Positive type infrared analyzer

Claim 1

IN A POSITIVE TYPE INFRARED ANALYZER, THE COMBINATION OF: A RADIANT ENERGY SOURCE; AN OSCILLATOR; MEANS INTERCONNECTING SAID SOURCE AND SAID OSCILLATOR FOR ENERGIZING SAID SOURCE AS A FUNCTION OF THE OUTPUT OF SAID OSCILLATOR; A SAMPLE CELL AND FIRST AND SECOND DETECTOR CELLS MOUNTED IN OPTICAL SERIES FOR RECEIVING RADIATION FROM SAID SOURCE, EACH OF SAID DETECTOR CELLS HAVING A CAPACITOR THEREIN; A FLOATING D.C. VOLTAGE SOURCE CONNECTED BETWEEN THE CAPACITOR OF SAID FIRST DETECTOR CELL AND THE CAPACITOR OF SAID SECOND DETECTOR CELL FOR PROVIDING POLARIZING VOLTAGES ON SAID CAPACITORS, WITH EACH CAPACITOR BEING VARIABLE AS A FUNCTION OF THE ENERGY ABSORBED IN THE CORRESPONDING CELL FOR PRODUCING FIRST AND SECOND SSIGNALS; MEANS FRO COMBINING SAID SIGNALS TO PRODUCE A RESULTANT SIGNAL WHICH VARIES AS A FUNCTION OF AN UNKNOWN SUBSTANCE IN THE SAMPLE CELL; AN AMPLIFIER FOR RECEIVING AND AMPLIFYING SAID RESULTANT SIGNAL; A SYNCHRONOUS DETECTOR HAVING THE AMPLIFIED RESULTANT SIGNAL AND THE OUTPUT OF SAID OSCILLATOR AS INPUTS AND PRODUCING AN OUTPUT WHICH IS A FUNCTION OF SAID RESULTANT SIGNAL; A FILTER FOR SAID SYNCHRONOUS DETECTOR OUTPUT, WITH THE FILTERED OUTPUT BEING A MEASURE OF THE UNKNOWN SUBSTANCE IN THE SAMPLE CELL; AND MEANS FRO CONNECTING SAID FILTERED OUTPUT TO SAID CAPACITORS AND TO SAID D.C. VOLTAGE SOURCE FOR CONTROLLING THE POLARIZING VOLTAGES ON SAID CAPACITORS TO CAUSE SAID RESULTANT SIGNAL TO APPROACH ZERO.