JP2012152244A - Optical fiber scanning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute calibration even when an optical fiber scanning device is inserted in the body or the like.SOLUTION: An optical fiber 12 is inserted in the scope of an endoscopic apparatus. The fiber tip part 12A of the optical fiber 12 is displaced along a definite vortical route. A built-in chart member 20 is attached to the inside of the scope so as to be arranged in front of the fiber tip part 12A. In a case looking from a forward side, the built-in chart member 20 is equipped with the annular outside part 21 provided so as to surround the optical fiber 12 and the cross center part 22 arranged at the position coinciding with or near to the optical fiber 12. A part of the light emitted from the fiber tip part 12A displaced along the definite route is applied to the built-in chart member 20 and the return light thereof is incident on the optical fiber 12. The calibration is executed on the basis of the image of the return light from the built-in chart member 20.

Description

  The present invention relates to an optical fiber scanning device that scans an observation object while displacing an optical fiber.

  2. Description of the Related Art An optical fiber scanning device that scans an observation object while irradiating illumination light while displacing the optical fiber tip is known. In this device, the fiber tip is displaced, for example, by an actuator attached near the tip. The drive of the actuator is controlled so that the displacement of the fiber tip becomes, for example, a perfect circular spiral. However, even if the actuator is driven as set, the fiber tip may not be displaced along the set path due to various factors such as attachment error and environmental temperature.

  For this reason, in an optical fiber scanning device, calibration is generally performed before use, for example, so that the optical fiber is displaced in a perfect spiral shape. Conventionally, calibration is performed by photographing a chart and correcting the driving of the actuator in accordance with the shape of the photographed chart image (see, for example, Patent Document 1).

US Patent Application Publication No. 2008/0165360

  However, in the conventional calibration method, it is necessary to prepare a dedicated chart and manually place it in front of the fiber, so that the workability is not good. Further, when the fiber scanning apparatus is applied to an endoscope, for example, there is a problem that calibration cannot be performed during use because it is inserted into the body.

  Accordingly, an object of the present invention is to provide an optical fiber scanning apparatus that can perform calibration even when a dedicated chart is not prepared and is used in the body or the like.

  An optical fiber scanning device according to the present invention includes a scope unit, an optical fiber that is inserted into the scope unit and emits irradiation light for irradiating an observation object from the tip, and a drive that displaces the tip of the optical fiber. Means and an image generating means for generating an observation image of one frame by returning light from the observation object when the tip of the optical fiber is displaced along a certain path to scan the observation object A chart member attached to the scope unit so as to be irradiated with the irradiation light from the optical fiber disposed in front of the optical fiber and displaced in a part of the fixed path, and a return from the chart member And a calibration means for calibrating the optical fiber scanning device based on the light.

  For example, when the tip of the optical fiber displaced along a certain path is disposed within a certain region, the observation object is irradiated with the irradiation light, and the obtained return light from the observation object causes the one frame of the above-mentioned one frame. An observation image is generated. At this time, it is preferable that at least a part of the chart member is irradiated with irradiation light when the tip of the fiber is displaced outside a certain region. The chart member has, for example, an outer portion provided so as to surround the optical fiber when viewed from the front side. Moreover, it is preferable that an outer side part is cyclic | annular. Further, it is preferable that the chart member includes a central portion that is arranged at a position that coincides with or is close to the optical fiber when not driven by the driving means when viewed from the front side.

  For example, while the tip of the optical fiber is displaced along the above-described fixed path, the return light of the irradiation light is sampled at a predetermined sampling rate to generate a pixel signal. Here, at least a part of the fixed path has relatively dense sampling points for sampling the pixel signal as compared with other parts. It is preferable that at least a part of the chart member is irradiated with irradiation light from an optical fiber disposed in a portion where sampling points are relatively dense.

  The pixel signal generated from the return light of the chart member is preferably separated from the pixel signal generated from the return light of the observation object. In this case, for example, the return light from the chart member has a higher intensity than the return light from the observation object. A pixel signal having a relatively large output value is used as a pixel signal generated from the return light of the chart member, and a pixel signal having a relatively small output value is used as a pixel signal generated from the return light of the observation object. It is preferable to separate.

  The return light from the chart member may have a wavelength different from that of the return light from the observation object. At this time, the return light from the chart member is preferably separated from the return light from the observation object by the optical member. The observation image is generated by the return light from the observation object received by the first light receiving element, and the calibration is performed by the return light from the chart member received by the second light receiving element. Are preferred.

  The return light from the chart member is preferably incident from the distal end of the optical fiber and emitted from the proximal end. The optical fiber scanning device may allow the return light from the observation object to enter the optical fiber, but may include an image fiber into which the return light from the observation object is incident separately from the optical fiber. . The image generation means generates an observation image by light guided from the optical fiber or light guided by the image fiber.

  For example, the chart member reflects irradiation light and uses the reflected light as return light, or is excited by the irradiation light and emits fluorescence as return light. The tip of the optical fiber is displaced along, for example, a spiral path. The calibration means preferably performs calibration by correcting the displacement of the optical fiber.

  The optical fiber scanning device preferably generates a chart image based on return light from the chart member, and performs calibration when the chart image does not match the reference chart image.

  The optical fiber scanning device preferably includes a memory that stores data relating to a reference chart image obtained by return light from the chart member when the tip of the optical fiber is displaced along the standard path. In this case, the optical fiber scanning device compares the data related to the reference chart image with the data related to the chart image obtained from the return light of the chart member so that the shape of the chart image matches the shape of the reference chart image. Perform calibration.

  A second optical fiber scanning device according to the present invention includes a scope unit, an optical fiber that is inserted into the scope unit and emits irradiation light for irradiating an observation object from the tip, and a tip of the optical fiber. An image for generating an observation image of one frame by return light from the observation object when the driving means for displacing and the tip of the optical fiber are displaced along a certain path to scan the observation object A chart member attached to the scope unit so as to be irradiated with the irradiation light from the optical fiber disposed in front of the optical fiber and displaced in a part of the fixed path; And chart data generating means for acquiring image data relating to the chart member based on the return light from the head.

