JP5366718B2 - Scanning medical probe and medical observation system - Google Patents

Description

  The present invention relates to a medical observation system that scans a subject and generates an observation image, and a scanning medical probe provided in the medical observation system, and more specifically, resonates the tip of an ultrafine optical fiber. The present invention relates to a scanning medical probe that optically scans an object and a medical observation system that generates an observation image of the optically scanned object.

  A fiberscope and an electronic scope are generally known as medical devices used when an operator diagnoses a body cavity of a patient. For example, an operator who uses an electronic scope inserts the insertion portion of the electronic scope into a body cavity and guides the insertion distal end portion provided at the distal end of the insertion portion to the vicinity of the subject. The surgeon operates the operation unit of the electronic scope or the video processor as necessary, and illuminates the subject with the illumination light emitted from the light source device. The surgeon images the reflected light image of the illuminated subject with a solid-state imaging device such as a CCD (Charge Coupled Device) mounted on the insertion tip. The surgeon observes the captured image of the subject through a monitor and performs diagnosis and treatment.

  The insertion tip of this type of electronic scope is constantly required to be small in size so that it can be smoothly inserted into a patient's body cavity or a minute gap. However, the mounting component at the insertion tip includes, for example, a component having a large size such as a solid-state imaging device. The smallest external dimensions possible for the design of the insertion tip are substantially defined by such large parts. Therefore, in order to reduce the diameter of the insertion tip, it is desired to select a solid-state imaging device or the like that is further downsized. However, for example, as a solid-state imaging device is generally smaller, performance relating to resolution, dynamic range, SN ratio, and the like is lowered. For this reason, even when it is desired to reduce the diameter of the insertion tip, a small solid-state image sensor cannot be easily selected.

  Therefore, a scanning medical probe that can be made smaller in diameter than a conventional electronic scope (that is, an electronic scope equipped with a solid-state image sensor) by adopting a configuration that eliminates the need for the solid-state image sensor itself is proposed. Has been. A specific configuration example of a medical observation system having this type of scanning medical probe is described in Patent Document 1. The scanning medical probe described in Patent Document 1 resonates the tip of a single optical fiber (generally, a single mode fiber) and scans a subject with a predetermined scanning pattern with predetermined scanning light. The scanning medical probe detects reflected light from a subject, performs photoelectric conversion, and sequentially outputs it to a video processor. The video processor processes the photoelectrically converted signal, images it, and outputs it to the monitor. The surgeon can observe the image in the body cavity obtained in this way through a monitor in the same manner as when using an electronic scope, and perform diagnosis, treatment, and the like.

International Publication No. 2007/084915 Pamphlet

  In general, the scanning medical probe is configured such that the vicinity of the base of the insertion tip can be bent by remote operation by a hand operation unit. When the vicinity of the root of the insertion tip is bent and the direction of the insertion tip changes, the imaging range of the scanning medical probe moves. The single mode fiber that emits the scanning light is bent at a location near the base of the insertion tip during a bending operation by remote control.

  However, the single-mode fiber of a scanning medical probe has a smaller core diameter than a light guide (multi-mode fiber bundle) of a general electronic scope. Leakage is likely to occur. Specifically, when a single mode fiber is bent so that its radius of curvature (bending radius) gradually decreases, the amount of light loss at the bent portion increases exponentially at a certain bending radius. Have. The amount of light loss due to bending is wavelength-dependent, and the bending radius at which the amount of lost light begins to increase exponentially as the wavelength of the longer wavelength increases. When scanning light having a plurality of types of wavelengths is used, depending on the bending radius, only the scanning light on the long wavelength side may be greatly lost. In this case, a problem is pointed out that an image with low color reproducibility in which only a part of colors corresponding to scanning light having a wavelength with a large loss is lost is captured.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a scanning medical probe suitable for avoiding deterioration (fluctuation) in color reproducibility of a captured image associated with a bending operation, and It is to provide a medical observation system.

