JPS61212809A - Optical coupler - Google Patents

Abstract

PURPOSE:To transmit light efficiently by putting the incidence end surface of an optical fiber closely to the secondary focus on a light source side where light is converged and forming a curved concave part like a spherical surface in the incidence end surface so that incident light from the secondary focus is below an angle of total reflection. CONSTITUTION:A reflection mirror which has a curved reflecting surface 5 for converging light from a light emission part 2 on the secondary focus 4 is provided at the periphery of a lamp 1. An optical fiber 8 formed by bundling many optical fiberous transmitters 6 with a converging body 7 whose end side is opened is provided, and a spherical or elliptic concave part 10 is formed in the converging end surface of the fiber 8; and transparent resin 11 is provided integrally outside the converging end surface 9, its incidence end surface 12 is provided nearby the secondary focus 4, and a spherical or elliptic concave part 13 is formed in the incidence end surface 12. The shape is so determined that the light from the secondary focus 4 is at <=30 deg. over the entire surface of the concave part 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical coupling device for transmitting light to an arbitrary position via an optical fiber.

2. Description of the Related Art Conventionally, when transmitting light to an arbitrary location using an optical fiber, the light is focused on the end face of the optical fiber and then enters the optical fiber. The input end face of this optical fiber is polished to a flat surface in order to improve the input efficiency.

Problems to be Solved by the Invention It is impossible to focus the light from a light source into a point due to the shape of the light emitting part of the light source, the shape of the reflecting mirror, etc. That is, although there are various shapes of the focal point, for example, there is one in which the focal point is formed in a range having a certain length along the optical axis.

For a focal point of such a shape, if the input end face of the optical fiber is flat as described above, the angle of incidence of the incident light on the input end face will exceed the angle of total reflection, and the light will be reflected at this part. The amount of light that is not transmitted is considerable, and effective transmission cannot be performed.

Means for Solving the Problems A curved concave portion of a spherical or elliptical surface is formed on the end face of an optical fiber so that the angle of incidence from the secondary focal point is equal to or less than the angle of total reflection.

Effect -2 = As a result, the secondary focus of the light on the light source side is linear.
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゛" - Example A first example of the present invention will be explained based on FIG. 1. First, a lamp 1 as a light source is provided.

This lamp 1 is provided with a light emitting section 2 that serves as a primary focus. This light emitting part 2 is made of a filament and necessarily has a certain size.

That is, it has a certain width and a constant length in the optical axis direction. ·Also,
A reflecting mirror 3 is provided around the lamp 1.

This reflecting mirror 3 has a curved reflecting surface 5 that focuses the light emitted from the light emitting section 2 onto a secondary focal point 4.

Next, an optical fiber 8 is provided in which a large number of fibrous optical transmission bodies 6 are converged by a converging body 7 whose end side is open, and a concave portion 10 formed by a spherical or ellipsoidal curved surface is formed on the converging end surface 9 of the optical fiber 8. A transparent resin 11 made of acrylic resin or the like is integrally provided on the outside of this converging end surface 9, and an incident end surface 12 of this transparent resin 11 is connected to the secondary focal point 4.
is located close to. A spherical or elliptical recess 13 is formed in the input end face 12 of the optical fiber 8 . This concave portion 13 is set so that the incident angle of light from the secondary focal point 4 does not exceed the total reflection angle at each portion. For example, the shape of the concave portion 13 is determined so that the light from the secondary focal point 4 is 30° or less over the entire surface of the concave portion 13 .

Further, since the end portion side of the converging body 7 has a widening opening, the amount of incident light that escapes is reduced, and the light can be used effectively.

The recess 13 is formed in a spherical or ellipsoidal shape, but since it is symmetrical about the optical axis, its surface can be easily polished by machining.

Therefore, in actual implementation, the concave part in the convergent end surface 9 of the optical transmitter 6]-- can be omitted if total reflection does not occur at the boundary between the transparent resin 11 and the optical transmitter 6. It is.

In such a configuration, when the lamp 1 is turned on, the light from the light emitting section 2 is reflected by the reflection surface 5 of the reflection mirror 3 and is focused on the secondary focal point 4. This secondary focal point 4 has a force having a certain length in the optical axis direction (the light that has passed through any part is incident on the concave part 13 of the incident end face 12 of the optical fiber 8 with an incident angle less than the total reflection angle). Therefore, the light is transmitted into the optical fiber 8 without being reflected at the input end face 12 of the optical fiber 8, and the amount of light does not decrease.

Next, a second embodiment of the present invention will be described based on FIG. The same parts as in the previous embodiment are designated by the same reference numerals, and the description thereof will be omitted (the same applies hereinafter). First, in this embodiment, the optical fiber 8
This is the case in which the transparent resin 11 is not provided at the end of the lens, and the recess 10 coincides with the recess 13 of the incident end surface 12.

Next, a third embodiment of the present invention will be explained based on FIG. In this embodiment, a color screen 14 is disposed between the reflecting mirror 3 and the secondary focal point 4. This color screen 14 is attached to a rotary plate 16 supported by a rotating shaft 15, and a plurality of screens of different colors may be attached. This makes it extremely easy to separate and transmit light of a desired fixed wavelength.

Furthermore, by positioning the color screen 14 close to the secondary focal point 4 or by making the shape of the reflecting mirror 5 elliptical, the light transmission area of the color screen 14 can be reduced.

In the above embodiment, the lamp 1 such as a mercury lamp was used as the light source. However, in actual practice, sunlight is focused by a Fresnel lens, and the focused light is applied to the end face of the optical fiber 8. It may also be used in a device that makes the light incident and guides it to an arbitrary position.

Effects of the Invention As described above, the present invention is a system in which light from the light source side enters from the incident end face of an optical fiber and is transmitted to a required position, in which light from the secondary focal point of the light is transmitted to the incident end face of the optical fiber. Since the curved concave part is formed on a spherical or ellipsoidal surface so that the incident angle is less than the total reflection angle - tsuba - it is possible to reduce loss due to light reflection at the input end face of the optical fiber, resulting in extremely efficient light generation. It has advantages such as being able to perform transmission and making it easy to manufacture curved recesses.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional side view showing the first embodiment of the present invention, and FIG.
The figure is a longitudinal side view showing a second embodiment of the invention, and FIG. 3 is a longitudinal side view showing a third embodiment of the invention. 1...Lamp (light source), 4...Secondary focal point, 6...Light transmission body, 8.Optical fiber, 12...Incidence end surface, 13.
・Concavity

Claims (1)

[Claims] In a device in which light from a light source side is made to enter an incident end face of an optical fiber formed by an optical transmission body, the incident end face of the optical fiber is brought close to a secondary focal point where the light from the light source side is condensed, and this incident end face An optical coupling device characterized in that a curved concave portion is formed on a spherical or ellipsoidal surface so that an incident angle from the secondary focal point is equal to or less than a total reflection angle.