WO2020044528A1 - Optical fiber scanner, lighting device and observation device - Google Patents

Abstract

This optical fiber scanner (1) comprises: an optical fiber (2) through which illumination light is guided and from the tip (2a) of which the illumination light is emitted; and an oscillation part (3) that causes the tip (2a) of the optical fiber (2) to oscillate in a direction intersecting the long axis of the optical fiber (2). The oscillation part (3) comprises: a flat-plate-shaped elastic body (4) that holds the optical fiber (2) which traverses therethrough in the plate thickness direction; and, on at least one of the end surfaces of the elastic body (4) in the plate thickness direction, an electromechanical conversion element (5) that can expand and contract in at least three directions intersecting with the long axis.

Description

Optical fiber scanner, illumination device and observation device

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

There is known an optical fiber scanner that scans illumination light by vibrating the tip of an optical fiber that guides illumination light in a direction orthogonal to the longitudinal direction by vibration of a piezoelectric element (for example, see Patent Document 1). In the optical fiber scanner disclosed in Patent Document 1, an elongated rectangular flat plate-type piezoelectric element is attached to four side surfaces of an elongated prismatic ferrule having a through hole through which an optical fiber passes. The vibration of the piezoelectric element is transmitted to the optical fiber via the prism ferrule, and vibrates the tip of the optical fiber in a direction orthogonal to the longitudinal direction.

JP-A-2015-94158

However, the optical fiber scanner of Patent Document 1 utilizes the expansion and contraction of the piezoelectric element in the longitudinal direction to vibrate the optical fiber. For this reason, it is necessary to make the length of the driving unit including the prismatic ferrule and the piezoelectric elements attached to the four side surfaces thereof sufficiently long so that the optical fiber can sufficiently oscillate.
Therefore, an object of the present invention is to provide an optical fiber scanner, an illumination device, and an observation device that can easily be shortened.

One embodiment of the present invention includes an optical fiber that guides illumination light and emits the illumination light from a distal end, and a vibration unit that vibrates the distal end of the optical fiber in a direction that intersects a longitudinal axis of the optical fiber. The vibrating portion is provided on at least one of a flat elastic body that holds the optical fiber in a state where the optical fiber penetrates in the thickness direction, and at least one end surface of the elastic body in the thickness direction, and at least intersects the longitudinal axis. An optical fiber scanner including an electromechanical transducer that can expand and contract in three directions.

According to this aspect, when a voltage is applied to the electromechanical transducer, the electromechanical transducer is deformed to vibrate according to the voltage waveform, and the vibration of the electromechanical transducer is transmitted to the optical fiber via the elastic body. The tip of the optical fiber is vibrated in at least three directions crossing the longitudinal axis of the optical fiber. Thus, when the illumination light guided by the optical fiber is emitted, the tip of the optical fiber is vibrated so as to optically scan, thereby causing the emitted illumination light to scan the object to be illuminated. Can be.

That is, the elastic body is formed in a flat plate shape, the optical fiber is penetrated in the thickness direction of the elastic body, and the electromechanical transducer is arranged on any surface of the elastic body. An optical fiber scanner whose dimensions are easily shortened can be constructed.

According to another aspect of the present invention, a light source that generates illumination light, any one of the above-described optical fiber scanners having a base end of the optical fiber connected to the light source, and a voltage is supplied to the electromechanical transducer. And a voltage supply unit.

Another aspect of the present invention is an observation apparatus including the illumination device, and a light detection unit that detects return light returning from the subject by irradiating the illumination light from the illumination device to the subject. is there.

According to the present invention, it is possible to provide an optical fiber scanner, an illumination device, and an observation device that can be easily shortened.

