Abstract: A system for monitoring survey reflectors arranged at a plurality of locations on an object, having: a camera, including: one or more light sources arranged to illuminate a field in space corresponding to at least 10% of a field of view of the camera, preferably the whole field of view; an image sensor receiving light beams from reflections of the beam by the survey reflectors and providing data; a body with an optical entry system, the image sensor located on a first side and the light source on a second side of the body; and a processing unit processing the data. The processing unit is configured to determine locations of the survey reflectors from the image sensor data and detect movement of the survey reflectors based on a comparison of the determined locations with previously determined locations.

Abstract: A method and sensor system for monitoring in time a geometric property of a gasket (32, 34) that sealingly interconnects two structural members (20, 21) of a subterraneous or immersed tunnel (10). The system includes a sensor (42) for measuring position indications for surface portions (48) of the gasket relative to a reference (26, 27, 47) associated with one or both structural members, and a processor (44) that is coupled with the sensor to receive the position indications. The processor is configured to derive indications of displacement (?Y) for each of the gasket surface portions based on the measured indications of position, to compare the indications of displacement for each of the gasket surface portions with at least one threshold value (Ty), and to generate a warning message for an operator if at least one of the indications of displacement transgresses the at least one threshold value.

Abstract: A camera monitors positions on an external object having a beacon (1(i), i=1, 2, . . . , I; 130; 430) attached to it. The apparatus has at least one image sensor (120; 321, 322; 420; 520), an imaging optical element (101) for projecting light on the image sensor (120), and a processing unit (9). The imaging optical element (101) may be non-refractive and receives a light beam (5(i); 131) transmitted from the beacon (1(i); 130; 430) and transfers the light beam (5(i); 131) to the image sensor (120; 321, 322; 420; 520). The image sensor (120; 321, 322; 420; 520) forms image data based on the received light beam (5(i); 131) and background light. The processing unit (9) processes the image data such that it filters image data components relating to the background light and renders image data components relating to the light beam.

Abstract: A system for monitoring survey reflectors arranged at a plurality of locations on an object, having: a camera, including: one or more light sources arranged to illuminate a field in space corresponding to at least 10% of a field of view of the camera, preferably the whole field of view; an image sensor receiving light beams from reflections of the beam by the survey reflectors and providing data; a body with an optical entry system, the image sensor located on a first side and the light source on a second side of the body; and a processing unit processing the data. The processing unit is configured to determine locations of the survey reflectors from the image sensor data and detect movement of the survey reflectors based on a comparison of the determined locations with previously determined locations.

Abstract: An observation unit (30) for underwater deployment on/in a submerged earth layer (12) or structure. The unit comprises a housing (32), a light source (36), an underwater imaging device (40), a processor device (44), and a communication device (35). The housing supports the underwater observation unit relative to the submerged layer or structure. The light source is fixed to the housing, and configured to emit light into the unit's surroundings. The imaging device is attached to the housing, and configured to acquire image data of a second light source located within a FOV of the camera that covers the surroundings of the unit. The processor device is configured to determine positional data of the second light source relative to the imaging device, from the image data. The communication device is configured to transmit the positional data to another underwater observation unit, an underwater vehicle, or an underwater processing station.

Abstract: An underwater wireless optical communication, UWOC, unit (30) for underwater deployment on a submerged earth layer (12) or structure (14, 16). The UWOC unit is configured for wireless optical communication in an underwater environment, and comprises an optical transmitter (36), an anidolic optical receiver (38), and a processor (44). The optical transmitter is configured to transmit data by emitting an optical signal (80) into the surroundings. The optical receiver includes an optical detector (62), which is omnidirectionally sensitive and configured to receive further optical signals approaching substantially along an azimuthal plane orthogonal to a nominal axis (A) through the UWOC unit. The processor is coupled to the optical receiver, and configured to process received further optical signals.

Abstract: An apparatus monitors positions on an external object having at least one beacon (1(i), i=1, 2, . . . , I) attached to it. The apparatus has an image sensor (11), a lens system (13) and a processing unit (9). The lens system (13) receives at least one light beam (5(i)) transmitted from the at least one beacon (1(i)) and transfer the at least one light beam (5(i)) to the image sensor (11). The image sensor (11) forms image data. The processing unit (9) identifies the at least one beacon (1(i)) within the image data based on the at least one light beam (5(i)), determines current location data of the at least one beacon (1(i)) based on the image data, compares the current location data with former location data of the one or more beacons (1(i)) as stored in a memory (15) and determines whether the object has moved relative to a fixed reference frame based on the comparison.

Abstract: A receiver (30) for providing an activation signal (54) to transition a device from a dormant state to an operative state. The receiver includes a sensor (32), a super regenerative oscillator, SRO, circuit (34), and a processing device (36, 38). The sensor is one of an optical sensor, an acoustic sensor, and a magnetic field sensor, and generates detector signals (40) based on wireless signals (28) received from an external source (18). The SRO circuit is electrically coupled to the sensor to receive the detector signals, and electrically oscillates with a constant SRO frequency and with a SRO amplitude (As) that changes when a carrier frequency of the detector signal substantially matches the SRO frequency. The processing device monitors the SRO amplitude in time, and generates the activation signal when a temporal characteristic (Sc) of the monitored SRO amplitude matches a predetermined reference pattern (52).

