JP2013081680A - Optical scanning endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanning endoscope system that automatically corrects a scanning position.SOLUTION: This optical scanning endoscope system includes: an optical fiber that guides light incident on an incident end to an emitting end and emits it from the emitting end; an optical fiber scanning means provided near the emitting end of the optical fiber and close to the incident end of the optical fiber, bends the optical fiber by pressing the side face of the optical fiber from first and second directions orthogonal to the longitudinal direction of the optical fiber and orthogonal to each other, and spirally rotates and scans the emitting end of the optical fiber; a control means that controls a bending quantity and a bending direction of the optical fiber; and a detecting means that is disposed on the emitting end side of the optical fiber with respect to the optical fiber scanning means and detects the rotation trajectory of the emitting end of the optical fiber. The control means controls the bending quantity and the bending direction of the optical fiber, on the basis of the rotation trajectory of the emitting end of the optical fiber detected by the detecting means, such that the rotation trajectory of the emitting end of the optical fiber forms a substantially circular shape.

Description

  The present invention relates to an optical scanning endoscope system that scans light guided by an optical fiber with respect to an observation site and receives reflected light to form an image.

  2. Description of the Related Art Conventionally, a confocal endoscope apparatus is known as one of optical scanning endoscope systems in which light guided by an optical fiber is scanned with respect to an observation site and the reflected light is received and imaged. (For example, Patent Document 1). The confocal endoscope apparatus irradiates a living tissue in a body cavity with laser light, and extracts only the reflected light on the object-side focal plane of the objective optical system from the reflected light from the irradiated living tissue. Thus, the living tissue can be observed at a higher magnification than an observation image obtained by a normal endoscope optical system. In a confocal endoscope apparatus, a laser beam applied to a living tissue is scanned two-dimensionally or three-dimensionally so that it cannot be observed at a magnification of an observation image obtained by a normal endoscope optical system. It is configured so that an object can be observed and a tomographic part of a living tissue can be observed.

  In recent years, an optical scanning endoscope system has been proposed in which light guided by an optical fiber is scanned in a spiral manner with respect to an observation site, and the reflected light is received and imaged (for example, a patent). Literature 2-4). In such an optical scanning endoscope system, a single mode type optical fiber is provided inside the endoscope, and a base end portion thereof is held in a cantilever shape by a piezoelectric actuator. Then, the piezoelectric actuator modulates and amplifies the vibration amplitude, two-dimensionally vibrates (resonates) the fiber tip according to the natural frequency, and drives the tip of the optical fiber in a spiral shape. As a result, the illumination light guided from the light source by the optical fiber is irradiated spirally toward the observation site, and an image of the irradiation region (scanning region) is acquired.

  In recent years, an optical scanning endoscope system configured to scan light in a spiral shape as described in Patent Documents 2 to 4, a confocal endoscope as described in Patent Document 1 is used. Application to an apparatus has also been proposed (for example, Patent Document 5).

JP 2000-121961 A US Pat. No. 6,856,712 US Pat. No. 6,959,130 US Pat. No. 6,975,898 JP 2010-162090 A

  The optical scanning endoscope systems described in Patent Documents 2 to 5 include a plurality of piezoelectric actuators at the base end portion of the optical fiber in order to scan the optical fiber two-dimensionally, and each piezoelectric actuator has a predetermined amount. The tip of the optical fiber is scanned in a spiral shape by bending the optical fiber in a predetermined direction by applying a voltage having a period and amplitude. However, since the characteristics of each piezoelectric actuator are usually different (that is, there are variations), even if a voltage having a predetermined period and amplitude is applied to each piezoelectric actuator, an accurate circular scan is not obtained, and a distorted circle is not obtained. Scanning is a shape (for example, an ellipse). For this reason, conventionally, it has been necessary to perform some kind of calibration, such as adjusting the voltage applied to the piezoelectric actuator while monitoring the light irradiated in a spiral shape.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to detect the scanning position of the fiber and to automatically correct the scanning position so as to obtain an accurate spiral scan. An optical scanning endoscope system is provided.

  In order to achieve the above object, an optical scanning endoscope system according to the present invention guides light incident on an incident end to an output end and emits the light from the output end, and in the vicinity of the output end of the optical fiber. The optical fiber is bent by pressing the side face of the optical fiber from the first and second directions orthogonal to the longitudinal direction of the optical fiber and orthogonal to each other. An optical fiber scanning means for rotating and scanning the emission end of the optical fiber in a spiral shape, a control means for controlling the bending amount and the bending direction of the optical fiber, and an optical fiber arranged on the emission end side of the optical fiber relative to the optical fiber scanning means. Detecting means for detecting the rotation trajectory of the output end of the fiber, and the control means rotates the output end of the optical fiber detected by the detection means so that the rotation trajectory of the output end of the optical fiber is substantially circular. And controlling the bending amount and bending direction of the optical fiber on the basis of the trajectory.

  With such a configuration, since the scanning position is automatically corrected so that the rotation trajectory of the output end of the optical fiber becomes a substantially circular shape, the user can perform the optical scanning type endoscope without performing troublesome calibration as in the prior art. A mirror system can be used.

  The detecting means is provided in the vicinity of the output end of the optical fiber, and is arranged at regular intervals on an annular magnet through which the optical fiber penetrates and on a circumference separated by a fixed distance from the rotation center axis of the optical fiber. It can be set as the structure provided with two or more magnetic sensors. In this case, the number of magnetic sensors is four, and it is preferable that two magnetic sensors are arranged along the first and second directions. According to such a configuration, it is possible to accurately detect the rotation locus of the emission end of the optical fiber.

