WIDE-RANGE RADIATION GAGE FOR DETERMINING DEVIATION OF A MATERIAL PROPERTY WITH A CONTROLLED-GAIN DETECTOR IN AN INTERRUPTABLE SELF-BALANCING MEASURING LOOP

摘要

Deviation of a gaged material property, such as material thickness, density, or weight-per-unit area, from a nominal value in a wide range of values is determined by a single-range, penetrative-beam type of radiation gage having an interruptable self-balancing measuring loop that includes a controlled-gain detector, thereby providing the radiation gage with a continuously variable gain characteristic. Any nominal value of material gaging property may be pre-established in a wide range of values by inserting digital material standards from a built-in magazine into the radiation beam, thereby causing the self-balancing loop to balance at a corresponding point in the variable sensitivity range. The presence of material to be gaged is detected before entering the radiation beam and interrupts and holds the self-balancing loop at the preset nominal value, while also removing the standards from the radiation beam. Subsequent measuring signals, together with a nominal value signal, are processed in a deviation gain adjusting circuit, whereby a linear deviation signal throughout the entire variable gain range is produced and fed to a deviation indicator.