JP2014018556A - Calibration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a calibration apparatus for a scanning confocal endoscope system capable of easily checking an irradiation position of illumination light.SOLUTION: The calibration apparatus for a scanning confocal endoscope system comprises: a relay lens that enlarges a scanning area of excitation light exited from an optical scanner; light detection means that detects a scanning trajectory of the excitation light exited from the relay lens; a fluorescence emitter that emits fluorescence when the excitation light enters; moving means that moves the relay lens and the light detection means relative to the optical scanner; and correction means that corrects scanning parameters of the excitation light such that the detected scanning trajectory become a reference scanning trajectory. The relay lens is arranged such that a rear focal point substantially matches a center position of a light-receiving surface. The moving means moves the relay lens and the light detection means such that, on the basis of the fluorescence displayed on a confocal image, a front focal point of the relay lens substantially matches a converging point of the excitation light and the scanning area of the excitation light is within the light-receiving surface.

Description

  The present invention includes an optical scanning device that emits excitation light of a predetermined wavelength to a subject and periodically scans within a predetermined scanning range, and emits fluorescence generated from the subject excited by the excitation light emitted from the optical scanning device. The present invention relates to a calibration apparatus for a scanning confocal endoscope system that receives light and displays a confocal image.

  2. Description of the Related Art Conventionally, there is known a scanning endoscope system that scans light guided by an optical fiber in a spiral shape with respect to an observation site and receives reflected light from the observation site to form an image (for example, a patent) Reference 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 amplitude of vibration, 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.

  In recent years, it has also been proposed to apply a scanning endoscope system as described in Patent Document 1 to a scanning confocal endoscope system (for example, Patent Document 2). A scanning confocal endoscope system irradiates a living tissue to which a drug is administered with a laser beam, and among the fluorescence emitted from the living tissue, a pin arranged at a position conjugate to the focal position of the confocal optical system By extracting only the components through the holes, the living tissue can be observed at a higher magnification than an observation image obtained by a normal endoscope optical system. The scanning confocal endoscope system described in Patent Document 2 is an observation image obtained by a normal endoscope optical system by scanning a specific narrow region of a living tissue two-dimensionally or three-dimensionally with a laser beam. It is configured to be able to observe a minute object that cannot be observed at a magnification of 1, or to observe a tomographic part of a living tissue.

  In the system described in Patent Document 1 or 2, reflected light or fluorescence from a scanning region (observation site) is received at a predetermined cycle timing (hereinafter referred to as “sampling points”), and at each sampling point. Luminance information is assigned to the display coordinate system of the monitor (the pixel position of the endoscopic image), and a two-dimensional endoscopic image is displayed. 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, in this type of scanning endoscope system, calibration is performed so that an ideal scanning pattern can be obtained while monitoring an actual scanning pattern (scanning trajectory) (Patent Document 1). .

Special table 2008-514342 gazette JP 2011-255015 A

  The scanning endoscope system described in Patent Document 1 receives illumination light emitted from an optical fiber by a PSD (Position Sensitive Detector), and detects the position of an irradiation spot in a scanning pattern (scanning trajectory). Calibration (calibration) is performed so as to obtain an ideal scanning pattern by adjusting the amplitude, phase, frequency, and the like of the voltage applied to the biaxial actuator. However, such a method is used in a scanning endoscope system configured to scan a relatively wide scanning region (for example, a scanning region having a diameter of 10 mm) as in the scanning endoscope system described in Patent Document 1. Is effective, but a scanning confocal endoscope system configured to scan a narrow scanning region (for example, a scanning region having a diameter of 500 μm) as in the scanning confocal endoscope system described in Patent Document 2 However, there is a problem that the position of the irradiation spot cannot be accurately detected due to the resolution limit of the PSD sensor.

  Further, in the calibration of the scanning pattern, the optical fiber is accurately set with respect to the PSD so that the illumination light scans on the PSD light-receiving surface (that is, the scanning locus is included in the PSD light-receiving surface). Positioning is important. The positions of the optical fiber and the PSD can be automatically adjusted based on, for example, the position information of the irradiation spot obtained by the PSD. However, a part of the scanning locus deviates from the light receiving surface of the PSD at the time of position adjustment. In such a case, since the position information of the irradiation spot may not be obtained accurately, a configuration that allows visual confirmation is desired.

  The present invention has been made in view of the above circumstances, and an object thereof is to determine the position of an irradiation spot in a scanning pattern even in a scanning endoscope system configured to scan a narrow scanning region. It is an object of the present invention to provide a calibration device capable of accurately detecting and calibrating so as to obtain an ideal scanning pattern and easily confirming the irradiation position of illumination light.

