Abstract: In FT-DIRLD (Dynamic Infra Red Linear Dichroism) apparatus partly represented in FIG. 1, units 100-105, responding to interferometer output IB (indicated elsewhere), cause unit 106 to yield an interferogram combining static and dynamic dichroism interferograms. Reference signals respectively in phase and quadrature with cyclic sample strain are derived from rheometer 102. At each OPD point of predetermined uninterrupted scans, controller 108 routes simultaneously a data point of the combined interferogram and the reference signals to respective channels of multiplexer 107. A microprocessor (shown elsewhere) subsequently performs a best-fit-to-an ellipse sorting of the data and for each OPD derives: A) the value of the interferogram unaffected by sample modulation; B) the corresponding in phase term; and C) the corresponding in quadrature term; furthermore, from the A, B,C data-point series it generates the interferogram of each series and transforms it into a spectrum.

Abstract: The accuracy of the ratio between two time-varying quantities represented by electrical signals, such as the sample transmission (or absorption) signal and the reference signal in a double-beam, ratio-recording, infrared spectrophotometer, is impaired if the electrical signals are subject to inconstant phase shifts. The present invention counteracts the effect of phase shift variations, whatever their origin, by alternately reversing the order in which an elemental component of one quantity is made to occur with respect to an elemental component of the other quantity so that the said effect reverses in sign when the order is reversed and substantially cancels out when the respective elemental portions are combined to form the numerator and the denominator of the ratio. The invention is particularly described with reference to a spectrophotometer of the type referred to.

Abstract: The vitiating effect on the fluorescence measuring signal of extraneous currents flowing through the fluorescence detection means in flash spectrofluorimetry is almost completely eliminated by integrating the output of the fluorescence measuring means for the duration of the signal period, which includes a flash duration, and again for an equal period occurring between flashes which therefore does not include a flash duration. The second integral is then subtracted from the first to obtain a fluorescence measuring signal substantially unaffected by extraneous currents, such as dark current, sample phosphorescence, etc. The invention is applicable to single- and double-channel operation. In the latter, in addition to the fluorescence measuring channel there is provided a fluorescence reference channel. This enables the fluorescence measuring signal and the fluorescence reference signal to be ratioed together, the effect of extraneous currents having first been eliminated in both.

Abstract: The combination of an electrically conductive hollow body, a step-down transformer operable at a frequency greatly in excess of 1 kHz and solid phase temperature depressing means is used to realize the invention in its method and apparatus aspects. The temperature depressing means serve to bring the hollow body to a given depressed temperature so that when a gas component entrained in a gas carrier with which it forms mixture is passed through the hollow body for a period of, say, a few minutes the gas component condenses in the hollow body. The condensed component may later be freed and re-injected into the carrier by a process of thermal desorption which is achieved by direct ohmic heating of the hollow body via of the step-down transformer. The desorption time would typically extend over some ten seconds or so, as against the condensation time of several minutes, with the result that the gas component is concentrated in time, i.e.

Abstract: A column of particulate adsorbent is located within a longitudinally extending stainless steel tube. The pollutant gas to be monitored reaches the adsorbent by molecular diffusion after passing through a diffusion gauze at the diffusion end of the tube, a stagnant diffusion zone and a partition gauze forming one longitudinal boundary of the column. In one embodiment the diffusion gauze is removably mounted in a diffusion cap that may be slid over the tube; in another, the diffusion gauze and the partition gauze are mounted in a unit which in manufacture is fitted and permanently fixed within the tube. The invention establishes that the repeatability problem in molecular diffusion personal monitors lies in the hitherto unsuspected criticality of the stagnant diffusion zone parameters and provides a general solution enabling a good compromise between repeatability and sensitivity without the need for unduly close manufacturing tolerances.

Abstract: A spectrophotometric system includes an optical device for providing an optical path from a radiation generating means to a radiation receiving means. The optical device includes a substantially opaque layer which defines first and second coplanar face regions having different optical functions.

Abstract: In spectrophotometric apparatus in which there are a plurality of operating parameters a system for selecting predetermined combinations of operating parameters is provided, having as many user operable main mode selection stations as there are main modes in the design range of the system and having a mode multiplying system which is adapted to modify, in response to the operative state of user operable control means, each main mode selected out of at least some of the main modes in the range, for converting the selected main mode into an auxiliary mode.

