Patent Description:
There is a known technique for providing a medical treatment by inserting a catheter with an optical fiber inserted therein into the patient's body. In such an optical fiber probe for medical use, since the diameter of the optical fiber becomes smaller with the decrease in the diameter of the catheter, there is a risk that the optical fiber will be strongly bent or broken when the catheter is inserted into the patient's body.

For example, Patent Literatures <NUM> and <NUM> disclose a technique for detecting the curvature of a tubular member, such as an endoscope, which is inserted into the body, or estimating the curved shape of the tubular member.

Further relevant documents are: <CIT>, <CIT> and <CIT>.

When the optical fiber is strongly bent during insertion of the catheter, light will leak out at the curved portion. Therefore, for example, when an ablation medical treatment is performed with laser light, the optical power reaching a desired position could be reduced, or the ablation could be applied to a position not in need due to the leakage of light at the curved portion.

For the reasons describe above, there has been a need for a technique that accurately measures the bending loss of the optical fiber during insertion of the catheter, that is, when the optical fiber is in operation, and determines the presence or absence of a bend on the optical fiber. However, Patent Literatures <NUM> and <NUM> mentioned above do not disclose such a technique.

The present invention has been made in consideration of the above, and has an object to provide an optical fiber state detection system, which can accurately measure the bending loss of an optical fiber in operation, and determine the presence or absence of a bend on the optical fiber.

To resolve the problem and attain the object, an optical fiber state detection system according to an embodiment of the present invention includes: a first light source that outputs a monitor-related light for monitoring a state of an optical fiber; a reflection mechanism that reflects the monitor-related light propagated through the optical fiber; a light receiving part that receives a reflected light reflected by the reflection mechanism; a tap coupler provided between the reflection mechanism and both the first light source and the light receiving part such that the first light source and the light receiving part are connected the tap coupler; and a control part. Further, when the control part detects that a received optical power of the reflected light is greater than <NUM> and lower than a predetermined threshold value, the control part outputs information on a decrease in the received optical power to outside.

An optical fiber state detection system includes: a first light source that outputs a monitor-related light for monitoring a state of an optical fiber; a reflection mechanism that reflects the monitor-related light propagated through the optical fiber; a light receiving part that receives a reflected light reflected by the reflection mechanism; a tap coupler provided between the reflection mechanism and both the first light source and the light receiving part such that the first light source and the light receiving part are connected the tap coupler; a second light source that outputs an ablation-related light; a wave multiplexer that multiplexes the monitor-related light and the ablation-related light; and a control part. Further, the first light source and the second light source are connected to the wave multiplexer, the wave multiplexer and the light receiving part are connected to the tap coupler, the monitor-related light and the ablation-related light are different from each other in wavelength, the reflection mechanism transmits the ablation-related light, and when the control part detects that a received optical power of the reflected light is greater than <NUM> and lower than a predetermined threshold value, the control part shuts down the second light source.

In the optical fiber state detection system according to an embodiment of the present invention, a wavelength of the monitor-related light is a wavelength in a visible light wavelength bandwidth.

In the optical fiber state detection system according to an embodiment of the present invention, the monitor-related light is a flat top beam.

The monitor-related light and the ablation-related light are same as each other in beam shape.

In the optical fiber state detection system according to an embodiment of the present invention, a mechanism that cuts a wavelength of the ablation-related light is provided on a front side of the light receiving part.

According to the present invention, it is possible to accurately measure the bending loss of an optical fiber in operation, and determine the presence or absence of a bend on the optical fiber.

An optical fiber state detection system according to the present invention will be explained below with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments. Further, the constituent elements in the following embodiments encompass those which can be easily used as replacements by a person skilled in the art, or which are substantially equivalent thereto.

An optical fiber state detection system (which will be simply referred to as "state detection system", hereinafter) <NUM> according to this embodiment includes, as illustrated in <FIG>, a laser apparatus <NUM>, an optical fiber probe <NUM> equipped with a reflection mechanism <NUM>, a connector <NUM> that connects the laser apparatus <NUM> and the optical fiber probe <NUM> to each other, optical fibers <NUM>, a control part <NUM>, and a display part <NUM>. Here, the connector <NUM> is not essential, and thus may be omitted. Further, in <FIG>, the optical fibers <NUM> are illustrated by solid lines.

