JP2007252774A - Optical tomography imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical tomography imaging apparatus which is suitable for reduction of overall equipment size. <P>SOLUTION: The optical tomography image apparatus X comprises a first light source 10 emitting light having a wavelength of a first wavelength band, a second light source 20 emitting light having a wavelength of a second wavelength band different from the first wavelength band, a branching and multiplexing means 21 to transmit reflected light at the time when light emitted from the first light source 10 is cast on a portion L to be irradiated with the light, to branch the light emitted from the second light source 20 into measurement light cast on an object M to be measured and reference light cast on a reflecting member 35 and to multiplex reflected measurement light at the time when the measurement light is cast on the portion M to be measured and reflected reference light at the time when the reference light is cast on the reflection member 35, and a light receiving element 24 receiving interference light made by multiplexing the reflected measurement light and the reflected reference light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical tomographic imaging apparatus used for diagnosis for industrial or medical purposes. In particular, the present invention relates to an endoscope combined optical tomographic imaging apparatus used in OCT (Optical Coherence tomography) for medical endoscopes.

  OCT, which is an optical tomographic imaging apparatus, is established as a means for observing a tomographic image of the retina in, for example, an ophthalmic region. OCT can also be applied to endoscopes, and since there is a possibility of realizing an optical axis direction resolution close to 10 times that of conventional ultrasonic endoscopes, various developments are underway. . Such an endoscope with a built-in OCT is disclosed in Patent Document 1, for example.

  FIG. 3 is a diagram illustrating a schematic configuration of the endoscope Y disclosed in Patent Document 1. As illustrated in FIG. The endoscope Y includes an endoscope main body section 60, an OCT section 70, a signal processing section 80, and a monitor 90. The endoscope main body 60 includes a light source device 61, a light guide 62, an objective optical system 63 including a half mirror 63a and a zoom lens 63b, an image sensor (CCD) 64, and a scanning mechanism including scanning mirrors 65a and 65b. 65, a mirror 66, and a lens 67. The OCT unit 70 includes an SLD (Super Luminescent Diode) 71, a single mode fiber 72, a coupler 73, a single mode fiber 74, an actuator 75, and a PD (Photo Diode) 76.

  Light emitted from the light source device 61 for surface observation is irradiated to the irradiated portion (for example, biological tissue) L through the light guide 62. The reflected light from the irradiated portion L is received by the image sensor 64 via the objective optical system 63 and converted into a signal. The signal output from the image sensor 64 is processed by the signal processing unit 80, and the processing result (image image) is displayed on the monitor 90.

On the other hand, the low coherence light from the SLD 71, which is a low coherence light source (broadband light source), is guided to the distal end side of the endoscope main body 60 through the single mode fiber 72, the coupler 73, and the single mode fiber 74, and the lens. 67, the mirror 66, the scanning mechanism 65, and the half mirror 63a. The reflected light from the measurement target M is received by the PD 76 via the half mirror 63a, the scanning mechanism 65, the mirror 66, the lens 67, the single mode fiber 74, the coupler 73, and the single mode fiber 72, and converted into a signal. The reflected light is combined with the reference light reflected from the actuator 75 by a part of the light emitted from the SLD 71 by the coupler 73 to become interference light. The signal output from the PD 76 is processed by the signal processing unit 80, and the processing result (image image) is displayed on the monitor 90.
Japanese Patent Application Laid-Open No. 11-56751

  However, the endoscope Y disclosed in Patent Document 1 has an imaging element 64 for observing the surface of the irradiated portion L and a PD 76 for obtaining a measurement image (tomographic image) of the measured portion M. Therefore, it is difficult to reduce the size of the entire apparatus. This problem is particularly noticeable in endoscopes that have a high demand for downsizing.

  The present invention has been conceived under such circumstances, and an object thereof is to provide an optical tomographic imaging apparatus suitable for reducing the size of the entire apparatus.

  An optical tomographic imaging apparatus according to the present invention includes a first light source that emits light having a wavelength in a first wavelength band, and a second light source that emits light having a wavelength in a second wavelength band different from the first wavelength band. Then, the reflected light when the light emitted from the first light source is irradiated to the irradiated portion is transmitted, and the light emitted from the second light source is irradiated to the measured portion. While demultiplexing the measurement light and the reference light applied to the reflective member, the reflective measurement light and the reference light when the measurement light is applied to the part to be measured are applied to the reflective member. A multiplexing / demultiplexing unit that multiplexes the reflected reference light when received, and a light receiving element that receives the reflected light and receives interference light formed by multiplexing the reflected measurement light and the reflected reference light. It is characterized by providing.

  In the present optical tomographic imaging apparatus, the multiplexing / demultiplexing means preferably includes a pair of triangular prisms constituting a rectangular parallelepiped and a dielectric multilayer film formed on opposing surfaces of the pair of prisms.

  The optical tomographic imaging apparatus includes a first light guide member for guiding light emitted from a first light source, a second light guide member for guiding light emitted from the second light source, and the second light guide. It is preferable to further include a collimator that is connected to the end of the optical member on the side of the multiplexing / demultiplexing means and converts the emitted light from the second light guide member into substantially parallel light.

  The optical tomographic imaging apparatus preferably further includes an image fiber formed by bundling a plurality of optical fibers between the multiplexing / demultiplexing unit and the light receiving element.

  In the optical tomographic imaging apparatus, the first wavelength band is preferably a visible light wavelength band.

  In the optical tomographic imaging apparatus, the second wavelength band is preferably a wavelength band of near infrared light.

  In the present optical tomographic imaging apparatus, the second light source is preferably a wavelength tunable laser having a wavelength conversion function in the second wavelength band.

  The optical tomographic imaging apparatus according to the present invention transmits the reflected light when the light emitted from the first light source is irradiated to the irradiated portion and transmits the light emitted from the second light source to the measured portion. Is divided into the measurement light irradiated to the reference light and the reference light irradiated to the reflecting member, and the reflected measurement light and the reference light when the measurement light is irradiated to the measured part are applied to the reflecting member. A multiplexing / demultiplexing unit that multiplexes the reflected reference light when irradiated with the light, and a light receiving element that receives the reflected light and receives the interference light formed by combining the reflected measurement light and the reflected reference light. I have. That is, the multiplexing / demultiplexing means has a function of transmitting the reflected light when the light emitted from the first light source is irradiated to the irradiated portion, and the light receiving element receives the interference light as well as the reflected light. It has a function to do. Therefore, in this optical tomographic imaging apparatus, it is possible to secure a region through which irradiation light (or reflected light) passes separately from a region through which measurement light (or reflected measurement light) and reference light (or reflected reference light) pass. In addition to this, it is not necessary to provide a light receiving element for receiving irradiation light (or reflected light) separately from a light receiving element for receiving measurement light (or reflected measurement light) and reference light (or reflected reference light). Therefore, in the present optical tomographic imaging apparatus, it is possible to reduce the size of the part from which the measurement light and the irradiation light are emitted, and to reduce the number of parts, so that the cost can be reduced.

  When the multiplexing / demultiplexing means of the present optical tomographic imaging apparatus includes a pair of triangular prisms constituting a rectangular parallelepiped and a dielectric multilayer film formed on the opposing surfaces of the pair of prisms, the wavelength of the first light source Since the light transmission characteristic with respect to the band is large, the light reflected from the irradiated portion can be received more efficiently in the light receiving element.

  In this optical tomographic imaging apparatus, each light guide member for guiding the light emitted from each light source and the end of the second light guide member on the side of the multiplexing / demultiplexing means are connected to each other. In the case of further comprising a collimator for converting the emitted light into substantially parallel light, the measurement light and the emitted light can be appropriately emitted without arranging each light source in the vicinity of the portion from which the measured light or emitted light is emitted. Can do. Usually, since the optical fiber etc. which are employ | adopted as each light guide member are smaller than various light sources, the optical tomography imaging apparatus of this structure is suitable when aiming at size reduction of the site | part which radiate | emits measurement light and irradiation light. In addition, since the light emitted through the second light guide member can be converted into substantially parallel light by the collimator, the emitted light can be widened to enlarge the measurement area.

