Optical sensors and optical fibre networks for such sensors
First Claim
1. An optical sensor comprising:
- elongate light transmission means;
lens means of at least substantially half-pitch length, positioned with one of its focal planes substantially at a mouth of the light transmission means to receive and focus a diverging cone of light emergent therefrom;
reflector means substantially at another focal plane of said lens means to reflect said focused light back to said mouth of the light transmission means; and
detection means in the path of said light between said mouth and said reflector means, said detection means being responsive to an external condition to influence said diverging cone of light.
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Accused Products
Abstract
An optical sensor includes elongate light transmission means such as an optical fibre (13). A lens (16) of at least nearly half-pitch length is positioned with one of its focal planes substantially at a mouth (13a) of the optical fibre to receive and focus a diverging cone of light emergent therefrom. A reflector (20) is disposed substantially at another focal plane of the lens to reflect the focused light back to the mouth of the fibre. Detection means (14) in the path of the light between the mouth and the reflector is arranged to influence the light in response to an external condition in a manner whereby the reflected light received back at the fibre mouth may be monitored to detect the influence and thereby the condition. An optical fibre network has an incident fibre (40) and a detection fibre (42) coupled to plural optical components (60) via respective optical fibres (62) associated with the components and one or more optical fibre couplers (64, 68, 69). The network further includes means (44) to transmit along the incident fibre incident signals of close but discrete wavelengths, and means (82) associated with each of said respective optical fibres (62) to reflect a portion of each of the signals back along the fibre as a respective reference signal.
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Citations
24 Claims
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1. An optical sensor comprising:
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elongate light transmission means; lens means of at least substantially half-pitch length, positioned with one of its focal planes substantially at a mouth of the light transmission means to receive and focus a diverging cone of light emergent therefrom; reflector means substantially at another focal plane of said lens means to reflect said focused light back to said mouth of the light transmission means; and detection means in the path of said light between said mouth and said reflector means, said detection means being responsive to an external condition to influence said diverging cone of light. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An optical fibre network comprising:
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an incident fibre and a detection fibre coupled to plural optical components via respective sensor optical fibres associated with the components and at least one optical fibre coupler, said respective sensor optical fibres with varying lengths; means to transmit incident signals along said incident fibre and then via said coupler(s) along said sensor optical fibres to said components; and respective means associated with each of said sensor optical fibres to reflect a portion of each said incident signals back along the respective sensor optical fibres and then said detection fibre as a respective reference signal, said respective reference signal comprising a train of time-separated pulses, each of said pulses corresponding to one of said incident signals, said pulses being analyzed collectively to determine an external condition. - View Dependent Claims (15, 16, 17)
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18. An optical sensor comprising:
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elongate light transmission means; lens means fixed with respect to a mouth of said light transmission means, being positioned with one of its focal planes substantially at said mouth to receive and refract a diverging cone of light emergent therefrom; reflector means fixed with respect to said lens means to reflect said refracted light back to said mouth of the light transmission means; and detection means in the path of said light between said mouth and said reflector means, said detection means being responsive to an external condition to influence said light between said mouth and said reflector means. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification