Abstract:
A scanning endoscope device including two core portions that are provided parallel to each other and that radiate illuminating beams having optical characteristics different from each other toward a subject; a driving unit that two-dimensionally scans the two illuminating beams radiated from the core portions by causing vibration of distal-end portions of the core portions; a light receiving unit that receives return beams, returned from the subject, of the two illuminating beams; a light splitting unit that splits the return beams received by the light receiving unit according to the optical characteristics; two light detecting units that photoelectrically convert the two return beams split by the light splitting unit to output captured image signals; and an image generating unit that generates two images for two viewpoint based on the each captured image signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation of International Application PCT/JP2012/055186, with an international filing date of Mar. 1, 2012, which is hereby incorporated by reference herein in its entirety. This application claims the benefit of Japanese Patent Application No. 2011-080634, the content of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to scanning endoscope devices. 
       BACKGROUND ART 
       [0003]    Conventional scanning endoscope devices that obtain two images from different viewpoints (parallax images) by irradiating mutually displaced points on an observation target with two light beams while two-dimensionally scanning the light beams are known (e.g., see Patent Document 1). It is possible to stereoscopically view the observation target by using such parallax images. In the case of Patent Document 1, actuators for scanning light beams are provided, one for each light beam, at the distal-end portion of an inserted portion. 
       CITATION LIST 
     Patent Literature 
     {PTL 1} 
       [0004]    Specification of U.S. Patent Application Publication No. 2009/0137893 
       SUMMARY OF INVENTION 
     Solution to Problem 
       [0005]    The present invention provides a scanning endoscope device that obtains a parallax image, including a first core portion that radiates an illuminating light beam for a first viewpoint toward a subject, the illuminating light beam having a first optical characteristic; a second core portion that is provided parallel to the first core portion and that radiates an illuminating light beam for a second viewpoint toward the subject, the illuminating light beam having a second optical characteristic different from the first optical characteristic; a driving unit that two-dimensionally scans the illuminating light beam radiated from the first core portion and the illuminating light beam radiated from the second core portion by causing vibration of distal-end portions of the first core portion and the second core portion; a light receiving unit that receives return light beams, returned from the subject, of the illuminating light beam radiated from the first core portion and the illuminating light beam radiated from the second core portion; a light splitting unit that splits the return light beams received by the light receiving unit into a return light beam having the first optical characteristic and a return light beam having the second optical characteristic; a first light detecting unit that photoelectrically converts the return light beam split by the light splitting unit and having the first optical characteristic to output a first captured image signal for the first viewpoint; a second light detecting unit that photoelectrically converts the return light beam split by the light splitting unit and having the second optical characteristic to output a second captured image signal for the second viewpoint; and an image generating unit that generates a first image for the first viewpoint based on the first captured image signal output from the first light detecting unit and that generates a second image for the second viewpoint based on the second captured image signal output from the second light detecting unit. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0006]    {FIG.  1 } 
           [0007]      FIG. 1  is an overall construction diagram of a scanning endoscope device according to an embodiment of the present invention. 
           [0008]    {FIG.  2 } 
           [0009]      FIG. 2  is an enlarged view of the distal-end portions of light-emitting fibers in  FIG. 1 . 
           [0010]    {FIG.  3 } 
           [0011]      FIG. 3  is an illustration showing the distal-end face of an inserted portion in  FIG. 1 . 
           [0012]    {FIG.  4 } 
           [0013]      FIG. 4  is a diagram showing two scanning areas where illuminating light beams are scanned by the scanning endoscope device in  FIG. 1 . 
           [0014]    {FIG.  5 } 
           [0015]      FIG. 5  is an illustration showing a modification of the light-emitting fibers in  FIG. 1 . 
           [0016]    {FIG.  6 } 
           [0017]      FIG. 6  is an illustration showing a construction in which GRIN lenses are provided at the distal-end faces of the light-emitting fibers in  FIG. 2 . 
           [0018]    {FIG.  7 } 
           [0019]      FIG. 7  is an illustration showing a construction in which ball lenses are provided at the distal-end faces of the light-emitting fibers in  FIG. 2 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0020]    A scanning endoscope device  1  according to an embodiment of the present invention will be described below with reference to the drawings. 
