Abstract: A detector for a gas analyzer includes a thermal detector, an absorptive film on the surface of said thermal detector, and an enclosure containing a reference gas of the gas species of interest such that the thermal detector is in thermal contact with both the absorptive film and the reference gas. During irradiation, the absorptive film absorbs radiation which passes through the reference gas and causes the thermal detector to generate a corresponding output. When the irradiation is terminated, the heat content of the reference gas, which will be dependent upon the amount of the radiation absorbed, will be communicated to the thermal detector to cause the thermal detector to provide a second output representing the amount of radiation absorbed by the reference gas.

Abstract: A process for purifying hydrocarbonaceous oils containing heteroatom sulfur and heteroatom nitrogen compound impurities comprising the steps of:(1) reacting said hydrocarbonaceous oil with an oxidizing gas containing at least one nitrogen oxide with more than one oxygen atom for each nitrogen atom while maintaining(a) the molar ratio of the nitrogen oxide to the total of the sulfur heteroatom content and the nitrogen heteroatom content to about 1.5:1 or less,(b) the reaction time to about one hour or less,(c) the temperature to about 100.degree. C.

Abstract: A method and apparatus for operating a dual-frequency gas laser so as to controllably switch between frequencies makes use of a cavity so tuned that the comb of resonant frequencies is not commensurate with the frequency difference between the laser operating frequencies, and, in a preferred embodiment, with one of the resonant frequencies tuned to coincide with one of the operating frequencies. The cavity length and overall gain at each frequency are so selected that the spacing between resonant frequencies is greater than the breadth above unity gain of the individual peaks of the gain vs. frequency curve. The active material is subjected to a magnetic field which may be varied in a controlled manner. In a preferred embodiment, this field is applied normal to the optical axis of the resonant cavity, and an optical element within the cavity is arranged to act as a plane polarizer with its plane of polarization normal to the magnetic field.

Abstract: A method of making a light equalizer comprises the steps of selecting a powdered crystalline material capable of being compressed to form a body transparent to selective wavelengths of light. The material is compressed to a point short of complete transparency so as to provide a plurality of light scattering centers throughout the bulk of the body. A stack of the bodies are formed in which the bodies are disposed along a common axis. The exterior surfaces of the stack thus formed are covered with an internally reflective coating except for two opposite ends thereof, so that light of selected wavelengths transmitted through the stack will be substantially uniformly distributed at the output of the stack.

Abstract: A method of making a light equalizer comprises the steps of mixing two different powdered crystalline materials, each of a slightly different index of refraction so as to provide scattering of selected wavelengths of light. The materials are compacted under pressure to form an integral body containing a plurality of light scattering centers. The exterior surfaces of the body are covered with a reflective coating except for two opposite ends through which the selected wavelengths of light can be transmitted so as to provide a substantially uniform distribution of light at its output.

Abstract: A methane detector comprising a He-Ne laser in which the plasma tube forms a portion of the resonant cavity and the laser can be stimulated to emit at two different atomic resonances at separate wave numbers .nu..sub.1 and .nu..sub.2, one of which is more strongly absorbed by methane than the other. Means such as a beam splitter disposed in the resonant cavity, are provided for directing two beams outwardly from the cavity to a pair of detectors each provided in the path of a respective beam. The cavity is tuned so that its length L meets the criterion m/2L = .nu..sub.1 -.nu..sub.2, m being a number of half integers. Means are provided for cyclically varying the gain of the laser across one free spectral range through some tuned center value.

Abstract: An optical system is provided to minimize the angle-dependent transmission characteristics of interference filters, the optical system including a light equalizer having an output aperture across which each area element exhibits substantially the same emission intensity regardless of the distribution of light into the input aperture of the equalizer. The output aperture of the equalizer is disposed at the focal surface of collimating optics and the resultant collimated light constitutes the input to the interference filter.The equalizer is embodied in a transmissive element which is divided into pairs of transmissive channels, the number of such pairs increasing with the distance from the input aperture. The interface between the adjacent channels is, at least in part, leaky as by being substantially half transmissive half reflective. The exterior surface of the equalizer is covered with an internally reflective coating except for the input and output apertures.

Abstract: A light equalizer having an output aperture across which each area element exhibits substantially the same emission intensity regardless of the distribution of light into the input aperture of the equalizer. The equalizer is embodied in a stack of a plurality of transmissive elements, a number of which provide a multiplicity of light scattering centers. The exterior surface of the equalizer is covered with an internally reflective coating except for the input and output apertures.