JP6401382B2 - Optical fiber scanner and scanning observation apparatus - Google Patents

Description

  The present invention relates to an optical fiber scanner and a scanning observation apparatus.

  A scanning endoscope that oscillates the tip of an optical fiber by vibration generated by applying an alternating voltage to a piezoelectric element and scans illumination light emitted from the tip of the optical fiber in a spiral shape on a subject. It is known (for example, refer to Patent Document 1). In the scanning endoscope of Patent Document 1, the drive voltage for driving the optical fiber is linearly changed, and the spiral scanning trajectory of the illumination light has a constant interval at all positions.

Japanese Patent No. 5225038

  If it is desired to acquire a higher resolution image, the inconvenience of only increasing the number of turns of the tip of the optical fiber per unit time or increasing the time required to acquire one image. There is. That is, in the former case, for example, when the piezoelectric element is vibrated near a specific frequency like the resonance frequency, it is difficult to easily change the number of turns per unit time. In the latter case, the moving image becomes awkward due to a decrease in the frame rate, or the fast movement of the subject cannot be observed.

  The present invention has been made in view of the above-described circumstances, and is clear even when enlarged without changing the number of turns per unit time at the tip of the optical fiber and without reducing the frame rate. An object of the present invention is to provide an optical fiber scanner and a scanning observation apparatus that can acquire an image.

  One aspect of the present invention is an optical fiber that guides illumination light and emits it from the tip, and a piezoelectric that is vibrated by applying an alternating voltage and that oscillates the tip of the optical fiber at a constant frequency. An optical fiber scanner comprising an element and a control unit that changes a rate of change of the amplitude in each period in which the amplitude of the alternating voltage monotonously increases or decreases monotonously.

  According to this aspect, the illumination is guided by the optical fiber and emitted from the distal end by disposing the subject in front of the optical fiber and applying an alternating voltage to the piezoelectric element to oscillate the distal end of the optical fiber. Light is scanned across the subject. Then, the tip of the optical fiber can be displaced spirally by monotonously increasing or monotonically decreasing the amplitude of the alternating voltage applied to the piezoelectric element.

  That is, when the amplitude of the alternating voltage is monotonously increased, the scanning trajectory of the illumination light by the optical fiber is formed in a spiral shape from the center to the periphery. When the amplitude of the alternating voltage is monotonously decreased, the illumination light by the optical fiber is The scanning trajectory is formed in a spiral shape from the periphery toward the center.

At this time, by changing the rate of change of the amplitude of the alternating voltage, the scanning trajectory of the illumination light can be made dense, and in the area where the scanning trajectory is dense, the illumination light is densely applied to the subject. Can be irradiated.
That is, by changing the rate of change of the amplitude of the alternating voltage, the scanning trajectory of the illumination light in a specific region is made dense, and a high-resolution image can be acquired for that region. In this case, it is possible to irradiate illumination light at a high density in a necessary region without changing the vibration period of the piezoelectric element or increasing the frame rate.

In the above aspect, the control unit may change the amplitude of the alternating voltage at a smaller change rate at both ends than the center of each period.
By doing so, it is possible to irradiate the subject with illumination light at high density at both ends of each period in which the amplitude of the alternating voltage monotonously increases or decreases monotonously. The smaller the rate of change of the amplitude of the alternating voltage, the denser the scanning locus.

  For example, when applied to an endoscope inserted into a lumen such as a blood vessel, it is necessary to acquire a high-resolution image so that the front surface in the traveling direction and the surrounding lumen wall surface can be enlarged and observed. is there. It is possible to irradiate a necessary region with high-density illumination light by making the center and the peripheral part of the spiral scanning locus dense.

Moreover, in the said aspect, the said control part may change the amplitude of the said alternating voltage to a sine wave form.
By doing in this way, the density of a scanning locus can be changed smoothly. As a result, excessive acceleration is prevented from being applied to the optical fiber, and the load on the optical fiber can be reduced.

According to another aspect of the present invention, a scanning includes any one of the above optical fiber scanners and a light detection unit that detects return light returning from the subject when the illumination light is scanned on the subject by the optical fiber scanner. This is a mold observation device.
According to this aspect, it is possible to acquire an image that partially includes a high-resolution region without changing the period of alternating voltage applied to the piezoelectric element and the frame rate. By matching the higher resolution area with the necessary area and matching the lower resolution area with the unnecessary area, the necessary area can be observed with a clear image even if it is enlarged.