  In the present invention, calibration can be performed without preparing a dedicated chart and even when the optical fiber scanning device is inserted into the body or the like.

It is a block diagram showing the whole endoscope apparatus in a 1st embodiment. It is typical sectional drawing which showed the inside of the scope front-end | tip part. It is the graph which showed the waveform of the drive signal for driving an actuator. It is the schematic diagram which showed the displacement path | route of the fiber front-end | tip part. It is a graph which shows the relationship between the intensity | strength of fluorescence received with the fluorescence light receiving element, and time passage in one frame period. It is a schematic diagram which shows a mode that a cross center part is scanned. It is a graph which shows the relationship between the intensity | strength of the fluorescence received with the fluorescence light receiving element, and time passage immediately after a scanning period start. It is a flowchart which shows an observation image generation routine. It is a schematic diagram which shows a mode when a fluorescence image and a fluorescence image are isolate | separated into the observation image and the built-in chart image. It is a flowchart which shows a reference | standard chart acquisition routine. It is a top view which shows an external chart. It is a schematic diagram which shows the process in which a reference | standard chart image is obtained. It is a schematic diagram which shows the process in which the reference | standard chart image is obtained when distortion is seen in an external chart image. It is the fluorescence image for reference | standard chart acquisition obtained when a built-in chart member is an ellipse, and a reference | standard chart image. It is the fluorescence image for reference | standard chart acquisition obtained when a built-in chart member is eccentric, and a reference | standard chart image. It is the block diagram which showed the whole endoscope apparatus in 2nd Embodiment. It is the block diagram which showed the whole endoscope apparatus in 3rd Embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
In the embodiment described below, the optical fiber scanning device according to the present invention is applied to an endoscope device.

  As shown in FIG. 1, the endoscope apparatus includes a scope 10 and a processor 30, and an optical fiber 12 is inserted into the scope 10. The optical fiber 12 has its distal end (fiber distal end portion 12A) disposed at the distal end of the scope 10 (scope distal end portion 10A) and a proximal end portion 12B connected to the processor 30. The optical fiber 12 is a single-mode scanning optical fiber.

  The processor 30 is provided with a condenser lens 31, a laser light source 32, a laser driving unit 33, and a filter 34. The laser light source 32 is driven by the laser driving unit 33 and emits a light beam of excitation light. The excitation light is composed of light of a specific wavelength such as ultraviolet light, for example, and excites the observation object OB to emit fluorescence from the observation object OB. Fluorescence is light having a longer wavelength than the excitation light, and has a wavelength different from that of the excitation light. The filter 34 is a dichroic mirror that reflects excitation light and transmits fluorescence.

  The excitation light emitted from the laser light source 32 is reflected by the filter 34 and is incident on the proximal end portion 12 </ b> B of the optical fiber 12 through the condenser lens 31. Excitation light is transmitted through the optical fiber 12 and emitted from the core end face of the fiber tip 12A. Excitation light emitted from the core end face is irradiated to the observation object OB through the confocal optical system 14 and the cover lens 15. In the present embodiment, since confocal observation is performed, the observation object OB is observed in contact with the cover lens 15.

  A built-in chart member 20 is provided inside the scope distal end portion 10A. The excitation light emitted from the fiber tip portion 12A is also applied to the built-in chart member 20. The built-in chart member 20 is made of a phosphor, and is excited to emit fluorescence when irradiated with excitation light. The built-in chart member 20 is formed of a material having high conversion efficiency from excitation light to fluorescence.

  An actuator 13 for vibrating and displacing the fiber tip 12A is attached in the vicinity of the tip 12A of the optical fiber 12. The actuator 13 is driven by a fiber drive unit 41 provided in the processor 30. The fiber drive unit 41 drives the actuator 13 based on the drive signal having the signal waveform generated by the waveform generation processing unit 42. As will be described in detail below, the fiber tip portion 12A is displaced along a spiral path (a constant path) by the actuator 13 in one frame period.

  Fluorescence (returned light) emitted from the observation object OB and the built-in chart member 20 is incident on the fiber distal end portion 12A and transmitted to the proximal end portion 12B of the optical fiber 12. The fluorescence is emitted from the base end portion 12 </ b> B, collected by the condenser lens 31, transmitted through the filter 34, and received by the fluorescence light receiving element 35 inside the processor 30. The fluorescence light receiving element 35 is, for example, a photomultiplier tube (PMT). The fluorescence light receiving element 35 generates a pixel signal corresponding to the intensity of fluorescence received in a predetermined minute period. The generation of the pixel signal is repeated in one frame period.

  The pixel signal obtained by the fluorescence light receiving element 35 is amplified by the amplifier 36, converted to a digital pixel signal by the A / D converter 37, and sent to the image generation unit 38. In the image generation unit 38, the pixel position of each pixel signal is specified by mapping the pixel signal sequentially transmitted during one frame period and the scanning position of the excitation light. The pixel signals are arranged so as to generate an image of one frame, and are temporarily stored in the image memory 40 as a fluorescence image FI (see FIG. 9). The scanning position of the excitation light is estimated based on the drive signal output from the fiber drive unit 41.

  As shown in FIG. 9, the fluorescence image FI includes an observation image OI obtained by fluorescence from the observation object OB and a built-in chart image CI obtained by fluorescence from the built-in chart member 20. As will be described later, the observation image OI and the built-in chart image CI are separated, and the observation image OI is output to the monitor 50 via the encoder 39. The built-in chart image CI is used as an image for calibration.

