JP2011089817A - Optical tomographic image acquisition device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire an accurate tomographic image in an optical tomographic image acquisition device for use in dentistry or the like. <P>SOLUTION: The optical tomographic image acquisition device includes a light source 20, a division unit 21 for dividing the light emitted from the light source, a probe 1 for irradiating an object to be measured 4 with one of the divided lights from a light input and output unit 2 and taking in the reflected light from the object to be measured as measuring light from the light input and output unit, a reference mirror 22 for correcting the route of the other light divided by the division unit 21, an interference part 23 for allowing the light corrected in route from the reference mirror 22 to interfere with the measuring light taken in by the probe 1 to form interference light and a tomographic image operation part 25 for operationally processing the interference light formed in the interference part 23 to form the tomographic image data of the object to be measured. The tomographic image operation part is provided with the light refraction member provided to the light input and output unit of the probe or a non-measuring light removing means 50 for removing the signal due to the back reflected light from a permeable cover body. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical tomographic image acquisition apparatus utilized for medical purposes, for example.

  Conventionally, the configuration of an optical tomographic image acquisition apparatus utilized for medical purposes has been as follows.

  That is, a light source, a dividing unit that divides the light emitted from the light source, and one of the divided lights is irradiated onto the measurement target from the light input / output unit, and reflected light from the measurement target is emitted from the light input / output unit. A probe that captures as measurement light, a reference mirror that corrects the path of the other light split by the splitting unit, a path-corrected light from the reference mirror, and a measurement light captured by the probe interfere with each other. An interference unit that generates light, and a tomographic image calculation unit that generates the tomographic image information to be measured by calculating the interference light generated by the interference unit (for example, this) The technique similar to is described in Patent Document 1 below).

JP-A-6-154228

  The problem in the conventional example is that an accurate optical tomographic image cannot be acquired.

  That is, in the above conventional optical tomographic image acquisition apparatus, in order to acquire tomographic image information of a measurement target, a probe that irradiates light toward the measurement target and captures reflected light from the measurement target as measurement light. However, a light refracting member such as a prism for changing the optical axis so that the probe can be easily irradiated on the object to be measured and a transparent cover body for improving the hygienic surface of the probe are used. It was the structure prepared for the entrance / exit.

  In this way, the light irradiation direction of the probe can be changed, so that the convenience of the probe is improved, and saliva etc. enters the probe by providing a transparent cover body at the light input / output portion. Therefore, the hygiene aspect of the probe can be improved, but the phenomenon that the tomographic image of the measurement object cannot be obtained accurately has occurred.

  The present inventor has been diligently examining the reason why such a tomographic image of the measurement target cannot be obtained accurately, and from a light refracting member such as a prism provided in the light path with respect to the measurement target, or a transparent cover body. It was found that the fact that a trace amount of light reflected backwards is mixed in the measurement light is the reason why the tomographic image of the measurement object cannot be obtained accurately.

  Therefore, an object of the present invention is to acquire an accurate tomographic image.

  In order to achieve this object, the present invention provides a light source, a dividing unit that divides the light emitted from the light source, and one of the divided lights into a photorefractive member or a transmissive cover body. A probe that irradiates the measurement target from the provided light input / output unit and takes reflected light from the measurement target as measurement light from the light input / output unit, and corrects the path of the other light divided by the division unit An interference unit that generates interference light by causing interference between the reference mirror, the path-corrected light from the reference mirror, and the measurement light captured by the probe, and processing the interference light generated by the interference unit A tomographic image calculation unit that generates tomographic image information to be measured, and the tomographic image calculation unit is provided with the light refraction member provided at the light input / output unit of the probe or a transmissive cover body. Signal component of back reflected light from The unmeasured light removing means for removing from the frequency component calculation result of the interference light is provided, thereby it is to achieve the intended purpose.

