JPS61155833A - Detecting device for abnormality of optical fiber - Google Patents

Abstract

PURPOSE:To detect the abnormality of an optical fiber securely by detecting the output of a laser oscillator and the intensity of laser beam passed through the optical fiber, operating their ratio, and comparing it to the value in normal operation. CONSTITUTION:Part of laser beam emitted by oscillation 11 is transmitted 12 and photodetected by the 1st detector 13 to detect an electric output I0, which is inputted to a signal processing part 14. Further, laser beam after reflection 12 is converged 15 and passed through the optical fiber 6 to form an image through a lens 17. Laser beam reflected by the surface of the lens 17 is photodetected by the 2nd detector 18, which detects its intensity Ir. When this intensity Ir is inputted to the signal processing part 14, the processing part 14 operates a=Ir/I0. This ratio (a) is compared with the value in normal operation and when the ratio (a) is much larger than the value in normal operation, it is judged that the optical fiber 16 is abnormal, so that a signal for stopping the laser oscillation is outputted to a laser controller 19.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an optical fiber abnormality detection device for detecting an abnormality in an optical fiber that is transmitting laser light. [Technical Background of the Invention and Problems thereof] Laser light is It is used for industrial and medical purposes, but if an abnormality occurs in the optical fiber that transmits this laser light, it is necessary to detect this and immediately shut down the power to the laser oscillation device that oscillates the laser light to prevent danger. be. By the way, as a technique for detecting abnormalities in the optical fiber, there is a technique disclosed in Japanese Patent Laid-Open No. 59-9778.

As shown in FIG. 3, a laser beam 2 oscillated from a laser oscillation device 1 is condensed by a condensing lens 3, and is incident on an optical fiber 4Vc.

In order to detect an abnormality in the optical fiber 4 in a device in which the laser beam 2 emitted from the output end of the optical fiber 4 is focused by the imaging lens 5 and irradiated onto the irradiated object 6,
A light receiving element 7 having a through hole in the center is provided in front of the incident side of the optical fiber 4, and a control section 8 is provided connected to the light receiving element 7. Then, the optical fiber 4
The light receiving element 7 receives only the reflected light 9 from the inside and the output end of the light receiving element 7, and the output of the light receiving element 7 is constantly monitored by the control unit 8, and if there is an abnormality, the oscillation of the Rade oscillator 1 is stopped. ing.

In this way, according to the above publication, the optical fiber 4
Since the comparison is based on the reflected light 9 returning from the output end of the optical fiber 4, there is a drawback that it is difficult to detect an abnormality when the optical fiber 4 is clearly broken as shown in FIG.

[Purpose of the invention]

This invention was made in consideration of the above circumstances, and it is possible to reliably detect an abnormality under any condition when an optical fiber is broken, and also to detect the abnormality even if oscillation stops due to an abnormality in the radar oscillator. It is an object of the present invention to provide an optical fiber abnormality detection device that can detect abnormalities in optical fibers.

[Summary of the invention]

In order to achieve the above object, the present invention detects a laser beam emitted from a laser oscillator using a first detector, and also detects the laser beam emitted from the laser oscillator after passing through an optical fiber. The intensity of the reflected laser light is detected by a second detector, which is reflected by the surface of an imaging lens provided on the output side of the fiber, and the electrical signals from these detectors are input to a control circuit and compared. The laser oscillator is configured to detect the presence or absence of the laser oscillator and stop the laser oscillator.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the accompanying drawings. 11 in Figure 1 is a laser oscillator, and this laser oscillator 1
A semi-transparent reflective plate 12 is provided in front of the mirror 1 in an inclined manner. This semi-transparent reflecting plate 12 is configured to allow the laser beam oscillated by the laser oscillator 11 to pass straight through and reflect it on its surface. A first detector 13 is provided in front of the translucent reflector 12. The first detector 13 is electrically connected to a signal processing section 14. Further, a condensing lens 15 is provided in the optical path of the laser beam reflected by the semi-transparent reflecting plate 12. An optical fiber 16 is provided on the output side of this condensing lens 15, and an imaging lens 17 is provided on the output side of this optical fiber I6. The LED light transmitted through the imaging lens 17 is used for industrial, medical, etc. purposes. Further, a second detector 18 is provided that receives the laser light reflected on the surface of the imaging lens 170 and detects its intensity.

