Abstract: An infrared laser absorption spectrometer is disclosed wherein a pair of detector cells are disposed in series relative to the laser beam path, such beam path preferably being within the optical cavity of the laser. The laser beam is modulated to produce a modulation of the absorption, if any, by the sample materials in the two cells. Modulated absorption by the sample or samples produces an acoustic wave in each cell which is detected by a suitable microphone and subtracted so as to produce a difference signal corresponding to the difference in absorption between the two cells so that undesired background effects are cancelled, such as window heating, absorption by a carrier gas or the like which is common to both cells. A mirror placed over one end of one of the cells allows a two cell optoacoustic detector geometry having only two windows therein.

Abstract: The optoacoustic detector cell of an infrared laser optoacoustic spectrometer is interfaced to a source of gas under analysis, such as the atmosphere, by means of a relatively large area membrane separator. Gas to be analyzed is passed through the membrane separator, compressed by a compressor and then fed at a pressure of between 10 and 1000 torr into the optoacoustic detector cell of the infrared spectrometer for analysis therein. A method of tracing is disclosed wherein deuterium is incorporated into a system to be traced. The deuterium diffuses out of the body in extremely minute quantities which are then inducted into the optoacoustic detector cell of an infrared laser optoacoustic spectrometer via a palladium membrane separator and reactor, whereby an extremely sensitive detection or tracing system is obtained.

Abstract: Solid state leaf spring pressure transducers are fabricated by batch photolithographic and etching techniques from a monocrystalline material, such as silicon. The leaf spring structures include elongated gaps separating adjacent leaf spring leg portions from each other and from a surrounding support structure defined by the intervening region of the wafer disposed inbetween adjacent leaf spring structures. An array of fluid tight partitions are sealed at their outer peripheries to the adjacent support structure. Compliant portions of the partitions are individually coupled to individual ones of the spring structures for movement therewith. In one embodiment, the gaps between adjacent leg portions of the individual springs and the surrounding support structure are sealed by a fluid tight web deposited over the major face of the wafer containing the batch of spring structures.

Abstract: An infrared laser absorption spectrometer is disclosed wherein a pair of detector cells are disposed serially along the laser beam path. The laser beam is modulated to produce a modulation of the absorption by the sample materials in the two cells. Modulated absorption by the samples produces an acoustic wave in each cell which is detected by a suitable microphone and subtracted so as to produce a difference signal corresponding to the difference in infrared absorption between the two cells so that undesired background effects common to both cells are cancelled. A pressure controller, which is responsive to the pressure difference between the sample pressure in the two cells at a frequency substantially below the beam modulation frequency is employed for controlling the pressure differential. In one embodiment the pressure controller includes a compliant membrane partitioning the two cells so that the membrane may move so as to equalize the pressures.

Abstract: Composite electrode structures are disclosed employing mutually opposed electrodes spaced apart to define a fluid treatment region through which a fluid is passed for treatment by an electric field established between the electrodes. Resistive electrodes serve to localize the effect of electrical shorts between the electrodes. Refractory electrodes and insulators permit operation in high temperature environments. Non-uniform sheet and/or filamentary electrodes are disclosed for producing a substantial non-uniformity in the electric field within the treatment region for producing forces on particles having no net charge. A floating electrode between driven electrodes allows formation of an induced electric field in the treatment region while reducing the possibility of electrical shorts. Paper electrodes and paper insulators permit fabrication of an inexpensive electrode structure.