JP5727326B2 - Optical tomographic imaging apparatus and operation control method thereof - Google Patents

Description

  The present invention relates to an optical tomographic imaging apparatus and an operation control method thereof.

  In an optical tomographic imaging apparatus, low coherence light is divided into measurement light and reference light. The measurement light is irradiated onto the measurement object, and the reflected light enters the interference signal generation device. The reference light is applied to a movable reference mirror, and the reflected light enters the interference signal generation device. An interference signal is generated from the reflected light of the measurement light and the reflected light of the reference light incident on the interference signal generation device, and an optical tomographic image of the measurement target is generated from the generated interference signal. If the optical distance difference between the reflected light of the measurement light and the reflected light of the reference light deviates from the coherent distance, an interference signal cannot be obtained. Even if the position of the reference mirror is determined in advance so that an interference signal can be obtained, the distance from the optical probe that irradiates the measurement light to the measurement target is not constant, so the reflected light of the measurement light and the reflected light of the reference light If the optical distance difference deviates from the coherent distance, an interference signal may not be obtained.

  For this purpose, a search is performed by moving the reference plane in a step-like manner (Patent Document 1), a reference length is switched to correct the probe length (Patent Document 2), and individual variations of the probe (Patent Document 3).

JP 2004-105708 A JP 2007-206049 A JP 2010-104514 A

  However, in the invention described in Patent Document 1, since it is not known in which direction and how much the reference plane should be moved, it takes time until an interference signal is obtained, and real-time performance is poor. Moreover, in the invention described in Patent Document 2, when the distance between the optical probe and the measurement object changes, an interference signal may not be obtained.

  An object of the present invention is to obtain an interference signal so that the distance to a measurement object can be known.

  An optical tomographic imaging apparatus according to the present invention uses measurement light / reference light dividing means for dividing low coherent light into measurement light and reference light, and measurement light divided by the measurement light / reference light dividing means as a measurement object. Irradiating measurement light irradiating means, measuring light branching means for branching the measuring light irradiated from the measuring light irradiating means and reflected by the measuring object into n (n is an integer of 2 or more) measuring light optical paths , Reference light branching means for branching the reference light split by the measurement light / reference light splitting means into n reference light optical paths, n reference surfaces for reflecting the reference light emitted from the reference light irradiation means, Each of the reference light branched into the n reference light optical paths by the reference light branching means is reflected by the n reference light irradiating means for irradiating each of the n reference surfaces, and the n reference surfaces. Reference light and above measurement N interference signal generation devices that generate interference signals by causing interference with measurement light branched into n measurement light optical paths by the branching means, and the measurement based on the interference signals generated in the interference signal generation device. A distance calculating means for calculating a distance from the light irradiating means to the measurement target, and an optical tomographic image generating apparatus for generating an optical tomographic image of the measurement target based on the interference signal generated in the interference signal generating apparatus, A first optical distance which is an optical path length of the measurement light from the light / reference light splitting means to the interference signal generation device, and an optical path length of the reference light from the measurement light / reference light splitting means to the interference signal generation device The n types of second optical distances are substantially equal, but each of the n types of second optical distances is different.

  The present invention also provides an operation control method suitable for the optical tomographic imaging apparatus. That is, in this method, the measurement light / reference light dividing means divides the low coherence light into measurement light and reference light, and the measurement light irradiating means is measured light divided by the measurement light / reference light dividing means. The measurement light branching means irradiates the measurement object from the measurement light irradiation means and reflects the measurement light reflected by the measurement object to n (n is an integer of 2 or more) measurement light optical paths. The reference light branching means branches the reference light split by the measurement light / reference light splitting means into n reference light optical paths, and the reference surface reflects the reference light irradiated from the reference light irradiation means. Then, the n reference light irradiating means irradiates each of the n reference surfaces with the reference light branched into the n reference light optical paths by the reference light branching means, so that n interference signals are emitted. The generator is reflected by the n reference surfaces. The interference light is generated by causing the reference light and the measurement light branched into the n measurement light optical paths by the measurement light branching means to interfere with each other, and the distance calculation means converts the interference signal generated by the interference signal generation device into the interference signal. A distance from the measurement light irradiation means to the measurement target is calculated based on the above, and the optical tomographic image generation device generates an optical tomographic image of the measurement target based on the interference signal generated by the interference signal generation device. A first optical distance which is an optical path length of the measurement light from the light / reference light splitting means to the interference signal generation device, and an optical path length of the reference light from the measurement light / reference light splitting means to the interference signal generation device The n types of second optical distances are substantially equal, but each of the n types of second optical distances is different.

  According to the present invention, the low coherence light is divided into the measurement light and the reference light. The measurement light is irradiated onto the measurement object, and the measurement light reflected from the measurement object is branched into n measurement light optical paths. Each of the measurement lights branched into the n measurement light optical paths enters the interference signal generation device. The reference light is branched into n reference light optical paths and irradiated onto each of the n reference surfaces. Each of the reference lights reflected from the n reference surfaces enters the interference signal generation device. The first optical distance, which is the optical path length of the measurement light from the measurement light / reference light splitting means to the interference signal generation device, and the optical path length of the reference light from the measurement light / reference light splitting means to the interference signal generation device The second optical distance is substantially equal so that an interference signal is generated in the interference signal generation device, but each of the n second optical distances is different.