  According to another aspect of the present invention, the optical fiber scanner includes the optical fiber scanner, and a light detection unit that detects return light returning from the subject when the illumination light is scanned on the subject by the optical fiber scanner. A center opening for transmitting illumination light emitted from the tip of the optical fiber when the amplitude of the alternating voltage is smaller than a predetermined threshold, The scanning observation apparatus includes a conical mirror that deflects illumination light emitted from the tip of the optical fiber radially outward when the amplitude of is is greater than or equal to the threshold value.

According to this aspect, of the illumination light scanned in a spiral shape, the illumination light in the vicinity of the center of the spiral scanning locus passes through the central opening of the conical mirror and is irradiated to the front subject. On the other hand, the illumination light in the vicinity of the periphery of the spiral scanning trajectory is changed radially outward by the conical mirror and irradiated to the surrounding subject.
In the case of a scanning observation apparatus that is inserted into a lumen such as a blood vessel, the illumination light is scanned with a high-density scanning locus on the subject in front and the inner wall of the surrounding lumen. A visual image can be acquired.

  According to the present invention, there is an effect that a clear image can be obtained even when enlarged without changing the number of turns per unit time at the tip of the optical fiber and without reducing the frame rate. .

It is a longitudinal section showing a scanning type observation device concerning one embodiment of the present invention. It is a perspective view which shows the optical fiber scanner which concerns on one Embodiment of this invention with which the scanning observation apparatus of FIG. 1 is equipped. It is a figure which shows an example of the waveform of the alternating voltage applied to the optical fiber scanner of FIG. It is a figure which shows the locus | trajectory of the front-end | tip of an optical fiber when the alternating voltage of FIG. 3 is applied. It is a figure which shows the scanning locus | trajectory of the illumination light scanned ahead of the optical fiber scanner when the alternating voltage of FIG. 3 is applied. It is a figure which shows the scanning locus | trajectory of the illumination light scanned to the side of an optical fiber scanner when the alternating voltage of FIG. 3 is applied. It is a longitudinal cross-sectional view which shows the modification of the conical mirror with which the scanning observation apparatus of FIG. 1 is equipped. It is a longitudinal cross-sectional view which shows the modification of the scanning observation apparatus of FIG. It is a longitudinal cross-sectional view which shows the other modification of the scanning observation apparatus of FIG. It is a figure which shows the other example of the waveform of the alternating voltage applied to the optical fiber scanner of FIG. It is a figure which shows the other example of the waveform of the alternating voltage applied to the optical fiber scanner of FIG. It is a figure which shows the other example of the waveform of the alternating voltage applied to the optical fiber scanner of FIG.

An optical fiber scanner 4 and a scanning observation apparatus 1 according to an embodiment of the present invention will be described below with reference to the drawings.
The scanning observation apparatus 1 according to the present embodiment is, for example, an endoscope. As shown in FIG. 1, illumination from a light source (light source unit) 3 is applied to the distal end of an insertion unit 2 inserted into a body cavity. An optical fiber scanner 4 according to the present embodiment that scans light two-dimensionally, a cylindrical outer cylinder member 5 that accommodates the optical fiber scanner 4, and an optical fiber scanner that is disposed at the tip of the outer cylinder member 5 A plurality of illumination lenses 6 that irradiate the subject with illumination light emitted from 4, and a detection optical fiber that is arranged in the circumferential direction on the outer surface of the outer cylinder member 5 and has an incident end near the tip of the outer cylinder member 5 And a conical mirror 8 disposed further forward than the illumination lens 6. In the figure, reference numeral 5 a denotes a cover made of an optically transparent material provided at the tip of the outer cylinder member 5.

  As shown in FIG. 2, the optical fiber scanner 4 guides the illumination light from the light source 3 and emits it from the tip, and the optical fiber at a position spaced from the tip of the optical fiber 9 by a predetermined distance. A cylindrical vibration transmission member 10 that supports the sheet 9 in a penetrating manner, four piezoelectric elements 11 bonded to the outer surface of the vibration transmission member 10 at equal intervals in the circumferential direction, and the piezoelectric element 11 And a control unit 12 for adjusting the alternating voltage.

  The vibration transmission member 10 is made of a conductive metal material, and as shown in FIG. 2, as shown in FIG. 2, a through hole 14 that can penetrate the optical fiber 9 along the longitudinal axis of a regular rectangular column having a circular flange portion 13 at one end. Is formed, and is fixed to the outer cylinder member 5 by the flange portion 13.

  The piezoelectric element 11 is formed in a flat plate shape with electrodes 15 a and 15 b provided on both end faces in the thickness direction, and one electrode 15 a is in electrical contact with each side surface of the regular quadrangular prism portion of the vibration transmitting member 10. It is fixed with. Two pairs of piezoelectric elements 11 arranged at positions facing each other with the optical fiber 9 interposed therebetween are arranged so that their polarization directions are directed in the same direction.

