METHOD OF POSITIONING LIGHT RECEIVING END OF LIGHT CONDUCTOR AT FOCAL POINT OF LENS AND APPARATUS THEREFOR

Abstract: A blue laser beam or a red laser beam or a composite beam thereof is transmitted through a lens into an optical fiber, allowing one to position a light receiving end of the optical fiber at the focal point of the lens observing it by the naked eye. Properly positioned at the lens focal point, the optical fiber is rigidly connected to a support member by an adhesive.

Description: METHOD OF POSITIONING LIGHT RECEIVING END OF LIGHT CONDUCTOR AT FOCAL POINT OF LENS AND APPARATUS THEREFOR BACKGROUND OF THE INVENTION The present invention relates to a system for conducting light from a light source to a desired location for lighting and other applications and, more particularly, to an apparatus applicable to such a system to accurately position a light receiving end of a light conducting element at the focal point of a lens. The applicant has proposed in various forms a solar collector which is constructed to converge the sunlight into a fiber optic cable by means of a lens or the like, so that the light may propagate through the cable to a desired location for lighting, for example. In the prdposed system, the sunlight is converged mainly by Fresnel lenses each having a diameter of about 40 centimeters, and then introduced into fiber optic cables each having a diameter of about one centimeter. The light receiving end of each fiber optic cable is located at the focal point of its associated Fresnel lens. In this construction, the sunlight converged by the lenses propagates through the fiber optic cables to a desired station for an intended application. The light receiving end of each of the above-mentioned fiber optic cables is adjustable in position in the vicinity of the focal point of the Fresnel lens associated therewith along the optical axis of the lens and in a plane perpendicular to the optical axis. This allows the light receiving end of the cable to register with the focal point of the lens. The prior art solar collector uses a plurality of Fresnel lenses each having a diameter of about 40 centimeters. Typically, tne number of lenses is seven, nineteen or thirty-seven. Because the number of lenses is not so large, positioning the cables one by one at the focal points of the lenses is not obJectlonably time- or laborconsuming. however, a fiber optic cable is a bundle of numerous optical fibers which cannot be positioned without developing spaces therebetween. The spaces between the optical fibers reduce the quantity of light allowed into the cable after being converged by the Fresnel lens, constituting a major cause of a decrease in the collection efficiency. Another solar collector proposed by the applicant is elaborated to solve the problem discussed above by using a number of lenses, such as 2,000, dimensioned about 4 centimeters in diameter. Optical fibers, dimensioned about l-0.2mm in diameter, are located such that their light receiving ends are respectively held in register with the focal points of the lenses. Should the light receiving ends of the optical fibers be positioned at the focal points of the lenses in the same manner as in the case with the Fresnel lenses having a diameter of 40 centimeters, the apparatus would suffer from various drawbacks such as an intricate, bulky and heavy construction, an increase in costs, and troublesome work required for positioning and maintenance. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and apparatus for accurately and efficiently positioning the light receiving end of an optical fiber at the focal point of a lens. It is another object of the present invention to provide a generally improved method and apparatus for positioning light receiving end of a light conductor at the focal point of a lens. In one aspect of the present invention, there is privided a method of positioning a light receiving end of a light conducting element at a focal point of a lens, comprising the steps of emitting at least one coherent color light beam to the lens, moving the light receiving end of the light conducting element into register with the focal point of the lens, and rigidly connecting the light conducting element to a support member by means of an adhesive. In another aspect of the present invention, there is provided an apparatus for positioning a light receiving end of a light conducting element at a focal point of a lens, comprising at least one light source for emitting a coherent color light beam, an optical arrangement for transforming the coherent color light beam into a parallel beam, and a support member for rigidly holding the light conducting member after the light conducting member is positioned at the focal point of the lens. In still another aspect of the present invention, there is provided an apparatus for positioning a light receiving end of a light conducting element at a focal point of a lens, comprising a laser for emitting a red beam, a laser for emitting blue beam, two shutters disposed in optical paths extending from the two lasers respectively, a half-mirror for steering the red and blue laser beams to a common optical path leading to the optical arrangement, and an optical arrangement for transforming the color laser beams into parallel beams, whereby the color laser beams output from the optical arrangement is supplied to the lens. The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawing. BRIEF DESCRIPTION OF THE DRAWING Single figure is a schematic view of a preferred embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT While the method for positioning light receiving end of a light conductor at the focal point of a lens and apparatus therefor of the present invention is susceptible of numerous physical embodiments, depending upon the environment and requirements of use, a substantial number of the herein shown and described embodiment have been made, tested and used, and all have performed in an eminently satisfactory manner. Referring to the drawing, a positioning apparatus embodying the present invention is shown and generally designated by the reference numeral 10. The apparatus 10 includes a light source 12 for emitting a coherent color beam such as a red beam. An example of such a light source is a helium-neon laser. The visible color beam from the light source 12 is directed toward a halfmirror 14 while being selectively intercepted by a shutter 16. A second light source 18 emits a coherent light beam of another color such as a blue beam and may comprise an argon laser, for example. The color beam from the light source 18 is also directed toward the half-mirror 14 while being selectively intercepted by a shutter 20. The color beam from the half-mirror 14 is steered to an optical arrangement 22 which serves to transform the incident beam into a parallel beam. Disposed below the optical arrangement 22 is a lens 24 for converging the parallel beam and having a diameter of about 4 centimeters. In practice, a number of such lenses are combined as indicated by phantom lines in the drawing. An optical fiber 26 is located below the lens 24 such that a light receiving end thereof is positioned at the focal point of the lens 24. Again, a number of such optical fibers are arranged in one-to-one correspondence with the lenses 24 as illustrated. The optical fiber 26 is received in an aperture 28 which is formed through a support plate 30 and positioned in register with the optical axis of the overlying lens 24. After the optical fiber 26 has been received in the aperture 28 of the support plate 30 and its light receiving end positioned at the focal point of the lens 24 as will be described, an adhesive 32 is injected from an injector 34 to rigidly connect the optical fiber 26 to the support plate 30. The positioning procedure in accordance with the present invention will be described assuming that the optical fiber 26 is adapted to receive red and and blue light beams selectively. When it is desired to introduce red light into the optical fiber 26, the shutter 20 is so positioned as to interrupt the blue beam from the light source 18, while the shutter 16 is actuated to allow the red beam from the light source 12 to reach the half mirror 14. The red light transmitted through the halfmirror 14 is transformed by the optical arrangement 22 into a parallel beam which is then transmitted through the lens 24. The optical path through which the light beam transmitted through the lens 24 propagates can be observed by the naked eye. Therefore, one is allowed to bring the light receiving end of the optical fiber 26 into register with the focal point of the lens 24 while observing it. This is followed by injecting the adhesive 28 from the injector 34 to securely connect the optical fiber 26 to the support plate 30. Where the desired beam is the blue beam from the second light source 18, the shutter 20 will be opened and the shutter 16 closed. The subsequent procedure is common to the previously described one, that is, the light receiving end of the optical fiber 26 is positioned at the focal point of the lens 24 and then the optical fiber 26 is fixed to the support plate 30. It will be understood that the apparatus 10 is capable of supplying even the daylight by directing both the red beam from the light source 12 and the blue beam from the light source 18 to the lens 24. In summary, it will be seen that the present invention provides a simple method and apparatus which is capable of fixing a light receiving end of an optical fiber at the focal point of a lens. The apparatus is compact and lightweight and needs no maintenance after the assembly. Various modifications will be possible for those skilled in the art after receiving the teachings of the present disclosure without departing from tne scope thereof.