         [0021]    The scanning endoscope device  1  according to this embodiment obtains parallax images that enable stereoscopic viewing by the parallel method. As shown in  FIG. 1 , the scanning endoscope device  1  includes an inserted portion  5  having light-emitting fibers (optical fiber component)  2  that emit illuminating light beams L 1  and L 2 , light-receiving fibers  3 , and an actuator (driving unit)  4  that causes vibration of the distal-end portions of the light-emitting fibers  2 ; an illumination unit  6  that supplies the illuminating light beams L 1  and L 2  to the light-emitting fibers  2 ; a driving unit  7  that drives the actuator  4 ; a detection unit (detecting unit)  8  that performs photoelectric conversion of return light beams of the illuminating light beams L 1  and L 2  received by the light-receiving fibers  3 ; an image generation unit  9  that generates parallax images based on signals from the detection unit  8 ; and a control unit  10  that controls the operation of the illumination unit  6  and the driving unit  7  and that outputs the parallax images generated by the image generation unit  9  to a monitor  14 . 
         [0022]    The light-emitting fibers  2  and the light-receiving fibers  3  are disposed along the lengthwise direction inside the inserted portion  5 . At the distal end of the light-emitting fibers  2 , an illumination optical system  11  is provided. 
         [0023]    As shown in  FIG. 2 , the light-emitting fibers  2  include two optical fibers  21  and  22  that are joined together at least at their distal-end portions. The optical fibers  21  and  22  are single-mode fibers having cores (core portions)  21   a  and  22   a,  respectively. A first illuminating light beam L 1  emitted from one core  21   a  and a second illuminating light beam L 2  emitted from the other core  22   a  are condensed by the illumination optical system  11  and irradiate an observation surface A. 
         [0024]    Here, as will be described later, the wavelength of the first illuminating light beam L 1  and the wavelength of the second illuminating light beam L 2  mutually differ. Therefore, because of aberrations that arise when these illuminating light beams L 1  and L 2  pass through the illumination optical system  11 , the illuminating light beams L 1  and L 2  irradiate points on the observation surface A that are displaced in a direction crossing the optical axes. 
         [0025]    At this time, preferably, the displacement d between the two illuminating light beams L 1  and L 2  is, for example, greater than or equal to about 80 μm and less than or equal to about 500 μm. Considering the diameter of each of the optical fibers  21  and  22 , it is difficult to make the displacement d between the irradiated points less than 80 μm. On the other hand, a displacement d between the irradiated points greater than 500 μm is undesirable since the diameter of the inserted portion  5  becomes large. The displacement d between the irradiated points can also be designed by adjusting the distance between the two cores  21   a  and  22   a,  the emitting directions of the illuminating light beams L 1  and L 2  from the individual cores  21   a  and  22   a,  etc. 
         [0026]    The light-receiving fibers  3  commonly receive return light beams of the two illuminating light beams L 1  and L 2  with light receiving faces (light receiving unit)  31  formed of the distal-end faces thereof and guide the received return light beams to the detection unit  8 . Here, as shown in  FIG. 3 , multiple ( 12  in the example shown in the figure) light-receiving fibers  3  are provided, and the light receiving faces  31  are arranged to surround the illumination optical system  11  in the circumferential direction on the distal-end face of the inserted portion  5 . This serves to increase the intensity of the return light received from the observation surface A. 
         [0027]    The actuator  4  is, for example, an electromagnetic or piezoelectric actuator. When driving voltages (described later) are applied from the driving unit  7 , the actuator  4  causes the distal-end portions of the light-emitting fibers  2  to vibrate in the directions of two axes (X direction and Y direction) crossing the lengthwise direction of the light-emitting fibers  2 . Thus, the two illuminating light beams L 1  and L 2  are simultaneously scanned two-dimensionally on the observation surface A. There is no particular limitation about the scanning method, and spiral scanning, raster scanning, etc. can be used. 
         [0028]    Here, since the distal-end portions of the two optical fibers  21  and  22  are joined together, the scanning trajectories of the two illuminating light beams L 1  and L 2  have the same shape, as shown in  FIG. 4 . Furthermore, scanning areas S 1  and S 2  (areas scanned by spiral scanning in the example shown in the figure) on the observation surface A scanned with the two illuminating light beams L 1  and L 2  are displaced by the displacement d between the points irradiated with the two illuminating light beams L 1  and L 2 . 
         [0029]    The illumination unit  6  is constructed to make the first illuminating light beam L 1  having a first wavelength incident on one core  21   a  and to make the second illuminating light beam L 2  having a second wavelength, which differs from the first wavelength, incident on the other core  22   a.  The first illuminating light beam L 1  and the second illuminating light beam L 2  are single-wavelength continuous-wave light. The first wavelength and the second wavelength are, for example, 532 nm and 440 nm. The illumination unit  6  is constructed of, for example, two light sources that individually emit the first illuminating light beam L 1  and the second illuminating light beam L 2 . As the light sources, single-wavelength solid-state lasers, which have superior light guiding efficiency, are preferable. 
