Abstract: An apparatus includes first and second light sources for respectively generating broadband and monochromatic lights, a beamsplitter optically coupled to the first light source for splitting the broadband light into a reference light and a sample light, a reference arm optically coupled to the beamsplitter for receiving the reference light and returning the received reference light into the beamsplitter, a sample arm optically coupled to the beamsplitter and the second light source for combining the sample and monochromatic lights, delivering the combined light to the target of interest, collecting a backscattering light and a Raman scattering light generated from interaction of the combined light with the target of interest, returning the backscattering light into the beamsplitter so as to generate an interference signal between the returned backscattering light and the returned reference light in the beamsplitter, and directing the Raman scattering light in an output optical path.

Abstract: A photo acoustic trace gas detector for detecting a concentration of a trace gas in a gas mixture. The detector includes a light source for producing a light beam and a light modulator for modulating the light beam into a series of light pulses for generating sound waves in the gas mixture. The light modulator is arranged for modulating the light beam between a non-zero lower intensity level and a higher intensity level. An amplitude of the sound waves being a measure of the concentration. An optical cavity contains the gas mixture and amplifies a light intensity of the light pulses. A transducer converts the sound waves into electrical signals. A feedback loop with a photo detector for measuring the light intensity of the light pulses regulates the amplification of the light intensity in the optical cavity.

Abstract: In one aspect of the present invention, an apparatus includes a first light source for generating a broadband light, and a second light source for generating a monochromatic light, a beamsplitter optically coupled to the first light source for receiving the broadband light and splitting the received broadband light into a reference light and a sample light, a reference arm optically coupled to the beamsplitter for receiving the reference light and returning the received reference light into the beamsplitter, and a sample arm optically coupled to the beamsplitter and the second light source for combining the sample light and the monochromatic light, delivering the combined sample and monochromatic light to the target of interest, collecting a backscattering light and a Raman scattering light that are generated from interaction of the sample light and the monochromatic light with the target of interest, respectively, returning the backscattering light into the beamsplitter so as to generate an interference sign

Abstract: A photo acoustic trace gas detector (100) is provided for detecting a concentration of a trace gas in a gas mixture. The detector (100) comprises a light source (101) for producing a light beam and a light modulator (103) for modulating the light beam into a series of light pulses at a chopping frequency for generating sound waves in the gas mixture. The amplitude of the sound waves is a measure of the concentration of the trace gas. The detector (100) further comprises an optical cavity (104a, 104b) with the gas mixture. The optical cavity (104a, 104b) amplifies the light intensity of the light pulses. A transducer (109) converts the sound waves into electrical signals. A feed back loop (110, 111, 113, 114) regulates a ratio of a length of the optical cavity (104a, 104b) and a wavelength of the light beam for amplifying the light intensity of the light pulses in the optical cavity (104a, 104b).

Abstract: An oscillator element is provided, e.g., for use in a photo acoustic detector for detecting a concentration of a sample in a sample mixture using a light beam for excitation of molecules of the sample in proximity of an excitation area of the oscillator element. The oscillator element includes piezoelectric material for generating a voltage when mechanically distorted. Electrodes at least partially cover a surface of the oscillator element for detecting the generated voltage. The excitation area is arranged in such a way that heating of the electrodes in the excitation area by the light beam is avoided.

Abstract: A photo acoustic detector for detecting a concentration of a sample in a sample mixture, the photo acoustic detector has a light source for producing a light beam for exciting molecules of the sample, a light modulator for modulating an intensity of the light beam for generating pressure variations in the sample mixture, an amplitude of the pressure variations being a measure of the concentration of the sample, and an acoustic cell with an acoustic resonator for amplifying the pressure variations. Furthermore, the photo acoustic detector has a resonant pickup element for converting the pressure variations inside the acoustic resonator into a detector signal, and a processing section for processing the detector signal to generate 1) a sample signal caused by the pressure variations, and 2) a background signal caused by direct excitation of the pickup element by the light beam.

Abstract: A device (100) for measuring a concentration of NO in exhaled air is provided. The device (100) comprises a mouthpiece (11), an NO sensor (12), an airway obstruction measurement and an analysis module. The mouthpiece (11) receives the exhaled air during an exhalation. The NO sensor (12) measures the concentration of NO in the exhaled air. The airway obstruction measurement module determines an airway obstruction parameter. The analysis module (16) analyzes an inflammatory status of a respiratory system based on a combination of the measured concentration of NO and the determined airway obstruction parameter.

Abstract: An oscillator element (10) for use in a photo acoustic detector is provided for detecting a concentration of a sample in a sample mixture. The photo acoustic detector uses a light beam (11) for excitation of molecules of the sample (15) in proximity of an excitation area (25) of the oscillator element (10). The excitation results in resonance of the oscillator element (10). The oscillator element (10) comprises piezoelectric material (20) for generating a voltage when mechanically distorted and electrodes (21-24), at least partially covering a surface of the oscillator element (10) for registering the generated voltage. The excitation area (25) is arranged in such a way that heating of the electrodes (21-24) in the excitation area (25) by the light beam (11) is avoided.

Abstract: A photo acoustic trace gas detector (100) is provided for detecting a concentration of a trace gas in a gas mixture. The detector (100) comprises a light source (101) for producing a light beam and a light modulator (103) for modulating the light beam into a series of light pulses at a chopping frequency for generating sound waves in the gas mixture. The amplitude of the sound waves is a measure of the concentration of the trace gas. The detector (100) further comprises an optical cavity (104a, 104b) with the gas mixture. The optical cavity (104a, 104b) amplifies the light intensity of the light pulses. A transducer (109) converts the sound waves into electrical signals. A feed back loop (110, 111, 113, 114) regulates a ratio of a length of the optical cavity (104a, 104b) and a wavelength of the light beam for amplifying the light intensity of the light pulses in the optical cavity (104a, 104b).

Abstract: A photo acoustic trace gas detector (100) is provided for detecting a concentration of a trace gas in a gas mixture. The detector (100) comprises a light source (101) for producing a light beam and a light modulator (103) for modulating the light beam into a series of light pulses for generating sound waves in the gas mixture. The light modulator (103) is arranged for modulating the light beam between a non-zero lower intensity level and a higher intensity level. An amplitude of the sound waves being a measure of the concentration. An optical cavity (104a, 104b) contains the gas mixture and amplifies a light intensity of the light pulses. A transducer (109) for converts the sound waves into electrical signals. A feed back loop (110, 111) with a photo detector (110) for measuring the light intensity of the light pulses regulates the amplification of the light intensity in the optical cavity (104a, 104b).

Abstract: A photo acoustic trace gas detector (100) is provided for detecting a concentration of a trace gas in a gas mixture. The photo acoustic trace gas detector (100) comprises a light source (101), an optical cavity (104a, 104b), ratio modulating means (105, 111) and a transducer (109). The optical cavity (104a, 104b) contains the gas mixture and amplifies light intensity. Maximum amplification is provided when a ratio of a wavelength of the light beam and a length of the optical cavity (104a, 104b) has a resonance value. Ratio modulating means (105, 111) modulate the ratio for transformation of the light beam into a series of light pulses for generating the sound waves, an amplitude of the sound waves being a measure of the concentration of the trace gas. A transducer (109) converts the sound waves into electrical signals.