JP2014137565A - Optical fiber scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To scan a designed trajectory with illumination light.SOLUTION: The optical fiber scanner 10 includes: a slender optical fiber 11 that can guide illumination light and emit it from the tip; and a piezoelectric device 15 that has a plate shape polarized in the thickness direction, and is bonded to an outer peripheral surface of the optical fiber 11 at the tip of the optical fiber 11 or a position containing the vicinity thereof in the direction in which the thickness direction crosses the longitudinal direction of the optical fiber 11.

Description

  The present invention relates to an optical fiber scanner.

  2. Description of the Related Art Conventionally, in the medical field, an optical fiber scanner that scans illumination light on a subject by emitting illumination light from the tip of the optical fiber while vibrating the optical fiber at high speed using a piezoelectric element is known. (For example, refer to Patent Document 1). The optical fiber scanner described in Patent Literature 1 includes a tube-shaped piezoelectric element (PZT tube), four electrodes arranged at equal intervals in the circumferential direction on the surface of the PZT tube, and light inserted into the PZT tube. The tip of the optical fiber is fixed to the PZT tube by a connecting member.

  In the optical fiber scanner described in Patent Document 1, when the PZT tube is bent and deformed, a force in the vertical direction acts on the optical fiber via the connecting member, and the optical fiber is bent and vibrated by this force. The bending vibration generated in two orthogonal directions in the optical fiber is synthesized in consideration of the amplitude and the phase, and the tip of the optical fiber is vibrated in a spiral shape to scan the illumination light two-dimensionally. Can do.

Special table 2008-504557 gazette

  However, the optical fiber scanner described in Patent Document 1 has a structure in which the force from the PZT tube acts on a position away from the tip of the optical fiber. Therefore, the tip of the optical fiber does not accurately follow the bending deformation of the PZT tube, and the vibration direction of the tip of the optical fiber is likely to be shaken. That is, the linear vibration becomes elliptical vibration, and there is a problem that the illumination light cannot be scanned accurately along the designed locus. In addition, there is a problem that it is difficult to realize ideal spiral vibration when attempting to vibrate the tip of the optical fiber by combining linear vibrations in two orthogonal directions.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an optical fiber scanner capable of scanning illumination light along a designed locus.

In order to achieve the above object, the present invention provides the following means.
The present invention has an elongated optical fiber capable of guiding illumination light and exiting from the tip, and a plate shape polarized in the thickness direction, and at the position including the tip of the optical fiber or the vicinity thereof. Provided is an optical fiber scanner comprising: a piezoelectric element attached to an outer peripheral surface of an optical fiber so that the thickness direction is in a direction crossing the longitudinal direction of the optical fiber.

  According to the present invention, when an alternating voltage is applied to the piezoelectric element in the thickness direction, the piezoelectric element expands and contracts in the direction orthogonal to the polarization direction, that is, the direction orthogonal to the thickness direction, so that the tip of the optical fiber is expanded. A bending vibration is excited such that the vibration vibrates in a direction crossing the longitudinal direction. Thereby, the illumination light emitted from the tip of the optical fiber can be scanned on the subject in accordance with the vibration of the tip.

  In this case, since the piezoelectric element is arranged at a position including or near the tip of the optical fiber, the tip of the optical fiber follows the expansion / contraction movement of the piezoelectric element accurately and is forced in a direction crossing the expansion / contraction direction. Vibrated. As a result, the tip of the optical fiber vibrates along the designed locus, so that the illumination light emitted from the tip of the optical fiber can be scanned along the designed locus.

In the above-described invention, a pair of the piezoelectric elements arranged opposite to each other in parallel may be provided with the optical fiber interposed in the radial direction.
By doing so, the bending vibration excited in the optical fiber can be increased by expanding and contracting the pair of piezoelectric elements in the same direction as compared with the case of only one piezoelectric element.

In the above invention, another pair of the above-described pair of piezoelectric elements arranged in parallel with each other with the optical fiber interposed therebetween at a position shifted by approximately 90 ° in the circumferential direction of the optical fiber with respect to the pair of piezoelectric elements. A piezoelectric element may be provided.
In this way, by applying an alternating voltage to each piezoelectric element with an appropriate phase shift, the tip of the optical fiber can be vibrated in a spiral shape, and illumination light can be scanned two-dimensionally. .

Moreover, in the said invention, you may provide the said 3 or more said piezoelectric element arranged in the circumferential direction of the said optical fiber.
In this way, by applying an alternating voltage to each piezoelectric element with an appropriate phase shift, the tip of the optical fiber can be vibrated in a spiral shape, and illumination light can be scanned two-dimensionally. .