  The processor 30 is provided with a timing controller 45 and a controller 46. The timing controller 45 outputs a synchronization signal to the laser drive unit 33 and the fiber drive unit 41 to synchronize the vibration of the fiber tip portion 12A and the light emission timing. The timing controller 45 outputs a clock pulse signal (drive signal) to the fluorescence light receiving element 35 and controls the generation timing of the pixel signal in the fluorescence light receiving element 35. The controller 46 is a circuit for controlling the driving of the entire processor 30 and outputs a driving signal to the timing controller 45 and the like.

  Next, the structure of the scope tip will be described in more detail with reference to FIG. The scope distal end portion 10A includes a cylindrical housing 18 that houses each member therein. In the scope distal end portion 10A, a confocal optical system 14 held on the inner peripheral surface of the housing 18 is disposed in front of the fiber distal end portion 12A. A cover lens 15 is arranged in front of the confocal optical system 14 so as to close the end of the housing 18.

  The core end surface of the fiber distal end portion 12A is brought into a confocal relationship with the observation object OB arranged so as to be in contact with the cover lens 15 by the confocal optical system 14. That is, the excitation light emitted from the core end surface is focused on the observation object OB, and the fluorescence emitted therefrom is focused on the core end surface of the fiber tip portion 12A.

  The actuator 13 is a tube-type actuator using a piezoelectric element, and resonates the fiber tip portion 12A two-dimensionally. The actuator 13 is provided with a piezoelectric element for performing resonance in the X direction and resonance in the Y direction. The X direction and the Y direction are directions perpendicular to the axial direction (Z direction) of the optical fiber 12 when the optical fiber 12 is not bent, and are perpendicular to each other. The actuator 13 vibrates the fiber tip 12A in a predetermined resonance mode along the X direction and the Y direction.

  The built-in chart member 20 is disposed in front of the fiber tip portion 12 </ b> A so that light from the optical fiber 12 is irradiated inside the housing 18. The built-in chart member 20 includes an annular outer ring portion 21 and a cross-shaped cross center portion 22. The annular outer portion 21 is fixed to the inner peripheral surface of the housing 18 and is provided so as to surround the optical fiber 12 when viewed from the front side. As a result, the annular outer portion 21 is not provided on the optical path of the excitation light for observing the subject, and does not hinder the observation of the subject by the excitation light.

  The cross-shaped central portion 22 is attached to the center of the back surface of the cover lens 15 and, when viewed from the front side, is located at or close to the optical fiber 12 that is not bent (that is, when not being driven by the actuator 13). Placed in position. As a result, the cross central portion 22 is provided on the optical path of the excitation light for observing the subject. However, as will be described later, the cruciform central portion 22 is provided corresponding to the portion where the sampling points S are dense. Will not be disturbed. In addition, the cross center part 22 is attached on the lens 15 by vapor deposition, for example.

  The excitation light received by the outer annular portion 21 is light emitted from the fiber tip portion 12A having a large amplitude width and inclined with respect to the Z direction. For this reason, the light receiving surface 21A of the annular outer portion 21 facing the fiber tip portion 12A is inclined with respect to the Z direction, so that the light emitted from the fiber tip portion 12A is substantially perpendicular to the light receiving surface 21A. Is received.

  A light shielding member 24 is attached to the outer ring portion 21. The light shielding member 24 is provided so as to cover an exposed portion of the annular outer portion 21 other than the light receiving surface 21A and surround an optical path toward the light receiving surface 21A. Thereby, it is prevented that the fluorescence emitted from the annular outer portion 21 is scattered.

  FIG. 3 shows a signal waveform of a drive signal for driving the piezoelectric element of the actuator. FIG. 3 shows a signal waveform of a drive signal input to the piezoelectric element for X direction resonance in one frame period. In one frame period, first, a scanning period for driving the fiber tip in a spiral shape is started. In the scanning period, a drive signal having a waveform as represented by the following formula (1) is input to the piezoelectric element.

  Note that the waveform of the drive signal represented by Expression (1) is an ideal standard waveform, and is usually corrected by calibration or the like which will be described later. The waveform of the drive signal input to the Y-direction resonance piezoelectric element is the same as that in FIG. 3, but the standard waveform of the signal waveform in the scanning period is expressed by Equation (2).

x = tsin (wt) (1)
y = tcos (wt) (2)
In Expressions (1) and (2), x and y are positions in the X and Y directions, t is time, and w is frequency.

  As is clear from these equations (1) and (2), the fiber tip is oscillated around the reference position SP during the scanning period, and the amplitude width is gradually increased from the state at the reference position SP in the X and Y directions. By enlarging to a certain value, it is displaced along a certain spiral path CP (see FIG. 4). The path CP is ideally a substantially circular spiral, but the path CP may be distorted due to an actuator mounting error, an environmental temperature, or the like, for example, an elliptical spiral. The reference position SP is usually a position where the fiber tip is disposed when the optical fiber is not bent. Further, the number of turns of the spiral is about 10 in the examples of FIGS. 3 and 4, but is usually more.

  As apparent from FIGS. 2 and 4, the fiber tip portion 12 </ b> A has a small amplitude width, and when it is disposed inside the constant region CR, the excitation light is observed through the confocal optical system 14 and the cover lens 15. The object OB is irradiated. During this time, the observation object OB is scanned in a substantially circular (or elliptical) spiral shape, and the image generation unit 38 (see FIG. 1) generates a substantially circular (or elliptical) observation image OI (see FIG. 9). Is done. The fixed region CR is a region that is substantially circular (or elliptical) when viewed from the front centered on the reference position SP.

  On the other hand, when the amplitude width in the X direction and the Y direction becomes relatively large and the fiber tip portion 12A is disposed outside the fixed region CR, the excitation light travels from the fiber tip portion 12A toward the observation object OB. And enters the annular outer portion 21 of the built-in chart member 20. Further, when the fiber tip portion 12A is at or near the reference position SP that is the approximate center of the constant region CR, the excitation light does not irradiate the observation object OB, and the cross center portion 22 of the built-in chart member 20 Is incident on.

