JP2014149354A - Calibration method and scanning type endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a pixel omission from occurring due to the spreading of an interval of a spiral scanning locus of a scanning light wider than a target value.SOLUTION: A calibration method of a scanning type endoscope system includes: a step of performing a spiral optical scanning by driving an actuator by control means based on a scanning parameter; a step of detecting the spiral optical scanning locus by scanning locus detection means; and an adjustment step of adjusting a scanning parameter by control means so that a spiral optical scanning locus detected by the scanning locus detection means approximately matches a target locus. The adjustment step includes a locus interval adjustment step for adjusting an interval of the spiral optical scanning locus approximately to be constant by changing a drive amount of the actuator.

Description

  The present invention relates to an automatic calibration method for correcting a scanning trajectory of scanning light emitted from an optical scanning endoscope and a scanning endoscope system for performing the automatic calibration method.

  A scanning endoscope system is known in which light guided by an optical fiber is scanned in a spiral manner with respect to an observation site, and reflected light from the observation site is received and imaged (Patent Document 1). In such a 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 biaxial actuator. The biaxial actuator two-dimensionally vibrates (resonates) the tip of the fiber in accordance with the natural frequency while modulating and amplifying the vibration amplitude, 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 scans the observation region in a spiral shape, and an image of the irradiation region (scanning region) is acquired based on the return light from the observation region. The

  In such a scanning endoscope system, reflected light or fluorescence from a scanning region (observation site) is received at a predetermined cycle timing (hereinafter referred to as “sampling points”), and luminance information at each sampling point is received. Is assigned to the display coordinate system of the monitor (the pixel position of the endoscopic image) to display a two-dimensional endoscopic image. Therefore, in order to generate a highly reproducible endoscope image without distortion, it is necessary to accurately match the scanning position of each sampling point with the display coordinate system of the monitor. Therefore, this type of scanning endoscope system is calibrated so as to obtain an ideal scanning pattern while monitoring an actual scanning pattern (scanning trajectory).

JP 2010-515947 A

  In a conventional scanning endoscope system calibration method as described in Patent Document 1, the overall size (specifically, the outermost diameter) and shape of a scanning pattern are adjusted. The interval between the spiral scanning trajectories is not adjusted. Therefore, the interval of the scanning trajectory becomes wider than the assumed range, and as a result, pixel omission may occur in the endoscopic image captured using the scanning endoscope system. FIG. 15 is a diagram schematically showing an example of missing pixels extending in the circumferential direction that occur in an endoscopic image captured using a scanning endoscope system.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent occurrence of pixel omission in imaging of an endoscopic image using a scanning endoscope system.

  According to one embodiment of the present invention, an optical fiber that guides light emitted from a light source, and an X-axis direction that is two radial directions orthogonal to each other while cantilevering and supporting the tip of the optical fiber And driving the actuator in the X-axis direction and the Y-axis direction based on predetermined scanning parameters so that the light emitted from the tip of the optical fiber is scanned in a spiral trajectory. A scanning type including an optical scanning device having a control means for controlling and a scanning locus detecting means for detecting a scanning locus of the scanning light emitted from the tip of the optical fiber and periodically performing a spiral optical scanning. A method for calibrating an endoscope system, in which a control unit drives an actuator based on a scanning parameter to perform a spiral optical scan, and a scanning locus detection unit A step of detecting a trajectory of the optical scan, and an adjustment step in which the control means adjusts the scan parameter so that the spiral optical scan trajectory detected by the scan trajectory detection means substantially coincides with the target trajectory; And the adjustment step includes a trajectory interval adjustment step that adjusts the interval of the spiral optical scanning trajectory to be substantially constant by changing the drive amount of the actuator, and provides a calibration method for a scanning endoscope system. The

  According to this configuration, since the interval between the spiral scanning trajectories is wider than the target value, pixel omission that occurs in an image captured using the scanning light of the optical scanning device for illumination is prevented.

  In the calibration method described above, the trajectory interval adjusting step may include a step of determining a target trajectory interval from the detected spiral scanning optical trajectory.

  In the optical fiber type optical scanning device, there are individual differences in the preferred values of the size and interval of the optical scanning trajectory. Further, the interval between the trajectories of optical scanning also depends on the size (diameter of the outermost circumference) and the shape of the trajectory. Therefore, the target trajectory interval can be set more appropriately by determining it based on the optical scanning trajectory acquired with the size and shape of the trajectory being suitably adjusted.

In the above calibration method, the step of determining the interval between the target trajectories includes the step of calculating the average amplitude r _N of the outermost trajectory from the detected spiral optical scanning trajectory, A value r _N / N obtained by dividing the average amplitude r _N by the number of turns _N of the spiral target locus may be determined as a target locus interval ΔR.

Further, in the above calibration method, the trajectory interval adjusting step includes the step of calculating the adjacent track spacing [Delta] r _n is the n th division and spacing of the (n + 1) revolution trajectory from the trajectory of the detected spiral optical scanning, A first drive amount adjustment step of adjusting the drive amount V _{n + 1} of the actuator when the optical scan of the (n + 1) th round is performed so that the adjacent locus interval substantially coincides with the target locus interval.

Further, the step in the above calibration method, the step of calculating the adjacent track spacing, for calculating the average amplitude r _n and r _{n + 1} of the n peripheral and the n + 1 round trajectory from the trajectory of the detected spiral optical scanning When the steps of the difference _{r n} + 1 -r _n of the average amplitude _{r n + 1} of the average amplitude _{r n} and the n + 1 round trajectory of the n peripheral locus and the adjacent track spacing [Delta] r _n, may have a configuration including.

Further, in the first drive amount adjustment step of the calibration method described above, the actuator when the optical scanning of the (n + 1) th round is performed only when the error of the adjacent trajectory interval with respect to the target trajectory interval exceeds the first tolerance The driving amount V _{n + 1} may be adjusted.

In the above calibration method, the first drive amount adjustment step includes a step of obtaining a target locus amplitude R _{n + 1} that is an amplitude of the (n + 1) th turn of the target locus, and a _first step of the detected spiral optical scanning locus. a step of obtaining a detection trajectory amplitude r _{n + 1} that is an amplitude of n + 1 rounds, a step of adjusting the driving amount V _{n + 1} of the actuator when the optical scanning of the (n + 1) th round is performed to V _{n + 1} ′ by the following calculation formula: It is good also as a structure containing.

