JP2011069726A - Distance image acquisition apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a distance image acquisition apparatus which can suppress relative errors between pixels of distance images caused by the bending of a fiber bundle image guide. <P>SOLUTION: The distance image acquisition apparatus 1 includes a flexible armored body 3, a light source 21, a first light-guide fiber 7, a second light-guide fiber 9, a fiber bundle image guide 11 for receiving reflected light and emitting it from a base face 11T, an optical path alteration member 15 for altering the optical path of light emitted from the light source 21 and making it incident onto the fiber bundle image guide 11 as self-calibration light 21E, a distance image sensor 23 for outputting a first output signal corresponding to a first light propagation delay time, and a signal processing part 25 for computing a distance image of an object to be measured 33. The signal processing part 25 computes a second light propagation delay time on the basis of a second output signal of the distance image sensor 23 which has received the self-calibration light 21E and calibrates a distance image for each plurality of pixels on the basis of this. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a distance image acquisition device.

  An endoscope capable of measuring a distance image to a measurement object is known. These endoscopes include a bendable outer body. The reflected light of the measurement object is guided from the distal end portion of the endoscope to the proximal end portion by the fiber bundle type image guide as an image guide provided in the exterior body, and enters the image sensor. The image sensor outputs distance image information of the measurement object. Since the endoscope having such a configuration can be measured even when the exterior body is bent, for example, it is possible to measure a distance image of a measurement object present in a narrow place such as a body cavity.

  The endoscope described in Patent Document 1 below includes two light sources at its base end. Outgoing light from these light sources is guided to the endoscope tip by a light guide fiber, and the two diverging irradiation distances to the measurement object provided at the endoscope tip are respectively changed to the measurement object. Irradiated. And the reflected light by the measuring object of the emitted light of two light sources is measured independently, and the distance from two lenses to a measuring object is calculated from those intensity ratios. A distance image of the measurement object is acquired by such a measurement method.

  As another measurement method for obtaining a distance image, a flight time (TOF) measurement method (hereinafter referred to as “TOF method”) is known. The TOF method is a method of measuring the distance to the measurement object based on the time from when the light source emits the emitted light until the light is reflected by the measurement object and reaches the light receiving element. By performing such distance measurement for a plurality of regions of the measurement object corresponding to the plurality of pixels of the distance image, a distance image having a distance value to the measurement object as a pixel value is obtained.

  An endoscope described in Patent Document 2 below includes one light source provided at a base end portion, a light guide fiber that guides emitted light from the light source to the distal end portion, and irradiates a measurement target, and measurement of irradiation light. A fiber bundle type image guide that receives reflected light from the object at the tip portion and a TOF image sensor that receives the reflected light guided by the fiber bundle type image guide are provided. Reflected light from a plurality of regions of the measurement object is independently guided to the image sensor by a plurality of optical fibers in the fiber bundle type image guide.

JP 2002-65581 A International Publication No. 2005/027739 Pamphlet

  In the endoscope described in Patent Document 1, it is necessary to make the intensities of light irradiated from two light sources to a measurement object equal to each other based on the measurement principle. If there is a difference between these light intensities, an error occurs in the distance measurement. However, such a difference in light intensity is caused by, for example, dirt on the endoscope or deterioration of the light source over time, so it is difficult to completely prevent the difference in intensity. is there. Therefore, in an endoscope that acquires a distance image in the same manner as the endoscope described in Patent Document 1, a distance error in the distance image is caused by a variation in light intensity irradiated to the measurement object. It gets bigger.

  On the other hand, in an endoscope that acquires a distance image by the TOF method as in the endoscope described in Patent Document 2, a light source irradiates light to a measurement object, and then reflects the reflected light to a light receiving element. Since the distance is calculated based on the time until the light is received, an error does not occur in the distance image due to the fluctuation of the light intensity applied to the measurement object.

  During the time from when the light source irradiates the measurement object to when the light receiving element receives the reflected light, the reflected light propagates through the fiber bundle type image guide provided in the exterior body of the endoscope. Time is also included. In calculating the distance to the measurement object, it is necessary to consider the time required for such reflected light to propagate through the fiber bundle image guide (light propagation delay time in the fiber bundle image guide).

  However, when the endoscope outer body is bent, the inner fiber bundle image guide is also bent. And the bending aspect of each optical fiber which comprises a fiber bundle type image guide differs in the inner side and the outer side of a bending part. Typically, an optical fiber inside the bent portion is bent with a relatively small radius of curvature, whereas an optical fiber outside the bent portion is bent with a relatively large radius of curvature. Therefore, the optical propagation delay time in the above-described reflected light fiber bundle image guide is different between the inside and the outside of the bent portion. As a result, in the calculated distance image, an error occurs in the pixel value between the pixels (distance value to each region of the measurement object). That is, due to the bending of the fiber bundle type image guide, a relative error occurs between the pixels of the distance image. In the above-mentioned Patent Documents 1 and 2, there is no mention of errors caused by such bending of the fiber bundle type image guide.

  The present invention has been made in view of such problems, and it is possible to suppress the occurrence of a relative error between pixels of a distance image due to bending of a fiber bundle image guide. An object of the present invention is to provide a distance image acquisition device based on the above.

  In order to solve the above-described problems, a distance image acquisition device according to the present invention is a distance image acquisition device that measures a distance image of a measurement object, and includes a long flexible exterior body and a measurement object. A light source that emits light for projecting light, and a flexible exterior body that is provided so as to extend from the proximal end portion to the distal end portion of the flexible exterior body. A first light guide fiber that receives light and emits the received projection light from the distal end surface, and is provided in the flexible exterior body so as to extend from the proximal end portion to the distal end portion of the flexible exterior body, and is emitted from the light source And a second light guide fiber that emits the received emitted light from the distal end surface, and is provided in the flexible exterior body so as to extend from the proximal end portion to the distal end portion of the flexible exterior body, The reflected light from the measurement object of the projected light is received by the tip surface, and the received reflected light is the base end. The optical path of the fiber bundle type image guide emitted from the optical fiber and the optical path of the emitted light of the light source emitted from the distal end face of the second light guide fiber are changed, and the optical path is changed to be incident on the distal end face of the fiber bundle type image guide as self-calibration light. It is provided to receive the light emitted from the member and the base end face of the fiber bundle type image guide, and has a plurality of light receiving areas corresponding to each of the plurality of pixels of the distance image, and receives the reflected light from the measurement object As a result, the flight time type that outputs the first output signal corresponding to each first light propagation delay time from when the light source emits the projection light until each of the plurality of light receiving regions receives the reflected light. A distance image sensor, and a signal processing unit that calculates a distance image of the measurement object based on the first output signal of the distance image sensor, the signal processing unit Based on the second output signal of the distance image sensor that has received the self-calibration light, each of the second light-receiving areas from when the light source emits the emitted light until each of the plurality of light-receiving regions of the distance image sensor receives the self-calibration light. The light propagation delay time is calculated, and the signal processing unit calibrates the distance image for each of a plurality of pixels based on the second light propagation delay time when calculating the distance image of the measurement object.

