JP2011139774A - Optical tomographic image acquisition device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display an accurate tomographic image as for an optical tomographic image acquisition device for dental use etc. <P>SOLUTION: An interference light generated in an interference section 21 is subjected to FFT operation processing by an operation part 23 for tomographic images to generate tomographic image information of a measuring object, in addition, a display control part 50 is provided with an interface detection part 52 that analyzes the tomographic image information to detect an interface position. The interface position is controlled to display in the always fixed display position with respect to a display screen to prevent the movement of the display position due to bending of a cable material 5, thereby displaying the tomographic image accurately. <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 the first light divided by the dividing unit are irradiated from the light input / output unit toward the measurement target, and the reflected light from the measurement target A probe that takes in as measurement reflected light from the light input / output part, and guides the first light divided by the dividing part to the probe, and guides the measurement reflected light taken in by the probe. A cable material, a reference mirror that performs path length correction of the second light divided by the dividing unit, a reference light from the reference mirror, and a measurement reflected light guided by the cable material are caused to interfere with each other. An interference unit that generates interference light, a tomographic image calculation unit that calculates the tomographic image information to be measured by processing the interference light generated by the interference unit, and tomographic image information from the tomographic image calculation unit And a display control unit for displaying Which was.

  Among such conventional techniques, there has been provided a means for fixing a probe in order to prevent fluctuation of interference light due to disturbance to the apparatus (for example, a technique similar to this is described in Patent Document 1 below). Have been).

JP 2008-142443 A

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

  That is, in the conventional optical tomographic image acquisition apparatus, in order to acquire tomographic image information of a measurement object, the measurement obtained from the probe guided by the reference light from the reference mirror and the bendable cable material The reflected light is caused to interfere with each other to generate interference light, and the interference light generated by the interference unit is processed.

  In this way, since the cable material connected to the probe can be bent freely, the user can easily adjust the position of the probe, so that the operability of the probe can be improved, but the tomographic image of the measurement target is accurate. The phenomenon that can not be displayed on.

  The present inventor has intensively studied the reason why such a tomographic image of the measurement target cannot be accurately displayed, so that the cable material connected to the probe can be freely bent. The path length of the measurement light guided to the cable material and the measurement reflection light may change, and the interference light using the measurement reflection light whose path length has changed may be calculated and the result displayed as it is. As a conclusion, we found that the tomographic image of the measurement object cannot be displayed accurately.

  In view of the above, an object of the present invention is to display 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 the first light divided by the dividing unit as a photorefractive member or a transparent material. A probe that irradiates the measurement target from the light input / output unit provided with the cover body, and takes in the reflected light from the measurement target as measurement reflected light from the light input / output unit, and the first divided by the dividing unit A bendable cable member that guides light to the probe and guides measurement reflected light taken by the probe; a reference mirror that corrects the path length of the second light divided by the divider; An interference unit that generates interference light by causing interference between the reference light from the reference mirror and the measurement reflected light guided by the cable material, and an object to be measured by performing arithmetic processing on the interference light generated by the interference unit A tomographic image calculation unit for generating tomographic image information of A display control unit that displays tomographic image information from the tomographic image calculation unit on a display unit, wherein the display control unit defines the interface position of the photorefractive member of the probe or the transmissive cover body to the tomographic image. An interface detection unit that detects from image information is provided, and the display control is performed so that the display position of the interface position on the display unit is fixed, thereby achieving the intended purpose.

  As described above, the present invention provides a light source, a dividing unit that divides the light emitted from the light source, and a first light divided by the dividing unit provided with a photorefractive member or a transmissive cover body. The probe that irradiates the measurement target from the light input / output unit and takes the reflected light from the measurement target as the measurement reflected light from the light input / output unit, and the first light divided by the division unit to the probe A bendable cable material that guides the measurement reflected light captured by the probe, a reference mirror that corrects the path length of the second light divided by the dividing unit, and a reference mirror from the reference mirror An interference unit that generates interference light by causing interference between the reference light and the measurement reflected light guided by the cable material, and processing the tomographic image information to be measured by calculating the interference light generated by the interference unit The tomographic image calculation unit to be generated and the tomographic image calculation unit A display control unit that displays the tomographic image information of the probe on the display unit, and the display control unit detects the interface position of the photorefractive member of the probe or the transmissive cover body from the tomographic image information. Since the detection unit is provided and the display control is performed so that the display position of the interface position on the display unit is fixed, an accurate optical tomographic image can be displayed.

