OPTICAL FIBER SCANNER, ILLUMINATION DEVICE, AND OBSERVATION DEVICE

An optical fiber scanner includes an optical fiber and a fixed member that is fixed to the outer periphery of the optical fiber. The fixed member is provided with: two vibration parts that are adjacent to the optical fiber in radial directions of the optical fiber that intersect with each other and that expand and contract in the longitudinal direction of the optical fiber; and a connector that connects the two vibration parts. The two vibration parts respectively have inner surfaces that abut against the outer periphery of the optical fiber.

TECHNICAL FIELD

The present invention relates to an optical fiber scanner, an illumination device, and an observation device.

BACKGROUND ART

In the related art, there is a known optical fiber scanner that is provided with an optical fiber and piezoelectric elements fixed to the outer periphery of the optical fiber and in which the optical fiber is made to undergo a bending vibration through expansion and contraction of the piezoelectric elements, thus scanning light emitted from the distal end of the optical fiber (for example, see PTL 1). In order to two-dimensionally scan the light, it is necessary to produce a bending vibration in the optical fiber in two axial directions perpendicular to each other (X-direction and Y-direction). Thus, in the optical fiber scanner of PTL 1, the X-direction piezoelectric elements and the Y-direction piezoelectric elements are disposed at positions shifted by 90 degrees in the circumferential direction of the optical fiber.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

An object of the present invention is to provide an optical fiber scanner capable of obtaining stable scanning performance by improving assembly accuracy, and an illumination device and an observation device that are provided with the same.

Solution to Problem

According to a first aspect, the present invention provides an optical fiber scanner including: an optical fiber that has a longitudinal axis and that emits light from a distal end portion thereof; and a fixed member that is fixed to an outer periphery of the optical fiber at a position closer to a base end portion of the optical fiber than to the distal end portion thereof, wherein the fixed member is provided with: a first vibration part that is adjacent to the optical fiber in a first radial direction of the optical fiber and that expands and contracts in the longitudinal direction of the optical fiber when a voltage is applied thereto; a second vibration part that is adjacent to the optical fiber in a second radial direction of the optical fiber, the second radial direction intersecting with the first radial direction, and that expands and contracts in the longitudinal direction of the optical fiber when a voltage is applied thereto; and a connector that connects the first vibration part and the second vibration part; the first vibration part has a first inner surface that abuts against the outer periphery of the optical fiber; and the second vibration part has a second inner surface that is disposed at an angle with respect to the first inner surface and that abuts against the outer periphery of the optical fiber.

In the above-described first aspect, at least one part of the connector may have a higher vibration absorption than the vibration absorption of the first vibration part and the second vibration part.

In the above-described first aspect, it is preferable that an outer part of the connector that is located on the opposite side from the optical fiber have a higher vibration absorption than the vibration absorption of the first vibration part and the second vibration part.

In the above-described first aspect, the fixed member may have a third inner surface that is provided at the opposite side of the optical fiber from the first inner surface and that is brought into contact with the outer periphery of the optical fiber.

The above-described first aspect may further include a third vibration part that is provided at the opposite side of the optical fiber from the first vibration part and that expands and contracts in the longitudinal direction of the optical fiber when a voltage is applied thereto, wherein the third vibration part may have the third inner surface.

In the above-described first aspect, the fixed member may be open, in the second radial direction, at the opposite side of the optical fiber from the second inner surface.

In the above-described first aspect, the first inner surface and the third inner surface may have a larger size than the radius of the optical fiber in the second radial direction; and an opening of the fixed member on the opposite side of the optical fiber from the second inner surface may have a larger size than the diameter of the optical fiber in the direction perpendicular to the second radial direction.

In the above-described first aspect, the size of the second vibration part in the second radial direction may be larger than the sizes of the first vibration part and the third vibration part in the first radial direction.

In the above-described first aspect, the fixed member may include: a first fixed member that is provided with the first vibration part, the second vibration part, and the connector; and a second fixed member that is provided with a fourth vibration part having a fourth inner surface that is provided at the opposite side of the optical fiber from the second inner surface and that is brought into contact with the outer periphery of the optical fiber; and the first fixed member and the second fixed member may be disposed adjacent to each other in the circumferential direction around the longitudinal axis and may be assembled into a tube shape surrounding the outer periphery of the optical fiber, in a close contact state.

In the above-described first aspect, the fixed member may include: a first fixed member that is provided with the first vibration part, the second vibration part, and the connector; and a second fixed member that is provided with: a third vibration part having a third inner surface that is provided at the opposite side of the optical fiber from the first inner surface and that is brought into contact with the outer periphery of the optical fiber; a fourth vibration part having a fourth inner surface that is provided at the opposite side of the optical fiber from the second inner surface and that is brought into contact with the outer periphery of the optical fiber; and a second connector that connects the third vibration part and the fourth vibration part; and the first fixed member and the second fixed member may be adjacent to each other in the circumferential direction around the longitudinal axis and may be assembled into a tube shape surrounding the outer periphery of the optical fiber, in a close contact state.

In the above-described first aspect, the first fixed member and the second fixed member may have, at both ends thereof in the circumferential direction, chamfered parts that at least partially extend along the longitudinal direction; and the first fixed member and the second fixed member may be assembled in a close contact state such that the chamfered parts are brought into close contact with each other.