  In the present optical tomographic imaging apparatus, when an image fiber formed by bundling a plurality of optical fibers is further provided between the multiplexing / demultiplexing means and the light receiving element, the multiplexing is not necessary even if the light receiving element is not disposed near the multiplexing / demultiplexing means. Interfering light combined by the demultiplexing means can appropriately reach the light receiving element. Since the image fiber is usually smaller in size than various light receiving elements, the optical tomographic imaging apparatus of this configuration is suitable for reducing the size in the vicinity of the multiplexing / demultiplexing means.

  In this optical tomographic imaging apparatus, when the first wavelength band of the first light source is in the visible light region, the light emitted from the first light source can be used as a guide light that illuminates the irradiated portion. Therefore, the present optical tomographic imaging apparatus is suitable for appropriately moving a portion that emits measurement light or irradiation light to a target position.

  In the present optical tomographic imaging apparatus, when the second wavelength band of the second light source is set to the near infrared light region, the measurement light applied to the measurement target can reach the inside of the living body, for example. It is suitable for obtaining a tomographic image inside.

  When the second light source is a tunable laser having a wavelength conversion function in the second wavelength band in the optical tomographic imaging apparatus, the reflected measurement light and the reflected reference light are combined by changing the wavelength of the tunable laser. Since the interference light formed by waves can be obtained, a movable mechanism member (for example, a flexible shaft for scanning the measurement light emitted from the prism) is not disposed in the vicinity of the portion from which the measurement light or irradiation light is emitted. I'm sorry. Therefore, the present optical tomographic imaging apparatus is suitable for reducing the size of the vicinity of the part that emits the measurement light and the irradiation light. Further, the present optical tomographic imaging apparatus can prevent the vibration caused by the movement of the movable mechanism member from being driven with respect to the measurement target, and can also prevent the measurement signal from generating noise due to this vibration. .

  FIG. 1 is an enlarged perspective view of a main part showing a schematic configuration of an optical tomographic imaging apparatus X according to the present invention. 2 is an enlarged view of a main part of the optical tomographic imaging apparatus X shown in FIG. 1, wherein (a) is a side view and (b) is another side view. The optical tomographic imaging apparatus X has a structure in which a structure A that functions as an endoscope for surface observation and a structure B that functions as a Michelson interferometer-based wavelength scanning interferometer are integrated.

  The structure A includes an illumination light source 10, a light guide 11, and an illumination lens 12 that are included only in the structure A, and a beam expanding unit 20, a multiplexing / demultiplexing unit 21, a pair of lenses 22, and an aperture 23 that are also included in the structure B described later. A CCD sensor 24, a memory 25, a calculation means 26, a display means 27, and a control means 28.

  The illumination light source 10 is, for example, a member that emits illumination light for illuminating the surface of the body, and for example, a high-intensity lamp (for example, a xenon lamp, a halogen lamp, an LED, or a semiconductor laser) is employed. Illuminating light includes visible light (wavelength: about 400 to 800 nm).

  The light guide 11 is a member for guiding the illumination light emitted from the illumination light source 10 to an illumination lens 12 described later, and is constituted by an optical fiber, for example.

  The illumination lens 12 is a member for irradiating the irradiated portion L (for example, the surface of the body) with the illumination light emitted through the light guide 11 as diffused light.

  The beam expanding means 20 is a member for expanding the beam diameter of light, and is formed of, for example, a glass body having a concave portion on the surface. By providing the beam expanding means 20 having such a configuration, the beam diameter is expanded, so that the measurable region can be expanded. The beam expanding means 20 is bonded to the surface of the multiplexing / demultiplexing means 21 described later via, for example, a translucent resin (for example, epoxy resin) or low melting point glass.