  In the distance image acquisition device according to the present invention, the signal processing unit calculates the second light propagation delay time from the second output signal of the flight time type (TOF type) distance image sensor that has received the self-calibration light. Yes. When the fiber bundle image guide is bent, the second light propagation delay time can vary for each of the plurality of light propagation regions in the fiber bundle image guide corresponding to the plurality of light receiving regions of the distance image sensor. There is sex. When the second light propagation delay time varies, the first light propagation delay time includes the same variation. Therefore, when the distance image is calculated from only the first light propagation delay time, the fiber bundle type image guide As a result, a relative error occurs between the pixels of the distance image.

  However, the signal processing unit calculates the second light propagation delay time for each of the plurality of light receiving regions of the distance image sensor. Thereby, in the case of a bending mode with a fiber bundle type image guide, the second light propagation delay time can be grasped for each of the plurality of light propagation regions. The signal processing unit calibrates the distance image for each of the plurality of pixels based on the second light propagation delay time when calculating the distance image of the measurement object from the first output signal. As a result, the relative error between the pixels of the distance image due to the bending of the fiber bundle image guide is suppressed.

  Furthermore, the distance image acquisition device according to the present invention improves the parallelism of the projection light emitted from the distal end surface of the first light guide fiber, and projects the projection light with the improved parallelism onto the measurement object. It is preferable to further include an optical optical member, and a light receiving optical member that improves the concentration of the reflected light from the measurement object and receives the reflected light with the improved concentration on the tip surface of the fiber bundle type image guide. As a result, the intensity of the light projected on the measurement object is increased, and the intensity of the reflected light of the measurement object incident on the fiber bundle image guide is increased, so that a more accurate distance image can be obtained. .

  Furthermore, in the distance image acquisition device according to the present invention, a state in which the light emitted from the light source is incident on the proximal end surface of the first light guide fiber and a state in which the light emitted from the light source is incident on the proximal end surface of the second light guide fiber. It is preferable to further include a switch that reversibly switches the incident state of the light emitted from the light source. This reduces the number of necessary light sources and simplifies the configuration of the device.

  Furthermore, in the distance image acquisition device according to the present invention, it is preferable that the second light guide fiber is provided in a fiber bundle type image guide. Thereby, the light emitted from the distal end surface of the second light guide fiber is emitted from the distal end surface of the fiber bundle type image guide. Then, the light emitted from the front end surface of the fiber bundle type image guide again enters the front end surface of the fiber bundle type image guide as self-calibration light by the action of the optical path changing member. At this time, the traveling direction of the light emitted from the front end surface of the fiber bundle type image guide is changed by about 180 degrees by the optical path changing member. Therefore, the spatial intensity distribution of the self-calibration light is made uniform on the tip surface of the fiber bundle type image guide. As a result, the signal processing unit can calculate the second light propagation delay time with higher accuracy, and thus can obtain a more accurate distance image.

  Furthermore, in the distance image acquisition device according to the present invention, the optical path changing member is preferably formed integrally with the light receiving optical member. Thereby, since the number of required members decreases, the structure of an apparatus is simplified.

  Furthermore, in the distance image acquisition apparatus according to the present invention, the optical path changing member is preferably a mirror surface member or a light diffusing member. Thereby, the distance image acquisition apparatus provided with a mirror surface member or a light-diffusion member as an optical path change member is obtained.

  In the distance image acquisition device according to the present invention, it is preferable that the first light guide fiber and the second light guide fiber are one light guide fiber. Thereby, since the number of light guide fibers with which the distance image acquisition device is provided is reduced, the flexible exterior body can be made thin.

  In this case, the light source can switch between a state in which the light having the first wavelength is emitted and a state in which the light having the second wavelength different from the first wavelength is emitted. Is a wavelength selection mirror that selectively transmits light of the second wavelength and selectively reflects light of the second wavelength, and the light of the first wavelength that has passed through the wavelength selection mirror is projected onto the measurement object as projection light. The light of the second wavelength reflected by the wavelength selection mirror is preferably incident on the tip surface of the fiber bundle type image guide as self-calibrating light. As a result, when the first light guide fiber and the second light guide fiber are one light guide fiber, the light emitted from the tip surface of one light guide fiber can be projected without using a mechanical movable member. It can be divided into light and self-calibration light. As a result, the apparatus can be reduced in size.

  Further, the distance image acquisition device according to the present invention is provided with a preliminary light source and a flexible exterior body so as to extend at least from the base end portion to the distal end portion of the flexible exterior body. A third light guide fiber that receives light from the first end face and emits the received emitted light from the second end face; a light receiving element that receives the emitted light emitted from the second end face of the third light guide fiber; A delay time calculating unit that calculates the light propagation delay time of the outgoing light of the auxiliary light source in the third guide fiber based on the time from when the light is received until the light receiving element receives the light. preferable.

  Thereby, the change degree of the bending mode of the fiber bundle type image guide can be grasped from the light propagation delay time of the outgoing light of the auxiliary light source. As a result, when the degree of change in the bending state of the fiber bundle type image guide becomes a predetermined amount or more, a usage method is possible in which light is emitted from the light source and the light propagation delay time of the self-calibration light is calculated.

  ADVANTAGE OF THE INVENTION According to this invention, the range image acquisition apparatus based on TOF method which can suppress that a relative error arises between each pixel of a range image resulting from the bending of a fiber bundle type image guide is provided. .

It is the schematic which cut | disconnects and shows a part of distance image acquisition apparatus. It is a typical block diagram of a distance image acquisition apparatus. It is sectional drawing cut | disconnected by the plane orthogonal to the length direction of a fiber bundle type image guide. It is a typical block diagram of a distance image sensor. It is a typical block diagram of a distance image acquisition apparatus. It is typical sectional drawing of a flexible exterior body. It is a typical block diagram of a distance image sensor. It is a flowchart which shows the measuring method of a distance image. It is a schematic diagram which shows the structural example of a distance image measurement module. It is a timing chart which shows the example of the switching mode of a measurement mode. It is a figure which shows a distance image typically. It is a typical block diagram of a distance image acquisition apparatus. It is a typical block diagram of a distance image acquisition apparatus. It is a typical block diagram of a distance image acquisition apparatus. It is a timing chart which shows the example of the switching mode of a measurement mode.

  Hereinafter, a distance image acquisition device according to an embodiment will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used for the same elements when possible. In addition, the dimensional ratios in the components in the drawings and between the components are arbitrary for easy viewing of the drawings.

(First embodiment)
First, the distance image acquisition device according to the first embodiment will be described.

  FIG. 1 is a schematic view showing a part of the distance image acquisition device of the present embodiment, and FIG. 2 is a schematic configuration diagram of the distance image acquisition device of the present embodiment. In FIG. 2, the distance image acquisition device is schematically shown, and the light path is bent in the light projecting optical member 13 and the light receiving optical member 17. However, in the actual distance image acquisition device, There is no need to bend the light path.

