Density determining apparatus comprising radioactive source and detector

Claim 1

IN AN APPARATUS OF THE CLASS DESCRIBED, AN ENERGY RAY EMITTER ADAPTED TO BE PLACED IN DEFINITE CLOSE SPACE RELATIONSHIP TO A SURFACE AREA OF A TEST OBJECT TO PROJECT ENERGY RAYS INTO AND THROUGH THE TEST OBJECT, A COOPERATING ENERGY RAY DETECTOR ADAPTED TO BE PLACED IN DEFINITE CLOSE SPACE RELATIONSHIP TO ANOTHER SURFACE AREA OF THE TEST OBJECT TO DETECT EMITTED ENERGY RAYS THAT HAVE PASSED THROUGH THE TEST OBJECT WITH A NARROW FIELD OF PROJECTION, MEANS CONVERTING THE DETECTED INTERMITTENT ENERGY RAYS INTO ELECTRICAL IMPULSES, AN ELECTRICAL IMPULSE COUNTER, CIRCUIT MEANS FEEDING THE DETECTED ELECTRICAL IMPULSES TO SAID COUNTER, A TIMER CONTROLLING SAID CIRCUIT MEANS TO ESTABLISH TEST PERIODS OF PREDETERMINED DURATION, SAID ENERGY RAY EMITTER BEING OF A KIND WHEREFROM EMITTED RAYS ARE ALL OF THE SAME GENERAL ENERGY LEVEL AND ARE EMITTED AT THE SAME GENERAL RATE PER UNIT OF TIME THROUGHOUT TIMED TEST PERIODS ESTABLISHED BY THE TIMER, MEANS COMPRISING SAID IMPULSE COUNTER FOR CONVERTING IMPULSES COUNTED DURING A TIMED TEST PERIOD INTO A FIRST ELECTRICAL VOLTAGE OF A VALUE PROPORTIONAL TO THE NUMERICAL VALUE OF THE COUNTED ELECTRICAL IMPULSES AND WHICH FIRST VOLTAGE BEARS A DEFINITE RELATIONSHIP TO THE OVER-ALL DENSITY OF THE TEST OBJECT THROUGHOUT THE AREA THEREOF TRAVERSED BY THE DETECTED ENERGY RAYS, A PRIMARY CIRCUIT WHEREIN SAID FIRST VOLTAGE IS PRESENT, AN ELECTRICAL METER, A SECONDARY CIRCUIT WHEREIN A SECOND VOLTAGE IS PRESENT, MEANS FOR ADJUSTABLY CONTROLLING THE RELATIVE VALUES OF THE FIRST AND SECOND VOLTAGES TO THE END THAT THE FIRST AND SECOND VOLTAGES WILL BE APPROXIMATELY EQUAL FOR A SOUND TEST OBJECT AND THE VALUE OF THE FIRST VOLTAGE WILL EXCEED THAT OF THE SECOND VOLTAGE WHEN THE DETECTED RAYS ENCOUNTER DENSITY-REDUCING DEFECTIVE AREAS IN TEST OBJECTS, AND CIRCUIT MEANS FOR IMPRESSING UPON THE METER AND VOLTAGE PROPORTIONAL TO DIFFERENCES BETWEEN THE FIRST AND SECOND VOLTAGES, WHEREBY THE METER WILL PROVIDE A DIRECT READING INDICATION OF AND EXTENT OF DENSITY-REDUCING DEFECTS IN PORTIONS OF THE TEST OBJECTED TRAVERSED BY THE DETECTED RAYS.