  A scanning medical probe according to an embodiment of the present invention that solves the above-described problems is an optical fiber that transmits light having a specific wavelength emitted from a light source and emits the light from an emission end, and bends a specific portion of the optical fiber. A bending means, a fiber Bragg grating that reflects a part of light of a specific wavelength, formed at a specific location of the optical fiber, and an optical fiber so that light of a specific wavelength emitted from the emission end is scanned on the subject And a reflected light output means for outputting reflected light from the scanned subject to a predetermined detector. The fiber Bragg grating keeps the amount of light emitted from the exit end of the optical fiber constant, thereby avoiding deterioration (fluctuation) in the color reproducibility of the captured image associated with the bending operation of the optical fiber. According to the present invention, the light loss amount of the light having the specific wavelength is compensated by the increase in the light transmission amount due to the increase in the transmittance due to the bending of the fiber Bragg grating with respect to the light of the specific wavelength.

  The light emitted from the light source may include light of a plurality of types of wavelengths including light of a specific wavelength. In this case, light of a specific wavelength is emitted from the emission end of the light of another type in order to avoid the balance with other colors being lost due to reflection of the fiber Bragg grating. The amount of light emitted from the light source is larger than that of the other types of wavelengths so as to be equal to the amount of light. The specific wavelength light is, for example, the longest wavelength light among a plurality of types of wavelengths.

  The optical fiber is, for example, a single mode fiber coupled with a light source.

  A medical observation system according to an embodiment of the present invention that solves the above-described problem is output from a scanning medical probe and a light source that emits light of a specific wavelength to the scanning medical probe according to any of the above. A detector that receives reflected light from the subject and detects an image signal; and a pixel arrangement determination unit that determines a pixel arrangement of image information represented by each image signal based on detection timing of the image signal; An image creation means for creating an image by spatially arranging each piece of image information in accordance with the determined pixel arrangement.

  The light source may be configured to emit light of a plurality of types of wavelengths including light of a specific wavelength. In this case, light of a specific wavelength is emitted from the emission end of the light of another type in order to avoid the balance with other colors being lost due to reflection of the fiber Bragg grating. The amount of light emitted from the light source is larger than that of the other types of wavelengths so as to be equal to the amount of light.

  ADVANTAGE OF THE INVENTION According to this invention, the scanning medical probe suitable for avoiding the deterioration (fluctuation) of the color reproducibility of the picked-up image accompanying bending operation | movement and a medical observation system are provided.

It is a figure showing roughly composition of a medical observation system of an embodiment of the present invention. It is a block diagram which shows the structure of the processor of embodiment of this invention. It is a sectional side view which shows the typical internal structure of the insertion flexible part front-end | tip of the scanning medical probe of embodiment of this invention. It is a sectional side view which shows the typical internal structure of the insertion flexible part front-end | tip of the scanning medical probe of embodiment of this invention. It is a figure which shows the relationship between the reflection spectrum of the fiber Bragg grating of embodiment of this invention, and R pulse light. It is a figure for demonstrating the spot formed on a to-be-photographed object. It is a figure for demonstrating the relationship between the image information detected in the timing T, and a pixel address. It is a figure for demonstrating the conventional problem. It is a figure which shows the light quantity characteristic in embodiment of this invention.

  Hereinafter, a medical observation system according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram schematically showing a configuration of a medical observation system 1 of the present embodiment. As shown in FIG. 1, the medical observation system 1 has a scanning medical probe 100. The scanning medical probe 100 has an insertion flexible portion 130 that is sheathed by a flexible outer sheath 132. The surgeon directly inserts the insertion flexible portion 130 into the patient's body cavity from the distal end (hereinafter referred to as “insertion flexible portion distal end 130a”), and guides the insertion flexible portion distal end 130a to the vicinity of the subject. Alternatively, in order to smoothly guide the insertion flexible portion distal end 130a to the vicinity of the subject, the insertion flexible portion 130 is inserted into the body cavity with a guide wire or the like. Alternatively, for example, the insertion flexible portion 130 is inserted through a forceps channel of a general electronic scope on which a solid-state imaging device is mounted, and the insertion flexible portion distal end 130a is operated close to the subject.