  As described above, the present invention provides a light source, a dividing unit that divides light emitted from the light source, and a light entering / exiting unit provided with a light refracting member or a transmissive cover for one of the divided lights. A probe that irradiates the measurement object from the light source and receives reflected light from the measurement object as measurement light from the light input / output unit, and a reference mirror that corrects the path of the other light divided by the division unit, An interference unit that generates interference light by causing interference between the path-corrected light from the reference mirror and the measurement light captured by the probe, and processing the interference light generated by the interference unit to perform measurement processing. A tomographic image calculation unit for generating tomographic image information, wherein the tomographic image calculation unit is a back-reflected light from the photorefractive member provided at the light input / output unit of the probe or a transparent cover body. Signal component due to interference light frequency component Since is provided with a non-measuring light removing means for removing from the calculation result, it is possible to obtain an accurate optical tomography.

  That is, in the optical tomographic image acquisition apparatus of the present invention, when irradiating the measurement target with light, it is reflected backward from a light refracting member such as a prism provided at the light input / output part of the probe with respect to the measurement target or a transparent cover body. Since the signal mixed in the measurement light is removed from the tomographic image information to be measured, an accurate optical tomographic image can be acquired.

The perspective view which shows the usage example of one Embodiment of this invention Perspective view Front view of the display The exploded perspective view The exploded perspective view The exploded perspective view of the principal part The exploded perspective view of the principal part The exploded perspective view of the principal part Exploded front view of the main part Its electrical block diagram Sectional view when using the main part Front view of the display Frequency spectrum diagram of the interference light Front view of the display Frequency spectrum diagram of the interference light

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  In FIG. 1, reference numeral 1 denotes a probe main body, and a light input / output part 2 is mounted in front of the probe main body 1 in a protruding state.

  As will be described in detail later, as shown in FIG. 1, the optical tomographic image acquisition apparatus according to the present embodiment inserts the light input / output unit 2 into the oral cavity 3 and displays the optical tomographic image of the tooth 4 in the X-axis direction. It is acquired continuously in the axial direction.

  Now, as shown in FIG. 2, the probe main body 1 has a cylindrical shape so that it can be held with one hand, and a control box 6 is connected to the rear end via a cable 5. In the cable 5, wiring for optical input / output and electrical signals are accommodated.

  Further, as shown in FIGS. 4 to 9, the probe main body 1 has a collimator lens 7 that makes the near-infrared light for measurement (1310 nanometers) parallel light. The outside light is scanned in the uniaxial direction by the optical scanning unit 8, subsequently moved in the direction orthogonal thereto, and then scanned in the uniaxial direction again, that is, in the same scanning state for image formation in the conventional CRT television. Scanned in state.

  Then, the scanned light is applied to the teeth 4 in FIG. 1 through the wavelength separation mirror 9 and the prism 10 as shown in FIGS. As is understood from the image of the display unit 12 shown in FIG. 3, this irradiation is scanned in the X-axis direction of the tooth 11, and the tomographic image at the time of scanning in the X-axis direction is the display unit 13 in the upper part of FIG. Is displayed.

  On the display unit 13, the caries 14 not found in the lower display unit 12 is displayed as a tomographic image. For example, it can be confirmed that the caries 14 that was only seen as a slight black spot on the surface of the tooth 11 has a large opening downward as in the display unit 13 when a tomographic image is taken. In some cases, dental caries will be treated immediately. That is, early treatment is possible.

  Subsequently, at the next moment, scanning in the X-axis direction is performed again with a slight movement in the Y-axis direction, and the image at this time is displayed on the display unit 13 again. Of course, even if the tomographic image is not immediately displayed on the display unit 13 every time scanning in the X-axis direction as described above, it can be confirmed later by manually operating the dentist while sending the images one by one.