  The multiplexing / demultiplexing means 21 transmits the reflected light when the irradiated portion L is irradiated with the illumination light emitted from the illumination light source 10 and transmits the light emitted from the wavelength tunable laser 30 to be described later. The measurement light applied to M and the reference light applied to the reflection member described later are demultiplexed, and the reflected measurement light and reference light when the measurement light is applied to the measurement target M are separated. It is a member that combines the reflected reference light when irradiated on the reflecting member, and is configured, for example, in a substantially rectangular parallelepiped shape (cube shape). Specifically, the multiplexing / demultiplexing means 21 is a dielectric multilayer formed on a pair of triangular prisms 21a and 21b constituting a rectangular parallelepiped, and opposing surfaces (inclined surfaces in the drawing) of the pair of triangular prisms 21a and 21b. And a film 21c. The dielectric multilayer film 21c has a function of transmitting illumination light emitted from the illumination light source 10, and a member of a half mirror (semi-transparent mirror) function for light emitted from the wavelength tunable laser 30. It is.

  The pair of lenses 22 is a member for forming an image of interference light formed by combining the reflected measurement light and the reflected reference light on the CCD sensor 24, which will be described later, by the multiplexing / demultiplexing means 21, and is constituted by a pair of convex lenses, for example. An optical system.

  The aperture 23 is a member for removing unnecessary signals (noise) included in the reflected measurement light from the measurement target M. For example, light within a predetermined angle is selected from the reflection measurement light from the measurement target M. And a spatial filter that can be passed through.

  The CCD sensor 24 is a member for receiving interference light formed by combining the reflected measurement light and the reflected reference light by the multiplexing / demultiplexing means 21 and converting it into a signal (interference signal). An element is mentioned.

  The memory 25 is a part having a function for recording a signal obtained from the CCD sensor 24.

  The computing unit 26 has a function of computing (for example, digital Fourier transform) information related to a three-dimensional image (or two-dimensional image) of the measurement target M based on a signal recorded in the memory 25. Digital Signal Processor).

  The display means 27 is for actually displaying, as an image, information related to the three-dimensional image (or two-dimensional image) of the part M to be measured calculated by the calculation means 26, and examples thereof include a liquid crystal display device.

  The control means 28 controls the lighting of the illumination light source 10 and the wavelength tunable laser 30, and also controls the timing of OCT measurement and normal surface observation by controlling the signal capture timing of the CCD sensor 24. For example, MPU (Micro Processing Unit) is mentioned.

  The structure B includes a wavelength tunable laser 30, an optical fiber 31, a collimator 32, an optical path conversion member 33, and a reflection member 35 that are included only in the structure B, and the beam expanding unit 20 and the multiplexing / demultiplexing unit that are also included in the structure A described above. 21, a pair of lenses 22, an aperture 23, a CCD sensor 24, a memory 25, a calculation means 26, a display means 27, and a control means 28.

  The wavelength tunable laser 30 is a light source capable of emitting light of an arbitrary wavelength band within a predetermined range, and has a frequency width Δ at a measurement time T [s] at a scanning rate α “Hz / s” of the optical frequency. It scans over f (= αT) [Hz]. As this wavelength band, a wavelength band that is advantageous for an endoscope and less absorbed by moisture (for example, the center wavelength of near infrared light is 0.8 μm band, 1.3 μm band, or 1.6 μm band) is preferable, A wavelength band excellent in availability and relatively little absorption by moisture (for example, a central wavelength of 1.55 μm band) may be used.

  The optical fiber 31 is a member for guiding the light emitted from the wavelength tunable laser 30 to a collimator 32 to be described later, and examples thereof include a single mode optical fiber.

  The collimator 32 is a member for converting light emitted through the optical fiber 31 into substantially parallel light (collimated light), and examples thereof include a gradient index fiber (graded index fiber). A graded index fiber (graded index fiber) is a fiber having an approximately square refractive index distribution in its axial symmetry, and collimated light can be obtained by adjusting its length. By providing the refractive index distribution type fiber in this way, the beam diameter of the light emitted from the optical fiber 31 can be increased, so that the irradiation area (measurement area) of the light to the measurement target M can be widened. it can. The connection of the collimator 32 to one end of the optical fiber 31 is preferably performed by fusion in order to reduce light reflection and connection loss, but the connection method is not limited to this.