  As shown in FIG. 1, the distance image acquisition device 1 of the present embodiment includes a flexible exterior body 3, a main body 5, a first light guide fiber 7, a second light guide fiber 9, and a fiber bundle type. An image guide 11, a light projecting optical member 13, an optical path changing member 15, and a light receiving optical member 17 are provided. As shown in FIG. 2, the main body 5 includes a distance image measurement module 27 having a light source 21, a distance image sensor 23, and a signal processing unit 25, and a switch 29.

  As shown in FIG. 1, the flexible exterior body 3 is a long member, for example, a tubular shape. A base end portion 3T of the flexible exterior body 3 is connected to the main body portion 5. The flexible exterior body 3 is made of, for example, a wire mesh or a spiral tube, and can be bent.

  The first light guide fiber 7, the second light guide fiber 9, and the fiber bundle type image guide 11 are respectively in the flexible exterior body 3 from the distal end portion 3L to the proximal end portion 3T of the flexible exterior body 3. It is provided to extend. The first light guide fiber 7 is an optical fiber for guiding the light received by the base end surface 7T to the front end surface 7R and emitting it from the front end surface 7R. Similarly, the second light guide fiber 9 is an optical fiber for guiding the light received by the base end surface 9T to the front end surface 9R and emitting it from the front end surface 9R. The fiber bundle type image guide 11 is an optical fiber bundle for guiding the light received by the distal end surface 11R to the proximal end surface 11T and emitting it from the proximal end surface 11T. When the flexible sheath 3 is bent, the first light guide fiber 7, the second light guide fiber 9, and the fiber bundle type image guide 11 are bent in accordance with the bending manner of the flexible sheath 3. The fiber bundle type image guide 11 is preferably a fiber bundle in which a number of GI type (Graded Index type) optical fibers are bundled from the viewpoint of increasing the aperture ratio.

  As shown in FIG. 2, the light source 21 emits the projection light 21A. For example, the light source 21 emits pulsed projection light 21A at a predetermined cycle. As the light source 21, for example, a high-speed LED (light emitting diode), a laser diode, or a VCSEL (vertical cavity surface emitting laser) can be used.

  The switch 29 includes a first state in which light emitted from the light source 21 is incident on the proximal end surface 7T of the first light guide fiber 7, and a second state in which light emitted from the light source 21 is incident on the proximal end surface 9T of the second light guide fiber 9. It is an element which has the function to switch the incident state of the emitted light of the light source 21 reversibly between states. FIG. 2 shows the first state, and the projection light 21 </ b> A is incident on the base end surface 7 </ b> T of the first light guide fiber 7. As the switch 29, for example, a movable mirror using electromagnetic driving, a shutter, a crystal whose optical path is changed by voltage, or the like can be used.

  The first state is a state for measuring the distance image to the measurement object 33 by the distance image acquisition device 1 (hereinafter referred to as “distance image measurement mode”), and the second state is the distance image acquisition device. This is a state for acquiring calibration data for one distance image (hereinafter referred to as “self-calibration data measurement mode”).

(Distance image measurement mode)
The distance image measurement mode will be described. As shown in FIG. 2, in the distance image measurement mode, the projection light 21A is incident on the proximal end surface 7T of the first light guide fiber 7, guided to the distal end surface 7R, and emitted from the distal end surface 7R as the projection light 21B. To do. The projection light 21 </ b> B is incident on the projection optical member 13. The light projecting optical member 13 is an optical member having a function of collimating and emitting incident light. Parallelization in this case means improving parallelism. Therefore, the projecting optical member 13 improves the parallelism of the projecting light 21 </ b> B, and projects the projecting light 21 </ b> C with improved parallelism onto the measurement object 33. For example, a collimating lens can be used as the light projecting optical member 13. As this collimating lens, for example, a convex lens such as a plano-convex lens can be used. The projected light 21C is preferably substantially parallel light from the viewpoint of improving the intensity of the reflected light 33A described later. The light projecting optical member 13 may be an optical system in which a plurality of lenses are combined.

  The projected light 21 </ b> C is projected onto the measurement object 33, and reflected light 33 </ b> A is generated on the surface of the measurement object 33. The reflected light 33 </ b> A enters the light receiving optical member 17. The light receiving optical member 17 improves the concentration of the reflected light 33A and emits it as reflected light 33B. The reflected light 33 </ b> B is incident on the distal end surface 11 </ b> R of the fiber bundle type image guide 11. As the light receiving optical member 17, for example, a convex lens can be used, and an optical system in which a plurality of lenses are combined can also be used.

  The fiber bundle type image guide 11 guides the reflected light 33B received by the distal end surface 11R to the proximal end surface 11T and emits the reflected light 33C from the proximal end surface 11T as reflected light 33C. The details will be described with reference to FIG.

  FIG. 3 is a cross-sectional view taken along a plane orthogonal to the length direction of the fiber bundle type image guide. As shown in FIG. 3, the fiber bundle type image guide 11 has a plurality of optical fibers 11 </ b> F bundled. The plurality of optical fibers 11F are inserted into, for example, a tubular flexible member 11A, and are fixed only at both ends.

  The fiber bundle type image guide 11 includes a plurality of light propagation regions 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, extending from the distal end surface 11R to the proximal end surface 11T along the flexible member 11A. It has a light propagation region group 11G composed of 11R33, 11R34, 11R41, 11R42, 11R43, and 11R44. Each of the plurality of light propagation regions 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, 11R43, 11R44 is a plurality of pixels P11 of the distance image 37 described later. , P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, P43, and P44, one-to-one correspondence (see FIG. 11).

  Each optical fiber 11F in each light propagation region 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, 11R43, 11R44 of the light propagation region group 11G is measured. A plurality of reflected lights respectively generated in a plurality of surface regions of the object 33 are individually propagated from the distal end surface 11R to the proximal end surface 11T. A set of a plurality of reflected lights generated in a plurality of surface regions of the measurement object 33 becomes reflected light 33B (see FIG. 2). In FIG. 3, each of the light propagation regions 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, 11R43, and 11R44 of the light propagation region group 11G is measured. Each of the plurality of surface regions of the object 33 has a one-to-one correspondence. Each of the plurality of surface regions of the measurement object 33 includes a plurality of pixels P11, P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, which will be described later. One-to-one correspondence with each of P43 and P44.

  In the present embodiment, each of the plurality of light propagation regions 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, 11R43, 11R44 is one. However, it may correspond to a plurality of optical fibers 11F. Further, one optical fiber 11F corresponds to a plurality of the light propagation regions 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, 11R43, 11R44. You may do it.

  As shown in FIG. 2, the reflected light 33B guided from the distal end surface 11R to the proximal end surface 11T by the fiber bundle type image guide 11 is emitted from the proximal end surface 11T as reflected light 33C, and the reflected light 33C is emitted from the distance image sensor 23. Is incident on.

  Details of the distance image sensor 23 will be described with reference to FIG. FIG. 4 is a schematic configuration diagram of the distance image sensor. The distance image sensor 23 is a distance image sensor (flight time type distance image sensor) based on the TOF method. The distance image sensor 23 includes a light receiving region group 23R that receives the reflected light 33C (see FIG. 2). The light receiving region group 23R includes a plurality of light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, 23R44. Each of the plurality of light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, 23R44 is a plurality of pixels P11 of the distance image 37 described later. Each of P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, P43, and P44 has a one-to-one correspondence (see FIG. 11).

