WO2007015467A1

WO2007015467A1 - Method and device for detecting fracture or clogging of optical fiber

Info

Publication number: WO2007015467A1
Application number: PCT/JP2006/315170
Authority: WO
Inventors: Shuichi Sakamoto
Original assignee: Niigata University
Priority date: 2005-08-01
Filing date: 2006-07-31
Publication date: 2007-02-08
Also published as: JPWO2007015467A1; JP4719894B2

Abstract

Fracture or clogging of a hollow optical fiber is detected without damaging the degree of freedom of the hollow optical fiber. A carbon dioxide gas laser generator (5) is connected with the inlet or the primary side of a hollow optical fiber (1) having an outlet or a secondary side connected with a hand piece (6). The carbon dioxide gas laser generator (5) is connected with a loud speaker (7) which is connected with an oscillator (8). In the hand piece (6), the hollow optical fiber (1) is connected with a secondary side microphone (9). When a hole is opened in the middle of the hollow optical fiber (1) or when the hollow optical fiber (1) is broken, acoustic power leaks from the hole in a defect portion and acoustic power transmitted to the secondary side microphone (9) attenuates extremely, therefore abnormality can be checked by means of the secondary side microphone (9).

Description

Specification

Method and apparatus for detecting loss or clogging of optical fiber

Technical field

[0001] The present invention relates to a method and an apparatus for detecting a loss or clogging of an optical fiber.

Background art

[0002] A carbon dioxide laser (CO laser) with a wavelength in the infrared region is used for laser treatment.

2

Such laser treatment devices are known. In such a laser treatment apparatus, light is guided to the handpiece through the laser light source power light guide optical system.

[0003] Hollow optical fibers are excellent in condensing characteristics with a small beam divergence angle, and can transmit lasers in the infrared wavelength region, and are excellent as, for example, medical laser transmission systems. This is because, in surgery, dermatology or dentistry, there are advantages such as less bleeding, faster healing, shorter operation time, and wider range of applicable patients. Carbon dioxide laser treatment is one of the laser surgical devices. A carbon dioxide laser surgical device is known as an instrument.

[0004] In a conventional carbon dioxide laser treatment device, light is transmitted by reflection using an articulated arm equipped with a plurality of optical mirrors. This method has a problem of high cost due to optical mirrors and precise multi-joint arms, and handling of the operator due to the presence of the arm.

In order to solve these problems, an optical fiber soundness inspection device, an optical fiber breakage detection method, and a method of transmitting a carbon dioxide laser in a hollow optical fiber whose inner surface is a mirror surface, such as a medical optical cable, are known. Speak (for example, Patent Documents 1 to 3).

Patent Document 1: Japanese Patent Laid-Open No. 2000-221108

Patent Document 2: JP-A-6-300664

Patent Document 3: Japanese Patent Laid-Open No. 7-284539

Disclosure of the invention

Problems to be solved by the invention [0006] In the case where the hollow optical fiber is used for a light guide optical system, when a defect occurs on the mirror surface of the hollow optical fiber, a carbon dioxide laser melts the glass to open a hole and open an unexpected part. Risk of burning. This danger is also present when the hollow optical fiber is broken.

[0007] By installing an optical system at the exit of the hollow optical fiber as a means for solving such problems, a method for monitoring the laser output can be considered. This method has the greatest advantage of using the hollow optical fiber. There is a problem that the handling property, that is, the degree of freedom of operation is impaired, and the cost increase due to the increase in the number of optical system components may also be a problem.

[0008] Further, even if the hollow optical fiber does not have a hole, the hollow optical fiber becomes unhealthy when melted and clogged at the fiber melting stage.

[0009] A problem to be solved is that a hollow optical fiber used for detecting perforation, breakage, or clogging of a hollow optical fiber in a carbon dioxide laser treatment device of a type that transmits carbon dioxide laser light using a hollow optical fiber. In the method and apparatus for detecting defects in a hollow optical fiber, the defect or clogging of the hollow optical fiber is detected without impairing the degree of freedom of the hollow optical fiber.