  Since each of the n second optical distances is different, an interference signal is obtained from any one of the reflected light of the n sets of measurement light and the reflected light of the reference light incident on the interference signal generation device. The probability that it can be generated increases. Based on the generated interference signal, the distance from the measurement light irradiation means to the measurement object is calculated. Since the distance to the measurement object is calculated, the optical distance of the measurement light (including the reflected measurement light) can be accurately calculated. Any one of the n reference planes can be moved so that at least one of the n second optical distances is the optical distance calculated accurately. The reference plane can be positioned at a position necessary to obtain an optical tomographic image.

  At least one of the n types of second optical distances based on the n reference light optical paths is from the measurement light irradiation means calculated by the distance calculation means to the measurement target at the first optical distance. Reference surface moving means for moving any one of the n reference surfaces so as to be equal to the corrected first optical distance corrected by the above distance may be further provided.

  It is preferable that a difference in optical distance between each of the n reference light optical paths is equal to or less than a coherence length of the low interference light.

  The ratio of the amount of reflected light of measurement light branched into n reference light optical paths by the measurement light branching means and the ratio of the amount of reference light branched into n reference light optical paths by the reference light branching means are equal. It may be a thing. In this case, the reference plane moving means will move a reference plane that gives an optical distance closest to the corrected first optical distance among the n second optical distances.

  Each of the n interference signal generation devices is irradiated with the reference light irradiated from the n reference light irradiating means and reflected from the n reference surfaces, and n measuring lights are reflected by the measuring light branching means. Each of the measurement lights branched into the optical path may be incident. In this case, the reference surface moving means will move the reference surface on which the reflected light of the reference light is incident on the interference signal generating device having the largest amount of incident light among the n interference signal generating devices.

  Reference planes other than the reference plane moved by the reference plane moving means may be fixed.

  The measurement light irradiation unit may include a focus lens. In this case, a focus control unit that moves the focus lens so that the distance calculated by the distance calculation unit becomes a focal length may be further provided.

  The moving distance of the focus lens by the focusing control means is, for example, the coherence length of the low interference light × n or less.

  The measurement light irradiation unit may include a deflector that deflects the irradiation direction of the measurement light. In this case, a deflector moving unit that moves the deflector so that the distance calculated by the distance calculating unit becomes a focal length may be further provided.

  The moving distance of the deflector by the deflector moving means is, for example, the coherence length of the low interference light × n or less.

  You may further provide the insertion part inserted in a body cavity. In this case, it is preferable that the reference light irradiation means is disposed at the distal end of the insertion portion.

  An endoscope may be included in the insertion portion.

  For example, the reference plane moving means moves the reference plane in the optical axis direction of the reference light.

  The optical tomographic image generated by the optical tomographic image generation apparatus may further include a correcting unit that corrects the optical tomographic image using a moving amount of the reference surface that moves based on the reference surface moving unit.

  The reference light reflected by the reference surface moved by the reference surface moving means is reflected by a reference surface other than the reference surface, rather than the level of the interference signal generated in the interference signal generation device on which the reference light is incident. Reference plane movement control means for controlling the reference plane movement means to move the other reference plane in response to an increase in the level of the interference signal generated in the interference signal generation apparatus on which the reference light is incident. May be further provided. In this case, the optical tomographic image generation apparatus generates an optical tomographic image to be measured from an interference signal obtained from the interference signal generation apparatus based on, for example, control by the reference plane movement control means. The optical tomographic image generated by the optical tomographic image generation apparatus is further provided with a correcting unit that corrects the optical tomographic image using the movement amount of the reference surface that is moved based on the control by the reference surface movement control unit.

1 shows a configuration of an optical tomographic imaging apparatus. (A)-(D) have shown the output signal of the interference signal generation apparatus. It is an example of an optical probe. It is an example of an optical probe. It is a flowchart which shows the process sequence of an optical tomographic imaging apparatus. It is a flowchart which shows the process sequence of an optical tomographic imaging apparatus. 1 shows a configuration of an optical tomographic imaging apparatus. It is a flowchart which shows the process sequence of an optical tomographic imaging apparatus. It is a flowchart which shows the process sequence of an optical tomographic imaging apparatus.

  FIG. 1 shows an embodiment of the present invention and shows the configuration of an optical tomographic imaging apparatus.

  The operation of the optical tomographic imaging apparatus is controlled by the control device 4. A memory 7 for storing predetermined data and the like is connected to the control device 4.

  The optical tomographic imaging apparatus includes a light source 1 that emits laser light L0 in the infrared region while sweeping the wavelength at a constant period. The emitted light L0 from the light source 1 enters the optical fiber F0. The emitted light L0 propagates through the optical fiber F0 and is divided into the measuring light L1 and the reference light L3 by the optical demultiplexer 2 such as an optical fiber coupler. For example, the measurement light L1: the reference light L3 = 90: 10.