  Further, each of the plurality of light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, and 23R44 is the light propagation region 11R11 of the reflected light 33C. , 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, 11R43, and 11R44. Therefore, each of the plurality of light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, 23R44 There is a one-to-one correspondence with each of the surface regions. In FIG. 4, a plurality of light receiving areas 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, 23R44, and a plurality of measurement objects 33 are shown. In order to show the correspondence with each of the surface regions, the measurement object 33 is indicated by a broken line.

  In the distance image measurement mode, the distance image sensor 23 receives the reflected light 33C (see FIG. 2), so that after the light source 21 emits the projection light 21A, the plurality of light receiving regions 23R11, 23R12, 23R13, and 23R14. , 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, and 23R44 each receiving the reflected light 33C (hereinafter referred to as “first light propagation delay time”) .) Is generated and output to the signal processing unit 25 (see FIG. 2).

  In FIG. 4, the first output is represented by the numbers shown in the respective light receiving areas 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, and 23R44. The signal is shown conceptually. These numbers indicate that the smaller the value is, the shorter the first light propagation delay time is, that is, the distance from the distance image acquisition device 1 to each surface region of the measurement object 33 is shorter. As described above, the distance image sensor 23 measures the measurement object for each of the light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, and 23R44. The distance to each surface area 33 is measured, and a first output signal corresponding to the distance to each surface area is generated and output.

  As a method for generating the first output signal of the distance image sensor 23, for example, a charge distribution method and a method of measuring a time crossing a threshold can be cited. In the case of the charge distribution method, the distance image sensor 23 receives each of the light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34 after the light source 21 emits the projection light 21A. , 23R41, 23R42, 23R43, and 23R44 each have a charge proportional to the time until the reflected light 33C is received, and the light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, and 23R32 , 23R33, 23R34, 23R41, 23R42, 23R43, and 23R44, the first output signal is generated. Specifically, in each light receiving area, for example, two storage units A and B are set, and the reflected light is distributed and stored in A and B in proportion to the delay time, and the ratio is calculated. Thus, the delay time and the distance are calculated. In addition, in the case of a method of measuring the time crossing the threshold, a high-speed clock is counted according to the time until the threshold is crossed, or a constant current is integrated according to the time to obtain a voltage corresponding to the time. Thus, the distance image sensor 23 generates the first output signal.

  As shown in FIG. 2, the signal processing unit 25 receives the first output signal from the distance image sensor 23 and calculates a distance image of the measurement object 33 based on the first output signal. For the calculation of the distance image, the signal processor 25 calculates the first light propagation delay time from the first output signal of the distance image sensor 23, and based on the first light propagation delay time, the distance image acquisition device 1 calculates the distance image. This can be done by calculating the distance to each surface region of the measurement object 33. Thus, the distance image of the measurement object 33 is measured in the distance image measurement mode.

  In addition, when calculating the distance image based on the first output signal by the signal processing unit 25 in this way, as will be described in detail later, based on the self-calibration data of the distance image acquired in the self-calibration data measurement mode, Calibrate the distance image.

(Self-calibration data measurement mode)
Next, the self-calibration data measurement mode will be described. FIG. 5 is a schematic configuration diagram of the distance image acquisition apparatus of the present embodiment. As shown in FIG. 5, in the self-calibration data measurement mode, the projection light 21A is incident on the proximal end surface 9T of the second light guide fiber 9, is guided to the distal end surface 9R, and is emitted from the distal end surface 9R as the emitted light 21D. To do. The outgoing light 21 </ b> D enters the optical path changing member 15. The optical path changing member 15 changes the optical path of the outgoing light 21D and makes it incident on the distal end surface 11R of the fiber bundle type image guide 11 as self-calibrating light 21E.

  As the optical path changing member 15, for example, a light reflecting member or a light diffusing member can be used. When a light reflecting member is used as the optical path changing member 15, the optical path changing member 15 can be a member having a reflective film made of a metal such as Al (aluminum) at a position where the emitted light 21D is incident, for example. Further, when a light diffusing member is used as the optical path changing member 15, the optical path changing member 15 is a member having a concavo-convex portion processed into a concavo-convex shape at a position where the emitted light 21D is incident, or a member having a light diffusing portion such as a tape. It can be.

  In the present embodiment, the optical path changing member 15 is separate from the light receiving optical member 17, but the optical path changing member 15 and the light receiving optical member 17 may be integrally formed. In this case, a light reflecting member or a light diffusing member can be provided on a part of the light receiving optical member 17. When a light reflecting member is provided on a part of the light receiving optical member 17, for example, a reflecting film made of a metal such as Al (aluminum) can be provided on a part of the lens as the light receiving optical member 17. Further, when a light diffusing member is provided on a part of the light receiving optical member 17, for example, an unevenness is formed on a part of the lens as the light receiving optical member 17 by surface processing or a diffusing member such as a tape is provided. be able to.

  The self-calibration light 21E incident on the distal end surface 11R is guided from the distal end surface 11R to the proximal end surface 11T by the fiber bundle type image guide 11, and is incident on the distance image sensor 23 as self-calibration light 21F. The distance image sensor 23 receives the self-calibration light 21F, and after the light source 21 emits the projection light 21A, the plurality of light receiving areas 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31. , 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, and 23R44 (see FIG. 4) correspond to respective times until the self-calibration light 21F is received (hereinafter referred to as “second optical propagation delay time”). The second output signal is generated and output to the signal processing unit 25.

  When the fiber bundle type image guide 11 has a substantially linear shape, each light propagation region 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, For each of 11R43 and 11R44, the second optical propagation delay time has substantially the same value. On the other hand, when the fiber bundle type image guide 11 is bent, each light propagation region 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, 11R43 , 11R44, the second optical propagation delay time may vary. This will be described with reference to FIG.

  FIG. 6 is a schematic cross-sectional view of the flexible exterior body. When the flexible sheath 3 is bent as shown in FIG. 6, the first light guide fiber 7, the second light guide fiber 9, and the fiber bundle type image guide 11 are also aligned with the flexible sheath 3. And bend. Paying attention to the bent portion 11B of the fiber bundle type image guide 11, the optical fibers 11F have different bending modes. For example, among the plurality of optical fibers 11F, the outermost optical fiber 11FL of the bent portion 11B is bent relatively gently (that is, the bending rate is relatively small), whereas the bent portion 11B. Among them, the innermost optical fiber 11FS is bent relatively steeply (that is, the bending rate is relatively large).