  That is, the optical tomographic image acquisition apparatus of the present invention detects the interface position of the photorefractive member of the probe or the transmissive cover body from the calculation result of the interference light using the measurement reflected light whose path length has changed. By performing display control so that the interface position is fixed, a display defect due to a change in the path length of the measured reflected light is corrected, so that an accurate optical tomographic image can be displayed.

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 Front view of the display Frequency spectrum diagram of the interference light Flow chart of the control Front view of the display Front view of the display Flow chart of the control

  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 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 bendable 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 is scanned in the uniaxial direction by the optical scanning unit 8, then moved in the direction orthogonal thereto, and then scanned again in the uniaxial direction, that is, the same state as the scanning state for image formation in the conventional CRT television Is scanned.

  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. The light emitted from the light source 18 is divided by the dividing unit 19, and the divided first light is supplied to the optical scanning unit 8 via the bendable cable 5. The scanning in the X-axis direction and the Y-axis direction described above with respect to the above-described tooth 4 is performed.

  The remaining light (second 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 whose path length has been corrected by the reference mirror 20 interferes with the light (measured reflected light) returned through the optical scanning unit 8 and the cable 5, and is converted into an electric signal by the light receiving unit 22. This is converted and supplied to the tomographic image calculation 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 main 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 meshes 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.

  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 applied to the teeth 4 is reflected and passes through the bendable cable 5 and returns to the probe main body 1 side from the protective cover 38 via the prism 10 again as measurement reflected light.

  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, it is mixed with measurement light as reflected light 41 (in other words, non-measurement light) and returned to the probe body 1 side.

  The measurement reflected 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, so that 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 target.

  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. The frequency spectrum of the interference light corresponds to information at a location close to the probe from a low frequency region, and becomes information at a location away from the probe as the frequency increases. In such a correlation, the portion corresponding to 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 has a higher frequency than the second peak 45. It can be obtained by analyzing the region of.

  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.

  First, a method for removing the interface line 44 will be described with reference to FIGS.

  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, since the measurement target does not exist in front of the probe, only the interface line 44 is displayed. Therefore, the gain of the first peak 46 is also obtained in the spectrum distribution of the interference light. (Size) and its frequency 47 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. By removing, accurate tomographic image information of the measurement object can be obtained.

  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.

  As described above, the frequency spectrum of the interference light corresponding to the interface line 44 shown in FIG. 12 appears as the first peak 46 of the frequency spectrum of the interference light shown in FIG. Appears on the lower side of the frequency 45a of the second peak 45 of the frequency spectrum of the interference light hitting the tooth surface.

  In order to obtain such a frequency spectrum distribution, it is necessary to adjust the optical path length of the optical tomographic image acquisition apparatus according to the embodiment of the present invention.

  The optical path length will be described with reference to FIG. 10 again. The light emitted from the light source 20 is divided into two by the dividing unit 21, and one enters the interference unit 23 through the optical path length to the reference mirror 22. On the other hand, the measurement object 4 is irradiated via the light input / output part of the probe described above, the probe captures the reflected light of the measurement object 4 as measurement reflected light, and this measurement light enters the interference part 23. 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. In other words, the optical path length is adjusted so that a point equal to the optical path length X comes to 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.

  If the optical path length X is longer than the optical path length Y, that is, the interface 39 of the prism 10 or the interface 40 of the protective cover 38 as shown in FIG. When the position Y′51 between the teeth 4 is equal to the optical path length X, the tomographic image and the frequency spectrum are as shown in FIGS.