  The direction of the magnetic flux detected by the magnetic sensor arranged along the first direction may be different from the direction of the magnetic flux detected by the magnetic sensor arranged along the second direction by 180 °. According to such a configuration, it is possible to easily and accurately detect the rotation locus of the exit end of the optical fiber.

  Further, the optical fiber scanning means includes two piezoelectric actuators arranged along the first and second directions, and the control means controls the amplitude and phase of the voltage applied to each piezoelectric actuator to control the light. A configuration in which the bending amount and the bending direction of the fiber can be controlled. According to such a configuration, by controlling the amplitude and phase of the voltage applied to each piezoelectric actuator, it is possible to easily correct the rotation locus of the emission end of the optical fiber so as to be substantially circular.

  In addition, an optical fiber moving means for moving the output end of the optical fiber in the longitudinal direction of the optical fiber is provided, the detecting means detects the moving amount of the optical fiber in the longitudinal direction, and the control means is a movement detected by the detecting means. The optical fiber moving means may be controlled while monitoring the amount to move the emission end of the optical fiber in the longitudinal direction of the optical fiber. According to such a configuration, it is not necessary to provide a separate sensor or the like in order to detect the amount of movement of the optical fiber in the longitudinal direction, so that the entire apparatus can be configured compactly.

  In addition, an optical system that collects light emitted from the exit end of the optical fiber, a confocal pinhole disposed at a position conjugate with a condensing point of the light collected by the optical system, and the output of the optical fiber Image signal detecting means for receiving reflected light of light emitted from the end through a confocal pinhole and detecting an image signal; and image generating means for generating a confocal image using the detected image signal; It can also be set as the structure provided with.

  According to the present invention, an optical scanning endoscope system capable of detecting a scanning position of a fiber and automatically correcting the scanning position so as to obtain an accurate spiral scan is provided.

1 is a block diagram illustrating a configuration of an optical scanning endoscope system according to an embodiment of the present invention. It is a figure which shows schematically the structure of the confocal optical unit which the optical scanning endoscope system of embodiment of this invention has. It is a figure which shows schematically the structure of the biaxial actuator which the optical scanning endoscope system of embodiment of this invention has. It is a figure which shows the rotation locus | trajectory of the front-end | tip of an optical fiber on an XY approximate surface. It is a figure which shows the relationship between the displacement amount of the front-end | tip of an optical fiber on a XY approximate surface in a X (or Y) direction, and a sampling period and a braking period. It is a figure which shows roughly the structure of the fiber position detection sensor which the optical scanning endoscope system of embodiment of this invention has. It is a figure which shows typically the relationship between a magnetic sensor and a magnet. It is a figure which shows the output voltage of a magnetic sensor when the front-end | tip of an optical fiber rotates so that a spiral pattern may be drawn. It is a figure which shows the positional relationship of a magnet and a fiber position detection sensor when the front-end | tip of an optical fiber advances / retreats to a Z direction. It is a figure which shows the output voltage of a magnetic sensor when the front-end | tip of an optical fiber moves to a Z direction, rotating so that a spiral pattern may be drawn. It is a flowchart of the trajectory correction process performed in the optical scanning endoscope system of the embodiment of the present invention.

  Hereinafter, an optical scanning endoscope system according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an optical scanning endoscope system 1 according to an embodiment of the present invention. The optical scanning endoscope system 1 of the present embodiment is a system designed by applying the principle of a confocal microscope, and is preferably configured to observe a subject with high magnification and high resolution. As shown in FIG. 1, the optical scanning endoscope system 1 includes a system main body 100, a confocal probe 200, and a monitor 300. Confocal observation using the optical scanning endoscope system 1 is performed in a state where the distal end surface of the flexible tubular confocal probe 200 is applied to the subject.

  The system main body 100 includes a light source 102, an optical demultiplexer / multiplexer (photocoupler) 104, a damper 106, a CPU 108, a CPU memory 110, an optical fiber 112, a light receiver 114, a video signal processing circuit 116, an image memory 118, and a video signal output. A circuit 120 is included. The confocal probe 200 includes an optical fiber 202, a confocal optical unit 220, a sub CPU 206, a sub memory 208, and a scanning driver 210.

  The light source 102 emits excitation light that excites the drug administered into the body cavity of the patient in accordance with the drive control of the CPU 108. The excitation light enters the optical demultiplexer / multiplexer 104. An optical connector 152 is coupled to one of the ports of the optical demultiplexer / multiplexer 104. The unnecessary port of the optical demultiplexer-multiplexer 104 is coupled to a damper 106 that terminates the excitation light emitted from the light source 102 without reflection. The excitation light incident on the former port passes through the optical connector 152 and enters the optical system arranged in the confocal probe 200.

  The proximal end of the optical fiber 202 is optically coupled to the optical demultiplexer / multiplexer 104 through the optical connector 152. The tip of the optical fiber 202 is housed in a confocal optical unit 220 incorporated in the tip of the confocal probe 200. The excitation light emitted from the optical demultiplexer / multiplexer 104 passes through the optical connector 152 and enters the proximal end of the optical fiber 202, then transmits through the optical fiber 202 and is emitted from the distal end of the optical fiber 202.

  FIG. 2 is a diagram schematically showing the configuration of the confocal optical unit 220. Hereinafter, for convenience of describing the confocal optical unit 220, the longitudinal direction of the confocal optical unit 220 is defined as the Z direction, and two directions orthogonal to the Z direction and orthogonal to each other are defined as the X direction and the Y direction. As shown in FIG. 2, the confocal optical unit 220 has a metal outer cylinder 221 that accommodates various components. The outer cylinder 221 holds a cylindrical mount 222 having an outer wall surface shape corresponding to the inner wall surface shape of the outer cylinder 221 so as to be slidable coaxially (Z direction). The distal end of the optical fiber 202 (hereinafter referred to as “202a”) is inserted through openings formed in the base end surfaces of the outer cylinder 221 and the mount 222, and is fixed and supported by the mount 222. The tip 202 a of the optical fiber 202 functions as a secondary point light source of the optical scanning endoscope system 1, and the position of the tip 202 a that is a point light source periodically changes based on control by the CPU 108.