  In the above invention, the piezoelectric element is disposed at a position retracted from the distal end of the optical fiber to the proximal end side of the optical fiber, and a distance between the distal end of the piezoelectric element and the distal end of the optical fiber. The frequency of the bending resonance vibration having one end as a fixed end of the tip portion of the optical fiber protruding to the tip side from the piezoelectric element is applied to the piezoelectric element to excite the bending vibration in the optical fiber. You may set so that it may become higher than the frequency of the alternating voltage supplied.

  By doing in this way, it can prevent that the front-end | tip of an optical fiber interferes with a surrounding member by not providing a piezoelectric element in the front-end | tip of an optical fiber with the largest amplitude. Further, the required accuracy such as the shape of the piezoelectric element and the positioning with respect to the optical fiber can be relaxed. Even if the piezoelectric element is disposed at a position retracted from the tip of the optical fiber, by setting the retracted amount within the above range, the tip of the optical fiber is not affected by the displacement of the position of the piezoelectric element. Can be vibrated.

  In the above invention, the piezoelectric element is disposed at a position protruding from the tip of the optical fiber toward the tip of the optical fiber, and the distance between the tip of the piezoelectric element and the tip of the optical fiber is In order to excite bending vibration in the optical fiber, the piezoelectric element has a frequency of bending resonance vibration whose one end is a fixed end of the tip portion of the piezoelectric element protruding to the tip side from the tip of the optical fiber. It may be set to be higher than the frequency of the alternating voltage supplied to.

  By doing so, it is possible to relax the required accuracy such as the shape of the piezoelectric element and the positioning with respect to the optical fiber. Even if the piezoelectric element is arranged at a position protruding from the tip of the optical fiber, by setting the protruding amount within the above range, the tip of the optical fiber is not affected by the displacement of the position of the piezoelectric element. Can be vibrated.

Moreover, in the said invention, you may provide the electroconductive electrode member arrange | positioned between the outer peripheral surface of the said optical fiber, and the said piezoelectric element.
By doing in this way, wiring of a GND line can be made easy by joining a GND line to this electrode member by making an electrode member into a GND electrode. In particular, in a configuration including a plurality of piezoelectric elements, it is possible to effectively facilitate the wiring of the GND line by using a common GND electrode as the electrode member.

In the above invention, the piezoelectric element may be a laminated piezoelectric element that is a laminated piezoelectric element in which a plurality of piezoelectric layers are laminated in the thickness direction.
By doing in this way, when the alternating voltage of the same magnitude | size is applied to a piezoelectric element, the displacement amount of expansion / contraction of a piezoelectric element can be increased, and the vibration amplitude of the front-end | tip of an optical fiber can be increased.

  According to the present invention, the illumination light can be scanned along a designed locus.

It is the perspective view which shows (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 1st Embodiment of this invention, and (c) the piezoelectric element of (a). (A) A side view for explaining the vibration operation in the X direction of the tip of the optical fiber of FIG. 1, and (b) a diagram showing a locus of vibration of the tip of the optical fiber of (a). It is (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 1st modification of the 1st Embodiment of this invention. It is the (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 2nd modification of the 1st Embodiment of this invention. It is the (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 3rd modification of the 1st Embodiment of this invention. It is (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 4th modification of the 1st Embodiment of this invention. It is (a) perspective view and (b) A-A 'sectional drawing which show schematic structure of the piezoelectric element with which the optical fiber scanner which concerns on the 5th modification of the 1st Embodiment of this invention is provided. It is the perspective view which shows (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 2nd Embodiment of this invention, and (c) and the piezoelectric element of (a). FIG. 9A is a side view for explaining the vibration operation in the X direction of the tip of the optical fiber in FIG. 8, and FIG. 9B is a diagram showing the locus of vibration at the tip of the optical fiber in FIG. It is (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the modification of the 2nd Embodiment of this invention. It is the perspective view which shows (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 3rd Embodiment of this invention, and (c) and the piezoelectric element of (a). FIG. 12A is a side view for explaining the vibration operation in the X direction of the tip of the optical fiber in FIG. 11 and FIG. FIG. 12A is a side view for explaining the vibration operation in the Y direction of the tip of the optical fiber in FIG. 11, and FIG. 12B is a diagram showing the locus of vibration at the tip of the optical fiber in FIG. It is a figure which shows the spiral locus | trajectory which the front-end | tip of the optical fiber of FIG. 11 draws. It is a figure which shows schematic structure of a scanning observation apparatus provided with the optical fiber scanner of FIG. It is (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 1st modification of the 3rd Embodiment of this invention. It is (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 2nd modification of the 3rd Embodiment of this invention. It is (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 3rd modification of the 3rd Embodiment of this invention. (A) Side view and (b) Front view showing schematic configuration of optical fiber scanner according to fourth modification of third embodiment of the present invention, and (c) Perspective view showing piezoelectric element of (a) It is. It is (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 5th modification of the 3rd Embodiment of this invention. It is (a) side view and (b) front view which show schematic structure of the optical fiber scanner which concerns on the 6th modification of the 3rd Embodiment of this invention.