  The measurement light L1 divided in the optical demultiplexer 2 propagates through the optical fiber F1 and enters the optical probe 11 from the optical fiber F2 via the circulator 3. The optical probe 11 is disposed at the distal end portion of the insertion portion 10 of the optical tomographic imaging apparatus (endoscope). The insertion portion 10 is inserted into a body cavity or the like, and the measurement light L1 is irradiated from the optical probe 11 to the measurement target Sb in the body cavity. In FIG. 1, the depth direction of the measuring object Sb is the Z axis. The optical probe 11 has a built-in driving device 12 and can move a collimating lens (focus lens) and the like in the optical probe 11 as will be described later. The insertion unit 10 includes a CCD 15. The light bundle representing the measurement object Sb is condensed by the imaging lens 13 and deflected by the prism 14 so as to form an image on the light receiving surface of the CCD 15. A video signal representing the measurement object Sb is output from the CCD 15.

  By irradiating the measuring object Sb with the measuring light L1, the measuring light L1 is reflected from the measuring object Sb and becomes reflected light (reflected measuring light) L2. The reflected light L2 enters the optical demultiplexer 20 through the optical probe 11, the optical fiber F2, the circulator 3, and the optical fiber F3. In the optical demultiplexer 20, the reflected light L2 of the measuring light L1 is first reflected light (reflected measuring light) L21 and second reflected light (reflected measuring light) so that the respective light amounts are equal. It is divided into L22, third reflected light (reflected measurement light) L23 and fourth reflected light (reflected measurement light) L24 (branch to four measurement light optical paths). The first reflected light L21, the second reflected light L22, the third reflected light L23, and the fourth reflected light L24 are transmitted through the optical fibers F4, F5, F6, and F7 to the interference signal generators 21,22. , 23 and 24 respectively.

  The reference light L3 divided by the optical demultiplexer 2 is a first reference whose light quantity is equal by the optical demultiplexer 30 (the optical demultiplexers 2 and 30 may be combined into one). The light is divided into light L31, second reference light L32, third reference light L33, and fourth reference light L34 (branching to four reference light optical paths). The first reference light L31, the second reference light L32, the third reference light L33, and the fourth reference light L34 are the optical fibers F11, F12, F13 and F14, the first circulator 31, and the second reference light L34. The first reference light reflecting device 40, the second reference light reflecting device 50, and the third reference are passed through the circulator 32, the third circulator 33, the fourth circulator 34, and the optical fibers F15, F16, F17, and F18. The light enters the light reflecting device 60 and the fourth reference light reflecting device 70, respectively.

  The first reference light L31 incident on the first reference light reflecting device 40 passes through the collimating lens 41 and irradiates the reference mirror 43 arranged on the base 44. The reference mirror 43 is movable in the optical axis direction by a driving device 45. The first reference light L31 is reflected by the reference mirror 43 and becomes the first reflected light (reflected reference light) L41. The first reflected light L41 is incident on the first interference signal generator 21 via the collimating lens 41, the optical fiber F15, the circulator 31, and the optical fiber F21.

  Similarly to the first reference light L31, the second reference light L32 incident on the second reference light reflecting device 50 is also movable on the base 54 via the collimating lens 51 so as to be movable by the driving device 55. The reference mirror 53 arranged is irradiated. Reflected light (reflected reference light) L42 of the reference mirror 53 is incident on the second interference signal generator 22 via the optical fiber F16, the circulator 32, and the optical fiber F22. Similarly, the third reference light L33 incident on the third reference light reflecting device 60 is also arranged on the base 64 so as to be movable by the driving device 65 via the collimating lens 61. Irradiate 63. Reflected light (reflected reference light) L43 of the reference mirror 63 enters the third interference signal generating device 23 via the optical fiber F17, the circulator 33, and the optical fiber F23. The fourth reference light (reflected reference light) L34 incident on the fourth reference light reflecting device 70 is also arranged on the base 74 so as to be movable by the driving device 75 via the collimating lens 71. The reference mirror 73 is irradiated. The reflected light L72 of the reference mirror 73 enters the fourth interference signal generator 24 via the optical fiber F18, the circulator 34, and the optical fiber F24.

  The measurement light L1 divided by the optical demultiplexer 2 is irradiated to the measurement object Sb, and the reflected light L2 (first reflected light L21 to fourth reflected light L24) is first to fourth interference signal generators. The optical distance to be incident on 21 to 24 is defined as a first optical distance (the optical distance of measurement light from the optical demultiplexer 2 to the interference signal generating devices 21 to 24). Further, the reference light L3 divided by the optical demultiplexer 2 is divided from the first reference light L31 to the fourth reference light L34, and these first reference light L31 to the fourth reference light L34 are reference mirrors. Four types of light reflected from the first reflected light L41 to the fourth reflected light L44 enter the fourth interference signal generating device 24 from the first interference signal generating device 21. Is the second optical distance (the optical distance of the reference light from the optical demultiplexer 2 to the interference signal generators 21 to 24). The optical tomographic imaging apparatus is configured such that the first optical distance and the second optical distance are substantially equal.

