Abstract: In a spectrophotometer having a cuvette, a photoelectric detector having a photosensitive surface, a light source arranged for passing a light beam through the cuvette onto the photosensitive surface, an imaging optical system arranged between the cuvette and the photosensitive surface or a rear image thereof being located in a focal plane of the optical system outside the image plane of the light source, whereby the light beam impinges on the photosensitive surface as a relatively large light spot of substantially uniform illumination and, as a result, the location and size of the light spot is not adversely affected by parallel offset, and the demands as to accuracy and alignment of the cuvette are reduced.

Abstract: A flowmeter for accurately determining the rate of flow of a gas substantially independent of its molecular composition and also for determining a measure of the velocity of sound in that gas. The gas flows through a transducer assembly. Disposed in the transducer are two cylindrical transducers each capable of producing or responding to acoustic compressions in the gas. The transducers are alternately switched between transmitting and receiving with one transducer at a given instant being used to transmit and the other to receive. The phase difference between the transmitted and the received signal for two successive transmit-receive cycles are stored with the difference between two successive stored phase differences indicating the magnitude and the direction of fluid flow and the sum of the stored phase differences providing a measurement of the velocity sound in that gas.

Abstract: The desired element in a specimen to be analyzed by atomic absorption spectroscopy is deposited in the spectroscope measuring tube in a concentrated form by first distilling away all components of the specimen that are more volatile than the element, then increasing the heat to distill off the desired element which is condensed on the cooler walls of the measuring tube while all components less volatile than the element will remain in the adjacent heated specimen crucible.

Abstract: A wide angle strip camera system which, in combination, includes a wide angle lens, having a curved conjugate focal surface, an image-receiving surface, a curved exposure slit disposed adjacent the image-receiving surface; the lens, image-receiving surface and exposure slit being so mounted that a semicircular strip at a constant preselected field angle in an object field is focused on the image-receiving surface. The system is fixedly supported in a vehicle, such as an aircraft, whereby the forward velocity of the vehicle provides image motion. The exposure slit is curved to correspond to field points of equal range so that there is negligible differential image motion within the slit, the slit being of such width in the direction of vehicle motion to result in uniform exposure; and the image-receiving surface is driven in the direction of vehicle movement at a speed corresponding to the altitude-velocity ratio of the vehicle with respect to the object field.

Abstract: An interferometer for rapidly measuring the phase profile and intensity distribution of a high powered continuous wave laser beam. The optical wave front to be measured is re-imaged on the surface of a rotating drum containing pairs of closely spaced apertures which rapidly scan the optical wave front and produce two radiation beams that interact to generate an interference fringe pattern in accordance with the principle of Young's two-slit interferometer. The interference pattern is focused on the surface of a high-speed optical chopper containing slits equal to half the width of each interference fringe pattern and the fringe radiation passing through the slits is detected by a transducer that generates an electrical sinusoidal output signal having a frequency corresponding to the chopper modulating frequency, but phase-shifted left or right by an amount corresponding to phase variations in the scanned wave front.

Abstract: Developed primarily as a selector for use with a system for analyzing gases from any one of sixteen remote positions, the valve includes a platen containing on one surface sixteen circumferentially aligned input ports and one central output port. Rotatable adjacent the opposite surface of the platen is a selector manifold having a conduit that connects the central output port with any one of the input ports. To rotate the manifold to a new position, a solenoid connected to the rotating shaft on the manifold lifts the manifold from the platen while simultaneously engaging a clutch on a continuously rotating motor shaft. When the selector manifold reaches the desired sample position, identified precisely by the position of a digital encoder disc, the solenoid is released and a spring disengages the motor clutch and forces the selector manifold to seal against the selected port in the platen.

Abstract: A wide angle strip camera system which, in combination, includes a wide angle lens, having a curved conjugate focal surface, a first image-receiving surface, a first curved exposure slit disposed adjacent the first image-receiving surface; the lens, first image-receiving surface and first exposure slit being so mounted that a first curved strip at a constant preselected field angle in an object field is focused on the first image-receiving surface; a second image-receiving surface; a second curved exposure slit disposed adjacent the second image-receiving surface; fold flat elements interposed between the lens and the second exposure slit; the lens, fold flat elements, second image-receiving surface, and second exposure slit being so mounted that a second curved strip at a second constant preselected field angle in the object field is focused on the second image-receiving surface.

Abstract: Disclosed is an apparatus and method for using same for atomic absorption determination of volatile, thermally decomposable compounds. The test sample is converted to a gaseous sample in a reaction vessel with an inert gas atmosphere. The gaseous sample in the inert gas is then introduced into a heatable measuring cell arranged in the ray path of an atomic absorption spectrometer. To further assist decomposition, the inert gas is heated prior to entering the measuring cell.

Abstract: The combustion of hydrogen at the open ends of an atomic absorption spectrometer heated atomizing tube that is being supplied with substances or reagents containing volatile hydrides is eliminated by tube extensions of low heat conductive material that lower the temperature of the gas below its flash point.

Abstract: A circuit for selecting a clipping level including a passive clipping element having a transfer function like that of either a zener diode, two series connected opposing zener diodes or other passive clipping elements. An inverting operational amplifier with a selectable gain couples to the passive clipping element and by adjusting the amplifier gain, the clipping level can be selectively reduced to almost zero from that of the clipping level for the passive clipping element itself.