  Further, in the above calibration method, it is determined whether or not the amplitude error of the detected spiral optical scanning locus with respect to the target locus is within the second tolerance for each predetermined round of the spiral locus. It is good also as a structure including an amplitude error determination step.

  Further, in the above calibration method, only when the amplitude error exceeds the second tolerance in the amplitude error determination step, the detected spiral shape is detected for each turn after the previous round in which the amplitude error determination step was performed. A second drive amount adjustment step for adjusting the drive amount of the actuator when each round of optical scanning is performed may be configured so that the amplitude of the optical scanning locus substantially coincides with the amplitude of the target locus.

  According to this configuration, errors in adjacent trajectory intervals within the first tolerance in each round accumulate, and the optical scanning trajectory spacing is suitable in each round, but within the first tolerance in each round. By accumulating errors between adjacent trajectory intervals, it is possible to prevent pixel omissions from greatly deviating from the target trajectory on the outer peripheral side.

Further, in the above calibration method, the second drive quantity adjusting step includes the steps of obtaining a target locus amplitude R _n is the n th division of the amplitude of the target locus, the locus of the detected spiral optical scanning first obtaining a n detection trajectory amplitude r _n is the amplitude of the peripheral, the following equation, and adjusting the drive amount V _n of the actuator when the n-th division of the optical scanning is performed V _{n ',} It is good also as a structure containing.

  Further, according to one embodiment of the present invention, the optical fiber that guides the light emitted from the light source, and the X direction that is two radial directions orthogonal to each other while cantilevering and supporting the tip of the optical fiber. An actuator that vibrates in the axial direction and the Y-axis direction, and an X-axis direction and a Y-axis direction of the actuator based on predetermined scanning parameters so that light emitted from the tip of the optical fiber is scanned in a spiral trajectory. A scanning device comprising: a control means for controlling driving; and a scanning locus detection means for detecting a scanning locus of the scanning light emitted from the tip of the optical fiber, and comprising an optical scanning device that periodically performs spiral optical scanning. In the endoscope system, the control means drives the actuator based on the scanning parameter to perform the spiral light scanning, and the spiral light detected by the scanning locus detection means. Adjusting means for adjusting a scanning parameter so that the inspection trajectory substantially coincides with the target trajectory, and the adjusting means changes the drive amount of the actuator to adjust the interval between the spiral optical scanning trajectories. There is provided a scanning endoscope system including trajectory interval adjusting means for adjusting the distance substantially constant.

  According to the calibration method and the scanning endoscope system according to the embodiment of the present invention, pixel omission that occurs in an image captured using scanning light for illumination is prevented.

It is a block diagram which shows the structure of the scanning confocal endoscope system of embodiment of this invention. It is a figure which shows schematically the structure of the confocal optical unit which the scanning confocal 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 (amplitude) of the front-end | tip of an optical fiber on an XY approximate surface in the X (or Y) direction, and a sampling period and a braking period. It is a figure explaining the correspondence of a sampling point and a raster coordinate. It is a schematic diagram of the calibration apparatus of embodiment of this invention. It is a flowchart of the calibration program performed with the scanning confocal endoscope system of embodiment of this invention. It is a figure which shows the initial spot formation position on the light-receiving surface of PSD. It is a figure which shows a mode when XY adjustment is performed by the calibration program. It is a figure which shows the relationship between the movement amount when moving the light-receiving surface of PSD to a Z direction, and the output current of PSD. It is a figure which shows the scanning locus | trajectory of excitation light when predetermined alternating voltage X and Y are applied to a biaxial actuator. It is a figure which shows the scanning locus | trajectory of the excitation light adjusted so that it might become an ideal scanning locus | trajectory by calibration. It is a flowchart which shows the procedure of the process which adjusts a scanning parameter. It is a flowchart which shows the procedure of the process which adjusts the space | interval between the rotations of a spiral scanning locus | trajectory. It is a figure which shows an example of the pixel omission generate | occur | produced in the endoscopic image imaged using the scanning confocal endoscope system.

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

  The scanning confocal endoscope system 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. FIG. 1 is a block diagram showing a configuration of a scanning confocal endoscope system 1 according to an embodiment of the present invention. As shown in FIG. 1, the scanning confocal endoscope system 1 includes a system main body 100, a confocal endoscope 200, a monitor 300, and a calibration device 400. The confocal observation using the scanning confocal endoscope system 1 is performed in a state where the distal end surface of the flexible tubular confocal endoscope 200 is applied to the subject.

  The system body 100 includes a light source 102, an optical demultiplexer / multiplexer (optical coupler) 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 endoscope 200 includes an optical fiber 202, a confocal optical unit 204, a sub CPU 206, a sub memory 208, and a scanning driver 210. In the following description, one end where the objective optical system 204D is disposed in the longitudinal direction of the confocal endoscope 200 is referred to as a distal end, and the other end connected to the system main body 100 is referred to as a proximal end.

  The light source 102 emits excitation light that excites the medicine 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 endoscope 200.

  One end (hereinafter referred to as “base end”) of the optical fiber 202 is optically coupled to the optical demultiplexing / multiplexing device 104 through the optical connector 152. The other end (hereinafter referred to as “tip”) of the optical fiber 202 is housed in a confocal optical unit 204 incorporated in the tip of the confocal endoscope 200. The excitation light emitted from the optical demultiplexer-multiplexer 104 passes through the optical connector 152, enters the proximal end of the optical fiber 202, transmits through the optical fiber 202, and is emitted from the distal end of the optical fiber 202.

  FIG. 2A is a diagram schematically showing the configuration of the confocal optical unit 204. Hereinafter, for convenience of describing the confocal optical unit 204, the longitudinal direction of the confocal optical unit 204 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. The confocal optical unit 204 includes an optical fiber type optical scanning device that vibrates the tip of an optical fiber supported in a cantilever shape and scans light emitted from the tip of the optical fiber on a predetermined surface. ing.