Means for solving the problem

[0010] Claim 1 of the present invention is a method of transmitting laser light using a hollow optical fiber, wherein a sound wave is incident from a primary side of the hollow optical fiber and the sound wave is detected from a secondary side. In this method, the hollow optical fiber is detected for defects or clogging.

[0011] According to a second aspect of the present invention, in the method of transmitting laser light using a hollow optical fiber, a sound wave is incident from the primary side of the hollow optical fiber and the sound wave is detected from the secondary side, In this method, the primary side acoustic wave and the secondary side acoustic wave are compared to detect a defect or clogging of the hollow optical fiber.

[0012] Claim 3 of the present invention is characterized in that the primary side sound wave and the secondary side sound wave signal are electrically detected. This method detects defects in optical fibers.

[0013] Claim 4 of the present invention is as described in any one of claims 1 to 3, wherein the sound wave is generated by a speaker and the secondary side sound wave is detected by a microphone. Light This is a method for detecting the loss or clogging of Aiba.

[0014] Claim 5 of the present invention is characterized in that the primary side acoustic wave has a low frequency of 1kHz or less, and the force of any one of claims 1 to 4 is detected. It is a method to do.

[0015] Claim 6 of the present invention is characterized in that the primary side sound wave has a plurality of frequencies, and the method for detecting a loss or clogging of an optical fiber according to any one of claims 1 to 5. It is.

[0016] Claim 7 of the present invention is a hollow light characterized in that a sound source for making a sound wave incident on the primary side of the hollow optical fiber is provided, and a detecting means for detecting the sound wave is provided on the secondary side. This is a fiber loss and clogging detection device.

[0017] According to Claim 8 of the present invention, a hollow optical fiber according to Claim 7, wherein a speaker is connected to the gas laser generator, and a secondary microphone is connected to the hollow optical fiber. This is a device for detecting missing or clogged bars.

[0018] Claim 9 of the present invention is the hollow optical fiber defect or clogging detection device according to claim 8, wherein the hollow optical fiber 1 is provided with a primary microphone.

[0019] The tenth aspect of the present invention is the hollow according to any one of the seventh to ninth aspects, wherein the secondary side is a handpiece side that is connected to a hollow optical fiber and emits laser light. This is an optical fiber defect detection device.

The invention's effect

[0020] In the first aspect of the invention, in the method of detecting perforation or breakage of the hollow optical fiber using sound, a sound wave is incident from the primary side of the optical fiber, and the sound wave is detected from the secondary side. To do. If the hollow optical fiber is perforated, bent, or clogged, the propagation state of the sound wave in the hollow optical fiber changes, and this detects the perforation, breakage, or clogging of the hollow optical fiber. Therefore, an expensive optical system on the secondary side of the hollow optical fiber is not necessary, and the handling ability of the operator is not impaired.

[0021] According to the invention of claim 2, it is possible to detect the loss or clogging of the optical fiber by measuring the primary side sound wave and the secondary side sound wave and measuring the gain.

[0022] In the invention of claim 3, it is possible to detect a defect or clogging with a voltmeter or the like.

In the invention of claim 4, the sound wave is generated by a speaker, and the secondary side sound wave is By detecting by iku, it can be manufactured relatively inexpensively.

[0024] In the invention of claim 5, even if the hollow optical fiber has a hollow inner diameter that is thin, such a hollow portion can function as a low-pass filter with respect to the sound frequency. Can pass through.

[0025] In the invention of claim 6, the reliability of measurement can be increased by monitoring using a plurality of frequencies other than only one frequency.

[0026] According to the invention of claim 7, a change in the propagation state of the sound wave in the hollow optical fiber is detected by making a sound wave incident from the primary side of the hollow optical fiber and detecting the sound wave from the secondary side. Thus, it is possible to detect perforation, breakage or clogging of the hollow optical fiber.

[0027] In the invention of claim 8, a sound wave is incident from the primary side of the hollow optical fiber by a speaker, and the sound wave is detected from the secondary side by a secondary microphone.