  That is, the excitation light emitted from the fiber tip portion 12 </ b> A arranged in a part of the spiral constant path CP is irradiated to the built-in chart member 20. Therefore, in the scanning period, an image is also formed by fluorescence from the built-in chart member 20, and the built-in chart image CI (see FIG. 9) that is an image of the built-in chart member 20 is included in the fluorescence image FI.

  In the scanning period, pixel signals are sampled (generated) at a constant sampling rate. For this reason, the sampling points S that are positions for sampling the pixel signals in the fixed path CP are dense while the amplitude width in the X direction and Y direction of the fiber tip portion 12A is small, but gradually become sparse as they become larger. It will become. That is, the cross center portion 22 is irradiated with excitation light from the fiber tip portion 12A disposed on the path CP where the sampling points S are relatively dense.

  As shown in FIG. 3, the drive signal shifts from the scanning period to the braking period when the amplitude width of the fiber tip 12A reaches a predetermined magnitude. During the braking period, the fiber tip portion 12A is stopped from vibrating by the braking operation and returned to the reference position SP.

  FIG. 5 is a graph showing the relationship between the output voltage (intensity) of fluorescence received by the fluorescence light receiving element and the passage of time in one frame period. In the scanning period, the fluorescence from the observation object OB and the fluorescence from the built-in chart member 20 are received. Here, the fluorescence from the observation object OB has a relatively weak intensity. On the other hand, since the built-in chart member 20 has high light conversion efficiency as described above, the fluorescence emitted from the built-in chart member 20 is constant and the emission intensity is sufficiently larger than the fluorescence from the observation object OB. .

  Therefore, as shown in FIG. 5, immediately after the start of the scanning period or in the latter half of the scanning period, the light from the optical fiber is irradiated onto the built-in chart member, and the intensity of the pixel signal increases. However, since the light from the optical fiber is scanned in a spiral shape, the built-in chart member (cross central portion 22) scanned immediately after the start of the scanning period has a cross shape. As shown in FIG. 6, the scanning of the built-in chart member and the scanning of the observation object are repeated. Accordingly, the intensity of the pixel signal is similarly repeated as shown in FIG.

  The pixel signal obtained at each sample timing can be determined as the pixel signal of the built-in chart image CI (see FIG. 9) if the intensity is large, while the observation image OI (see FIG. 9) if the intensity is relatively small. ) Pixel signal. As is apparent from FIG. 5, the fluorescence light receiving element 35 generates a pixel signal even during the braking period, but the pixel signal is not used for image formation.

  Next, an observation image generation routine will be described with reference to FIG. The observation image generation routine is a routine for inserting the scope into the body and generating an observation image. In this routine, for the sake of simplification of explanation, an example in which steps S100 to S105 proceed in time series will be described. However, these steps need not proceed in time series, for example, steps S100 and S101 are performed. You may proceed at the same time. Although a case where calibration is performed every time an image of one frame is generated will be described, the calibration may be performed every time an image of several frames is generated, or is performed every predetermined time. Also good.

  In this routine, first, in step S100, pixel signals are sampled during the scanning period, and a fluorescence image FI (see FIG. 9) for one frame is generated. At this time, in the initial state, the fiber tip portion 12A is driven by the drive signal having the reference correction waveform acquired in step S204 as will be described later. On the other hand, after being calibrated in step S105, it is driven by a drive signal having a signal waveform generated by the calibration. However, in the initial state, it may be driven by the drive signal having the standard waveform shown by the equations (1) and (2). Note that, as described above, the observation image OI and the built-in chart image CI are reflected in the fluorescent image FI.

  Next, in step S101, as shown in FIG. 9, the fluorescence image FI is separated into an observation image OI and a built-in chart image CI. Specifically, it is determined whether or not the output value of each pixel signal of the fluorescence image FI is greater than a threshold value. As described with reference to FIG. 5, the pixel signal whose output value is greater than or equal to the threshold value is the pixel signal of the built-in chart image CI, and the pixel signal whose output value is smaller than the threshold value is the pixel of the observation image OI. Signal.

  As shown in FIG. 9, the built-in chart image CI includes a ring image DI that shows the outer ring portion 21 and a center image EI that shows the cross center portion 22. On the other hand, the observation image OI is an image obtained by photographing the observation object OB. However, since the built-in chart image CI is removed from the fluorescent image FI, the center of the observation image OI is a pixel-missing portion where the pixel signal is missing. It becomes MI.

  In step S102, the pixel signal of the pixel missing portion MI in the observation image OI is generated from the pixel signals of the peripheral pixels by pixel interpolation. As described above, since the center of the observation image OI corresponds to the portion where the sampling points S (see FIG. 4) are dense, even if the pixel signal is generated by pixel interpolation, the image quality is hardly deteriorated. Then, the observation image OI obtained by interpolation of the pixel signal of the pixel missing portion MI is output to the monitor 50 in step S103.

  In step S104, the built-in chart image CI is matched with a reference chart image stored in advance in the ROM in the controller 46. Here, the reference chart image is a built-in chart image generated when the displacement path of the fiber tip portion 12A follows the standard path which is an appropriate path by a reference chart acquisition routine described later. That is, the reference chart image is a true representation of the shape of the built-in chart member 20 without distortion.

  If it is determined as a result of the matching in step S104 that the built-in chart image CI matches the reference chart image, it is assumed that the displacement path of the fiber tip portion 12A in the scanning period follows an appropriate path, step S100. Return to. That is, image generation for the next frame is started in step S100 without being calibrated.

  On the other hand, if it is determined in step S104 that the built-in chart image CI does not match the reference chart image, the process proceeds to step S105, and calibration is performed. That is, the signal waveform of the drive signal is corrected so that the shape of the built-in chart image CI obtained in step S101 matches the shape of the reference chart image. After calibration, the process returns to step S100 to generate an image of the next frame.

