Fluid coupled fiber optic sensor

• US 4,928,006 A
• Filed: 04/13/1989
• Issued: 05/22/1990
• Est. Priority Date: 03/13/1987
• Status: Expired due to Fees

• Current Assignee: Kershaw, Charles H.
• Original Assignee: Kershaw, Charles H.
• Inventors: Kershaw, Charles H.
• Primary Examiner(s): Nelms, David C.
• Application Number:
  US07/337,965
• Time in Patent Office: 404 Days
• Field of Search: 250/231 R, 250/227, 350/96.1
• US Class Current: 250/201.1
• CPC Class Codes: G01D 5/268 using optical fibres G01D5/28 - G01D5/38 take precedence
• CPC Class Codes: G01F 23/292 Light , e.g. infrared or ultraviolet
• CPC Class Codes: G01F 23/2922 with light-conducting sensing elements, e.g. prisms
• CPC Class Codes: G02B 6/2817 using reflective elements to split or combine optical signals
• CPC Class Codes: G02B 6/2821 using lateral coupling between contiguous fibres to split or combine optical signals
• CPC Class Codes: G02B 6/2852 using tapping light guides arranged sidewardly, e.g. in a non-parallel relationship with respect to the bus light guides (light extraction or launching through cladding, with or without surface discontinuities, bent structures)

Abstract

A passive transducer apparatus and method of use for producing a useful output light signal in response to a sensed condition. The sensed condition varies the light emitted from a first fiber optic light conductor that is apparently captured or detected by a second fiber optic light conductor. The light captured by the second or collector fiber optic member is the useful output signal which may be made proportional to the sensed condition. The apparent change in light capture may be caused by a relative change in geometry of the fiber optic members, by variation in the coupling fluid or by an external optical member.

Claims

1. A method of using a transducer to determine a sensed condition, including the steps of:

transmitting a light signal through a first fiber optic conductor;

emitting at least a portion of the light signal from a side window means in a first fiber optic conductor to contact a light reflective surface means;

coupling optically the first and second fiber optic conductors with a preselected fluid medium;

capturing at least a portion of the emitted light signal from the first fiber optic contacting said light reflective surface with a second fiber optic conductor;

transmitting the light signal captured by the second fiber optic conductor through the second fiber optic conductor;

sensing a value for the light signal conducted through the second fiber optic conductor; and

determining the condition sensed by comparing the sensed value for the light signal conducted through the second fiber optic conductor with a reference value;

changing the relative position of an external the light reflective surface means in response to the sensed condition to proportionally control the captured portion of the emitted light signal.

2. A method of using a transducer to determine a sensed condition, including the steps of:

transmitting a light signal through a first light conductor;

emitting at least a portion of the light signal from the first light conductor to contact a light-reflective surface means;

capturing at least a portion of the emitted light signal from the first light conductor contacting the external surface of the optical member with a side window mans of a second light conductor;

transmitting the light signal captured by the second light conductor through the second light conductor;

sensing a value for the light signal conducted through the fiber optic conductor; and

determining the condition sensed by comparing the sensed value for the light signal conducted through the second light conductor with a reference value;

coupling optically the first and second light conductors with a preselected fluid medium; and

changing the relative position of the light reflective surface means in response to the sensed condition to proportionally control the captured portion of the emitted light signal.

3. A transducer apparatus for producing a useful output light signal in response to a sensed condition, including:

a housing adapted for placement in operable communication with the condition to be sensed and having first and second fiber optic members operably mounted therewith;

means for optically connecting said first fiber optic member with a source of light;

means for optically connecting said second fiber optic member with an appropriate light sensor;

said first fiber optic member having a side windows means for emitting a predetermined light pattern;

said second fiber optic member having means for capturing at least a portion of the light emitted from the first fiber optic member for transmitting to the light sensor; and

means for varying the light collected by the second fiber optic member in response to the sensed conditions being transduced to provide a useful output signal;

said housing forming a chamber for receiving a coupling fluid having a preselected index of refraction for directing the emitted light in a desired path for capture by said second fiber optic member;

said means for varying provides a proportional change in the light collected by said second fiber optic member in response to a change in the sensed condition to provide a useful range of output signals; and

said means for varying including light directional control means mounted with said housing and operably disposed in the emitted light path between said first and second fiber optic members for moving in response to the sensed condition to vary the emitted light collected by said second fiber optic member.

4. A transducer apparatus for producing a useful output light signal in response to a sensed condition, including:

a housing adapted for placement in operable communication with the condition to be sensed and having first and second light conductor members operably mounted therewith;

means for optically connecting said first light conductor member with a source of light;

means for optically connecting said second light conductor member with an appropriate light sensor;

said first light conductor member having means for emitting a predetermined light pattern;

said second light conductor member having a side window means for capturing at least a portion of the light emitted from the first conductor member for transmitting to the light sensor; and

means for varying the light collected by the second light conductor member in response to the sensed conditions being transduced to provide a useful output signal;

said housing forming a chamber for receiving a coupling fluid having a preselected index of refraction for directing the emitted light in a desired path for capture by said second light conductor member;

said means for varying provides a proportional change in the light collected by said second light conductor member in response to a change in the sensed condition to provide a useful range of output signals; and

said means for varying including light directional control means mounted with said housing and operably disposed in the emitted light path between said first and second fiber optic members for moving in response to the sensed condition to vary the emitted light collected by said second light conductor member.

5. A light coupler, including:

a first dielectric waveguide for emitting a light signal, said first dielectric having a means for emitting the light signal in a predetermined path;

a second dielectric waveguide having side window means for receiving the light signal emitted by said first dielectric waveguide, said second dielectric waveguide having a side window for receiving the light signal;

a coupling fluid of preselected refractive index for optically coupling said first dielectric waveguide with said second dielectric waveguide; and

means, disposed in the path of the light signal emitted from said first dielectric waveguide, for controlling the light path direction between said first and second dielectric waveguides in response to a sensed condition by changing the position of said means for controlling the light path direction between said first and second dielectric waveguides to control the emitted light collected by said second waveguide.

6. The light coupler of claim 5, wherein:

said first and second dielectric waveguides are operably fixed relative to each other.

7. The light coupler of claim 5, wherein:

said first and said second dielectric waveguides are operably movable relative to each other.

8. A light coupler, including:

a first dielectric waveguide for emitting a light signal, said first dielectric having a side window means for emitting the light signal in a predetermined path;

a second dielectric waveguide having means for receiving the light signal emitted by said first dielectric waveguide;

a coupling fluid of preselected refractive index for optically coupling said first dielectric waveguide with said second dielectric waveguide; and

means, disposed in the path of the light signal emitted from said first dielectric waveguide, for controlling the light path direction between said first and second dielectric waveguides in response to a sensed condition by changing the position of said means for controlling the light path direction between said first and second dielectric waveguide to control the emitted light collected by said second waveguide.

9. The light coupler of claim 8, wherein:

said first and said second dielectric waveguides are operably fixed relative to each other.

10. The light coupler of claim 8, wherein:

said first and said second dielectric waveguides are operably movable relative to each other.