  According to the tomographic image shown in FIG. 16, the tooth tomographic image 43 is displayed on the display screen 42, but below the tomographic image 43, the interface 39 of the prism 10 or the interface 40 of the protective cover described above. The interface line 44 is displayed as an influence of the reflected light 41 to the rear due to.

  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 described above, when the optical path length X is shorter than the optical path length Y, as shown in FIG. 12, the frequency spectrum of the interference light corresponds to information on a portion close to the probe from a low frequency region. However, as the frequency increases, the information becomes the information away from the probe. However, if the optical path length X is longer than the optical path length Y, as shown in FIG. The interface line 44 may be superimposed on the tomographic image 43.

  This is because, when the optical path length X is equal to the optical path length Y at the point Y′51 shown in FIG. 11, the interface 39 between the point Y′51 and the prism 10 or the protection is provided. Since the interface line 44 is displayed from the top of the display screen 42 by an amount corresponding to the distance from the interface 40 of the cover 38, if this distance is longer than the distance between the point Y ′ 51 and the tooth 4, As shown in FIG. 16, the interface line 44 is superimposed and displayed on the tooth tomographic image 43.

  Similarly, in the frequency spectrum of the interference light shown in FIG. 17, the frequency 47 of the first peak 46 corresponding to the interface line 44 is higher than the frequency 45a of the second peak 45 of the frequency spectrum of the interference light hitting the tooth surface. Also appears on the higher side as a frequency.

  The control method in the embodiment of the present invention in such a correlation will be described with reference to FIG. 10. The control unit 26 includes an FFT unit 49 in which interference light from a single probe is provided in the tomographic image calculation unit 25. The position of the reference mirror 22 can be controlled so that the frequency 47 of the first peak 46 of the frequency spectrum of the interference light is equal to or lower than a predetermined frequency.

  A flowchart of this control is shown in FIG.

  The control unit 26 performs the first step of moving the reference mirror 22 so that the optical path length X is shortened, and the control unit 26 performs analysis by the FFT unit 49 provided in the tomographic image calculation unit 25 to obtain the first peak. A second step of determining how the frequency 47 of 46 changes, and if the frequency 47 changes in a lower direction, the optical path of the reference mirror 22 is set so that the frequency 47 is equal to or lower than a predetermined frequency. The third step of moving the length X to be shorter, and if the frequency 47 changes in a higher direction, the optical path length X of the reference mirror 22 is increased so that the frequency 47 is equal to or lower than a predetermined frequency. By performing the fourth step of moving in this manner, 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.

  In this way, the optical path length X from the dividing unit to the interference unit via the reference mirror is less than the optical path length Y from the dividing 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.

  Further, in this state, the non-measurement light removing means removes 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.

  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 By controlling the position of the reference mirror 22, the signal reflected backward from the cover body of the lens and being mixed into the measurement light is removed from the tomographic image information to be measured, so that an accurate optical tomographic image can be acquired. .

  In addition, the use of a prism or protective cover in the optical tomographic image acquisition device makes it possible to change the light irradiation direction of the probe, thereby improving the convenience of the probe and providing a transparent protective cover as the probe. Since it can prevent saliva etc. from entering the probe by providing it at the light entrance / exit part, there is an effect that the hygiene aspect of the probe can be improved.

  Now that the basic configuration and operation of the present embodiment have been understood, the characteristic points of the present embodiment will be described below.

  First, returning to FIG. 10 again, main problems in the present embodiment will be described.

  As described above, in the optical tomographic image acquisition apparatus according to the present embodiment, in order to acquire the optical tomographic image to be measured, the reference light from the reference mirror 20 and the probe guided by the bendable cable material 5 are obtained. The measurement reflected light is caused to interfere with each other to generate interference light, and the interference light generated by the interference unit 21 is arithmetically processed to generate a tomographic image.

  In such a configuration, since the cable member 5 connected to the probe can be bent, the user can easily adjust the position of the probe, so that the operability of the probe can be improved. The phenomenon that the image cannot be displayed correctly occurred.