  In order to form such an image, a light emitting element 15 for illumination is arranged below the wavelength separation mirror 9 as shown in FIGS. 6 and 7, and the light from the light emitting element 15 is transmitted to the wavelength separation mirror. 9, and is applied to the teeth 11 through the prism 10. By this irradiation, the light reflected from the teeth and incident on the prism 10 from the light input / output opening 10 a is reflected again by the prism 10, subsequently reflected by the wavelength separation mirror 9, and detected as an image by the camera 16. This is the image shown on the display unit 12 described above.

  In other words, the image 12 is used to display which tooth 11 is being tomographically acquired. The infrared image shown in FIGS. 4 and 6 is displayed while viewing the image on the display unit 12. A light scan is performed.

  In this way, the scanned infrared light travels straight through the wavelength separation mirror 9 and returns to the control box 6 via the collimator lens 7, where image processing is performed, and an image after this processing is displayed on the display unit 13 in FIG. Is displayed. That is, FIG. 3 shows the display unit 17 of the control box 6.

  Here, the image processing in the control box 6 will be described.

  The light source 18 in FIG. 10 is a wavelength swept light source, and the light emitted from the light source 18 is divided by the dividing unit 19 and a part thereof is supplied to the optical scanning unit 8 via the cable 5, and the above-described teeth 4 are described above. Scanning in the X-axis direction and the Y-axis direction is performed.

  The remaining light divided by the dividing unit 19 is reflected by the reference mirror 20 and supplied to the interference unit 21. In the interference unit 21, the light reflected by the reference 20 and the light returned through the optical scanning unit 8 and the cable 5 are caused to interfere with each other, converted into an electric signal by the light receiving unit 22, and processed for tomographic image calculation To the unit 23.

  The control unit 24 controls the observation image calculation unit 25 to display the observation image on the display unit 12 shown in FIG. 3 in real time. The tomographic image calculation unit 23 is controlled by the control unit 24 to display the tomographic image on the display unit 13 shown in FIG.

  The optical scanning unit 8 in this embodiment includes a first motor 27 that swings the galvano mirror 26 shown in FIGS. 4, 6, and 8 in a uniaxial direction (X direction in FIG. 6), and the first motor 27. And a second motor 28 that swings in the direction of the other axis perpendicular to the one axis (the Y-axis direction in FIG. 6). The first motor 27 and the second motor 28 are shown in FIG. Thus, they were arranged in a substantially parallel direction.

  Specifically, as shown in FIG. 6, the first motor 27 is held by the horizontal portion 30 of the L-shaped holder 29, and the vertical portion 31 of the L-shaped holder 29 is held by the second motor 28. It is connected to a drive shaft to be driven (32 in FIGS. 5 and 9). The drive shaft 32 is pivotally supported by a bearing 33 fixed to the probe body 1, and one end side thereof is fixed to the vertical portion 31 of the holder 29 described above, and the worm wheel 34 is fixed to the other end side.

  Further, the worm wheel 34 is engaged with the worm gear 35 of the second motor 28, whereby the first motor 27 can be swung via the holder 29 by the second motor 28. This swinging causes the galvanometer mirror 26 to swing, thereby enabling movement in the Y-axis direction of FIG.

  That is, the first motor 27 swings the galvanometer mirror 26 to scan in the X-axis direction of FIG. 6, and the second motor 28 swings the galvanometer mirror 26 together with the motor 27. , Scanning in the Y-axis direction can be performed.

  In the present embodiment, since the first and second motors 27 and 28 for causing the galvano mirror 26 to scan in the X-axis direction and the Y-axis direction are arranged in a substantially parallel state in this way, from FIG. As shown in FIG. 9, the probe main body 1 is miniaturized, so that the dentist can easily operate with one hand.

  As shown in FIGS. 8 and 9, a lead wire 36 for supplying power and a control signal is connected to the first motor 27, and a connection portion on one end side of the lead wire 36 is connected. The portion of the lead wire 36 up to the holding portion 37 to the probe body 1 is substantially S-shaped, so that the load when the first motor 27 swings is small, and the load is substantially the same when reciprocating. It is trying to become.