  A proximal operation portion 150 for operating the scanning medical probe 100 is provided at the proximal end of the insertion flexible portion 130. The vicinity of the root of the insertion flexible portion distal end 130 a is configured to be bent by remote operation by the hand operation portion 150. When the vicinity of the base of the insertion flexible portion distal end 130a is bent and the direction of the insertion flexible portion distal end 130a is changed, the imaging range by the scanning medical probe 100 is moved. A connector part 110 is provided at the base end of the universal cable 160 extending from the hand operation part 150.

  The bending mechanism incorporated in the scanning medical probe 100 is the same as the bending mechanism of a general electronic scope, and the distal end of the insertion flexible portion is pulled by pulling the operation wire in conjunction with the operation of the hand operation portion 150. It is configured to bend the vicinity of the root of 130a. The bending mechanism of the scanning medical probe 100 is not shown in each drawing for the sake of simplicity.

  The medical observation system 1 has a processor 200. The processor 200 drives and controls the scanning medical probe 100 and generates an image signal based on the observation light acquired by the scanning medical probe 100, and the scanning medical probe in a body cavity where natural light does not reach. The integrated processor includes a light source device that emits scanning light through the probe 100. In another embodiment, the signal processing device and the light source device may be configured separately. The processor 200 has a connector part 210. When the connector part 110 is inserted into the connector part 210, the scanning medical probe 100 and the processor 200 are optically and electrically connected.

  FIG. 2 is a block diagram illustrating a configuration of the processor 200. In FIG. 2, in order to clarify the connection relationship between the scanning medical probe 100 and the processor 200, the configuration of the connector unit 110 is also schematically shown.

  The processor 200 includes laser light sources 230R, 230G, and 230B that oscillate light corresponding to R, G, and B wavelengths as light sources for scanning the subject. The light source is not limited to the laser light source, and may be another type of light source such as an LED (Light Emitting Diode).

  The processor 200 has a timing controller 240 that comprehensively controls the signal processing timing of each circuit of the processor 200. The timing controller 240 outputs a predetermined modulation control signal to each driver circuit of the light source drivers 232R, 232G, and 232B. The light source drivers 232R, 232G, and 232B directly modulate the laser light sources 230R, 230G, and 230B, respectively, according to the input modulation control signal. Specifically, each driver circuit passes a current of the same phase with a predetermined amplitude to the corresponding laser light source in accordance with the modulation control signal. The laser light sources 230G and 230B are pulsed light having the same intensity (light quantity) corresponding to G and B wavelengths (hereinafter referred to as “G pulsed light” and “B pulsed light”), and the laser light source 230R is G Pulse light corresponding to the wavelength of R (hereinafter referred to as “R pulse light”) having an intensity (light quantity) approximately twice that of pulse light or B pulse light is oscillated at synchronized timings.

  The R pulse light, G pulse light, and B pulse light oscillated from each laser light source enter the optical coupler 234. The optical coupler 234 combines and emits each incident pulsed light in a state where the phases are aligned. Hereinafter, for convenience of description, the pulsed light combined by the optical coupler 234 is referred to as “coupled pulsed light”.

  The combined pulse light emitted from the optical coupler 234 enters the incident end 112a of the single mode fiber 112 included in the scanning medical probe 100. The single mode fiber 112 is accommodated in the insertion flexible portion 130 from the connector portion 110 to the insertion flexible portion distal end 130a. The coupled pulsed light incident on the incident end 112a propagates by repeating total reflection inside the single mode fiber 112.

  3 and 4 are side sectional views showing a schematic internal structure of the insertion flexible portion distal end 130a. Hereinafter, in describing the configuration of the scanning medical probe 100, for convenience, the longitudinal direction of the scanning medical probe 100 is defined as the Z direction, and the two directions orthogonal to the Z direction and orthogonal to each other are defined as the X direction and the Y direction. Define. According to this definition, for example, FIG. 3 is a cross-sectional view of the insertion flexible portion distal end 130 a in the YZ plane including the central axis AX of the scanning medical probe 100.

