Abstract: A circuit tester and test technique are presented that compresses the amount of data stored in local test data RAMs for the implementation of a circuit test, thereby reducing the amount of data that must be downloaded to the local test data RAMs, thereby improving test throughput. Derivative data vectors are utilized in addition to raw data vectors as part of the data compression technique. Further compression results from storing only unique data vectors in the local test data RAMs and utilizing a sequencer to control the order in which the unique data vectors are utilized. The sequencer includes test program logic and logic capable of implementing on test pins indirect counters.

Abstract: A method and apparatus are disclosed for reducing the likelihood of damage to digital logic devices under test or located in close electrical proximity to the device under test while attempting to locate faults in circuit assemblies using digital incircuit test techniques.

Abstract: A binary scaled current source in which a set of binary switches M.sub.1, . . . , M.sub.n controllably switch a current I to a selected one of a set of n outputs. Each switch M.sub.k is controlled by an associated control signal B.sub.k having a duty cycle of 2.sup.k-n-1. At any given time one and only one of the control signals is high so that the current I is diverted to the kth output a fraction 2.sup.k-n-1 of the time. In two particular schemes referred to as the weighted pulse width (WPW) and the weighted repetition rate (WRR) schemes, all of the control signals are periodic with a group pattern repetition period T. In the WPW scheme, B.sub.k has in each period T a single pulse of duration 2.sup.k-n-1 *T. In the WRR scheme, B.sub.k has in each period T2.sup.k-1 pulses each of duration 2.sup.-n *T. The output of each binary switch is typically passed through a low pass filter which conducts substantially only the dc component of the output current from the binary switch to which it is connected.

Abstract: A method of selecting values for parameters in a calibration map used to correct for measurement errors. The locations of points in a grid on an uncalibrated calibration plate are measured for different orientations of the calibration plate. The parameters in the calibration map and the parameters relating the orientations of the calibration plate are determined to minimize the deviation from congruence of the image under the calibration map of the grid in each orientation. The orientations should be related by rigid motions having rotation axes that are separated sufficiently to remove uncertainties in the calibration which arise if the rotation axes are all collinear or nearly collinear.

Abstract: A pulsed current source in which the dc component of the pulsed current is independent of variations in the duty cycle of the current pulses. A dc current source supplies a current I through a switch that alternately switches the current between a first output and a second output to produce at the first output the pulsed current I.sub.p. The dc component of the current at the second output is added to the current I, thereby making the dc component of the pulsed current insensitive to the duty cycle. In systems in which additional processing produces from I.sub.p a set of currents, the dc component of the sum of a first subset of these currents is made to equal I by adding to the input of the switch the dc component of the sum of those currents in the complement of the first subset.

Abstract: A nozzle plate for impulsive jet devices is proposed where the quality of ejected droplets is improved by means of additional non-emitting orifices. These orifices may act as fluid accumulators and tuned or untuned absorbers of pressure disturbances to optimize drop quality and reduce fluidic crosstalk between adjacent drop generators. The presence of these orifices permits additional degrees-of-freedom in the design of high-quality impulsive jet devices. Sufficient crosstalk reduction results that crosstalk reduction barriers can be eliminated.

Abstract: An ink jet drop generator is presented which has a nozzle plate containing at least one nozzle for controlled ejection of droplets of ink. The ejection of ink can be produced by a number of means including by production of a gas bubble in the ink in the vicinity of the nozzle. The nozzle plate also contains at least one drain hole to remove drops of ink from the outer surface of the nozzle plate. These drain holes are preferably connected to an accumulator having a pressure below ambient pressure to help draw drops of ink from the outer surface. The nozzle plate also contains isolator holes which are connected to a refill plenum to help dissipate disturbance energy in the ink to reduce fluidic crosstalk between emitters in multi-emitter heads.

Abstract: A technique is presented for producing tapered walls. In accordance with the disclosed technique, a mask is generated on a workpiece and the workpiece is etched through the mask to replicate the mask pattern into the mask. These steps result in walls at the boundaries of the replicated mask features. In many such processes, these walls are either substantially vertical or have an overhanging portion of the walls. In order to taper the walls, the upper corners of the walls are cut away to remove the overhang or to cut the corner back an additional amount to produce a controlled amount of taper.

Abstract: A coating is applied to an optical fiber to form a thin hermetic seal. The coating is preferably applied on-line by a process such as chemical vapor deposition. The coating retains its integrity under extreme conditions of temperature and pressure thereby expanding the range of uses of optical fibers.

Abstract: In accordance with the illustrated preferred embodiment, a system and technique are presented which enable several independent software tasks, referred to as partitions, to be stored in memory and concurrently utilized without interfering with each other's operation. This system and technique also enable physical memory to be dynamically mapped so that various dynamic structures, including partitions, can be dynamically allocated memory as needed without interfering with each other. Some interaction between partitions is also made available so that results generated by operation of one of the partitions can be utilized by other of the partitions.

