Automatic gain control system for double-beamed spectorgraph

Claim 1

AN AUTOMATIC GAIN CONTROL SYSTEM FOR A DOUBLEBEAMED SPECTROGRAPH, SAID SPECTOGRAPH INCLUDING A SOURCE OF A REFERENCE POTENTIAL CONSISTING OF THE SERIES COMBINATION OF A RESISTOR AND POTENTIAL SOURCE SHUNTED BY A ZENER DIODE, A SOURCE OF A MEASURED POTENTIAL, A DIFFERENTIAL AMPLIFIER CONTROLLING A SERVOMOTOR, A FIRST LINEAR POTENTIOMETER TO COMPENSATE FOR POTENTIAL VARIATIONS ARISING FROM TRANSMISSIVITY CHANGES ARISING FROM A SPECIMEN WHEN EXAMINED IN SAID SPECTROGRAPH, SAID POTENTIOMETER HAVING A LINEAR RESISTANCE CHARACTERISTIC AND HAVING ONE FIXED TERMINAL CONNECTED TO THE SLIDING CONTACT OF A SECOND LINEAR POTENTIOMETER AND HAVING ONE GROUNDED FIXED TERMINAL, SAID FIRST POTENTIOMETER HAVING ITS SLIDE CONTACT CONNECTED TO AN INPUT CONNECTION OF SAID AMPLIFIER, SAID SECOND POTENTIOMETER HAVING A FIRST FIXED TERMINAL GROUNDED AND HAVING A SECOND FIXED TERMINAL CONNECTED VIA A RESISTOR TO SAID SOURCE OF A REFERENCE POTENTIAL, SAID DIFFERENTIAL AMPLIFIER HAVING ITS INPUT DERIVED FROM SAID REFERENCE POTENTIAL AND SAID MEASURED POTENTIAL, SAID CONTROL SYSTEM BEING CHARACTERIZED IN THAT THE OUTPUT OF SAID DIFFERENTIAL AMPLIFIER IS CONNECTED TO THE INPUT OF A PHASE-SENSITIVE RECTIFIER, THE OUTPUT OF SAID RECTIFIER IS CONNECTED TO AN R-C NETWORK, AND SAID R-C NETWORK IS ALSO CONNECTED BY MEANS OF A RESISTOR TO SAID SECOND FIXED TERMINAL OF SAID SECOND POTENTIOMETER.