The laser apparatus <NUM> includes a monitor-related LD <NUM>, a monitor PD <NUM>, a tap coupler <NUM>, and optical fibers <NUM> that connect these components. Here, the "LD" stands for "laser diode", and the "PD" stands for "photodiode".

The monitor-related LD <NUM> serves as a light source (first light source) that outputs a monitor-related light TL for monitoring the state of an optical fiber <NUM>. The monitor-related LD <NUM> is connected to the input side of the tap coupler <NUM> via an optical fiber <NUM>.

The laser apparatus <NUM> may be provided with a plurality of monitor-related LDs <NUM> that output lights different from each other in wavelength. Alternatively, the monitor-related LD <NUM> may be formed of a structure integrally combing a plurality of LDs that output lights different from each other in wavelength. Here, the output of the monitor-related LD <NUM> is set to <NUM> mW or less, for example. Further, the wavelength of the monitor-related light TL is set to be a wavelength that falls within a range of the visible light wavelength bandwidth to the near infrared wavelength bandwidth (<NUM> to <NUM>,<NUM>), and preferably to be a wavelength that falls within a range of the visible light wavelength bandwidth (<NUM> to <NUM>).

Now, <FIG> is a diagram for explaining an example of the bending loss characteristic of an optical fiber <NUM>, which is a graph showing the relationship between the wavelength of light and the bending loss of the optical fiber <NUM>. Here, the bending loss (loss by a bend) is defined by the amount of increase in transmission loss when the optical fiber <NUM> is bent with a predetermined bending radius, for example.

As illustrated in <FIG>, the bending loss of the optical fiber <NUM> is smaller on the shorter wavelength side and larger on the longer wavelength side. This means that, for example, when the bending loss of the optical fiber <NUM> is measured by using a monitor-related light TL with a shorter wavelength (in the visible light wavelength bandwidth) and is determined that "there is a bend", it will be determined that "there is a bend" even if a monitor-related light TL with a longer wavelength (in a wavelength bandwidth longer than the visible light wavelength bandwidth) is used.

Therefore, as described above, when a light in the visible light wavelength bandwidth is used as the monitor-related light TL, it becomes possible to also determine the presence or absence of a bend on the optical fiber <NUM> of the case where a monitor-related light TL in a longer wavelength bandwidth is used. Here, for example, in a case where it is determined that "there is no bend" when a monitor-related light in the visible light wavelength bandwidth is used, and it is determined that "there is a bend" when a monitor-related light in a longer wavelength bandwidth is used, it may be acceptable to overestimate the bending loss by using a light in a wavelength bandwidth longer than the visible light wavelength bandwidth as the monitor-related light TL.

The monitor-related light TL is composed of a flat top beam (top hat beam). In order to make the monitor-related light TL into a flat top beam, for example, there is a method to be used, such as a method of arranging a combiner <NUM> between the monitor-related LD <NUM> and the tap coupler <NUM> as illustrated in <FIG>, a method of performing mode mixing by applying a bend to the optical fiber <NUM> as illustrated by a circle in <FIG>, or a method of applying vibration to the optical fiber <NUM>.

Note that, in <FIG> and <FIG>, the optical fiber probe <NUM>, the connector <NUM>, the control part <NUM>, and the display part <NUM> are omitted from the illustration. Here, as regards the combiner <NUM> illustrated in <FIG>, the number thereof is not particularly limited, but may be set to two or more. Further, the bending radius of the optical fiber <NUM> illustrated in <FIG> is set to a value (for example r = <NUM>) of a long term bending radius (Long Term Bend Radius: LTBR) of the optical fiber <NUM>, or the like. Returning to <FIG>, an explanation will be given of the rest of the configuration.

The monitor PD <NUM> serves as a light receiving part that receives and monitors the reflected light RL reflected by the reflection mechanism <NUM>. The monitor PD <NUM> is connected to the input side of the tap coupler <NUM> via an optical fiber <NUM>. Here, a plurality of monitor PDs <NUM> may be arranged, as in the monitor-related LD <NUM>, such that, for example, the plurality of monitor PDs <NUM> may receive lights different from each other in wavelength output from the plurality of monitor-related LDs <NUM>.