[0028] Thus, in the invention of claim 9, the detection of the primary side microphone and the detection of the secondary side microphone can be compared to detect perforation, breakage or clogging of the hollow optical fiber.

In the invention of claim 10, the sound wave passes through the hollow portion of the optical fiber and exits from the outlet of the handpiece 6.

BEST MODE FOR CARRYING OUT THE INVENTION

[0030] Preferred embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below do not limit the contents of the present invention described in the claims. Further, all the configurations described below are not necessarily essential to the present invention.

Example 1

FIGS. 1 and 2 show Example 1, which is used for laser treatment. The advantages of laser treatment are less bleeding, faster healing, shorter surgical time, and wider range of patients. A carbon dioxide laser surgical device is known as one of laser surgical devices.

In the carbon dioxide laser, by using the hollow optical fiber 1 for the light guide portion, the flexibility and handling properties can be made excellent. As shown in Fig. 1, the hollow optical fiber 1 has a metal mirror surface layer 3 formed on the inner surface of a hollow glass pipe 2, and an outer coating layer on the outer surface. 4 is formed. The carbon dioxide laser beam B travels while being reflected by the mirror surface layer 3.

Then, as shown in FIG. 2, the primary side that is the entrance of the hollow optical fiber 1 is connected to the carbon dioxide laser generator 5, and the secondary side that is the exit is connected to the node piece 6. The carbon dioxide laser generator 5 is connected to a loudspeaker 7 that is a speaker, and an oscillator 8 is connected to the loudspeaker 7. On the other hand, the secondary microphone 9 is connected directly or indirectly to the hollow optical fiber 1 to the hand piece 6 so that the sound of the hollow portion 1A can be captured. The secondary microphone 9 has a meaning of the secondary side downstream from the primary side, and the secondary microphone 9 that receives the sound incident on the primary side is not an outlet but a hollow optical fiber 1. An amplifier circuit 10, a filter circuit 11, and a voltmeter 12 are connected to the secondary microphone 9. In the figure, 10A indicates an amplifier circuit connected to the loudspeaker 7.

Note that the loudspeaker 7 and the secondary microphone 9 need to be provided in the hollow optical fiber 1 so that the laser beam B is not affected. For this purpose, the loudspeaker 7 and the secondary microphone 9 are placed in an optically shaded area. This is narrowed by a lens (not shown) when the laser beam B is incident on the hollow optical fiber 1 from the tube inlet II side or output from the tube outlet lO side. Therefore, the sound can be received by the loudspeaker 7 or the sound can be received by the secondary microphone 9 from the optically shaded area. In the embodiment, the loudspeaker 7 is made to enter the hollow portion 1 A on the carbon dioxide laser generator 5 or the tube inlet II side through the sound path 7 A, and the sound is incident on the secondary microphone 9. The sound is received with the other end of the sound path 9A having one end connected to the receiving portion of the side microphone 9 facing the hollow portion 1A. The hollow portion 1A side of the sound passage 9A is connected to the tube outlet 10 side.

[0035] The operation of the above configuration will be described. The carbon dioxide laser beam B generated by the carbon dioxide laser generator 5 exits from the outlet of the handpiece 6 through the hollow portion 1A of the hollow optical fiber 1. Furthermore, the loudspeaker 7 is operated by the oscillator (oscillator) 8 to generate a sound wave, and this sound wave passes through the hollow part 1A of the optical fiber 1 and exits from the outlet of the handpiece 6. It has become. This sound wave is captured by the secondary microphone 9, and the sound wave signal input to the secondary microphone 9 is electrically converted and displayed by the voltmeter 12 via the amplifier circuit 10 and the filter circuit 11. Is done. The sound wave is an elastic wave generated by the vibration of the generator (loud speaker 7) in the air or other sound medium, and includes not only the audible frequency region but also other frequency regions.