Abstract: Repetitive-cycle object handling apparatus which includes, in combination, a feed station for accommodating a stack of slab-like objects of regular geometry, which are subjected to a feed force acting in the longitudinal direction thereof; a utilization station where objects fed seriatim from the feed station may be made to dwell before being moved on; a storage station for stacking one object at a time after the object has dwelled at the utilization station for a predetermined time interval; object transfer apparatus for sliding out a leading object from the stack at the feed station to the utilization station and, at the end of the predetermined time interval, to move the object on to the storage station; an object stacking ramp for guiding an object leaving the utilization station toward a stacking attitude at the storage station under the action of the object transfer apparatus; and preferably the apparatus further includes an object fulcrum disposed downstream of the object stacking ramp for enabling an

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: 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: Apparatus for controlling the width of an adjustable slit in response to the product of two variable functions, one of which is programmed, which includes at least one adjustable optical slit; slit width programming apparatus for producing a first displacement that is a logarithmic function of the instantaneous slit width conforming to a predetermined program; antilogarithm generating elements for producing a second displacement that is the antilogarithm of the first displacement; a phase adjusting mechanism for controlling the phasing between the first displacement and the second displacement; slit width selection apparatus operative on the phase adjusting mechanism for controlling the phasing in accordance with a given slit width selection; and actuating elements responsive to the second displacement and operative on the optical slit for controlling its width.

Abstract: A double-beam, time-sharing, ratio-recording spectrophotometer in which the reference signal data is evaluated both in an actual demodulation cycle and in a different cycle, which may be either a preceding or a following cycle. The two evaluations are combined to produce derived reference signal data. Ratioing means are included for extracting the ratio between the sample signal data evaluated in an actual demodulation cycle and the derived reference signal data. Predetermined multiplying factors may be used in arriving at the derived reference signal data. The interpolation of reference signal data from actual and non-actual demodulation cycles enables the effect of uncompensation on photometric accuracy to be minimized. Uncompensation results from the fact that in a time-sharing spectrophotometer sample and reference signal data do not occur at the same time and do not therefore relate to the same environment and the same wavelength.

Abstract: In a device such as a spectrophotometer with an associated chart recorder in which the speed ratio between a first displaceable member and a second displaceable member may be selectively changed within a predetermined range of speed ratios, in a first embodiment of invention which is mechanical in nature, a number of gear trains in constant mesh with each other are provided to obtain the different speed ratios. Each of the gear trains has associated therewith a rotary disc with circumferentially even spaced apertures, the gear train obtaining an input from the first displaceable member by means of arms rotatable concentric with the discs, the arms carrying a pin adapted to enter into positive engagement with any one aperture, the number apertures depending on the scale served by the associated gear train.

Abstract: An anti-smudge bar for a recorder is disclosed wherein the recorder has a drive means for advancing a strip chart in a longitudinal direction. The strip chart, as it advances, passes over a platen disposed upstream of the advancing means. A pressure roller adjacent the upstream side of the platen presses the strip against the platen. The pressure roller has a plurality of longitudinal grooves spaced by sharp crests which contact the chart in a manner preventing smudging of wet ink traces previously recorded on the chart. The ink traces are recorded on the chart by a recording pen which is movable in a direction transverse to the direction of chart movement. The roller and the pen are lifted from chart contact whenever the chart direction is reversed to permit subsequent recording on a chart segment previously recorded on.

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 optical system for measuring relative lateral displacement or velocity relative to a surface above which the system is independently supported has a grating consisting of different bands that are adapted to impart to incident light received from the surface two different optically selective characteristics such as different polarizations or different wavelengths. Light transmitted by or reflected from the bands is focussed through filtering means onto photodetectors which produce signals proportional to the light received thereby. The filtering means (polarization selective or wavelength selective, as the case may be) associated with the respective photodetectors respectively separate light coming from bands having one of said characteristics from light from the bands having the other of said characteristics.

Abstract: A correction system is disclosed for double-beam spectrophotometers of the optical nulling type in which a mechanical radiation attenuator is positionally adjusted in the path of the reference beam by means of an error signal proportional to the detected difference in intensity and between the sample and reference beams. The attenuator takes the form of a circular sector mounted for angular displacement about an axis through the sector circle center by a servomotor in response to the error signal. The sector contains one or more wedge-shaped apertures arcuately disposed about said center so that the reference beam passes through the apertures and is partially (or totally) occluded in accordance with the angular position of the sector.