  In order to achieve the above object, a calibration device according to the present invention includes an optical scanning device that periodically scans excitation light of a predetermined wavelength from a light source on a subject within a predetermined scanning range. A calibration device for a scanning confocal endoscope system that receives fluorescence generated from a subject excited by emitted excitation light and displays a confocal image, and the excitation light emitted from the optical scanning device is incident on the calibration device. The scanning lens on the light receiving surface of the received excitation light is received by a relay lens that expands the scanning range, and excitation light emitted from the relay lens is received by a light receiving surface arranged perpendicular to the optical axis of the relay lens. A light detecting means for detecting, a fluorescent light emitting element which is disposed at a position optically equivalent to the light receiving surface and emits fluorescence when excitation light emitted from the relay lens is incident, a relay lens and a light detecting hand And a correction unit for correcting the scanning parameter of the excitation light emitted from the optical scanning device so that the scanning locus detected by the light detection unit becomes the reference scanning locus. The relay lens is arranged so that the rear focal point of the relay lens substantially coincides with the center position of the light receiving surface, and the moving means is a fluorescent light-emitting body displayed in the confocal image. Based on the fluorescence, the position of the front focal point of the relay lens substantially coincides with the condensing point of the excitation light emitted from the optical scanning device, and the scanning range of the excitation light emitted from the relay lens is within the light receiving surface. The relay lens and the light detection means are moved.

  According to such a configuration, the scanning trajectory of the light emitted from the optical scanning device is enlarged and received on the light detection means to the extent that it is not affected by the resolution, so that a narrow scanning region is scanned. This scanning endoscope system can detect the scanning trajectory with high accuracy, and can be calibrated to be an ideal scanning trajectory. In addition, by confirming the fluorescence generated when the excitation light enters the fluorescent light emitter on the confocal image, it is easy to determine whether the scanning range of the excitation light emitted from the relay lens is within the light receiving surface. It becomes possible to confirm.

  In addition, the fluorescent light emitter includes an indicator portion that is formed at a position equivalent to the center of the light receiving surface and emits fluorescence, and the moving unit is configured such that the center of the scanning range of the excitation light emitted from the relay lens is the center of the light receiving surface. The relay lens and the light detection means can be moved so as to substantially match. According to such a configuration, the scanning locus of the excitation light emitted from the relay lens can be detected at the center portion of the light receiving surface with stable position detection accuracy.

  In addition, it is desirable that the index portion is a cross-shaped index formed by two straight lines that are orthogonal to the optical axis of the relay lens at a position equivalent to the center of the light receiving surface and are orthogonal to each other. In this case, it is preferable that the cross-shaped index is formed by a solid line or a broken line. The indicator unit may include a plurality of indicators having a predetermined shape discretely arranged in a plane equivalent to the light receiving surface.

  Further, the index unit can include a distance index indicating a distance from the center of the light receiving surface. In this case, the distance index is preferably a scale-shaped index formed so as to be orthogonal to the cross-shaped index in accordance with the distance from the center of the light receiving surface. The distance index may be an index having a different shape according to the distance from the center of the light receiving surface. According to such a configuration, the size of the scanning range of the excitation light emitted from the relay lens can be confirmed on the confocal image.

  Further, the fluorescent light emitter includes a frame portion formed so as to surround the periphery of the light receiving surface at a position equivalent to the light receiving surface, and the moving means prevents the scanning range of the excitation light emitted from the relay lens from being applied to the frame portion. In addition, the relay lens and the light detection means can be moved.

  In addition, the fluorescent light emitter can be configured to cover the light receiving surface and the periphery of the light receiving surface at a position equivalent to the light receiving surface and to transmit a part of the excitation light incident from the relay lens. In this case, the fluorescent light emitter may be configured to include an indicator portion that does not emit fluorescence formed by two straight lines orthogonal to each other at a position equivalent to the center of the light receiving surface. In addition, the fluorescent light emitter is preferably formed in a grid shape. According to such a configuration, since it is possible to observe the fluorescence regardless of the position of the scanning range of the excitation light on the light receiving surface, it is very easy to align the optical scanning device and the light detection means. Become.

  Further, the light detection means may include a cover glass on the front surface of the light receiving surface, and the fluorescent light emitter may be coated on a surface facing the light receiving surface of the cover glass. In this case, a fluorescent reflection coating that reflects the fluorescence generated by the fluorescent light emitter may be formed on the fluorescent light emitter. According to such a configuration, since the fluorescence from the fluorescent light emitter can be prevented from entering the light receiving surface, the light detection unit can detect the position of the excitation light incident on the light receiving surface with high accuracy. .

  In addition, it is arranged between the relay lens and the light detection means, and splits the excitation light incident through the relay lens and emits it to the light detection means and the fluorescent light emitter, and at the same time, the fluorescence emitted by the fluorescent light emitter is relay lens. A beam splitter can be provided that reflects toward the.

  The scanning parameter is at least one of a first parameter for expanding or reducing the scanning range of the scanning light, a second parameter for changing the shape of the scanning range of the scanning light, and a third parameter for changing the scanning speed of the scanning light. One can be included.

  Further, it may be configured to have a remapping table creating means for sampling the scanning locus of the enlarged scanning light corrected by the correcting means at a predetermined timing and assigning two-dimensional raster coordinates to each sampling point.