  Therefore, for example, since the light propagating in the outermost optical fiber 11FL is relatively refracted in the optical fiber 11FL, the light propagates from the distal end surface 11R of the fiber bundle type image guide 11 to the proximal end surface 11T. The optical propagation delay time is relatively small. On the other hand, the light propagating in the innermost optical fiber 11FS is relatively refracted in the optical fiber 11FS, so that the light propagates from the distal end surface 11R to the proximal end surface 11T of the fiber bundle type image guide 11. The optical propagation delay time is relatively large. As described above, when the flexible exterior body 3 is bent, the light propagation regions 11R11, 11R12, 11R13, 11R14, and 11R21 are caused by the bending modes of the optical fibers 11F of the fiber bundle type image guide 11 being different from each other. , 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, 11R43, 11R44 (see FIG. 3), the second optical propagation delay time may vary.

  FIG. 7 is a schematic configuration diagram of the distance image sensor in the self-calibration data measurement mode. In the self-calibration data measurement mode, the distance image sensor 23 receives the self-calibration light 21F as described above to thereby receive a plurality of light receiving areas 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, For each of 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, and 23R44 (see FIG. 4), the second output signal corresponding to the second optical propagation delay time is generated. In FIG. 7, the second output is represented by the numbers shown in the respective light receiving areas 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, and 23R44. The signal is shown conceptually. These numerical values indicate that the smaller the value is, the shorter the second light propagation delay time is.

  The signal processing unit 25 calculates the second light propagation delay time from the second output signal and holds it as self-calibration data. In this way, self-calibration data is measured in the self-calibration data measurement mode.

(Measuring method)
Next, a method for measuring a distance image by the distance image acquisition apparatus of the present embodiment will be described. FIG. 8 is a flowchart showing a distance image measurement method. As shown in FIG. 8, the distance image measurement method by the distance image acquisition apparatus of this embodiment mainly includes a measurement mode selection step S1, a measurement step S3, a calculation step S5, a measurement mode determination step S7, and self-calibration data. It includes a memory step S9, a distance image calculation step S11, a distance image output step S13, and a step S15 for determining the continuation of measurement.

  Such a distance image measurement method will be described together with details of the distance image measurement module. FIG. 9 is a schematic diagram illustrating a configuration example of the distance image measurement module. As shown in FIG. 9, the distance image measurement module 27 includes a light source 21, a distance image sensor 23, and a signal processing unit 25. The signal processing unit 25 supplies power to the control circuit 25A, the pulse generation circuit 25B, the drive circuit 25C, the reading circuit 25D, the arithmetic circuit 25E, the memory 25F, the interface circuit 25G, each circuit, and the memory 25F. Power supply circuit 25H.

  The control circuit 25A controls the entire distance image measurement module 27. In the measurement mode selection step S1, the control circuit 25A sends a light source switching signal to the switch 29. Thereby, when the distance image measurement mode is selected, the light emitted from the light source 21 is switched to the first state in which it enters the proximal end surface 7T of the first light guide fiber 7, and when the self-calibration data measurement mode is selected, the light source 21 Of the second light guide fiber 9 is switched to the second state in which it enters the base end face 9T (see FIGS. 2 and 5).

  In the measurement step S3, the control circuit 25A issues a measurement start command to the pulse generation circuit 25B. The pulse generation circuit 25B supplies a pulse for measurement to the distance image sensor 23 and the reading circuit 25D, and outputs a synchronization signal for lighting the light source 21 to the drive circuit 25C. The drive circuit 25C drives the light source 21 in accordance with the synchronization signal, and emits the projection light 21A (see FIGS. 2 and 5). In the distance image measurement mode, the distance image sensor 23 receives the reflected light 33C (see FIG. 2), and in the self-calibration data measurement mode, the distance image sensor 23 receives the self-calibration light 21F (see FIG. 5).

  In the calculation step S5, the distance image sensor 23 compares the signal from the pulse generation circuit 25B with the received reflected light 33C (or the self-calibration light 21F), and the first light propagation delay time (or the second light propagation time). The first output signal (or the second output signal) corresponding to the delay time) is converted into each light receiving region 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, It is generated for each of 23R43 and 23R44 (see FIGS. 4 and 7). The reading circuit 25D reads the first output signal (or the second output signal) accumulated in the distance image sensor 23 and sends it to the arithmetic circuit 25E. The arithmetic circuit 25E calculates the first optical propagation delay time (or the second optical propagation delay time) from the first output signal (or the second output signal).

  Next, in measurement mode determination step S7, the control circuit 25A determines the measurement mode. If the measurement mode is the self-calibration data measurement mode, the process proceeds to memory step S9 for self-calibration data. In the memory step S9 for self-calibration data, the control circuit 25A accumulates the second light propagation delay time calculated by the calculation circuit 25E in the memory 25F as self-calibration data, and returns to the measurement mode selection step S1. On the other hand, when the measurement mode is the distance image measurement mode, the process proceeds to a distance image calculation step S11.

  In the distance image calculation step S11, the calculation circuit 25E calculates a distance image of the measurement object 33 based on the first light propagation delay time. At that time, the arithmetic circuit 25E calibrates the distance image of the measurement object 33 based on the self-calibration data stored in the memory 25F. This calibration is performed for each light receiving region 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, 23R44 of the distance image sensor 23. Specifically, for each light receiving region 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, 23R44, the first light propagation delay time is The calibration light propagation delay time is calculated by the arithmetic circuit 25E by subtracting the value of the two light propagation delay times. Then, the distance image of the measurement object 33 is calculated by calculating the distances to the plurality of surface regions of the measurement object 33 based on the calibration light propagation delay time by the arithmetic circuit 25E. Each of the plurality of light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, 23R44 is a plurality of pixels P11 of the distance image 37 described later. P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, P43, and P44 have a one-to-one correspondence with each other. This is performed for each of a plurality of pixels.

  This calibration may be performed as follows. First, the first optical propagation delay time is determined by the arithmetic circuit 25E for each of the light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, 23R43, 23R44. Based on the above, non-calibration distances to the plurality of surface regions of the measurement object 33 are respectively calculated. Then, the arithmetic virtual circuit 25E calculates the calibration virtual distance when the second light propagation delay time is virtually associated with the distance to the measurement object. Then, the distance image of the measurement object 33 may be calculated by subtracting the calibration virtual distance from the non-calibration distance for each of the plurality of pixels by the arithmetic circuit 25E. Regardless of which method is used for calibration, the arithmetic circuit 25E calculates a distance image of the measurement object 33 based on the first output signal, and at this time, for each of a plurality of pixels based on the second light propagation delay time. The distance image will be calibrated.

  Thereafter, in the distance image output step S13, the distance image calculated by the calculation circuit 25E is output to the outside as a distance image signal via the interface circuit 25G.

  The mode of switching between the distance image measurement mode and the self-calibration data measurement mode depends on the degree of change in the bending of the flexible exterior body 3 when the distance image acquisition device 1 is used, the accuracy of the distance image required as a specification, and the like. Can be appropriately selected. FIG. 10 is a timing chart illustrating an example of a measurement mode switching mode. When the distance image acquisition device 1 is used, as shown in FIG. 10A, the distance image measurement mode and the self-calibration data measurement mode are alternately measured repeatedly, or as shown in FIG. The combination of measuring once in the predetermined distance image measurement mode and then measuring once in the self-calibration data measurement mode is repeated, or the measurement in the distance image measurement mode is repeated as shown in FIG. When an external trigger is input to the control circuit 25A (see FIG. 9), measurement is performed once in the self-calibration data measurement mode, and thereafter, measurement in the distance image measurement mode is repeated until the external trigger is input again. be able to.