  As shown in FIG. 1, FIG. 3, etc., the outer diameter of the insertion flexible portion 130 that is the insertion portion of the scanning medical probe 100 is defined by the outer sheath 132. The outer sheath 132 has a configuration in which the scanning medical probe 100 is not mounted with a solid-state imaging device, and thus is significantly thinner than the outer diameter of a general electronic scope. Therefore, the scanning medical probe 100 achieves a much lower invasive property than a general electronic scope.

  As shown in FIG. 3, an inner sheath 134 having an outer diameter smaller than that of the outer sheath 132 is coaxially disposed inside the outer sheath 132. In an annular space defined by the inner wall of the outer sheath 132 and the outer wall of the inner sheath 134, a plurality of detection fibers 136 are uniformly arranged over the entire circumference. The plurality of detection fibers 136 are bundled at the end side inside the connector unit 110, and constitute a single optical fiber bundle 136B.

  A support body 138 is provided inside the inner sheath 134. The tip 112c of the single mode fiber 112 is inserted through the through hole of the support 138 and supported in a cantilever state. A biaxial (X-axis and Y-axis) piezoelectric actuator 140 supported by a support 138 is bonded to the base of the distal end portion 112c. The piezoelectric actuator 140 has a pair of X-axis electrodes and a pair of Y-axis electrodes formed on a piezoelectric body. The ends of each X-axis electrode and each Y-axis electrode are connected to electric wires (not shown) accommodated in the connector portion 110. When the connector part 110 and the connector part 210 are connected, the piezoelectric actuator 140 is connected to the X-axis driver 236X and the Y-axis driver 236Y of the processor 200 via electric wires.

  The timing controller 240 outputs predetermined drive control signals to the driver circuits of the X-axis driver 236X and the Y-axis driver 236Y. The X-axis driver 236X applies an AC voltage X between the X-axis electrodes of the piezoelectric actuator 140 in accordance with the drive control signal to resonate the piezoelectric body in the X direction. In accordance with the drive control signal, the Y-axis driver 236Y applies an AC voltage Y having the same frequency as the AC voltage X and orthogonal in phase to the Y-axis electrode of the piezoelectric actuator 140 to resonate the piezoelectric body in the Y direction. . The AC voltages X and Y are respectively defined as voltages that gradually increase at a constant rate and reach effective values (X) and (Y) over time (X) and (Y).

  As shown in FIG. 4, the single mode fiber 112 bends at a location near the base of the insertion flexible portion distal end 130 a when the scanning medical probe 100 is bent by remote operation of the hand operation portion 150. A fiber Bragg grating FBG that causes strong back reflection of the R component is formed in the core at this location.

  FIG. 5 is a diagram showing the relationship between the reflection spectrum of the fiber Bragg grating FBG and the R pulse light (wavelength: 638 nm). The horizontal axis in FIG. 5 indicates the wavelength (unit: nm), and the vertical axis in FIG. 5 indicates the reflectance (unit:%). In FIG. 5, symbol R1 indicates the reflection spectrum of the fiber Bragg grating FBG when the single mode fiber 112 is not bent (see FIG. 3). As shown in FIG. 5, the reflectance of the fiber Bragg grating FBG with respect to the R pulse light is about 40% (˜50%) when the single mode fiber 112 is not bent. For this reason, the R pulse light is cut by about half the amount of light by the fiber Bragg grating FBG. Therefore, the combined pulsed light emitted from the emission end 112b of the single mode fiber 112 has the same intensity (light quantity) of components of R, G, and B wavelengths.

  The exit end 112b of the single mode fiber 112 is a surface that approximates the XY plane by combining the kinetic energy in the X and Y directions by the piezoelectric actuator 140 (hereinafter referred to as “XY approximate surface”). It rotates so that a spiral pattern may be drawn around the central axis AX. The rotation trajectory of the injection end 112b becomes larger in proportion to the applied voltage, and draws a trajectory of a circle having the largest diameter when the AC voltage having the effective values (X) and (Y) is applied.