  Moreover, it can be set as the structure which accommodates a relay lens, a photon detection means, and a fluorescence light-emitting body in a single housing | casing. In this case, the housing is preferably a shielding housing that shields the light detection means from outside light. According to such a configuration, the influence of external light can be eliminated, so that the scanning trajectory of the scanning light can be detected with a high SN ratio.

  According to the calibration apparatus of the present invention, even in a scanning endoscope system configured to scan a narrow scanning region, the position of an irradiation spot in the scanning pattern is accurately detected, and an ideal scanning pattern is obtained. It can be calibrated as obtained, and the irradiation position of the illumination light can be easily confirmed.

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 front view of PSD of the embodiment of the present 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 positional relationship of the scanning area | region of excitation light, and PSD. It is a figure which shows a mode that the center of a scanning area | region moves to the center of PSD. It is a figure which shows the modification of the fluorescent substance of embodiment of this invention. It is a figure which shows the modification of the fluorescent substance of embodiment of this invention. It is a figure which shows the modification of the fluorescent substance of embodiment of this invention. It is a figure which shows the modification of the fluorescent substance of embodiment of this invention. It is a figure which shows the modification of the fluorescent substance of embodiment of this invention. It is a figure which shows the modification of the calibration apparatus of this embodiment.

  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.

  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. In this embodiment, fluorescein is assumed as a fluorescent dye to be administered to a patient, and the excitation light is laser light having a wavelength of 488 nm.

  The proximal end of the optical fiber 202 is optically coupled to the optical demultiplexer / multiplexer 104 through the optical connector 152. The distal end of the optical fiber 202 is housed in a confocal optical unit 204 built into the distal end portion 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. 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, the central axis AX indicates the axis of the optical fiber 202 arranged in the Z direction. When the tip 202a of the optical fiber 202 is not oscillating, the central axis AX is , Which coincides with the optical path of the optical 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 resonate the piezoelectric body in the X direction, and also applies 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 resonates 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 is composed of one sampling period and one braking period, and the frame rate can be adjusted by adjusting the settling period. 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. 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 clamped 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. The CPU 108 obtains the pixel position (raster coordinates) of the endoscope image corresponding to each sampling point based on the relationship shown in FIG. 5 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. In addition, since the product-specific characteristics change with time due to the environmental temperature and the like, even if an ideal scanning trajectory is obtained once, it is not maintained. 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 confocal 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 a well-known two-dimensional optical position detection sensor, which is mounted on the PSD substrate 405 and 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). Has been. 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 404a). 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 therein, and its optical axis passes through the center of the light receiving surface 404a of the PSD 404, and the rear focal point F2 is at the center of the light receiving surface 404a of the PSD 404. It is arranged to be located. 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. The magnification of the relay lens unit 406 is determined by comprehensively considering various factors such as the size of the scanning region of the excitation light, the size of the PSD 404, and the position detection resolution of the PSD 404. Here, assuming a normally available PSD, the relay lens unit 406 has a position detection resolution such that the size of the scanning area enlarged by the relay lens unit 406 is 1 mm or more on the light receiving surface of the PSD 404. It is desirable to set the magnification. Further, from the viewpoint of the device size and response speed, it is desirable to use the PSD 404 having the smallest light receiving surface 404a. Therefore, the magnification of the relay lens unit 406 takes into account the position detection resolution and the device size. For example, it is preferable to set to about 2 to 20 times. Therefore, in the present embodiment, the diameter of the scanning region of the excitation light emitted from the confocal optical unit 204 (that is, the maximum fluctuation width at the condensing position of the excitation light) is 500 μm, and the size of the PSD 404 that is normally available, Assuming position detection resolution and response speed, the magnification of the relay lens unit 406 is set to 10 times. Accordingly, the scanning locus of the excitation light emitted from the confocal optical unit 204 is enlarged by the relay lens unit 406 and scanned so as to draw a circle having a diameter of 5 mm at the maximum on the light receiving surface 404 a of the PSD 404. 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. When excitation light enters the light receiving surface 404 a of the PSD 404, a detection current corresponding to the position of the excitation light is generated, and this detection current is output to the calibration circuit 414 via the PSD substrate 405.

  FIG. 7 is a front view of the PSD 404 of the present embodiment. The PSD 404 includes a rectangular light receiving surface 404a at the center, and the light receiving surface 404a is sealed with a cover glass 404b (FIG. 6). Further, the surface of the cover glass 404b facing the light receiving surface 404a is sequentially coated with a phosphor 404c (for example, sialon phosphor) that emits fluorescence by excitation light having a wavelength of 488 nm and a fluorescent reflection coating 404d. Yes. In the present embodiment, these coatings are sufficiently thin, and the light receiving surface 404a, the phosphor 404c, and the fluorescent reflection coating 404d are considered to be disposed on substantially the same plane.

