An example of a system comprises a volume filled with a gas, a gas excitation device configured to excite the gas inside the volume, a microphone configured to output a microphone signal on the basis of the gas excited by the gas excitation device, and a testing unit configured to take the microphone signal as a basis for testing a gas-tightness of the volume. An example of a photoacoustic sensor comprises a hermetically sealed sensor cell, a gas excitation device and a testing unit configured to take the microphone signal dependent on the thermally excited gas as a basis for testing a gas-tightness of the sensor cell. One example comprises a method for testing a gas-tightness of a volume filled with a gas.

Disclosed is an apparatus for and method of measuring the concentration of F2 in the laser gas used in an excimer laser. Quartz Enhanced Photoacoustic Spectroscopy is used to obtain a direct measurement of F2 concentration quickly and using only a small sample volume.

A system is used to excite an object at a vibration frequency, in order to induce stationary or travelling waves having the vibration frequency on the surface of the object. An optical interferometer is configured to use optical interference to determine vibration amplitude and phase data of the stationary or travelling wave at each of a plurality of points on the surface, relative to a reference phase. A processing system is used to apply a spatial derivative filter to the vibration phase data, and the resulting spatial-derivative-of-phase data is processed to determine a property of the object, and is further processed to generate graphical-representation data for outputting on a display device.

A downhole system includes a quartz enhanced photoacoustic spectrometer (QEPAS) configured to be positioned within a wellbore formed in a subterranean zone of a hydrocarbon formation, a sampling system coupled to the QEPAS, and a computer system connected to the QEPAS. The sampling system is configured to be positioned in the wellbore and obtain a sample of a wellbore fluid at a downhole location in the subterranean zone. The QEPAS is configured to spectroscopically scan the sample and to determine a plurality of quantities of a corresponding plurality of hydrocarbons in the same. The computer system includes one or more processors to perform operations including receiving the plurality of quantities of the plurality of hydrocarbons in the sample and determining a plurality of ratios, where each ratio is a ratio of one of the plurality of hydrocarbons with another of the plurality of hydrocarbons.

Apparatus for performing multiple different measurements on a small specimen sample, enabling testing and diagnoses in real time at the point of care are described. The core of the apparatus includes an ultrasonic resonator cavity where acoustic resonances are used to determine the speed of sound and sound attenuation in a single droplet. Acoustic measurements are made in the reflection mode using electrical impedance of a small piezoelectric crystal transducer that operates in the thickness longitudinal mode. Combination of this technology with electromagnetic, electrical, and magnetic fields permits multiple types of measurements to be made using the same resonator cavity.

The present invention relates to an optical gas detector for detecting a gas absorbing light at a known wavelength, wherein the gas detector comprises two essentially identical, parallel membranes defining a volume between them containing the gas to be investigated, and a modulated first light source emitting light at said known wavelength into said volume at a chosen frequency, the detector is adapted to detect relative movements between said membranes and said movements having a frequency corresponding to the rate or a multiple of the rate of said pulsed light source, and wherein the said volume has at least one opening allowing the gas to unrestricted flow or diffuse into said volume.

Systems and methods for estimating the location of a wave source based upon low frequency measurements acquired using multiple receivers. In one aspect, a method for estimating an end range of a radiation beam delivered to a target is provided. The method includes controlling a radiation treatment system to deliver a radiation beam inducing at least one low frequency thermoacoustic wave inside a target, and detecting, using receivers positioned about the target, sonic signals corresponding to the at least one low frequency thermoacoustic wave. The method also includes analyzing the sonic signals to determine differences in times-of-flight associated with different receivers, and estimating an end range of the radiation beam by correlating the differences in times-of-flight. The method further includes generating a report indicative of the end range of the radiation beam.

A system and method are described for determining properties of particulates. The device collects particulates on the surface of an oscillating balance and compares the natural resonant frequency of the balance with the particulates with a balance without particulates. In addition, the collected particulates are illuminated with light that is absorbed by the particulates. This causes the balance to heat up, affecting the natural resonant frequency. A comparison of the natural resonant frequencies reveals optical properties of the collected particulates, which may be used to speciate the particulates.

An acoustic probe includes a plurality of transducers that receives acoustic waves and a supporting body including a supporting portion having a symmetrical concave surface, such as a spherical cap surface, which supports the transducers in a spiral array. The supporting position R at which the supporting portion supports the transducers is given as R(r.sub.0, , ) [m, rad, rad] by a polar coordinate with respect to a center of the symmetrical concave surface by setting a sphere radius, a zenith angle, and an azimuth angle as r.sub.0, , and , wherein the plurality of transducers is arrayed at a set azimuth angle spiral pitch in an azimuth angle direction and an axis direction spiral pitch set parallel to a central axis direction of the symmetrical concave surface, and wherein the azimuth angle spiral pitch is an angle acquired by dividing 2 by 1+golden number.

A photoacoustic gas analyzer, including: a gas chamber to receive a gas to be analyzed; a radiation source that emits into the gas chamber electromagnetic radiation with a time-varying intensity to excite gas molecules of N mutually different gas types the concentrations of which are to be determined in the received gas, wherein the radiation source is operable in N mutually different modes, each mode having a unique emission spectrum different from the emission spectra of the other N-1 modes; an acoustic-wave sensor that detects acoustic waves generated by the electromagnetic radiation emitted into the gas to be analyzed; and a control unit to operate the radiation source in the different modes respectively to emit electromagnetic radiation with a time-varying intensity; to receive in each mode from the acoustic-wave sensor signals; and to determine from the signals received in each mode the concentrations of the N mutually different gas types.