  The coupled pulsed light is emitted from the emission end 112b of the single mode fiber 112 during the period from the start of application of AC voltage to the piezoelectric actuator 140 until the application is stopped (that is, the period corresponding to time (X) or (Y)). to continue. Hereinafter, for convenience of explanation, this period is referred to as a “sampling period”.

  After the elapse of the sampling period, the application of the AC voltage to the piezoelectric actuator 140 is stopped, and the vibration of the tip 112c of the single mode fiber 112 is attenuated. The circular motion of the exit end 112b on the XY approximate plane converges with the vibration attenuation of the tip 112c of the single mode fiber 112, and stops on the central axis AX after a predetermined time. Hereinafter, for convenience of explanation, the period from the end of the sampling period to the stop of the injection end 112b on the central axis AX (more precisely, the calculation required to stop to guarantee the stop on the central axis AX) A period slightly longer than the above time) is referred to as a “braking period”. A period corresponding to one frame includes a sampling period and a braking period. In order to shorten the braking period, a reverse phase voltage may be applied to the piezoelectric actuator 140 in the initial stage of the braking period to actively apply the braking torque.

  A condensing optical system 142 is disposed in front of the exit end 112 b of the single mode fiber 112. The combined pulse light emitted from the emission end 112b is condensed by the condensing optical system 142 to form a spot Si on the subject. The spot diameter is extremely small, for example, on the order of several microns.

FIG. 6 is a diagram for explaining the spots Si (i = 1 to n) formed on the subject. In order to obtain one image, the scanning medical probe 100 divides n spots Si into spots S ₁ , S ₂ , S ₃ ,... So as to draw a spiral pattern SP on the subject during one sampling period. , formed in this order _{S n-2, S n-} 1, S n. The interval between the spots Si is determined depending on the motion speed of the exit end 112b of the single mode fiber 112, the modulation frequency of each laser light source, and the like. The spiral pattern SP is a virtual scanning locus drawn on the assumption that continuous light is scanned on the subject instead of pulsed light.

  The position (trajectory) of the exit end 112b of the single mode fiber 112 on the XY approximate plane during the sampling period is obtained in advance as a result of repeated experiments. Further, the relationship between the position of the emission end 112b and the position in the imaging range (scanning range) where the spot Si will be formed on the subject when the combined pulse light is emitted at each position is also calculated in advance. Yes. Furthermore, the relationship between the spot formation position within the imaging range and the pixel position when imaging by detecting the reflected pulse light from each spot formation position is also calculated in advance. Based on the known information, the timing controller 240 controls the X-axis driver 236X and the Y-axis driver 236Y (that is, controls the AC voltage applied to the piezoelectric actuator 140) and controls the light source drivers 232R, 232G, and 232B. Each of (that is, modulation control of each laser light source during the sampling period) is repeated at a cycle according to the frame rate.

  The reflected pulse light of the light that forms the spot Si on the subject enters the incident end 136a of the detection fiber 136. The reflected pulsed light incident on the incident end 136a propagates by repeating total reflection inside the detection fiber 136. An exit end 136b of the detection fiber 136 (optical fiber bundle 136B) is coupled to the optical separator 238 of the processor 200 via a connecting portion between the connector part 110 and the connector part 210.

  The optical fiber bundle 136B is merely a bundle of about several tens (for example, 80) of detection fibers 136. Therefore, the optical fiber bundle 136B has a much smaller diameter than an optical fiber bundle of a general electronic scope or fiberscope (for example, an optical fiber bundle in which several hundred to thousands of optical fibers are bundled). In this embodiment, at least one detection fiber 136 is required. When the number of detection fibers 136 is one, the diameter of the scanning medical probe 100 can be further reduced.

  The optical separator 238 separates the reflected pulsed light from the optical fiber bundle 136B into reflected pulsed light of R, G, and B wavelengths, and outputs them to the photodetectors 250R, 250G, and 250B.