In the above configuration, the largest feature point in the present embodiment will be described below.
FIG. 11 is a view showing a cross-sectional structure when the light input / output part 2 of the probe main body 1 is inserted into the oral cavity. As described above, the light input / output part 2 is provided in front of the probe main body 1, the prism 10 as a light refracting member is provided at the tip thereof, and the protective cover 38 as a transparent cover body is provided with light. It is provided so as to cover the opening at the tip of the input / output part 2.

  As described above, light incident from the optical probe main body 1 side is refracted by the prism 10 that is a light refracting member, and is irradiated to the tooth 4 that is the measurement object through the protective cover 38 that is a transparent cover body. . The light irradiated on the teeth 4 is reflected and returned as measurement light from the protective cover 38 to the probe main body 1 side via the prism 10 again.

  The problem in this case is that when irradiating light on the tooth 4 to be measured, this light does not completely pass through the interface 39 of the prism 10 or the interface 40 of the protective cover, so that some of the light is behind. In other words, the reflected light 41 is mixed into the measurement light and returned to the probe body 1 side.

  Since the measurement light mixed with the reflected light 41 interferes with the reference light from the reference mirror 22 in the interference unit 23 to generate interference light, the reflected light 41 is mixed into the interference light. As a result, the optical tomographic image obtained from the interference light cannot display an accurate tomographic image of the measurement object as a result.

  Now, how the reflected light 41 affects the tomographic image will be specifically described.

  FIG. 12 shows an optical tomographic image of a tooth. A tooth tomographic image 43 is displayed on the display screen 42, and above this display screen 42, the influence of the reflected light 41 backward from the interface 39 of the prism 10 or the interface 40 of the protective cover described above. As shown, the interface line 44 is displayed.

  A diagram of the frequency spectrum of the interference light in the A line of the display screen 42 is shown in FIG.

  An optical tomographic image of the tooth to be measured can be obtained by analyzing the frequency spectrum of the interference light. As for the frequency spectrum of the interference light, it is possible to obtain information on a location close to the probe from a low frequency region. The tooth surface corresponds to the second peak 45 of the frequency spectrum of the interference light, and the spectrum corresponding to the tooth depth direction is obtained by analyzing a region having a higher frequency than the second peak 45. be able to.

  The interface line 44 described above corresponds to the first peak 46 of the frequency spectrum of the interference light. On the display screen 42, the upper display area including the interface line 44 is an area that is not necessary for the tomographic information of the tooth to be measured. That is, in order to obtain tooth tomographic information, the information on the spectrum of the interference light including the first peak 46 of the frequency spectrum of the interference light and the frequency lower than the frequency 47 of the first peak is removed. By analyzing and calculating this spectrum, an accurate tooth tomographic image can be obtained.

  Next, how to remove the interference light spectrum information in the frequency region lower than the first peak frequency 47 will be described.

  FIG. 14 shows a tomographic image obtained from the interference light in the state of the probe alone. FIG. 15 shows the frequency spectrum distribution of the interference light of the A line at this time.

  In this way, when the interference light is measured with the probe alone, only the interface line 44 is displayed. Therefore, even in the spectrum distribution of this interference light, the gain (magnitude) of the first peak 46 and the frequency 47 thereof are set. Can be measured. When the frequency 47 is measured in advance and the interference light to be measured is measured, the frequency spectrum information of the interference light in the region lower than the frequency 47 including the frequency 47 is obtained from the information of the frequency spectrum of the interference light. It is possible to obtain accurate tomographic image information of the measurement target by removing.

  As a method of measuring the interference light with the probe alone, for example, the measurement with the probe alone can be performed by measuring the interference light in a state where it is placed on the probe installation portion 48 provided on the upper surface of the control box 6 in FIG. It becomes possible.

  Next, another method for removing the interface line 44 will be described.