[0036] When a hole P communicating from the hollow portion 1A to the outside is temporarily formed in the hollow optical fiber 1, the carbon dioxide laser B leaks through the hole P, and human and material burnout is caused. However, in such a case, a part of the sound wave leaks from the hole P, so that the lowered sound wave is captured by the secondary microphone 9 and input to the secondary microphone 9. The sound wave signal is electrically converted and is displayed as a voltage lower than normal by the voltmeter 12 through the amplifier circuit 10 and the filter circuit 11. Therefore, when a voltage lower than normal is displayed, the carbon dioxide laser B may be leaked. For example, a control means (not shown) connected to the carbon dioxide laser generator 5 is activated to stop the laser. It is possible to take appropriate measures immediately.

[0037] Thus, in the thin hollow optical fiber 1 in which the inner diameter of the hollow portion 1A is less than 1 mm, the hollow portion 1A functions as a low-pass filter with respect to the frequency of sound, and therefore passes only a low frequency. Therefore, this method mainly uses a low frequency of 1kHz or less. At these frequencies, normally, sound incident from the primary side of the hollow optical fiber 1 from the sound source can be confirmed with sufficient intensity by the secondary microphone 9 on the secondary side. Here, if the hole P opens or breaks in the middle of the hollow optical fiber 1, the acoustic power leaks from the hole P in the defective part, so the acoustic power transmitted to the secondary microphone 9 is extremely attenuated. Therefore, the abnormal force can be confirmed by the secondary microphone 9. Therefore, the laser may be stopped immediately.

[0038] It should be noted that the hollow optical fiber 1 can be bent freely, but the force that may change the sound pressure in the bent state is very small at such a very loose curvature even if it is affected. The measurement error is below. If the hollow optical fiber 1 is bent at an acute angle, there is little force and an effect can be considered. However, in the hollow optical fiber 1, the curvature limit is 200 times or more of the inner diameter, and the bending is very loose. This is practically acceptable.

[0039] Further, the hollow optical fiber 1 is melted by the laser B, and the hollow optical fiber 1 is melted. When the inside is blocked, no sound reaches the exit side, and the sound pressure drops when the sound pressure drops rather than the sound pressure drop due to the leak. This is a hollow optical fiber

When sound is incident in 1, it becomes exactly the same as the state.

[0040] Particularly, in the case of the above-described acoustic detection in a laser surgical device, it can be used at the same time as the laser surgical device, so that no disturbing device is attached to the hand, and it can be built in a small handpiece. It does not impair the sex.

[0041] Moreover, since the leak can be detected at the moment when the hole P is opened in the middle of the hollow optical fiber 1 and the laser is immediately shut off, this is a sufficiently effective method to prevent a leak accident. is there.

[0042] In addition, for example, actual intraoperative noise may affect detection, but the frequency picked up by the secondary microphone 9 is filtered by the filter circuit 11 to perform frequency discrimination. Noise is not a problem. Furthermore, if the sound type is detected using a plurality of frequencies such as “250 Hz and 400 Hz”, the possibility of malfunction can be almost eliminated.

[0043] The gain waveform of the secondary microphone 9 changes depending on the leak position where the hole P is opened in the middle of the hollow optical fiber 1, so that the leak position can also be detected.

Example 2

FIG. 3 shows a second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

In addition to the secondary microphone 9 provided at the exit of the hollow optical fiber 1, a primary microphone 13 is provided on the primary side that is the entrance of the hollow optical fiber 1. The primary microphone 13 is connected directly or indirectly to the hollow fiber 1 so that the sound of the hollow portion 1A can be captured. The transmitter 17 is connected to the loudspeaker 7, the primary microphone 13 is connected to the A channel 15 of the analyzer (FFT analyzer 1) 14, and the B channel 16 of the analyzer (1 FFT analyzer) 14 is connected. To which a secondary microphone 9 is connected. In the figure, 10A indicates an amplifier circuit between the loudspeaker 7 and the oscillator 17, and 10B indicates an amplifier circuit between the primary microphone 13 and the A channel 15.

It should be noted that, as in the first embodiment, the primary side microphone 13 is optically arranged so as not to be affected by the laser beam B. Install in the shaded area. For example, a sound path (not shown) may be provided similarly to the secondary microphone 9.