This second detector 18 is electrically connected to the signal processing section 14 . A laser control device 19 is electrically connected to this signal processing section 14.
4 and the laser control device 19 constitute a control circuit 20.

When the radar device equipped with the optical fiber abnormality detection device configured as described above is operated, a part of the laser beam emitted from the laser oscillator 11 passes through the semi-transparent reflecting mirror 12 and then passes through the first detector. 13 and electrical output I0
is detected and this output! . is input to the signal processing section 14.

Further, the laser beam reflected by the semi-transparent reflecting mirror 12 is condensed by a condensing lens 15 and passes through an optical fiber 16. The radar light emitted from the output end of the optical fiber 16 is imaged by an imaging lens 17 and is used for industrial or medical purposes. Further, the laser beam reflected on the surface of the imaging lens 17 is received by the second detector 18, and its intensity Ir is detected. When this intensity Ir is input to the signal processing unit 14, the signal processing unit 14 calculates the ratio a 9 Ir/I of the above I. Calculate. This a is compared with the normal value, and if the calculated value of a is one degree larger than the normal value, it is assumed that an abnormality has occurred in the optical fiber 16, and a signal to stop laser oscillation is sent to the laser. It is output to the control device 19. For example, if the optical fiber 16 is damaged, the power of the radar light transmitted by the optical fiber 16 will decrease, so the calculated value of a will be smaller than the normal value, so it will be determined as abnormal, and the signal processing unit 14 sends a signal to the laser control device 19 to stop the laser oscillator 11.

Note that in the above embodiment, a value corresponding to the laser power is used to detect an abnormality, but the present invention is not limited to this, and integrating circuits are added to each of the first and second detectors 13 and 18, A value corresponding to energy may be measured and used.Furthermore, the above-mentioned No. 1. The signal may be transmitted from the second detector 13.degree. 18 to the signal processing section 14 by a method of transmitting an analog signal or a method of transmitting it in the form of a digital signal.

Next, we will introduce a second model in which the same components in Fig. 1 are given the same symbols.
The figure shows another embodiment of the invention, in which the first and second detectors 13. The IBs are each incorporated into the signal processing unit 14, and the laser beam oscillated from the laser oscillator 11 is passed through the condensing lens 2 through the optical fiber 22, and the laser beam reflected from the imaging lens 17 is transmitted through the condensing lens 23. The first signal of the signal processing section 14 is connected to the optical fiber 24 via the optical fiber 24. Second
The data is transmitted to the detectors 13 and 18 of .

〔Effect of the invention〕

As explained above, in this invention, in a laser device or the like, when a laser beam is transmitted using an optical fiber, the output of the laser oscillator and the laser beam passing through the optical fiber are used to detect an abnormality in the optical fiber. We decided to detect an abnormality by detecting the intensity of the light, calculating the value of these ratios, and comparing it with the normal value. It not only detects abnormalities, but also prevents abnormalities in the output of the laser oscillator from being detected as abnormalities in the optical fiber.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing one embodiment of the present invention, Fig. 2 is a block diagram showing another embodiment of the invention, Fig. 3 is a block diagram showing a conventional device, and Fig. 4 is a line optical fiber. 011...Laser oscillator, 13...
First detector, 16... Optical 7-eyeper, 17... Imaging lens, 18... Second detector, 20... Control circuit. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 C-5 2=G6

Claims (1)

[Claims] a first detector that detects the output of the laser oscillator; an imaging lens that transmits the laser beam oscillated by the laser oscillator through an optical fiber and forms an image; and a laser beam that is reflected at the incident surface of the imaging lens. and a control circuit that stops the laser oscillator when an abnormality is detected based on the electrical signals from the first detector and the second detector. Optical fiber anomaly detection device.