Patent Application
20130070255
The present invention relates to a technology for measuring optical tomographic images using an OCT (Optical Coherence Technology), to obtain an optical tomographic image.
In recent years, endoscopic devices for measuring the interior of a body cavity of a living subject are used in various fields, wherein while images of the living body are illuminated by illumination beam, said images are photographed due to a reflected beam coming from the living body, and the photographed images are displayed on a monitor. Further, most of the endoscopes include a forceps entrance for guiding a probe into the living body through a forceps channel, so that biopsy of tissues in the body cavity can be conducted for treatment of the patient.
As the above-detailed endoscopic devices, well-known is an ultrasonic tomographic image obtaining device using ultrasonic waves, while as another device, listed is an optical tomographic imaging device, which uses the optical interference by low coherence beam (see Patent Document 1). According to the optical tomographic imaging device cited in Patent Document 1, after the low coherent beams are emitted from a light beam source, said low coherent beam is divided into a measurement beam and a reference beam. The measurement beam is radiated onto a measurement subject, and a reflected beam from the measurement subject is guided to an optical multiplexing means. In order to change a measuring depth in the measurement subject, after an optical path length is changed, said reference beam is guided to the optical multiplexing means. The reflected beam and the reference beam are multiplexed by the optical multiplexing means, and interfering beam generated due to multiplexing is measured by heterodyne detection or the like.
Further, when the measurement beam is radiated onto the measurement subject, a probe is used, which is introduced into the body cavity from the forceps entrance of the endoscope through the forceps channel. The probe includes an optical fiber for guiding the measurement beam, and a mirror for reflecting the measurement beam at a right angle or a flat plate through which the measurement beam is transmissive, which are arranged on a top of the optical fiber. Through said probe, the measurement beam is radiated onto the measurement subject in the body cavity, and the reflected beam from the measurement subject is again guided to the optical multiplexing means through the optical fiber of the probe. At this time, a technology is used in which coherent beams can be detected, when the optical path lengths of the measurement beam and the reflected beam, and the optical path length of the reference beam are equal to each other. That is, the optical path length of the reference beam is changed so that a measuring position (being a measuring depth) against the measurement subject can be changed. This is called as an OCT measurement.
However, there is a problem on the optical tomographic imaging device. That is, when the probe is introduced into the living cavity of a living subject, precise positional relationships between a tissue and the probe cannot be obtained. If the precise positional relationships between the tissue and the probe cannot be obtained, a precise optical path length of the reference beam cannot be determined, so that the tissue tends to go out from a measurable scope, whereby it is not possible for the device to obtain a tomographic image of said tissue. To overcome this problem, it may be possible that while referring to the prior art in Patent Document 1, a window section is arranged on an external cylinder of the probe, whereby the optical beam path length of the reference beam is determined by the reflected beam from a window section. However, since the amount of the reflected beam coming from the window section cannot be adjusted, when the reflected beam is detected with the beam coming from the tissue of the living subject, noises will be generated, or confusion with the tomographic image will be generated. Further, since a prism is rotated to reflect the measurement beam, the distance between the window section and the prism is changed, whereby a problem occurs that the optical path length of the reference beam cannot be precisely adjusted.
The present invention has been achieved to solve the above problems, and an object of the present invention is to offer a probe of the optical tomographic image measuring device which can easily detect an optical tomographic image and control confusion with the noise, and to offer a method for adjusting said probe.
A probe for an optical tomographic image measurement device described in Claim 1, wherein the optical tomographic image measurement device includes a main body for obtaining an optical tomographic image of a measurement subject, and the probe for guiding measurement beams to the measurement subject, the optical tomographic image measurement device further includes: a light beam source for emitting low coherent beams; a light beam dividing means for dividing the low coherent beams emitted from the light beam source into measurement beams and reference beams; a reflection mirror for reflecting the reference beams divided by the light beam dividing means, and for giving a predetermined optical path length to the reference beams; an optical multiplexing means for multiplexing measured reflected beams returning from the measurement subject at a time when the measurement beams from the probe are radiated onto the measurement subject, and the reference beams reflected by the reflection mirror, and an optical interfering beam detection means for detecting optical interfering beams which are interfered with the measured reflected beams multiplexed by the optical multiplexing means and the reference beams, wherein the probe is characterized by a partially reflecting surface for reflecting some of the measurement beams at a position of a fixed measurement optical path length, and directing said some of the measurement beams to the optical multiplexing means.