It is a longitudinal section showing an observation device concerning one embodiment of the present invention. FIG. 2 is a perspective view illustrating an optical fiber scanner provided in the observation device in FIG. 1. FIG. 3 is a front view illustrating an example of electrode arrangement in a piezoelectric element of the optical fiber scanner of FIG. 2. FIG. 3 is a diagram illustrating an example of vibration of an optical fiber by the optical fiber scanner of FIG. 2. FIG. 5 is a diagram illustrating an example of vibration of an optical fiber by the same optical fiber scanner as in FIG. 4. FIG. 13 is a front view showing a modification of the electrode arrangement example of FIG. 2 and showing a case where the electrodes are arranged while being equally divided into three parts in the circumferential direction. FIG. 10 is a front view showing a modification of the electrode arrangement example of FIG. 2 and showing a case where the electrodes are arranged unequally divided into three in the circumferential direction. FIG. 8 is a front view showing a modification of the polarization direction in the electrode arrangement of FIG. 7. FIG. 8 is a front view showing a modification of the polarization direction in the electrode arrangement of FIG. 7. FIG. 8 is a front view showing a modification of the polarization direction in the electrode arrangement of FIG. 7. It is a longitudinal cross-sectional view which shows the modification of the observation device of FIG. It is a longitudinal cross-sectional view which shows the modification of the observation device of FIG.

An optical fiber scanner 1, an illumination device 10, and an observation device 100 according to an embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the observation device 100 according to the present embodiment includes an illumination device 10 that irradiates illumination light to a subject, and a light detection unit 60 that detects return light returning from the object when the illumination light is emitted. And

The illuminating device 10 includes a light source 50 that generates illumination light, an optical fiber scanner 1 having an illumination optical fiber 2 that guides illumination light emitted from the light source 50 and emits the light from the distal end, and an optical fiber 2. The light-emitting device includes a condenser lens 11 disposed on the distal end side for condensing illumination light emitted from the optical fiber 2, and an elongated cylindrical rigid frame 12 for housing the optical fiber scanner 1 and the condenser lens 11. I have. In addition, the lighting device 10 includes a voltage supply unit (not shown) that supplies a voltage to the piezoelectric element 5 described later.

The light detection unit 60 is provided on the outer peripheral surface of the frame body 12 of the lighting device 10 in a circumferential direction and is provided with a plurality of detection devices that guide return light (for example, reflected light of illumination light or fluorescence) from a subject. And a photodetector 14 for detecting return light guided by the detection optical fiber 13.

As shown in FIGS. 1 and 2, the optical fiber scanner 1 according to the present embodiment includes an optical fiber 2 that emits guided light from the tip and an optical fiber 2 that is a free end that can swing. A vibrating section 3 for vibrating the distal end 2 a in a direction intersecting the longitudinal axis of the optical fiber 2. The vibrating part 3 has a disc-shaped elastic body 4 for holding the optical fiber 2 in a state of penetrating in the thickness direction, and an end face around the longitudinal axis of the optical fiber 2 and the base end side of the elastic body 4 in the thickness direction. And a piezoelectric element (electromechanical conversion element) 5 arranged.

The elastic body 4 has a through hole 4a through which the optical fiber 2 passes at the position of the center of gravity. The elastic body 4 is made of, for example, a metal material such as nickel or copper or a ceramic material such as zirconia, and is formed of a flexible elastic member that is hard to suppress vibration such as urethane resin or felt over the entire inner surface of the frame 12. It is fixed so that it can vibrate. The optical fiber 2 is held in a cantilever state by the elastic body 4 on the inner wall of the through hole 4a by an adhesive or the like.
The elastic body 4 is provided with a cylindrical protrusion 6 extending the through hole 4 a in a direction along the longitudinal axis, integrally with the elastic body 4. The optical fiber 2 is inserted into a through hole 4a extending inside the elastic body 4 and the convex portion 6, and is securely held.

The piezoelectric element 5 is formed in an arc shape with a central angle of 90 °, and has a uniform size (the same thickness and size) so as not to overlap four locations around the axis of the through hole 4a of the elastic body 4 so as not to overlap. They are arranged side by side. Here, the piezoelectric element 5 is adhered to the elastic body 4 by bonding with an adhesive.

The piezoelectric elements 5 disposed on both sides of the optical fiber 2 are polarized in different directions with respect to four positions around the axis of the through hole 4a. 8 are arranged. The electrode 7 on the end face on the elastic body 4 side is a common electrode. Thus, as shown in FIG. 3, when the same voltage is supplied to the electrodes 7, 8 of the piezoelectric element 5 disposed on both sides of the optical fiber 2, as shown in FIGS. 4 and 5, The one piezoelectric element 5 expands so that the diameter of the elastic body 4 increases, and the other piezoelectric element 5 contracts so that the diameter of the elastic body 4 decreases. Here, since the arrangement of the electrodes 7 and 8 provided on the piezoelectric element 5 is equally divided, the forces generated by the individual piezoelectric elements 5 are equalized, and the vibration trajectory of the tip 2a of the optical fiber 2 is easily controlled. be able to.