  The sub memory 208 (FIG. 1) stores probe information such as identification information and various properties of the confocal probe 200. The sub CPU 206 reads probe information from the sub memory 208 when the system is activated, and transmits the probe information to the CPU 108 via the electrical connector 154 that electrically connects the system main body 100 and the confocal probe 200. The CPU 108 stores the transmitted probe information in the CPU memory 110. The CPU 108 reads the stored probe information when necessary, generates a signal necessary for controlling the confocal probe 200, and transmits the signal to the sub CPU 206. The sub CPU 206 designates a setting value necessary for the scan driver 210 in accordance with the control signal transmitted from the CPU 108.

  The scanning driver 210 generates a drive signal according to the designated set value, and drives and controls the cylindrical biaxial actuator 223 that is bonded and fixed to the outer peripheral surface of the optical fiber 202 near the tip 202a. FIG. 3 is a diagram schematically showing the configuration of the biaxial actuator 223. As shown in FIG. 3, the biaxial actuator 223 includes a pair of X-axis electrodes (“223X” and “223X ′” in the figure) and Y-axis electrodes (“223Y” in the figure) connected to the scanning driver 210. , “223Y ′”) on a piezoelectric body, and each electrode constitutes four independent actuators.

  The scan driver 210 applies an AC voltage X to the X-axis electrode 223X of the 2-axis actuator 223, and generates an AC voltage X ′ having the same frequency and the same amplitude as the AC voltage X and having a phase different by 180 ° as X The piezoelectric body is resonated in the X direction by being applied to the shaft electrode 223X ′. The scan driver 210 applies an AC voltage Y having the same frequency and substantially the same amplitude as the AC voltage X and having a phase difference of 90 ° to the Y-axis electrode 223Y, and has the same frequency as the AC voltage Y and substantially the same. An AC voltage Y ′ having the same amplitude and a phase difference of 180 ° is applied to the Y-axis electrode 223Y ′ to resonate the piezoelectric body in the Y direction. The AC voltages X, X ′, Y, and Y ′ each have an amplitude that increases linearly in proportion to time, and are effective values over time (X), (X ′), (Y), and (Y ′). X), (X ′), (Y), defined as the voltage reaching (Y ′). As described above, as a result of the piezoelectric body resonating in the X direction and the Y direction, the tip 202a of the optical fiber 202 is combined with the kinetic energy in the X direction and the Y direction by the biaxial actuator 223, and is combined with the XY plane. On the surface to be approximated (hereinafter referred to as “XY approximate surface”), it rotates so as to draw a spiral pattern around the central axis AX. The rotation trajectory of the tip 202a increases in proportion to the applied voltage, and has the largest diameter when an AC voltage having an effective value (X), (X ′), (Y), or (Y ′) is applied. Draw a trajectory. FIG. 4 shows the rotation locus of the tip 202a on the XY approximate plane.

  The excitation light is continuous light and is emitted from the tip 202a of the optical fiber 202 during a period from the start of application of the AC voltages X, X ′, Y, Y ′ to the biaxial actuator 223 until the stop of application. Hereinafter, for convenience of explanation, this period is referred to as a “sampling period”. When the application of the AC voltages X, X ′, Y, and Y ′ to the biaxial actuator 223 is stopped after the sampling period has elapsed, the vibration of the optical fiber 202 is attenuated. The circular motion of the tip 202a on the XY approximate plane converges as the vibration of the optical fiber 202 is attenuated, and stops on the central axis AX after a predetermined time. Hereinafter, for convenience of explanation, a period from the end of the sampling period until the tip 202a stops on the central axis AX (more precisely, in order to guarantee the stop on the central axis AX, calculation required to stop) The period of time slightly longer than the above time) is referred to as a “braking period”. The period corresponding to one frame is composed of one sampling period and one braking period. In order to shorten the braking period, a reverse phase voltage may be applied to the biaxial actuator 223 in the initial stage of the braking period to positively apply a braking torque. FIG. 5 shows the relationship between the amount of displacement (amplitude) of the tip 202a in the X (or Y) direction on the XY approximate plane, the sampling period, and the braking period.

  An objective optical system 224 (FIG. 2) is installed in front of the tip 202a of the optical fiber 202. The objective optical system 224 is composed of a plurality of optical lenses, and is held by the outer cylinder 221 via a lens frame (not shown). The lens frame is fixed and supported relative to the mount 222 inside the outer cylinder 221. Therefore, the optical lens group held by the lens frame slides in the Z direction inside the outer cylinder 221 together with the mount 222.

  A motor 226 having a rotating shaft 226 a extending in the Z direction is attached to the base end surface of the outer cylinder 221. A screw is cut on the surface of the rotating shaft 226 a, and the tip of the rotating shaft is inserted into a screw hole provided in the mount 222. A compression coil spring 225 is attached between the base end surface of the mount 222 and the inner wall surface of the outer cylinder 221. The compression coil spring 225 is initially compressed and sandwiched in the Z direction from the natural length, and preloads the motor 226. The scan driver 210 generates a drive signal corresponding to the set value designated by the sub CPU 206 and controls the motor 266. The motor 226 moves the mount 222 forward and backward in the Z direction together with the optical fiber 202 according to the input drive signal.