(First embodiment)
An optical fiber scanner 10 according to a first embodiment of the present invention will be described below with reference to FIGS.
As shown in FIGS. 1A and 1B, an optical fiber scanner 10 according to this embodiment is provided on an elongated cylindrical optical fiber 11 made of a glass material and an outer peripheral surface of the optical fiber 11. A GND electrode (electrode member) 13, a single square plate-shaped piezoelectric element 15 attached to the outer peripheral surface of the optical fiber 11 via the GND electrode 13, and a midway position in the longitudinal direction of the optical fiber 11 are held. The holding member 17 is provided.

The optical fiber 11 can guide illumination light emitted from a light source (not shown) and emit it from the tip.
The GND electrode 13 is provided from the tip of the optical fiber 11 over a predetermined length in the longitudinal direction of the optical fiber 11 and over the entire circumference. The GND electrode 13 is formed, for example, by sputtering a metal such as gold on the outer peripheral surface of the optical fiber 11 or by applying a conductive silver paste on the outer peripheral surface of the optical fiber 11. The GND electrode 13 has a high hardness and a thickness of about several μm.

  The piezoelectric element 15 is made of lead zirconate titanate (PZT). In addition, as shown in FIG. 1C, the piezoelectric element 15 is provided with electrodes 16A and 16B on both surfaces facing each other in the thickness direction (hereinafter referred to as a front surface and a back surface), respectively, and a predetermined DC. The voltage is polarized in the thickness direction. The piezoelectric element 15 is affixed to the optical fiber 11 so that the thickness direction is directed to the radial direction of the optical fiber 11 and the position of the tip coincides with the position of the tip of the optical fiber 11.

  The back surface of the piezoelectric element 15 is bonded to the GND electrode 13 with an adhesive, and is attached to the outer peripheral surface of the optical fiber 11 over the entire length of the piezoelectric element 15. Specifically, an epoxy adhesive is thinly applied to the back surface of the piezoelectric element 15 and the surface of the GND electrode 13, the piezoelectric element 15 and the electrode 13 are aligned under a stereomicroscope, and then the piezoelectric element 15 is piezoelectrically bonded using a heat shrinkable tube. The piezoelectric element 15 is bonded to the GND electrode 13 by thermosetting the epoxy adhesive at a predetermined temperature while pressing the element 15 against the GND electrode 13. Note that the piezoelectric element 15 and the GND electrode 13 may be joined by a welding technique using solder or the like. By affixing the piezoelectric element 15 over its entire length, expansion and contraction over the entire length of the piezoelectric element 15 can be transmitted to the optical fiber 11 without waste.

  A lead wire 19 constituting an A phase for applying an alternating voltage to the piezoelectric element 15 is bonded to the surface of the piezoelectric element 15, that is, the surface opposite to the back surface bonded to the GND electrode 13 by a conductive adhesive. Has been. Further, a GND wire 21 for connecting the GND electrode 13 to the ground potential is joined to the GND electrode 13 by a conductive adhesive.

  The holding member 17 holds the position of the optical fiber 11 on the base end side with respect to the GND electrode 13 at a fixed position. Specifically, the holding member 17 is an annular member into which the optical fiber 11 is inserted, and the inner surface and the outer peripheral surface of the optical fiber 11 are joined by an adhesive. The holding member 17 is made of a metal such as stainless steel or ceramics having a relatively large specific gravity, and has a sufficiently large mass with respect to the distal end portion of the optical fiber 11 and the piezoelectric element 15 disposed on the distal end side of the holding member 17. Have.

Next, the operation of the optical fiber scanner 10 configured as described above will be described below.
In order to scan illumination light emitted from a light source on a subject by the optical fiber scanner 10 according to the present embodiment, first, the A phase of the piezoelectric element 15 corresponds to the frequency of the bending resonance vibration via the lead wire 19. Apply the alternating voltage.

