Abstract: Disclosed is a fluorescence spectrometer having an intermittently activated sample irradiating source, such as a UV lamp, the periods of activation being short (e.g., 100 microseconds) in comparison to the intervening inactive periods (e.g., 20 milliseconds). Fluorescence radiation emitted by the sample is detected by a photomultiplier, the output signal of which is supplied to an integrating amplifier for utilization. A field effect transistor (FET) in the output circuit of the photomultiplier has its gate coupled to a control unit which determines the activation periods of the lamp and, in timed relation thereto, cuts off the FET to interrupt the output circuit during periods that the lamp is inactive. A dual channel fluorescence spectrometer is also described.

Abstract: An ozone absorbance controller for use with an ultraviolet light source, which includes a vented, trapped gas filter disposed in the optical emission path of said ultraviolet light source to absorb high energy ultraviolet rays of wavelengths below about 200 nanometers, and thereby substantially preventing the formation of ozone in the optical emission path subsequent to the filter.

Abstract: A circuit permitting an operator to accurately calibrate an instrument to indicate when a variable analog quantity being measured is zero. The analog signal is connected to the input of an operational amplifier which operates in stable mode for large analog inputs and operates in oscillation mode for very small analog inputs. The output of the operational amplifier is compared to zero and when the analog input is greater than zero, the comparator output is a logic zero. When the analog input is less than zero and not in the immediate vicinity of zero, the comparator output is a logic one. When the analog input is very small and less than zero, the operational amplifier operates in oscillation mode as the circuitry connected thereto causes it to oscillate with the duty cycle of the negative portion of the oscillation decreasing as the analog input comes closer to zero. Accordingly, the output of the comparator also oscillates.

Abstract: Sample preparation apparatus for forming a thin layer of diluted blood specimen on a substrate by centrifugal force includes a sample probe having coaxial blood and diluent conduits coupled to respective reversibly drivable peristaltic pumps having forward operation intakes connected to a diluent supply. A one-way clutch limits the diluent pump to forward operation and the pumps are geared to produce a blood-to-diluent displacement ratio of 2:1. A substrate holder is mounted on a carriage for selective insertion into and removal from a sealed centrifuge chamber in which it is spun at a high angular rate by a drive motor. Means are provided to form a curtain of flowing liquid within the chamber surrounding the spinning substrate to collect spun-off blood particles and aerosol. The liquid forming the curtain is drained by an exhaust pump which operates after spinning has ceased so as to create a partial vacuum for draining off residual aerosol prior to unsealing the centrifuge chamber.

Abstract: An electrodeless RF excited gas arc lamp for pumping a laser has a lamp envelope in the form of a loop having a continuous bore containing krypton, xenon or argon. Sufficient RF power to maintain a plasma in the gas in the loop is provided by a coil around its circumference so that it is linked by the flux generated by RF voltage through the coil. The laser rod to be pumped is mounted adjacent the loop. A diffuse reflector surrounds the lamp and laser rod to reflect back toward the rod light which does not impinge directly on the rod as well as any impinging light not initially absorbed by the rod.