  FIG. 11 is a diagram schematically showing a distance image obtained as described above. In FIG. 11, the distance image 37 is shown in the XYZ orthogonal coordinate system. In FIG. 11, by setting the pixel number of the distance image 37 in the X-axis direction and the Y-axis direction, a plurality of pixels P11, P12, P13, P14, P21, P22, P23, P24 of the distance image 37 in the XY plane. , P31, P32, P33, P34, P41, P42, P43, and P44. Also, a plurality of pixel values V11, V12, V13, respectively corresponding to the plurality of pixels P11, P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, P43, P44, respectively. V14, V21, V22, V23, V24, V31, V32, V33, V34, V41, V42, V43, and V44 are set in the Z-axis direction.

  Each pixel value V11, V12, V13, V14, V21, V22, V23, V24, V31, V32, V33, V34, V41, V42, V43, V44 is a plurality of surfaces of the measurement object 33 from the distance image acquisition device 1. The distance value to each of the areas. The distance image 37 is an image composed of a set of a plurality of distance values as pixel values.

  In the present embodiment, the number of pixels of the distance image 37 is 16. However, as a matter of course, the number of pixels of the distance image 37 is not particularly limited. When the number of pixels of the distance image 37 is larger than the number of the present embodiment, the number of light receiving regions of the distance image sensor 23 also increases so as to correspond to each of the pixels of the distance image 37 (FIG. 4 and FIG. 4). As shown in FIG. 7, the number of light propagation regions of the fiber bundle image guide 11 is increased so as to correspond one-to-one with each of the plurality of light receiving regions.

  In the distance image acquisition device 1 of the present embodiment as described above, the signal processing unit 25 calculates the second light propagation delay time from the second output signal of the distance image sensor 23 that has received the self-calibration light 21F. (See FIGS. 5, 7, and 9). When the fiber bundle type image guide 11 is bent, a plurality of light receiving areas 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, A plurality of light propagation regions 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, 11R43 in the fiber bundle image guide 11 respectively corresponding to 23R43, 23R44, The second optical propagation delay time may vary for each 11R44 (see FIGS. 3, 6, and 7). When the second light propagation delay time varies, the first light propagation delay time also includes the same variation. Therefore, when the distance image 37 is calculated only from the first light propagation delay time, the fiber bundle image Relative to each pixel P11, P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, P43, P44 of the distance image 37 due to the bending of the guide 11 An error occurs (see FIG. 11).

  However, as described above, the signal processing unit 25 includes the plurality of light receiving regions 23R11, 23R12, 23R13, 23R14, 23R21, 23R22, 23R23, 23R24, 23R31, 23R32, 23R33, 23R34, 23R41, 23R42, and 23R43. , 23R44, the second optical propagation delay time is calculated (see FIG. 7). Thereby, in the case of the bending mode with the fiber bundle type image guide 11, a plurality of light propagation regions 11R11, 11R12, 11R13, 11R14, 11R21, 11R22, 11R23, 11R24, 11R31, 11R32, 11R33, 11R34, 11R41, 11R42, The second light propagation delay time can be grasped for each of 11R43 and 11R44. When the signal processing unit 25 calculates the distance image 37 of the measurement object 33 from the first output signal, the signal processing unit 25 has a plurality of pixels P11, P12, P13, P14, P21, P22, based on the second light propagation delay time. The distance image 37 is calibrated for each of P23, P24, P31, P32, P33, P34, P41, P42, P43, and P44. As a result, each pixel P11, P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, P43 of the distance image 37 due to the bending of the fiber bundle image guide 11 The relative error between P44 is suppressed. Therefore, the distance image acquisition apparatus 1 according to the present embodiment can be particularly preferably used as an endoscope capable of measuring a distance image.

  Furthermore, the distance image acquisition device 1 according to the present embodiment improves the parallelism of the projection light 21B emitted from the distal end surface 7R of the first light guide fiber 7, and the projection light 21C with improved parallelism is a measurement target. The light projecting optical member 13 that projects the object 33 and the concentration of the reflected light 33 </ b> A by the measurement object 33 are improved, and the reflected light 33 </ b> B with the improved concentration is received by the distal end surface 11 </ b> R of the fiber bundle type image guide 11. And a light receiving optical member 17 (see FIG. 2). As a result, the intensity of the projection light 21C projected onto the measurement object 33 is increased, and the intensity of the reflected light 33B of the measurement object 33 incident on the fiber bundle image guide 11 is increased. A distance image 37 can be obtained.

  Furthermore, the distance image acquisition device 1 according to the present embodiment includes a light source 21, a first state in which the light projection light 21 </ b> A of the light source 21 is incident on the proximal end surface 7 </ b> T of the first light guide fiber 7, and the light projection light of the light source 21. A switch 29 is provided for reversibly switching the incident state of the projection light 21A of the light source 21 between the second state where 21A is incident on the base end surface 7T of the second light guide fiber 9 (FIGS. 2 and 2). 5). Thereby, since the number of required light sources decreases, the structure of the distance image acquisition apparatus 1 is simplified.

(Second Embodiment)
Next, a distance image acquisition device according to the second embodiment will be described.

  FIG. 12 is a schematic configuration diagram of the distance image acquisition apparatus of the present embodiment in the self-calibration data measurement mode. As shown in FIG. 12, the distance image acquisition device 1a of the present embodiment is the first in terms of the position of the second light guide fiber 9, the configuration of the fiber bundle type image guide 11a, and the position of the optical path changing member 15a. It is different from the distance image acquisition device 1 of the embodiment.

  Specifically, the fiber bundle type image guide 11a of the present embodiment has a second light guide fiber 9 inside. That is, the second light guide fiber 9 is embedded in the fiber bundle image guide 11a. The distal end surface 9R of the second light guide fiber 9 is included in the distal end surface 11aR of the fiber bundle type image guide 11a, and the proximal end surface 9T of the second optical guide fiber 9 is included in the proximal end surface 11aT of the fiber bundle type image guide 11a. It is. Further, the optical path changing member 15 a of this embodiment is formed integrally with the light receiving optical member 17. Specifically, for example, a part of the light receiving optical member 17 is provided with a light reflecting member or a light diffusing member as the light path changing member 15a.

  In the self-calibration data measurement mode of the present embodiment, similarly to the case of the first embodiment, the projection light 21A of the light source 21 is incident on the proximal end surface 9T of the second light guide fiber 9 and from the distal end surface 9R. The light is emitted as emitted light 21D. Then, the outgoing light 21D has its optical path changed by the optical path changing member 15a, and is incident on the front end surface 11aR of the fiber bundle type image guide 11a as self-calibration light 21E. The self-calibration light 21E is guided to the base end face 11aT by the fiber bundle type image guide 11a, is emitted from the base end face 11aT as self-calibration light 21F, and enters the distance image sensor 23.

