JPH0572533B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for detecting a break in a fiber for optical power transmission used in a laser scalpel, a laser processing device, etc.

[Conventional technology and problems]

When transmitting power by fiber,
Care must be taken to avoid accidents due to fiber breakage.

For this reason, as a method for detecting disconnection, for example, Japanese Patent Application Laid-Open No. 56-12062 (fiber for energy transmission)
and Japanese Utility Model Application No. 57-69211 (Energy fiber with fusing detection line) have been proposed.

However, in the above devices, a part of the electric circuit extends to the end of the fiber transmission line, so it is not suitable for cases where electrical insulation is particularly required, such as in medical equipment such as laser scalpels and certain processing equipment. , it is necessary to take special insulation measures for termination processing. this is,
This is contrary to the insulating property which is the advantage of fiber.

[Structure of the invention]

The present invention solves the problems of the prior art described above by providing a method for detecting fiber breakage using light.
The basic system is shown in FIG. 1, and the configuration of the present invention will be explained.

In FIG. 1A, a plastic fiber 3 which is bent and folded back near the output end of the power transmission fiber is placed along the power transmission fiber 2 of the power beam 1. plastic fiber 3
Reference light 4 is incident on one end of the power transmission fiber, and output light 6 that is turned back near the output end (terminal end) of the power transmission fiber is received by a detector 7 .

Under normal conditions, it is as shown in Figure 1A above, but if the adjacent power transmission fiber 1 breaks as shown in Figure 1B, the temperature near the welded part 8 will drop several times.
The temperature reaches 100°C or higher, melting the plastic fiber 3 with a low melting point (100 to 100 degrees). Therefore, as shown in FIG. 1B, the emitted light 6 (see FIG. 1B) disappears and is no longer received by the detector 7. That is, a break in the power transmission fiber 2 can be detected by a change in the output of the detector 7.

However, the plastic fiber 3 is not limited to one fiber strand, but may be a bundle of several fibers.

Based on the basic method shown in Figure 1 A and B, the second
The best embodiment of the present invention will be explained with reference to the drawings.

In FIG. 2, a visible laser beam such as a He--Ne laser beam is used as the reference beam 4. The reason for this is that the CO ₂ laser or YAG laser used as power beam 1 is infrared light and is invisible to the human eye, so visible laser light such as a He-Ne laser is often used as a guide light. This is because branching out and using them is advantageous in terms of cost reduction and device miniaturization. In addition, visible laser light can be seen visually, which is convenient for adjustment and maintenance.

In order to make the reference light 4 enter the plastic fiber 3 well, it is better to focus it into a small spot using a lens 13 as shown in the figure.

This lens 13 can have a transmittance close to 100% by applying a non-reflection coating (not shown). Similarly, if the input end of the plastic fiber 3 is also coated with an anti-reflection coating, noise components due to reflection from the lens 13 and the input end of the fiber can be eliminated.

Although the detector 7 is not particularly selected, when a disconnection is detected by its output, it is necessary to immediately shut off the laser power source 14 or take other measures. Therefore, the comparison circuit 15, the disconnection detection signal 16,
A control circuit 17 and an alarm circuit 18 for the laser power source 14 are arranged, and a buzzer 19, a lamp 20, and other alarm devices 21 are arranged as shown.

〔Effect of the invention〕

The present invention has the following effects as described above.

A break in the power transmission fiber is detected by a change in the light emitted from the plastic fiber by means of a detector or the like, and a complete safety measure is taken.

[Brief explanation of the drawing]

FIG. 1 relates to the basic system of the present invention, in which A is an explanatory diagram of a normal state, B is an explanatory diagram of a power transmission fiber disconnected state, and FIG. 2 is an explanatory diagram of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Power beam, 2...Power transmission fiber, 3...Plastic fiber, 4...Reference light, 6...Emission light, 7...Detector, 8...Fusing section, 13...Lens, 14... ...Laser power supply, 1
5...Comparison circuit, 16...Disconnection detection signal, 17...
...Laser power supply control circuit, 18...Alarm circuit, 19
...Buzzer, 20...Lamp, 21...Other alarms.

Claims (1)

[Claims] 1. Along a power transmission fiber that transmits infrared light and irradiates the target object, a plastic fiber that is folded back near the output end of the power transmission fiber is arranged, and one end of the plastic fiber is arranged. In a power transmission fiber break detection method, a break in the power transmission fiber is detected by introducing a reference light into the plastic fiber and measuring the loss of the reference light inside the plastic fiber. A disconnection detection method for power transmission fibers, which is characterized by branching a visible laser beam provided for verification and introducing it into a plastic fiber.