The tap coupler <NUM> is arranged between the monitor-related LD <NUM> and monitor PD <NUM> and the reflection mechanism <NUM>. The monitor-related LD <NUM> and the monitor PD <NUM> are connected to the input side of the tap coupler <NUM> via optical fibers <NUM>. Further, the connector <NUM> is connected to the output side of the tap coupler <NUM>. The tap coupler <NUM> is preferably an asymmetric tap coupler, and the composition ratio of the tap coupler <NUM> can be set to, for example, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, etc. Here, in <FIG>, the ratio of input ports to output ports of the tap coupler <NUM> is <NUM>:<NUM>, but the ratio may be set to <NUM>:<NUM>.

The reflection mechanism <NUM> serves to reflect the monitor-related light TL propagated through the optical fiber <NUM>. The reflection mechanism <NUM> is composed of, for example, an FBG (Fiber Bragg Grating) or reflective film, and is provided on the distal end side of the optical fiber <NUM> in the optical fiber probe <NUM>. Here, when the reflection mechanism <NUM> is composed of a reflective film, the reflection mechanism <NUM> is preferably provided at the distal end of the optical fiber <NUM>. Alternatively, when the reflection mechanism <NUM> is composed of an FBG, the reflection mechanism <NUM> is preferably provided slightly inside the distal end of the optical fiber <NUM>.

The monitor-related light TL propagated toward the distal end side of the optical fiber <NUM> and reflected by the reflection mechanism <NUM> is further propagated back toward the proximal end side of the optical fiber <NUM> as the reflected light RL. Then, the reflected light RL is input to the monitor PD <NUM> via the connector <NUM> and the tap coupler <NUM>.

Each of the optical fibers <NUM> is formed of, for example, a multi-mode optical fiber. This optical fiber <NUM> has, for example, a core diameter of <NUM> and a clad diameter of <NUM>, and is composed of a step-index type optical fiber including a coating, such as an acrylate coating film or polyimide coating film.

Here, the core diameter of the optical fiber <NUM> on the laser apparatus <NUM> side (which will be referred to as "apparatus side", hereinafter) and the core diameter of the optical fiber <NUM> on the optical fiber probe <NUM> side (which will be referred to as "probe side", hereinafter) may be different from each other. In this case, the core diameter of the optical fiber <NUM> on the apparatus side is preferably set smaller than the core diameter of the optical fiber <NUM> on the probe side.

Now, <FIG> is a diagram for explaining an example of the bending loss characteristic of the optical fiber <NUM> depending on the core diameter of the optical fiber <NUM>, which is a graph showing the relationship between the bending radius of the optical fiber <NUM> and the bending loss. The example <NUM> of <FIG> assumes, for example, as illustrated in <FIG>, a system configuration which is provided with a light source on the apparatus side and a power meter on the probe side, and in which the core diameter of the optical fiber <NUM> on the apparatus side is <NUM> and the core diameter of the optical fiber <NUM> on the probe side is <NUM>. This example <NUM> assumes, for example, an ablation-associated line in which an ablation-related LD described later is arranged instead of the monitor-related LD <NUM> in <FIG>.

The example <NUM> of <FIG> assumes, for example, as illustrated in <FIG>, a system configuration which is provided with a light source on the apparatus side and a power meter on the probe side, and in which the core diameter of the optical fiber <NUM> on the apparatus side is <NUM>, the core diameter of the optical fiber <NUM> between two connectors <NUM> on the probe side is <NUM>, and the core diameter of the optical fiber <NUM> between the connector <NUM> and the power meter on the probe side is <NUM>. This example <NUM> assumes the reflection monitor-associated line illustrated in <FIG>. Further, the example <NUM> of <FIG> assumes, for example, a system configuration in which the core diameter of the optical fiber <NUM> is <NUM> on each of the apparatus side and the probe side, in <FIG>.

As illustrated in <FIG>, it can be seen that, in the cases where the core diameter of the optical fiber <NUM> on the apparatus side and the core diameter of the optical fiber <NUM> on the probe side are different from each other (see the examples <NUM> and <NUM>), the bending loss becomes larger and the sensitivity to the bending loss is increased, as compared with the case where the core diameters on both sides are the same as each other (see the example <NUM>). Therefore, when the core diameter of the optical fiber <NUM> is set different between the apparatus side and the probe side, the apparent bending loss is increased, and makes it easier to detect the occurrence of a bend on the optical fiber <NUM>. Here, when the core diameter of the optical fiber <NUM> is different between the apparatus side and the probe side, it is necessary to correct the difference in the apparent bending loss with respect to the value of the actual bending loss, by using, for example, a correlation table or the like.