  When an alternating voltage is applied to the piezoelectric element 15 in the thickness direction, the piezoelectric element 15 expands and contracts in a direction orthogonal to the polarization direction, that is, a direction orthogonal to the thickness direction. As a result, as shown in FIG. 2A, the tip of the optical fiber 11 vibrates in the direction (X direction) intersecting the longitudinal direction (Z direction) at the tip side of the holding member 17. Bending resonance vibration is excited. At this time, since the holding member 17 is sufficiently heavy with respect to the mass of the tip portion of the optical fiber 11, the optical fiber 11 is stably excited by the bending primary vibration having the vicinity of the tip of the holding member 17 as a fixed end. Is done.

  In this state, when the illumination light emitted from the light source is guided through the optical fiber 11 and emitted from the tip, as shown in FIG. 2B, in accordance with the linear vibration at the tip of the optical fiber 11. Illumination light can be reciprocated in the X direction on the subject. In FIG. 2B, the arrow S indicates the locus of the tip of the vibrating optical fiber 11.

  In this case, according to the optical fiber scanner 10 according to the present embodiment, the piezoelectric element 15 is directly bonded to the optical fiber 11 using an adhesive over a predetermined length from the tip of the optical fiber 11, thereby The expansion and contraction motion of the piezoelectric element 15 is directly transmitted to the tip of the fiber 11. Thereby, the tip of the optical fiber 11 is forcibly vibrated in the X direction according to the expansion and contraction motion of the piezoelectric element 15. As a result, the light emitted from the tip of the optical fiber 11 can be reciprocally scanned as designed along a linear locus in the X direction.

Furthermore, according to this embodiment, since the GND electrode 13 has a high hardness and a thickness of about several μm, the force transmitted from the piezoelectric element 15 to the optical fiber 11 is hardly attenuated at the GND electrode 13. Therefore, the optical fiber 11 can be flexibly vibrated efficiently.
Furthermore, according to this embodiment, by providing the GND electrode 13 between the optical fiber 11 and the piezoelectric element 15, it is necessary to draw out the GND line 21 from the electrode 16 </ b> B on the back surface of the piezoelectric element 15 bonded to the optical fiber 11. In addition, the GND line 21 can be drawn from an arbitrary position of the GND electrode 13. Therefore, the lead wire 19 and the GND wire 21 can be easily routed.

This embodiment can be modified as follows.
As a first modification, instead of disposing the GND electrode 13 between the optical fiber 11 and the piezoelectric element 15, as shown in FIGS. 3A and 3B, the outer peripheral surface of the optical fiber 11 is used. Alternatively, the electrode 16B on the back surface of the piezoelectric element 15 may be directly bonded, and the GND line 21 may be connected to the exposed position of the electrode 16B on the back surface using a conductive adhesive. That is, the electrode 16B on the back surface of the piezoelectric element 15 also serves as the GND electrode.
According to this modification, since it is not necessary to provide the GND electrode 13 separately, the configuration can be simplified.

As a second modification, as shown in FIGS. 4A and 4B, the piezoelectric element 15 may be provided over the entire length from the tip of the optical fiber 11 to the holding member 17 or the vicinity thereof.
According to the present modification, the force applied to the optical fiber 11 by the expanding and contracting piezoelectric element 15 can be further increased.

As a third modification, as shown in FIGS. 5A and 5B, a plurality of piezoelectric elements 15 of the second modification are provided in the longitudinal direction of the optical fiber 11 (two in the illustrated example). It may be divided.
According to this modification, a piezoelectric element with a short dimension can also be used effectively, and the design restrictions of the piezoelectric element to be used can be relaxed.

As a fourth modification, instead of forming the GND electrode 13 by coating the outer peripheral surface of the optical fiber 11 with a metal film, as shown in FIGS. 6 (a) and 6 (b), a cylinder made of metal. A micro tube (electrode member) 13 ′ may be used as the GND electrode. The material of the microtube 13 ′ is preferably nickel or copper.
According to this modification, it is not necessary to perform a process such as sputtering for forming a metal film on the outer peripheral surface of the optical fiber 11, so that manufacturing can be facilitated. Further, the GND line 21 can be joined to an arbitrary position of the microtube 13 ′, and the manufacturing can be facilitated.

As a fifth modification, as shown in FIGS. 7A and 7B, a plurality of (three in the illustrated example) thin piezoelectric sheets (piezoelectric layers) are used as the piezoelectric element 15 in the thickness direction. A laminated piezoelectric element laminated on each other may be used. FIG. 7A shows the appearance of the multilayer piezoelectric element 15, and FIG. 7B shows a cross section taken along the line AA 'in FIG. 7A. The piezoelectric sheet disposed inside has an internal electrode 16C, and an external electrode 16D is provided on the outer surface of the piezoelectric sheet.
According to this modification, a larger force can be generated when the same voltage is applied to the piezoelectric element 15.