  Here, since the reference light L3 branched by the optical demultiplexer 2 is separated from the first reference light L31 to the fourth reference light L34 in the demultiplexer 30, there are four types of optical distances of the reference light. However, here, the first reference light L31 is incident on the first reference light reflector 40, and the first reflected light L41 is incident on the first interference signal generator 21 via the circulator 31. The optical distance of the reference light propagation route, the second reference light L32 enters the second reference light reflector 50, and the second reflected light L42 enters the second interference signal generator 22 via the circulator 32. The optical distance of the second reference light propagation route, the third reference light L33 is incident on the third reference light reflecting device 60, and the third reflected light L43 is generated through the circulator 33 to generate a third interference signal. The optical distance of the third propagation reference beam route incident on the device 23 and the fourth reference beam L34 are the fourth reference beam. The four optical distances of the fourth reference light propagation route that are incident on the light reflecting device 70 and the fourth reflected light L44 is incident on the fourth interference signal generating device 24 via the circulator 34 are shown in FIG. Both are referred to as the second optical distance.

  Any of the optical distance of the first reference light propagation route, the optical distance of the second reference light propagation route, the optical distance of the third reference light propagation route, and the optical distance of the fourth reference light propagation route , Approximately equal to the first optical distance. However, the optical distance of the first reference light propagation route, the optical distance of the second reference light propagation route, the optical distance of the third reference light propagation route, and the optical distance of the fourth reference light propagation route are: , And the optical distance difference equal to or less than the coherent length of the light source 1. Here, the first reference light propagation route, the second reference light propagation route, the third reference light propagation route, and the fourth reference light propagation route are changed to change the optical path length of the optical fiber. The optical distance of the reference light propagation route, the optical distance of the second reference light propagation route, the optical distance of the third reference light propagation route, and the optical distance of the fourth reference light propagation route are changed. Note that the optical distance of the first reference light propagation route, the optical distance of the second reference light propagation route, the optical distance of the third reference light propagation route, and the fourth are not necessarily changed by changing the optical path length of the optical fiber. There is no need to change the optical distance of the reference light propagation route of the optical fiber, the optical path length of the optical fiber is the same, the optical distance from the optical fiber F15 to the reference mirror 43, the optical distance from the optical fiber F16 to the reference mirror 53, The optical distance from the optical fiber F17 to the reference mirror 63 and the optical distance from the optical fiber F18 to the reference mirror 73 may be changed. Alternatively, by changing both the optical path length of the optical fiber and the optical distance from the optical fiber to the reference mirror, the optical distance of the first reference light propagation route, the optical distance of the second reference light propagation route, The optical distance of the third reference light propagation route and the optical distance of the fourth reference light propagation route may be changed.

  From the first interference signal generating device 21 to the fourth interference signal generating device 24, the reflected light L21 to L24 of the measurement light L1 and the reflected light L41 to L44 of the reference light L3 are slightly different in optical distance difference. Since each pair enters, any one of the interference signal generation devices 21 to 24 receives from the reflected lights L21 to L24 of the measurement light L1 having an optical distance difference within the coherent distance and the reflected light L41 of the reference light L3. A pair with L44 is incident. That is, in any of the interference signal generation devices 21-24, interference signals between the reflected lights L21 to L24 of the measurement light L1 and the reflected lights L41 to L44 of the reference light L3 can be generated.

  FIGS. 2A, 2B, 2C, and 2D show output signals of the interference signal generation devices 21, 22, 23, and 24. FIG.

  The optical distance difference between the first reflected lights L21 and L41 incident on the first interference signal generator 21, and the optical distance between the third reflected lights L23 and L43 incident on the third interference signal generator 23 The difference and the optical distance difference between the fourth reflected lights L24 and L44 incident on the fourth interference signal generator 24 are larger than the coherent length, and the second reflected light L22 incident on the second interference signal generator 22 is obtained. The optical distance difference between L42 and L42 is smaller than the coherent length.

  The optical distance difference between the first reflected lights L21 and L41 incident on the first interference signal generator 21, and the optical distance between the third reflected lights L23 and L43 incident on the third interference signal generator 23 Since the optical distance difference between the difference and the fourth reflected lights L24 and L44 incident on the fourth interference signal generator 24 is larger than the coherent length, FIG. 2 (A), FIG. 2 (C), and FIG. As shown in D), no interference signal is generated. On the other hand, since the optical distance difference between the second reflected lights L22 and L42 incident on the second interference signal generator 22 is smaller than the coherent length, as shown in FIG. Is generated. Thus, an interference signal is generated in any one of the interference signal generation devices 21 to 24.

  Returning to FIG. 1, the signal output from the interference signal generation device 21-24 is input to the control device 4.

  Since the interference signal is input to the signal input to the control device 4, the distance from the optical probe 11 to the measurement target Sb is calculated using the input interference signal. This calculation can be realized by using the peak of the interference signal, but since it is a known method as described above, the description thereof is omitted.

  When the distance from the optical probe 11 to the measurement target Sb is calculated, the first optical distance (corrected first optical distance) described above can be accurately obtained. The reflected light incident on the interference signal generating device that outputs the interference signal is input from among the interference signal generating devices 21 to 24 so that the second optical distance described above is the same as the corrected first optical distance. The reference mirror to be moved is moved. For example, as described above, when an interference signal is output from the second interference signal generation device 22, the drive device 55 included in the second reference light reflection device 50 is driven by the control device 4, and the second The reference mirror 53 is moved so that the optical distance of the reference light route is the same as the corrected first optical distance.