In the above-described first aspect, a metal coating for coating the outer periphery of the optical fiber from the base end of the optical fiber to a section thereof in the vicinity of the distal end of the fixed member may be provided on the outer periphery of the optical fiber.

In the above-described first aspect, the optical fiber may have a square-prism shape having side surfaces in the first radial direction and the second radial direction.

According to a second aspect, the present invention provides an illumination device including: a light source that produces illumination light; and an optical fiber scanner according to the first aspect, in which the base end of the optical fiber is connected to the light source.

According to a third aspect, the present invention provides an observation device including: an illumination device according to the second aspect; a light detector that detects return light returning from an object when the object is irradiated with illumination light from the illumination device; and a voltage supplyer that supplies the voltage to the first vibration part and the second vibration part of the fixed member.

DESCRIPTION OF EMBODIMENTS

First Embodiment

An optical fiber scanner1, an illumination device10, and an observation device100according to a first embodiment of the present invention will be described below with reference toFIGS. 1 to 8.

As shown inFIG. 1, the observation device100of this embodiment is provided with: an endoscope20that has an elongated insertion portion20a; a control device body30that is connected to the endoscope20; and a display40that is connected to the control device body30. The observation device100is an optical-scanning-type endoscope device that scans illumination light emitted from the distal end of the insertion portion20aof the endoscope20, on an object A along a spiral scanning trajectory B, and that acquires an image of the object A.

As shown inFIG. 2, the observation device100is further provided with: the illumination device10, which radiates illumination light onto the object A; a light detector60, such as a photodiode, that detects return light returning from the object A when the object A is irradiated with the illumination light; and a drive control device (voltage supplyer)70that drivingly controls the illumination device10and the light detector60. The light detector60and the drive control device70are provided in the control device body30.

The illumination device10is provided with: a light source50that is provided in the control device body30and that produces illumination light; the optical fiber scanner1, which is provided in the insertion portion20aand which has an illumination optical fiber2that guides the illumination light produced by the light source50and that emits the illumination light from the distal end thereof; a focusing lens11that is disposed closer to the distal end than the optical fiber2is and that focuses the illumination light emitted from the optical fiber2; an elongated tubular frame12that accommodates the optical fiber scanner1and the focusing lens11; and a plurality of detection optical fibers13that are provided on the outer periphery of the frame12in an arranged manner in the circumferential direction and that guide return light (for example, reflected light of the illumination light or fluorescence) from the object A to the light detector60.

As shown inFIGS. 2 and 3, the optical fiber scanner1is provided with: the optical fiber2; a fixed member3that is fixed to the outer periphery of the optical fiber2; and a fixing part4that is provided on the optical fiber2at a position closer to the base end than the fixed member3is and that fixes the optical fiber2to the frame12.

The optical fiber2is a multi-mode fiber or a single-mode fiber and is made of a cylindrical glass material having a longitudinal axis. The optical fiber2is disposed along the longitudinal direction of the frame12and extends from the base end of the frame12to the control device body30. The distal end of the optical fiber2is disposed, inside the frame12, in the vicinity of a distal end portion, and the base end of the optical fiber2is connected to the light source50in the control device body30.

The fixed member3is provided on the outer periphery of the optical fiber2at a position closer to the base end of the optical fiber2than to the distal end of the optical fiber2, and a distal end section (hereinafter, referred to as “protrusion”)2aof the optical fiber2protrudes from a distal-end surface of the fixed member3. Hereinafter, the longitudinal direction of the optical fiber2is referred to as the Z-direction, and two radial directions of the optical fiber2that are perpendicular to each other are referred to as the X-direction (first radial direction) and the Y-direction (second radial direction).

As shown inFIGS. 3 and 4, the cross-sectional shape of the fixed member3in an XY-plane is an L-shape in which two flat inner surfaces51aand52athat are perpendicular to each other are brought into contact with the cylindrical outer periphery of the optical fiber2. The two inner surfaces51aand52aand the outer periphery of the optical fiber2are fixed with an adhesive agent. The fixed member3is made of an entirely-homogeneous piezoelectric material (for example, lead zirconate titanate) and has a seamless integral structure. The fixed member3is manufactured by being cut out from a prismatic piezoelectric material, for example.

The fixed member3is composed of: a first vibration part51that is adjacent to the optical fiber2in the X-direction; a second vibration part52that is adjacent to the optical fiber2in the Y-direction; and a connector6that connects the first vibration part51and the second vibration part52. The connector6is provided between an end of the first vibration part51that is located close to the second vibration part52and an end of the second vibration part52that is located close to the first vibration part51.

The distal end and the base end of the fixed member3are open in the Z-direction. The fixed member3is open at the opposite sides of the optical fiber2from the first vibration part51and the second vibration part52in the X-direction and the Y-direction, respectively. Therefore, in the assembly process of the optical fiber2and the fixed member3, the optical fiber2is brought toward the inner surfaces51aand52ain a radial direction, thus being made to abut against the inner surfaces51aand52a.

The first vibration part51has: the flat first inner surface51a, against which the outer periphery of the optical fiber2is made to abut; and a first outer surface51bthat is located closer to an outer side than the first inner surface51ais in the X-direction and that is opposed to the first inner surface51a. The first inner surface51ais disposed parallel to the Z-direction, along a tangent to the outer periphery of the optical fiber2in the Y-direction. Electrodes71aand71bare formed on the first inner surface51aand the first outer surface51b, respectively, and the piezoelectric material is polarized in the X-direction in a region between the first inner surface51aand the first outer surface51b. Accordingly, a first piezoelectrically active region51cthat expands and contracts in the Z-direction through application of a voltage between the electrodes71aand71bis formed between the first inner surface51aand the first outer surface51b. Arrows P in the figure indicate polarization directions of the piezoelectric material.