  As shown in FIG. 7, the phosphor 404c includes a frame-shaped portion 404ca disposed so as to surround the periphery of the light receiving surface 404a, and a cross-shaped index portion 404cb disposed at the center of the light receiving surface 404a. ing. At the time of calibration, when excitation light enters the phosphor 404c, the generated fluorescence enters the tip 202a of the optical fiber 202 and is displayed on the monitor 300 as an endoscopic image. Note that the light receiving surface 404a of the PSD 404 is sufficiently larger than the scanning region (diameter 5 mm) of the excitation light, and in the present embodiment, the PSD 404 having a light receiving surface size of 10 mm × 10 mm is used. Further, the line widths of the two vertical and horizontal lines constituting the indicator portion 404cb are sufficiently narrow so as not to affect the remapping, and in this embodiment, the line width is set to about 10 μm.

  The fluorescent reflection coating 404d is a coating for reflecting the fluorescence generated by the indicator portion 404cb. As described above, the fluorescent reflection coating 404d is disposed between the phosphor 404c and the light receiving surface 404a, and all the fluorescence generated by the indicator 404cb is reflected to the optical fiber 202 side. Therefore, the fluorescence generated by the indicator portion 404cb does not enter the light receiving surface 404a, and the PSD 404 detects the excitation light from the confocal optical unit 204 with a high SN ratio. Further, as described above, the frame-shaped portion 404ca of the phosphor 404c is disposed so as to surround the periphery of the light-receiving surface 404a. Therefore, when the excitation light deviates from the light-receiving surface 404a, the frame-shaped portion 404ca Fluorescence will be generated. However, since all the fluorescence generated in the frame-shaped portion 404ca is also reflected by the fluorescent reflection coating 404d toward the optical fiber 202, the excitation light or the fluorescence is incident on the electrode of the PSD 404 disposed around the light receiving surface 404. There is no. Accordingly, the PSD 404 detects the position of the excitation light incident on the light receiving surface 404a with high accuracy without the stray light from the electrodes around the PSD 404 entering the PSD 404.

  The case 402 is fixed on an XYZ stage 408 that can move in the X, Y, and Z directions by the operation of the position adjustment knob 410 by the user (FIG. 6). During calibration, which will be described later, the user operates the position adjustment knob 410 to relatively position the confocal optical unit 204 fixed to the unit support 420 and the case 402 (that is, the relay lens unit 406 and the PSD 404). Adjust the relationship.

  The calibration circuit 412 is a circuit capable of bidirectional communication with the CPU 108. The calibration circuit 412 converts the detection current of the PSD 404 output from the PSD substrate 405 into a voltage at the time of calibration, and outputs it to the CPU 108 as a detection voltage.

  FIG. 8 is a flowchart of a calibration program executed during calibration. The calibration program is a subroutine executed by the CPU 108 when the user inserts the confocal 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. . 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. 8, when the calibration program is started, the CPU 108 executes S <b> 11 and drives the confocal optical unit 204. Specifically, the CPU 108 controls the light source 102 so that the excitation light is continuously emitted, and controls the scanning driver 210 to apply predetermined AC voltages X and Y to the biaxial actuator 204C. Here, the predetermined AC voltages X and Y mean the AC voltages X and Y adjusted by the previous calibration when there is the previous calibration data, and there is no previous calibration data. In the case (for example, in the case of calibration at the time of assembly in a factory), it means the predetermined reference (default) AC voltages X and Y. As described above, when the predetermined AC voltages X and Y are applied to the biaxial actuator 204C, the tip 202a of the optical fiber 202 rotates according to the applied AC voltages X and Y. Excitation light emitted from the optical fiber 202 passes through the relay lens unit 406 and rotationally scans on the light receiving surface 404 a or the phosphor 404 c of the PSD 404. When excitation light enters the phosphor 404c, the generated fluorescence enters the tip 202a of the optical fiber 202, is detected by the light receiver 114, and is displayed on the monitor 300 as an endoscopic image. Next, the process proceeds to S12.

  In S12, the CPU 108 determines whether or not the PSD position adjustment by the user is completed. In order for the PSD 404 to accurately detect the scanning trajectory of the excitation light emitted from the confocal optical unit 204, the scanning trajectory of the excitation light needs to be within the light receiving surface 404 a of the PSD 404. However, due to the attachment position error when the focal optical unit 204 is attached to the unit support 420 and the influence of product-specific characteristics, the scanning trajectory of the excitation light is not necessarily obtained simply by attaching the confocal optical unit 204 to the unit support 420. Does not always fit within the light receiving surface 404a of the PSD 404. Therefore, in the present embodiment, the user can visually confirm the position of the scanning locus of the excitation light on the light receiving surface 404 a of the PSD 404, and the light receiving surface 404 a so that the scanning locus of the excitation light is within the light receiving surface 404 a of the PSD 404. The position of can be adjusted.