  In the present embodiment, the matching in step S104 is performed, for example, assuming that the binarized built-in chart image CI and the annular image DI of the reference chart image are ellipses or circles. Then, for example, the determination is made based on whether parameters such as the major axis length, minor axis length and inclination of the annular image DI, and the position of the annular image DI with respect to the central image EI substantially match each other. The calibration performed in step S105 is performed by adjusting the amplitude, phase, x, y intercept, and the like of the signal waveform so that the difference between these parameters is eliminated. However, these matching and calibration are examples, and are not limited to these, and can be performed by other known methods.

  Next, a reference chart acquisition routine for obtaining a reference chart image will be described with reference to FIG. Note that this routine is performed at the time of regular maintenance before product shipment or after shipment.

  Before this routine is started, first, a chart (for example, the external chart 51) on which, for example, the alphabet “A” is made of paper as shown in FIG. 11 is prepared. Then, in a state where the external chart 51 is placed in front of the scope distal end 10A as the observation object OB, for example, a predetermined switch of the processor is input, and this routine is started.

  In this routine, first, in step S200, the fiber tip portion 12A is driven for one frame period, and a one-frame fluorescent image is generated. At this time, the fiber tip portion 12A is driven by the drive signal having the standard waveform shown in the equations (1) and (2) in the initial state. On the other hand, after the waveform of the drive signal is corrected in step S203, the drive signal having the corrected waveform is driven.

  The fluorescent image obtained in step S200 is a reference chart composed of an image of the external chart 51 (external chart image GI) placed in front of the scope tip and an image of the internal chart member 20 (internal chart image CI). It is the fluorescence image SI for acquisition (refer FIG. 12).

  In step S201, the reference chart acquisition fluorescent image SI is separated into the external chart image GI and the built-in chart image CI in the same manner as in step S101. That is, when the output value of the pixel signal is larger than the threshold value, the pixel signal of the built-in chart image CI is set as the pixel signal of the external chart image GI when the output value is equal to or less than the threshold value, and the reference chart acquisition fluorescent image SI is separated.

  In step S202, it is determined whether the external chart image GI is distorted. Whether or not the external chart image GI is distorted is determined based on whether or not the shape of the external chart image GI matches the shape of the reference external chart image HI as shown in FIG. If it is determined that they match, the process proceeds to step S204. If it is determined that they do not match, the process proceeds to step S203.

  Whether or not the external chart image GI matches the reference external chart image HI depends on, for example, whether the alphabets “A” in the binarized external chart image GI and the reference external chart image HI match. To be judged. Whether the alphabets “A” match each other is determined by known matching. However, when the pixel missing portion MI formed by the cross center portion 22 overlaps the alphabet “A”, the pixel signal of the pixel missing portion MI is also generated by pixel interpolation in this routine.

  The reference external chart image HI is an image with no distortion of the external chart 51 stored in advance in the ROM of the controller 46. Therefore, as shown in FIG. 12, when the shape of the external chart image GI matches the shape of the reference external chart image HI, the external chart image GI is not distorted. That is, the fiber tip portion 12A is displaced along an appropriate path (standard path) that does not cause distortion in the observed image. Therefore, the built-in chart image CI obtained from the reference chart acquisition fluorescent image SI in step S201 is also generated when the fiber tip 12A is displaced along an appropriate standard path, and the shape of the built-in chart member 20 is Is truly expressed without distortion.

  Therefore, in step S204, the built-in chart image CI obtained in step S201 is stored in the ROM as a reference chart image. Further, the signal waveform of the drive signal of the fiber tip portion 12A when the built-in chart image CI is generated is stored in the ROM as a reference correction waveform, and this routine ends. The reference chart image and the reference correction waveform are used in the image forming routine as described above.

  On the other hand, when the shape of the external chart image GI is distorted as shown in FIG. 13 and does not match the shape of the reference external chart image HI, the fiber tip 12A is not displaced along an appropriate reference path. . Therefore, in step S203, the waveform of the drive signal at the fiber tip is corrected, and the process returns to step S200. Then, steps S200 to S203 are repeated until the external chart image GI matches the reference external chart image HI.

  The correction of the waveform of the drive signal is performed by, for example, the amplitude, phase, and x, y intercept of the waveform so that the difference in aspect ratio, inclination, etc. between the binarized external chart image GI and the reference external chart image HI is eliminated. (Offset) is adjusted.

  Note that the example of FIG. 12 described above is an example in which the actual built-in chart member 20 is attached without error at the scope distal end portion 10A and exhibits a perfect circle. Therefore, the annular image of the reference chart image is a perfect circle.

  On the other hand, the example shown in FIG. 14 is an example of the reference chart image when the annular outer portion 21 of the actual built-in chart member 20 is not a perfect circle but an ellipse. In the example of FIG. 14, in the reference chart image, the shape of the annular image DI becomes an ellipse according to the actual shape of the built-in chart member 20. The example of FIG. 15 is an example of a reference chart image when the annular outer portion 21 of the built-in chart member 20 is formed in a perfect circle but is eccentric with respect to the cross center portion 22. In the example of FIG. 15, in the reference chart image, the ring image DI is decentered with respect to the center image EI.

  As described above, in the present embodiment, since the built-in chart member 20 is provided at the scope distal end portion 10A, the observation object OB is observed even when the scope 10 is inserted into the body. However, calibration can be performed.

  Further, the built-in chart member 20 is provided in the outer part of the optical path of the light emitted from the optical fiber 12 and in the central part where the sampling points are dense among the parts used for subject observation and the part used for subject observation. . Therefore, the subject observation is hardly hindered by the calibration. Furthermore, since the built-in chart member 20 includes the annular outer portion 21 and the cross center portion 22, it is possible to perform calibration in consideration of the relative positional relationship on the image. Therefore, for example, it becomes easy to prevent the fiber tip portion 12A from being eccentric and vibrating.