(Second Embodiment)
Next, an optical fiber scanner 20 according to a second embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 8A and 8B, the optical fiber scanner 20 according to the present embodiment includes a pair of piezoelectric elements 15A disposed opposite to each other in parallel with the optical fiber 11 in the radial direction. It differs from the first embodiment in that it includes 15B.
In the following, portions having the same configuration as those of the optical fiber scanner 10 according to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The pair of piezoelectric elements 15 </ b> A and 15 </ b> B are bonded to the outer peripheral surface of the optical fiber 11 via the GND electrode 13 by an adhesive. Specifically, the back surface of one piezoelectric element 15 </ b> A is bonded to the GND electrode 13, and the front surface of the other piezoelectric element 15 </ b> B is bonded to the GND electrode 13. Therefore, the polarization directions of the piezoelectric element 15A and the piezoelectric element 15B are the same.

  Further, in the pair of piezoelectric elements 15A and 15B, lead wires 19A and 19B are bonded to the electrode 16A or 16B on the surface opposite to the surface bonded to the GND electrode 13 by a conductive adhesive. These two lead wires 19A and 19B are coupled to each other to constitute an A phase. In addition, one GND line 21 is bonded to the GND electrode 13 with a conductive adhesive.

  In the optical fiber scanner 20 according to the present embodiment, when an alternating voltage corresponding to the frequency of bending resonance vibration is applied to the A phase of the pair of piezoelectric elements 15A and 15B via the lead wires 19A and 19B, the piezoelectric elements 15A and 15B By expanding and contracting all at once in the direction orthogonal to the polarization direction, a bending resonance vibration in which the tip vibrates in a direction intersecting the longitudinal direction (Z direction) is excited in the optical fiber 11. Thereby, as shown by the arrow S in FIG. 9B, the tip of the optical fiber 11 can be vibrated in the X direction.

  As described above, according to the optical fiber scanner 20 according to the present embodiment, by using the two piezoelectric elements 15A and 15B, the optical fiber 11 is compared with the case where the single piezoelectric element 15 is used. The vibration amplitude to be excited can be increased.

The present embodiment can be modified as follows.
As in the first modification of the first embodiment, as shown in FIGS. 10A and 10B, the GND electrode 13 is omitted, and the pair of piezoelectric elements 15A and 15B are arranged on the outer periphery of the optical fiber 11. Each may be directly joined to the surface. For example, FIGS. 10A and 10B show a state in which the back surfaces of the piezoelectric elements 15A and 15B are joined to the outer peripheral surface of the optical fiber 11, respectively. The polarization directions (see arrows) of the piezoelectric elements 15A and 15B are different from each other, that is, directions toward the optical fiber 11, respectively.

In this case, for example, in one piezoelectric element 15A, the GND wire 21A is bonded to the electrode 16B on the surface (back surface) bonded to the optical fiber 11, and the lead wire 19A is connected to the electrode 16A on the opposite surface (front surface). Can be joined. In the other piezoelectric element 15B, the lead wire 19B is bonded to the electrode 16B on the surface (back surface) bonded to the optical fiber 11, and the GND wire 21B is bonded to the electrode 16A on the opposite surface (front surface). .
According to this modification, the configuration can be simplified by omitting the GND electrode 13.

  In the present embodiment and its modifications, the GND electrode 13 shown in the second to fourth modifications of the first embodiment may be employed, and the fifth modification of the first embodiment. The piezoelectric element 15 shown in FIG.

(Third embodiment)
Next, an optical fiber scanner 30 according to a third embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 11A and 11B, the optical fiber scanner 30 according to the present embodiment is other than the pair of piezoelectric elements 15 </ b> A and 15 </ b> B that are shifted in the circumferential direction of the optical fiber 11. This is different from the second embodiment in that it includes a pair of piezoelectric elements 15C and 15D.
In the following, portions having the same configuration as those of the optical fiber scanner 20 according to the second embodiment are denoted by the same reference numerals and description thereof is omitted.

  Like the pair of piezoelectric elements 15A and 15B, the pair of piezoelectric elements 15C and 15D are arranged to face each other in parallel with the optical fiber 11 in the radial direction, and are respectively attached to the outer peripheral surface of the optical fiber 11 by an adhesive. It is joined via the GND electrode 13. In the present embodiment, the back surface of the piezoelectric element 15 </ b> A and the surface of the piezoelectric element 15 </ b> B are bonded to the GND electrode 13, and the back surface of the piezoelectric element 15 </ b> C and the surface of the piezoelectric element 15 </ b> D are bonded to the GND electrode 13. Thereby, the polarization directions of the piezoelectric elements 15A and 15B are the same, and the polarization directions of the piezoelectric elements 15C and 15D are the same.

