laser sources by each of the rotary scanners. The wide web is moved in a direction transversely with respect to the direction of the scan line for providing a raster type scan pattern along the wide web of material being inspected.

Abstract: A system for automatically calibrating and classifying measuring instruments such as mercury clinical thermometers, by accurately determining the distance between two reference points established by two known reference parameters. The detection of the reference points is made by scanning a laser beam over the mercury column and detecting the change in the reflection characteristic of the beam at the upper level of the column.