  As described above, the combined pulse light is guided by the single single mode fiber 112 and irradiates the subject. Therefore, the amount of reflected pulse light reflected on the subject is very small. In order to detect such weak light reliably and with low noise, a high-sensitivity photodetector such as a photomultiplier tube is employed for each photodetector of the photodetectors 250R, 250G, and 250B.

  The photodetectors 250R, 250G, and 250B photoelectrically convert the received reflected pulse light of each wavelength to generate an analog signal, and output the analog signal to a subsequent circuit. The analog signal corresponding to the reflected pulse light of each wavelength is sampled and held, and converted into a digital signal sequence by the A / D converters 252R, 252G, and 252B. The converted digital signal sequence is input to a DSP (Digital Signal Processor) 254.

  The DSP 254 is created based on the above-described known information, based on the position in the imaging range where the spot Si of the combined pulse light is formed (the address of the pixel constituting the image according to another aspect), and each spot Si. A conversion table that associates the timing T when the reflected pulsed light is detected is held. The DSP 254 monitors the digital signal sequence from each A / D converter while referring to the conversion table, and converts the signal corresponding to each wavelength at each timing T to the image signal (that is, the A / D converter 252R) at each pixel address. From the A / D converter 252G is detected as a G-color luminance value, and a signal from the A / D converter 252B is detected as a B-color luminance value). The DSP 254 buffers the detected image signal of each pixel address in the frame memory FM.

The relationship between the image signal detected at each timing T and the pixel address will be specifically described with reference to FIG. Here, for convenience of explanation, it is assumed that the finally generated image is composed of a 19 × 19 pixel arrangement. The DSP 254 refers to the conversion table and detects an image signal corresponding to each wavelength at the timing t ₁ corresponding to the spot S ₁ . The DSP 254 buffers the image signal corresponding to each detected wavelength in the frame memory FM in association with the pixel address (10, 10). The image signals corresponding to the respective wavelengths at the timings T ₂ , T _3, ... Corresponding to the subsequent spots S ₂ , S _3, ... Are sequentially detected, and the pixel addresses (9, 9), (9, 11) are detected. Are sequentially buffered in the frame memory FM in association with. Frame memory FM, the image signal of one frame (all pixels) corresponding to the spot _S 1 to S _n generated by DSP254 is buffered.

  The DSP 254 generates, for example, predetermined masking data for a pixel address that does not have an image signal corresponding to each wavelength, and buffers it in the frame memory FM. The DSP 254 reads out the image signal buffered in the frame memory FM and outputs it to the encoder 256 in accordance with the timing control by the timing controller 240.

  The encoder 256 converts the input image signal into a video signal conforming to a predetermined standard and outputs the video signal to the monitor 300. As a result, a color image of the subject consisting of R, G, and B colors is displayed on the monitor 300. The white balance, brightness, etc. of the image displayed on the monitor 300 can be adjusted by operating the operation panel 260.

  Here, in order to explain the conventional problems in FIG. 8, the light quantity of the R pulse light emitted from the exit end of the conventional single mode fiber (curve A in FIG. 8) and the light quantity loss of the R pulse light due to bending. The relationship with the rate (curve B in FIG. 8) is shown. The horizontal axis of FIG. 8 represents the bending radius (unit: mm) of the single mode fiber, and the vertical axis of FIG. 8 represents the amount of R pulse light emitted or the light loss rate (unit:%) due to bending. In FIG. 8, for the sake of convenience, the amount of light emitted from the R pulse light is expressed as 100% when there is no light loss due to bending, and the percentage decreases as the light loss increases. The bending radius of the horizontal axis becomes smaller toward the right side in FIG.

  As shown in FIG. 8, the amount of light emitted from the R pulse light increases exponentially with a bend radius (15 mm here) as a boundary (see curve B), and thus decreases sharply. (See curve A). When the emission light quantity of the R pulse light is significantly reduced, as described above, the photographed image has low color reproducibility with the R color missing. Also in this embodiment, when the scanning medical probe 100 is bent as shown in FIG. 4, light on the long wavelength side (that is, R pulse light) in the used wavelength is greatly lost, and color reproduction of the photographed image is performed. There is concern about the occurrence of problems that deteriorate the performance. However, the scanning medical probe 100 of the present embodiment is formed with the fiber Bragg grating FBG so as to avoid the deterioration of the color reproducibility of the captured image accompanying the bending operation.