According to the present invention, since the probe includes the partially reflecting surface for reflecting a part of the measurement beams at the position of the fixed optical path length which has been fixed, an optical path length to the partially reflecting surface can be fixed, whereby the optical path length of the reference beam is adapted to this length, and image signals based on the reflected light from the partially reflecting surface on the optical tomographic image can be precisely detected. Further, when the probe is introduced into the body cavity of a living subject, images, which are based on the reflected beam coming from the partially reflecting surface, are used so that images, which are based on the reflected beams from the tissue of the living subject, can be easily determined. “The partially reflecting surface” includes a reflection surface (which is a half mirror, for example) to make some of incident beams to be transmissive and to reflect the remaining incident beams at the same area, and a reflection surface to make incident beams to be transmissive at a part of an area of the reflection surface, and to reflect the incident beams at the remaining area of the reflection surface. In particular, it is preferable for the probe that the partially reflecting surface is a surface exhibiting maximum reflection among the total reflection surface in the probe. Still further, “fixed optical path length” means a physical optical path length of a media through which the light beams are transmitted, whereby an optical path length, which varies in accordance with the change of refraction index of media due to the temperature change, is not included.
The probe of the optical tomographic image measurement device described in claim 2 is characterized in that on the invention described in claim 1, an optical member having the partially reflecting surface on the probe is arranged to exhibit a position where an amount of the beam returning from the partially reflecting surface includes a predetermined ratio against an amount of the measurement beam entering the partially reflecting surface, whereby images, which are based on the reflected beam coming from the partially reflecting surface, are used so that images, which are based on the reflected beam from the tissue of the living subject, can be easily determined.
The probe of the optical tomographic image measurement device described in claim 3 is characterized in that on the invention described in claim 2, the predetermined ratio is equal to or greater than 60 dB, and equal to or less than 25 dB. In this case, 1 dB=−10 log(X[%]/100), and “X” represents a ratio of an amount of the beam coming from the partially reflecting surface, against an amount of beam entering the probe.
Interference signals generated in a common optical path (which is in the reference optical path only, or in the measurement optical path only), such as interference signals, based on the reflected beams coming from the partially reflecting surface and the reflected beams coming from the measurement subject, can be removed within a predetermined scope, if a balance detector as a detection device is used. In general, since the balance detector (for example, 80-MHz Balanced Receiver, made by NewFocus) can remove a common mode of 20-30 dB, if the reflectance on the partially reflecting surface in the probe is set to be equal to or less than 25 dB, the interference signals, based on the reflected beams coming from the measurement subject and the reflected beams coming from the partially reflecting surface, can be removed, so that clear optical tomographic image signals can be obtained. Further, if the reflectance of the partially reflecting surface in the probe is equal to or greater than 60 dB, the signals, which are generated by the interference of the reference beams passing through the reference path and the internal reflected beams, can be effectively detected by the optical tomographic image measurement device. However, if said reflectance is equal to or less than 60 db, the optical tomographic image signals of the internal reflection of the probe are so weak that the signals are very difficult to be detected.
The probe of the optical tomographic image measurement device described in claim 4 is characterized in that the probe in the invention described in claims 1-3 further includes: an optical fiber for receiving the measurement beam and returning the measurement reflected beam; a refractive index dispersion lens for transferring the measurement beam and the measured reflected beam; and a prism for outputting the measurement beam through the partially reflecting surface and receiving the measured reflected beam, wherein the refraction index dispersion lens and the prism are adhered onto each other, while keeping a predetermined positional relationships. Due to this, the amount of the returned beams, returning from the partially reflecting surface, can be controlled at a desired ratio, against the amount of conveyed measurement beams.
