1. A device for monitoring a fluid sample comprising: a. a compartmentalized housing including compartments for a sample signal electronic processing circuit including an alarm means and sample concentration indicating meter and an infrared source, a sampling chamber, a detector means and optics package, and a power supply, said sampling chamber including an intake means for continuously drawing a fluid sample into the chamber and an exhaust means for continuously exhausting the fluid sample from the chamber; b. an infrared source mounted in the electronic processing circuit compartment of said housing, said infrared source being shielded from the electronic processing circuit; c. a multipass mirror system mounted in the sampling chamber of said housing in the path of electromagnetic energy emanating from the source to form an optical path of selected length through an optics package to a detector, said selected length of the optical path providing increased absorption of the electromagnetic energy; d. an optics package mounted in said detector means and optics package compartment of said housing, said optics package including a rotatable filter/chopper wheel and means for rotating the filter/chopper wheel, said filter/chopper wheel including a plurality of filters operative in the infrared frequency range, a plurality of filters operative in the visible frequency range, and a reference filter, said plurality of filters equally spaced one from the other and from the center of the wheel and mounted in apertures prOvided therefor in the wheel, the portion of said wheel between filters forming a base line sampling area, said plurality of filters having diameters such that the aperture of energy impinging thereon is approximately one-third the diameter of the filter whereby sampling is at the top of a square wave or spike-flat top control signal with those filters operative in the infrared frequency range having half intensity widths of 1.5 micron, and those operative in the visible frequency range having half intensity widths + OR - 15A about the strong absorption wavelengths for component filters and the nonabsorbing region of the reference filter, a plurality of start and stop apertures formed in the filter/chopper wheel some adjacent the wheel periphery and some adjacent the wheel center, said apertures adjacent the wheel periphery being positioned in pairs between each filter to provide timing signals for base line sampling prior to sampling the following filter and said apertures adjacent the wheel''s center being positioned in pairs in relation to each filter to provide start and stop signals for sampling the filters and a synchronization aperture for resetting the control electronics each revolution of the filter/chopper wheel, and a bifurcated yoke means through which the filter/chopper wheel extends, said yoke means including in one bifurcation light sources and in the second bifurcation light detector means operative in response to light passing through the filter/chopper wheel apertures to produce electrical signals for operational control; e. a detector means mounted in the detector/optics compartment of the housing in the optical path for the infrared energy, said detector means including a beamsplitter for reflecting visible light to a first detector and transmitting infrared energy to a second detector, said detectors operative to produce electrical signals responsive, respectively, to received light and infrared energy; f. an electronic signal processing circuit mounted in the electronic signal processing circuit compartment of the housing comprising a plurality of sample and hold circuits and a control unit including a multiplexer, said plurality of sample and hold circuits operative responsive to the multiplexer control signals of the control unit to sample the detector outputs for each of the filter outputs, a plurality of difference amplifiers selectively coupled to the outputs of the sample and hold circuits for differencing between sample signals and reference signals to produce signals representative of the samples concentrations; threshold and detection channel circuits having inputs coupled to the difference amplifiers, and monitoring means including an alarm coupled to the channel outputs for selectively monitoring the sample concentrations; and g. a power supply mounted on the power supply compartment electrically coupled to power the electrical components and circuits including the infrared source, sampling chamber intake and exhaust means, and the electronic signal processing circuit.
