JPS63127214A - Optical fiber cable - Google Patents

Abstract

PURPOSE:To prevent a chuck from being heated to transmit the laser light of high output by arranging a condenser lens and an aperture in front of the incidence end of an optical fiber and making the laser light, which passes the aperture, incident on the incidence end of the optical fiber by the condenser lens. CONSTITUTION:In a holder 12, an aperture 10 and a condenser lens 11 are arranged in front of the incidence end of an optical fiber 7. The aperture 10 is pierced by a hole having 0.4mm diameter, and the image of this hole is formed on the incidence end face of the optical fiber 7 by the condenser lens 11. Consequently, the laser light which is condensed by an external condenser lens 14 and is made incident on the aperture 10 passes the aperture 10 and is condensed again by the condenser lens 11 and is made incident on the incidence end of the optical fiber 7. If the laser light has the optical axis misaligned by some cause, it is intercepted by the aperture 10 to prevent a chuck 9 fixing the optical fiber from being heated and the optical fiber from being burned.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical fiber cable for guiding high-power laser light to a predetermined position in a laser processing machine or the like.

2. Description of the Related Art Conventionally, a structure as shown in FIG. 2 has been known as an example of an optical cable for guiding high-output laser light. In the figure, an optical fiber 1 is placed in a protective tube 2, and windows 3 or lenses 4 are attached to both ends to prevent dust, dirt, moisture, etc. from adhering to the end face of the optical fiber and causing damage.

The vicinity of the input end of the optical fiber 1 is fixed by a chuck 6. The laser beam is focused by a condensing lens 6, enters the input end of the optical fiber 1 through the window 3, is then emitted from the output end, and is focused by the lens 4 to a predetermined spot.

Problems to be Solved by the Invention In such a configuration, there will be no problem if the laser beam is accurately incident on the input end of the optical fiber, but sometimes the optical axis may shift for some reason, and in such cases The laser beam is directly irradiated onto the chuck, which heats up the chuck and burns out the optical fiber. Furthermore, even if the incident light is accurate, the reflected light from the end face will be reflected again by the output mirror of the loser oscillator and return with the optical axis shifted, causing problems such as burning out the optical fiber in the same manner as above. Ta. In order to solve this problem, it has been considered to make the core supporter that inserts and holds the core end through an insertion hole into a reflective surface, as seen in, for example, Japanese Patent Application Laid-Open No. 58-183157. At high laser powers, the fiber becomes hot and can melt if it comes into direct contact with the optical fiber.

It is also conceivable to arrange an aperture just in front of the end face of the optical fiber, but there is a problem in that when laser light hits the aperture, diffraction occurs there, and the chuck part is heated by the diffracted light, causing bending damage to the optical fiber.

Means for Solving the Problems The present invention solves the above problems and provides an optical fiber cable capable of transmitting high-power laser light, by arranging a condenser lens and an aperture in front of the input end of one optical fiber. By configuring the aperture so that the image is focused on the input end of the optical fiber by a condensing lens, it is possible to prevent the optical fiber chuck from being heated by the optical axis deviation of the laser beam or the returning light. It is.

The working laser beam is focused by an external condensing lens and is once incident on the aperture. The laser beam that has passed through the aperture is focused again by the condensing lens in the optical cable and enters the input end of the optical fiber. Laser light whose optical axis is misaligned for some reason is blocked by the aperture and does not heat the chuck as in the conventional case.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the vicinity of the input part of the optical fiber cable according to the present invention. Diameter 0.7 made of KH2-6.
It is a 5fl optical fiber. 8 is a thin stainless steel tube that is inserted into this tube. 9 is a chuck for fixing the optical fiber. 1o is an aperture which is a main part of the present invention, and a hole with a diameter Q and 4 mm is bored, and the other parts are mirror-finished.

Reference numeral 11 denotes a condensing lens, which is configured to image a 0.4 mm hole of an aperture onto the input end face of the optical fiber. Reference numeral 12 denotes a holder for locking these apertures, condensing lenses, and chucks in predetermined positions. Further, a part of this holder is provided with an air outlet 13 so that the optical fiber can be cooled.

14 is an external condensing lens provided on the side of the C02 laser oscillator, which directs the CO2 laser beam to the Q of the aperture 4, 411
It narrows down to the M hole. Of course, this can also be installed inside the optical cable. The light that has passed through the aperture 10 is focused onto the input end of the optical fiber 1 by the condenser lens 10 . Laser light incident on the optical fiber cable off the regular optical axis is blocked by the aperture 10, and is not irradiated onto the chuck and heated, as in the conventional case. If the aperture has a mirror surface, it will reflect the laser light and reduce the temperature rise. In addition, the light that hits the edge of the 1° aperture hole causes diffraction and is scattered at a wide angle, but since the aperture hole and the end face of the optical fiber are in an imaging relationship, the light that has been diffracted five times also enters the end face of the optical fiber. be done.

Effects of the Invention As described above, according to the present invention, the condenser lens and the aperture are arranged in front of the optical fiber input end, and the aperture is imaged on the optical fiber input end face by the condenser lens. Even if the laser beam is incident on the optical fiber cable off the normal optical axis, the chuck part of the optical fiber will not be heated, and a high-power laser beam can be guided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the vicinity of the input part of an optical fiber cable according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a conventional optical fiber cable. 7...Optical fiber, 10...Aperture, 11...Condensing lens.

Claims (2)

[Claims] (1) An optical fiber cable comprising: a condenser lens and an aperture arranged in front of an input end of the optical fiber; and an image of the aperture is formed on the input end of the optical fiber by the condenser lens. (2) The optical fiber cable according to claim 1, wherein the surface of the aperture is mirror-finished.