The second vibration part52has: the flat second inner surface52a, against which the outer periphery of the optical fiber2is made to abut; and a second outer surface52bthat is located closer to an outer side than the second inner surface52ais in the Y-direction and that is opposed to the second inner surface52a. The second inner surface52ais disposed parallel to the Z-direction, along a tangent to the outer periphery of the optical fiber2in the X-direction. Electrodes72aand72bare formed on the second inner surface52aand the second outer surface52b, respectively, and the piezoelectric material is polarized in the Y-direction in a region between the second inner surface52aand the second outer surface52b. Accordingly, a second piezoelectrically active region52cthat expands and contracts in the Z-direction through application of a voltage between the electrodes72aand72bis formed between the second inner surface52aand the second outer surface52b.

The electrodes71aand71bof the first vibration part51are each disposed across the central axis of the optical fiber2in the Y-direction. It is preferable that the electrodes71aand71beach be disposed such that the sizes thereof on both sides of the central axis of the optical fiber2become equal.

The electrodes72aand72bof the second vibration part52are each disposed across the central axis of the optical fiber2in the X-direction. It is preferable that the electrodes72aand72beach be disposed such that the sizes thereof on both sides of the central axis of the optical fiber2become equal.

A phase-A lead8A is connected to the electrode71b, a phase-B lead8B is connected to the electrode72b, and a GND lead8G is connected to the electrode71aor the electrode72a. The leads8A,8B, and8G are connected to the drive control device70in the control device body30. A conductive adhesive agent or solder is used for the connections between the electrodes71a,71b,72a, and72band the leads8A,8B, and8G.

Although the electrodes71aand72a, shown inFIGS. 3 and 4, are formed on the entire inner surfaces51aand52a, respectively, and are connected to each other, instead of this, as shown inFIG. 5, the electrodes71aand72amay be formed only on partial sections of the inner surfaces51aand52a, respectively, and may be separated from each other. In this case, GND leads8G are each connected to the electrode71aand the electrode72a. The electrodes71band72b, which are formed on the outer surfaces51band52b, may also be formed only on partial sections of the outer surfaces51band52b, as shown inFIG. 5.

The fixing part4is formed of a cylindrical member and is provided on the radially outer side of the optical fiber2. The inner periphery of the fixing part4is fixed to the outer periphery of the optical fiber2by means of an adhesive agent, and the outer periphery of the fixing part4is fixed to an inner wall of the frame12. Accordingly, the optical fiber2is supported by the fixing part4in a cantilevered manner, in which the distal end thereof is a free end.

The drive control device70applies a phase-A alternating voltage having a predetermined driving frequency to the electrode71bvia the phase-A lead8A and applies a phase-B alternating voltage having the predetermined driving frequency to the electrode72bvia the phase-B lead8B. The predetermined driving frequency is set to the same frequency as the natural frequency of the protrusion2aof the optical fiber2or to a frequency close to the natural frequency. Here, the drive control device70supplies the phase-A alternating voltage and the phase-B alternating voltage, whose phases differ from each other by π/2 and whose amplitudes temporarily vary in a sinusoidal manner, to the phase-A lead8A and the phase-B lead8B, respectively.

Next, the operation of the thus-configured optical fiber scanner1, the illumination device10, and the observation device100will be described.

In order to observe the object A by using the observation device100of this embodiment, the drive control device70is actuated to cause illumination light to be supplied from the light source50to the optical fiber2and to cause the alternating voltages, having the predetermined driving frequency, to be applied to the electrodes71band72bvia the leads8A and8B.

When the phase-A alternating voltage is supplied to the electrode71b, and the voltage is applied to the first piezoelectrically active region51cin the X-direction, the first piezoelectrically active region51cundergoes a stretching vibration in the Z-direction perpendicular to the polarization direction, thus exciting, at the protrusion2aof the optical fiber2, an X-direction bending vibration in which the position of the fixing part4serves as a node, and the distal end of the optical fiber2serves as an antinode, and thus making the distal end of the optical fiber2vibrate in the X-direction. Accordingly, illumination light emitted from the distal end of the optical fiber2is linearly scanned in the X-direction.

When the phase-B alternating voltage is supplied to the electrode72b, and the alternating voltage is applied to the second piezoelectrically active region52cin the Y-direction, the second piezoelectrically active region52cundergoes a stretching vibration in the Z-direction perpendicular to the polarization direction, thus exciting, at the protrusion2aof the optical fiber2, a Y-direction bending vibration in which the position of the fixing part4serves as a node, and the distal end of the optical fiber2serves as an antinode, and thus making the distal end of the optical fiber2vibrate in the Y-direction. Accordingly, illumination light emitted from the distal end of the optical fiber2is linearly scanned in the Y-direction.

Here, the phase of the phase-A alternating voltage and the phase of the phase-B alternating voltage are shifted from each other by π/2, and the amplitudes of the phase-A alternating voltage and the phase-B alternating voltage temporarily vary in a sinusoidal manner, thereby causing the distal end of the optical fiber2to vibrate along a spiral trajectory and two-dimensionally scanning illumination light on the object A along the spiral trajectory. Because the driving frequency is equivalent to the natural frequency of the protrusion2aor is a frequency close thereto, the protrusion2acan be efficiently excited.

