Abstract: There is a method and disclosed apparatus for detecting for the presence within a gaseous atmosphere of a gas of a concentration above a preset level. The detecting apparatus comprises a sensor including a heater/anode element and a collector/cathode element disposed to define a space therebetween through which the gaseous atmosphere flows. An actuable power supply is coupled to the heater/anode element and to the collector/cathode element for applying power thereto, whereby ionization of the gas causes a current flow through the collector/cathode element of a magnitude proportional to the concentration level of the gas in the gaseous atmosphere. An actuable alarm means provides an indication of the presence of the gas above the preset level. Detecting apparatus control operates the detecting apparatus in a monitoring mode, wherein the power supply is actuated and the alarm deactuated to detect and compare the current flow with the preset level.

Abstract: Characteristic values of transparent layers in the nanometer range, such a layer thickness and refractive index, can be determined with a spectro-ellipsometer. The task is to determine these values even with a less elaborate ellipsometer which only operates at one or a few wavelengths. In accordance with the invention, first at least one pair of the ellipsometric angles psi and delta are measured with at least one angle of incidence of the light beams on the sample for at least one ellipsometer wavelength, from which at least one characteristic value is determined for one ellipsometer period. Furthermore, the wavelength-dependent reflection of the probe in the wavelength range of interest is photometrically measured and from this the spectral dependency of the characteristic value is determined with the ellipsometrically measured characteristic value.

Abstract: In the atomic force microscopy method, the scanning system modified to provide high-frequency control is set into oscillation by electrical pulses having an amplitude that is adjustable and variable within a wide range. The pulses are so short that contact between the scanning tip and the sample is avoided. The pulse amplitude and/or form are varied in order to generate space charge zones in the semiconductor structures that are shaped differently within wide limits.

Abstract: There is disclosed a method and apparatus for repetitively taking samples of a predetermined quantity of a test gas in a liquid and introducing these samples to a test chamber. Each sample is agitated to release therefrom the test gas. The released gas is then conveyed to a sensor, which monitors the released gas for the presence of a concentration above the threshold level to produce an alarm indicative thereof. The samples of the test gas in a liquid may be repetitively taken from one zone of a plurality at a time until each zone is sampled. After one sample has been tested in the test chamber, it is discharged therefrom and the test chamber is flushed with a sample of the liquid and test gas taken from the next zone of the plurality before introducing the next sample from the same, next zone.

Abstract: A method for discovering amounts of halogen in a liquid is provided wherein the a reservoir comprising the liquid and suspected halogen is healed to a temperature characteristic of the solubility of halogen in the liquid to provide a vapor. After condensing, a sampling vapor is provided to from which the amount of halogen may be detected.

Abstract: Two embodiments of a molten metal gauging and control system using a fixed position capacitance sensor and methods therefor are disclosed. The first embodiment discloses a molten metal gauging system, the output of which can be used by various different external control systems to adjust the flow of molten metal appropriately. The second embodiment discloses a molten metal gauging and control system that comprises the molten metal gauging system of the first embodiment in conjunction with a tapered pin positioner system as the element to control the flow of molten metal.

Abstract: A position detection method and apparatus is disclosed which utilizes an electromagnetic probe as the control element in a relaxation oscillator circuit. The probe is energized by a pulse voltage waveform and the decay time of the induced transient probe voltage is utilized to modulate the frequency of the pulse generator. The probe transient voltage decay time is influenced by the proximity of an electrically conductive or magnetic object. Therefore, a frequency output is generated which indicates the position of the conductive or magnetic object.

Abstract: An improved oscillator circuit and method for measuring capacitance and small changes in capacitance is described. The circuit provides a digital output signal that has a frequency inversely proportional to the capacitance being measured, is substantially immune to stray capacitance, has low sensitivity to noise and temperature variations, is relatively simple and inexpensive to implement and provides a high precision measurement. One embodiment of the oscillator includes a capacitor to be measured, an integrator, an inverting amplifier, a comparator, a summing amplifier and a digital output circuit. A second embodiment of the oscillator further provides compensation for the non-linear response of a parallel plate capacitive transducer.

Abstract: An improved oscillator circuit and method for measuring capacitance and small changes in capacitance is described. The circuit provides a digital output signal that has a frequency inversely proportional to the capacitance being measured, is substantially immune to stray capacitance, has low sensitivity to noise and temperature variations, is relatively simple and inexpensive to implement and provides a high precision measurement. One embodiment of the oscillator includes a capacitor to be measured, an integrator, a comparator, a resistive attenuator, a summing amplifier and a digital output circuit. A second embodiment of the oscillator further provides compensation for the non-linear response of a parallel plate capacitive transducer.

Abstract: A method for discovering amounts of halogen in a liquid is provided wherein a reservoir comprising the liquid and suspected halogen is heated to a temperature characteristic of the solubility of halogen in the liquid to provide a vapor. After condensing, a sampling vapor is provided from which the amount of halogen may be detected.

Abstract: An apparatus for monitoring the concentration levels of halogen gas in a gaseous atmosphere as confined in an enclosure over a relatively extended period of time. Such monitoring apparatus includes a sensor including first and second electrodes disposed to define a space therebetween through which the gaseous atmosphere flows and a voltage source for applying a voltage between the first and second electrodes whereby an ionization current flows to the first electrode. A control mechanism illustratively in the form of a programmed microcontroller monitors the ionization current collected by the first electrode as the output signal of the sensor, to determine an increase therein as would be indicative of a halogen leak. Upon determining an increase of the sensor output signal above a predetermined difference, the control mechanism removes the energization from the halogen sensor whereby the ionization current is terminated and the life of the sensor extended.

Abstract: A single-use sensing device for a clinical chemistry analyzer system includes a carrier which supports a capillary passage. Species selective sensors are located within a test chamber portion of the capillary passage. A rotatable multichamber reservoir having a calibrant chamber for holding calibrant fluid and a sample chamber for containing a sample fluid is rotated first to a calibrant test position and then to a sample test position. In the calibrant test position, the calibrant chamber is connected to the inlet end of the capillary passage to draw calibrant fluid into the test chamber. In the sample test position, the sample chamber is connected to the inlet end to draw sample fluid into the test chamber and purge the calibrant fluid from the test chamber. A set of sensor readings are taken at each position, and concentration values are derived from the two sets of readings.

Abstract: An ion selective electrode includes a conductive electrode body which is supported by an insulating substrate. A convex dome-shaped membrane containing an electroactive species is deposited over and is directly in contact with the electrode body and a surface of the substrate surrounding the electrode body. The membrane has its greatest height above the electrode body and slopes down to meet the surface of the substrate. A moat formed in the insulating substrate surrounds the space from the electrode body to define the outer boundary of the dome-shaped member.