The control part <NUM> includes an arithmetic section and a storage section, which are not illustrated. The arithmetic section serves to perform various types of arithmetic processing necessary for the control to be executed by the control part <NUM> and the functions to be realized by the control part <NUM>, and is composed of, for example, a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or both a CPU and an FPGA. On the other hand, the storage section includes, for example, a subsection composed of a ROM (Read Only Memory) that stores various programs, data, and so forth to be used by the arithmetic section to perform arithmetic processing, and a subsection composed of a RAM (Random Access Memory) to be used as the work space when the arithmetic section performs arithmetic processing and also used for storing the result of arithmetic processing of the arithmetic section.

Further, the control part <NUM> includes an input section (not illustrated) that receives inputs, such as current signals from the monitor PD <NUM>, and an output section (not illustrated) that outputs the drive current to the monitor-related LD <NUM> and instruction signals and various types of information to the display part <NUM>, on the basis of the results of various types of arithmetic processing.

The display part <NUM> is a part that outputs various types of information to the operator of the laser apparatus <NUM> and displays characters and symbols to notify the outside or gives warning with an alarm or the like, in response to instruction signals from the control part <NUM>, and is composed of, for example, a liquid crystal display.

In the optical fiber state detection system <NUM> configured as described above, when the control part <NUM> detects that the received optical power of the reflected light RL received by the monitor PD <NUM> is greater than <NUM> and lower than a predetermined threshold value, the control part <NUM> outputs information on the decrease in the received optical power to the outside. Specifically, the control part <NUM> outputs to the display part <NUM> such information that the received optical power has decreased. In this case, the control part <NUM> can determine that a bent has occurred on the optical fiber <NUM> in the optical fiber probe <NUM>. The control part <NUM> may sound an alarm or the like by the display part <NUM> to notify the outside (operator) of the decrease in the received optical power, that is, the occurrence of a bend on the optical fiber <NUM>. The predetermined threshold described above can be set by the value of the received optical power attenuated by <NUM>% or <NUM> dB from the value of the received optical power under the normal condition.

In addition, when the change rate of the received optical power of the reflected light RL becomes large within a certain period of time, such as when the received optical power of the reflected light RL decreases sharply within a short period of time, for example, the control part <NUM> may determine that a bent has occurred on the optical fiber <NUM> in the optical fiber probe <NUM>, even if the received optical power of the reflected light RL has not become lower than the predetermined threshold described above.

With the optical fiber state detection system <NUM> according to the first embodiment described above, the bending loss of the optical fiber <NUM> in operation is accurately measured, and, when the received optical power of the reflected light has decreased, information on the decrease in the received optical power can be output. Consequently, it is possible to determine the presence or absence of a bend on the optical fiber <NUM>.

An optical fiber state detection system <NUM> according to this embodiment includes, as illustrated in <FIG>, a laser apparatus 10A, an optical fiber probe 30A, a connector <NUM> that connects the laser apparatus 10A and the optical fiber probe 30A to each other, optical fibers <NUM>, a control part <NUM>, and a display part <NUM>. Here, the configurations of the connector <NUM>, the optical fiber <NUM>, the control part <NUM>, and the display part <NUM> in <FIG> are the same as those of the first embodiment described above (see <FIG>).

The laser apparatus 10A includes a monitor-related LD <NUM>, an ablation-related LD <NUM>, a wave multiplexer <NUM>, a monitor PD <NUM>, a tap coupler <NUM>, and optical fibers <NUM> that connect these components. Further, the optical fiber probe 30A is equipped with a reflection mechanism <NUM>. Here, the optical fiber probe 30A may further include a side-face irradiation mechanism that changes the traveling direction of an ablation-related light TL2, which has been transmitted through the reflection mechanism <NUM>, to a direction different from the traveling direction before the transmission through the reflection mechanism <NUM>, and then radiates the light.