Return light from the object A is received by the plurality of optical fibers13, and the intensity thereof is detected by the light detector60. The drive control device70causes the light detector60to detect the return light in synchronization with the scanning period of the illumination light and associates the intensity of the detected return light with the scanning position of the illumination light, thereby generating an image of the object A. The generated image is output from the control device body30to the display40and is displayed on the display40.

Here, an assembly method for the optical fiber scanner1will be described.

In order to assemble the optical fiber scanner1of this embodiment, an adhesive agent is applied to the first inner surface51aand the second inner surface52aof the fixed member3. Next, the relative positions of the optical fiber2and the fixed member3are set so as to make the outer periphery of the optical fiber2abut against both the first inner surface51aand the second inner surface52a. Next, the adhesive agent is hardened, thus fixing the fixed member3to the outer periphery of the optical fiber2. Accordingly, the optical fiber2and the fixed member3can be assembled.

In this case, according to this embodiment, the two vibration parts51and52, which cause the optical fiber2to undergo a bending vibration in the X-direction and the Y-direction, are sections of the fixed member3, which is formed of a single member. Specifically, the relative positions of the first vibration part51and the second vibration part52are fixed. The outer periphery of the optical fiber2is made to abut against the two inner surfaces51aand52aof the fixed member3, which are perpendicular to each other, thereby positioning the optical fiber2at a predetermined position with respect to the fixed member3. Therefore, the relative positions of the first vibration part51, the second vibration part52, and the optical fiber2can be uniquely set. Accordingly, there is an advantage in that it is possible to improve the assembly accuracy of the optical fiber scanner1and to stably manufacture the optical fiber scanner1having a desired scanning performance.

In this embodiment, although the fixed member3is formed of a seamless integral structure, instead of this, it is also possible to join three blocks that constitute the first vibration part51, the second vibration part52, and the connector6, thereby forming a fixed member3that is formed of a single member as a whole.

In this embodiment, although the whole connector6is made of a piezoelectric material, instead of this, as shown inFIGS. 6 and 7, at least a part of the connector6may be constituted of a vibration absorbing member9that has a higher vibration absorption than at least one of the first vibration part51and the second vibration part52. In the example shown inFIG. 6, only a part of the connector6is constituted of the vibration absorbing member9. In the example shown inFIG. 7, the whole connector6is constituted of the vibration absorbing member9.

By doing so, it is possible to suppress transmission of vibrations between the first piezoelectrically active region51cand the second piezoelectrically active region52c. It is preferable that the material of the vibration absorbing member9be hard resin, for example, PEEK, engineering plastic, or elastomer.

As shown inFIG. 6, when the vibration absorbing member9is provided only partially on the connector6, it is preferable that the vibration absorbing member9be provided on an outer part of the connector6that is located on the opposite side from the optical fiber2. By doing so, it is possible to facilitate machining of the connector6.

In this embodiment, although the single fixed member3is provided, instead of this, as shown inFIG. 8, it is also possible to further provide another fixed member (second fixed member)301that is disposed adjacent to the fixed member (first fixed member)3in the circumferential direction so as to form a square tube surrounding the optical fiber2together with the fixed member3.

As in the first fixed member3, the second fixed member301has, in an XY-plane, an L-shape in cross-section in which two flat inner surfaces53aand54athat are perpendicular to each other are brought into contact with the outer periphery of the optical fiber2.

The second fixed member301is composed of: a third vibration part53that is adjacent to the optical fiber2in the X-direction at the opposite side from the first vibration part51; a fourth vibration part54that is adjacent to the optical fiber2in the Y-direction at the opposite side from the second vibration part52; and a connector (second connector)601that connects the third vibration part53and the fourth vibration part54.

The third vibration part53has the same structure as the first vibration part51. Specifically, the third vibration part53has a flat third inner surface53athat is opposed to the first inner surface51awith the optical fiber2sandwiched therebetween in an X radial direction and that is made to abut against the outer periphery of the optical fiber2. An electrode73ato which another GND lead8G is connected is formed on the inner surface53aof the third vibration part53. An electrode73bto which another phase-A lead8A is connected is formed on an outer surface53bof the third vibration part53. Accordingly, a third piezoelectrically active region53cthat expands and contracts in the Z-direction is formed between the inner surface53aand the outer surface53b.

The fourth vibration part54has the same structure as the second vibration part52. Specifically, the fourth vibration part54has a flat fourth inner surface54athat is opposed to the second inner surface52awith the optical fiber2sandwiched therebetween in a Y radial direction and that is made to abut against the outer periphery of the optical fiber2. An electrode74athat is connected to the electrode73ais formed on the inner surface54aof the fourth vibration part54. An electrode74bto which another phase-B lead8B is connected is formed on an outer surface54bof the fourth vibration part54. Accordingly, a fourth piezoelectrically active region54cthat expands and contracts in the Z-direction is formed between the inner surface54aand the outer surface54b.

