Abstract: Apparatus for measuring the concentration of a gas present in a sample chamber by ambient pressure diffusion employs a nondispersive infrared gas analysis technique. The sample chamber has the form of a tube that is closed at one end, with a source of radiation and a detector mounted side by side at the other end. The inwardly-facing surfaces of the tube are specularly reflective, whereby the optical length of the sample chamber is twice its physical length. A gas filter cell located in the optical path permits the concentration of an analyte gas to be measured accurately despite the presence in the sample chamber of an interfering gas. A small ultrasonic vibrator affixed to the wall of the sample chamber prevents unwanted particles from accumulating on the semipermeable membranes through which ambient gases diffuse into and out of the sample chamber.

Abstract: A replaceable wiper cartridge is described which is held captive within a shuttling scraper of a type known in the art which is pushed axially through a cylindrical reaction chamber intermittently to remove reaction products from the inside surface of the reaction chamber and from the outside surface of a smaller coaxial tube that extends the length of the reaction chamber. The replaceable wiper cartridge has an annular shape that is obliquely cut to permit a slight radial expansion to accommodate the smaller coaxial tube and to engage it in a tight sliding grip so as to scrape from the smaller tube any deposits.

Abstract: A snag-resistant wholly recoverable sinker for the distal end of a fishing line includes a bag into which a plurality of beads strung on a line are placed, the end of the line being attached to the lip of the bag, and the mouth of the bag being elastically constricted by a resilient collar. The diameter of the first bead at the proximal end of the string of beads is greater than the diameter of any of the remaining beads. When the bag becomes snagged, the fisherman has only to pull hard enough on the line to draw the larger first bead through the mouth of the bag against the resistance of the resilient collar after which the smaller beads follow thereby reducing the size of the bag until it is freed. In an extreme case, all the beads will be pulled from the bag, and they will be followed by the empty bag to which the distal end of the line is attached. Significantly, no parts of the sinker are lost in the process of freeing it, and the sinker may be reeled in and reassembled by the fisherman for reuse.

Abstract: Apparatus for simultaneously receiving a plurality of AM signals of widely differing strengths on a set of carrier frequencies and for re-broadcasting the AM signals at equalized strengths at either the original carrier frequencies or at a set of carrier frequencies that are offset from the original from the received frequencies by a constant difference. Regardless of whether the re-broadcast carriers are offset, the system includes provision for interrupting the re-broadcast signals by an audio message of general interest or public safety.

Abstract: Circuitry for simultaneously generating a set of carriers having preselected frequencies in the amplitude modulation broadcast band includes a circuit for producing a train of pulses having a crystal-controlled pulse repetition frequency equal to the separation in frequency between successive assignable frequencies in the broadcast band, each pulse in the train having a pulsewidth approximately equal to the reciprocal of the frequency of the lower end of the broadcast band and having a rise time approximately equal to the reciprocal of the frequency of the upper end of the broadcast band, so that the spectrum of the train of pulses includes components having frequencies equal to all of the assignable frequencies in the broadcast band, the pulse train being applied to a set of phase-locked oscillators connected in parallel, each oscillator being tuned to a different one of the selected components of the train of pulses.

Abstract: Apparatus and a method for generating all of the assignable carrier frequencies in the FM broadcast band and for frequency modulating the generated carriers includes a generator of a train of pulses having a crystal-controlled repetition frequency and a specific pulse shape which together produce a spectrum of odd harmonics of the pulse repetition frequency whose separation in frequency is identical to that of the assignable carrier frequencies. This pulse train is then mixed with a 98.0 MHz sine wave to translate the spectrum to the FM band. Simultaneous modulation of all the carriers is achieved by frequency modulating the 98.0 MHz sine wave, whereby the same modulation is imparted simultaneously to all of the carriers.

Abstract: The sensitivity of a nondispersive infrared gas analyzer increases with increasing pathlength, which increases the absorption of the infrared radiation by the gas whose concentration is to be determined. The present invention includes the addition of an obstructing element that further increases the average pathlength. In one embodiment the obstructing element consists of a highly reflective elongated cylinder located with its axis collinear with the axis of the tubular chamber. In another embodiment, the sample chamber includes a converging section, the smaller end of which is joined to an elongated tubular section of uniform cross section. The improvements are applicable to both pumped and diffusion-type sample chambers.