  As shown in FIG. 2A, the confocal optical unit 204 has a metal outer cylinder 204A that houses various components. The outer cylinder 204A holds an inner cylinder 204B having an outer wall surface shape corresponding to the inner wall surface shape of the outer cylinder 204A so as to be slidable coaxially (Z direction). The distal end of the optical fiber 202 (hereinafter referred to as “202a”) is housed and supported in the inner cylinder 204B through openings formed in the base end surfaces of the outer cylinder 204A and the inner cylinder 204B, and is located within the scanning confocal. It functions as a secondary point light source of the endoscope system 1. The position of the tip 202a, which is a point light source, periodically changes according to control by the CPU. In FIG. 2A, a central axis AX is an optical axis of an objective optical system 204D described later, and when the optical fiber 202 arranged in the Z direction is not oscillating, the central axis AX is an optical axis. This coincides with the optical axis (center axis) of the fiber 202.

  The sub memory 208 stores probe information such as identification information and various properties of the confocal endoscope 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 endoscope 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 endoscope 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 corresponding to the designated set value, and drives and controls the biaxial actuator 204C that is bonded and fixed to the outer peripheral surface of the optical fiber 202 near the tip 202a. FIG. 2B is a diagram schematically showing the configuration of the biaxial actuator 204C. As shown in FIG. 2B, the biaxial actuator 204C includes a pair of X-axis electrodes (“X” and “X ′” in the figure) and Y-axis electrodes (in the figure) connected to the scanning driver 210. “Y”, “Y ′”) are piezoelectric actuators formed on a piezoelectric body.

  The scanning driver 210 applies an AC voltage X between the X-axis electrodes of the biaxial actuator 204C to vibrate the piezoelectric body in the X direction, and generates an AC voltage Y having the same frequency as that of the AC voltage X and orthogonal in phase. Applied between the Y-axis electrodes, the piezoelectric body is vibrated in the Y direction. The AC voltages X and Y are respectively defined as voltages that increase linearly in proportion to time and reach effective values (X) and (Y) over time (X) and (Y). The tip 202a of the optical fiber 202 is on a surface that approximates the XY plane (hereinafter referred to as "XY approximate surface") by combining the kinetic energy in the X and Y directions by the biaxial actuator 204C. Rotate 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 draws a circular trajectory having the largest diameter when the AC voltage having the effective values (X) and (Y) is applied. In the present embodiment, the amplitude, phase, and frequency of the AC voltages X and Y are adjusted by calibration described later so that the rotation locus of the tip 202a becomes an ideal scanning locus. . FIG. 3 is a diagram illustrating a rotation locus of the tip 202a on the XY approximate plane adjusted by calibration.

  FIG. 4 is a diagram for explaining the relationship between the amount of displacement (amplitude) in the X (or Y) direction of the tip 202a of the optical fiber 202 on the XY approximate plane and each operation timing of the confocal endoscope 200. The excitation light is continuous light (or pulsed light) and is in the period from immediately after the start of application of AC voltage to the biaxial actuator 204C until the application is stopped (hereinafter, this period is referred to as “sampling period” for convenience of explanation). The light is emitted from the tip 202a of the optical fiber 202. As described above, when an AC voltage is applied to the biaxial actuator 204C, the tip 202a of the optical fiber 202 rotates so as to draw a spiral pattern around the central axis AX. For this reason, during the sampling period, the excitation light emitted from the tip 202a of the optical fiber 202 scans a predetermined circular scanning region around the central axis AX in a spiral shape. When the application of the AC voltage to the biaxial actuator 204C 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 approximate XY plane converges as the vibration of the optical fiber 202 is attenuated, and the vibration of the optical fiber 202 becomes substantially zero after a predetermined time (that is, the tip 202a is on the central axis AX). Almost stop). Hereinafter, for convenience of explanation, a period from the end of the sampling period until the tip 202a substantially stops on the central axis AX is referred to as a “braking period”. After the braking period, the next sampling period is started after a predetermined time has elapsed. Hereinafter, for convenience of description, a period from the end of the braking period to the start of the next sampling period is referred to as a “settling period”. The settling period is a standby time for completely stopping the tip 202a of the optical fiber 202 on the central axis AX. By providing the settling time, the tip 202a can be scanned accurately. The period corresponding to one frame (scanning period) is composed of one sampling period, one braking period, and one settling period. By adjusting the settling period, the period of the scanning period is set to the frame rate. It can be adjusted to match F (fps: frames per second). That is, the settling period can be appropriately set from the relationship between the time until the tip 202a of the optical fiber 202 completely stops and the frame rate F. In order to shorten the braking period, a braking torque may be positively applied by applying a reverse phase voltage to the biaxial actuator 204C in the initial stage of the braking period.

  An objective optical system 204D is installed in front of the tip 202a of the optical fiber 202. The objective optical system 204D is composed of a plurality of optical lenses, and is held by the outer cylinder 204A via a lens frame (not shown). The lens frame is fixed and supported relative to the inner cylinder 204B inside the outer cylinder 204A. Therefore, the optical lens group held by the lens frame slides in the Z direction integrally with the inner cylinder 204B inside the outer cylinder 204A. A cover glass (not shown) is held at the forefront of the outer cylinder 204A (that is, in front of the objective optical system 204D).

  A compression coil spring 204E and a shape memory alloy 204F are attached between the base end surface of the inner cylinder 204B and the inner wall surface of the outer cylinder 204A. The compression coil spring 204E is initially compressed and sandwiched in the Z direction from the natural length. The shape memory alloy 204F has a long bar shape in the Z direction, deforms when an external force is applied at room temperature, and has a property of restoring to a predetermined shape by a shape memory effect when heated to a certain temperature or higher. ing. The shape memory alloy 204F is designed such that the restoring force due to the shape memory effect is larger than the restoring force of the compression coil spring 204E. The scan driver 210 generates a drive signal corresponding to the set value designated by the sub CPU 206, and energizes and heats the shape memory alloy 204F to control the expansion / contraction amount. The shape memory alloy 204F advances and retracts the inner tube 204B in the Z direction together with the optical fiber 202 according to the amount of expansion and contraction.

  The excitation light emitted from the tip 202a of the optical fiber 202 passes through the objective optical system 204D and forms a spot on the surface or surface layer of the subject. The spot forming position is displaced in the Z direction in accordance with the advance / retreat of the tip 202a which is a point light source. That is, the confocal optical unit 204 scans the subject three-dimensionally by combining the periodic circular motion of the tip 202a on the XY approximate plane by the biaxial actuator 204C 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 204D, it functions as a confocal pinhole. Of the scattering component (fluorescence) of the subject excited by the excitation light, only the fluorescence from the condensing point optically conjugate with the tip 202a is incident on the tip 202a. The fluorescence is transmitted 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 is transmitted through the optical fiber 112 and detected by the light receiver 114. The light receiver 114 may be a high-sensitivity photodetector such as a photomultiplier tube in order to detect weak light with low noise.