Abstract: A method of making an electron permeable window is provided which entails depositing a thin film of an inert, high strength material or compound having a low atomic number onto a substrate by chemical vapor deposition (CVD). Following that deposition, a window pattern and window support perimeter are photolithographically defined and the substrate is etched to leave the desired window structure. For a particular class of materials including SiC, BN, B.sub.4 C, Si.sub.3 N.sub.4, and Al.sub.4 C.sub.3, films are provided which are exceedingly tough and pinhole free, and which exhibit nearly zero internal stress. Furthermore, due to their extreme strength, these materials allow fabrication of extremely thin windows. In addition, because of their low atomic number and density, they have excellent electron penetration characteristics at low beam voltages (15 to 30kV), so that most conventional CRT deflection schemes can be used to direct the beam.

Abstract: A spectrophotometer optical section is presented which employs a fine positioning beam director which corrects for any deflections of the output beam path and accurately positions the optical beam on the detector slit of the spectrograph. The detector slit is chosen to have a size slightly smaller than the size of the optical beam at the detector slit to have high slit throughput without introducing spurious absorption. The sample cells need not be rigidly mounted thereby enabling use of a sample cell and cell holder which allows quick, easy interchange of cells.

Abstract: A method of making an electron permeable window is provided which entails depositing a thin film of an inert, high strength material or compound having a low atomic number onto a substrate by chemical vapor deposition (CVD). Following that deposition, a window pattern and window support perimeter are photolithographically defined and the substrate is etched to leave the desired window structure. For a particular class of materials including SiC, BN, B.sub.4 C, Si.sub.3 N.sub.4, and Al.sub.4 C.sub.3, films are provided which are exceedingly tough and pinhole free, and which exhibit nearly zero internal stress. Furthermore, due to their extreme strength, these materials allow fabrication of extremely thin windows. In addition, because of their low atomic number and density, they have excellent electron penetration characteristics at low beam voltages (15 to 30 kV), so that most conventional CRT deflection schemes can be used to direct the beam.

Abstract: In electron beam lithography, a beam of incident electrons exposes a preselected circuit pattern in a thin resist layer deposited on top of a substrate to be etched. Some of the electrons scatter from the substrate back into the resist layer producing an undesired exposure which produces variable resolution of features. In accordance with the disclosed technique, the region of the resist which is complementary to the desired circuit pattern is also exposed by an electron beam which has been adjusted to produce an exposure approximating that due to backscattering. This additional exposure removes the spatial variability in resolution attainable by the electron beam lithography.

Abstract: An instrument is disclosed which performs measurements and calculates the average and the variance of the measurements. The particular instrument illustrating the invention is a spectrophotometer which measures sets of dark, reference and sample spectra for use in calculating an average absorbance spectrum and its variance. The measurements are performed in an order which enables the cancellation of measurement variation due to variation in instrument response. The order of measurements is determined by measurement subroutines which can be aggregated to produce a series of measurements performed over a user selected period of integration time.

Abstract: A new type of thermal ink jet print head is provided which is driven by an electron beam. The print head is constructed of an electron permeable thin film (electron window) which in one embodiment, has on one of its surfaces a plurality of electron absorbing (heater) pads that are in thermal contact with an ink reservoir. As electrons from a CRT traverse the thin film and are absorbed by a pad, they introduce an extremely large and rapid temperature increase in the pad. As a result, a sufficient amount of thermal energy is absorbed by the ink to cause a vapor explosion within the ink, thereby ejecting ink droplets from a nearby orifice in the ink reservoir. In another embodiment, the electrons traverse the window and are absorbed in the ink rather than in pads, and in another embodiment the electrons are absorbed directly in the window itself.

Abstract: An asynchronous interface enables the transfer of information between a set of devices operating in a loop and having a wide range of operating speeds. Each device can enter a Controller active state in which it sources command frames to control the loop operation. Each device can also enter a Talker active state in which it sources Data frames on a Listener active state in which it received Data frames. The transfer of frames is coordinated by a set of handshakes which enable the frames to be transferred in an asynchronous manner.

Abstract: A method and apparatus are disclosed for optically pumping the atoms of an atomic beam into a single trap state. An atomic beam is produced and is passed through a region of weak magnetic field to produce a magnetic splitting of energy levels. The beam is illuminated with a laser beam to produce selected excitations. The spectral distribution of the laser light is selected (1) to excite the atoms of the atomic beam to excited levels from which the atoms can decay into the trap state and (2) to avoid exciting atoms out of the trap state. Particular applications of the method and apparatus are described for atomic or ionic clocks and masers.

Abstract: A bit cell is presented which can provide a small weighted current without loss of switching speed. The bit cell contains a switch which is responsive to an applied control signal to direct the weighted current to an output or to divert it away from the output. Supplementary currents are supplied to the switch to provide sufficient current to the switch to charge and discharge parasitic capacitances of the switch within the switching time of the control voltage. The supplementary currents maximize switching speed at a given power dissipation and produce a constant offset current at the switch output. A D/A converter is presented which utilizes a plurality of such bit cells to maximize the speed of D/A conversion. The offset currents are eliminated from the converter output so that the output current is proportional to the digital input.

Abstract: A circuit for converting a triangular waveform into a sinusoidal waveform using the non-linear transfer characteristic of a first transistor differential amplifier. Second and third differential amplifiers are parallel-connected to said first differential amplifier with the slopes of their transfer characteristics in opposite sense thereto and having their operating points shifted on their transfer characteristics in opposite directions with regard to each other and symmetrically to the operation point of said first differential amplifier so that the resulting overall transfer characteristic of said first, second and third differential amplifiers has zero slope at the extremal amplitudes of said triangular waveform.