  This is because the cable member 5 connected to the probe can be bent, and the cable member 5 expands and contracts when bent, and the path lengths of the measurement light guided to the cable member 5 and the measurement reflected light change. As a result, it is found that the tomographic image of the measurement object cannot be displayed accurately because the interference light using the measurement reflected light with the changed path length is calculated and the result is displayed as it is. It was.

  Now, how the display of the tomographic image is not accurately displayed will be specifically described with reference to FIG.

  In FIG. 19, an image interface 44 and a tomographic image 43 of the tooth 4 to be measured are displayed on the display screen 42. As described above, when the interface 44 irradiates 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 light is generated. The reflected light 41 (in other words, non-measurement light) is mixed with the measurement light and returned to the probe body 1 side to be displayed.

  In such a state, if the distance between the probe and the tooth 4 to be measured is fixed, the tomographic image 43 and the interface 44 are fixedly displayed on the display screen 42. When the user operates, the cable material 5 connected to the probe is bent, so that the path lengths of the measurement light guided to the cable material 5 and the measurement reflected light are changed. 19, the display screen 42 moves up and down on the display screen 42 as shown in the display screen 42 of FIG. 20 regardless of the distance between the probe and the tooth 4 to be measured, and is very difficult to see. End up.

  Specifically, in FIG. 20, 44a is the display position of the interface in FIG. 19, and the interface position has been displayed up to the display position of 44b, that is, shifted upward in the display screen. It has become. Similarly, the tomographic image 43 is also displayed while being shifted upward in the display screen.

  Therefore, in order to solve such a problem, as shown in FIG. 10, the configuration of the present embodiment includes a light source 18, a dividing unit 19 that divides the light emitted from the light source 18, and the dividing unit 19. The first light divided in step 1 is irradiated from the light entrance / exit portion provided with the photorefractive member or the transmissive cover body toward the measurement object.

  Next, a probe that takes reflected light from the measurement object as measurement reflected light from the light input / output unit, and guides the first light divided by the dividing unit 19 to the probe, and the measurement taken by the probe A bendable cable member 5 that guides reflected light, a reference mirror 20 that corrects the path length of the second light divided by the dividing unit 19, the reference light from the reference mirror 20, and the cable member 5. Is interfered with the measurement reflected light guided by the interference unit 21 to generate interference light.

  Next, the interference light generated by the interference unit 21 is subjected to FFT calculation processing by the tomographic image calculation unit 23 to generate tomographic image information to be measured. The display control unit 50 further performs the tomographic image information. By detecting the interface position and detecting the interface position, the interface position 52 is controlled so that the interface position is always displayed at a fixed display position on the display screen. The display position can be prevented from moving and the tomographic image can be accurately displayed.

  In other words, as described above, there is an effect that the image information on the interface by the photorefractive member or the transmissive cover body can be easily displayed by detecting / removing the information. By performing the above, it is possible to suppress the vertical blurring of the tomographic image to be measured, and it is possible to obtain the effect that it can be displayed easily.

  Next, FIG. 21 shows a flowchart of processing in the present embodiment.

  First, as a first step, a tomographic image of only the interface is acquired (S1). As a specific acquisition method, for example, the interference light is measured in a state where the probe is placed on the probe installation portion 48 provided on the upper surface of the control box 6 in FIG.

  Next, as a second step, the position of the interface is detected by the interface detection unit (52 in FIG. 10), and the position of the Y coordinate of the display screen is acquired as the reference position y0 (S2).

  Next, the probe is operated to measure the measurement target (S3). In this state, the interface detection unit (52 in FIG. 10) detects the position of the interface from the tomographic image information, and sets this as y1. (S4) The reference position y0 on the Y coordinate of the interface acquired in S2 is compared with the Y coordinate position y1 of the current interface (S5). If the difference is equal to or greater than the threshold, the interface position is y0. Thus, the display control unit (17 in FIG. 10) performs display control for correcting the display position of the entire display screen so that the display screen is displayed in a fixed manner.

  As a means for detecting the interface of the interface detection unit (52 in FIG. 10), there is a means using Hough transform, which is a technique for detecting straight line information in which image information is mixed.