Abstract: Method and apparatus for generating a gaseous test sample from a liquid sample and for transferring this test sample into a measuring cuvette of an atomic absorption spectrometer, in which an inert gas flow is directed through a sample vessel and into a measuring cuvette and, after the air has been displaced from the sample vessel, a reagent is added for generating a gaseous test sample, the test sample being carried into the measuring cuvette by the inert gas flow, wherein prior to the adding of the reagent, the flow rate of the inert gas flow is changed-over from a higher value to a lower value.

Abstract: A pair of optical beams of radiant energy from separate paths in a spectrophotometer are coaxially merged into a single composite beam with an optical member which resembles a coarse echelette grating. A reflective surface which includes the surfaces of sidewalls within a plurality of parallel grooves is disposed on the optical member. The grooves are arranged in a lateral array and are generally V-shaped cross-sectionally. The beams to be combined are directed upon the sidewalls and the composite beam is emitted therefrom in accordance with the law of reflection. When the beams to be combined include non-collimated rays, shadowing is provided by the portion of the optical member between adjoining sidewalls of adjacent grooves to reduce flare. Furthermore, image aberrations as caused by off-axis operation due to use of a spherical mirror in the beam combining arrangement, are substantially corrected by the optical member.

Abstract: A cross-talk balancing circuit for double-beam spectrophotometers is disclosed. The circuit includes means to measure in four successive sample periods the sample plus sample re-radiation (S + s), reference radiation plus reference re-radiation (R + r), sample re-radiation (s) and reference re-radiation (r). The detector, however, does not respond quickly so it introduces cross-talk into each measurement. Electronic phasing circuitry selects the time when the detector output is sampled so that the cross-talk in the measurements is equalized permitting it to be subtracted out of the measurement thereby leaving a remainder which accurately corresponds to the desired quantities S and R.

Abstract: A connector assembly including a plurality of male connector members each disposed for mating with a female connector member. Each female connector member is disposed on a support so that as the male and female connector members are urged together, electrical connection between all said pairs of male and female connector members does not occur simultaneously. Likewise as the connector members are urged apart, electrical connection is broken for some pairs of male and female connector members before others.

Abstract: In a plotting apparatus such as a spectrophotometer having a modifying system which introduces a phase lag between the occurrence of a change in a dependent variable quantity and plotting thereof against an independent variable quantity, in one embodiment, a cam is used to provide a quantity representing the dependent phase lag and the output of the cam is coupled to the driving system for the plotter so as to introduce therein a phase shift to compensate for the phase lag. In another, electrical embodiment the same object is accomplished by digitizing the phase lag and using the digital value to offset the wavenumber stepper motor and the chart stepper motor in the spectrophotometer with respect to each other.

Abstract: An apparatus for precisely polishing an optical surface is described. The apparatus includes polishing pads which are small in size in comparison with the surface being polished. The pads are maintained in contact with and moved across the surface being polished by a pad driver in a manner producing a removal profile which is maximum at the center of pad movement and minimum at the extremes of pad movement. A position drive means is utilized to move the pad drive along a substantially spiraling path centered at the center of the surface being polished and spiraling outward to the parimeter where parallel spiral arcs are spaced a constant distance apart along any given path radius. By controlling the speed of movement along the contour path, the rate of material removal at a particular position on the optical surface is controlled.

Abstract: A flexure, useful as a universal joint between two corotating members, the flexure being capable of flexing about two orthogonal axes, but providing extremely good stiffness with respect to translational forces is accomplished in a flexure in the form of a cross including two members having a cross-shaped cross-section extending along two mutually perpendicular axes, the members terminating at each end in solid pieces with the solid pieces at the end of the one member used for attachment to one of the rotating members and the solid pieces at the ends of the other member for attachment to the second rotating member.

Abstract: A pneumatic nebulizer of the type used for aspirating a fine spray of a liquid analytical sample into the sample burner flame of an atomic absorption spectrophotometer or the like. The nebulizer comprises an atomizing venturi nozzle formed of corrosion-resistant material, the nozzle including a monolithic flexible tube having one end extending to a sample source and its other end terminating coaxially within an apertured nozzle member to define therewith an annular orifice through which high velocity gas flow occurs to aspirate sample liquid from the other end of the tube.

Abstract: .Iadd.A rotary potentiometer with speed reduction gearing. A multi-tap closed loop distributed impedance is coupled by a mechanical configuration including a shaft to selected taps on an autotransformer. The mechanical coupling configuration permits the output from the wiper on the closed loop distributed impedance to change as a function of shaft position and to jump from one end of the autotransformer to the other while the shaft is continuously rotated in a given direction. .Iaddend.

Abstract: An atomic absorption spectrophotometer incorporating discrimination against "background" absorption, i.e., absorption not caused by the resonant line absorption by the element being measured. The device includes a resonant line emitting source (e.g., a hollow cathode lamp) and a continuous spectrum light source (e.g., a deuterium lamp), a monochromator and a detector system. The improvement comprises a specific chopper arrangement which sequentially causes: (a) the resonant line light from the hollow cathode lamp to go to the sample path, (b) this light to go to the reference path, (c) the continuous spectrum light from the deuterium lamp to go to the reference path, and finally (d) the continuous spectrum light to go to the sample path. By comparing the light intensities during intervals (c) and (d) the effect of the background absorption can be determined and compensated for so as to determine the relationship between (a) and (b) free of the effect of such background absorption.