Accordingly, the carbon dioxide laser generated by the carbon dioxide laser generator 5 exits from the outlet of the handpiece 6 through the hollow portion 1A of the hollow optical fiber 1. Furthermore, the loudspeaker 7 is operated by the oscillator 17 to generate sound waves, and these sound waves also come out from the outlet of the handpiece 6 through the hollow portion 1A!

[0048] When a hole P communicating from the hollow portion 1A to the outside is temporarily formed in the hollow optical fiber 1, a part of the sound wave leaks from the hole P, so that the lowered sound wave is generated on the secondary side. The sound wave signal input to the secondary microphone 9 is detected by the microphone mouthphone 9 and is electrically converted and input to the analyzer 14. On the other hand, the sound wave signal input to the primary microphone 13 is electrically converted and input to the analyzer 14. Then, the analyzer 14 compares the input signal from the secondary microphone 9 and the input signal from the primary microphone 13 so that the state without a hole can be analyzed.

[0049] By doing so, the same effects as the above-described embodiment can be obtained.

Example 3

FIG. 4 shows a third embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0051] The primary side microphone 13 is provided on the primary side which is the entrance of the hollow optical fiber 1, the transmitter 17 is connected to the loudspeaker 7, and the primary side is connected to the A channel 15 of the analyzer (FFT analyzer) 14. A microphone 13 is connected.

Accordingly, the carbon dioxide laser generated by the carbon dioxide laser generator 5 exits from the outlet of the handpiece 6 through the hollow portion 1A of the hollow optical fiber 1. Furthermore, the loudspeaker 7 is activated by the transmitter 7A to generate sound waves, and these sound waves also come out from the outlet of the handpiece 6 through the hollow portion 1A!

[0053] When a hole communicating from the hollow portion 1A to the outside is temporarily formed in the hollow optical fiber 1, a part of the sound wave leaks from the hole, so that the lowered sound wave is generated by the secondary microphone 9 The sound wave signal input to the secondary microphone 9 is electrically converted and input to the analyzer 14. Then, the change of the input signal from the secondary microphone 9 is passed. By performing a comparison operation at all times, it is possible to analyze the state of hole P!

[0054] By doing so, the same effects as the above-described embodiment can be obtained.

Example 4

FIG. 5 shows a fourth embodiment. The same reference numerals are given to the same parts as those in the previous embodiment, and detailed description thereof will be omitted. In Example 4, the loudspeaker 7 is connected to the tube inlet II of the hollow optical fiber 1 via the sound passage 7A, and the secondary microphone 9 is provided to the tube outlet lO side via the sound passage 9A. It is a thing.

[0056] In the fourth embodiment as well, the same effects as in the first embodiment can be obtained.

Next, experimental examples will be described. In the experimental example, the hollow optical fiber 1 was replaced with a stainless steel pipe. This is because the tube material is treated as a rigid boundary condition (sound does not propagate and is reflected), and the glass pipe 2 and the stainless steel pipe mentioned above are acoustic when viewed from the air where impedance is about 4 orders of magnitude higher when viewed from the air. This is because they are equivalent. Experimental example 1

Next, experimental examples will be described. In the experimental example, the hollow optical fiber 1 was replaced with a stainless steel pipe. This is because the tube material is treated as a rigid boundary condition (sound does not propagate and is reflected), and the glass pipe 2 and the stainless steel pipe mentioned above are acoustic when viewed from the air where impedance is about 4 orders of magnitude higher when viewed from the air. This is because they are equivalent.

FIGS. 6 to 8 show Experimental Example 1, in which a loudspeaker 7 is connected to the inlet of the stainless steel pipe 21, a primary microphone 13 is provided at the inlet of the pipe 21, and the inlet of the pipe 21 is shown. Fig. 8 shows the spectrum of 13 primary power microphones formed from a simulated leak hole P.