  In the present embodiment, the reference chart image representing the true shape of the built-in chart member 20 is acquired in the reference chart acquisition routine. Therefore, even if the built-in chart member 20 attached to the scope tip 10A is distorted or eccentric, calibration can be performed appropriately.

FIG. 16 is a block diagram showing an outline of an endoscope apparatus according to the second embodiment of the present invention.
In the first embodiment, the built-in chart member is made of a phosphor, but the built-in chart member 70 in the present embodiment is made of a reflector made of metal or the like. Hereinafter, the difference between the second embodiment and the first embodiment will be described. In addition, the same code | symbol is attached | subjected about the member same as 1st Embodiment.

  In the present embodiment, the processor 30 is provided with filters 74A and 74B instead of the filter 34. The filters 74A and 74B are half mirrors that transmit part of the incident light and reflect the rest. Further, an excitation light receiving element 75 is provided as a light receiving element in addition to the fluorescence light receiving element 35, and a fluorescence cut filter 79A and an excitation light cut filter 79B are provided in front of the excitation light receiving element 75 and the fluorescence light receiving element 35, respectively. Provided. The excitation light receiving element 75 is, for example, a photodiode (PD). The fluorescence cut filter 79A and the excitation light cut filter 79B are filters that cut light of a specific wavelength and transmit light of other wavelengths.

  Part of the excitation light emitted from the laser light source 32 passes through the filters 74A and 74B, is condensed by the condenser lens 31, and is incident on the proximal end portion 12B of the optical fiber 12. Excitation light passes through the inside of the optical fiber 12 and is irradiated to the observation object OB and the built-in chart member 70 as in the first embodiment.

  In the present embodiment, since the built-in chart member 70 is a reflector, the excitation light incident on the built-in chart member 70 is reflected by the built-in chart member 70 and enters the optical fiber 12. On the other hand, the return light from the observation object OB is fluorescent as in the first embodiment. Therefore, excitation light and fluorescence are emitted from the base end portion 12 </ b> B of the optical fiber 12.

  A part of the excitation light and fluorescence emitted from the base end part 12B is reflected by the filter 74A and partly transmitted. The excitation light and fluorescence reflected by the filter 74A are cut by the fluorescence cut filter 79A, and only the excitation light is received by the excitation light receiving element 75. The excitation light and fluorescence transmitted through the filter 74A are partially reflected by the filter 74B, and the excitation light is cut by the excitation light cut filter 79B, and only the fluorescence is received by the fluorescence light receiving element 35. That is, in the present embodiment, the return light (fluorescence) from the observation object and the return light (excitation light) from the built-in chart member are used to have different wavelengths, so that optical members such as a half mirror and a cut filter are used. Are received by different light receiving elements.

As in the first embodiment, the fluorescence light receiving element 35 generates a pixel signal corresponding to the intensity of fluorescence received in a predetermined minute period. Similarly, the excitation light receiving element 75 generates a pixel signal corresponding to the intensity of the excitation light received in a predetermined minute period. The generation of the pixel signal is repeated in one frame period in any light receiving element.

  The pixel signal obtained by the fluorescence light receiving element 35 is sent as a digital pixel signal to the image generation unit 38 as in the first embodiment, and the image generation unit 38 generates a fluorescence image for one frame from the pixel signal. can get. However, in the present embodiment, since the built-in chart member 70 does not emit fluorescence, the fluorescence image is composed only of the observation image OI (see FIG. 9) obtained by fluorescence from the observation object OB. The observation image OI is temporarily stored in the image memory 40 and then output to the monitor 50 via the encoder 39.

  The pixel signal obtained by the excitation light receiving element 75 is amplified by the amplifier 76, converted to a digital pixel signal by the A / D converter 77, and sent to the image generation unit 38. Similarly, an excitation light image for one frame is obtained from the pixel signal. The excitation light image is a built-in chart image CI (see FIG. 9) formed by reflected light from the built-in chart member 70. The built-in chart image CI is stored in the image memory 40 and used as an image for calibration.

  Note that the observation image generation routine and the reference chart acquisition routine in this embodiment are substantially the same as those in the first embodiment except that steps S101 and S201 are omitted, and thus detailed description thereof is omitted. .

  As described above, in the present embodiment, since the reflector is used as the built-in chart member, calibration can be performed without separating the fluorescent image into two images by image processing.

FIG. 17 is a block diagram showing an outline of an endoscope apparatus according to the third embodiment of the present invention.
In the first embodiment, the endoscope apparatus performs confocal observation with excitation light, but in the present embodiment, the endoscope apparatus normally observes the observation object OB with white light. Therefore, the observation object OB is observed separately from the cover lens 15. Hereinafter, a difference between the third embodiment and the first embodiment will be described. In addition, the same code | symbol is attached | subjected about the member same as 1st Embodiment.

  In the present embodiment, an illumination optical system 94 is disposed in front of the optical fiber 12 instead of the confocal optical system 14. In addition to the optical fiber 12, an optical fiber (hereinafter referred to as an image fiber) 92 that transmits reflected light from the observation object OB is inserted inside the scope 10. The distal end of the image fiber 92 is branched, and is disposed around the illumination optical system 94 and the cover lens 15, and its proximal end is connected to the processor 30.

  Further, the processor 30 is provided with laser light sources 82R, 82G, and 82B that respectively emit red, green, and blue light as laser light sources, and these are driven by laser drivers 83R, 83G, and 83B. In the present embodiment, white light is emitted toward the observation object OB by simultaneously emitting red, green, and blue light. The blue light emitted from the laser light source 82B is excitation light having a wavelength that can excite the built-in chart member 20.