This causes bending vibration in which the piezoelectric elements 5 on both sides of the optical fiber 2 are bent in the direction opposite to the thickness direction. By changing the phase of the voltage supplied to the electrodes 7 of the adjacent piezoelectric elements 5 by 90 °, the tip 2a, which is the free end of the optical fiber 2, can be rotated in a cantilever state.

That is, with the bending vibration in which the piezoelectric elements 5 on both sides of the optical fiber 2 are bent in the direction opposite to the thickness direction, the radial direction around the longitudinal axis of the optical fiber 2 which is the central axis of the disc-shaped elastic body 4 That is, it is elastically deformed asymmetrically in a direction intersecting the longitudinal axis. By generating this elastic deformation in at least three directions orthogonal to the longitudinal axis of the optical fiber 2, the optical fiber 2 swings in a cantilever state, that is, the tip end 2a of the optical fiber 2 is turned by so-called whirling bending vibration. be able to. Here, the tip 2a of the optical fiber 2 is optically scanned on a plane orthogonal to the longitudinal axis of the optical fiber 2 by changing the amplitude of the voltage supplied to the electrodes 7 and 8 for driving the piezoelectric element 5. Can be vibrated as follows.

For example, the voltage amplitude is set such that the tip 2a of the optical fiber 2 is orthogonal to each other, and an alternating voltage whose amplitude gradually changes between 0 and a maximum value at a constant frequency is applied to each of the electrodes 7, 8. By applying the voltage, the spiral scanning can be performed on the subject irradiated with the light emitted from the optical fiber 2. In addition, by applying an AC voltage having a different frequency and a constant amplitude between the electrodes 7 and 8 which are adjacent to each other in the circumferential direction of the elastic body 4, so-called Lissajous scanning or raster scanning can be performed.

The operation of the optical fiber scanner 1, the illuminating device 10, and the observation device 100 according to the present embodiment configured as described above will be described below.
According to the optical fiber scanner 1 according to the present embodiment, the elastic body 4 that transmits the vibration of the piezoelectric element 5 to the optical fiber 2 is formed in a flat plate shape that penetrates the optical fiber 2 in the thickness direction. The elastic body 4 is attached to the end face in the thickness direction. Thereby, it is easy to greatly reduce the length dimension as compared with the case where the optical fiber 2 is made to penetrate the conventional elongated columnar elastic body along the axial direction, and the frame 12 is greatly reduced. There is an advantage that the length can be reduced. In addition, by reducing the length of the elastic body 4, the area in which the vibration reaches in the longitudinal direction of the frame body 12 is also reduced, so that the influence of the vibration on the optical system inside the optical fiber scanner 1 is also reduced.

According to the illumination device 10 and the observation device 100 including the optical fiber scanner 1, when the illumination device 10 and the observation device 100 are attached to the distal end of the flexible insertion portion and inserted into the body of a patient for use, the rigid portion becomes a hard portion. There is an advantage that the length of the optical fiber scanner 1 can be kept short and the insertion portion can be easily curved in accordance with the shape of the body cavity of the patient. Therefore, the illumination device 10 and the observation device 100 including the optical fiber scanner 1 according to the present embodiment are suitable for being used inside an object having an elongated and meandering shape like a blood vessel.

Then, light emitted from the light source 50 is incident on the base end of the optical fiber 2, and the voltage applied to the piezoelectric element 5 is vibrated to vibrate the tip 2 a of the optical fiber 2 in a helical manner. The light guided and emitted from the tip 2a of the optical fiber 2 can be spirally operated on the subject. The return light returning from the subject as a result of the irradiation of the light from the optical fiber 2 is received by the detection optical fibers 13 arranged on the outer periphery of the frame 12 and is detected by the photodetector 14 connected to the optical fiber 2. Is detected.

Thus, an image of the subject can be generated by storing the scanning position of the light emitted from the distal end 2a of the optical fiber 2 and the intensity of the light detected by the photodetector 14 in association with each other.