  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 formation position in the observation region (scanning region) corresponding to the position, the return light (fluorescence) from the spot formation position. The signal acquisition timing (that is, the sampling point) for obtaining the digital detection signal by detecting the signal is almost uniquely determined. As will be described later, in the present embodiment, the scanning locus of the tip 202a is measured in advance using the calibration device 400. Then, the amplitude, phase, frequency, etc. of the voltage applied to the biaxial actuator 204C are adjusted so that the measured scanning locus becomes an ideal scanning pattern (that is, an ideal spiral scanning pattern) The position on the image corresponding to the sampling point (the pixel position of the endoscopic image displayed on the monitor 300) is determined. The correspondence between the sampling point and the pixel position (pixel address) of the endoscopic image is stored in the CPU memory 110 as a remap table. For example, when the endoscopic image is composed of 15 pixels in the horizontal direction (X direction) and 15 pixels in the vertical direction (Y direction), the position of the excitation light (sampling point) and the pixels of the endoscopic image that are sequentially sampled The relationship with the position (raster coordinates) is as shown in FIG. 5, and the CPU 108 obtains the pixel position (raster coordinates) of the endoscopic image corresponding to each sampling point based on this relationship and creates a remap table. . FIG. 5 shows sampling points in the central portion and peripheral portion of the scanning region in consideration of the visibility of the drawing, but in actuality, a large number of sampling points are taken along the spiral scanning locus. There is a point.

  The video signal processing circuit 116 refers to the remapping table and assigns each digital detection signal obtained at each sampling point as corresponding pixel address data. 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 swept from the image memory 118 to the video signal output circuit 120 at a predetermined timing, and the video signal conforms to a predetermined standard such as NTSC (National Television System Committee) or PAL (Phase Alternating Line). To be output to the monitor 300. On the display screen of the monitor 300, a high-magnification and high-resolution three-dimensional confocal image of the subject (in this specification, simply referred to as “endoscopic image”) is displayed.

  As described above, since the image of the subject is constructed by the remapping operation, in order to obtain an endoscope image without distortion, it is necessary to rotate the tip 202a so as to have an ideal spiral scanning pattern. is there. However, since the characteristics of each component constituting the scanning confocal endoscope system 1 usually vary within a predetermined range, each product has a characteristic specific to each product (hereinafter referred to as “product specific characteristic”). The simple scanning trajectory as shown in FIG. 3 cannot be obtained simply by assembling. Therefore, in the scanning confocal endoscope system 1 of the present embodiment, calibration described later is performed in order to cancel such product-specific characteristics.

  FIG. 6 is a schematic diagram of a calibration apparatus 400 used during calibration according to the present embodiment. In the calibration, the rotation locus of the tip 202a of the optical fiber 202 is detected, and this rotation locus becomes an ideal rotation locus (that is, the scanning locus of the excitation light emitted from the confocal optical unit 204 is the reference). The amplitude, phase, and frequency of the AC voltages X and Y applied to the biaxial actuator 204C are adjusted to create a new remapping table (so that a scanning trajectory is obtained). Hereinafter, in this specification, parameters adjusted by calibration, mainly the amplitude, phase, and frequency of the AC voltages X and Y, are collectively referred to as “adjustment parameters”. The calibration apparatus 400 will be described as a configuration independent of the system main body 100, but may be a part of the configuration incorporated in the system main body 100.

  As shown in FIG. 6, the calibration apparatus 400 includes a unit support 420, a case 402, an XYZ stage 408, a stage drive motor 410, a calibration circuit 412, and the like.

  The unit support 420 is a substantially cylindrical member fixed to the main body (not shown) of the calibration device 400, and the inner diameter thereof is configured to be slightly larger than the outer diameter of the confocal optical unit 204. . At the time of calibration, the focus optical unit 204 is inserted into the unit support 420 and positioned and fixed in each of the X, Y, and Z directions.

  A PSD 404, a PSD substrate 405, and a relay lens unit 406 are attached to the case 402. The PSD 404 is mounted on the PSD substrate 405 and is disposed on the base end surface side of the case 402 so that the light receiving surface is positioned on the XY plane (in other words, orthogonal to the Z direction). The PSD 404 receives the excitation light emitted from the confocal optical unit 204 and detects its position (that is, the position of the excitation light on the light receiving surface) (details will be described later). The relay lens unit 406 is disposed on the distal end side (confocal optical unit 204 side) of the case 402 so that the optical axis is in the Z direction. The relay lens unit 406 is a so-called magnifying optical system having a plurality of lenses inside, and is arranged so that the optical axis and the rear focal point F2 are positioned at the center of the light receiving surface of the PSD 404. Further, the front focal point F1 of the relay lens unit 406 is adjusted so as to substantially coincide with the focal point of the objective optical system 204D of the confocal optical unit 204 (that is, the condensing position of the excitation light) by calibration described later. That is, the relay lens unit 406 functions to enlarge the projection image (that is, the excitation light scanning region (maximum shake width)) at the condensing position of the excitation light emitted from the confocal optical unit 204. Note that the inside of the case 402 is shielded so that external light does not enter, and the PSD 404 detects the excitation light from the confocal optical unit 204 with a high SN ratio. The detection current of the PSD 404 is output to the calibration circuit 412 via the PSD substrate 405.

  The case 402 is fixed on an XYZ stage 408 that can move in the X, Y, and Z directions by a stage drive motor 410. The stage drive motor 410 is, for example, a stepping motor, and receives a signal from the calibration circuit 412 during calibration described later, and moves the XYZ stage 408 in a predetermined direction. In the present embodiment, the moving resolution of the XYZ stage 408 (that is, the moving amount of the XYZ stage 408 with respect to one step of the stage drive motor 410) is set to about 10 μm.

  The calibration circuit 412 is a circuit capable of bidirectional communication with the CPU 108. The calibration circuit 412 moves the XYZ stage 408 via the stage drive motor 410 under the control of the CPU 108 during calibration. Further, the calibration circuit 412 converts the detected current of the PSD 404 output from the PSD substrate 405 into a voltage and outputs it to the CPU 108 as a detected voltage.