The monitor-related LD <NUM> serves as a light source (first light source) that outputs a monitor-related light TL1 for monitoring the state of an optical fiber <NUM>. The monitor-related LD <NUM> is connected to the input side of the wave multiplexer <NUM> via an optical fiber <NUM>. On the other hand, the monitor PD <NUM> is connected to the input side of the tap coupler <NUM> via an optical fiber <NUM>.

The laser apparatus <NUM> may be provided with a plurality of monitor-related LDs <NUM> that output lights different from each other in wavelength. Here, for example, when two monitor-related LDs <NUM> are used, it is preferable to configure one monitor-related LD <NUM> to output a light in a wavelength bandwidth shorter than the wavelength bandwidth of the ablation-related light TL2, and configure the other monitor-related LD <NUM> to output a light in a wavelength bandwidth longer than the wavelength bandwidth of the ablation-related light TL2. In this way, when one monitor-related LD <NUM> outputs a light shorter in wavelength than the ablation-related light TL2, and the other monitor-related LD <NUM> outputs a light longer in wavelength than the ablation-related light TL2, the estimation accuracy of the bending loss is further improved.

The ablation-related LD <NUM> serves as a light source (second light source) that outputs the ablation-related light TL2. The ablation-related LD <NUM> is connected to the input side of the wave multiplexer <NUM> via an optical fiber <NUM>. Note that, when the laser apparatus 10A is used for a laser medical treatment by a medical catheter, the ablation-related light TL2 output from the ablation-related LD <NUM> is a light in a wavelength bandwidth, which is the so-called "living window", that is, a light in a wavelength bandwidth of <NUM> to <NUM>,<NUM>. Here, the ablation-related light TL2 has a wavelength different from the monitor-related light TL1. Further, the output of the ablation-related LD <NUM> is set to <NUM> W or more, for example.

Here, the monitor-related light TL1 and the ablation-related light TL2 preferably have the same beam shape. This is because the bending loss of the optical fiber <NUM> is mode-dependent, so there is a case where the value changes when the bending loss is measured by a light source with a different beam shape.

In order to make the beam shape of the monitor-related light TL1 and the beam shape of the ablation-related light TL2 the same as each other, for example, as in the laser apparatus 10B illustrated in <FIG>, the monitor-related light TL1 and the ablation-related light TL2 are multiplexed (synthesized) on the upstream side of the laser apparatus 10B. Here, an optical component <NUM> illustrated in <FIG> is not particularly limited to a specific configuration, but may be composed of, for example, an isolator or filter, another component formed of an optical fiber, or the like. In this way, when the monitor-related light TL1 and the ablation-related light TL2 are made to have the same beam shape, the measurement error of the bending loss can be reduced.

The wave multiplexer <NUM> multiplexes the monitor-related light TL1 and the ablation-related light TL2. The wave multiplexer <NUM> is composed of, for example, a WDM (wavelength division multiplexing) coupler, combiner, tap coupler, spatial coupling optical system, or the like. The wave multiplexer <NUM> is connected to the input side of the tap coupler <NUM> via an optical fiber <NUM>.

The reflection mechanism <NUM> is composed of, for example, an FBG or reflective film, and servers to reflect the monitor-related light TL1, and to transmit the ablation-related light TL2 and radiate the ablation-related light TL2 to the outside.

In an optical fiber state detection system 1A configured as described above, when the control part <NUM> detects that the received optical power of the reflected light RL received by the monitor PD <NUM> is greater than <NUM> and lower than a predetermined threshold value, the control part <NUM> outputs information on the decrease in the received optical power to the outside. Specifically, the control part <NUM> outputs to the display part <NUM> such information that the received optical power has decreased. In this case, the control part <NUM> can determine that a bent has occurred on the optical fiber <NUM> in the optical fiber probe 30A. The control part <NUM> may sound an alarm or the like by the display part <NUM> to notify the outside (operator) of the decrease in the received optical power, that is, the occurrence of a bend on the optical fiber <NUM>. Further, the control part <NUM> may stop the output of the ablation-related light TL2 by shutting down the ablation-related LD <NUM>. Here, the predetermined threshold described above can be set by the same method as in the first embodiment.