  Further, the pair of piezoelectric elements 15 </ b> A and 15 </ b> B and the pair of piezoelectric elements 15 </ b> C and 15 </ b> D are disposed so as to be shifted by 90 ° in the circumferential direction of the optical fiber 11. For example, the pair of piezoelectric elements 15A and 15B are disposed to face each other in the X direction, and the pair of piezoelectric elements 15C and 15D are disposed to face each other in the Y direction. These four piezoelectric elements 15A, 15B, 15C, and 15D each have a width dimension substantially equal to the diameter dimension of the optical fiber 11.

  In the pair of piezoelectric elements 15A and 15B, the driving leads 19A and 19B constituting the A phase are respectively provided on the electrode 16A or 16B on the surface opposite to the surface bonded to the GND electrode 13, and the conductive adhesive. Are joined by. In the pair of piezoelectric elements 15C and 15D, driving lead wires 19C and 19D constituting the B phase are bonded to the electrode 16A or 16B opposite to the surface bonded to the GND electrode 13 by a conductive adhesive. Has been. A GND line 21 provided in common to the four piezoelectric elements 15A, 15B, 15C, and 15D is joined to the GND electrode 13 by a conductive adhesive.

Next, the operation of the optical fiber scanner 30 configured as described above will be described.
In the optical fiber scanner 30 according to the present embodiment, when an alternating voltage corresponding to the frequency of bending resonance vibration is applied to the A phase of the pair of piezoelectric elements 15A and 15B via the lead wires 19A and 19B, the piezoelectric elements 15A and 15B. Are simultaneously expanded and contracted in a direction orthogonal to the polarization direction, whereby the bending resonance vibration is excited in the optical fiber 11 as shown in FIG. In this bending resonance vibration, the vicinity of the proximal end of the piezoelectric elements 15A and 15B becomes a node, and the tip of the optical fiber 11 becomes an antinode. Thereby, as indicated by an arrow Sx in FIG. 12B, the tip of the optical fiber 11 can be linearly vibrated in the X direction.

  On the other hand, when an alternating voltage corresponding to the frequency of bending resonance vibration is applied in the thickness direction to the B phase of the pair of piezoelectric elements 15C and 15D via the lead wires 19C and 19D, the piezoelectric elements 15C and 15D are orthogonal to the polarization direction. By expanding and contracting all at once in the direction, bending resonance vibration is excited in the optical fiber 11 as shown in FIG. In this bending resonance vibration, the vicinity of the proximal end of the piezoelectric elements 15C and 15D becomes a node, and the tip of the optical fiber 11 becomes an antinode. Thereby, as indicated by an arrow Sy in FIG. 13B, the tip of the optical fiber 11 can be linearly vibrated in the Y direction.

  Here, when alternating voltages whose phases are shifted by π / 2 are simultaneously applied to the piezoelectric elements 15A and 15B and the piezoelectric elements 15C and 15D, the tip of the optical fiber 11 vibrates along a circular locus. Further, when the amplitudes of the two alternating voltages at this time are changed with time in a sine wave shape, the tip of the optical fiber 11 vibrates along a spiral locus as shown in FIG. Thereby, the illumination light can be scanned two-dimensionally along the spiral trajectory on the subject.

  In this case, according to the present embodiment, since the piezoelectric elements 15A, 15B, 15C, and 15D are also arranged at the tip of the optical fiber 11, the tip of the optical fiber 11 is the piezoelectric element 15A, 15B, 15C, and 15D. It can be forced to vibrate in the X and Y directions following the telescopic motion accurately. As a result, the tip of the optical fiber 11 is vibrated along a designed spiral trajectory, and as a result, the illumination light can be two-dimensionally scanned on the subject X along the designed spiral trajectory. .

  Next, a case where the optical fiber scanner 30 according to the present embodiment is employed in a scanning observation apparatus will be described. FIG. 15 shows a part of the configuration of the scanning observation apparatus including the fiber scanner 30. This scanning observation apparatus includes a lens 2 disposed on the front end side of the optical fiber scanner 30 and a plurality of detection fibers 4 arranged in the circumferential direction outside the optical fiber 11.

  As shown in FIG. 15, when the tip of the optical fiber 11 is vibrated spirally with the lens 2 facing the subject X, and the illumination light L propagated in the optical fiber 11 is emitted from the tip, The illumination light L is converged by the lens 2 and applied to the subject X, and is scanned two-dimensionally on the subject X.