Abstract: A snap-on plastic lid for a bucket includes a fixed portion engaged to a lip on the rim of the bucket and pivotally connected by a living hinge to a movable portion that can be moved from a closed position to an open position. A toggle mechanism couples the movable portion to the fixed portion in such a way that the movable portion will remain in either the open position or the closed position until a deliberate force is applied to overcome the detenting action of the toggle. The entire lid can be molded as a unitary article if desired. In one alternative embodiment a positive mechanical lock is provided to secure the movable portion of lid in the open position, and in another embodiment bosses that extend above the lid facilitate stacking of buckets on which the lid is used.

Abstract: The apparatus is used to remove material uniformly from all regions of a wafer surface that is being polished. This is in contrast to conventional lapping machines which preferentially remove material from the high spots on the surface being polished so as to render the surface planar. The result of the present invention is achieved by providing a downwardly-opening plenum on the underside of a carrier. The opening is covered by a flexible membrane, and when a pressurized fluid is applied to the plenum, the membrane applies a uniform downward pressure across the entire upper surface of a wafer that is being polished. The uniform pressure results in a uniform removal of material all across the wafer. The wafer is typically 680 microns thick and the coating is typically two microns thick. Through use of the apparatus, the thickness of the coating is uniformly reduced to about 0.8 micron while maintaining the uniformity of the coating to within 0.02 micron.

Abstract: A method for simultaneously imposing a single modulating signal on a number of constant frequency carriers includes applying the single modulating signal and all of the carriers to a doubly-balanced mixer circuit that produces sideband signals that are uncontaminated by the carriers. The sideband signals thus produced are then combined with signals proportional to the carriers in a linear circuit to obtain an output signal equivalent to a signal that would result from combining separately modulated carriers.

Abstract: An apparatus for acquiring, holding, and releasing a wafer includes a soft resilient membrane that covers a horizontal backing plate. The lower face of the backing plate includes a number of recessed areas to which a vacuum can selectively be applied. To acquire a wafer, the wafer is elevated carefully until the upper side of the wafer contacts the lower side of the membrane. Next, a vacuum is applied to the recessed areas which sucks the resilient membrane into the recessed areas so that each recessed area becomes a suction cup that draws the wafer against the membrane. When the vacuum is replaced by ambient pressure, the resiliency of the membrane restores it to its original taut condition thereby releasing the wafer. The same apparatus can be used for uniformly polishing the lower face of the wafer by applying a pressurized fluid to the recessed areas during polishing, which causes the membrane to exert a uniform downward pressure on the wafer.

Abstract: The sensitivity of a nondispersive infrared gas analyzer increases with increasing pathlength, which increases the absorption of the infrared radiation by the gas whose concentration is to be determined. The present invention includes the addition of an obstructing element that further increases the average pathlength. In one embodiment the obstructing element consists of a highly reflective elongated cylinder located with its axis collinear with the axis of the tubular chamber. In another embodiment, the sample chamber includes a converging section, the smaller end of which is joined to an elongated tubular section of uniform cross section. The improvements are applicable to both pumped and diffusion-type sample chambers.

Abstract: An oxidation chamber used for irradiating an incoming liquid containing unwanted organic pollutants has a structure that facilitates automatic self-cleaning at intervals. A modular construction is used, and three basic types of modules are employed. One of the modules is a TEFLON.RTM. lined carbon steel pipe through which a shuttling scraper is forced at intervals. The shuttling scraper includes an annular wiper that simultaneously cleans the inside surface of the surrounding tubular module as well as the outside surface of an enclosed quartz tube. The annular wiper sealingly engages the quartz tube and the tubular module so that it is driven like a piston by the full pressure of the liquid. When the shuttling scraper has reached the end of the tubular module, it parks itself in a position that causes only minimal pressure drop.