  The excitation light emitted from the tip 202a of the optical fiber 202 passes through the objective optical system 224 and forms a spot on the surface or surface layer of the subject. The spot formation position is displaced in the Z-axis direction in accordance with the advance / retreat of the tip 202a that is a point light source. That is, the confocal optical unit 220 three-dimensionally scans the subject by combining the periodic circular motion of the tip 202a on the XY approximate plane by the biaxial actuator 223 and the advance and retreat in the Z direction.

  Since the tip 202a of the optical fiber 202 is disposed at the front focal position of the objective optical system 224, it functions as a confocal pinhole. Therefore, only the fluorescence from the condensing point optically conjugate with the tip 202a is incident on the tip 202a among the scattering components (fluorescence) of the subject excited by the excitation light. The fluorescence propagates through the optical fiber 202, passes through the optical connector 152, and enters the optical demultiplexer / multiplexer 104. The optical demultiplexer / multiplexer 104 separates the incident fluorescence from the excitation light emitted from the light source 102 and guides it to the optical fiber 112. The fluorescence propagates through the optical fiber 112 and is detected by the light receiver 114. For the light receiver 114, in order to detect weak light with low noise, for example, a highly sensitive photodetector such as a photomultiplier tube is used.

  The detection signal detected by the light receiver 114 is input to the video signal processing circuit 116. The video signal processing circuit 116 operates under the control of the CPU 108 to obtain a digital detection signal by sample-holding and AD converting the detection signal at a constant rate. Here, when the position (trajectory) of the tip 202a of the optical fiber 202 during the sampling period is determined, the spot forming position in the observation region (scanning region) corresponding to the position and the return light from the spot forming position are detected. Thus, the signal acquisition timing for obtaining the digital detection signal is almost uniquely determined. As will be described later, in the present embodiment, the rotation locus of the tip 202a of the optical fiber 202 is detected in advance, and if the rotation locus is distorted, correction is automatically performed. Accordingly, since the position (trajectory) of the tip 202a of the optical fiber 202 during the sampling period can be stably obtained, the digital detection signal is obtained at a predetermined timing obtained from the position of the tip 202a of the optical fiber 202. The CPU memory 110 stores a remap table that associates the signal acquisition timing of the determined digital detection signal with the pixel position (pixel address).

  The video signal processing circuit 116 refers to the remapping table and assigns the point image represented by each digital detection signal to the pixel address according to the signal acquisition timing. Hereinafter, for convenience of explanation, the above assignment work is referred to as remapping. The video signal processing circuit 116 buffers an image signal constituted by a spatial arrangement of each point image in the image memory 118 according to the remapping result in a frame unit. The buffered signal is read from the image memory 118 by the video signal processing circuit 116 at a predetermined timing and is swept out to the video signal output circuit 120. The video signal output circuit 120 converts the video signal into a video signal conforming to a predetermined standard such as NTSC (National Television System Committee) or PAL (Phase Alternating Line) and outputs the video signal to the monitor 300. On the display screen of the monitor 300, a three-dimensional confocal image of a subject with high magnification and high resolution is displayed.

  As described above, in this embodiment, AC voltages X, X ′, Y, and Y ′ are applied to the X-axis electrodes 223X and 223X ′ and the Y-axis electrodes 223Y and 223Y ′ that constitute the biaxial actuator 223, respectively. Then, the tip 202a of the optical fiber 202 is rotated so as to draw a spiral pattern by resonating (that is, bending) the biaxial actuator 223 in the X direction and the Y direction. Here, the displacement amount (amplitude) of the biaxial actuator 223 in the X direction and the Y direction basically depends on the voltage applied to each electrode. Variations in the characteristics of the actuators occur due to variations in temperature settings, variations in applied voltage during polarization, and the like. For this reason, even if the same voltage is applied to each electrode, it is not always displaced by the same amount. If the characteristics of each actuator are different, the tip 202a of the optical fiber 202 is an ideal circular spiral pattern. Don't be. Therefore, in the present embodiment, as will be described later, the rotation locus of the tip 202a of the optical fiber 202 is detected in advance, and if the rotation locus is distorted, it is automatically corrected.

  FIG. 6 is a diagram schematically showing the configuration of the fiber position detection sensor 227, and the base end side of the outer cylinder 221 (that is, the left side to the right side in FIG. 2) is viewed from the distal end side of the outer cylinder 221 in FIG. It is a front view at the time. However, for convenience of explanation, the objective optical system 224 is omitted in FIG.

  As shown in FIGS. 2 and 6, an annular magnet 228 is attached near the tip 202 a of the optical fiber 202 and closer to the tip 202 a of the optical fiber 202 than the biaxial actuator 223. An annular fiber position detection sensor 227 is attached along the inner wall surface of the outer cylinder 221 so as to surround the magnet 228. The fiber position detection sensor 227 includes four magnetic sensors 227a, 227b, 227c, and 227d on the surface (inner surface) facing the magnet 228. The magnetic sensor 227a faces the X-axis electrode 223X, the magnetic sensor 227b faces the X-axis electrode 223X ′, the magnetic sensor 227c faces the Y-axis electrode 223Y, and the magnetic sensor 227d is the Y-axis electrode 223Y ′. Are arranged on the circumference centered on the central axis AX of the optical fiber 202 at a predetermined interval. The magnetic sensors 227a, 227b, 227c, and 227d are configured by, for example, Hall elements, and the magnetic directions detected by the magnetic sensors 227a and 227c arranged along the X direction and the magnetism arranged along the Y direction. It is arranged so that the direction of the magnetic field detected by the sensors 227b and 227d is opposite (that is, the direction of the magnetic sensor is reversed by 180 °). The magnetic field detected by each magnetic sensor is converted into a voltage and sent to the CPU 108 via the scanning driver 210, the sub CPU 206 and the electrical connector 154.