  The optical path changing member 33 is a member having a function of emitting light incident through the collimator 32 in a direction different from the incident direction (for example, a vertical direction), and is, for example, the side opposite to the side connected to the collimator 32. And a structure in which a reflection mirror is attached to the polished surface of the coreless fiber whose end is polished obliquely. This reflection mirror is formed by evaporating a noble metal (such as gold) or a dielectric multilayer film on the polished surface of the coreless fiber. The connection of the optical path conversion member 33 to one end of the collimator 32 is preferably performed by fusion in order to reduce light reflection and connection loss, but the connection method is not limited to this. Further, the connection between the optical path conversion member 33 and the multiplexing / demultiplexing means 21 is performed from the optical path conversion member 33 by using an adhesive 34 (for example, an epoxy thermosetting resin or an acrylic ultraviolet curing resin) having high refractive index matching. This is performed by adhering and fixing the emitted light (collimated light) so that the light enters the light incident portion of the multiplexing / demultiplexing means 21 at a substantially right angle.

  The reflection member 35 is a member for reflecting the reference light demultiplexed by the multiplexing / demultiplexing means 21, and is formed by evaporating metal (such as aluminum) on a predetermined portion of the multiplexing / demultiplexing means 21, for example.

  The optical tomographic imaging apparatus X according to this embodiment includes a multiplexing / demultiplexing unit 21 and a CCD sensor 24. The multiplexing / demultiplexing means 21 has a function of transmitting reflected light when the illumination light emitted from the illumination light source 10 is irradiated to the irradiated portion L, and the CCD sensor 24 interferes with the reflected light. It also has a function of receiving light (the combined light of the reflected measurement light and the reflected reference light). Therefore, the optical tomographic imaging apparatus X does not secure a region through which the irradiation light (or reflected light) passes separately from the region through which the measurement light (or reflected measurement light) and the reference light (or reflected reference light) pass. In addition to this, it is not necessary to provide a CCD sensor for receiving irradiation light (or reflected light) separately from the CCD sensor 24 for receiving measurement light (or reflected measurement light) and reference light (or reflected reference light). Therefore, in the optical tomographic imaging apparatus X, it is possible to reduce the size of the part (tip portion) that emits the measurement light and the irradiation light, and also to reduce the number of parts, thereby reducing the cost. It can be done.

  The multiplexing / demultiplexing means 21 of the optical tomographic imaging apparatus X includes a pair of triangular prisms 21a and 21b constituting a rectangular parallelepiped, and a dielectric multilayer film 21c formed on the opposing surfaces of the pair of prisms 21a and 21b. Become. For this reason, the optical tomographic imaging apparatus X has a large light transmission characteristic with respect to the wavelength band (for example, the visible light region) of the illumination light source 10, and therefore the CCD sensor 24 can more efficiently receive the reflected light from the irradiated portion L. it can.

  The optical tomographic imaging apparatus X includes a light guide 11, an optical fiber 31, and a collimator 32. Therefore, the optical tomographic imaging apparatus X can appropriately emit the measurement light and the irradiation light without arranging the illumination light source 10 and the wavelength tunable laser 30 in the vicinity of the part that emits the measurement light and the irradiation light. Since the light guide 11 and the optical fiber 31 are usually smaller in size than the illumination light source 10 and the wavelength tunable laser 30, the optical tomographic imaging apparatus X can reduce the size of the portion that emits measurement light and irradiation light. Moreover, since the light emitted through the optical fiber 32 by the collimator 32 can be converted into substantially parallel light, the emitted light can be widened to enlarge the measurement area.

  In the optical tomographic imaging apparatus X, when the wavelength band of the illumination light emitted from the illumination light source 10 is a visible light region, the light emitted from the illumination light source 10 can be used as a guide light for illuminating the irradiated portion L. Therefore, it is possible to appropriately move the portion from which the measurement light or the irradiation light is emitted to the target position.

  In this optical tomographic imaging apparatus X, when the wavelength band of the light emitted from the wavelength tunable laser 30 is in the near-infrared light region, the measurement light irradiated to the measurement target M reaches, for example, the inside of the living body. Therefore, a tomographic image inside the living body can be obtained.