  The reflected light L ′ from the subject X irradiated with the illumination light L is detected by a plurality of detection fibers 4. The scanning observation apparatus can image the surface state of the scanning range of the illumination light L in the subject X by detecting the reflected light L ′ by the detection fiber 4 in synchronization with the scanning cycle of the illumination light L. . In this case, according to the present embodiment, the illumination light L is scanned on the subject X along the ideal spiral trajectory as designed, so that an image with no distortion can be obtained. .

This embodiment can be modified as follows.
As a first modification, instead of providing four piezoelectric elements 15A, 15B, 15C, 15D, two piezoelectric elements 15A, 15C are provided as shown in FIGS. You may have. The piezoelectric elements 15 </ b> A and 15 </ b> C are arranged at positions shifted by 90 ° in the circumferential direction of the optical fiber 11 so that the polarization directions are orthogonal to each other.

  According to this modification, by applying an alternating voltage to the two piezoelectric elements 15A and 15C with a phase shifted by π / 2, the tip of the optical fiber 11 is vibrated in a spiral shape, so The illumination light can be scanned two-dimensionally. Therefore, the configuration can be simplified as compared with the case where the four piezoelectric elements 15A, 15B, 15C, and 15D are used.

  As a second modification, as shown in FIGS. 17A and 17B, the width dimensions of the piezoelectric elements 15A, 15B, 15C, and 15D may be larger than the diameter dimensions of the optical fiber 11, respectively. . In this case, as shown in the figure, the optical fiber 11 is arranged so that the front surfaces or back surfaces and side surfaces of the piezoelectric elements 15A, 15B, 15C, and 15D adjacent in the circumferential direction of the optical fiber 11 are alternately in contact with each other. The piezoelectric elements 15A, 15B, 15C, and 15D may be joined with a slight shift in the width direction.

  According to this modification, the substantial volume of the piezoelectric elements 15A, 15B, 15C, and 15D increases, so that more energy is input and the displacement amount of each piezoelectric element 15A, 15B, 15C, and 15D is changed. The amplitude of the optical fiber 11 can be increased by increasing it.

  As a third modification, as shown in FIGS. 18A and 18B, the three piezoelectric elements 15A, 15B, and 15C are arranged by being shifted by 120 ° in the circumferential direction of the optical fiber 11 and bonded. May be. In this case, the piezoelectric elements 15A, 15B, and 15C are bonded to the GND electrode 13 on the back surface thereof with the polarization direction directed to the optical fiber 11. Further, driving leads 19A, A, B, and C, respectively, are formed on the electrode 16A on the surface (surface) opposite to the surface bonded to the GND electrode 13 of the piezoelectric elements 15A, 15B, 15C. 17B and 17C are joined by a conductive adhesive.

  Then, by applying an alternating voltage that is electrically shifted in phase by 120 ° to the A phase of the piezoelectric element 15A, the B phase of the piezoelectric element 15B, and the C phase of the piezoelectric element 15C, the number of piezoelectric elements is reduced to four. The tip of the optical fiber 11 can be vibrated in a spiral shape while reducing the number from one to three, and the illumination light can be scanned two-dimensionally on the subject.

  As a fourth modified example, as shown in FIGS. 19A and 19B, a cylindrical piezoelectric element 15E may be used. The cylindrical piezoelectric element 15 </ b> E has an inner diameter that is substantially the same as the outer diameter of the optical fiber 11. Four electrodes 16A arranged substantially evenly in the circumferential direction are provided on the outer peripheral surface of the piezoelectric element 15E. An electrode 16B is uniformly provided on the inner peripheral surface of the piezoelectric element 15E.

  According to this modification, even when the piezoelectric element 15E made of a single member is used, the tip of the optical fiber 11 is attached as in the case where the four piezoelectric elements 15A, 15B, 15C, and 15D are provided separately. It can be vibrated in a spiral shape. Further, assembling can be facilitated by configuring the piezoelectric element 15E from a single member.

  As a fifth modified example, as shown in FIGS. 20A and 20B, the distal ends of the piezoelectric elements 15A, 15B, 15C, and 15D are retracted by a distance L from the distal end of the optical fiber 11 to the proximal end side. You may arrange in a position. However, this distance L is such that the resonance frequency of the primary bending vibration mode in which the one end of the distal end portion of the optical fiber 11 having a length L, which protrudes from the piezoelectric elements 15A, 15B, 15C, and 15D, is fixed. It is set in a range higher than the frequency of the alternating voltage for exciting the optical fiber 11 to bend resonance vibration.