  As described above, when the tip 202a of the optical fiber 202 rotates so as to draw a spiral pattern, the magnet 228 disposed in the vicinity of the tip 202a of the optical fiber 202 and the magnetic sensors 227a, 227b, 227c, 227d are relative to each other. The positional relationship changes. FIG. 7 is a diagram schematically illustrating the relationship between the magnetic sensor 227a (227b, 227c, or 227d) and the magnet 228. FIG. 7A is a diagram showing the relationship between the magnet 228 and the magnetic sensor 227a when the tip 202a of the optical fiber 202 is stopped on the central axis AX. FIG. 7B is a diagram showing the relationship between the magnet 228 and the magnetic sensor 227a when the tip 202a of the optical fiber 202 is rotating in a spiral shape. As shown in FIG. 7A, in the present embodiment, when the tip 202a of the optical fiber 202 is stopped on the central axis AX, the distance between the magnet 228 and the magnetic sensor 227a is sufficiently large, The magnetic flux (magnetic field) of the magnet 228 is configured not to be detected by the magnetic sensor 227a. On the other hand, as shown in FIG. 7B, when the tip 202a of the optical fiber 202 rotates, the magnet 228 approaches the magnetic sensor 227a, so that a magnetic flux corresponding to the distance between the magnet 228 and the magnetic sensor 227a is generated. It is configured to be detected by the magnetic sensor 227a.

  FIG. 8 is a diagram illustrating output voltages of the magnetic sensors 227a, 227b, 227c, and 227d when the tip 202a of the optical fiber 202 rotates so as to draw a spiral pattern. FIG. 8A is a diagram illustrating output voltages of the magnetic sensors 227a, 227b, 227c, and 227d when the tip 202a of the optical fiber 202 rotates in a spiral shape with a normal circular orbit. FIG. 8B is a diagram showing output voltages of the magnetic sensors 227a, 227b, 227c, and 227d when the tip 202a of the optical fiber 202 rotates in a spiral shape on an elliptical orbit extending in the X direction. FIG. 8C shows the output voltage of the magnetic sensors 227a, 227b, 227c, and 227d when the tip 202a of the optical fiber 202 rotates in an elliptical orbit extending obliquely with respect to the X and Y directions. FIG. In FIGS. 8A to 8C, only the state when the tip 202a of the optical fiber 202 rotates once is shown for convenience of explanation.

  As shown in FIG. 8A, when the distal end 202a of the optical fiber 202 rotates once in a normal circular orbit about the central axis AX, the magnet 228 is a space surrounded by the magnetic sensors 227a, 227c, 227b, and 227d. 1 turn. At this time, the circumference on which the magnetic sensors 227a, 227c, 227b, and 227d are arranged and the circular orbit around which the tip 202a of the optical fiber 202 rotates are concentric circles about the central axis AX, and the magnet 228 is the magnetic sensor 227a. 227c, 227b, and 227d are approached at a constant speed and separated from each other. Accordingly, the output voltage from the magnetic sensors 227a, 227c, 227b, and 227d is a waveform obtained by combining four chevron waveforms when the horizontal axis is time, and the amplitude of each chevron waveform (that is, the output of each magnetic sensor). The amplitude of the voltage) and the period (the time from the peak to the peak of the output voltage of each magnetic sensor) are substantially constant. When the CPU 108 receives such a voltage, the CPU 108 determines that the tip 202a of the optical fiber 202 is rotating in a normal circular orbit.

  As shown in FIG. 8B, when the tip 202a of the optical fiber 202 makes one revolution in an elliptical orbit extending in the X direction, the magnet 228 makes one revolution in the space surrounded by the magnetic sensors 227a, 227c, 227b, and 227d. To do. However, since the amplitude in the Y direction is smaller than the amplitude in the X direction, the distance between the magnet 228 and the magnetic sensors 227a and 227b when the magnet 228 is closest to the magnetic sensors 227a and 227b, and the magnet 228 The distance between the magnet 228 and the magnetic sensors 227c and 227d when closest to the magnetic sensors 227c and 227d is different. Accordingly, the output voltage from the magnetic sensors 227a, 227c, 227b, and 227d is a combination of four mountain-shaped waveforms with a constant period when the horizontal axis is time, as in FIG. The amplitude of the output voltage of the magnetic sensors 227c and 227d is smaller than the amplitude of the output voltage of the magnetic sensors 227a and 227b. When the CPU 108 receives such a voltage, the CPU 108 determines that the tip 202a of the optical fiber 202 is not rotating in a normal circular orbit during a trajectory correction process described later, and normalizes the elliptical orbit extending in the X direction. To correct circular orbit.

  As shown in FIG. 8C, when the tip 202a of the optical fiber 202 makes one rotation along an elliptical orbit extending obliquely with respect to the X direction and the Y direction, the magnet 228 is moved to the magnetic sensors 227a, 227c, 227b, and 227d. The space surrounded by is rotated once. However, since the major and minor axes of the elliptical orbit are tilted with respect to the X and Y axes, the distance between the magnet 228 and each magnetic sensor when the magnet 228 is closest to each magnetic sensor 227a, 227c, 227b, 227d. The distance is longer than that in the case of FIG. 8A (when rotating in a normal circular orbit). Further, the time until the magnet 228 approaches the magnetic sensors 227a, 227c, 227b, and 227d is different. Therefore, the output voltages from the magnetic sensors 227a, 227c, 227b, and 227d are similar to FIGS. 8 (a) and 8 (b). The amplitudes of the waveforms of the magnetic sensors 227c and 227d are smaller than those in FIGS. 8A and 8B, and the period of the mountain-shaped waveform is not constant. When the CPU 108 receives such a voltage, the CPU 108 determines that the distal end 202a of the optical fiber 202 is not rotating in a normal circular orbit in a trajectory correction process to be described later, and is inclined with respect to the X direction and the Y direction. The elliptical orbit extending in the direction is corrected to a normal circular orbit.