  The optical tomographic imaging apparatus X includes a wavelength tunable laser 30 as a light source for measurement. For this reason, in the optical tomographic imaging apparatus X, interference light formed by combining the reflected measurement light and the reflected reference light can be obtained by changing the wavelength of the light emitted from the wavelength tunable laser 30, so that the movable mechanism member can be obtained. It is not necessary to arrange a flexible shaft (for example, a flexible shaft for scanning measurement light emitted from a prism) in the vicinity of a portion from which measurement light or irradiation light is emitted. Therefore, the optical tomographic imaging apparatus X can be downsized in the vicinity of a portion that emits measurement light and irradiation light. Further, the optical tomographic imaging apparatus X can avoid the occurrence of noise in the measurement signal due to the vibration, in addition to avoiding the vibration caused by the movement of the movable mechanism member with respect to the measurement target. .

  Hereinafter, an example of the operation of the optical tomographic imaging apparatus X will be described. First, illumination light is emitted from the illumination light source 10 under the control of the control means 28. Next, the irradiated portion L is irradiated with the illumination light emitted from the illumination light source 10 through the light guide 11 and the illumination lens. Next, the reflected light from the irradiated portion L is received by the CCD sensor 24 through the beam expanding means 20, the multiplexing / demultiplexing means 21, the pair of lenses 22, and the aperture 23. Next, the light received by the CCD sensor 24 is converted into a signal and recorded in the memory 25. Next, the signal recorded in the memory 25 is calculated by the calculation means 26, and based on the result, the display means 27 displays the image of the irradiated portion L. Then, while referring to this image, the part of the optical tomographic imaging apparatus X that emits the measurement light is moved to the target position. Next, under the control of the control unit 28, the emission of illumination light from the illumination light source 10 is stopped, and light in a predetermined wavelength region (visible light region) is emitted from the wavelength tunable laser 30. Next, the light emitted from the wavelength tunable laser 30 is guided to the multiplexing / demultiplexing member 21 through the optical fiber 31, the collimator 32, and the optical path conversion member 33. Next, the light guided to the multiplexing / demultiplexing member 21 is demultiplexed into the measuring light irradiated toward the measurement target M and the reference light irradiated toward the reflecting member 35 by the dielectric multilayer film 21c. The Next, the reflected measurement light from the measurement target M is introduced into the multiplexing / demultiplexing means 21 via the beam expanding means 20, and the reflected reference light from the reflecting member 35 is introduced into the multiplexing / demultiplexing means 21. Interfering light by wave. Next, the interference light derived from the multiplexing / demultiplexing means 21 is received by the CCD sensor 24 via the pair of lenses 22 and the aperture 23. Next, the light received by the CCD sensor 24 is converted into a signal and recorded in the memory 25. Next, the signal recorded in the memory 25 is calculated by the calculation means 26, and a three-dimensional image (or two-dimensional image) is displayed on the display means 27 based on the result.

Here, the calculation method in the calculation means 26 will be briefly described. First, the portion to be measured M is located at a position where the length from the facing surface of the pair of triangular prisms 21a and 21b to the portion to be measured M in the multiplexing / demultiplexing means 21 is equal to the length from the facing surface to the reflecting member 35. And the case where a reflective surface exists only in the position of the depth z from the surface of this to-be-measured part M is demonstrated. Assuming that the frequency of the light emitted from the wavelength tunable laser 30 is changed over the frequency width Δf [Hz] (= αT) during the measurement time T [s] at the scanning rate α [Hz / s], the object light delay time of τ (= 2nz / c), and the interference light varies the beat frequency _{f b.} The beat frequency f _b is represented by formula "number 1" shown below. Accordingly, selectively eject the interference signal modulated at the beat frequency f _b, becomes possible to detect the reflected light signal from a certain depth z.

Further, the intensity of the reflected reference light to be introduced into the CCD sensor 24 and I _r, the intensity of the interference light when the intensity of the reflected measuring beam and the I _o I (t) is a formula shown in the following "Formula 2" expressed.

The CCD sensor 24, the interference light sensed over a frame time _{T f,} and outputs a signal (video signal) for each frame time _{T f.} Here, the frequency of the wavelength tunable laser 30 is changed, and data of a large number of frames (M) is acquired continuously within one variable period of the frequency. When the power spectrum is obtained by digital Fourier transforming M acquired data for each pixel, the beat frequency can be detected and the reflection position can be derived. Incidentally, since the digital Fourier transformed spectrum frequency interval is 1 / T, the distance resolution [delta] _z is expressed by Equation shown in the following "Expression 3".