  A lead wire 16 for supplying an alternating voltage for driving the piezoelectric element 11 is connected to the other electrode 15 b of each piezoelectric element 11. Lead wires 16 that supply alternating voltages having the same phase are connected to the piezoelectric elements 11 that are disposed at positions facing each other with the optical fiber 9 interposed therebetween. Reference numeral 17 denotes a GND line connected to the control unit 12 and the flange unit 13.

  As shown in FIG. 3, the control unit 12 applies the two phases of the piezoelectric elements 11 with a phase difference of 90 ° while changing the amplitude of the alternating voltage oscillating at a constant frequency in a sine wave shape. It has become. That is, by applying an alternating voltage to each pair of piezoelectric elements 11, the optical fiber 9 is bent by bending vibration of each pair of piezoelectric elements 11, thereby displacing the tip of the optical fiber 9 in a spiral shape, The illumination light emitted from the tip of the optical fiber 9 is scanned in a spiral shape.

  In this case, in the present embodiment, as shown in FIG. 3, the control unit 12 changes the amplitude of the alternating voltage oscillating at a constant frequency in a sine wave shape, thereby forming a spiral trajectory formed. As shown in FIG. 4, the spirals are formed so as to be dense at the central part and the peripheral part and rough at the intermediate position. FIG. 4 shows, as an example, a scanning locus in the monotonically increasing period P1 of FIG.

  The detection optical fiber 7 guides return light from the subject incident from the incident end to a photodetector (not shown) such as a photomultiplier tube. The photodetector detects the intensity of the return light collected by all the detection optical fibers 7 at each scanning position of the illumination light. The intensity of the detected return light is stored in association with the scanning position.

  As shown in FIG. 1, the conical mirror 8 has a central opening 18 and a reflecting surface 19 made of a conical surface disposed over the entire circumference at an angle of approximately 45 ° with respect to the central axis. ing. And since the conical mirror 8 is arrange | positioned at intervals ahead of the lens 6 for illumination, among the illumination lights inject | emitted ahead via the lens 6 for illumination, the vicinity of the center of a spiral locus is provided. The illumination light LA is irradiated forward through the central opening 18 of the conical mirror 8, and the illumination light LB near the periphery of the spiral locus is deflected by the reflecting surface 19 of the conical mirror 8 and is radially outside. It is designed to irradiate towards the direction.

The operation of the optical fiber scanner 4 and the scanning observation apparatus 1 according to the present embodiment configured as described above will be described below.
In order to observe the inside of a patient's body cavity using the scanning observation apparatus 1 according to the present embodiment, the insertion unit 2 is inserted into the body cavity, the light source 3 is activated, and the alternating voltage is controlled by the control unit 12. Thus, the piezoelectric element 11 is driven.

  Illumination light generated in the light source 3 is guided by the optical fiber 9 and emitted from the tip toward the subject. By the operation of the piezoelectric element 11, the tip of the optical fiber 9 is displaced in a spiral shape, and the illumination light is scanned two-dimensionally on the subject.

  The illumination light LA at the central portion of the spiral locus passes through the central opening 18 provided at the center of the conical mirror 8 and is irradiated forward along the longitudinal direction of the insertion portion 2. When a subject is present in front, as shown in FIG. 5, illumination light is scanned on the subject according to a spiral trajectory.

  On the other hand, the illumination light LB in the peripheral portion of the spiral locus is deflected by the reflecting surface 19 of the conical mirror 8 and irradiated radially outward. As shown in FIG. 6, the illumination light LB deflected radially outward is scanned on the inner wall surface of the body cavity according to a spiral coil-shaped locus.

  When illumination light is irradiated on the subject, return light such as reflected light or fluorescence is generated, received at the incident end of the detection optical fiber 7, and detected by a photodetector. The detected intensity of the return light is stored in association with the scanning position of the illumination light by the optical fiber scanner 4. Thereby, a two-dimensional image of the subject can be acquired.

  In this case, according to the optical fiber scanner 4 according to the present embodiment, the amplitude is changed in a sine wave shape while keeping the frequency of the alternating voltage applied to the piezoelectric element 11 constant, so that it is shown in FIG. Furthermore, the spiral scanning trajectory of the illumination light LA that illuminates the front through the central opening 18 of the conical mirror 8 is formed densely toward the center, and the illumination light can be irradiated with high density.

  According to the scanning observation apparatus 1 according to the present embodiment, the return light from each scanning position that is illuminated with high density is detected, so that a high-resolution front image (direct-view image) can be acquired. . The direct-view image is useful for first finding a lesion site in the body cavity when the scanning observation apparatus 1 is inserted into the body cavity. By acquiring a high-resolution direct-view image, a suspicion of a lesion can be obtained. There is an advantage that a clear image can be observed in detail even if the portion to be seen is enlarged.