  As described above, in the optical scanning endoscope system 1 of the present embodiment, when the rotational trajectory of the tip 202a of the optical fiber 202 is detected and it is determined that it is not a normal circular trajectory, a trajectory correction process described later is performed. Is corrected to a normal circular orbit. Then, after the tip 202a of the optical fiber 202 is adjusted so as to have a normal circular orbit, it is further moved back and forth in the Z direction by a minute distance (for example, 0.5 mm), and the subject is scanned three-dimensionally.

  FIG. 9 is a schematic diagram for explaining the positional relationship between the magnet 228 and the fiber position detection sensor 227 when the distal end 202a of the optical fiber 202 moves back and forth in the Z direction. FIG. 9A is a diagram showing a positional relationship between the magnet 228 and the fiber position detection sensor 227 when the tip 202a of the optical fiber 202 is retracted most in the Z direction (moved to the negative side in the Z direction). FIG. 9C is a diagram showing a positional relationship between the magnet 228 and the fiber position detection sensor 227 when the tip 202a of the optical fiber 202 protrudes most in the Z direction (moves to the plus side in the Z direction). FIG. 9B shows the positional relationship between the magnet 228 and the fiber position detection sensor 227 when the tip 202a of the optical fiber 202 is positioned in the middle of the position of FIG. 9A and the position of FIG. 9C. FIG. In the confocal optical unit 220 of the present embodiment, the tip 202a of the optical fiber 202 acquires one frame image within one sampling period while rotating so as to draw a spiral pattern. The tip 202a of the optical fiber 202 moves at a predetermined pitch from the position shown in FIG. 9 (a) to the position shown in FIG. 9 (c) every time the braking period is reached, thereby obtaining a plurality of images in the Z direction. It has gained. FIG. 10 is a diagram illustrating an output voltage of the magnetic sensor 227a (227b, 227c, or 227d) when the tip 202a of the optical fiber 202 moves in the Z direction while rotating so as to draw a spiral pattern. In FIG. 10, the sawtooth wave-like thin solid line indicates the output voltage of the magnetic sensor 227a at each time (at each position in the Z direction), and the thick solid line indicates the peak of the output voltage of the magnetic sensor 227a that changes in a sawtooth wave shape. It is a connected curve. Further, “a” in FIG. 10 corresponds to the case where the optical fiber 202 is positioned at the position in FIG. 9A (hereinafter referred to as “retracted position”), and “b” in FIG. 9B. This corresponds to when the optical fiber 202 is positioned at a position (hereinafter referred to as “intermediate position”), and “c” indicates that the optical fiber 202 is positioned at a position (hereinafter referred to as “projection position”) in FIG. Corresponds when positioned.

  As shown in FIGS. 9A and 10, in a state where the optical fiber 202 is in the retracted position, the magnet 228 is disposed offset from the magnetic sensor 227a toward the minus side in the Z direction. In this state, when the tip 202a of the optical fiber 202 rotates to draw a spiral pattern, the magnetic sensor 227a (227b, 227c, or 227d) receives a predetermined magnetic flux from the magnet 228 (a magnetic flux whose output voltage is Vth). Receive. When the tip 202a of the optical fiber 202 is moved to the plus side in the Z direction from this state, the magnet 228 approaches the magnetic sensor 227a, and the magnetic flux detected by the magnetic sensor 227a increases, so the output voltage of the magnetic sensor 227a gradually increases. . When the magnet 228 moves to a position facing the magnetic sensor 227a (that is, an intermediate position), the peak of the output voltage of the magnetic sensor 227a becomes substantially constant (FIG. 9B, “b” in FIG. 10). Next, when the tip 202a of the optical fiber 202 further moves to the plus side in the Z direction from this state, the magnet 228 is separated from the magnetic sensor 227a, and the magnetic flux detected by the magnetic sensor 227a is reduced, so that the output voltage of the magnetic sensor 227a gradually increases. Becomes smaller. And if the front-end | tip 202a of the optical fiber 202 moves to a protrusion position, the magnet 228 is offset and arrange | positioned rather than the magnetic sensor 227a to the Z direction plus side. In this state, when the tip 202a of the optical fiber 202 rotates so as to draw a spiral pattern, the magnetic sensor 227a receives a predetermined magnetic flux (a magnetic flux whose output voltage is Vth) from the magnet 228 (FIG. 9C). ), “C” in FIG.

  Thus, when the tip 202a of the optical fiber 202 moves in the Z direction, the outputs of the magnetic sensors 227a, 227b, 227c, and 227d change. In the present embodiment, the amount of movement of the tip 202a of the optical fiber 202 in the Z direction is monitored using such changes in the outputs of the magnetic sensors 227a, 227b, 227c, and 227d. Therefore, even when there is a backlash between the mount 222 and the rotating shaft 226a of the motor 226, the position of the tip 202a of the optical fiber 202 is accurately controlled in the Z direction.

  Next, the trajectory correction process executed by the CPU 108 of this embodiment will be described. FIG. 11 is a flowchart of the trajectory correction process executed by the CPU 108 of this embodiment. The trajectory correction process according to the present embodiment is a kind of calibration subroutine performed prior to the image acquisition / display operation of the optical scanning endoscope system 1. When the optical scanning endoscope system 1 is activated, the CPU 108 This is performed by reading a program stored in a memory (not shown) into the CPU memory 110 and executing it. As shown in FIG. 11, when the trajectory correction process is started, the CPU 108 executes Step S1.