When the optical path length of the measurement light and the optical path length of the reference light are different, there is an offset a in the optical path length of the measurement light and the optical path length of the reference light in the above “Equation 1” (that is, the measurement optical path length is only a. If the refractive index is 1 in the air, the range of the offset a is expressed by the following equation (4). Comparing the equation shown in “Equation 4” with the equation shown in “Equation 1”, the beat frequency f _{b in the} equation shown in “Equation 4” is larger than the beat frequency f _{b in the} equation shown in “Equation 1”. I understand. Thus, the beat frequency f _b is increased, because that leads to increasing the sampling frequency required when digital Fourier transform, although the number of sampling frames increases, different from the measurement light optical path length of the reference light of However, it is possible to calculate.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The optical tomographic imaging apparatus X may include an image fiber (image transmission fiber) formed by bundling a plurality of optical fibers between the multiplexing / demultiplexing unit 21 and the CCD sensor 24. According to such a configuration, the interference light multiplexed by the multiplexing / demultiplexing means 21 can appropriately reach the CCD sensor 24 without arranging the CCD sensor 24 in the vicinity of the multiplexing / demultiplexing means 21. Since such an image fiber is usually smaller in size than the CCD sensor 24, the optical tomographic imaging apparatus of this configuration can be downsized in the vicinity of the multiplexing / demultiplexing means 21.

It is a principal part expansion perspective view showing schematic structure of the optical tomographic imaging apparatus X which concerns on this invention. It is a principal part enlarged view of the optical tomographic imaging apparatus X shown in FIG. 1, (a) is one side view, (b) is another side view. It is a figure showing schematic structure of the conventional endoscope.

Explanation of symbols

X optical tomography apparatus L irradiated part M measured part 10 illumination light source (first light source)
DESCRIPTION OF SYMBOLS 11 Light guide 12 Illumination lens 20 Beam expansion means 21 Multiplexing / demultiplexing means 22 Pair of lenses 23 Aperture 24 CCD sensor (light receiving element)
25 Memory 26 Calculation means 27 Display means 28 Control means 30 Wavelength variable laser (second light source)
31 Optical fiber 32 Collimator 33 Optical path conversion member 34 Adhesive 35 Reflective member

Claims (7)

A first light source that emits light having a wavelength in a first wavelength band;
A second light source that emits light having a wavelength in a second wavelength band different from the first wavelength band;
Measurement that transmits reflected light when the light emitted from the first light source irradiates the irradiated portion L and irradiates the measured portion with the light emitted from the second light source. The light and the reference light irradiated to the reflecting member are demultiplexed, and the reflected measuring light and the reference light are irradiated to the reflecting member when the measuring light is irradiated to the measured part. Multiplexing / demultiplexing means for multiplexing the reflected reference light at the time,
An optical tomographic imaging apparatus comprising: a light receiving element that receives the reflected light and receives interference light formed by combining the reflected measurement light and the reflected reference light. 2. The optical tomographic imaging apparatus according to claim 1, wherein the multiplexing / demultiplexing unit includes a pair of triangular prisms constituting a rectangular parallelepiped, and a dielectric multilayer film formed on opposing surfaces of the pair of prisms. . A first light guide member for guiding light emitted from the first light source, a second light guide member for guiding light emitted from the second light source, and the combined wave of the second light guide member The optical tomographic imaging apparatus according to claim 1, further comprising: a collimator connected to an end portion on the means side and configured to convert light emitted from the second light guide member into substantially parallel light. 4. The optical tomographic imaging according to claim 1, further comprising an image fiber formed by bundling a plurality of optical fibers between the multiplexing / demultiplexing unit and the light receiving element. 5. The optical tomographic imaging apparatus according to claim 1, wherein the first wavelength band is a visible light wavelength band. The optical tomographic imaging apparatus according to claim 1, wherein the second wavelength band is a wavelength band of near infrared light. The optical tomographic imaging apparatus according to claim 1, wherein the second light source is a wavelength tunable laser having a wavelength conversion function in the second wavelength band.

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