Abstract: A filler apparatus for cryogenic dewars, such as are used in infrared detectors in infrared spectrometers, has an inlet port funnel which is connected to a liquid delivery tube which extends downwardly and into the liquid coolant containment vessel of the detector. A gas discharge tube extends co-axially with and spaced outwardly from the delivery tube and is connected to the fill port of the detector to direct gas resulting from evaporation of coolant within the detector up to a gas outlet funnel which is itself co-axial with and spaced outwardly from the inlet port funnel. A screen is mounted over the tops of the inlet and outlet funnels. The coolant, such as liquid nitrogen, is poured by the operator into the inlet funnel, which may be located at a position on the top surface of the cabinet of the spectrometer, and the operator can observe whether the detector is overfilled by noting whether the coolant liquid overflows into the gas discharge tube or up into the space between the inlet and outlet funnels.

Abstract: An analysis system accepts physiological sensor signals, including electroencephalogram (EEG) and other signals commonly sensed in sleep analysis, stores the raw data for later retrieval, extracts features from the digitized signal data which are of a type apt to be significant in classifying and detecting physiological functions (such as the state of sleep) and matches the extracted features to patterns which indicate the type of feature that has been extracted. The matched features are then utilized to classify for each epoch (limited period of time) the state of the physiological function (such as the stage of sleep) for that epoch. The results of the classification analysis are displayed on a CRT screen to the operator on a real time basis and in time correlation with representations of detected features from the various physiological signals.

Abstract: A gas sample collection device and method for cold trapping individual gas bands from a gas source that may include a chromatographic separation and for spectrographically analyzing the individual gas bands. The device includes a vacuum chamber containing a rotatably supported highly thermally conductive transmissive substrate having a highly thermally conductive support axle and at least one transmissive surface for holding a sample deposited thereon. A gas inlet is provided for depositing a mixture of sample and matrix material on the transmissive surface which is maintained at a sufficiently low temperature to cause solidification of the gas. A first set of optical elements directs an incident beam of electromagnetic analytical radiation from a source onto the solidified deposit, while a second set of optical elements directs the portion of incident beam transmitted through the deposit and substrate to a detector that is sensitive to the spectral wavelengths being investigated.

Abstract: A digital oscilloscope displays two waveforms on the CRT screen, a scroll bar waveform which is an abstracted representation of the full waveform data stored in memory and a generally expanded portion of the full waveform data in the memory. The portion of the full waveform that is displayed is selected by the operator by positioning cursor brackets along the abstracted scroll bar waveform to define a region of interest between the brackets. The region of interest so selected is displayed in expanded form showing all data points in the memory for the portion of the waveform being displayed. Creation of the abstracted scroll bar waveform is obtained by examining the waveform data in sections of equal time length and determining whether any data in each section falls within a series of predetermined ranges. The scroll bar waveform is formed of a series of columns of pixels equal in number to the number of sections of memory data, and having a number of pixels in each column equal to the number of data ranges.

Abstract: An interferometer modulator (10) has a housing (12) that encloses a moving mirror (14) attached to a mirror arm (18) which is suspended by links (34, 36) from the housing (12). The links (34, 36) are attached to the mirror arm (18) at swinging pivots (42, 44) and are attached to the housing (12) at fixed pivots (46, 48). One of the fixed pivots (46) is mounted within an adjustable block (68) the position of which may be adjusted by the turning of adjust screws (82, 76). Turning of one of the adjust screws (82) adjusts the distance between the fixed pivots (46, 48) to match the distance of the swinging pivots (42, 44), thus correcting for vertical tilt. Turning of the second of the adjust screws (76) compensates for any angular differences that would prevent the links (34, 36) from moving in the same plane of motion, thus correcting for horizontal tilt.

Abstract: An audiometer is provided with attenuators which have two successive stages, a main attenuator providing a large range of attenuation and a second stage which is capable of providing silent switching and finely adjustable attenuation. The signal from the main attenuator in the first stage is provided through two signal paths in the second stage to two input terminals of the earphone, with the sound output from the earphone determined by the voltage across the two input terminals. The first of the signal paths includes a pad having fixed attenuation which provides a low level voltage output signal to the one input terminal, and the other signal path includes an adjustable attenuator which provides fine adjustment of the magnitude of the output signal across the earphones.

