Spectrophotometer pulse amplitude ratio measuring means with feedback amplifier for noise and drift compensation

Claim 1

IN A SYSTEM FOR MEASURING THE AMPLITUDES OF SEPARATE PULSES, A DETECTOR FOR RECEIVING SAID PULSES AND CONVERTING THEM TO CORRESPONDING ELECTRICAL PULSES, AN AMPLIFIER HAVING AN INPUT AND AN OUTPUT, SAID INPUT BEING OPERATIVELY CONNECTED TO SAID DETECTOR FOR AMPLIFYING SAID ELECTRICAL PULSES TO PRODUCE CORRESPONDING OUTPUT PULSES, NOISE OCCURRING IN SAID AMPLIFIER SIMULTANEOUSLY WITH THE APPLICATION OF PULSES THERETO AND ALSO IN THE INTERVALS BETWEEN THE APPLICATION OF SUCH PULSES, A NEGATIVE FEEDBACK CIRCUIT CONNECTING SAID OUTPUT TO SAID INPUT, SAID FEEDBACK CIRCUIT INCLUDING MEANS FOR SAMPLING SAID NOISE AT SAID OUTPUT IN THE INTERVALS BETWEEN PULSES AND FOR APPLYING A D.C. BIAS TO SAID AMPLIFIER HAVING A MAGNITUDE CORRESPONDING TO THE AVERAGE AMPLITUDE OF COMPONENTS OF NOISE APPEARING AT THE OUTPUT DURING SAID INTERVALS TO REDUCE THE ZERO LEVEL AT SAID OUTPUT BY AN AMOUNT CORRESPONDING TO SAID AVERAGE AMPLITUDE, AND MEANS FOR MEASURING THE AVERAGE AMPLITUDE OF A SERIES OF SAID PULSES APPEARING IN SAID OUTPUT.