  Thereafter, the wavelength-swept laser light is emitted from the light source 1 and the interference signal output from the second interference signal generation device 22 is input to the optical tomography image generation device 5, whereby the optical tomographic image of the measurement target Sb. Is generated. The generated optical tomographic image is displayed on the display screen of the display device 6.

  FIG. 3 shows the configuration of the optical probe 11.

  The optical axes of the first collimating lens 81 and the second collimating lens 82 are substantially perpendicular to the surface of the measuring object Sb. The direction in which the measurement target Sb is irradiated with light is the Z-axis direction.

  The measurement light L1 propagating through the optical fiber F2 is emitted from the optical fiber F2, converted into parallel light by the first collimating lens 81, and guided to the second collimating lens 82. The parallel light incident on the second collimating lens 82 is converged by the second collimating lens 82. The converged measurement light L1 is applied to the measurement object Sb.

  The optical probe 11 includes a driving device 12. The driving device 12 can move the second collimating lens 82 in the optical axis direction (Z-axis direction). The movable distance of the second collimating lens 82 is the coherent length of the emitted light L0 of the light source 1 × 4 (4 because it is branched into four as described above, but n if it is branched into n. ). By moving the second collimating lens 82 in the optical axis direction, the focal position of the second collimating lens 82 moves in the optical axis direction. For example, when the position of the second collimating lens 82 is the position of Z1, the light La1 converged by the second collimating lens 82 is collected on the surface of the measuring object Sb. When the position of the second collimating lens 82 is Z2, the light La2 converged by the second collimating lens 82 is collected inside the measuring object Sb. As will be described later, when the distance from the tip of the optical probe 11 to the surface of the measuring object Sb is known, the second collimating lens 82 is arranged so that the convergent light of the second collimating lens 82 is collected at that distance. To be positioned. Further, the driving device 12 can deflect light converged by the second collimating lens 82 to the XY plane by controlling a deflection mirror (not shown). Thereby, an optical tomographic image within a predetermined range of the measuring object Sb is obtained. If necessary, the driving device 12 is provided outside the optical probe 11.

  FIG. 4 shows another example of the optical probe 11A.

  The surface of the measuring object Sb is parallel to the optical axes of the first collimating lens 81 and the second collimating lens 82. The depth direction of the measuring object Sb is the Z-axis direction.

  As described above, the collimated light is converged by the second collimating lens 82. The converged light is deflected by the prism 85 in the direction of the measuring object Sb. The driving device 12A is capable of moving the prism 85 in the optical axis direction of the first collimating lens 81 and the second collimating lens 83. When the prism 85 is at the position Y1, the light Lb1 deflected by the prism 85 is condensed inside the measurement target Sb. When the prism 85 is moved to the position Y2 farther from the second collimating lens 82 than the position Y1, the light Lb2 deflected by the prism 85 is collected on the surface of the measuring object Sb. When the prism 85 is moved to the position Y3 farther from the second collimating lens 82 than the position Y2, the light Lb3 deflected by the prism 85 is condensed before the surface of the measuring object Sb. In this way, the focal plane position of the second collimating lens 82 can also be controlled by moving the prism 85. The movable distance of the focal plane position is also the coherent length of the outgoing light L0 of the light source 1 × 4. 4, as will be described later, when the distance from the tip of the optical probe 11 to the surface of the measuring object Sb when deflected by the prism 85 is known, the distance (on the surface of the measuring object Sb) is known. The prism 85 is positioned so that the convergent light of the second collimating lens 82 is collected.

  5 and 6 are flowcharts showing the processing procedure of the optical tomographic imaging apparatus.

  As described above, the optical distances between the reflected light L21 to L24 of the four measurement lights incident on the interference signal generating devices 21 to 24 and the reflected lights L41 to L44 of the four reference lights are different. When the infrared laser light whose wavelength is swept from the light source 1 is emitted, an interference signal is detected from at least one of the interference signal generation devices 21 to 24 of the interference signal generation devices 21 to 24 (step 90). Based on the detected interference signal (maximum interference signal when a plurality of interference signals are detected), the distance from the tip of the optical probe 11 to the surface of the measuring object Sb is calculated (step 91). As described above, the distance is calculated based on the peak value of the interference signal.

  When the distance from the tip of the optical probe 11 to the surface of the measurement target Sb is calculated, the measurement light L1 branched by the optical demultiplexer 2 is reflected by the measurement target Sb, and four reflected lights L21, L22, As L23 or L24, an accurate value of the first optical distance until it enters the interference signal generator 21, 22, 23 or 24 can be calculated. As described above, the measurement light L1 branched by the optical demultiplexer 2 is reflected by the measurement object Sb until the measurement light reflected light L21 is incident on the first interference signal generation device 21. The optical distance, the optical distance until the reflected light L22 of the measurement light generated similarly enters the second interference signal generator 22, and the reflected light L23 of the measurement light enters the third interference signal generator 23. The optical distance until the reflected light L24 of the measurement light is incident on the fourth interference signal generating device 24 is the same first optical distance.

  When the accurate first optical distance is calculated, as described above, the four reference light propagation routes (the reference light L31 branched from the reference light L3 branched by the optical demultiplexer 2 into four, The first, second L32, L33 or L34 is reflected by the reference mirror 43, 53, 63 or 73 and enters the interference signal generating device 21, 22, 23 or 24 as reflected light L41, L42, L43 or L44. , 3rd and 4th reference light propagation routes), the second optical distance of the reference light propagation route incident on the interference signal generating apparatus where the interference signal is detected is calculated as the first optical The position of the reference mirror 43, 53, 63 or 73 is moved and adjusted so as to be equal to the target distance (step 93). The adjusted position is the reference light position.

