GB1603275A

GB1603275A - Optical fibre transmission instrumentation

Info

Publication number: GB1603275A
Application number: GB2001078A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-05-16
Filing date: 1978-05-16
Publication date: 1981-11-25

Description

(71) I DENNIS WILLIAM BuRT of British Nationality, of The Bungalow, Woodhouse Lane, Moulton Loosegate, Spalding, Lincs., do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a new range of analogue instrumentation based upon optical fibre instead of electrical cable transmission.

Each analogue instrument comprises an optical/ electro convertor (OEC) at the remote indication end and a mechanical/optical convertor (MOC) at the transmitter end, the two convertors being linked by multi-core optical fibres only.

The OEC transmits light down one core of a multi-core optical fibre cable to the MOC and receives light back from the MOC from the other Cores of the multi-core fibre. The returned light is proportional to the physical parameters measured by the MOC, having been modified by a suitable optical link which varies in direct proportion to these same physical parameters. One such method now to be described is based upon the difference in phase between pulsed light sent from and returned to the OEC.

The OEC pulses light down one core of a multi-core optical fibre cable. The light pulse is not critical regarding exact frequency or intensity, but is critical to maintain the given frequency when set. The OEC received two sets of light pulses back, one each from two further cores of the same multi-core optical fibre cable.

The difference in phase between the two sets of received light pulses is proportional to the physical force being exerted upon the MOC.

The difference in phase is converted to an electrical signal within the standard instrument ranges and used for indication, recording and control as necessary.

The MOC is exposed to the effects of temperature, pressure, differential pressure, proximity, or torque and changes these into physical forces to move one end of a mechanical beam, shaft, or quadrant similar to most standard instrumentation of the bourdon tube, bellows, or torque tube type. The other end of this mechanical link forms a reflective optical-couple between the light pulses received from the OEC and two sets of light pulses sent to the OEC.

Using suitably solid & or flexible materials having similar optical effects, one set of light pulses has a fixed opticalcouple reflected distance no matter what position the beam, shaft or quadrant takes, the other set of light pulses has a varying optical-couple reflected distance proportional to the beam position. This enables a doppler type measurement between the two sets of light pulses sent to the OEC, such a measurement being proportional to the original physical signal accepted by the MOC. Suitable shaping of the optical-couple enables direct square law conversion for flow measurement or similar, with greater accuracy than conventional conversion of the final electrical signal.

The multi-core optical fibre cable linking the OEC and MOC in this example can be any number of cores based upon multiples of three, each group of three is based for one measurement.

WHAT I CLAIM IS: 1. A remote sensing equipment or instrument using a plurality of optical fibres between a sensor and an indicating instrument wherein one fibre is used to transmit light from the indicating instrument to the sensor and means provided at the sensor to modify this light according to physical parameters being sensed by the sensor and to transmit this modified light when an unmodified reference light back through one or more of the remaining fibres to the indicating instrument where means are provided to compare the light sent out to the light received back and the resulting differences represented as the value of the physical proper: experienced by the sensor.

2. An analogue instrument transmitter using sensors as in Claim 1 wherein the light is modified by an optical-couple which is linked to a bourdon tube, diaphragm, bellows or any similar physical parameter device such that the optical path is directly varied by the physical parameter sensed by the device.

3. An analogue transmitter as in Claim 2 wherein the optical link is manufactured from either solid or flexible material.

4. A transmitter as in Claims 2 & 3 wherein both unmodified light and light modified by (54) OPTICAL FIBRE TRANSMISSION INSTRUMENTATION

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. (71) I DENNIS WILLIAM BuRT of British Nationality, of The Bungalow, Woodhouse Lane, Moulton Loosegate, Spalding, Lincs., do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a new range of analogue instrumentation based upon optical fibre instead of electrical cable transmission. Each analogue instrument comprises an optical/ electro convertor (OEC) at the remote indication end and a mechanical/optical convertor (MOC) at the transmitter end, the two convertors being linked by multi-core optical fibres only. The OEC transmits light down one core of a multi-core optical fibre cable to the MOC and receives light back from the MOC from the other Cores of the multi-core fibre. The returned light is proportional to the physical parameters measured by the MOC, having been modified by a suitable optical link which varies in direct proportion to these same physical parameters. One such method now to be described is based upon the difference in phase between pulsed light sent from and returned to the OEC. The OEC pulses light down one core of a multi-core optical fibre cable. The light pulse is not critical regarding exact frequency or intensity, but is critical to maintain the given frequency when set. The OEC received two sets of light pulses back, one each from two further cores of the same multi-core optical fibre cable. The difference in phase between the two sets of received light pulses is proportional to the physical force being exerted upon the MOC. The difference in phase is converted to an electrical signal within the standard instrument ranges and used for indication, recording and control as necessary. The MOC is exposed to the effects of temperature, pressure, differential pressure, proximity, or torque and changes these into physical forces to move one end of a mechanical beam, shaft, or quadrant similar to most standard instrumentation of the bourdon tube, bellows, or torque tube type. The other end of this mechanical link forms a reflective optical-couple between the light pulses received from the OEC and two sets of light pulses sent to the OEC. Using suitably solid & or flexible materials having similar optical effects, one set of light pulses has a fixed opticalcouple reflected distance no matter what position the beam, shaft or quadrant takes, the other set of light pulses has a varying optical-couple reflected distance proportional to the beam position. This enables a doppler type measurement between the two sets of light pulses sent to the OEC, such a measurement being proportional to the original physical signal accepted by the MOC. Suitable shaping of the optical-couple enables direct square law conversion for flow measurement or similar, with greater accuracy than conventional conversion of the final electrical signal. The multi-core optical fibre cable linking the OEC and MOC in this example can be any number of cores based upon multiples of three, each group of three is based for one measurement. WHAT I CLAIM IS:

1. A remote sensing equipment or instrument using a plurality of optical fibres between a sensor and an indicating instrument wherein one fibre is used to transmit light from the indicating instrument to the sensor and means provided at the sensor to modify this light according to physical parameters being sensed by the sensor and to transmit this modified light when an unmodified reference light back through one or more of the remaining fibres to the indicating instrument where means are provided to compare the light sent out to the light received back and the resulting differences represented as the value of the physical proper: experienced by the sensor.

4. A transmitter as in Claims 2 & 3 wherein both unmodified light and light modified by (54) OPTICAL FIBRE TRANSMISSION INSTRUMENTATION the sensed physical parameters is returned to the instrument indicator.

5. An instrumentation indicator based upon Claims 1,2,3 & 4 where light of known value is sent through one optical fibre to a sensor and returned from the sensor in modified and unmodified form being respectively the original value and the transmitter reference, this difference then being indicated as the value of the physical parameter sensed by the sensor.

6. An instrument as in Claims 1,2, 3 & 4 wherein pulsed light is sent through one optical fibre to the sensor and returned through one or more of the other fibres for phase comparison.

7. An instrument indicator based upon Claims 1, 2, 3,4 & 6 wherein the difference in phase between the sent and received pulses is indicated as the value of the physical parameter sensed by the transmitter.

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