Example 2

FIGS. 9 to 13 show Experimental Example 2, in which a loudspeaker 7 is connected to the inlet of the stainless steel pipe 21, and the secondary microphone 9 and the primary microphone are connected to the outlet and inlet of the pipe 21. 13 and 13 and a simulated leak hole P is formed from the inlet of the pipe 21, and the gains using two of the secondary microphone 9 and the primary microphone 13 are shown in FIGS. It is. Experimental example 3

FIGS. 14 to 18 show Experimental Example 3, in which a loudspeaker 7 is connected to the inlet of the stainless steel pipe 21, a secondary microphone 9 is provided at the inlet of the pipe 21, and the inlet of the pipe 21 is shown. A simulated leak hole P is formed from Fig. 15 and Fig. 18 shows the spectrum from the secondary microphone 9.

[0062] From the above experiment, in the hollow optical fiber 1 having the hollow portion 1A whose inner diameter is less than 1 mm, the hollow portion 1A functions as a low-pass filter with respect to the sound frequency, so that only a low frequency is obtained. The reason for adopting a low frequency of 1kHz or less mainly in this method appears because a wide frequency range from a very low frequency to about 1kHz appears. Therefore, it is possible to monitor by using a plurality of frequencies or a frequency range that is not a single frequency. This can increase the reliability of the measurement. In the experiment, we collected data using two microphone-headphones, but one microphone is sufficient on the opposite side of the sound source.

Example 4

[0063] Further, other experimental examples will be described. The same parts as those in the above-described examples and experimental examples will be described with the same reference numerals.

FIGS. 19 to 24 show Experimental Example 4, and when the primary microphone 13 is connected to the pipe 21, the tip of the primary microphone 13, that is, the hole formed in the sound collecting portion 13 A and the pipe 21. In order to insulate vibration between 21 A, a pipe-like vibration insulation relay member 22 such as silicon or rubber is interposed. Similarly, a pipe-shaped vibration insulation relay member 23 such as silicon or rubber is interposed between the loudspeaker 7 and the hole formed in the pipe 21 to insulate vibration, and the tip of the secondary microphone 9 In other words, a pipe-shaped vibration insulation relay member 24 such as silicon or rubber is interposed between the sound collecting portion 9A and the hole formed in the pipe 21 in order to provide vibration insulation.

[0065] As shown in Fig. 21, as a result of experiments using two microphones 9, 13, the sound pressure leaks from the leak hole, so that the sound pressure at the outlet side decreases and the transfer function (Gain) decreases. Can be seen.

[0066] Figs. 22 and 23 show the air column of the pipe 21 as a transfer matrix using the wave equation. The derivation of the equation for theoretically determining the sound pressure ratio G (gain) between the inlet side (primary side) and the outlet side (secondary side) is shown.

[0067] In the figure, P is the sound pressure, U is the volume velocity, Z is the impedance, L1 is the length to the loudspeaker 7 (or microphone 13) force hole P in the pipe 21,

L2 is the length from the hole P to the microphone 9 in the pipe 21, and A, B, C, and D are four-terminal constants.

[0068] Fig. 24 shows a comparison between the theoretical values and the experimental results, comparing the theoretical values and the previous experimental values for the leak positions 200mm, 500mm, and 1 000mm. The theoretical value and the experimental value at each leak position In the frequency band of about 200 to 800 Hz, the trends agree, and the secondary microphone 9 at the exit picks up the sound incident in the pipe 21 and agrees well in the frequency band.

[0069] The difference between the theoretical value and the measured value in the low frequency band enclosed by the left circle.

Originally, the experimental value is also considered to be large (as in the theoretical value), and the gain is considered to decrease. However, due to the leak, the signal from the exit microphone (secondary microphone 9) becomes smaller than the noise floor, and the exit microphone ( This is because the signal from the secondary microphone 9) becomes the noise floor!

[0070] About the difference in the right circle.

The result up to 1kHz is sufficient, but it is measured up to 2kHz for reference. In the narrow tube (pipe 2 1), the sound is less likely to be transmitted at higher frequencies, and as a result, the outlet microphone (secondary microphone mouth) In this area, the signal-to-noise ratio is low.In this region, the reliability of the signal from the outlet microphone (secondary microphone 9) is low, and this does not change in the circled part at any leak position. From the fact that it shows a tendency, it can be seen that it picks up the noise floor!

