Abstract: An optical displacement sensor comprises a reflective surface and one or more diffraction gratings which, together with the reflective surface, each define a respective interferometric arrangement. The reflective surface is moveable relative to the diffraction grating(s) or vice versa. Light from a light source propagates via the interferometric arrangement(s) to produce an interference pattern at a respective set of photo detectors. Each interference pattern depends on the separation between the reflective surface and the respective grating. A collimating optical arrangement at least partially collimates the light between the light source and the diffraction grating(s).

Abstract: A gas sensor (2) distinguishes between a target gas and a contaminant and includes a light source (8), a measurement volume (4), a detector (22), and an adaptable filter system (20) with a first optical filter and a second optical filter. The filter system switches between a first composite state, with both filters in a reference state, a second composite state, with the first filter in a first reference state and the second filter in a second measurement state, a third composite state with the first filter in a first measurement state and the second filter in a second reference state, and a fourth composite state, with both filters in a measurement state. The gas sensor detects a target gas and makes a determination as to a presence of the contaminant by comparing the respective detector signals, generated during at least three of the composite states, with each other.

Abstract: An optical microphone assembly including a substrate, an interferometric arrangement, a light source, and at least one photo detector. The interferometric arrangement includes a membrane and at least one diffractive optical element spaced from the membrane. The diffractive optical element(s) include a plurality of lines formed in or disposed on a surface of the substrate and arranged in a first pattern. The substrate includes one or more holes extending fully therethrough, the hole(s) arranged in a second pattern that is different from the first pattern. The light source is arranged to provide light to the interferometric arrangement such that first and second portions of the light propagate along respective, different first and second optical paths via the interferometric arrangement. An optical path difference between the first and second optical paths depends on a distance between the membrane and the diffractive optical element(s).

Abstract: A gas sensor for measuring concentration of a predetermined gas includes a light source (2) arranged to emit pulses of light, a measurement volume (10), a detector (4) arranged to receive light that has passed through the measurement volume (10), and an adaptable filter (6) disposed between the light source (2) and the detector (4). The gas sensor has a measurement state in which it passes at least one wavelength band which is absorbed by the gas and a reference state in which said wavelength band is attenuated relative to the measurement state. A controller is connected to each of the light source, the detector and the adaptable filter to change the adaptable filter between one of said measurement state and said reference state to the other at least once during a gas sensor operation period.

Abstract: An optical microphone assembly including a micro-electromechanical system (MEMS) component, a semiconductor chip, and an outer housing including at least part of a non-MEMS supporting structure and defining an aperture. The MEMS component includes an interferometric arrangement which includes a membrane and at least one optical element spaced from the membrane. The semiconductor chip includes at least one photo detector and a light source. The MEMS component is mounted on the non-MEMS supporting structure and sealed to the outer housing such that the MEMS component closes the aperture. The semiconductor chip is mounted separately from the MEMS component on the non-MEMS supporting structure in a spaced relationship with the MEMS component such that the MEMS component is displaced relative to the semiconductor chip in a direction perpendicular to a reflecting surface of the membrane.

Abstract: A gas sensor (2) distinguishes between a target gas and a contaminant and includes a light source (8), a measurement volume (4), a detector (22), and an adaptable filter system (20) with a first optical filter and a second optical filter. The filter system switches between a first composite state, with both filters in a reference state, a second composite state, with the first filter in a first reference state and the second filter in a second measurement state, a third composite state with the first filter in a first measurement state and the second filter in a second reference state, and a fourth composite state, with both filters in a measurement state. The gas sensor detects a target gas and makes a determination as to a presence of the contaminant by comparing the respective detector signals, generated during at least three of the composite states, with each other.

Abstract: A gas sensor for measuring concentration of a predetermined gas includes a light source (2) arranged to emit pulses of light, a measurement volume (10), a detector (4) arranged to receive light that has passed through the measurement volume (10), and an adaptable filter (6) disposed between the light source (2) and the detector (4). The gas sensor has a measurement state in which it passes at least one wavelength band which is absorbed by the gas and a reference state in which said wavelength band is attenuated relative to the measurement state. A controller is connected to each of the light source, the detector and the adaptable filter to change the adaptable filter between one of said measurement state and said reference state to the other at least once during a gas sensor operation period.

Abstract: A gas sensor is used for determining a concentration of a predetermined gas in a measurement volume. The gas sensor comprises a light source and a detector arranged to receive light that has passed through the measurement volume. During a first measurement period, the detector is used to make a first measurement of an amount of light received in at least one wavelength band which is absorbed by the gas. The first measurement is compared to a predetermined threshold value. If the threshold is crossed, during a second measurement period the detector is used to make a second measurement of an amount of light received in at least one wavelength band which is absorbed by the gas. The concentration of said gas in said measurement volume is calculated using the first and/or second measurement.

Abstract: A gas sensing apparatus (48) comprises a gas sensor arranged to use light to sense presence of a gas; an optical element (12, 40) arranged so that said light impinges thereon; and a thermoelectric heat pump (2, 24) having a cold side (6, 36) and a hot side (8, 34). The thermoelectric heat pump (2, 24) is configured to transfer heat energy from said cold side (6, 36) to said hot side (8, 34) in response to a supply of electrical energy provided to the thermoelectric heat pump (2, 24). The hot side (8, 34) of the thermoelectric heat pump (2, 24) is in thermal contact with the optical element (12, 40).