  Also by the distance image acquisition device 1a of the present embodiment as described above, each pixel P11 of the distance image 37 resulting from the bending of the fiber bundle image guide 11 for the same reason as the distance image acquisition device 1 of the first embodiment. , P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, P43, P44, relative errors are suppressed.

  Furthermore, in the distance image acquisition device 1a of the present embodiment as described above, the second light guide fiber 9 is provided in the fiber bundle type image guide 11. Thereby, the emitted light 21D emitted from the distal end surface 9R of the second light guide fiber 9 is emitted from the distal end surface 11aR of the fiber bundle type image guide 11a. The emitted light 21D emitted from the tip surface 11aR of the fiber bundle type image guide 11a is incident on the tip surface 11aR of the fiber bundle type image guide 11a again as self-calibration light 21E by the action of the optical path changing member 15a. At this time, the traveling direction of the outgoing light 21D emitted from the distal end surface 11aR of the fiber bundle type image guide 11a is changed by about 180 degrees by the optical path changing member 15a. Therefore, the spatial intensity distribution of the self-calibration light 21E is made uniform on the distal end surface 11aR of the fiber bundle type image guide 11a. As a result, the signal processing unit 25 can calculate the second light propagation delay time with higher accuracy, and thus can obtain a more accurate distance image 37.

(Third embodiment)
Next, a distance image acquisition device according to the third embodiment will be described.

  FIG. 13 is a schematic configuration diagram of the distance image acquisition apparatus of the present embodiment. As shown in FIG. 13, the distance image acquisition device 1b of the present embodiment is the first embodiment in that the configuration of the light source 21b, the configuration of the optical path changing member 15b, and the second light guide fiber 9 are not provided. Different from the distance image acquisition apparatus 1 of FIG.

  Specifically, the light source 21b included in the distance image measurement module 27b of the main body 5b of the present embodiment emits the projection light 21Ab having the first wavelength λ1 and the second wavelength λ2 different from the first wavelength λ1. It is possible to switch the state of emitting the projected light 21Ab. The optical path changing member 15b of the present embodiment is a wavelength selection mirror that selectively transmits light having the first wavelength λ1 and selectively reflects light having the second wavelength λ2.

  The projection light 21Ab incident on the base end surface 7T of the first light guide fiber 7 is guided to the distal end surface 7R, and is emitted from the distal end surface 7R as the projection light 21Bb. Then, the projection light 21Bb is incident on the optical path changing member 15b. When the projection light 21Bb is light having the first wavelength λ1, it passes through the optical path changing member 15b and is projected onto the measurement object 33 as the projection light 21Cb via the projection optical member 13. On the other hand, when the projection light 21Bb is light having the second wavelength λ2, it is reflected by the optical path changing member 15b and enters the base end face 11T of the fiber bundle type image guide 11 as self-calibration light 21Eb.

  Therefore, in the present embodiment, the first light guide fiber 7 also functions as the second light guide fiber 9. The light source 21b may be composed of two light sources, a first wavelength light source that emits light of the first wavelength λ1 and a second wavelength light source that emits light of the second wavelength λ2.

  Also by the distance image acquisition device 1b of the present embodiment as described above, each pixel P11 of the distance image 37 resulting from the bending of the fiber bundle type image guide 11 for the same reason as the distance image acquisition device 1 of the first embodiment. , P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, P43, P44, relative errors are suppressed.

  Furthermore, in the distance image acquisition device 1b of the present embodiment, the first light guide fiber 7 also functions as the second light guide fiber 9 as described above. Thereby, since the number of the light guide fibers with which the distance image acquisition apparatus 1b is provided decreases, it becomes possible to make the flexible exterior body 3 thin.

  Further, since the distance image acquisition device 1b of the present embodiment includes the wavelength selection mirror as described above as the optical path changing member 15b, one first light guide fiber 7 is used without using a mechanical movable member. The light emitted from the base end face 7T can be divided into the projection light 21Cb and the self-calibration light 21Eb. As a result, the distance image acquisition device 1b can be reduced in size.

(Fourth embodiment)
Next, a distance image acquisition device according to the fourth embodiment will be described.

  FIG. 14 is a schematic configuration diagram of the distance image acquisition apparatus of the present embodiment in the self-calibration data measurement mode. As shown in FIG. 14, the distance image acquisition device 1 c of the present embodiment is the first embodiment in that the third light guide fiber 41 is further provided, and that the main body unit 5 c is further provided with a delay time calculation unit 51. Different from the distance image acquisition apparatus 1 of FIG.

  The third light guide fiber 41 extends and bends from the proximal end portion of the flexible exterior body 3 to the distal end portion inside the flexible exterior body 3, and further, extends from the distal end portion of the flexible exterior body 3 to the proximal end. It is an optical fiber extending to the part. Two end faces (first end face 41T1 and second end face 41T2) of the third light guide fiber 41 are provided at the base end portion of the flexible sheath 3.

  The delay time calculation unit 51 includes a preliminary light source 43, a light receiving element 45, a drive circuit 47, and a measurement circuit 49.

  The third light guide fiber 41 and the delay time calculation unit 51 are a bending detection mechanism for detecting the bending of the fiber bundle type image guide 11. The measurement circuit 49 issues a command to start bending detection to the drive circuit 47. The drive circuit 47 drives the auxiliary light source 43 and emits, for example, pulsed emitted light from the auxiliary light source 43. The outgoing light from the auxiliary light source 43 enters the first end face 41T1 of the third light guide fiber 41. The third light guide fiber 41 guides the emitted light received by the first end face 41T1 to the second end face 41T2 and emits it toward the light receiving element 45. The light receiving element 45 receives the light emitted from the second end face 41T2 and sends a light reception signal to the measurement circuit 49. The measurement circuit 49 calculates the fiber bundle type image guide from the light propagation delay time (the light propagation delay time of the emitted light of the preliminary light source 43) from when the preliminary light source 43 emits the emitted light until the measuring circuit 49 receives the light. 11 bends are detected. That is, when the flexible outer casing 3 is bent and the fiber bundle type image guide 11 is bent accordingly, the third light guide fiber 41 is also bent according to the flexible outer casing 3, so that the light propagation delay time is increased. Changes. It is possible to detect the bending of the fiber bundle type image guide 11 from the change in the light propagation delay time. The measurement circuit 49 sends a bending detection signal to the signal processing unit 25.

  Also by the distance image acquisition device 1c of the present embodiment as described above, each pixel P11 of the distance image 37 resulting from the bending of the fiber bundle type image guide 11 for the same reason as the distance image acquisition device 1 of the first embodiment. , P12, P13, P14, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42, P43, P44, relative errors are suppressed.

  Furthermore, according to the distance image acquisition device 1c of the present embodiment as described above, the degree of change in the bending state of the fiber bundle image guide 11 can be grasped from the light propagation delay time of the light emitted from the auxiliary light source 43. Therefore, when the degree of change in the bending mode of the fiber bundle type image guide 11 exceeds a predetermined amount, the switch 29 switches to the self-calibration data measurement mode, emits light from the light source 21, and emits light of the self-calibration light 21E. The usage method of calculating the propagation delay time becomes possible.