  Alternatively, as described above, the peak of the frequency spectrum generated below a predetermined frequency is detected from the FFT result of the interference light calculated by the tomographic image calculation unit (23 in FIG. 10), and the interface position is detected. Means may be used.

  The interface position of the light refracting member of the probe or the transmissive cover body is detected from the calculation result of such means, that is, the interference light using the measurement reflected light whose path length is changed, and this interface position is fixed. By performing display control as described above, it is possible to correct a display defect due to a change in the path length of the measured reflected light, that is, to shift the display up and down, so that an accurate optical tomographic image can be displayed.

  As described above, the present invention provides a light source, a dividing unit that divides the light emitted from the light source, and a first light divided by the dividing unit provided with a photorefractive member or a transmissive cover body. The probe that irradiates the measurement target from the light input / output unit and takes the reflected light from the measurement target as the measurement reflected light from the light input / output unit, and the first light divided by the division unit to the probe A bendable cable material that guides the measurement reflected light captured by the probe, a reference mirror that corrects the path length of the second light divided by the dividing unit, and a reference mirror from the reference mirror An interference unit that generates interference light by causing interference between the reference light and the measurement reflected light guided by the cable material, and processing the tomographic image information to be measured by calculating the interference light generated by the interference unit The tomographic image calculation unit to be generated and the tomographic image calculation unit A display control unit that displays the tomographic image information of the probe on the display unit, and the display control unit detects the interface position of the photorefractive member of the probe or the transmissive cover body from the tomographic image information. Since the detection unit is provided and the display control is performed so that the display position of the interface position on the display unit is fixed, an accurate optical tomographic image can be displayed.

  That is, the optical tomographic image acquisition apparatus of the present invention detects the interface position of the photorefractive member of the probe or the transmissive cover body from the calculation result of the interference light using the measurement reflected light whose path length has changed. By performing display control so that the interface position is fixed, a display defect due to a change in the path length of the measured reflected light is corrected, so that an accurate optical tomographic image can be displayed.

  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 Tooth 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 part 38 Protective cover 39 Prism interface 40 Protective cover interface 41 Back reflected light 42 Display screen 43 Tomographic image of tooth 44 Interface line 45 Second peak 46 First peak 47 First peak 47 Frequency 48 Probe setting Part 49 FFT unit 50 display control unit 51 the optical path points Y '
52 Interface detector

Claims (5)

A light source, a division unit that divides the light emitted from the light source, and the first light divided by the division unit from the light input / output unit provided with the photorefractive member or the transmissive cover body to the measurement object A probe that takes reflected light from the measurement object as measurement reflected light from the light input / output unit, and guides the first light divided by the dividing unit to the probe, which is taken in by the probe A flexible cable material that guides measurement reflected light, a reference mirror that corrects the path length of the second light divided by the dividing unit, reference light from the reference mirror, and the cable material. An interference unit that generates interference light by interfering with the measurement reflected light that has been guided; and an arithmetic unit for tomographic image that generates tomographic image information to be measured by performing arithmetic processing on the interference light generated by the interference unit; , Display tomographic image information from this tomographic image calculation unit And a display control unit for displaying on,
The display control unit is provided with an interface detection unit for detecting the interface position of the photorefractive member of the probe or the transmissive cover body from the tomographic image information, and the display position of the interface position on the display unit is fixed. An optical tomographic image acquisition apparatus configured to control display. The optical tomographic image acquisition apparatus according to claim 1, further comprising a display unit that displays the tomographic image information generated by the tomographic image calculation unit. The optical tomographic image acquisition apparatus according to claim 1, wherein the interface detection unit is configured to detect the interface position by Hough transform. The optical tomographic image acquisition apparatus according to claim 1, wherein the interface detection unit is configured to detect the interface position from a peak of a frequency spectrum of the interference unit. The optical path length from the dividing unit to the interference unit via the reference mirror is configured to be less than the optical path length from the dividing unit to the interference unit via the light input / output unit of the probe. 5. The optical tomographic image acquisition apparatus according to any one of items 1 to 4.

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