         [0030]    The driving unit  7  includes a signal generator  71  that generates driving signals for driving the actuator  4  in the form of digital signals, D/A converters  72   a  and  72   b  that convert the driving signals generated by the signal generator  71  into analog signals, and a signal amplifier  73  that amplifies outputs of the D/A converters  72   a  and  72   b.    
         [0031]    The signal generator  71  generates two driving signals for vibrating the light-emitting fibers  2  in the X direction and Y direction and inputs the two driving signals to the separate D/A converters  72   a  and  72   b.  The signal amplifier  73  amplifies the analog signals generated by the D/A converters  72   a  and  72   b,  i.e., driving voltages, to an amplitude suitable for driving the actuator  4  and outputs the amplified driving voltages to the actuator  4 . 
         [0032]    The detecting unit  8  includes a wavelength splitter (wavelength splitting mechanism)  81  that splits return light beams guided by the individual light-receiving fibers  3  on the basis of their wavelengths and two light detectors  82   a  and  82   b  that detect the individual return light beams split by the wavelength splitter  81  and that performs photoelectric conversion. 
         [0033]    The wavelength splitter (wavelength splitting unit)  81  extracts a return light beam having the first wavelength and a return light beam having the second wavelength among the input return light beams and outputs these return light beams to the separate light detectors  82   a  and  82   b.    
         [0034]    The light detectors (light detecting unit)  82   a  and  82   b  are, for example, photodiodes or photomultiplier tubes. The light detectors  82   a  and  82   b  output photocurrents having magnitudes corresponding to the intensities of the detected return light beams to A/D converters  91   a  and  91   b , respectively. 
         [0035]    The image generation unit  9  includes two A/D converters  91   a  and  91   b  that convert the photocurrents output from the individual light detectors  82   a  and  82   b  into digital signals and a parallax-image generator  92  that generates two-dimensional images from the digital signals generated by the individual A/D converters  91   a  and  91   b.    
         [0036]    The parallax-image generator  92  generates two two-dimensional images based on the digital signals received from the individual A/D converters  91   a  and  91   b  and information about the scanning positions of the illuminating light beams L 1  and L 2  (described later) received from the control unit  10 . Here, the two two-dimensional images are an image generated from the return light beam from the scanning area S 1  scanned with the first illuminating light beam L 1  and an image generated from the return light beam from the scanning area S 2  scanned with the second illuminating light beam L 2 . That is, the two two-dimensional images are images whose viewpoints are shifted in parallel by an amount corresponding to the displacement d between the points irradiated with the two illuminating light beams L 1  and L 2 . It is possible to construct a parallax image from these two two-dimensional images. 
         [0037]    The control unit  10  outputs specification signals giving the specifications of the driving signals, e.g., the frequency, amplitude, etc., to the signal generator  71  and outputs information about the specification signals, i.e., information including the scanning positions of the illuminating light beams L 1  and L 2 , to the parallax-image generator  92 . 
         [0038]    Furthermore, the control unit  10  reconstructs an image suitable for stereoscopic observation from the two two-dimensional images received from the parallax-image generator  92  and displays the reconstructed image on the monitor  14 . This enables an operator to stereoscopically observe an image of the observation surface A generated by the scanning endoscope device  1 . 
         [0039]    In this case, according to this embodiment, even though the construction is such that parallax images are obtained by using the two illuminating light beams L 1  and L 2 , the single actuator  4  suffices to scan the two illuminating light beams L 1  and L 2 , so that an advantage is afforded in that the diameter of the inserted portion  5  can be made small. Furthermore, since images of the observation surface A are obtained by using the illuminating light beams L 1  and L 2  having different wavelengths, it becomes possible to perform simultaneous observation using light beams in different wavelength ranges. For example, by modifying the first illuminating light beam L 1  to an excitation light beam for a fluorescent pigment (e.g., a near-infrared light beam), modifying the second excitation light beam L 2  to a white light beam in which light beams from three solid-state lasers for RGB are combined, and suitably modifying the wavelengths of the return light beams split by the wavelength splitter  81 , it becomes possible to simultaneously observe a fluorescence image and a white-light image. 