  Specifically, the user operates the position adjustment knob 410 while viewing the endoscopic image displayed on the monitor 300 to move the case 402 in the Z direction with respect to the confocal optical unit 204. And it adjusts so that the fluorescence which generate | occur | produced in the fluorescent substance 404c is displayed on the monitor 300 as an endoscopic image. As described above, since the light receiving surface 404a and the phosphor 404c are arranged on substantially the same plane, when the fluorescence generated by the phosphor 404c is displayed on the monitor 300 as an endoscopic image, light is emitted. The tip 202a of the fiber 202 is accurately disposed at the front focal position of the objective optical system 204D, and is optically conjugate with the light receiving surface 404a. FIG. 9 is a diagram illustrating the positional relationship between the scanning region A of the excitation light and the PSD 404 when the tip 202a of the optical fiber 202 is disposed at the front focal position of the objective optical system 204D. As shown in FIG. 9, the scanning area A of the excitation light does not necessarily coincide with the center of the PSD 404 due to the attachment position error when the confocal optical unit 204 is attached to the unit support 420 and the influence of the product specific characteristics. When the tip 202a of the optical fiber 202 is disposed at the front focal position of the objective optical system 204D, from the phosphor 404c in the scanning region A (in FIG. 9, the frame-like portion 404ca around the upper right of the light receiving surface 404a). Fluorescence is generated and observed on the monitor 300.

  Next, the user operates the position adjustment knob 410 while viewing the endoscopic image (that is, the fluorescent image in the scanning area A) displayed on the monitor 300, and moves the case 402 to the confocal optical unit 204. And move in the Y direction. Then, the case 402 is moved so that the fluorescence from the indicator portion 404cb is displayed on the monitor 300, and the center of the scanning area A is adjusted to substantially coincide with the center of the PSD 404 (that is, the center of the indicator portion 404cb). To do. FIG. 10 is a diagram illustrating how the center of the scanning area A moves to the center of the PSD 404. In the case of FIG. 10, the user moves the center of the scanning region A to the center of the PSD 404 by moving the confocal optical unit 204 diagonally upward to the right based on the fluorescence image displayed on the monitor 300. When the center of the scanning region A is adjusted so as to substantially coincide with the center of the PSD 404 (that is, the center of the indicator portion 404cb), the center axis AX (the axis of the optical fiber 202 arranged in the Z direction) and the relay lens The optical axis of the unit 406 substantially coincides, and the monitor 300 observes the cross-shaped fluorescence generated in the indicator portion 404cb.

  In this manner, in S12, the user operates the position adjustment knob 410 while viewing the endoscopic image displayed on the monitor 300, and moves the case 402 in the XYZ directions with respect to the confocal optical unit 204. Then, adjustment is made so that the scanning locus of the excitation light is positioned at the center of the light receiving surface 404a of the PSD 404, and after the adjustment, predetermined input is performed from a user interface (not shown) of the system main body 100. The CPU 108 waits until a predetermined input from the user is received (S12: NO). When the CPU 108 receives the predetermined input from the user, the CPU 108 determines that the PSD position adjustment by the user has been completed (S12: YES), and the process is as follows. Proceed to S15.

  In S <b> 15, the CPU 108 detects the scanning trajectory of excitation light that scans the light receiving surface of the PSD 404 in a spiral shape. Specifically, the CPU 108 detects the current output from each electrode of the PSD 404 at a predetermined timing, performs a known calculation based on the detected current, and calculates the spot formation position of the excitation light on the PSD 404. As described above, since the scanning confocal endoscope system 1 has product-specific characteristics, an ideal scanning trajectory is not obtained in a state where the predetermined AC voltages X and Y in S11 are applied. The area A becomes a scanning locus that is larger or smaller than 5 mm in diameter or distorted in an elliptical shape. Next, the process proceeds to S16.

  In S16, the CPU 108 evaluates the scanning trajectory of the excitation light detected in S15, 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 S15. To evaluate. In S16, when it is determined that it is within the tolerance (S16: YES), the process proceeds to S18, and when it is determined that it is not within the tolerance (S16: NO), the process proceeds to S17.

  In S17, the CPU 108 changes adjustment parameters (scanning parameters) of the AC voltages X and Y applied to the biaxial actuator 204C. Specifically, based on the evaluation result of the scanning trajectory of excitation light in S16, the CPU 108 adjusts the amplitudes of the AC voltages X and Y when there is a problem with the size of the scanning area, and expands the scanning area. Or reduce. If there is a problem with the shape of the scanning region, the shape of the scanning region is changed by adjusting the phases of the AC voltages X and Y. If there is a problem with the scanning speed of the scanning area, the frequency of the alternating voltages X and Y is adjusted to change the scanning speed of the excitation light. The CPU 108 repeatedly executes the processing from S15 to S17 until it is determined in S16 that it is within the tolerance. As a result, the scanning locus of the excitation light detected in S15 is adjusted to be an ideal scanning locus.