  FIG. 7 is a flowchart of a calibration program executed during calibration. The calibration program is executed by the CPU 108 when the user (surgeon) inserts the focus optical unit 204 into the unit support 420 and inputs a predetermined instruction from a user interface (not shown) of the system main body 100. It is a subroutine. For convenience of explanation, each processing step of calibration is abbreviated as “S” in the explanation and drawings in this specification.

  As shown in FIG. 7, when the calibration program is started, the CPU 108 executes S1. In S <b> 1, the position of the case 402 is adjusted with respect to the focus optical unit 204. In this process, the CPU 108 controls the light source 102 so that the excitation light is continuously emitted, and controls the operation driver 210 so as to stop the voltage application to the biaxial actuator 204C. As a result, the excitation light emitted from the optical fiber 202 travels along the central axis AX, passes through the relay lens unit 406, and forms an image on the light receiving surface of the PSD 404 (FIG. 6). In the present specification, the initial spot formation position of the excitation light when no voltage is applied to the biaxial actuator 204C is hereinafter referred to as “initial spot formation position”.

  FIG. 8 is a diagram showing the initial spot formation position P on the light receiving surface of the PSD 404. As described above, since the scanning confocal endoscope system 1 has product-specific characteristics, the initial spot formation position does not necessarily coincide with the center of the PSD 404 and is detected by being shifted in the X and Y directions. Further, since the focal point of the objective optical system 204D of the confocal optical unit 204 also varies somewhat depending on the parts, the front focal point F1 of the relay lens unit 406 and the focal point of the objective optical system 204D of the confocal optical unit 204 (that is, excitation light). Does not necessarily match. Therefore, in S1, the case 402 is moved in the X and Y directions (XY adjustment) so that the initial spot formation position substantially coincides with the center of the light receiving surface of the PSD 404, and the front focal point F1 of the relay lens unit 406 is set. The case 402 is moved in each direction of Z so that the focal point of the objective optical system 204D of the confocal optical unit 204 is substantially coincident (Z adjustment).

ここで、Ｉ_Ｘ１は、電極Ｘ１から出力される電流であり、Ｉ_Ｘ２は、電極Ｘ２から出力される電流であり、Ｉ_Ｙ１は、電極Ｙ１から出力される電流であり、Ｉ_Ｙ２は、電極Ｙ２から出力される電流である。また、Ｌは、ＰＳＤ４０４の受光面の中心から各電極までの距離である。 (XY adjustment)
The PSD 404 includes a pair of X-direction electrodes X1 and X2 and a pair of Y-direction electrodes Y1 and Y2. The spot formation position on the light receiving surface of the PSD 404 detects a current output from each electrode. Sought by. Specifically, the positions Xp and Yp on the light receiving surface of the PSD 404 at the initial spot formation position P are obtained by the following equations (Equation 3 and Equation 4).

Here, I _X1 is a current output from the electrode X1, I _X2 is a current output from the electrode X2, I _Y1 is a current output from the electrode Y1, and I _Y2 is an electrode This is the current output from Y2. L is a distance from the center of the light receiving surface of the PSD 404 to each electrode.

In S1, the CPU 108 determines the current I _X1 output from the electrode _X1 , the current I _X2 output from the electrode _X2 , the current I _Y1 output from the electrode Y1, and the electrode from the detection voltage of the PSD 404 input from the calibration circuit 412. The currents I _Y2 output from _Y2 are respectively obtained, and the positions Xp and Yp on the light receiving surface of the PSD 404 at the initial spot formation position P are obtained based on the above formulas 3 and 4. Then, the CPU 108 drives the stage drive motor 410 so that Xp and Yp are minimized (that is, the initial spot formation position substantially coincides with the center of the light receiving surface of the PSD 404), and moves the XYZ stage 408 in the X direction. And move in the Y direction. However, as described above, the XYZ stage 408 of this embodiment has a moving resolution, and actually there is a backlash of the stage drive motor 410, and these error factors are magnified by the relay lens unit 406. For this reason, it is difficult to accurately match the spot of the excitation light with the center of the light receiving surface of the PSD 404. Therefore, in the present embodiment, a PSD 404 having a light receiving surface (10 mm × 10 mm) sufficiently larger than the scanning region (diameter 5 mm) of excitation light on the PSD 404 is used.

  FIG. 9 is a diagram illustrating a state when the XY adjustment is performed in S1. For convenience of explanation, FIG. 9 shows a state where the initial spot formation position P has moved to the center O of the light receiving surface of the PSD 404. When the initial spot formation position P moves to the center O of the light receiving surface of the PSD 404, the excitation light scanning region T becomes a region having a diameter of 5 mm centered on the center O of the light receiving surface. The light receiving surface of the PSD 404 is sufficiently larger than the scanning area T of the excitation light, and the shaded area surrounding the scanning area T (area corresponding to a width of about 2.5 mm) is adjusted during adjustment in the XY direction. It is designed to function as a proxy α. In other words, even if backlash or the like of the stage drive motor 410 occurs, the scanning region T is configured to be always within the light receiving surface of the PSD 404.

(Z adjustment)
FIG. 10 shows the relationship between the movement amount z when the light-receiving surface of the PSD 404 is moved in the Z direction, the total current in the X direction (I _X1 + I _X2 ), and the total current in the Y direction (I _Y1 + I _Y2 ). It is a graph which shows. Here, Z = 0 is a position when the front focal point F1 of the relay lens unit 406 coincides with the focal point of the objective optical system 204D of the confocal optical unit 204. As shown in FIG. 9, when the front focal point F1 of the relay lens unit 406 coincides with the focal point of the objective optical system 204D of the confocal optical unit 204, the excitation light is most focused on the light receiving surface of the PSD 404, and the current in the X direction is reduced. The sum (I _X1 + I _X2 ) and the sum of currents in the Y direction (I _Y1 + I _Y2 ) take extreme values. Therefore, in S1, Z adjustment is performed by using the sum of currents in the X direction (I _X1 + I _X2 ) and the sum of currents in the Y direction (I _Y1 + I _Y2 ) as an index representing the beam diameter of the excitation light. Specifically, the CPU 108 determines the current I _X1 output from the electrode _X1 , the current I _X2 output from the electrode _X2 , and the current I _Y1 output from the electrode Y1 from the detection voltage of the PSD 404 output from the calibration circuit 412. The current I _Y2 output from the electrode Y2 is obtained, respectively, and the sum of currents in the X direction (I _X1 + I _X2 ) and the sum of currents in the Y direction (I _Y1 + I _Y2 ) are obtained. Then, the CPU 108 takes the extreme values of the sum of currents in the X direction (I _X1 + I _X2 ) and the sum of currents in the Y direction (I _Y1 + I _Y2 ) (that is, with the front focal point F1 of the relay lens unit 406). The stage drive motor 410 is driven to move the XYZ stage 408 along the Z direction (so that the focal point of the objective optical system 204D of the confocal optical unit 204 substantially matches).