With the optical fiber state detection system 1A according to the second embodiment described above, the bending loss of the optical fiber <NUM> in operation is accurately measured, and, when the received optical power of the reflected light has decreased, information on the decrease in the received optical power can be output. Consequently, it is possible to determine the presence or absence of a bend on the optical fiber <NUM>. Further, with the state detection system 1A, when a bent has occurred on the optical fiber <NUM>, the output of the ablation-related light TL2 can be stopped by shutting down the ablation-related LD <NUM>. Consequently, it is possible to prevent the ablation from being applied to a position not in need.

An optical fiber state detection system according to this embodiment includes a mechanism for cutting the wavelength of the ablation-related light TL2, provided on the front side of the monitor PD <NUM>. Hereinafter, an explanation will be given of three configuration examples of this embodiment with reference to <FIG>. Note that, in <FIG>, the optical fiber probe 30A and the connector <NUM> are omitted from the illustration.

An optical fiber state detection system 1C according to the first configuration example includes a laser apparatus 10C, which is provided with, as illustrated in <FIG>, a light source <NUM>, a monitor PD <NUM>, an ablation-related light cut mechanism <NUM>, and a tap coupler <NUM>. Here, the configurations of the monitor PD <NUM> and the tap coupler <NUM> in <FIG> are the same as those of the first embodiment described above (see <FIG>).

The light source <NUM> serves to output a monitor-related light TL1 and an ablation-related light TL2. The light source <NUM> is connected to the input side of the tap coupler <NUM> via an optical fiber <NUM>. On the other hand, the monitor PD <NUM> is connected to the ablation-related light cut mechanism <NUM> via an optical fiber <NUM>.

The ablation-related light cut mechanism <NUM> is arranged between the monitor PD <NUM> and the tap coupler <NUM>. The ablation-related light cut mechanism <NUM> is composed of, for example, a filter, WDM coupler, or the like. Here, for example, when the optical fiber <NUM> in the optical fiber probe 30A is moved while the monitor-related light TL1 and the ablation-related light TL2 are simultaneously output from the light source <NUM>, there is a case where part of the ablation-related light TL2 is propagated toward the monitor PD <NUM>. In a case where the monitor PD <NUM> has light receiving sensitivity even at the wavelength of the ablation-related light TL2, when the monitor-related light TL1 is input to the monitor PD <NUM> while being overlapped with the ablation-related light TL2, the monitor PD <NUM> cannot properly receive only the reflected light RL derived from the monitor-related light TL1, and thus a measurement error occurs in the bending loss. In light of this, the ablation-related light cut mechanism <NUM> is arranged on the front side of the monitor PD <NUM>, and thereby makes it possible to cause only a specific wavelength light (the reflected light RL derived from the monitor-related light TL1) to be input to the monitor PD <NUM>.

An optical fiber state detection system 1D according to the second configuration example includes a laser apparatus 10D, which is provided with, as illustrated in <FIG>, a light source <NUM>, a monitor PD <NUM>, an ablation PD <NUM>, an ablation-related light cut mechanism <NUM>, and tap couplers 13A and 13B. Here, the configurations of the light source <NUM>, the monitor PD <NUM>, and the ablation-related light cut mechanism <NUM> in <FIG> are the same as those of the first configuration example described above (see <FIG>).

The light source <NUM> is connected to the tap coupler 13B via an optical fiber <NUM>. On the other hand, the monitor PD <NUM> is connected to the ablation-related light cut mechanism <NUM> via an optical fiber <NUM>. Further, the ablation PD <NUM> is connected to the tap coupler 13A via an optical fiber <NUM>.

The tap coupler 13A branches a return light coming from the tap coupler 13B side into a first return light RL1 and a second return light RL2. Here, the return light includes the reflected light of the monitor-related light TL1 reflected by the reflection mechanism <NUM>, which is not illustrated, and part of the ablation-related light TL2. The tap coupler 13A outputs the first return light RL1 to the ablation-related light cut mechanism <NUM> via an optical fiber <NUM>, and outputs the second return light RL2 to the ablation PD <NUM>. The output side of the tap coupler 13A is connected to the input side of the tap coupler 13B via an optical fiber <NUM>.

As described above, the ablation-related light cut mechanism <NUM> is arranged on the front side of the monitor PD <NUM>, and thereby makes it possible to cause only a specific wavelength light (the first return light RL1) to be input to the monitor PD <NUM>. Here, the received optical power on the ablation PD <NUM> can be used to measure the power of the ablation-related light TL2.