  When the distance L is in the above range, when an alternating voltage is applied to cause the optical fiber 11 to bend and vibrate, the portions of the optical fiber 11 that protrude from the piezoelectric elements 15A, 15B, 15C, and 15D are bent. Resonance vibration is not affected, and the tip of the optical fiber 11 follows a spiral locus as designed, as in the case where the piezoelectric elements 15A, 15B, 15C, and 15D are arranged as shown in FIG. Vibrate.

  According to this modification, by not providing the piezoelectric elements 15A, 15B, 15C, and 15D at the tip of the optical fiber 11 having the largest amplitude, the optical fiber scanner 30 can be connected to other members disposed around, for example, Interference with the detection fiber 4 of FIG. 15 can be prevented. In addition, it is possible to relax the design restrictions of the piezoelectric elements 15A, 15B, 15C, and 15D to be used and the positional accuracy required during assembly.

  As a sixth modified example, as shown in FIGS. 21A and 21B, the tips of the piezoelectric elements 15A, 15B, 15C, and 15D are projected to the tip side by a distance M from the tip of the optical fiber 11. You may arrange. However, this distance M is the resonance frequency of the primary bending vibration mode in which the one end of the tip of the piezoelectric element 15A, 15B, 15C, 15D of length M protruding from the tip of the optical fiber 11 is fixed. The frequency is set to be higher than the frequency of the alternating voltage for exciting the bending resonance vibration in the optical fiber 11.

When the distance M is in the above range, when the optical fiber 11 is subjected to bending resonance vibration by applying an alternating voltage, the portions of the piezoelectric elements 15A, 15B, 15C, and 15D protruding from the optical fiber 11 are bent. Resonance vibration is not affected, and the tip of the optical fiber 11 follows a spiral locus as designed, as in the case where the piezoelectric elements 15A, 15B, 15C, and 15D are arranged as shown in FIG. Vibrate.
According to this modification, it is possible to relax the design restrictions and positional accuracy required during assembly of the piezoelectric elements 15A, 15B, 15C, and 15D to be used.

  Further, in the present embodiment and its modifications, the GND electrode 13 shown in the first to fourth modifications of the first embodiment may be adopted, and the fifth modification of the first embodiment is adopted. The illustrated piezoelectric element may be employed.

10, 20, 30 Optical fiber scanner 11 Optical fiber 13 GND electrode (electrode member)
15, 15A, 15B, 15C, 15D, 15E Piezoelectric element

Claims (8)

An elongated optical fiber that can guide the illumination light and emit it from the tip,
It has a plate shape that is polarized in the thickness direction, and in a direction that intersects the longitudinal direction of the optical fiber on the outer peripheral surface of the optical fiber at a position that includes the tip of the optical fiber or its vicinity. An optical fiber scanner comprising a piezoelectric element attached to face.   The optical fiber scanner according to claim 1, further comprising a pair of the piezoelectric elements disposed to face each other in parallel with the optical fiber sandwiched in a radial direction.   3. Another pair of the piezoelectric elements disposed opposite to each other in parallel with the optical fiber interposed therebetween at a position shifted by approximately 90 ° in the circumferential direction of the optical fiber with respect to the pair of piezoelectric elements. An optical fiber scanner described in 1.   The optical fiber scanner according to claim 1, further comprising three or more piezoelectric elements arranged in a circumferential direction of the optical fiber. The piezoelectric element is disposed at a position retracted from the distal end of the optical fiber to the proximal end side of the optical fiber,
The distance between the tip of the piezoelectric element and the tip of the optical fiber is determined by the frequency of bending resonance vibration with one end as a fixed end of the tip portion of the optical fiber protruding to the tip side of the piezoelectric element. The optical fiber scanner according to any one of claims 1 to 4, wherein the optical fiber scanner is set to be higher than a frequency of an alternating voltage supplied to the piezoelectric element in order to excite bending vibration in the optical fiber. The piezoelectric element is arranged at a position protruding from the tip of the optical fiber to the tip side of the optical fiber,
The distance between the tip of the piezoelectric element and the tip of the optical fiber is the bending resonance vibration with one end of the tip of the piezoelectric element protruding to the tip side of the tip of the optical fiber as a fixed end. The optical fiber according to any one of claims 1 to 4, wherein the frequency is set to be higher than a frequency of an alternating voltage supplied to the piezoelectric element in order to excite bending vibration in the optical fiber. Scanner.   The optical fiber scanner according to claim 1, further comprising a conductive electrode member disposed between an outer peripheral surface of the optical fiber and the piezoelectric element.   8. The optical fiber scanner according to claim 1, wherein the piezoelectric element is a stacked piezoelectric element in which a plurality of piezoelectric layers are stacked in a thickness direction.

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