  For example, as shown in FIG. 2B, when an interference signal is detected only from the second interference signal generation device 22, the optical distance of the second reference light propagation route is the first optical signal. It will be the closest to the distance. For this purpose, the position of the reference mirror 53 that causes the reflected light L42 to enter the second interference signal generator 22 is adjusted so that the optical distance of the second reference light propagation route is equal to the first optical distance. Is done. Similarly, when an interference signal is detected only from the interference signal generation device 21, 23 or 24 other than the second interference signal generation device 22, the interference signal generation device 21, 23 or 23 that has generated the detected interference signal is similarly used. The position of the reference mirror 43, 63, or 73 that causes the reflected light L41, L43, or L44 to enter 24 is adjusted.

  Subsequently, the second collimator in the optical probe 11 is adjusted so that the calculated distance from the optical probe 11 to the measurement target Sb becomes the focal length (so that the light is collected on the surface of the measurement target Sb). The lens 82 is positioned (step 94). Since the focal length of the optical system of the optical probe 11 is matched with the distance to the measuring object Sb, a high-quality optical tomographic image can be obtained. As shown in FIG. 4, when the optical probe 11A includes the prism 85, by adjusting the position of the prism 85, the focal length of the optical system of the optical probe 11A becomes the distance to the measurement target Sb. You may make it correspond.

  Subsequently, the wavelength-swept infrared laser beam is emitted from the light source 1 (step 95).

  When the reference mirror 43, 53, 63 or 73 is moved, data representing the moving direction and moving amount of the moved reference mirror is stored in the memory 7 (step 96).

  The optical probe 11 is controlled so that the measurement light L1 irradiates a predetermined range (XY plane scanning) of the measurement target Sb. If the XY plane scanning has not been completed (NO in step 97), the interference signal from which the reflected light from other reference mirrors other than the reference mirror positioned on the reference surface of the interference signal spinners 21 to 24 enters. Whether the level of the interference signal of the generation device has increased from the level of the interference signal based on the reference light incident on the interference signal generation devices 21 to 24 from the reference mirror positioned on the reference surface, or the interference signal that has not been generated It is determined whether the level of the newly generated interference signal has increased from the level of the interference signal based on the reference light incident on the interference signal generation devices 21 to 24 from the positioned reference mirror. (Step 98).

  If the reflected light incident from other reference mirrors has not increased (NO in step 98), the optical probe 11 is controlled so that the emitted measurement light L1 performs XY plane scanning. If the reflected light incident from other reference mirrors increases (YES in step 98), it is considered that the uneven part of the living body is irradiated when the measurement object Sb is being scanned on the XY plane. . That is, the first optical distance changes with XY plane scanning. Also in this case, the distance from the tip of the optical probe 11 to the surface of the measuring object Sb is calculated as described above based on the maximum interference signal obtained from the interference signal generators 21 to 24. The reference mirror is moved. The moving direction and moving amount are stored (step 99).

  When the scanning of the XY plane is completed (YES in step 97), an optical tomographic image of the measurement target Sb is generated while being corrected using the obtained interference signal and the stored movement direction and movement amount (step 101). . For example, the optical tomographic image correction process is performed by adding or subtracting the amount of movement of the reference mirror to or from the distance of the optical tomographic image according to the moving direction. The generated optical tomographic image is displayed on the display screen of the display device 6 (step 102).

  7 to 9 show other embodiments.

  FIG. 7 shows the configuration of the optical tomographic imaging apparatus. In FIG. 7, the same components as those shown in FIG.

  In the optical tomographic imaging apparatus shown in FIG. 1, the reference mirrors 43, 53, 63 and 73 included in the reference light reflecting apparatuses 40, 50, 60 and 70 are movable, but the optical tomographic apparatus shown in FIG. In the imaging apparatus, the reference light mirrors 43, 53, and 63 included in the reference light reflecting devices 40A, 50A, and 60A are fixed and cannot move. However, the reference light mirror 73 included in the reference light reflecting device 70A is movable for a relatively long distance (coherent length of the emitted light L0 of the light source 1 × 4).

  The reference light L3 divided by the optical demultiplexer 2 is branched into four reference lights L31, L32, L33 and L34 by the optical demultiplexer 30A. For example, by branching at a ratio of L31: L32: L33: L34 = 10: 10: 10: 70, the light amount ratio is increased by the light amount of one reference optical path. Reference light having a high light quantity ratio is guided to a reference mirror 73 in which the reference mirror is movable.

  As described above, the distance to the measurement target Sb is calculated from the interference signals detected from the interference signal generation devices 21 to 24, and an accurate first optical distance is obtained. The reference light mirror 73 included in the reference light reflecting device 70A is moved so that the second optical distance is equal to the first optical distance.

  8 and 9 are flowcharts showing the processing procedure of the optical tomographic imaging apparatus shown in FIG. In these figures, the same processes as those shown in FIG. 5 or FIG.