Abstract: A gas sensor is used for determining a concentration of a predetermined gas in a measurement volume. The gas sensor comprises a light source and a detector arranged to receive light that has passed through the measurement volume. During a first measurement period, the detector is used to make a first measurement of an amount of light received in at least one wavelength band which is absorbed by the gas. The first measurement is compared to a predetermined threshold value. If the threshold is crossed, during a second measurement period the detector is used to make a second measurement of an amount of light received in at least one wavelength band which is absorbed by the gas. The concentration of said gas in said measurement volume is calculated using the first and/or second measurement.

Abstract: A gas sensing apparatus (48) comprises a gas sensor arranged to use light to sense presence of a gas; an optical element (12, 40) arranged so that said light impinges thereon; and a thermoelectric heat pump (2, 24) having a cold side (6, 36) and a hot side (8, 34). The thermoelectric heat pump (2, 24) is configured to transfer heat energy from said cold side (6, 36) to said hot side (8, 34) in response to a supply of electrical energy provided to the thermoelectric heat pump (2, 24). The hot side (8, 34) of the thermoelectric heat pump (2, 24) is in thermal contact with the optical element (12, 40).

Abstract: A gas sensor is used for determining a concentration of a predetermined gas in a measurement volume. The gas sensor comprises a light source and a detector arranged to receive light that has passed through the measurement volume. During a first measurement period, the detector is used to make a first measurement of an amount of light received in at least one wavelength band which is absorbed by the gas. The first measurement is compared to a predetermined threshold value. If the threshold is crossed, during a second measurement period the detector is used to make a second measurement of an amount of light received in at least one wavelength band which is absorbed by the gas. The concentration of said gas in said measurement volume is calculated using the first and/or second measurement.

Abstract: A gas sensor for measuring concentration of a predetermined gas comprises a light source arranged to emit pulses of light, a measurement volume, a detector arranged to receive light that has passed through the measurement volume, and an adaptable filter disposed between the light source and the detector. The gas sensor has a measurement state in which it passes at least one wavelength band which is absorbed by the gas and a reference state in which said wavelength band is attenuated relative to the measurement state. The adaptable filter is arranged to change between one of said measurement state and said reference state to the other at least once during each pulse.

Abstract: A gas sensor is used for determining a concentration of a predetermined gas in a measurement volume. The gas sensor comprises a light source and a detector arranged to receive light that has passed through the measurement volume. During a first measurement period, the detector is used to make a first measurement of an amount of light received in at least one wavelength band which is absorbed by the gas. The first measurement is compared to a predetermined threshold value. If the threshold is crossed, during a second measurement period the detector is used to make a second measurement of an amount of light received in at least one wavelength band which is absorbed by the gas. The concentration of said gas in said measurement volume is calculated using the first and/or second measurement.

Abstract: This invention relates to an interference filter, especially for use in gas detection with infrared light within a chosen range, comprising at least two essentially parallel and partially reflective surfaces with a chosen distance between them thus defining a cavity delimited by the reflecting surfaces between which the light may oscillate, and wherein at least one of said surfaces is partially transparent for transmission of light to or from said cavity. The filter comprises a first transparent material having a high refractive index, e.g. silicon, positioned in at least a part of said cavity, and at least one of said reflective surfaces being divided into a three dimensional pattern with varying shift relative to its plane, thus to provide a position dependent resonance condition between them for separation of different wavelengths in the light.

Abstract: The present invention relates to an adjustable interference filter, especially for use in gas detection with infrared light within a chosen range, comprising at least two essentially parallel reflective surfaces separated by a chosen distance defining a cavity delimited by the reflective surfaces between which the light may oscillate, and at least one of said surfaces being semitransparent for transmission of light to or from the cavity. The filter comprises a transparent material with a chosen thickness and having a high refractive index positioned in the cavity, and adjustable separation means for adjusting the cavity length between the reflecting surfaces, so as to obtain a cavity constituted by the transparent, high refractive index material and a an adjustable part.

Abstract: The invention relates an optical displacement sensor element comprising two essentially flat surfaces (1,2) being separated by a cavity defined by a spacer (5) and the surfaces (1,2), the distance between the surfaces being variable, wherein a first of said surfaces (1) is positioned on an at least partially transparent carrier (3) and being provided with a reflective pattern, the pattern constituting a pattern being shaped as a diffractive lens, and said second surface (2) being a reflective surface.

Abstract: A method and apparatus for identifying a material type in an article, such as wholly or partly transparent bottle of plastic or glass, including, with the aid of a detector station, irradiating the article with rays from an infrared radiation source, detecting rays which have passed through the article non-absorbed, and then carrying out a correlation analysis of such detected rays. The article is made to pass through the detector station in a continuous or discontinuous movement. The rays from the radiation source are successively filtered by the filters consisting of wholly or partly transparent materials which have different spectral characteristics. The rays filtered by the filters and non-absorbed by the article are intercepted in order to form a sequence of measured values representing characteristic transmission signatures of the article. A correlation analysis of the signatures is carried out in relation to statistical models in order to determine the material type of the article.