  Similarly, as shown in FIG. 6, the spiral coil scanning trajectory of the illumination light LB that is deflected by the reflecting surface 19 of the conical mirror 8 is formed more densely toward the front. The illumination light can be irradiated with high density. Thereby, the side image (side view image) of high resolution can be acquired, so that it goes ahead. The side-view image is an image obtained by photographing the inner wall of the body cavity from the front, and there is an advantage that a lesion portion existing on the inner wall of the body cavity can be enlarged and observed in detail with a clear image.

That is, according to this embodiment, a high-resolution image can be acquired in a necessary region without changing the frequency of the alternating voltage applied to the piezoelectric element 11 and without reducing the frame rate. . Therefore, it is possible to acquire an image that smoothly changes at a high frame rate while efficiently vibrating the piezoelectric element 11 at a frequency near the resonance frequency.
Further, since the amplitude of the alternating voltage is changed in a sine wave shape, the acceleration applied to the optical fiber 9 can be smoothly changed between the monotonously decreasing period P2 and the monotonically increasing period P1.

  In the present embodiment, the conical mirror 8 causes the illumination light in the case where the alternating voltage has an amplitude smaller than a predetermined threshold to pass through the central opening 18 and is used for obtaining a direct-view image, and has an amplitude greater than the threshold. In the case of having the light, the illumination light is deflected by the reflecting surface and used for obtaining the side-view image. Instead, as shown in FIG. 7, a shielding portion 20 made of a material that absorbs illumination light may be provided on a part of the reflection surface 19 of the conical mirror 8 adjacent to the central opening 18. . Thereby, the illumination light of the area | region where the density of a spiral scanning locus | trajectory is low can be absorbed by the shielding part 20, and only the illumination light of the area | region where the density of a scanning locus | trajectory is high can be used for image acquisition.

  Further, in the present embodiment, the direct-view image illumination light LA and the side-view image illumination light LB are branched by the conical mirror 8, but instead, as shown in FIG. The illumination light L of all scanning trajectories may be used for direct-view images without disposing the conical mirror 8. Further, as shown in FIG. 9, a mirror 21 that deflects the illumination light L of all scanning trajectories by approximately 90 ° may be disposed and used for side-view images.

  In this embodiment, since the amplitude of the alternating voltage is changed to a sine wave, it is possible to acquire images one by one in the monotonically increasing period P1 and the monotonically decreasing period P2. The present invention is not limited to this, and as shown in FIG. 10, images are acquired only during the monotonically increasing period P1, or as shown in FIG. 11, only during the monotonically decreasing period P2, and the other periods are: It may decrease or increase earlier.

  In addition, the amplitude of the alternating voltage is changed in a sine wave form. Instead, as shown in FIG. 12, the amplitude of the alternating voltage is varied in the monotonically increasing period P1 and / or the monotonically decreasing period P2. The amplitude of the alternating voltage may be changed by changing the rate of change in a mode other than a sine wave, such as changing linearly at the rate of change. This also makes it possible to make the scanning trajectory of the illumination light in the region where the change rate is small dense.

DESCRIPTION OF SYMBOLS 1 Scanning observation apparatus 4 Optical fiber scanner 7 Optical fiber for detection (light detection part)
8 Conical mirror 9 Optical fiber 11 Piezoelectric element 12 Control unit 18 Center opening

Claims (4)

An optical fiber that guides the illumination light and emits it from the tip;
A piezoelectric element that is vibrated by applying an alternating voltage, and that oscillates the tip of the optical fiber at a constant frequency; and
An optical fiber scanner comprising: a control unit that changes a change rate of the amplitude with a smaller change rate at both ends than the center of each period in each period in which the amplitude of the alternating voltage monotonously increases or monotonously decreases.   The optical fiber scanner according to claim 1, wherein the control unit changes the amplitude of the alternating voltage in a sine wave shape. An optical fiber scanner according to any one of claims 1 to 3,
A scanning observation apparatus comprising: a light detection unit that detects return light that returns from a subject when illumination light is scanned on the subject by the optical fiber scanner. An optical fiber scanner according to claim 1 or claim 3,
A light detection unit that detects return light returning from the subject by scanning the illumination light on the subject by the optical fiber scanner;
A central opening that is disposed in front of the tip of the optical fiber and that transmits illumination light emitted from the tip of the optical fiber when the amplitude of the alternating voltage is smaller than a predetermined threshold; A scanning observation apparatus comprising a conical mirror that deflects illumination light emitted from the tip of the optical fiber radially outward when the amplitude of the alternating voltage is equal to or greater than the threshold value.

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