  First, with respect to the interference light spectrum obtained by measuring the measurement target, the spectrum peak is analyzed from the lower frequency side, and the spectrum having a peak of a predetermined size or more that appears on the lower frequency side than the predetermined frequency. It is possible to capture only the tomographic information of the measurement object by removing the component below this frequency including this frequency.

  In this case, it is necessary to adjust in advance in which frequency region the interface line 44 appears in the frequency spectrum region of the interference light. The method of measuring optical tomographic information in the embodiment of the present invention will be described with reference to FIG. 10 again. Light emitted from the light source 20 is divided into two by the dividing unit 21, one of which is optical up to the reference mirror 22. The light enters the interference section 23 via the path length, and the other is irradiated onto the measurement object 4 via the light input / output section of the probe described above, and the probe captures the reflected light of the measurement object 4 as measurement light. The interference unit 23 is entered. In the interference light generated by the interference unit 23, the optical path length X from the division unit 21 through the reference mirror 22 to the interference unit, the tip of the optical path from the division unit 21 to the light input / output unit 2 of the probe, That is, the difference from the optical path length Y to the interference portion via the interface 39 of the prism 10 or the interface 40 of the protective cover 38 appears as a spectrum of interference light. What is important here is that the optical path length X must be shorter than the optical path length Y. That is, the optical path length is set so that a point equal to the optical path length X is located on the rear side of the interface 39 of the prism 10 or the interface 40 of the protective cover 38 corresponding to the interface line 44. There must be.

  This setting method will be described with reference to FIG. 10. The control unit 26 analyzes the interference light of the probe alone with the FFT unit 49 provided in the tomographic image calculation unit 25, and as described above, in FIG. Setting can be made by correcting the position of the reference mirror 22 so that the frequency 47 of the first peak 46 of the frequency spectrum is equal to or lower than a predetermined frequency.

  Furthermore, in this state, the non-measurement light removing unit 50 can remove the frequency spectrum component equal to or lower than the frequency of the first peak 46, thereby generating accurate tomographic information of the measurement object 4.

  In this way, the optical path length X from the division unit to the interference unit via the reference mirror is equal to or less than the optical path length Y from the division unit to the interference unit via the light input / output unit of the probe. By designing and adjusting, the frequency 47 of the first peak 46 of the frequency spectrum of the interference light by the interface line 44 can be set to a predetermined frequency or lower.

  Further, the optical path length X from the dividing unit to the interference unit through the reference mirror is substantially equal to the optical path length Y from the dividing unit to the interference unit through the light input / output unit of the probe. By design and adjustment, the frequency 47 of the first peak 46 of the interference light frequency spectrum caused by the interface line 44 is substantially zero, so the first peak 46 is removed from the frequency spectrum. It becomes possible.

  As described above, adjustment of the optical path length and removal of a specific frequency spectrum also require adjustment at the time of production of the apparatus, but this is not sufficient. The reason is that even in the environment where the apparatus according to the embodiment of the present invention is used, the optical path length changes due to aging of the probe body, the mechanical shift, or the influence of the environment such as temperature, humidity, etc. The path length changes, so that it is necessary to make regular adjustments during use.

  For this reason, the adjustment means described above substantially requires calibration adjustment for each use not only at the time of product shipment but also in the use environment after product shipment.

  As described above, in the optical tomographic image acquisition apparatus according to the embodiment of the present invention, when irradiating light to the measurement target, a light refracting member such as a prism provided at the light input / output portion of the probe with respect to the measurement target, or transparency Since the signal reflected backward from the cover body and mixed into the measurement light is removed from the tomographic image information to be measured, an accurate optical tomographic image can be acquired.

  In addition, the use of a prism or a protective cover in the optical tomographic image acquisition apparatus makes it possible to change the light irradiation direction of the probe, thereby improving the convenience of the probe and also providing a transparent protective cover for the probe. By providing the light entrance / exit, saliva and the like can be prevented from entering the probe, so that the hygiene of the probe can be improved.