  In S18, the CPU 108 creates a new remapping table by obtaining the correspondence between each sampling point and the pixel position (pixel address) of the endoscope image for the scanning trajectory adjusted in S17. Then, the created remapping table is stored in the CPU memory 110 together with the adjustment parameters adjusted in S17 (that is, the amplitude, phase, and frequency of the AC voltages X and Y), and the calibration program is terminated. In S18, the remap table and the adjustment parameter stored in the CPU memory 110 are repeatedly used until new calibration is performed.

  Thus, in the calibration of this embodiment, the scanning locus of the excitation light emitted from the confocal optical unit 204 is enlarged by the relay lens unit 406 and received by the PSD 404. Further, the phosphor 404c is coated on the PSD 404, and the user views the endoscopic image (that is, the fluorescent image in the scanning region A) displayed on the monitor 300 while the scanning region A is in the PSD 404. It can be adjusted to be positioned at the center of the light receiving surface 404a. Accordingly, the scanning trajectory of the excitation light emitted from the confocal optical unit 204 is enlarged to the extent that it is not affected by the resolution of the PSD 404, and is reliably received on the light receiving surface 404a of the PSD 404. That is, even in a scanning endoscope system configured to scan a narrow scanning region, such as the scanning confocal endoscope system 1 of the present embodiment, the scanning trajectory of the scanning light is highly accurate and It is possible to reliably detect, and further, calibration (adjustment) can be performed so that an ideal scanning locus is obtained.

  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 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 change adjustment parameters and the like by communication with the CPU 108.

  In addition, although the magnification of the relay lens unit 406 of this embodiment is 10 times, as described above, the magnification of the relay lens unit 406 can be set to about 2 to 20 times, and excitation on the PSD 404 is performed. By enlarging the scanning region of the light within a range that fits on the light receiving surface 404 of the PSD 404, it becomes possible to detect the scanning locus of the excitation light more accurately.

  A system to which the present invention is applicable is not limited to the scanning confocal endoscope system described in the present embodiment. For example, the present invention can also be applied to a scanning confocal endoscope system that employs a raster scanning method that reciprocally scans the horizontal direction of the scanning region, a Lissajous scanning method that scans the scanning region sinusoidally, and the like.

  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).

  In the calibration according to the present embodiment, the user operates the position adjustment knob 410 while viewing the endoscopic image displayed on the monitor 300, and moves the case 402 in the XYZ directions with respect to the confocal optical unit 204. Although described as a configuration to be moved, it is not limited to this configuration. For example, the XYZ stage 408 is moved by a motor, and the CPU 108 automatically adjusts the position so that the scanning locus of excitation light is positioned at the center of the light receiving surface 404a of the PSD 404 while performing image processing on the acquired fluorescent image. Also good.

  Moreover, although the phosphor 404c of this embodiment was formed by coating the back surface side (light-receiving surface 404a side) of the cover glass 404b, it is not limited to this structure. Any frame that emits fluorescence by excitation light having a wavelength of 488 nm may be used. For example, the frame-shaped portion 404ca is formed by attaching a yellow cloth containing a fluorescent paint (a cloth that emits yellow fluorescence) to the cover glass 404b. can do. The indicator portion 404cb can be formed by putting a marking line on the back side of the cover glass 404b and applying a fluorescent paint in the marking line.

  The frame portion 404ca of the phosphor 404c of this embodiment is formed so as to surround the periphery of the light receiving surface 404a of the PSD 404. For example, the position detection accuracy of the peripheral portion of the light receiving surface 404a is low, and the light receiving surface 404a When an effective detection area is set in the center, the area other than the effective detection area may be masked. According to such a configuration, the PSD 404 can be used only in an area where the position detection accuracy is high, so that more accurate calibration is possible.

  In this embodiment, the fluorescent reflection coating 404d is applied on the coating of the phosphor 404c. However, when the fluorescence generated by the indicator 404cb does not affect the position detection of the excitation light by the PSD 404, the fluorescence reflection coating 404d is applied. The reflective coating 404d can be omitted.

  In the present embodiment, the phosphor 404c has been described as including the frame-shaped portion 404ca and the indicator portion 404cb. For example, the light-receiving surface 404a of the PSD 404 is sufficiently large, and the confocal optical unit 204 is Even if the attachment position error when attached to the unit support 420 and the influence of the product-specific characteristics are taken into account, if the scanning locus of the excitation light always falls within the light receiving surface 404a of the PSD 404, the indicator portion 404cb is necessarily provided. There is no. In this case, as shown in FIG. 11, the user views the endoscopic image (that is, the fluorescent image in the scanning region A) displayed on the monitor 300 so that the scanning trajectory A is not applied to the frame-shaped portion 404ca. While operating the position adjustment knob 410, the case 402 is moved in the X and Y directions. However, in the case of such a configuration, when normal adjustment is performed, no fluorescence from the phosphor 404c is observed on the monitor 300. Therefore, for example, as shown in FIG. 12, the amplitude of the alternating voltages X and Y is once increased to enlarge the scanning locus A, and the calibration is performed after confirming the fluorescence of the frame-shaped portion 404ca. Also good.