  Since the detection fiber 136 is not as thin as the single mode fiber 112 (for example, a multimode fiber), no substantial light loss due to bending occurs at the bending radius within the movable range of the bending mechanism. Since the G pulse light and B pulse light also have short wavelengths, no substantial light loss due to bending occurs at the bending radius within the movable range of the bending mechanism. The single mode fiber 112 is gently bent along the shape of the esophagus, organ, etc., except at the bent portion by the bending mechanism. However, such a gentle curve does not cause a substantial light amount loss of the R pulse light.

In the fiber Bragg grating FBG, when the scanning medical probe 100 is bent as shown in FIG. 4, the pitch of the grating in which the high refractive index portions and the low refractive index portions are alternately arranged has a bending radius of the single mode fiber 112. It spreads according to. Here, the fiber Bragg grating FBG is the wavelength of light reflected lambda _{R (peak),} the pitch of the high refractive index portions and the low refractive index portion is defined as D, the effective refractive index of the grating portion is defined as n _e If, are those represented by the 2n _e × D, it is proportional to the pitch D. That is, the wavelength lambda _R, since the higher the pitch D is spread bend radius bent tightly single mode fiber 112 becomes smaller, it shifts to the long wavelength side. The shift of the reflection wavelength is indicated by reference numeral R2 in FIG. Reference symbol R2 indicates a reflection spectrum of the fiber Bragg grating FBG in a state where the single mode fiber 112 is bent (see FIG. 4). As shown in FIG. 5, the reflection spectrum of the fiber Bragg grating FBG shifts to the long wavelength side according to the bending of the single mode fiber 112.

  9 shows the same curve B as in FIG. 8, the ratio of the light amount of the R pulse light emitted from the exit end 112b of the single mode fiber 112 to the output (light amount) of the laser light source 230R (curve C in FIG. 9), It is a figure which shows the relationship between the reflectance (curve D of FIG. 9) and the transmittance | permeability (curve E of FIG. 9) of the fiber Bragg grating FBG with respect to R pulse light. The horizontal axis of FIG. 9 is the bending radius (unit: mm) of the single mode fiber, the vertical axis of FIG. 9 is the ratio of the emitted light amount to the output (light amount) of the laser light source 230R, the light loss rate due to bending, and the fiber Bragg grating. The reflectance and transmittance (unit:%) of the FBG are shown respectively. In FIG. 9, the bending radius of the horizontal axis becomes smaller toward the right side in FIG. 9, as in FIG. 8.

  As shown in FIG. 9, the reflectance of the fiber Bragg grating FBG with respect to the R pulse light is about 40% when the single mode fiber 112 is not bent (see curve D). The amount of light emitted from the R pulse light at this time is 60% of the transmittance of the fiber Bragg grating FBG with respect to the R pulse light (see curve E), and there is no substantial light amount loss due to bending (see curve B). The amount of light is 60% of the output (light amount) of the light source 230R (see curve C).

  When the single mode fiber 112 is further bent from a state where the bending radius is 15 mm or less, the reflection spectrum of the fiber Bragg grating FBG gradually shifts from R1 to R2 toward the long wavelength side (see FIG. 5). As the reflection spectrum shifts, the reflectance of the fiber Bragg grating FBG with respect to the R pulse light decreases and the transmittance increases (see curves D and E in FIG. 5). On the other hand, the amount of light loss due to bending increases exponentially (see curve B).

  Since the fiber Bragg grating FBG keeps the light emission amount of the R pulse light at a constant amount, the waveform of the reflection spectrum is compensated so that the light amount lost by the bending is compensated by the increase in the light transmission amount accompanying the increase in the transmittance of the fiber Bragg grating FBG. In addition, the shift amount is designed to match the light loss characteristic (curve B) corresponding to the bending radius. For this reason, the emitted light amount of the R pulse light is kept at 60% of the output (light amount) of the laser light source 230R as in the case of non-bending in spite of the loss of light amount due to bending (see curve B). (See curve C). In designing the fiber Bragg grating FBG, the light loss characteristic (curve B) corresponding to the bending radius of the single mode fiber 112 is calculated or measured in advance.