Abstract: A circuit for automatically matching the gain and offset of a time-shifted digitizing channel in a data acquisition circuit which includes a reference digitizing channel, having a fixed voltage reference, and at least one time-shifted digitizing channel having components that are adjustable for gain and offset. Feedback is provided by examining the dynamic range and average value of a known input signal which is digitized, sent through the time-shifted digitizing channel and stored in memory. A microprocessor reads the stored data and, by separately varying the gain and offset parameters, computes optimal values for each parameter. Digital-to-analog converters (DAC's) allow the microprocessor to communicate with one fixed-gain variable-offset amplifier in the front end and with one fixed-gain variable-offset amplifier and one analog-to-digital converter (ADC) in each time-shifted digitizing channel.

Abstract: A twin-arm interferometer spectrometer having a tiltable reflector assembly, which includes a pair of mutually facing parallel reflective elements, varies the path length of both interferometer arms simultaneously to achieve high resolution in a small, low maintenance design. Collimated electromagnetic radiation is split by a beamsplitter into first and second arm beams. Both arm beams impinge on the tiltable reflector assembly, to retroreflectors, and back to the beamsplitter wherein they recombine to form an exit beam. The exit beam is directed to a sample and then to a suitable detector. Modulation of the exit beam is produced by tilting the reflector assembly about an axis parallel to the reflective elements in the reflector assembly. This tilting causes a simultaneous variation in the path length of both interferometer arms, and thereby yields a large total path difference with a relatively small movement.

Abstract: A thermogravimetric analysis flow cell interface unit has an elongated tubular cell body, glass inlet and outlet transfer lines integrally connected to the cell body for flowing a gas therethrough, a window element for allowing passage of an infrared radiation beam into and out of the cell body, and a mirror element for reflecting the radiation beam back through the cell body. The mirror element and the window element are assembled to the cell body in such a manner that the entire unit may be quickly disassembled and reassembled for easy cleaning and replacement. The flow cell assembly is adapted to interface a thermogravimetric analyzer and an infrared spectrometer.

Abstract: The ends of two composite superconductors (10a and 10b) having many filaments (12) are joined together to form a joint that is durable, superconducting under proper conditions, and has good shunting capacity. The filaments (12) are exposed by removal of the normal conducting matrices (14a and 14b) from the ends of the composite conductors (10a and 10b) to be joined. The superconductive filaments (12) from each of the composite conductors are inserted together into a sleeve (16) of bimetal construction. The inner surface (18) of the sleeve is made of superconducting material and is metallically bonded to the outer surface (20) of the sleeve which is made of normal conducting material. The bimetal sleeve (16) abuts the matrices (14a and 14b) of the composite conductors (10a and 10b) on one end, and the filaments (12) extend beyond the opposing end of the bimetal sleeve (16). The bimetal sleeve (16) is crimped to form a cold weld joint, and then severed in the region of the crimp to form another cold weld joint.

Abstract: A hearing aid system utilizing digital signal processing is programmable to fit the hearing deficit of a particular use and adaptive to the sound environment to maximize the intelligibility of the desired audio signal relative to noise. An analog signal picked from a microphone is amplified, filtered and converted to digital data. A digital signal processor preferably performs spectral shaping on the data to match the user's preference and performs a non-linear adaptive amplification function on the digital data. The amplification gain function may include several piecewise linear sections, including a first section providing expansion up to a first knee point, a second section providing linear amplification from the first knee point to a second knee point, and a third section providing compression for signals above the second knee to reduce the effort of over range signals and minimize loudness discomfort to the user.

Abstract: Gaseous ions trapped within an analyzer cell of an ion cyclotron resonance mass spectrometer are excited into resonance by a swept radio-frequency electric field having an envelope of trapezoidal shape. The envelope includes an onset region which ramps linearly from a zero level to a non-zero constant-amplitude level, a constant-amplitude region having the non-zero constant-amplitude level, and a termination region which ramps linearly from the constant-amplitude level to the zero level. The field has a generally constant-amplitude power spectrum and imparts relatively uniform energy to ions having natural cyclotron frequencies of interest.