         [0040]    Although the illuminating light beams L 1  and L 2  radiated from the individual cores  21   a  and  22   a  have mutually different wavelengths in this embodiment, alternatively, the illuminating light beams L 1  and L 2  may have mutually different polarization directions. In this case, the illumination unit  6  includes, for example, two polarizers that extract light beams having different polarization directions and that output the light beams to the individual cores  21   a  and  22   a . Furthermore, a polarized-light splitter (not shown, polarized-light splitting mechanism) that extracts light beams having the individual polarization directions is provided between the observation surface A and the light receiving faces  31 . 
         [0041]    Also with this construction, it is possible to separately detect return light beams from the individual scanning areas S 1  and S 2  and to separately generate images of the individual scanning areas S 1  and S 2 . Furthermore, it becomes possible to use light beams having the same wavelength as the first illuminating light beam L 1  and the second illuminating light beam L 2 . 
         [0042]    Furthermore, although the light-emitting fibers  2  include the two optical fibers  21  and  22  having a single core in this embodiment, alternatively, the light-emitting fiber  2  may consist of a single optical fiber  23  having two cores  23   a  and  23   b,  as shown in  FIG. 5 . 
         [0043]    Also with this construction, it is possible to obtain parallax images by two-dimensionally scanning two illuminating light beams irradiating points that are displaced in a direction crossing the optical axes, simultaneously by means of the single actuator  4 . 
         [0044]    Furthermore, in this embodiment, optical components that condense the illuminating light beams L 1  and L 2  emitted from the individual cores  21   a  and  22   a  into collimated light beams or into smaller spot diameters may be joined at the distal-end faces of the two optical fibers  21  and  22 . As the optical components, for example, GRIN (gradient index) lenses  12 , shown in  FIG. 6 , or ball lenses  13 , shown in  FIG. 7 , are used. This serves to improve the resolution of the parallax images. In the case where optical components are provided as described above, the illumination optical system  11  may be omitted. 
         [0045]    Furthermore, although continuous light beams are used as the illuminating light beams L 1  and L 2  in this embodiment, alternatively, pulsed light beams may be used. 
         [0046]    With this construction, since the cumulative irradiation periods of the observation surface A with the illuminating light beams L 1  and L 2  become shorter, the effects exerted on the observation surface A by the illuminating light beams L 1  and L 2  can be alleviated. For example, in the case of fluorescence observation, fading of the fluorescent pigment can be prevented. Furthermore, in the case where the observation surface A is irradiated with the first illuminating light beam L 1  and the second illuminating light beam L 2  in a time-division multiplexing, it is possible to perform time-resolved measurement of the behavior of biological molecules, etc. on the observation surface A. 
         [0047]    In the case where pulsed light beams are used as the illuminating light beams L 1  and L 2 , the illumination unit  6  may be constructed to make the two illuminating light beams L 1  and L 2  incident on the individual cores  21   a  and  22   a  at pulse timings shifted from each other, and the detection unit  8  may be constructed to detect return light beams in synchronization with the pulse timings. In this construction, the wavelengths of the illuminating light beams L 1  and L 2  may be either the same or different. The latter case is suitable for fluorescence imaging using two different fluorescent pigments. 
         [0048]    Furthermore, although the light-emitting fibers  2  include the two cores  21   a  and  22   a  in this embodiment, alternatively, the light-emitting fibers  2  may include three or more cores. For example, even in the case where the distal-end portions of three or more optical fibers having a single core are joined together, the single actuator  4  suffices to scan illuminating light beams from all the cores. Therefore, it is possible to obtain images of the observation surface A by using three or more illuminating light beams while making the diameter of the inserted portion  5  small. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  Scanning endoscope device 
           2  Light-emitting fibers 
           3  Light-receiving fibers 
           4  Actuator (driving unit) 
           5  Inserted portion 
           6  Illumination unit (illuminating unit) 
           7  Driving unit 
           8  Detection unit (detecting unit) 
           9  Image generation unit (image generating unit) 
           10  Control unit 
           11  Illumination optical system 
           12  GRIN lenses (optical components) 
           13  Ball lenses (optical components) 
           14  Monitor 
           21 ,  22 ,  23  Optical fibers (optical fiber component) 
           21   a,    22   a,    23   a,    23   b  Cores (core portions) 
           31  Light receiving faces (light receiving unit) 
           71  Signal generator 
           72   a,    72   b  D/A converters 
           73  Signal amplifier 
           81  Wavelength splitter (wavelength splitting mechanism) 
           82   a,    82   b  Light detectors 
           91   a,    91   b  A/D converters 
           92  Parallax-image generator 
         A Observation surface 
         L 1  First illuminating light beam 
         L 2  Second illuminating light beam