In the assembly process of the optical fiber scanner, the relative positions of the optical fiber2and the first fixed member3are set so as to make the outer periphery of the optical fiber2abut against the first and second inner surfaces51aand52a. Then, the second fixed member301is positioned with respect to the first fixed member3and the optical fiber2so as to make the third and fourth inner surfaces53aand54aabut against the outer periphery of the optical fiber2. At this time, the shapes of both end sections of the second fixed member301in the circumferential direction are designed such that the end section of the first vibration part51and the end section of the fourth vibration part54, which are adjacent in the circumferential direction, are brought into close contact with each other, and the end section of the second vibration part52and the end section of the third vibration part53, which are adjacent in the circumferential direction, are brought into close contact with each other. Next, the adhesive agent is hardened, thereby fixing the fixed members3and301to the outer periphery of the optical fiber2.

According to this modification, the optical fiber2can be protected by the fixed members3and301, which cover the outer periphery of the optical fiber2over the entire circumference. The optical fiber2is made to vibrate through stretching vibrations of the two piezoelectrically active regions51cand53cin the X-direction and the two piezoelectrically active regions52cand54cin the Y-direction, thereby making it possible to obtain a larger vibration amplitude.

Second Embodiment

Next, an optical fiber scanner101, an illumination device, and an observation device according to a second embodiment of the present invention will be described with reference toFIGS. 9 to 12. In this embodiment, a description will be mainly given of configurations different from those in the first embodiment, identical signs will be assigned to the configurations common to those in the first embodiment, and a description thereof will be omitted.

As shown inFIGS. 9 and 10, the optical fiber scanner101of this embodiment differs from that of the first embodiment in that a fixed member31further has: a third vibration part53that is adjacent to the optical fiber2in the X-direction at the opposite side from the first vibration part51; and another connector61that connects the third vibration part53and the second vibration part52.

The connector61is provided between an end section of the third vibration part53that is located close to the second vibration part52and an end section of the second vibration part52that is located close to the third vibration part53. Therefore, the cross-sectional shape of the fixed member31in an XY-plane is a U-shape having two right-angled corners, and the fixed member31is open on the opposite side of the optical fiber2from the second vibration part52. The fixed member31is made of an entirely-homogeneous piezoelectric material (for example, lead zirconate titanate) and has a seamless integral structure. The fixed member31is manufactured by being cut out from a prismatic piezoelectric material, for example.

The third vibration part53has: a flat third inner surface53athat abuts against the outer periphery of the optical fiber2; and a third outer surface53bthat is located closer to an outer side than the third inner surface53ais in the X-direction and that is opposed to the third inner surface53a. Therefore, the optical fiber2is disposed in a space surrounded by the three inner surfaces51a,52a, and53a, and the outer periphery of the optical fiber2is supported by the inner surfaces51a,52a, and53aat three points that are shifted by 90 degrees in the circumferential direction.

The width dimension W, in the X-direction, of the opening on the opposite side of the optical fiber2from the second vibration part52is equal to or larger than the diameter of the optical fiber2. Therefore, in the assembly process of the optical fiber scanner101, the optical fiber2can be inserted, in a radial direction, into the space surrounded by the three inner surfaces51a,52a, and53a.

The third inner surface53ais disposed parallel to the Z-direction, along a tangent to the outer periphery of the optical fiber2in the Y-direction. The height dimension H of each of the first inner surface51aand the third inner surface53ain the Y-direction is larger than the radius of the optical fiber2such that the central axis of the optical fiber2is located in the space surrounded by the three inner surfaces51a,52a, and53a.

Electrodes73aand73bare formed on the third inner surface53aand the third outer surface53b, respectively, and the piezoelectric material is polarized in the X-direction in a region between the third inner surface53aand the third outer surface53b. Accordingly, a third piezoelectrically active region53cthat expands and contracts in the Z-direction through application of a voltage between the electrodes73aand73bis formed between the third inner surface53aand the third outer surface53b. The electrodes73aand73bare each disposed across the central axis of the optical fiber2in the Y-direction. It is preferred that the electrodes73aand73beach be disposed such that the sizes thereof on both sides of the central axis of the optical fiber2become equal. As in the electrodes71a,72a,71b, and72b, which are shown inFIG. 5, the electrodes73aand73bmay also be formed only on partial sections of the inner surface53aand the outer surface53b, respectively.

Another phase-A lead8A is connected to the electrode73b. The drive control device70applies a phase-A alternating voltage to the electrode73bvia the phase-A lead8A. Here, the polarization direction of the first piezoelectrically active region51cand the polarization direction of the third piezoelectrically active region53care directed in the same side in the X-direction. Therefore, when phase-A alternating voltages are simultaneously applied to the electrode71band the electrode73b, one of the first piezoelectrically active region51cand the third piezoelectrically active region53ccontracts in the Z-direction, and the other expands in the Z-direction, thereby exciting an X-direction bending vibration at the protrusion2aof the optical fiber2.

The thickness dimension of each of the first and third piezoelectrically active regions51cand53cin the X-direction (i.e., the distance between the electrodes71aand71band the distance between the electrodes73aand73b) and the thickness dimension of the second piezoelectrically active region52cin the Y-direction (i.e., the distance between the electrodes72aand72b) are equal to each other. The drive control device70supplies, to the electrode72b, a phase-B alternating voltage that is two times larger than a phase-A alternating voltage. Accordingly, the amplitude of the X-direction bending vibration due to the first vibration part51and the third vibration part53and the amplitude of the Y-direction bending vibration due to the second vibration part52are equal to each other, thus forming the entire light scanning trajectory into a perfectly circular shape.