Abstract: A receiver (30) for providing an activation signal (54) to transition a device from a dormant state to an operative state. The receiver includes a sensor (32), a super regenerative oscillator, SRO, circuit (34), and a processing device (36, 38). The sensor is one of an optical sensor, an acoustic sensor, and a magnetic field sensor, and generates detector signals (40) based on wireless signals (28) received from an external source (18). The SRO circuit is electrically coupled to the sensor to receive the detector signals, and electrically oscillates with a constant SRO frequency and with a SRO amplitude (As) that changes when a carrier frequency of the detector signal substantially matches the SRO frequency. The processing device monitors the SRO amplitude in time, and generates the activation signal when a temporal characteristic (Sc) of the monitored SRO amplitude matches a predetermined reference pattern (52).

Abstract: An underwater wireless optical communication, UWOC, unit (30) for underwater deployment on a submerged earth layer (12) or structure (14, 16). The UWOC unit is configured for wireless optical communication in an underwater environment, and comprises an optical transmitter (36), an anidolic optical receiver (38), and a processor (44). The optical transmitter is configured to transmit data by emitting an optical signal (80) into the surroundings. The optical receiver includes an optical detector (62), which is omnidirectionally sensitive and configured to receive further optical signals approaching substantially along an azimuthal plane orthogonal to a nominal axis (A) through the UWOC unit. The processor is coupled to the optical receiver, and configured to process received further optical signals.

Abstract: A sensor circuit (10), including a silicon photomultiplier, SiPM, sensor (20), a voltage source (32), a current-to-voltage converter (24), and a limiting bias circuit (34). The SiPM sensor (20) has avalanche photodiode, APD, elements (30) connected in parallel between a cathode (K) and an anode (A). The voltage source (32) is configured to apply a reversed bias voltage (Vb) across the SiPM sensor, so that each APD element operates in reverse-biased Geiger mode, and the APD elements operate in integration mode. The bias circuit (34) is connected between the voltage source (32) and the anode, and is configured to limit currents through the APD elements, and to present an AC load impedance for an alternating current within a predetermined operating frequency range (fo) generated by the APD elements at the anode (A) as well as a DC load impedance, such that said AC load impedance is lower than said DC load impedance.

Abstract: A method and sensor system for monitoring in time a geometric property of a gasket (32, 34) that sealingly interconnects two structural members (20, 21) of a subterraneous or immersed tunnel (10). The system includes a sensor (42) for measuring position indications for surface portions (48) of the gasket relative to a reference (26, 27, 47) associated with one or both structural members, and a processor (44) that is coupled with the sensor to receive the position indications. The processor is configured to derive indications of displacement (?Y) for each of the gasket surface portions based on the measured indications of position, to compare the indications of displacement for each of the gasket surface portions with at least one threshold value (Ty), and to generate a warning message for an operator if at least one of the indications of displacement transgresses the at least one threshold value.

Abstract: An observation unit (30) for underwater deployment on/in a submerged earth layer (12) or structure. The unit comprises a housing (32), a light source (36), an underwater imaging device (40), a processor device (44), and a communication device (35). The housing supports the underwater observation unit relative to the submerged layer or structure. The light source is fixed to the housing, and configured to emit light into the unit's surroundings. The imaging device is attached to the housing, and configured to acquire image data of a second light source located within a FOV of the camera that covers the surroundings of the unit. The processor device is configured to determine positional data of the second light source relative to the imaging device, from the image data. The communication device is configured to transmit the positional data to another underwater observation unit, an underwater vehicle, or an underwater processing station.

Abstract: A camera monitors positions on an external object having a beacon (1(i), i=1, 2, . . . , I; 130; 430) attached to it. The apparatus has at least one image sensor (120; 321, 322; 420; 520), an imaging optical element (101) for projecting light on the image sensor (120), and a processing unit (9). The imaging optical element (101) may be non-refractive and receives a light beam (5(i); 131) transmitted from the beacon (1(i); 130; 430) and transfers the light beam (5(i); 131) to the image sensor (120; 321, 322; 420; 520). The image sensor (120; 321, 322; 420; 520) forms image data based on the received light beam (5(i); 131) and background light. The processing unit (9) processes the image data such that it filters image data components relating to the background light and renders image data components relating to the light beam.

Abstract: A sensor circuit (10), including a silicon photomultiplier, SiPM, sensor (20), a voltage source (32), a current-to-voltage converter (24), and a limiting bias circuit (34). The SiPM sensor (20) has avalanche photodiode, APD, elements (30) connected in parallel between a cathode (K) and an anode (A). The voltage source (32) is configured to apply a reversed bias voltage (Vb) across the SiPM sensor, so that each APD element operates in reverse-biased Geiger mode, and the APD elements operate in integration mode. The bias circuit (34) is connected between the voltage source (32) and the anode, and is configured to limit currents through the APD elements, and to present an AC load impedance for an alternating current within a predetermined operating frequency range (fo) generated by the APD elements at the anode (A) as well as a DC load impedance, such that said AC load impedance is lower than said DC load impedance.

Abstract: An apparatus monitors positions on an external object having at least one beacon (1(i), i=1, 2, . . . , I) attached to it. The apparatus has an image sensor (11), a lens system (13) and a processing unit (9). The lens system (13) receives at least one light beam (5(i)) transmitted from the at least one beacon (1(i)) and transfer the at least one light beam (5(i)) to the image sensor (11). The image sensor (11) forms image data. The processing unit (9) identifies the at least one beacon (1(i)) within the image data based on the at least one light beam (5(i)), determines current location data of the at least one beacon (1(i)) based on the image data, compares the current location data with former location data of the one or more beacons (1(i)) as stored in a memory (15) and determines whether the object has moved relative to a fixed reference frame based on the comparison.