Claims: Patent Claims 1. A method of positioning a light receiving end of a light conducting element at a focal point of a lens, comprising the steps of: emitting at least one coherent color light beam to the lens; moving the light receiving end of the light conducting element to be in register with the focal point of the lens; and regidly connecting the light conducting element to a support member by means of an adhesive. 2. A method as claimed in claim 1, in which the coherent color light beam is a red laser beam. 3. A method as claimed in claim 1, in which the coherent color light beam is a blue laser beam. 4. A method as claimed in claim 1, in which a red laser beam and a blue laser beam are selectively emitted to the lens. 5. An apparatus for positioning a light receiving end of a light conducting element at a focal point of a lens, comprising: at least one light source for emitting a coherent color light beam; an optical arrangement for transforming the coherent color light beam into a parallel beam; and a support member for rigidly holding the light conducting member after the light conducting member is positioned at the focal point of the lens. 6. An apparatus as claimed in claim 5, in which the light source emits a red laser beam. 7. An apparatus as claimed in claim 5, in which the light source emits a blue laser beam. 8. An apparatus as claimed in claim 5, in which a first light source and a second light source selectively emit a red laser beam and a blue laser beam respectively. 9. An apparatus as claimed in claim 8, further comprising a first shutter and a second shutter operatively disposed in optical paths extending from the first and second light sources respectively, and a half-mirror for steering the red and blue laser beams to a common optical path leading to the optical arrangement. 10. An apparatus for positioning a light receiving end of a light conducting element at a focal point of a lens, comprising: a laser for emitting a red beam; a laser for emitting a blue beam; two shutters disposed in optical paths extending from the two lasers respectively; a half-mirror for steering the red and blue laser beams to a common optical path leading to the optical arrangement; and an optical arrangement for transforming the color laser beams into parallel beams; whereby the color laser beams output from the optical arrangement is supplied to the lens.

Inventors: MORI, KEI
Applicants: MORI, KEI
Application year: 1984
Main classification: G02B6
IPC codes: G02B6