In order to assemble the optical fiber scanner101, an adhesive agent is applied to the first inner surface51a, the second inner surface52a, and the third inner surface53aof the fixed member31. Next, the optical fiber2is inserted, in a radial direction, into the space surrounded by the three inner surfaces51a,52a, and53a, and the relative positions of the optical fiber2and the fixed member31are set so as to make the outer periphery of the optical fiber2abut against all of the first inner surface51a, the second inner surface52a, and the third inner surface53a. Next, the adhesive agent is hardened, thus fixing the fixed member31to the outer periphery of the optical fiber2. Accordingly, the optical fiber2and the fixed member31can be assembled.

In this case, according to this embodiment, the three vibration parts51,52, and53, which cause the optical fiber2to undergo the bending vibration in the X-direction and the Y-direction, are sections of the fixed member31, which is formed of a single member. Specifically, the relative positions of the first vibration part51, the second vibration part52, and the third vibration part53are fixed. The outer periphery of the optical fiber2is made to abut against the three inner surfaces51a,52a, and53aof the fixed member31, thereby positioning the optical fiber2at a predetermined position with respect to the fixed member31. Therefore, the relative positions of the first vibration part51, the second vibration part52, the third vibration part53, and the optical fiber2can be uniquely set. Accordingly, there is an advantage in that it is possible to improve the assembly accuracy of the optical fiber scanner101and to stably manufacture the optical fiber scanner101having a desired scanning performance.

In this embodiment, although the thickness dimensions of the three piezoelectrically active regions51c,52c, and53care made equal, instead of this, as shown inFIG. 11, the second piezoelectrically active region52cmay have a larger thickness dimension than the first and third piezoelectrically active regions51cand53c.

By doing so, because the resonant frequency of a bending vibration of the protrusion2ain the X-direction and the resonant frequency of a bending vibration thereof in the Y-direction become close to each other, it is possible to cause the protrusion2ato stably undergo the bending vibrations and to obtain a more stable scanning trajectory B.

In a case in which the second piezoelectrically active region52chas a thickness dimension that is two times larger than each of those of the first and third piezoelectrically active regions51cand53c, when the magnitudes of phase-A and phase-B alternating voltages are equal, the amplitudes of bending vibrations of the protrusion2ain the X-direction and the Y-direction are equal. Specifically, alternating voltages having equal magnitudes can be supplied to all of the electrodes71b,72b, and73b, thus making it easy to control the alternating voltages.

In this embodiment, a support member that is made of a material other than the piezoelectric material may be provided instead of the third vibration part53. In this case, the support member has an inner surface (third inner surface) that is brought into contact with the outer periphery of the optical fiber2, such that the outer periphery of the optical fiber2is supported by the fixed member31at three points in the circumferential direction.

In this embodiment, the connector6,61may also be provided with the vibration absorbing member9, such as that shown inFIG. 6 or 7.

In this embodiment, although the single fixed member31is provided, instead of this, as shown inFIG. 12, it is also possible to further provide another fixed member (second fixed member)311that is disposed adjacent to the fixed member (first fixed member)31in the circumferential direction, so as to form a square tube for surrounding the optical fiber2together with the fixed member31.

The second fixed member311is provided with a fourth vibration part54that has a flat-plate shape in which a flat inner surface54ais brought into contact with the outer periphery of the optical fiber2and that is adjacent to the optical fiber2in the Y-direction at the opposite side from the second vibration part52.

The fourth vibration part54has the same structure as the fourth vibration part54that is described in the first embodiment and that is shown inFIG. 8. Specifically, the fourth vibration part54of this modification has the flat fourth inner surface54athat is opposed to the second inner surface52awith the optical fiber2sandwiched therebetween in the Y-radial direction, and a fourth piezoelectrically active region54cthat expands and contracts in the Z-direction is formed between the inner surface54aand an outer surface54b.

In the assembly process of the optical fiber scanner, after the relative positions of the optical fiber2and the first fixed member31are set such that the outer periphery of the optical fiber2abuts against the first, second, and third inner surfaces51a,52a, and53a. Then, the second fixed member311is positioned with respect to the first fixed member31and the optical fiber2such that the fourth inner surface54aabuts against the outer periphery of the optical fiber2. At this time, the shapes of both end sections of the second fixed member311are designed such that the end section of the first vibration part51and the end section of the fourth vibration part54, which are adjacent in the circumferential direction, are brought into close contact with each other, and the end section of the third vibration part53and the end section of the fourth vibration part54, which are adjacent in the circumferential direction, are brought into close contact with each other. Next, an adhesive agent is hardened, thereby fixing the fixed members31and311to the outer periphery of the optical fiber2.

According to this modification, the optical fiber2can be protected by the fixed members3and311, which cover the outer periphery of the optical fiber2over the entire circumference. The optical fiber2is made to vibrate through stretching vibrations of the two piezoelectrically active regions51cand53cin the X-direction and the two piezoelectrically active regions52cand54cin the Y-direction, thereby making it possible to obtain a larger vibration amplitude.

In the above-described first and second embodiments, it is also possible to use an optical fiber2whose outer periphery is coated with a metal coating from the base end thereof to a section thereof in the vicinity of the distal end of the fixed member3,31.