  From the interference signals detected from the interference signal generators 21 to 24 (step 90), the distance to the measuring object Sb is calculated (step 91), and an accurate first optical distance is obtained. The reference light position is calculated so that the second optical distance is equal to the first optical distance (step 92), and the reference light included in the reference light reflecting device 70A is included in the reference light position. The mirror 73 is moved (step 93A).

  If the XY plane scanning is not completed (NO in step 97), the processing from step 95 is repeated. When the XY plane scanning is completed (YES in step 97), an optical tomographic image is generated and displayed (steps 101 and 102). Since the ratio of the amount of light that contributes to image generation is high, the amplitude of the interference signal is high, and an optical tomographic image with a high SN ratio is obtained.

  In the above-described embodiment, it is preferable to move the reference mirror 43 and the like except when the optical probe 11 is moved in the X direction or the Y direction. The maximum movement distance of the second collimating lens 82 included in the optical probe 11 is preferably about the same as the maximum movement distance of the reference mirror 43 and the like.

  In the above-described embodiment, the reflected light of the measurement light and the reference light are each branched into four and made incident on the four interference signal generation devices 21 to 24. However, the number is not limited to four, and n (two or more positive light) It is also possible to use n interference signal generation devices by branching to n or more.

2 Optical demultiplexer (Measuring light / Reference light dividing means)
4 Control device (distance calculation means)
5 Optical tomographic image generator
11, 11A Optical probe (measurement light irradiation means)
20 Optical demultiplexer (reflected light branching means)
30 Optical demultiplexer (reference beam splitter)
40, 40A, 50, 50A, 60, 60A, 70, 70A Reference light reflection device (reference light irradiation means)
21, 22, 23, 24 Interference signal generator

Claims (6)