  Moreover, although the index part 404cb of the phosphor 404c of the present embodiment has been described as a cross-shaped index composed of two vertical and horizontal lines, the present invention is not limited to this configuration, and indexes of various shapes are used. be able to. FIG. 13 is a diagram showing a modification of the indicator portion 404cb of the phosphor 404c of the present embodiment. FIG. 13A is a diagram in which two vertical and horizontal lines constituting the index unit 404cb of the present embodiment are each divided into a predetermined number and changed to a broken-line index unit 404cb1. With this configuration, the diameter of the scanning region A is confirmed by counting the number of broken lines on the endoscopic image (that is, the fluorescent image in the scanning region A) displayed on the monitor 300. Is possible. As shown in FIG. 13B, the indicator portion 404cb may include a scale (distance indicator) provided at a predetermined position so as to be orthogonal to each line. According to such a configuration, the diameter of the scanning region A can be easily known from the endoscopic image displayed on the monitor 300. Further, as shown in FIG. 13C, the indicator portion 404cb can be configured by discretely arranging circular marks, for example. In this case, it is desirable that the mark is formed of a mark indicating the center of the light receiving portion 404a and a plurality of marks indicating the distance from the center of the light receiving portion 404a. In addition, it is desirable that the plurality of marks indicating the distance from the center of the light receiving unit 404a have different shapes depending on the distance from the center of the light receiving unit 404a.

  In the present embodiment, the phosphor 404c has been described as being configured by the frame-shaped portion 404ca and the indicator portion 404cb. However, the present invention is not limited to this configuration. 14 and 15 are diagrams showing a modification of the phosphor 404c of the present embodiment. As shown in FIG. 14, for example, instead of the phosphor 404c, a coating that emits fluorescence upon incidence of excitation light and transmits part of the excitation light (that is, semi-transmissive) is provided on the back side of the cover glass 404b. It may be applied to the whole. In this case, a part of the coating is removed by drawing a cross-shaped marking line 404d at the center of the light receiving section 404a, and this marking line 404d (that is, a thin line that does not emit excitation light) may be used as an index. . Further, as shown in FIG. 15, the entire surface of the back surface of the cover glass 404 b may be coated with a grid-shaped (square-shaped) phosphor 404 c. In this case, the coating of the indicator portion 404cb can be peeled off and used as an indicator. According to such a configuration, as long as the adjustment of the case 402 in the Z direction is completed, it becomes possible to observe the lattice-like fluorescence regardless of the position of the scanning path of the PSD 404. Positioning of the focus optical unit 204 and the case 402 becomes extremely easy.

  In the present embodiment, the phosphor 404c is formed inside the PSD 404 (the back side of the cover glass 404b (the light receiving surface 404a side)), but the present invention is not limited to this configuration. FIG. 16 is a diagram illustrating a modification of the calibration apparatus 400 according to the present embodiment. The calibration apparatus 400M according to the present modification is different from the calibration apparatus 400 according to the present embodiment in that the calibration apparatus 400M includes a beam splitter 403 and includes a phosphor 407 outside the PSD 404 instead of the phosphor 404c.

  The beam splitter 403 is disposed between the relay lens unit 406 and the PSD 404, transmits 50% of the excitation light from the relay lens unit 406 toward the PSD 404, and reflects 50%. The excitation light that has passed through the beam splitter 403 enters the PSD 404, and its scanning locus is detected as in this embodiment. On the other hand, the excitation light reflected by the beam splitter 403 enters the phosphor 407 and generates fluorescence. The surface of the phosphor 407 is coated with a fluorescent material having the same pattern as that of the frame-shaped portion 404ca and the indicator portion 404cb of this embodiment, and the surface of the phosphor 407 is optically equivalent to the light receiving surface 404a of the PSD 404. It is arranged in the position. Therefore, the fluorescence generated by the phosphor 407 follows the same path as the excitation light, enters the tip 202a of the optical fiber 202, and is displayed on the monitor 300 as an endoscopic image. As in the present embodiment, when the position of the case 402 is adjusted so that the fluorescence at the substantially central portion of the phosphor 407 is displayed on the monitor 300, the scanning locus of the excitation light is located at the substantially central portion of the light receiving surface 404a of the PSD 404. Moving. As described above, even when the phosphor 407 is arranged outside the PSD 404, the user can scan the scanning area A while viewing the endoscopic image (that is, the fluorescent image in the scanning area A) displayed on the monitor 300. , And can be adjusted to be within the light receiving surface 404 a of the PSD 404.