By doing so, a suitable solder for precise joining can be used to join the optical fiber2and the inner surface51a,52a,53aof the fixed member3,31, thus making it possible to further improve the assembly accuracy of the optical fiber scanner1,101. The optical fiber2can be protected by the metal coating, thus making it possible to prevent the optical fiber2from being damaged during assembly. Because the electrode71a,72a,73aon the inner surface51a,52a,53ais electrically connected to the fixing part4via the metal coating, a single GND lead8G is connected to the fixing part4, instead of the electrode71a,72a,73a, thereby making it possible to cause the fixing part4to function as a common GND electrode. Accordingly, there is an advantage in that the wiring operation for the lead8G can be facilitated.

In the above-described first and second embodiments, when the two fixed members3and301shown inFIG. 8, which form a square tube, are provided or when the two fixed members31and311shown inFIG. 12, which form a square tube, are provided, it is also possible to provide chamfers14and15at the end sections of the respective fixed members3and301in the circumferential direction, as shown inFIG. 13.

The chamfers14and15are formed so as to be brought into close contact with each other when the first fixed member3and the second fixed member301are assembled into a square tube shape.FIG. 13shows the flat chamfers14and15. The chamfers14and15may each have a concavo-convex shape or a curved surface. The chamfers14and15may be formed over the entire lengths of the fixed members3and301in the longitudinal direction or may be formed only over partial lengths thereof in the longitudinal direction.

By providing the chamfers14and15in this way, the two fixed members3and301can be easily assembled so as to be in close contact with each other.

In the above-described first and second embodiments, although the optical fiber2is cylindrical, instead of this, as shown inFIG. 13, it is also possible to use a square-prism-shaped optical fiber21that has two side surfaces opposed in the X-direction and two side surfaces opposed in the Y-direction. The optical fiber21is positioned with respect to the fixed member such that at least two side surfaces thereof abut against the two inner surfaces51aand52aof the fixed member. AlthoughFIG. 13shows an example combination of the square-prism-shaped optical fiber21and the two fixed members3and301, it is also possible to combine the optical fiber21with any of the above-described fixed members.

In this way, by using the square-prism-shaped optical fiber21, the vibration of the optical fiber2in the X-direction and the vibration thereof in the Y-direction can be reliably separated from each other.

As a result, the following aspects are derived from the above-described embodiments.

According to a first aspect, the present invention provides an optical fiber scanner including: an optical fiber that has a longitudinal axis and that emits light from a distal end portion thereof; and a fixed member that is fixed to an outer periphery of the optical fiber at a position closer to a base end portion of the optical fiber than to the distal end portion thereof, wherein the fixed member is provided with: a first vibration part that is adjacent to the optical fiber in a first radial direction of the optical fiber and that expands and contracts in the longitudinal direction of the optical fiber when a voltage is applied thereto; a second vibration part that is adjacent to the optical fiber in a second radial direction of the optical fiber, the second radial direction intersecting with the first radial direction, and that expands and contracts in the longitudinal direction of the optical fiber when a voltage is applied thereto; and a connector that connects the first vibration part and the second vibration part; the first vibration part has a first inner surface that abuts against the outer periphery of the optical fiber; and the second vibration part has a second inner surface that is disposed at an angle with respect to the first inner surface and that abuts against the outer periphery of the optical fiber.

According to the first aspect of the present invention, when a voltage is applied to the first vibration part, the first vibration part is deformed in the longitudinal direction of the optical fiber, thereby causing bending deformation of the optical fiber in the first radial direction and causing the distal end of the optical fiber to be displaced in the first radial direction. Accordingly, light emitted from the distal end of the optical fiber is scanned in the first radial direction. Similarly, when a voltage is applied to the second vibration part, the second vibration part is deformed in the longitudinal direction of the optical fiber, thereby causing bending deformation of the optical fiber in the second radial direction and causing the distal end of the optical fiber to be displaced in the second radial direction. Accordingly, light emitted from the distal end of the optical fiber is scanned in the second radial direction, which intersects with the first radial direction. Therefore, voltages are simultaneously applied to the first vibration part and the second vibration part, thereby making it possible to two-dimensionally scan the light.

In this case, because the first vibration part and the second vibration part are respectively formed as sections of the fixed member, which is formed of a single member, the relative positions of the first vibration part and the second vibration part are fixed. In the assembly process of the optical fiber scanner, the outer periphery of the optical fiber is made to abut against the first inner surface and the second inner surface, which form an angle, in radial directions, thereby positioning the optical fiber at a predetermined position with respect to the fixed member. Therefore, the relative positions of the three parts, i.e., the first vibration part, the second vibration part, and the optical fiber, are uniquely set. Accordingly, the assembly accuracy of the optical fiber scanner is improved, thus making it possible to obtain stable scanning performance.

In the above-described first aspect, at least one part of the connector may have a higher vibration absorption than the vibration absorption of the first vibration part and the second vibration part.

By doing so, because vibrations are absorbed at the connector between the first vibration part and the second vibration part, it is possible to prevent stretching vibrations from being transferred between the first vibration part and the second vibration part.

In the above-described first aspect, it is preferable that an outer part of the connector that is located on the opposite side from the optical fiber have a higher vibration absorption than the vibration absorption of the first vibration part and the second vibration part.

By doing so, when the vibration absorption of the connector is enhanced by using a different material from that of the first vibration part and the second vibration part, it is possible to facilitate machining of the connector.

In the above-described first aspect, the fixed member may have a third inner surface that is provided at the opposite side of the optical fiber from the first inner surface and that is brought into contact with the outer periphery of the optical fiber.

