Abstract: Protected shall be an arrangement in which a liquid gas is evaporated within an insulated vessel below a hood, and in which the gas flows through a tube, which is within the hood, and penetrates through the bottom of the insulated vessel.

Abstract: Digital data acquisition apparatus for periodically sampling a waveform. Periodic data acquisition signals are provided at predetermined intervals with the waveform being sampled at the predetermined intervals in response to the data acquisition signals. The apparatus has at least a first operation mode wherein waveform sampling is initiated on the occurrence of a trigger event. In this operation mode, the apparatus includes an improvement for increasing its effective sample rate by providing a first data acquisition signal, following a trigger event, at an interval after the trigger event that is shorter than the interval between subsequent data acquisition signals. A second mode of operation may also be provided wherein sampling is manually initiated. In either operation mode, a phase locked loop may be employed to regulate, or tune, the interval between data acquisition signals.

Abstract: An inspection system for use in the fabrication of circuit boards of multiple, precisely registered layers. Each layer that is to be precisely registered within the circuit board is formed with at least two targets, each target corresponding in position to a target of another layer, and the targets of each layer defining a pattern that is unique to that layer. Radiography techniques allow a viewing of the registration of each target of a layer relative to a test target pattern. The test target pattern may be carried on a master template for the testing of individual layers for dimensional stability prior to stacking of the layers for lamination. Alternatively, the multiple layers may be stacked in their desired order, in which case the test target pattern for the targets of one layer are formed by the targets of at least two other layers.

Abstract: A graphic recording system wherein multiple recording elements are moved relative to a recording medium. The recording elements are selectively actuated for recording on the medium. A carriage supports the recording elements with the carriage and a recording element actuator being supported for movement relative to the recording medium and each other. During recording on the medium, the relative movement between the carriage and actuator is prevented.

Abstract: A photoplotter wherein a relative movement is produced between a photosensitive media and a radiant energy pattern generated on the media. The relative movement is in accordance with a desired exposure trace on the media. A difference between actual and desired relative movement is detected and the radiant energy pattern is varied to compensate for that difference. In a preferred embodiment, the radiant energy pattern is established by a pattern generator which displays an alterable pattern object on its face the position of the pattern object on the face being variable to compensate for the difference between actual and desired relative movement. The pattern object may be generated as a linear trace on a cathode ray tube (CRT) with the number of linear traces generated per unit of time being dependent on the relative movement velocity. The pattern images on the media resulting from the linear CRT traces or pattern objects overlap to provide a continuous exposure pattern along the desired exposure trace.

Abstract: In a cryostat of the type having nested vessels, a cryostat vessel wall spacing system wherein a plurality of rigid spacer stubs are secured between the vessel walls of adjacent vessels. The spacer stubs are mounted on the wall of an inner vessel to extend axially outwardly. A plurality of stub caps are secured to the adjacent vessel wall of a next outer vessel, with each stub cap having a recess designed to retain one of the spacer stubs therein. Each spacer stub engages its respective stub cap and is retained within the recess thereof when the walls of the nested vessels are at substantially the same temperature to uniformly and rigidly space apart the vessel walls of the nested vessels. When the vessel walls thermally contract because of the introduction of low temperature liquified gas into the inner vessel, each of the spacer stubs is withdrawn from its respective recess a distance sufficient to disengage said spacer stub and stub cap.

Abstract: A calibration circuit and method for instructing an instrument operator on how to adjust the brightness and contrast controls of a video display in order to achieve a precise display intensity directly proportional to the video drive signal input to the video display. A photometer detects the display intensity as the video drive is modulated and a differential amplifier compares the video drive to the photometer output signal thereby generating an analog offset signal highly representative of brightness and contrast offsets. The analog offset signal is converted to numerical offset values from which independent brightness and contrast offsets are computed. For raster-scanned video displays only a one-bit analog-to-digital converter, a comparator, is required and a multi-bit numerical value of the video offset may be obtained from the comparator output by the method of counting the number of scan lines in each frame giving a positive comparator output.

Abstract: A circuit which accepts a variable horizontal frequency input signal and an independent variable vertical frequency input signal and generates a combined video synchronization signal including horizontal synchronization pulses and serrated vertical synchronization pulses preceded and followed by equalization pulses in accordance with specifications established by the National Television Standards Committee. The circuit is useful for generating a combined video synchronization signal from the variable frequency horizontal and vertical synchronization pulses supplied by programmable cathode ray tube controller integrated circuits.

Abstract: A nuclear magnetic resonance technique that allows simultaneous temperature determination and spectral acquisition. The technique employs a modification of the lock circuit of a Varian XL-100 Spectrometer which permits accurate measurement of the difference in resonance frequency between a primary lock nucleus and another, secondary, nucleus. The field stabilization function of the main lock circuit is not compromised. A feedback signal having a frequency equal to the frequency difference is substituted for the normal power supply in the spectrometer's existing radio frequency transmitter to modulate that transmitter. Thus, the transmitter's radio frequency signal is enhanced in a frequency corresponding to the resonance peak of the secondary nucleus. Determination of the frequency difference allows the determination of temperature without interference with the observed spectrum. The feedback character of the circuit and the presence of noise make the circuit self-activating.

Abstract: Digital instrumentation for waveform measurement including method and apparatus for providing irregularly spaced sampling times to prevent misleading visual patterns of coordinate points due to the presence of signal frequencies above the Nyquist frequency. The method and apparatus includes means for plotting coordinate points having abscissa positions corrected according to actual irregular sampling times, method and apparatus whereby irregularities are repeated for each signal sweep, and method and apparatus utilizing a bit reversal system to achieve the irregularly spaced sampling times.