  As described above, the present invention provides a light source, a dividing unit that divides light emitted from the light source, and a light entering / exiting unit provided with a light refracting member or a transmissive cover for one of the divided lights. A probe that irradiates the measurement object from the light source and receives reflected light from the measurement object as measurement light from the light input / output unit, a reference mirror that corrects the path of the other light divided by the division unit, and the reference mirror An interference unit that generates interference light by causing interference between the path-corrected light from the probe and the measurement light captured by the probe, and a tomographic image of the measurement target by performing arithmetic processing on the interference light generated by the interference unit A tomographic image calculation unit that generates information, and the tomographic image calculation unit is a signal generated by back reflected light from the photorefractive member provided at the light input / output unit of the probe or a transparent cover body. Calculate the frequency component of interference light Since is provided with a non-measuring light removing means for removing from, it is possible to obtain an accurate optical tomography.

  That is, in the optical tomographic image acquisition apparatus of the present invention, when irradiating the measurement target with light, it is reflected backward from a light refracting member such as a prism provided at the light input / output part of the probe with respect to the measurement target or a transparent cover body. Since the signal mixed in the measurement light is removed from the tomographic image information to be measured, an accurate optical tomographic image can be acquired.

  Therefore, for example, it is expected to be widely used as a dental optical tomographic image acquisition apparatus.

DESCRIPTION OF SYMBOLS 1 Probe main body 2 Light entrance / exit part 3 Oral cavity 4 Teeth 5 Cable 6 Control box 7 Collimator lens 8 Optical scanning part 9 Wavelength separation mirror 10 Prism 11 Tooth 12 Display part 13 Display part 14 Caries 15 Light emitting element 16 Camera 17 Display part 18 Light source 19 Dividing part 20 Reference mirror 21 Interfering part 22 Light receiving part 23 Tomographic image computing part 24 Control part 25 Observation image computing part 26 Galvano mirror 27 Motor 28 Motor 29 Holder 30 Horizontal part 31 Vertical part 32 Drive shaft 33 Bearing 34 Warm wheel 35 Worm gear 36 Lead wire 37 Holding portion 38 Protective cover 39 Prism interface 40 Protective cover interface 41 Back reflected light 42 Display screen 43 Tomographic image of teeth 44 Interface line 45 Second peak 46 First peak 47 First peak 47 Frequency 48 Probe setting Part 49 FFT unit 50 unmeasured light removing means

Claims (4)

A light source, a dividing unit that divides the light emitted from the light source, and one of the divided lights are irradiated toward a measurement target from a light entering / exiting unit provided with a photorefractive member or a transmissive cover body. , A probe that takes reflected light from the measurement object as measurement light from the light input / output unit, a reference mirror that corrects the path of the other light divided by the dividing unit, and a path correction from the reference mirror An interference unit that generates interference light by causing interference between the light and the measurement light captured by the probe, and a tomographic image that generates the tomographic image information to be measured by calculating the interference light generated by the interference unit And a computing unit for
The tomographic image calculation unit removes the signal component due to the back reflected light from the light refraction member provided at the light input / output portion of the probe or the transparent cover body from the frequency component calculation result of the interference light. An optical tomographic image acquisition apparatus provided with light removing means. The optical tomographic image acquisition apparatus according to claim 1, wherein the non-measurement light removing unit removes a component of interference light having a predetermined frequency or less. The non-measurement light removing unit measures a frequency having a spectrum of a predetermined size or more in a region of a predetermined frequency or less from a calculation result of the frequency spectrum of the interference light in the tomographic image calculation unit, and this frequency The optical tomographic image acquisition apparatus according to claim 1 or 2, wherein the following components are removed. The optical path length from the dividing unit to the interference unit via the reference mirror is less than or equal to the optical path length from the dividing unit to the interference unit via the photorefractive member or the transmissive cover body. The optical tomographic image acquisition apparatus according to any one of claims 1 to 3, configured as described above.

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