  As described above, in S1, XY adjustment for moving the case 402 in the X and Y directions and Z adjustment for moving the case 402 in the Z direction are performed, and the initial spot formation position is substantially the center of the light receiving surface of the PSD 404. In addition, the front focal point F1 of the relay lens unit 406 and the focal point of the objective optical system 204D of the confocal optical unit 204 are adjusted to substantially coincide. In the above, for convenience of explanation, the description has been made in the order of XY adjustment and Z adjustment, but it is also possible to perform the adjustment in the order of Z adjustment and XY adjustment. If the Z adjustment is performed before the XY adjustment, the XY adjustment can be performed in a state where the excitation light spot is narrowed. Therefore, the aberration of the objective optical system 204D and the relay lens unit 406, the inclination of the objective optical system 204D, The XY adjustment can be performed with high accuracy without being affected by the mounting error of the focus optical unit 204. Next, the process proceeds to S2 (FIG. 7).

  In S <b> 2, the CPU 108 applies uniform (ie, default) AC voltages X and Y to the biaxial actuator 204 </ b> C to rotate the tip 202 a of the optical fiber 202, and spirals the light receiving surface of the PSD 404. A scanning locus of the excitation light to be scanned is detected. FIG. 11 is a diagram showing a scanning trajectory of excitation light when the default AC voltages X and Y are applied to the biaxial actuator 204C. As described above, since the scanning confocal endoscope system 1 has product-specific characteristics, an ideal scanning locus as shown in FIG. 3 is not obtained in a state where the default AC voltages X and Y are applied. For example, the scanning locus is distorted in an elliptical shape. Next, the process proceeds to S3.

  In S3, the CPU 108 evaluates the scanning trajectory of the excitation light detected in S2, and determines whether or not the scanning trajectory is within a specified tolerance (that is, whether or not it is an allowable scanning trajectory). The specified tolerance is determined in advance from the allowable distortion amount of the image, and the CPU 108 determines the size, shape (roundness), scanning speed, etc. of the scanning area from the scanning trajectory of the excitation light detected in S2. To evaluate. In S3, when it is determined that it is within the tolerance (S3: YES), the process proceeds to S5, and when it is determined that it is not within the tolerance (S3: NO), the process proceeds to S4.

  In S4, the CPU 108 changes adjustment parameters (scanning parameters) of the AC voltages X and Y applied to the biaxial actuator 204C. Specifically, the CPU 108 determines the frequencies of the AC voltages X and Y based on the evaluation result of the scanning trajectory of the excitation light in S3 (specifically, the cantilever-supported light). The driving efficiency of the confocal optical unit 204 is increased by adjusting the frequency so as to match the resonance frequency of the tip of the fiber. If there is a problem with the size of the scanning locus, the frequency of the AC voltages X and Y is adjusted to enlarge or reduce the scanning locus. If there is a problem with the shape of the scanning locus, the shape of the scanning locus is changed by adjusting the phases of the AC voltages X and Y. The CPU 108 repeatedly executes the processing from S2 to S4 until it is determined in S3 that it is within the tolerance. As a result, the scanning trajectory of the excitation light detected in S2 is adjusted to be an ideal scanning trajectory as shown in FIG. Details of the process S4 for adjusting the scanning parameter will be described later.

  In S5, the CPU 108 obtains the correspondence between each sampling point and the pixel position (pixel address) of the endoscope image for the scanning trajectory adjusted in S4, and creates a new remapping table. Then, the created remapping table is stored in the CPU memory 110 together with the adjustment parameters adjusted in S4 (that is, the amplitude, phase, and frequency of the AC voltages X and Y), and the calibration program is terminated. In S5, the remap table and the adjustment parameter stored in the CPU memory 110 are repeatedly used until new calibration is performed.

  Next, details of the process S4 for adjusting the scanning parameter will be described. FIG. 13 is a flowchart showing an outline of the procedure of the process S4. The process S4 for adjusting the scanning parameter is a process S10 for adjusting the frequency f of the AC voltages X and Y (that is, the drive frequency f of the biaxial actuator 204C), and a process S20 for adjusting the phase difference between the AC voltage X and the AC voltage Y. , Processing S30 and S40 for adjusting the amplitudes of the AC voltage X and the AC voltage Y, processing S60 for obtaining a scanning trajectory and determining whether the shape and size are acceptable, and processing S70 for adjusting the settling period are included. After the shape and size of the scanning trajectory of the excitation light is adjusted by S10, S20, S30, and S40, it is determined whether or not the scanning trajectory is properly adjusted by S60, and after passing the determination of S60, S70 is performed. Is done.

  In the process of adjusting the amplitudes of the AC voltages X and Y, the process S30 for adjusting the overall size (specifically, the outermost peripheral part) and the shape of the spiral scan locus, and the spiral scan locus A process S40 for adjusting the interval between laps is included. The process S40 adjusts the magnitude of the drive voltage (the combined voltage of the AC voltage X and the AC voltage Y) as necessary for each revolution of the spiral, thereby making the interval between the spiral scanning trajectories substantially uniform, This is to prevent missing pixels. In step S30, since the amplitude of the outermost circumference of the scanning locus is adjusted to an appropriate value, pixel omission does not occur if the spacing between the spirals of the scanning locus becomes substantially uniform.

FIG. 14 is a flowchart for explaining the procedure of the process S40. In S40, the biaxial actuator 204C is first driven by the currently set scanning parameters, and the scanning trajectory for one cycle of the excitation light is acquired by the PSD 404 (S41). Next, the amplitude value for one round of the outermost circumference (Nth round) of the spiral scanning trajectory is extracted, and the average value r _N is calculated (S42). Further, the target value ΔR of amplitude change amount per one rotation of the scanning trajectory from the average value r _N is calculated. The target value ΔR of the amplitude change amount is calculated by the following calculation formula (S43).