  Inside the processor 30, a filter 84R, a filter 84G, and a filter 84B are disposed on an optical path of light emitted from the laser light sources 82R, 82G, and 82B. The filter 84R, the filter 84G, and the filter 84B are filters that reflect red, green, and blue light and transmit other light, respectively.

  The red, green, and blue light emitted from the laser light sources 82R, 82G, and 82B is reflected by the filter 84R, the filter 84G, and the filter 84B to form a single light beam, and is then converted into white light by the condenser lens 31. The light is condensed on the base end portion 12 </ b> B of the optical fiber 12. White light is transmitted through the optical fiber 12 to the fiber tip 12A.

  The white light is emitted from the fiber tip portion 12A, passes through the illumination optical system 94 and the cover lens 15, and is irradiated onto the observation object OB. In the present embodiment, the fiber tip portion 12A is driven in the same manner as in the first embodiment. Therefore, the white light from the fiber tip portion 12A is observed in the scanning period in the same manner as in the first embodiment. In addition to OB, the built-in chart member 20 is also irradiated.

  The white light applied to the observation object OB is reflected by the observation object OB, enters the image fiber 92 as reflected light, and is guided to the base end of the image fiber 92. The reflected light exits from the base end of the image fiber 92, is separated into red, green, and blue light by the optical lens 85 and the half mirror group 86, and enters the light receivers 87R, 87G, and 87B, respectively. The light receivers 87R, 87G, and 87B convert red, green, and blue light into R, G, and B pixel signals corresponding to their intensities, respectively.

  The R, G, and B pixel signals are converted into digital pixel signals by the A / D converters 89R, 89G, and 89B and sent to the image generation unit 38. The image generation unit 38 obtains a normal observation image of one frame from the R, G, and B digital pixel signals that are sequentially sent, and the normal observation image is temporarily stored in the image memory 40. Note that the normal observation image has a pixel missing portion as in the observation image of the first embodiment, but the pixel signal in the pixel missing portion is generated by pixel interpolation. The normal observation image stored in the image memory 40 is output to the monitor 50 via the encoder 39.

  On the other hand, in this embodiment, since the blue light emitted from the laser light source 82B is excitation light, the built-in chart member 20 is excited and emits fluorescence when irradiated with the light emitted from the fiber tip portion 12A. . The fluorescence emitted from the built-in chart member 20 is guided to the proximal end portion 12B of the optical fiber 12 through the optical fiber 12 as in the first embodiment. The fluorescence from the built-in chart member 20 passes through the condenser lens 31 and the filters 84R, 84G, and 84B and is received by the fluorescence light receiving element 35. In the fluorescence light receiving element 35, a pixel signal corresponding to the intensity of the fluorescence is generated as in the first embodiment.

  The pixel signal obtained by the fluorescence light receiving element 35 is sent as a digital pixel signal to the image generation unit 38 as in the first embodiment, and the image generation unit 38 obtains a fluorescence image for one frame. In the present embodiment, the fluorescence image for one frame is generated only by the return light from the built-in chart member 20, and consists of only the built-in chart image CI (see FIG. 9). The built-in chart image CI is stored in the image memory 40 and used as an image for calibration.

  Note that the observation image generation routine and the reference chart acquisition routine in this embodiment are substantially the same as those in the first embodiment except that steps S101 and S201 are omitted, and thus detailed description thereof is omitted. .

  As described above, even when normal observation is performed with white light or the like, calibration can be performed using the built-in chart image CI obtained by the built-in chart member 20.

  In the present embodiment, the built-in chart member may be formed of a reflector as in the second embodiment. The reflector may be a reflector that reflects all the light of R, G, and B, but may be a material that is coated with paint or the like and reflects at least one of R, G, and B. . In this case, in order to branch the optical path of the reflected light from the optical path of the laser light source, for example, a half mirror is provided between the condenser lens 31 and the filter 84R, and the light reflected by the half mirror is received. The light receiving element is provided.

  Further, in the present embodiment, the blue light emitted from the laser light source 82B is used as the excitation light, but a laser light source for excitation light for emitting excitation light composed of ultraviolet rays is used separately from the laser light source 82B. May be.

  The excitation light from the laser light source for excitation light may be combined with white light and emitted from the fiber tip 12A, but may be emitted at a different timing from the white light. In this case, for example, a switch for starting the calibration may be provided in the processor or the like, and when the switch is input, the excitation light may be emitted instead of the white light.

  With such a configuration, when a switch is input, the observation image OI is not generated, and only the built-in chart image CI is generated and calibration is performed. On the other hand, when a normal observation image is generated, the built-in chart image CI is not created, and calibration is not performed. That is, subject observation and calibration are performed separately. In each of the above embodiments, subject observation and calibration may be performed separately.

  In each of the above embodiments, in the reference chart acquisition routine, the image data of the reference chart image composed of a large number of pixel signals is stored in the ROM. However, the image data may be stored in the ROM in other formats. . For example, a parameter for representing the shape of the reference chart image may be stored in the ROM as data of the reference chart image.

  As the parameter, for example, the distortion / deviation of the actual annular image DI with respect to the ideal image when the annular image DI is a perfect circle centered on the center image EI is expressed as an affine transformation coefficient. It is. In this case, in step S104, the built-in chart image CI may be similarly represented as an affine transformation coefficient, and the coefficient may be compared with the coefficient of the reference chart image to perform matching between the images.

  When the built-in chart member can be molded and attached with a small error, the reference chart acquisition routine may be omitted, and image data related to the reference chart image may be stored in advance in a ROM or the like.