By doing so, in the assembly process of the optical fiber scanner, the optical fiber can be inserted, from an opening in a radial direction, into the space surrounded by the first inner surface, the second inner surface, and the third inner surface. The outer periphery of the optical fiber is supported by the three inner surfaces at three points that are at different positions in the circumferential direction, thereby making it possible to stably hold the optical fiber.

The above-described first aspect may further include a third vibration part that is provided at the opposite side of the optical fiber from the first vibration part and that expands and contracts in the longitudinal direction of the optical fiber when a voltage is applied thereto, wherein the third vibration part may have the third inner surface.

By doing so, it is possible to give a stronger deforming force to the optical fiber in the first radial direction by means of the first and third vibration parts.

In the above-described first aspect, the fixed member may be open, in the second radial direction, at the opposite side of the optical fiber from the second inner surface.

In the above-described first aspect, the first inner surface and the third inner surface may have a larger size than the radius of the optical fiber in the second radial direction; and an opening of the fixed member on the opposite side of the optical fiber from the second inner surface may have a larger size than the diameter of the optical fiber in the direction perpendicular to the second radial direction.

By doing so, the optical fiber can be easily inserted from the opening. The optical fiber can be disposed such that the central axis of the optical fiber is positioned in the space surrounded by the three inner surfaces.

In the above-described first aspect, the size of the second vibration part in the second radial direction may be larger than the sizes of the first vibration part and the third vibration part in the first radial direction.

By doing so, the resonant frequency of a bending vibration of the optical fiber in the first radial direction and the resonant frequency of a bending vibration of the optical fiber in the second radial direction become close to each other. Therefore, when the optical fiber is made to undergo a bending vibration by applying alternating voltages to the three vibration parts, the bending vibrations of the optical fiber can be made more stable.

In the above-described first aspect, the fixed member may include: a first fixed member that is provided with the first vibration part, the second vibration part, and the connector; and a second fixed member that is provided with a fourth vibration part having a fourth inner surface that is provided at the opposite side of the optical fiber from the second inner surface and that is brought into contact with the outer periphery of the optical fiber; and the first fixed member and the second fixed member may be disposed adjacent to each other in the circumferential direction around the longitudinal axis and may be assembled into a tube shape surrounding the outer periphery of the optical fiber, in a close contact state.

By doing so, in the assembly process of the optical fiber scanner, after the outer periphery of the optical fiber is made to abut against the first inner surface and the second inner surface of the first fixed member and is positioned, the second fixed member can be attached to the first fixed member such that the first fixed member and the second fixed member form a tube. The outer periphery of the optical fiber is supported by the four inner surfaces at four points that are at different positions in the circumferential direction, thereby making it possible to more stably hold the optical fiber.

In the above-described first aspect, the fixed member may include: a first fixed member that is provided with the first vibration part, the second vibration part, and the connector; and a second fixed member that is provided with: a third vibration part having a third inner surface that is provided at the opposite side of the optical fiber from the first inner surface and that is brought into contact with the outer periphery of the optical fiber; a fourth vibration part having a fourth inner surface that is provided at the opposite side of the optical fiber from the second inner surface and that is brought into contact with the outer periphery of the optical fiber; and a second connector that connects the third vibration part and the fourth vibration part; and the first fixed member and the second fixed member may be adjacent to each other in the circumferential direction around the longitudinal axis and may be assembled into a tube shape surrounding the outer periphery of the optical fiber, in a close contact state.

By doing so, in the assembly process of the optical fiber scanner, after the outer periphery of the optical fiber is made to abut against the first inner surface and the second inner surface of the first fixed member and is positioned, the second fixed member can be attached to the first fixed member such that the first fixed member and the second fixed member form a tube. The outer periphery of the optical fiber is supported by the four inner surfaces at four points that are at different positions in the circumferential direction, thereby making it possible to more stably hold the optical fiber.

In the above-described first aspect, the first fixed member and the second fixed member may have, at both ends thereof in the circumferential direction, chamfers that at least partially extend along the longitudinal direction; and the first fixed member and the second fixed member may be assembled in a close contact state such that the chamfers are brought into close contact with each other.

By doing so, it is possible to easily assemble the first fixed member and the second fixed member so as to bring them into close contact with each other.

In the above-described first aspect, a metal coating for coating the outer periphery of the optical fiber from the base end of the optical fiber to a section thereof in the vicinity of the distal end of the fixed member may be provided on the outer periphery of the optical fiber.

By doing so, because a suitable solder for precise joining can be used to join the fixed member and the optical fiber, the assembly accuracy can be further improved. The optical fiber can be protected by a metal coating. Because another member that is electrically connected to the respective vibration parts via the optical fiber can be used as a ground (GND) electrode, it is not necessary to directly connect a GND lead to the fixed member, and wiring of the lead can be facilitated.

In the above-described first aspect, the optical fiber may have a square-prism shape having side surfaces in the first radial direction and the second radial direction.

By doing so, a vibration of the optical fiber in the first radial direction and a vibration thereof in the second radial direction can be reliably separated from each other.

According to a second aspect, the present invention provides an illumination device including: a light source that produces illumination light; and an optical fiber scanner according to the first aspect, in which the base end of the optical fiber is connected to the light source.

According to a third aspect, the present invention provides an observation device including: an illumination device according to the second aspect; a light detector that detects return light returning from an object when the object is irradiated with illumination light from the illumination device; and a voltage supplyer that supplies the voltage to the first vibration part and the second vibration part of the fixed member.

REFERENCE SIGNS LIST