  Next, the value of the counter n is set to the initial value 0 (S44). In the process S40, the drive voltage is adjusted one by one in turn from the innermost circumference of the spiral scanning trajectory, and the counter n is a parameter indicating the current adjustment target (n + 1th round).

Next, the value of the counter k is set to the initial value 0 (S45). As will be described later, in the present embodiment, the swirl interval of the scanning trajectory is adjusted so as to substantially match the target value for each round, but it is not possible to prevent pixel omission due to accumulated errors. Therefore, in this embodiment, whether or not the average value r _n of the amplitude of the scanning locus every predetermined cycle number K of scanning path (e.g., 50 weeks) are substantially coincident with the target value R _n is checked ( Determination S50 described later). The counter k is used to set a lap number interval for confirming the amplitude of the scanning trajectory.

Next, the n peripheral and amplitude values for each one rotation of the n + 1 round are extracted (S46), and the average amplitude r _n, from r n + _1, the amplitude change from the circumferential first n to (n + 1) -th revolution Δr _n is calculated (S47). Amplitude change amount [Delta] r _n is calculated by the following equation.

Next, whether the amplitude variation [Delta] r _n is the target value ΔR substantially match is determined (S48). Specifically, whether or not the value obtained by dividing the amplitude change amount [Delta] r _n in the target value [Delta] R [Delta] r n _/ [Delta] R (amplitude change amount that has been normalized) is within a predetermined range (e.g., 1 ± 0.1) , i.e., whether the amplitude change amount [Delta] r _n is within the range of the target value [Delta] R ± 10% is determined. If Δr _n / ΔR is out of the predetermined range (S48: NG), it is determined that the amplitude change amount Δr _n does not coincide with the target value ΔR, and the driving voltage for the (n + 1) _-th rotation is changed by the following calculation formula: (S52). That is, X% than larger amplitude change amount [Delta] r _n is the target value [Delta] R (smaller), the (n + 1) revolution of the AC voltage X, Y is (raised) lowered is X%, respectively.

但し、
Ｖ ： 変更前の第ｎ＋１周の駆動電圧
Ｖ’： 変更後の第ｎ＋１周の駆動電圧
Ｒ_ｎ＋１： 第ｎ＋１周の振幅の目標値
ｒ_ｎ＋１： 第ｎ＋１周の振幅の検出値

However,
V: Drive voltage of the (n + 1) th cycle before the change V ': Drive voltage of the (n + 1) th cycle after the change Rn _{+ 1} : Target value of the amplitude of the ( _{n + 1) th} cycle _{rn + 1} : Detected value of the amplitude of the (n + 1) th cycle

  When S52 is completed, the process returns to S41, and the process S4 for adjusting the scanning parameters is repeated from the beginning.

If Δr _n / ΔR is within the predetermined range (S48: OK), the amplitude change amount Δr _n substantially coincides with the target value ΔR, so that the driving voltage of the (n + 1) _-th rotation is not changed, and the process is S49. Proceed to

  In S49, it is determined whether or not the value of the counter k has reached the set value K. If the counter k has not reached the set value K (S49: NO), the counter k and the counter n are incremented (S53), the process returns to S46, and the amplitude change amount of the next round is adjusted. If the counter k has reached the set value K (S49: YES), the process proceeds to S50.

In S50, whether or not the average value r _n of the n-th circumference of the amplitude of the scanning locus is the target value R _n and substantially match is determined. Specifically, the n peripheral amplitude average value r _n a _(normalized amplitude) divided by r _{n /} R n at the target value R _n of a predetermined range of scanning locus (e.g., 1 ± 0. 1) whether or not the amplitude r _n is within the range of the target value R _n ± 10% is determined.

If r _n / _{R n} is it is outside the predetermined range (S50: NG), the amplitude _{r n} is determined not equal to the target value _{R n,} the determination of the amplitude change amount [Delta] r _n has been performed most recently For K laps (specifically, from the (n−k + 1) th to the (n + 1) th lap), in other words, for each lap after the lap in which the previous determination S50 was performed, The drive voltage is changed (S54).

  When S54 is completed, the process returns to S41, and the process S4 for adjusting the scanning parameters is repeated from the beginning.

r n _/ R _n is within a predetermined range, if the average value r _n of the n-th circumference of the amplitude of the scanning trajectory is substantially coincident with the target value R _n (S50: OK), the drive voltage is changed Instead, the process proceeds to S51. In S51, it is determined whether or not the counter n has reached a set value N (for example, 500 laps). If the counter n has not reached the set value N (S51: NO), the counter n is incremented (S55), the process returns to S45, and after the counter k is reset, the amplitude change amount of the next round is adjusted. Is done. If the counter n has reached the set value N (S51: YES), the process S4 ends.

  The value of the counter k can be set as appropriate, and the frequency of determining the amplitude of the scanning locus can be changed according to the value of the counter k. When the set value of the counter k is increased, the frequency of the scan locus amplitude determination S48 is reduced, so that the load on the CPU 108 can be reduced, but the accuracy of the amplitude of the scan locus is lowered. If the setting value of the counter k is decreased, the determination S48 of the amplitude of the scanning locus is frequently performed, so that the accuracy of the amplitude of the scanning locus increases, but the load on the CPU 108 increases.

  By the process S40 described above, the interval of the spiral trajectory of the scanning light by the confocal optical unit 204 (optical scanning device) is adjusted to an appropriate range. As a result, when an image is captured using the confocal optical unit 204, pixel omission extending in the circumferential direction as shown in FIG. 15 is prevented.

  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 above embodiment, the interval (amplitude change amount) of the optical scanning locus detected by the PSD is compared with the target value, and the drive amount (drive voltage) of the actuator is adjusted based on the comparison result. Although the configuration is adopted, the configuration may be such that the optical scanning trajectory is compared with the target value and the drive amount of the actuator is adjusted based on the trajectory comparison result.

  In the present embodiment, the CPU 108 has been described as executing the calibration program. However, the present invention is not limited to this configuration, and the calibration circuit 412 may execute the calibration program. In this case, the calibration circuit 412 is configured to control the biaxial actuator 204C, change adjustment parameters, and the like by communication with the CPU 108.

  In addition, the confocal optical unit 204 of the present embodiment is configured to be incorporated in the distal end portion of the confocal endoscope 200. However, the confocal optical unit 204 is inserted into a treatment instrument insertion channel of the endoscope, for example. And may be incorporated into a confocal probe to be used.