  In step S1, the CPU 108 resets the correction number parameter i to “0”. Here, the correction number parameter i is a variable for counting the number of executions of a correction process (step S9) described later. Next, the process proceeds to step S2.

  In step S2, the CPU 108 drives the motor 226 via the sub CPU 206 and the scanning driver 210 to move the tip 202a of the optical fiber 202 to an intermediate position (position shown in FIG. 9B). Next, the process proceeds to step S3.

  In step S <b> 3, the CPU 108 detects the trajectory of the tip 202 a of the optical fiber 202. Specifically, the CPU 108 transmits a reference set value to the scanning driver 210 via the sub CPU 206 to exchange AC with the X-axis electrodes 223X and 223X ′ and the Y-axis electrodes 223Y and 223Y ′ of the biaxial actuator 223. Voltages X, X ′, Y, and Y ′ are applied, respectively. Here, the reference set value is a parameter of the scanning driver 210 for rotating the tip 202a of the optical fiber 202 so as to draw a reference spiral pattern, and thereby the X-axis electrodes 223X, 223X ′ and Reference AC voltages X, X ′, Y, and Y ′ are applied to the Y-axis electrodes 223Y and 223Y ′. The CPU 108 receives the output voltages from the magnetic sensors 227a, 227b, 227c, and 227d, and detects the trajectory of the tip 202a of the optical fiber 202. Next, the process proceeds to step S4.

  In step S4, the CPU 108 monitors the output voltages from the magnetic sensors 227a, 227b, 227c, and 227d, and determines whether or not the motor is rotating in a normal circular orbit. When the waveform shown in FIG. 8A is detected and it is determined that the rotation is in a normal circular orbit (step S3: YES), the process proceeds to step S5, and the optical fiber 202 is moved to the retracted position (that is, The trajectory correction process is terminated after moving to the initial position in the Z direction. On the other hand, in step S4, when a waveform as shown in FIG. 8B or FIG. 8C is detected and it is determined that the motor does not rotate in a normal circular orbit (step S4: NO), the process proceeds to step S6. Proceed to

  In step S6, the CPU 108 increments the correction number parameter i, and the process proceeds to step S7.

  In step S7, the CPU 108 determines whether or not the correction number parameter i has reached a predetermined upper limit value. In the correction process (step S9) described later, the amplitudes of the AC voltages X, X ′, Y, and Y ′ applied to the X-axis electrodes 223X and 223X ′ and the Y-axis electrodes 223Y and 223Y ′ of the biaxial actuator 223 The phase is adjusted and the trajectory of the tip 202a of the optical fiber 202 is corrected to be a circular trajectory, but can be applied to the X-axis electrodes 223X and 223X ′ and the Y-axis electrodes 223Y and 223Y ′ of the biaxial actuator 223. Since the voltage has a predetermined allowable range, the malfunction (failure) of the biaxial actuator 223 is determined by determining whether or not the correction number parameter i has reached a predetermined upper limit value. In step S7, when it is determined that the correction count parameter i has reached the predetermined upper limit value (step S7: YES), the CPU 108 determines that there is a problem with the biaxial actuator 223 and displays an error display on the monitor 300. (Step S8), the trajectory correction process is terminated. On the other hand, when it is determined in step S7 that the correction number parameter i has not reached the predetermined upper limit (step S7: NO), the process proceeds to step S9.

  In step S9, the CPU 108 executes correction processing so that the trajectory of the tip 202a of the optical fiber 202 is a circular trajectory. Specifically, the output voltages from the magnetic sensors 227a, 227b, 227c, and 227d are monitored, and the X-axis electrodes 223X and 223X ′ of the biaxial actuator 223 and the Y-axis are used so that a reference spiral pattern is obtained. The amplitudes and phases of the AC voltages X, X ′, Y, and Y ′ applied to the electrodes 223Y and 223Y ′ are respectively adjusted by a predetermined amount. For example, as shown in FIG. 8B, when the tip 202a of the optical fiber 202 is rotating in an elliptical orbit extending in the X direction, the CPU 108 applies AC to the Y-axis electrodes 223Y and 223Y ′. The set value of the scan driver 210 is changed so that the amplitudes of the voltages Y and Y ′ increase by a predetermined amount. Further, for example, as shown in FIG. 8C, when the tip 202a of the optical fiber 202 rotates in an elliptical orbit extending obliquely with respect to the X direction and the Y direction, the CPU 108 Setting values of the scan driver 210 so that the amplitudes and phases of the AC voltages X, X ′, Y, Y ′ applied to the electrodes 223X, 223X ′ and Y-axis electrodes 223Y, 223Y ′ increase or decrease by a predetermined amount, respectively. To change. As described above, the amplitude and phase of the AC voltages X, X ′, Y, and Y ′ are adjusted by a predetermined amount. Then, the process returns to step S3, and the processes from step S3 to S9 are repeated, so that the trajectory of the tip 202a of the optical fiber 202 is corrected until the reference spiral pattern is obtained.

  Thus, by executing the trajectory correction subroutine, the trajectory of the tip 202a of the optical fiber 202 is automatically calibrated so as to have a reference spiral pattern. In this state, in the optical scanning endoscope system 1 of the present embodiment, the tip 202a of the optical fiber 202 is moved in the Z direction while rotating in a spiral pattern, and the subject is scanned three-dimensionally. A 3D image is acquired.