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, 400M Calibration device 402 Case 403 Beam splitter 404 PSD
404a Light-receiving surface 404b Cover glass 404c Phosphor 404ca Frame upper portion 404cb Indicator 404d Fluorescent reflection coating 405 PSD substrate 406 Relay lens unit 407 Phosphor 408 XYZ stage 410 Position adjustment knob 412 Calibration circuit

Claims (20)

An optical scanning device that periodically scans excitation light of a predetermined wavelength from a light source on a subject within a predetermined scanning range, and receives fluorescence generated from the subject excited by the excitation light emitted from the optical scanning device. And a calibration apparatus for a scanning confocal endoscope system for displaying a confocal image,
A relay lens that receives the excitation light emitted from the optical scanning device and expands the scanning range;
Light detection means for receiving excitation light emitted from the relay lens by a light receiving surface arranged perpendicular to the optical axis of the relay lens, and detecting a scanning locus on the light receiving surface of the received excitation light;
A fluorescent light emitter that is arranged at a position optically equivalent to the light receiving surface and emits fluorescence when excitation light emitted from the relay lens is incident;
Moving means for moving the relay lens and the light detection means relative to the optical scanning device;
Correction means for correcting the scanning parameter of the excitation light emitted from the optical scanning device so that the scanning locus detected by the light detection means becomes a reference scanning locus;
With
The relay lens is arranged so that a rear focal point of the relay lens substantially coincides with a center position of the light receiving surface;
The moving means, based on the fluorescence of the fluorescent light emitter displayed in the confocal image, the position of the front focal point of the relay lens substantially coincides with the condensing point of the excitation light emitted from the optical scanning device, A calibration apparatus, wherein the relay lens and the light detection means are moved so that a scanning range of excitation light emitted from the relay lens is within the light receiving surface. The fluorescent light emitter includes an indicator portion indicating a position equivalent to the center of the light receiving surface,
The moving means moves the relay lens and the light detecting means so that a center of a scanning range of excitation light emitted from the relay lens substantially coincides with a center of the light receiving surface. The calibration apparatus according to 1.   3. The index portion is a cross-shaped index formed by two straight lines that are orthogonal to the optical axis of the relay lens and are orthogonal to each other at a position equivalent to the center of the light receiving surface. The calibration device described in 1.   The calibration apparatus according to claim 3, wherein the cross-shaped index is formed by a solid line.   The calibration apparatus according to claim 3, wherein the cross-shaped index is formed by a broken line.   The calibration apparatus according to claim 2, wherein the index unit includes a plurality of indices having a predetermined shape discretely arranged in a plane equivalent to the light receiving surface.   The calibration apparatus according to claim 2, wherein the index unit includes a distance index indicating a distance from a center of the light receiving surface.   The distance indicator is a scale-like indicator formed so as to be orthogonal to the cross-shaped indicator according to the distance from the center of the light receiving surface. The calibration device according to claim 7, wherein one item is cited.   The calibration apparatus according to claim 7, wherein the distance index is an index having a different shape according to a distance from a center of the light receiving surface. The fluorescent light emitter includes a frame portion formed so as to surround the periphery of the light receiving surface at a position equivalent to the light receiving surface,
The said moving means moves the said relay lens and the said light detection means so that the scanning range of the excitation light radiate | emitted from the said relay lens may not cover the said frame part, Any one of Claim 1-9 The calibration apparatus according to claim 1.   The fluorescent light emitter covers the light receiving surface and the periphery of the light receiving surface at a position equivalent to the light receiving surface, and transmits a part of the excitation light incident from the relay lens. The calibration device described.   The calibration apparatus according to claim 11, wherein the fluorescent light emitter includes an indicator portion that does not emit fluorescence formed by two straight lines orthogonal to each other at a position equivalent to the center of the light receiving surface.   The calibration apparatus according to claim 11, wherein the fluorescent light emitter is formed in a grid shape. The light detection means includes a cover glass on the front surface of the light receiving surface,
The calibration device according to claim 1, wherein the fluorescent light emitter is coated on a surface of the cover glass that faces the light receiving surface.   The calibration apparatus according to claim 14, wherein a fluorescent reflection coating that reflects fluorescence generated by the fluorescent light emitter is formed on the fluorescent light emitter.   Located between the relay lens and the light detection means, the excitation light incident through the relay lens is divided and emitted to the light detection means and the fluorescent light emitter, and simultaneously emitted from the fluorescent light emitter. The calibration apparatus according to any one of claims 1 to 13, further comprising a beam splitter that reflects fluorescence toward the relay lens.   The scanning parameters include a first parameter for enlarging or reducing the scanning range of the scanning light, a second parameter for changing the shape of the scanning range of the scanning light, and a third parameter for changing the scanning speed of the scanning light. The calibration apparatus according to claim 1, comprising at least one of the following parameters.   2. A remap table creating unit that samples a scanning locus of the enlarged scanning light corrected by the correcting unit at a predetermined timing and assigns a two-dimensional raster coordinate to each sampling point. The calibration device according to claim 17.   The calibration device according to claim 1, wherein the relay lens, the light detection unit, and the fluorescent light emitter are accommodated in a single casing.   The calibration apparatus according to claim 19, wherein the casing shields at least the light detection unit from outside light.