Experimental Example 5

FIGS. 25 to 26 show Experimental Example 5, which is a configuration diagram at the time of leak detection using only the outlet side microphone (secondary side microphone 9), and the outlet side microphone (secondary side microphone 9). ), And a pipe-shaped vibration insulation relay member 23 such as silicon or rubber is interposed between the loudspeaker 7 and the hole formed in the pipe 21 for vibration insulation. is there.

[0072] In the spectrum experiment results using only the exit side microphone (secondary side microphone 9), the sound pressure is reduced by the leak, so if there is a leak, there is no leak. Compared to, the spectrum (sound pressure level) is reduced, and leak detection is possible. Similar to the previous experiment, a similar drop in sound pressure was confirmed at the leak position not shown in the graph.

[0073] If there is a leak, it is thought that the sound pressure has dropped to “sound pressure as shown by red dashed lines at the left and right ends of the graph (only this red broken line is virtually assumed for explanation)”. Floor force Because the sound pressure is high, the microphone (secondary microphone 9) picked up the noise floor, and it was thought that the spectrum was similar to the experimental results. Sound pressure was measured without driving the speaker to see the bottom of noise.

In this way, leak can be detected by obtaining the gain of the transfer function in Neuve 21. In addition, the amount of gain reduction due to leakage can be predicted by theoretical analysis, and leakage can also be detected by measuring the spectrum with the secondary microphone 9 or by changing the voltage.

Experimental Example 6

[0075] FIGS. 27 to 28 show Experimental Example 6, which is a configuration diagram of leak detection using only the outlet microphone (secondary microphone 9) (assumed in practical use), and the outlet microphone (2 Since leak detection is possible only with the secondary microphone 9), a simple and practical leak detection device can be constructed. FIG. 27 is a configuration diagram thereof.

[0076] In the stainless steel pipe (pipe 21), only one frequency sound is incident, and the sound is picked up by the outlet microphone (secondary microphone 9). The microphone (secondary microphone 9) is picked up. Since the sound is converted into an electrical signal, the voltage is monitored by the voltmeter 26 via the amplifier 10 and the filter 25. Therefore, an expensive measuring instrument is unnecessary, and the microphone (secondary microphone 9) does not need to have a flat frequency characteristic. Leak detection is possible only with simple and inexpensive equipment.

[0077] As shown in Fig. 28, the voltage measurement results when a 250Hz sine wave (pure sound) was made to enter the stainless steel pipe (pipe 21). However, since the voltage drops greatly, it is easy to detect leaks.

Industrial applicability

[0078] As described above, the method and apparatus according to the present invention can be applied to various applications. Brief Description of Drawings

FIG. 1 is a cross-sectional view of an optical fiber showing Example 1 of the present invention, FIG. 1 (A) is a cross-sectional view at normal time, FIG. 1 (B) is a cross-sectional view at the time of laser light leakage, ) Is a partially cutaway perspective view when a laser beam leaks.

FIG. 2 is an explanatory view showing Example 1 of the present invention.

FIG. 3 is an explanatory view showing Example 2 of the present invention.

FIG. 4 is an explanatory view showing Example 3 of the present invention.

FIG. 5 is an explanatory view showing Example 4 of the present invention.

FIG. 6 is an explanatory view showing Experimental Example 1 of the present invention.

FIG. 7 is an explanatory view of the position of a simulated leak hole showing Experimental Example 1 of the present invention.

FIG. 8 is a graph of an experiment with a primary side (inlet side) microphone showing Experimental Example 1 of the present invention.

FIG. 9 is an explanatory view showing Experimental Example 2 of the present invention.

FIG. 10 is a graph of an experiment with a leak position of 100 to 500 _mm using two microphones showing Experimental Example 2 of the present invention.

FIG. 11 is a graph of an experiment with a leak position of 600 to 1000 _mm using two microphones showing Experimental Example 2 of the present invention.

FIG. 12 is a graph of an experiment in which a leak position is 1100 to 1500 mm using two microphones showing Experimental Example 2 of the present invention.

FIG. 13 is a graph of an experiment in which a leak position is 1600 to 1900 mm using two microphones showing Experimental Example 2 of the present invention.