  When the reference chart acquisition routine is omitted, the calibration may be performed assuming that the outer ring portion 21 is a perfect circle. Specifically, when the annular outer portion 21 is a perfect circle and the optical fiber is displaced in a circular spiral along an appropriate path, the return light from the annular outer portion 21 is as shown in FIG. It becomes constant with high strength over a certain period (t1 to t2). On the other hand, when the optical fiber does not follow an appropriate path and is displaced, for example, in an elliptical spiral, there is a period in which the output value becomes weak in a certain period (t1 to t2). Therefore, for example, it may be determined whether or not the optical fiber path is appropriate by detecting whether or not there is a period during which the output value becomes weak during the certain period.

  Further, in each embodiment, the position where the built-in chart member is attached is not limited to the inner peripheral surface of the housing 18 and the back surface of the cover lens 15, and may be attached to other positions such as the front surface of the cover lens 15. Further, in the cover lens 15 coated with the antireflection coating, it is possible to make a part of the cover lens 15 not to be coated with the antireflection coating and to make the portion a reflector.

  In the above description, an example in which the tip portion of the optical fiber is scanned in a spiral shape has been described. However, the present invention describes an optical fiber in which the tip portion of the optical fiber is scanned by a different method such as a raster method. You may apply to a scanning apparatus.

DESCRIPTION OF SYMBOLS 10 Scope 10A Scope tip part 12 Optical fiber 12A Fiber tip part 13 Actuator 20 Built-in chart member 21 Circular outer part 22 Cross center part 30 Processor 38 Image generation part 42 Waveform generation process part CR Fixed area | region CI Chart image FI Fluorescence image OI Observation Image CP Fixed route

Claims (19)

A scope section;
An optical fiber that is inserted into the scope portion and emits irradiation light for irradiating the observation object from the tip;
Driving means for displacing the tip of the optical fiber;
Image generating means for generating an observation image of one frame by returning light from the observation object when the tip of the optical fiber is displaced along a certain path to scan the observation object; ,
A chart member attached to the scope unit so as to be irradiated with irradiation light from an optical fiber disposed in front of the optical fiber and displaced to a part of the fixed path;
An optical fiber scanning device comprising: calibration means for calibrating the optical fiber scanning device based on return light from the chart member. When the tip of the optical fiber displaced along the certain path is displaced within a certain area, the irradiation light is irradiated on the observation object, and the obtained return light from the observation object An observation image of one frame is generated,
The optical fiber scanning device according to claim 1, wherein at least a part of the chart member is irradiated with the irradiation light when the tip is displaced outside the certain region.   The optical fiber scanning device according to claim 1, wherein the chart member has an outer portion provided so as to surround the optical fiber when viewed from the front side.   The optical fiber scanning device according to claim 3, wherein the outer portion is annular.   4. The optical fiber according to claim 3, wherein the chart member includes a central portion that is disposed at a position that coincides with or is close to the optical fiber when not driven by the driving unit when viewed from the front side. Scanning device. While the tip of the optical fiber is displaced along the fixed path, the return light of the irradiation light is sampled at a predetermined sampling rate to generate a pixel signal,
At least a part of the fixed path has a relatively dense sampling point for sampling the pixel signal compared to other parts,
The optical fiber scanning device according to claim 1, wherein at least a part of the chart member is irradiated with irradiation light from an optical fiber disposed in a portion where the sampling points are relatively dense.   The optical fiber scanning device according to claim 1, wherein a pixel signal generated from the return light of the chart member is separated from a pixel signal generated from the return light of the observation object. The return light from the chart member is higher in intensity than the return light from the observation object,
A pixel signal having a relatively large output value is a pixel signal generated from the return light of the chart member, and a pixel signal having a relatively small output value is a pixel signal generated from the return light of the observation object. The optical fiber scanning device according to claim 7, wherein the optical fiber scanning device is separated.   2. The optical fiber scanning device according to claim 1, wherein the return light from the chart member has a wavelength different from that of the return light from the observation object. Return light from the chart member is separated from return light from the observation object by an optical member,
The observation image is generated by return light from the observation object received by the first light receiving element,
The optical fiber scanning device according to claim 9, wherein the calibration is performed by return light from the chart member received by a second light receiving element.   2. The optical fiber scanning device according to claim 1, wherein the return light from the chart member is incident from a distal end of the optical fiber and is emitted from a proximal end.   The optical fiber scanning device according to claim 11, wherein the return light from the observation object is incident from a distal end of the optical fiber and is emitted from a proximal end. A return light from the observation object is provided with an image fiber that is incident from the tip,
The optical fiber scanning device according to claim 1, wherein the image generation unit generates the observation image by light guided to the image fiber.   The optical fiber scanning device according to claim 1, wherein the chart member reflects the irradiation light and uses the reflected light as return light, or is excited by the irradiation light and emits fluorescence as return light.   The optical fiber scanning device according to claim 1, wherein the tip of the optical fiber is displaced along a spiral path.   The optical fiber scanning apparatus according to claim 1, wherein a chart image is generated based on return light from the chart member, and the calibration is performed when the chart image does not coincide with a reference chart image. A memory for storing data relating to a reference chart image obtained by return light from the chart member when the tip of the optical fiber is displaced along a standard path;
The data relating to the reference chart image and the data relating to the chart image obtained from the return light of the chart member are compared, and calibration is performed so that the shape of the chart image matches the shape of the reference chart image The optical fiber scanning device according to claim 1.   The optical fiber scanning apparatus according to claim 1, wherein the calibration unit performs the calibration by correcting a displacement of the optical fiber. A scope section;
An optical fiber that is inserted into the scope portion and emits irradiation light for irradiating the observation object from the tip;
Driving means for displacing the tip of the optical fiber;
Image generating means for generating an observation image of one frame by returning light from the observation object when the tip of the optical fiber is displaced along a certain path to scan the observation object; ,
A chart member attached to the scope unit so as to be irradiated with irradiation light from an optical fiber disposed in front of the optical fiber and displaced to a part of the fixed path;
An optical fiber scanning device comprising: chart data generation means for acquiring image data relating to the chart member based on return light from the chart member.

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