Abstract: A video mixer circuit is used to combine two video signals, one of higher image quality than the other. The poorer of the two video signals is gated to clamp off its poorer signal during selected intervals of the video signal. The intervals of clamping off are determined by a discriminator sensitive to the voltage level of one of the video signals.

Abstract: The position of the moving mirror (20) in a Fourier-transform infrared spectrometer is monitored with a circuit which has an incremental counter formed of a plurality of cascaded up/down counters (82, 84, and 86) that count the pulses received by a laser detector (42) to yield a relative position count. A microprocessor (100) maintains an absolute position count by reading the counters (82, 84, and 86) and updating its absolute position count at regular intervals. A portion of the circuit is dedicated to discriminating the direction of the moving mirror (20) by gating circuitry connected to the digitized output of the laser detectors (42, 44).

Abstract: An interchangeable beam splitter holder includes a retainer which holds the beam splitter, and a front door and rear door which are both hingedly connected to the retainer. The doors are movable between a closed position, in which the doors substantially cover the beam splitter, and an open position, in which the doors are pivoted upwardly so that the beam splitter is exposed. The beam splitter holder also has three adjusting screws with ends which are adapted to abut against pivot points in the interferometer to thereby align the beam splitter. The beam splitter holder also has three spring plungers which abut against surfaces within the interferometer to push the ends of the adjusting screws against the three pivot points in the interferometer.

Abstract: An X-ray sensitive camera pick-up tube has an input end that has a circular glass surface that has areas of phosphor coating and of bare surface. The area of phosphor coating is a rectangle that fits within the circular glass surface and is limited to the area used for X-ray imaging of a specimen placed in front of the input end.

Abstract: A segment constituting several points of digitized waveform data from a digitizer is stored in a pixel memory which has a number of memory locations corresponding to the number of pixels in the horizontal screen width of a raster scan video screen. As each new data point is written into a sequentially higher location in the memory, the data at the memory location a selected number of memory locations lower, constituting the desired number of pixels in the waveform segment, is erased. When a full new segment of data is in the waveform memory, the contents of the memory is provided to a raster scan graphics control unit which causes a new raster scan frame to be written on the video monitor screen. Only the portion of the waveform corresponding to the segment of waveform data in the waveform memory is illuminated on the screen. New data continues to be written into the waveform memory until another full segment of waveform data is in the memory and all previous waveform data points have been erased.

Abstract: A mounting apparatus for mounting a microphonic probe tube on a patient includes a headband adapted to fit securely on the head of a patient and an adjusting arm which extends outwardly from the headband above each ear of the patient. Each adjusting arm is mounted to the headband in a manner which allows lateral adjustment of the position of the arm so that it can be located directly over the ear canal. The microphonic probe tube is mounted to a mounting rod extending downwardly from the adjusting arm and can be positioned at a point directly outwardly from the ear canal. When the probe tube is so positioned, a dial at the end of the adjusting arm can be turned by the operator to move the probe tube tip a selected distance into the ear canal of the patient to a position at which the real ear measurements are to be made.

Abstract: A probe tube is inserted into the ear canal of a patient to a first position in which the probe tube tip is spaced well away from the ear drum. A broad band sound signal is provided to the patient's ear and a frequency response of sound detected at the probe tube tip is taken. The probe tube tip is then moved a known distance to a second position within the ear canal, the broad band sound stimulus signal is again applied, and the frequency response of sound detected by the probe tube tip is taken. The distance of the probe tube tip from the ear drum can be determined from the two frequency responses, particularly by subtracting the frequency response in dB at one position from the frequency response in dB at the other position, and the difference frequency response will show a distinct peak at a quarter wavelength null frequency, which allows the distance of the probe tube tip from the ear drum to be estimated based on the relationship.

Abstract: A self-aligning fluid bearing for supporting a moving part, and allowing that part to move along at least one flat support surface substantially without friction, includes a body with at least one planar face having at least one spheroidal concave depression therein, channels within the body for directing pressurized fluid to each depression, and one planoconvex disk for each depression. Each disk includes a convex spheroidal surface with a spherical radius which is approximately equal to that of the corresponding concave depression and an oppositely facing planar surface so that the convex surface of the disk is located in spaced relation to the depression surface when pressurized fluid is directed into the depression.