Apparatus and methods relating to fluorescent optical switches

Abstract

A fiber optic switching system which includes an optical switch having a movable actuator and a light fiber coupled to the actuator which terminates at an end target surface thereof for conducting excitation light from a light source to the optical switch mechanism. A flexible film or other surface whose response is conditioned to provide at least two different fluorescent surfaces is positioned such that an end surface of the actuator abuts or is placed in close proximity to the film throughout its movement from one position to another. A detector detects light emitted from the film. The actuator is movable so as to direct excitation light from the light fiber from the one fluorescent surface of the film to another and the detector detects light emitted from the film so as to determine which fluorescent surface of the film from which light has been emitted.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority from U.S. provisional patent application No. 60 / 188,653, filed Mar. 10, 2000.BACKGROUND [0002] The development of optical switches, including fiber optic switches, has been a result of a need to avoid electrical power in certain control lines because electrical switches in such situations can, for example, cause explosions in an explosive atmosphere and shocks if in the presence of liquid. Many optical switches are known in the art. See, e.g., U.S. Pat. No. 3,999,074; U.S. Pat. No. 4,045,667; U.S. Pat. No. 4,315,147; U.S. Pat. No. 4,904,044; U.S. Pat. No. 4,704,656; U.S. Pat. No. 5,892,862; U.S. Pat. No. 5,046,806. [0003] For some optical switches, for example those containing a mirror actuator, the coupling efficiency of the reflected light and, therefore, the effectiveness of the signal detection is sensitive to alignment problems. The mirror actuator mechanism typically locates the mirror surfa...

AI Technical Summary

Benefits of technology

[0014] An advantage of the flexible film abutting the end of the actuator or fiber, or other arrangement wherein the illumination provider abuts the target surface, is the lowered likelihood of misalignment. Because the flexible film conforms to the face of the fiber or actuator, it maintains the parallelism between film and fiber surfaces desirable to enhance high coupling efficiency. And, arranging the end of the fiber to abut the flexible film throughout its range of movement reduces the likelihood of contamination of the area between the fiber and film with fluids or air-borne particulate.

[0021] It is possible to avoid the need for a directional coupler between the light source and the detectors by using a plurality of light fibers in, for example in a bundle, with only some coupled to the light source and others coupled to the detector(s). A gap can be generally provided between the mirror surface and the fibers, so that some off-axis rays can couple from one fiber to the other. Where the illumination fibers and the detection fibers can also contact the target surface, for example where the fluorescent light is detected after a delay, or where the illumination and detection light guides are disposed on opposite sides of the target material or surface and detect transmissive light or other non-reflectance light.

[0022] A dual fiber system can avoid the problems associated with gap contamination and other problems that attenuate the light by providing a transparent layer of selected thickness in front of the fluorescent surface. The flexible film may be transparent and of a selected thickness with a mirror coating on the back so that the film itself provides the requisite spacing without permitting the entry of contamination.

Problems solved by technology

The development of optical switches, including fiber optic switches, has been a result of a need to avoid electrical power in certain control lines because electrical switches in such situations can, for example, cause explosions in an explosive atmosphere and shocks if in the presence of liquid.

For some optical switches, for example those containing a mirror actuator, the coupling efficiency of the reflected light and, therefore, the effectiveness of the signal detection is sensitive to alignment problems.

In systems in which there is a gap between an end of the fiber and the mirror, the surfaces of the fiber and mirror may be prone to contamination, which can lead to each of back scattering and contamination, which in turn can lead to loss of light and hence reduced efficiency.

Back scattering at any of the other optical interfaces can create additional noise in the optical signal and require additional signal processing or detector compensation to accurately detect the state of the switch.

This higher energy level is usually unstable.

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