  The above is the description of the embodiment of the present invention. However, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the technical idea. For example, in the present embodiment, the configuration using the two-axis actuator 223 provided with the X-axis electrodes 223X and 223X ′ and the Y-axis electrodes 223Y and 223Y ′ has been described. It is good also as a structure using. In this case, since the number of electrodes increases according to the number of axes, it is desirable to increase the number of magnetic sensors according to the number of electrodes.

  In the present embodiment, the four magnetic sensors 227a, 227b, 227c, and 227d are centered on the central axis AX so as to face the X-axis electrodes 223X and 223X ′ and the Y-axis electrodes 223Y and 223Y ′. Although described as a configuration arranged on the circumference, since it is only necessary to determine whether or not the trajectory of the tip 202a of the optical fiber 202 is a circular trajectory, at least three or more magnetic sensors are centered on the central axis AX. What is necessary is just to arrange | position on the circumference.

  In step S3 of the trajectory correction process of the present embodiment, the reference set value is transmitted to the scanning driver 210, and the X-axis electrodes 223X and 223X ′ and the Y-axis electrodes 223Y and 223Y ′ of the biaxial actuator 223 are transmitted. The reference AC voltages X, X ′, Y, and Y ′ are applied to the power source, but the setting value adjusted by the trajectory correction process is stored in the memory. In step S3, the adjustment is performed by the previous trajectory correction process. The set value may be read from the memory. With such a configuration, the time required for the trajectory correction process is shortened.

  In addition, the trajectory correction processing of the present embodiment has been described as a kind of calibration subroutine performed prior to the image acquisition / display operation of the optical scanning endoscope system 1, but it is also performed during normal image acquisition / display operation. The output voltages of the magnetic sensors 227a, 227b, 227c, and 227d are monitored, and are always fed back to the AC voltages X, X ′, Y, and Y ′ so that the trajectory of the tip 202a of the optical fiber 202 has a reference spiral pattern. It is good also as a structure.

  Further, in the present embodiment, the optical scanning endoscope system 1 has been described as a configuration including the confocal probe 220 that emits excitation light, but is not limited to this configuration, and Patent Documents 2 to 4 are provided. It is also possible to apply to a normal optical scanning endoscope system that emits white light as described in the above.

1 Optical Scanning Endoscope System 100 System Main Body 102 Light Source 104 Optical Demultiplexer / Multiplexer 106 Damper 108 CPU
110 CPU memory 112 Optical fiber 114 Light receiver 116 Video signal processing circuit 118 Image memory 120 Video signal output circuit 200 Confocal probe 202 Optical fiber 206 Sub CPU
208 Sub-memory 210 Scan driver 220 Confocal optical unit 221 Outer cylinder 222 Mount 223 Two-axis actuator 223X, 223X ′ X-axis electrode 223Y, 223Y ′ Y-axis electrode 224 Objective optical system 225 Compression coil spring 226 Motor 227 Fiber position detection Sensors 227a, 227b, 227c, 227d Magnetic sensor 228 Magnet

Claims (7)

An optical fiber that guides light incident on the incident end to the exit end, and exits from the exit end;
A first and a second are provided near the emission end of the optical fiber and near the incident end of the optical fiber, and the side surfaces of the optical fiber are orthogonal to the longitudinal direction of the optical fiber and orthogonal to each other. An optical fiber scanning unit that bends the optical fiber by pressing from a direction and rotationally scans the exit end of the optical fiber in a spiral shape;
Control means for controlling the bending amount and bending direction of the optical fiber;
A detecting means that is disposed closer to the output end of the optical fiber than the optical fiber scanning means, and detects a rotation locus of the output end of the optical fiber;
With
The control means includes a bending amount and a bending direction of the optical fiber based on the rotation locus of the emission end of the optical fiber detected by the detection means so that the rotation locus of the emission end of the optical fiber is substantially circular. An optical scanning endoscope system characterized by controlling the above.   The detection means is provided in the vicinity of the output end of the optical fiber, and is arranged at equal intervals on a circular magnet through which the optical fiber penetrates and on a circumference separated by a fixed distance from the rotation center axis of the optical fiber. The optical scanning endoscope system according to claim 1, further comprising at least three or more magnetic sensors.   The optical scanning endoscope system according to claim 2, wherein the number of the magnetic sensors is four, and two magnetic sensors are arranged along the first and second directions.   The direction of the magnetic flux detected by the magnetic sensor arranged along the first direction is different from the direction of the magnetic flux detected by the magnetic sensor arranged along the second direction by 180 °. The optical scanning endoscope system according to claim 3. The optical fiber scanning means includes two piezoelectric actuators arranged along the first and second directions,
The said control means controls the bending amount and bending direction of the said optical fiber by controlling the amplitude and phase of the voltage applied to each said piezoelectric actuator, The any one of Claims 1-4 characterized by the above-mentioned. The optical scanning endoscope system according to Item. An optical fiber moving means for moving the exit end of the optical fiber in the longitudinal direction of the optical fiber;
The detection means detects the amount of movement of the optical fiber in the longitudinal direction,
The control means controls the optical fiber moving means while monitoring the amount of movement detected by the detecting means to move the output end of the optical fiber in the longitudinal direction of the optical fiber. The optical scanning endoscope system according to any one of claims 1 to 5. An optical system for condensing light emitted from the exit end of the optical fiber;
A confocal pinhole disposed at a position conjugate with the condensing point of the light collected by the optical system;
Image signal detection means for receiving reflected light of light emitted from the emission end of the optical fiber via the confocal pinhole and detecting an image signal;
Image generating means for generating a confocal image using the detected image signal;
The optical scanning endoscope system according to any one of claims 1 to 6, further comprising:

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