An optical fiber state detection system 1E according to the third configuration example includes a laser apparatus 10E, which is provided with, as illustrated in <FIG>, a light source <NUM>, a monitor PD <NUM>, an ablation PD <NUM>, a WDM coupler <NUM>, and a tap coupler 13B. Here, the configurations of the light source <NUM>, the monitor PD <NUM>, the ablation PD <NUM>, and the tap coupler 13B in <FIG> are the same as those of the second configuration example described above (see <FIG>).

The light source <NUM> is connected to the tap coupler 13B via an optical fiber <NUM>. On the other hand, the monitor PD <NUM> is connected to the WDM coupler <NUM> via an optical fiber <NUM>. Further, the ablation PD <NUM> is connected to the WDM coupler <NUM> via an optical fiber <NUM>.

The WDM coupler <NUM> demultiplexes a first return light RL1 and a second return light RL2. Then, the WDM coupler <NUM> outputs the first return light RL1 to the monitor PD <NUM>, and outputs the second return light RL2 to the ablation PD <NUM>, via the optical fibers <NUM>. The output side of the WDM coupler <NUM> is connected to the input side of the tap coupler 13B via an optical fiber <NUM>.

As described above, the WDM coupler <NUM> is arranged on the front side of the monitor PD <NUM> and the ablation PD <NUM>, and thereby makes it possible to cause only a specific wavelength light (the first return light RL1 or second return light RL2) to be input to each of the monitor PD <NUM> and the ablation PD.

In the above descriptions, the optical fiber bend detection system according to each of the embodiments of the present invention has been specifically explained in the form for implementing the invention. However, the gist of the present invention is not limited to these descriptions, and should be broadly interpreted on the basis of the scope of the claims. Further, it goes without saying that various changes, modifications, and so forth based on these descriptions are also included in the gist of the present invention.

For example, in the embodiments described above, the explanations have been given on the assumption that the laser apparatus <NUM>, 10A, 10B, 10C, 10D, or 10E is used for a medical catheter or the like, but the application of the laser apparatus <NUM>, 10A, 10B, 10C, 10D, or 10E is not limited to the medical use.

Further, in the embodiments described above, the explanations have been given of the examples in each of which the reflection mechanism <NUM> is provided at the distal end of the optical fiber <NUM> in the optical fiber probe <NUM>. However, the reflection mechanism <NUM> may be provided between (in the middle of) the distal end and the proximal end of the optical fiber <NUM> in the optical fiber probe <NUM>. In this case, it is possible to determine whether or not a bent has occurred on the part of the optical fiber <NUM> beyond the position where the reflection mechanism <NUM> is provided.

Claim 1:
An optical fiber state detection system (<NUM>) comprising:
a first light source (<NUM>) that outputs a monitor-related light for monitoring a state of an optical fiber (<NUM>);
a reflection mechanism (<NUM>) that reflects the monitor-related light propagated through the optical fiber (<NUM>);
a light receiving part (<NUM>) that receives a reflected light reflected by the reflection mechanism (<NUM>);
a tap coupler (<NUM>) provided between the reflection mechanism (<NUM>) and both the first light source (<NUM>) and the light receiving part (<NUM>) such that the first light source (<NUM>) and the light receiving part (<NUM>) are connected the tap coupler (<NUM>);
a second light source (<NUM>) that outputs an ablation-related light;
a wave multiplexer (<NUM>) that multiplexes the monitor-related light and the ablation-related light; and
a control part (<NUM>),
wherein
the first light source (<NUM>) and the second light source (<NUM>) are connected to the wave multiplexer (<NUM>),
the wave multiplexer (<NUM>) and the light receiving part (<NUM>) are connected to the tap coupler (<NUM>),
the monitor-related light and the ablation-related light are different from each other in wavelength,
the reflection mechanism (<NUM>) transmits the ablation-related light,
when the control part (<NUM>) detects that a received optical power of the reflected light is greater than <NUM> and lower than a predetermined threshold value, the control part (<NUM>) shuts down the second light source (<NUM>), and
the monitor-related light and the ablation-related light are same as each other in beam shape.