Measurement light / reference light splitting means for splitting low coherent light into measurement light and reference light,
A measuring light irradiating means for irradiating the measuring object with the measuring light divided by the measuring light / reference light dividing means;
Measurement light branching means for branching the measurement light irradiated to the measurement object from the measurement light irradiation means and reflected by the measurement object into n (n is an integer of 2 or more) measurement light optical paths;
Reference light branching means for branching the reference light split by the measurement light / reference light splitting means into n reference light optical paths;
N reference surfaces for reflecting the reference light irradiated from the reference light irradiation means,
N reference light irradiating means for irradiating each of the n reference surfaces with the reference light branched into the n reference light optical paths by the reference light branching means;
N interference signal generation devices for generating interference signals by causing the reference light reflected by the n reference surfaces to interfere with the measurement light branched into the n measurement light optical paths by the measurement light branching means,
A distance calculating means for calculating a distance from the measuring light irradiating means to the measurement object based on the interference signal generated in the interference signal generating apparatus; and a measurement object based on the interference signal generated in the interference signal generating apparatus. An optical tomographic image generation device for generating an optical tomographic image,
With
A first optical distance which is an optical path length of the measurement light from the measurement light / reference light dividing means to the interference signal generating device, and a reference light of the reference light from the measurement light / reference light dividing means to the interference signal generating device. The optical path length n types of second optical distances are substantially equal, but each of the n types of second optical distances is a different optical tomographic imaging device,
At least one of the n types of second optical distances based on the n reference light optical paths is from the measurement light irradiation means calculated by the distance calculation means to the measurement target at the first optical distance. A reference plane moving means for moving any one of the n reference planes so as to be equal to the corrected first optical distance corrected by the distance of
Further comprising
The ratio of the amount of reflected light of measurement light branched into n reference light optical paths by the measurement light branching means and the ratio of the amount of reference light branched into n reference light optical paths by the reference light branching means are equal. Is,
The reference plane moving means is
Of the n second optical distances, a reference plane that gives an optical distance closest to the corrected first optical distance is moved.
Optical tomographic imaging device. Measurement light / reference light splitting means for splitting low coherent light into measurement light and reference light,
A measuring light irradiating means for irradiating the measuring object with the measuring light divided by the measuring light / reference light dividing means;
Measurement light branching means for branching the measurement light irradiated to the measurement object from the measurement light irradiation means and reflected by the measurement object into n (n is an integer of 2 or more) measurement light optical paths;
Reference light branching means for branching the reference light split by the measurement light / reference light splitting means into n reference light optical paths;
N reference surfaces for reflecting the reference light irradiated from the reference light irradiation means,
N reference light irradiating means for irradiating each of the n reference surfaces with the reference light branched into the n reference light optical paths by the reference light branching means;
N interference signal generation devices for generating interference signals by causing the reference light reflected by the n reference surfaces to interfere with the measurement light branched into the n measurement light optical paths by the measurement light branching means,
Distance calculating means for calculating a distance from the measurement light irradiating means to a measurement object based on the interference signal generated in the interference signal generating device; and
An optical tomographic image generation device for generating an optical tomographic image of a measurement object based on the interference signal generated in the interference signal generation device;
With
A first optical distance which is an optical path length of the measurement light from the measurement light / reference light dividing means to the interference signal generating device, and a reference light of the reference light from the measurement light / reference light dividing means to the interference signal generating device. The optical path length n types of second optical distances are substantially equal, but each of the n types of second optical distances is a different optical tomographic imaging device,
At least one of the n types of second optical distances based on the n reference light optical paths is from the measurement light irradiation means calculated by the distance calculation means to the measurement target at the first optical distance. A reference plane moving means for moving any one of the n reference planes so as to be equal to the corrected first optical distance corrected by the distance of
Further comprising
Each of the n interference signal generation devices is irradiated with the reference light irradiated from the n reference light irradiating means and reflected from the n reference surfaces, and n measuring lights are reflected by the measuring light branching means. Each of the measurement beams branched into the optical path is incident,
The reference plane moving means is
The reference surface on which the reflected light of the reference light is incident on the interference signal generation device having the largest amount of incident light among the n interference signal generation devices is moved .
Optical tomographic imaging device. Reference planes other than the reference plane moved by the reference plane moving means are fixed.
The optical tomographic imaging apparatus according to claim 2. A difference in optical distance between each of the n reference light paths is equal to or less than a coherence length of the low interference light,
The optical tomographic imaging apparatus according to any one of claims 1 to 3. The measuring beam / reference beam splitting means splits the low coherent beam into the measuring beam and the reference beam,
The measuring light irradiating means irradiates the measuring object with the measuring light divided by the measuring light / reference light dividing means,
A measurement light branching unit divides the measurement light irradiated from the measurement light irradiation unit and reflected by the measurement target into n (n is an integer of 2 or more) measurement light optical paths,
The reference light branching means branches the reference light split by the measurement light / reference light splitting means into n reference light optical paths,
n reference surfaces reflect the reference light emitted from the reference light irradiation means,
n reference light irradiating means irradiates each of the n reference surfaces with each of the reference light branched into the n reference light optical paths by the reference light branching means;
n interference signal generation devices generate interference signals by causing the reference light reflected by the n reference surfaces to interfere with the measurement light branched into the n measurement light optical paths by the measurement light branching unit. And
A distance calculation means calculates a distance from the measurement light irradiation means to the measurement object based on the interference signal generated in the interference signal generation device;
An optical tomographic image generation device generates an optical tomographic image of a measurement object based on the interference signal generated by the interference signal generation device,
A first optical distance which is an optical path length of the measurement light from the measurement light / reference light dividing means to the interference signal generating device, and a reference light of the reference light from the measurement light / reference light dividing means to the interference signal generating device. The n types of second optical distances, which are optical path lengths, are substantially equal to each other, but each of the n types of second optical distances is an operation control method of a different optical tomographic imaging apparatus,
The measurement light in which at least one of the n second optical distances based on the n reference light optical paths is calculated by the distance calculation means by the reference surface moving means as the first optical distance. One of the n reference surfaces is moved so as to be equal to the corrected first optical distance corrected by the distance from the irradiation means to the measurement object;
The ratio of the amount of reflected light of measurement light branched into n reference light optical paths by the measurement light branching means and the ratio of the amount of reference light branched into n reference light optical paths by the reference light branching means are equal. Is,
The reference plane moving means moves a reference plane that gives an optical distance closest to the corrected first optical distance among the n second optical distances.
Operation control method of optical tomographic imaging apparatus. The measuring beam / reference beam splitting means splits the low coherent beam into the measuring beam and the reference beam,
The measuring light irradiating means irradiates the measuring object with the measuring light divided by the measuring light / reference light dividing means,
A measuring light branching means for branching the measuring light irradiated from the measuring light irradiation means onto the measuring object and reflected by the measuring object into n (n is an integer of 2 or more) measuring light optical paths;
Branching the reference light split by the measurement light / reference light splitting means into n reference light optical paths;
n reference surfaces reflect the reference light emitted from the reference light irradiation means,
n reference light irradiating means irradiates each of the n reference surfaces with each of the reference light branched into the n reference light optical paths by the reference light branching means;
n interference signal generation devices generate interference signals by causing the reference light reflected by the n reference surfaces to interfere with the measurement light branched into the n measurement light optical paths by the measurement light branching unit. And
A distance calculation means calculates a distance from the measurement light irradiation means to the measurement object based on the interference signal generated in the interference signal generation device;
An optical tomographic image generation device generates an optical tomographic image of a measurement object based on the interference signal generated by the interference signal generation device,
A first optical distance which is an optical path length of the measurement light from the measurement light / reference light dividing means to the interference signal generating device, and a reference light of the reference light from the measurement light / reference light dividing means to the interference signal generating device. The n types of second optical distances, which are optical path lengths, are substantially equal to each other, but each of the n types of second optical distances is an operation control method of a different optical tomographic imaging apparatus,
The measurement light in which at least one of the n second optical distances based on the n reference light optical paths is calculated by the distance calculation means by the reference surface moving means as the first optical distance. One of the n reference surfaces is moved so as to be equal to the corrected first optical distance corrected by the distance from the irradiation means to the measurement object;
Each of the n interference signal generation devices is irradiated with the reference light irradiated from the n reference light irradiating means and reflected from the n reference surfaces, and n measuring lights are reflected by the measuring light branching means. Each of the measurement beams branched into the optical path is incident,
The reference plane moving means moves the reference plane on which the reflected light of the reference light is incident on the interference signal generating apparatus having the largest amount of incident light among the n interference signal generating apparatuses .
Operation control method of optical tomographic imaging apparatus.

Images