  That is, when the single mode fiber 112 is not bent, the transmittance of the R pulse light is suppressed by the fiber Bragg grating FBG, and the emission light amount of the R pulse light becomes equal to the emission light amount of the pulse light of other wavelengths. When the single mode fiber 112 is bent, the loss light amount of the R pulse light due to the bending is compensated by the increase in the transmitted light amount of the R pulse light in the fiber Bragg grating FBG, and the emission light amount of the R pulse light is emitted of the pulse light of other wavelengths. A state equal to the amount of light is maintained. Therefore, deterioration of the color reproducibility of the captured image due to the lack of R color can be effectively avoided. According to the configuration according to the present embodiment, for example, a simple configuration (fiber Bragg grating FBG is changed to a single mode fiber without complicated control of changing the output of the laser light source 230R according to the bending radius of the single mode fiber 112. 112), it is possible to compensate for the R-pulse light whose amount of light has been lost in real time.

  The above is the description of the embodiment of the present invention. The present invention is not limited to the above-described configuration, and various modifications can be made within the scope of the technical idea of the present invention. For example, when a loss of light amount due to bending also occurs in the G pulse light or B pulse light, a fiber Bragg grating corresponding to the G light or B light may be formed in the single mode fiber 112.

DESCRIPTION OF SYMBOLS 1 Medical observation system 100 Scanning type medical probe 150 Hand operation part 200 Processor 240 Timing controller 254 DSP
FBG fiber Bragg grating

Claims (6)

An optical fiber that transmits light of a specific wavelength emitted from a light source and emits the light from an emission end;
Bending means for bending a specific portion of the optical fiber;
A fiber Bragg grating that is formed at the specific location of the optical fiber and reflects a portion of the light of the specific wavelength;
Vibrating means for vibrating the vicinity of the emission end of the optical fiber so that the light of the specific wavelength emitted from the emission end is scanned on a subject;
Reflected light output means for outputting reflected light from the scanned subject to a predetermined detector;
Have
The fiber Bragg grating uses the fiber Bragg grating with respect to the light of the specific wavelength to reduce the light loss of the specific wavelength according to the bending of the specific location so that the amount of light emitted from the exit end is kept constant. A scanning medical probe characterized in that the scanning medical probe is formed to compensate for an increase in the amount of transmitted light due to an increase in transmittance due to the bending. The light emitted from the light source includes light of a plurality of types of wavelengths including light of the specific wavelength,
The light of the specific wavelength has a larger amount of light emitted from the light source than light of the other types of wavelengths so that the amount of light emitted from the emission end is equal to the amount of light emitted from the other ends of the light at the emission end. The scanning medical probe according to claim 1, wherein:   The scanning medical probe according to claim 2, wherein the light having the specific wavelength is light having a longest wavelength among the plurality of types of wavelengths.   4. The scanning medical probe according to claim 1, wherein the optical fiber is a single mode fiber coupled to the light source. 5. The scanning medical probe according to any one of claims 1 to 4 ,
A light source that emits light of a specific wavelength to the scanning medical probe ;
A detector that receives reflected light from a subject output from the scanning medical probe and detects an image signal;
Pixel arrangement determining means for determining a pixel arrangement of image information represented by each image signal based on the detection timing of the image signal;
Image creating means for spatially arranging the image information according to the determined pixel arrangement to create an image;
A medical observation system characterized by comprising: The light source emits light of a plurality of types of wavelengths including light of the specific wavelength,
The light of the specific wavelength has a larger amount of light emitted from the light source than light of the other types of wavelengths so that the amount of light emitted from the emission end is equal to the amount of light emitted from the other ends of the light at the emission end. The medical observation system according to claim 5, wherein:

Images