Distributed optical sensing devices and methods performing a measurement

A distributed optical sensing device, the device comprising:

• a first light detector having a first light sensitivity and configured to detect light backscattered in a first distance range of an optical fiber;
• and
• a second light detector different to the first light detector and having a second light sensitivity being higher than the first light sensitivity,
• wherein the second light detector is configured to detect light backscattered in a second distance range of an optical fiber being farther away from the second light detector than the first distance range is away from the first light detector.

A distributed optical sensing device, comprising:

• an optical fiber;
• a light source coupled to the optical fiber and configured to input a light pulse into the optical fiber;
• and
• at least one photon counting type detector having a dynamic range having an upper boundary and a lower boundary, being coupled to the optical fiber and being configured to measure light backscattered from a distance range of the optical fiber and to generate a signal indicative of the amount of the detected backscattered light,
• wherein the distributed optical sensing device is configured to restrict the generated signal to the dynamic range while maintaining a strength of the inputted light pulse.

A distributed optical sensing device, comprising:

• an optical fiber;
• a light source coupled to the optical fiber and configured to input a light pulse into the optical fiber;
• at least one photon counting type detector having an input terminal optically coupled to the optical fiber and configured to receive the backscattered light pulse;
• and
• a variable attenuator arranged before the input terminal,
• wherein the distributed optical sensing device is configured to modify an attenuation of the backscattered light pulse during a single measuring cycle by the variable attenuator.

A method of performing a measurement by a distributed optical sensing device comprising an optical fiber, the method comprising:

• performing a first measurement wherein light of a light pulse backscattered in a first distance range of the optical fiber is measured by a first light detector having a first light sensitivity;
• performing a second measurement wherein light of the light pulse backscattered in a second distance range of the optical fiber is measured by a second light detector having a second light sensitivity being higher than the first light sensitivity, wherein the second distance range is farther away from the second light detector than the first distance range is away from the first light detector;
• and
• combining the first measurement and the second measurement to a combined measurement.

A method of performing a measurement by a distributed optical sensing device comprising an optical fiber;

• a light source;
• and at least one photon counting type detector having an input terminal optically coupled to the optical fiber, wherein the method comprises:
• inputting a light pulse emitted by a light source into the optical fiber;
• attenuating, by a variable attenuator, a backscattered light portion of the light pulse backscattered in the optical fiber during a single measuring cycle before the backscattered light portion enters the input terminal of the at least one photon counting type detector.