  FIG. 15 is a timing chart showing an example of a measurement mode switching mode in the present embodiment. As shown in FIG. 15, when using the distance image acquisition device 1c, the measurement in the distance image measurement mode is repeated, and the self-calibration data measurement mode is detected when the delay time calculation unit 51 detects a bend of a predetermined amount or more. The measurement method can be used in such a manner that the measurement in the distance image measurement mode is repeated until the delay time calculation unit 51 detects the bending of a predetermined amount or more again.

  Note that the above-described bending detection mechanism (the third light guide fiber 41 and the delay time calculation unit 51) may be further provided in the distance image acquisition device 1a of the second embodiment or the distance image acquisition device 1b of the third embodiment. Good.

  The present invention is not limited to the above embodiment, and various modifications can be made.

  For example, the distance image acquisition devices 1, 1a, 1b, and 1c of the first to fourth embodiments described above each include one light source (light source 21 or light source 21b) (FIGS. 2, 5, and 12). , FIG. 13 and FIG. 14), each may include two light sources (first light source and second light source). In this case, in the first embodiment, the second embodiment, and the fourth embodiment (FIGS. 2, 5, 12, and 14), the distance image acquisition devices 1, 1a, and 1c include a switch 29. The light emitted from the first light source is incident on the proximal end surface 7T of the first light guide fiber 7, and the light emitted from the second light source is incident on the proximal end surface 9T of the second light guide fiber 9. In the third embodiment (FIG. 13), the first light source emits outgoing light including light having the first wavelength λ1 toward the base end surface 7T of the first light guide fiber 7, and the second light source Outgoing light including light having two wavelengths λ <b> 2 is emitted toward the base end face 7 </ b> T of the first light guide fiber 7.

  In the distance image acquisition devices 1, 1a, 1b, and 1c of the first to fourth embodiments described above, the distance image sensor 23 functions to measure an image image (grayscale image or color image) of the measurement object 33. May further be included. In this case, a distance image in a mode corresponding to the image image of the measurement object 33 can be obtained.

  Further, the distance image acquisition devices 1, 1a, 1b, and 1c of the first to fourth embodiments described above further include an image image sensor (grayscale image sensor or color image sensor) separate from the distance image sensor 23. You may do it. Also in this case, it is possible to obtain a distance image in a mode corresponding to the image of the measurement object 33.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c ... Distance image acquisition apparatus, 3 ... Flexible exterior body, 5, 5b, 5c ... Main-body part, 7 ... 1st light guide fiber, 9 ... 2nd light guide fiber, 11, 11a ... Fiber bundle type image guide, 13 ... Projection optical member, 15, 15a, 15b ... Optical path changing member, 21, 21b ... Light source (first Light source, second light source), 21A, 21B, 21C... Projection light, 23... Distance image sensor, 25... Signal processing unit, 27. Object, 33A, 33B, 33C ... reflected light.

Claims (9)

A distance image acquisition device for measuring a distance image of a measurement object,
A long flexible outer casing;
A light source that emits projection light for projecting onto the measurement object;
The flexible exterior body is provided so as to extend from the proximal end portion to the distal end portion of the flexible exterior body. The projected light emitted from the light source is received by the proximal end surface, and the received projected light is received. A first light guide fiber that is emitted from the distal end surface;
It is provided in the flexible exterior body so as to extend from the base end portion to the distal end portion of the flexible exterior body, receives the emitted light of the light source at the proximal end surface, and receives the received emitted light from the distal end surface A second light guide fiber to be emitted;
The flexible exterior body is provided so as to extend from the base end portion to the distal end portion of the flexible exterior body, and the reflected light from the measurement object of the projected light is received at the distal end surface and received. A fiber bundle type image guide for emitting the reflected light from the base end surface;
An optical path changing member that changes the optical path of the emitted light of the light source that exits from the distal end face of the second light guide fiber, and that enters the distal end face of the fiber bundle type image guide as self-calibrating light;
The reflected light from the measurement object is provided so as to receive light emitted from the base end face of the fiber bundle type image guide, and has a plurality of light receiving regions corresponding to a plurality of pixels of the distance image. The first output signal corresponding to each first light propagation delay time from when the light source emits the projected light to when each of the plurality of light receiving regions receives the reflected light. A flight time type distance image sensor to output,
A signal processing unit that calculates the distance image of the measurement object based on the first output signal of the distance image sensor;
With
The signal processing unit, based on the second output signal of the distance image sensor that has received the self-calibration light, each of the plurality of light receiving regions of the distance image sensor after the light source emits the emitted light. Calculate each second light propagation delay time until the self-calibration light is received,
The signal processing unit calibrates the distance image for each of the plurality of pixels based on the second light propagation delay time when calculating the distance image of the measurement object. . A light projecting optical member that improves the parallelism of the projected light emitted from the distal end surface of the first light guide fiber, and projects the projected light with improved parallelism onto the measurement object;
A light receiving optical member for improving the light collection degree of the reflected light by the measurement object, and for receiving the reflected light with the improved light collection degree on the tip surface of the fiber bundle type image guide;
The distance image acquisition device according to claim 1, further comprising:   Between the state in which the emitted light of the light source is incident on the proximal end surface of the first light guide fiber and the state in which the emitted light of the light source is incident on the proximal end surface of the second light guide fiber The range image acquisition apparatus according to claim 1, further comprising a switch that reversibly switches the incident state of the emitted light.   The distance image acquisition device according to any one of claims 1 to 3, wherein the second light guide fiber is provided in the fiber bundle type image guide.   The distance image acquiring apparatus according to claim 1, wherein the optical path changing member is integrally formed with the light receiving optical member.   The distance image acquiring apparatus according to claim 1, wherein the optical path changing member is a mirror member or a light diffusing member.   The distance image acquisition apparatus according to claim 1, wherein the first light guide fiber and the second light guide fiber are one light guide fiber. The light source can switch between a state of emitting light of a first wavelength and a state of emitting light of a second wavelength different from the first wavelength,
The optical path changing member is a wavelength selection mirror that selectively transmits the light of the first wavelength and selectively reflects the light of the second wavelength,
The light of the first wavelength transmitted through the wavelength selection mirror is projected onto the measurement object as the projection light,
8. The distance image acquisition apparatus according to claim 7, wherein the light having the second wavelength reflected by the wavelength selection mirror is incident on the distal end surface of the fiber bundle type image guide as the self-calibration light. A spare light source;
The flexible exterior body is provided so as to extend at least from the base end portion to the distal end portion of the flexible exterior body, and the emitted light emitted from the preliminary light source is received by the first end surface, and the received emitted light is received. A third light guide fiber that emits light from the second end face;
A light receiving element that receives the emitted light emitted from the second end face of the third light guide fiber;
A delay time for calculating a light propagation delay time of the emitted light of the preliminary light source in the third guide fiber based on a time from when the preliminary light source emits light until the light receiving element receives the light. An arithmetic unit;
The distance image acquisition device according to claim 1, further comprising:

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