Tracking accuracy control for analyzers

Claim 1

IN AN ANALYZER HAVING A LIGHT SOURCE, REFERENCE AND SAMPLE BEAM PATHS, A MONOCHROMATOR AND A WAVELENGTH SCANNING MECHANISM THEREFOR, AN ELECTRICAL SIGNAL GENERATOR, A PERIOD FILTER CIRCUIT, AND A SERVO FOR VARYING THE INTENSITY OF THE BEAM ALONG ONE OF THE PATHS, THE COMBINATION OF: A DRIVE MOTOR IN SAID WAVELENGTH SCANNING MECHANISM FOR CONTINUOUSLY VARYING THE WAVELENGTH OF SAID MONOCHROMATOR OUTPUT; A CONTROL CIRCUIT CONNECTED TO SAID DRIVE MOTOR FOR OPERATING SAID MOTOR AT A PREDETERMINED SPEED, SAID CONTROL CIRCUIT INCLUDING A FIRST RESISTANCE FOR SETTING SAID SPEED; A RESISTANCE-CAPACITANCE SECTION IN SAID PERIOD FILTER CIRCUIT BETWEEN SAID GENERATOR AND SERVO AND INCLUDING A SECOND RESISTANCE FOR SETTING THE TIME CONSTANT OF SAID FILTER CIRCUIT AND THEREBY CONTROLLING THE RESPONSE TIME OF THE SERVO; A LAMP; AMPLIFIER MEANS COUPLED TO SAID SIGNAL GENERATOR FOR ENERGIZING SAID LAMP AS A FUNCTION OF SAID SIGNAL GENERATOR OUTPUT; AND PHOTOSENSITIVE MEANS FOR CONNECTING IN CIRCUIT WITH EACH OF SAID RESISTANCES, WITH SAID PHOTOSENSITIVE MEANS POSITIONED FOR RADIATION BY SAID LAMP AND WITH THE RESISTANCE OF SAID MEANS VARYING AS A FUNCTION OF THE LIGHT IMPINGING THEREIN.