FIG. 14 is an explanatory view showing Experimental Example 3 of the present invention.

FIG. 15 is a graph of an experiment in which the leak position at the secondary side (exit side) microphone showing Experimental Example 3 of the present invention is 100 to 500 mm.

FIG. 16 is a graph of an experiment with a leak position of 600 to 1000 mm in a secondary side (exit side) microphone showing Experimental Example 3 of the present invention.

FIG. 17 is a graph of an experiment in which the leak position at the secondary side (exit side) microphone showing Experiment Example 3 of the present invention is 1100 to 1500 mm.

[FIG. 18] The leak position at the secondary side (exit side) microphone showing Experimental Example 3 of the present invention is 1600. ~ 1900mm experiment graph.

FIG. 19 is an explanatory diagram of an experimental apparatus in which microphones are installed on the primary side and the secondary side, showing Experimental Example 4 of the present invention.

FIG. 20 is an explanatory view showing measurement conditions showing Experimental Example 4 of the present invention.

FIG. 21 is a gain graph using two microphones showing Experimental Example 4 of the present invention.

FIG. 22 shows experimental example 4 of the present invention, FIG. 22 (A) is a plan view of a pipe, FIG. 22 (B) is an explanatory diagram of a transfer matrix, and FIG. 22 (C) is a formula of a transfer matrix. Yes.

FIG. 23 shows another transfer matrix formula showing Experimental Example 4 of the present invention.

24] A graph showing the comparison between the theoretical analysis and experimental results showing Experimental Example 4 of the present invention.

FIG. 25 is an explanatory diagram of an experimental apparatus in which a microphone is installed on the secondary side, showing Experimental Example 5 of the present invention.

FIG. 26 is a graph showing a spectrum of a secondary microphone showing Experimental Example 5 of the present invention.

FIG. 27 is an explanatory diagram of an experimental apparatus showing Experimental Example 6 of the present invention.

[28] FIG. 28 is a graph of leak detection by measurement showing Experimental Example 6 of the present invention.

Explanation of symbols

1 Hollow optical fiber

5 Carbon dioxide laser generator

7 Loudspeaker

9 Secondary microphone

Claims

The scope of the claims

[1] In a method of transmitting laser light using a hollow optical fiber, a sound wave is incident from the primary side of the hollow optical fiber and the sound wave is detected from the secondary side, whereby the hollow light fiber is lost or clogged. How to detect.

[2] In the method of transmitting laser light using a hollow optical fiber, a sound wave is incident from the primary side of the hollow optical fiber and the sound wave is detected from the secondary side, and the primary side sound wave and the secondary sound wave are detected. A method for detecting defects and clogging of hollow optical fibers by comparing side acoustic waves.

[3] The optical fiber defect or clogging according to any one of claims 1 to 2, wherein the primary side acoustic wave signal and the secondary side acoustic wave signal are electrically detected. how to.

4. The optical fiber according to any one of claims 1 to 3, wherein the sound wave is generated by a speaker and the secondary sound wave is detected by a microphone. Method.

[5] The method for detecting a loss or clogging of an optical fiber according to any one of claims 1 to 4, wherein the primary side acoustic wave has a low frequency of 1 kHz or less.

6. The method for detecting an optical fiber defect or clogging according to any one of claims 1 to 5, wherein the primary side acoustic wave has a plurality of frequencies.

[7] A hollow optical fiber loss / clogging detection device, characterized in that a sound source for making sound waves incident on the primary side of the hollow optical fiber is provided, and a detection means for detecting the sound wave is provided on the secondary side.

8. The hollow optical fiber loss or clogging detection device according to claim 7, wherein a speaker is connected to the gas laser generator side, and a secondary microphone port is connected to the hollow optical fiber.

[9] The hollow optical fiber defect or clogging detection device according to [8], wherein the hollow optical fiber is provided with a primary microphone.

10. The hollow optical fiber defect or clogging detection device according to any one of claims 7 to 9, wherein the secondary side is a handpiece side that is connected to the hollow optical fiber and emits laser light. .