In the present embodiment, the piezoelectric element 5 divided into four in the circumferential direction of the longitudinal axis is arranged on at least one of the end faces in the plate thickness direction of the elastic body 4, but instead of this, as shown in FIG. In addition, the piezoelectric element 5 may be divided into three or more. In the case of FIG. 6, the three piezoelectric elements 5 are arranged in three equally divided areas. Instead, as shown in FIGS. 7 to 10, the three piezoelectric elements 5 are not arranged. It may be equally divided. By eliminating the electrode 7 serving as the common electrode and individually switching the voltage applied between the electrodes 8 of the respective piezoelectric elements 5, bending vibration in the opposite direction is applied to the piezoelectric elements 5 disposed on both sides of the optical fiber 2. This can cause the optical fiber 2 to vibrate in an arbitrary pattern.

The number of the piezoelectric elements 5 is not limited, and the electrodes 7, 8 divided into three or more regions along the circumferential direction around the longitudinal axis of the elastic body 4 are divided into one or two piezoelectric elements 5. The arrangement may be adopted. By reducing the number of the piezoelectric elements 5 so as to be smaller than the number of divided regions of the electrode 7.8, it is possible to reduce the influence on the vibration due to the manufacturing error of each piezoelectric element 5 and the variation of the sticking position.

Further, in the present embodiment, the piezoelectric element 5 is disposed on the surface on the base end side of the elastic body 4, but instead, the piezoelectric element 5 is disposed on the surface on the distal end side as shown in FIG. You may.
In addition, as shown in FIG. 12, the piezoelectric element 5 may be arranged on both end surfaces in the thickness direction of the elastic body 4, that is, both surfaces on the distal end side and the base end side. In this case, the force generated in each region in the circumferential direction is doubled as compared with the case where the piezoelectric element 5 is arranged only on one side, and the amplitude of the tip 2a of the optical fiber 2 can be easily increased. There is an advantage.

Further, although the piezoelectric element 5 has been exemplified as the electromechanical conversion element, a magnetostrictive element may be used.
Further, the elastic body 4 is exemplified as a disk-shaped body, but may be a polygonal flat body. In this case, not only a perfect circle and a regular polygon, but also an ellipse, an arbitrary polygon (preferably having six or more corners), or a combination of these circles or polygons may be used. Similarly, a case has been described in which the piezoelectric element 5 is circular by arranging a plurality of arc-shaped piezoelectric elements, but a polygonal shape may be formed by arranging a plurality of isosceles triangular elements. As described above, since the elastic body 4 has a disk shape or a polygonal flat plate shape, the shape of the electromechanical conversion element can be formed into an arc-shaped or triangular shape that can be easily molded.

DESCRIPTION OF SYMBOLS 1 Optical fiber scanner 2 Optical fiber 2a Tip 3 Vibration part 4 Elastic body 5 Piezoelectric element (electromechanical conversion element)
Reference Signs List 10 lighting device 50 light source 60 light detection unit 100 observation device

Claims (7)

1. An optical fiber for guiding the illumination light and emitting the illumination light from the tip,
   A vibrating unit for vibrating the tip of the optical fiber in a direction intersecting the longitudinal axis of the optical fiber,
   The vibrating portion is provided on at least one of a flat elastic body that holds the optical fiber in a state where the optical fiber penetrates in the thickness direction, and at least one of end faces in the thickness direction of the elastic body, and at least three crossing the longitudinal axis. An optical fiber scanner comprising: an electromechanical transducer capable of expanding and contracting in a direction.
2. The optical fiber scanner according to claim 1, wherein the electromechanical transducer has electrodes polarized in three or more divided regions along a circumferential direction around the longitudinal axis of the elastic body.
3. 3. The optical fiber scanner according to claim 2, wherein the arrangement of the electrodes is equal.
4. The optical fiber scanner according to claim 1, wherein the electromechanical transducer is disposed on both end faces in the thickness direction of the elastic body.
5. The optical fiber scanner according to any one of claims 1 to 4, wherein the elastic body has a disk shape or a polygonal flat plate shape.
6. A light source for generating illumination light,
   The optical fiber scanner according to any one of claims 1 to 5, wherein a base end of the optical fiber is connected to the light source.
   A lighting device comprising: a voltage supply unit configured to supply a voltage to the electromechanical conversion element.
7. A lighting device according to claim 6,
   A light detection unit that detects return light returning from the subject when the subject is irradiated with the illumination light from the lighting device.

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