  Further, the position detection element mounted on the calibration apparatus 400 is not limited to PSD. The PSD 404 may be replaced with another element capable of detecting the position and light quantity, such as a CCD (Charge Coupled Device) or an array type PMT (Photomultiplier Tube).

1 Scanning Confocal 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 204 Confocal optical unit 206 Sub CPU
208 Sub Memory 210 Scan Driver 400 Calibration Device 402 Case 404 PSD
405 PSD board 406 Relay lens unit 408 XYZ stage 410 Stage drive motor 412 Calibration circuit

Claims (11)

An optical fiber that guides light emitted from a light source, and an actuator that cantilever-supports the tip of the optical fiber and vibrates the optical fiber in two radial directions that are orthogonal to each other, the X-axis direction and the Y-axis direction And control means for controlling the driving of the actuator in the X-axis direction and the Y-axis direction based on predetermined scanning parameters so that the light emitted from the tip of the optical fiber is scanned in a spiral trajectory And a scanning trajectory detecting means for detecting a scanning trajectory of the scanning light emitted from the tip of the optical fiber, and a scanning endoscope system comprising an optical scanning device that periodically performs spiral optical scanning Calibration method,
The control means driving the actuator based on the scanning parameter to perform the spiral optical scanning;
The scanning trajectory detecting means detecting a trajectory of the spiral optical scanning;
An adjustment step in which the control means adjusts the scanning parameters so that the spiral optical scanning locus detected by the scanning locus detecting means substantially coincides with a target locus;
Including
The adjusting step includes a trajectory interval adjusting step of changing the drive amount of the actuator to adjust the interval of the trajectory of the spiral optical scanning to be substantially constant.
A scanning endoscope system calibration method characterized by the above. The trajectory interval adjustment step includes a step of determining an interval of the target trajectory from the detected spiral optical scanning trajectory.
The method of calibrating a scanning endoscope system according to claim 1. The step of determining the interval of the target trajectory includes:
Calculating an average amplitude r _N of the outermost trajectory from the detected spiral optical scanning trajectory;
Determining a value r _N / N obtained by dividing the average amplitude r _N of the outermost track by the number N of turns of the spiral target track as an interval ΔR of the target track.
The method for calibrating a scanning endoscope system according to claim 2. The locus interval adjustment step includes:
Calculating a neighboring track spacing [Delta] r _n n-th circumference and a distance between the first n + 1 lap trajectory from the trajectory of the detected spiral optical scanning,
A first drive amount adjustment step of adjusting the drive amount V _{n + 1} of the actuator when the optical scan of the (n + 1) th round is performed so that the adjacent locus interval substantially matches the interval of the target locus.
The method for calibrating a scanning endoscope system according to any one of claims 1 to 3, wherein: Calculating the adjacent trajectory interval;
Calculating an average amplitude r _n and r _{n + 1} of the n peripheral and the n + 1 round trajectory from the trajectory of the detected spiral optical scanning,
Comprising the steps of: a mean amplitude _{r n} and the difference _{r n} + 1 -r _n the adjacent track spacing [Delta] r _n and the average amplitude _{r n + 1} of the (n + 1) -th revolution locus of the first n circumferential trajectory,
The method for calibrating a scanning endoscope system according to claim 4. In the first drive amount adjustment step, the drive amount of the actuator when the optical scanning of the (n + 1) th round is performed only when the error of the adjacent locus interval with respect to the target locus interval exceeds the first tolerance. V _{n + 1} is adjusted,
The method for calibrating a scanning endoscope system according to claim 4 or 5, wherein: The first drive amount adjustment step includes:
Obtaining a target trajectory amplitude R _{n + 1} that is an amplitude of the (n + 1) -th turn of the target trajectory;
Obtaining a detected trajectory amplitude rn _{+ 1} which is an amplitude of the detected n + 1-th turn of the spiral optical scanning trajectory;
Adjusting the driving amount V _{n + 1} of the actuator to V _{n + 1} ′ when the optical scanning of the (n + 1) th round is performed according to the following calculation formula:

The method for calibrating a scanning endoscope system according to any one of claims 4 to 6, wherein: An amplitude error determination step for determining whether an error in amplitude of the detected spiral-shaped optical scanning locus with respect to the target locus is within a second tolerance for each predetermined round of the spiral locus. Including,
The method for calibrating a scanning endoscope system according to any one of claims 1 to 7, wherein the method is calibrated.   Only when the amplitude error exceeds a second tolerance in the amplitude error determination step, the detected spiral-shaped optical scanning trajectory for each turn after the previous round of the amplitude error determination step. The method further comprises a second drive amount adjustment step of adjusting the drive amount of the actuator when the optical scanning of each round is performed so that the amplitude of the actuator substantially coincides with the amplitude of the target locus. 9. A calibration method for a scanning endoscope system according to 8. The second drive amount adjustment step includes:
Obtaining a target trajectory amplitude R _n which is an amplitude of the nth round of the target trajectory;
Obtaining a detection trajectory amplitude r _n is the n th division of the amplitude of the trajectory of the detected spiral optical scanning,
Adjusting the drive amount V _{n of the} actuator to V _n ′ when the nth optical scanning is performed according to the following calculation formula:

The method for calibrating a scanning endoscope system according to claim 9. An optical fiber that guides light emitted from a light source, and an actuator that cantilever-supports the tip of the optical fiber and vibrates the optical fiber in two radial directions that are orthogonal to each other, the X-axis direction and the Y-axis direction And control means for controlling the driving of the actuator in the X-axis direction and the Y-axis direction based on predetermined scanning parameters so that the light emitted from the tip of the optical fiber is scanned in a spiral trajectory And a scanning trajectory detecting means for detecting a scanning trajectory of the scanning light emitted from the tip of the optical fiber, and a scanning endoscope system comprising an optical scanning device that periodically performs spiral optical scanning Because
The control means is
Means for driving the actuator based on the scanning parameters to perform the spiral optical scanning;
Adjusting means for performing processing for adjusting the scanning parameters so that the spiral optical scanning locus detected by the scanning locus detecting means substantially coincides with a target locus;
With
The adjusting unit includes a trajectory interval adjusting unit that adjusts an interval of the trajectory of the spiral optical scanning to be substantially constant by changing a driving amount of the actuator.
A scanning endoscope system characterized by the above.

Images