The probe of the optical tomographic image measurement device described in claim 5 is characterized in that in the invention described in claim 4, the refractive index dispersion lens and the prism are adhered onto each other while keeping a predetermined angle. Due to this, the optical amount of the beams returning from the partially reflecting surface can be easily controlled, against the optical amount of conveyed measurement beam.
The probe of the optical tomographic image measurement device described in claim 6 is characterized in that in the invention described in claim 4, the refractive index dispersion lens and the prism are adhered to each other while keeping a predetermined clearance. Due to this, the optical amount of the beams returning from the partially reflecting surface can be easily controlled, against an optical amount of radiated measurement beam.
The probe of the optical tomographic image measurement device described in claim 7 is characterized in that in the invention described in claims 1-6, the partially reflecting surface is placed at a position which keeps an optical path length from a focal point of the refractive index dispersion lens to be equal to or less than 10 mm. Due to this, both interference signals returned from the measurement subject and interference signals coming from the partially reflecting surface of the probe can be placed within a measurable scope in the depth direction of the optical tomographic image.
The measurable scope in the depth direction of the optical tomographic image depends on various factors, such as the number of samplings for detecting the interference signals, the coherence length of the light beam source, the light beam source transmittance of the measurement subject, or the like. As one of marks, Reilly length is considered. The Reilly length represents an approximate guide for the measurable scope, that is, the focal depth is double the Reilly length, and Reilly length Z is shown by Z=λ/(π·NA2), in which λ is wave length of the light beam source, NA is a light beam exhibiting an intensity of 1/e2 of the beam focused by a condenser lens. For example, regarding the optical tomographic image measurement device to be used for an in-vivo measurement, generally used are a light beam source exhibiting a wave length 1.3 μm, and a condenser lens (which is the refractive index dispersion lens in this case) exhibiting NA 0.01, so that the focal depth results in 8.3 mm. Accordingly, it is desirable to place the partially reflecting surface at a position which keeps the optical path length from the focal point of the refractive index dispersion lens to be equal to or less than 10 mm.
The probe of the optical tomographic image measurement device described in claim 8 is characterized in that the probe in the invention described in claims 1-3 further includes: an optical fiber for conveying the measurement beam and returning the measurement reflected beam; a lens for transferring the measurement beam and the measurement reflected beam; a flat plate for conveying the measurement beam through the partially reflecting surface and receiving the measurement reflected beam, and a lens barrel for uniting the optical fiber, the lens and the flat plate, wherein the flat plate united in the lens barrel is inclined against an optical axis. Due to this structure, the amount of beams returning from the partially reflecting surface can be controlled at a desired ratio, against the amount of radiated measurement beam.
The probe of the optical tomographic image measurement device described in claim 9 is characterized in that in the invention described in claim 8, the partially reflecting surface is placed at a position which keeps an optical path length from the focal point of the lens to be equal to or less than 10 mm. Due to this, both interference signals coming from the measurement subject and interference signals coming from the partially reflecting surface of the probe can be placed within a measurable scope in the depth direction of the optical tomographic image.
A method for adjusting a probe described in claim 10 is a method for adjusting a probe of an optical tomographic image measurement device including a main body for obtaining an optical tomographic image of a measurement subject and a probe for guiding a measurement beam to the measurement subject, wherein the optical tomographic image measurement device includes: a beam source for emitting low coherent beams; a beam dividing means for dividing the low coherent beams emitted from the beam source into a measurement beam and a reference beam; a reflection mirror for reflecting the reference beam divided by the optical dividing means and for giving a predetermined optical path length to the reference beam; an optical multiplexing means for multiplexing a measurement reflected beam coming from said measurement subject, at a time when the measurement beam coming from the probe is radiated onto the measurement subject, and the reference beam reflected by the reflection mirror, and an optical interference detection means for detecting the optical interfering beam which is interfered with the measurement reflected beam multiplexed by the optical multiplexing means and the reference beam, wherein the probe includes a partially reflecting surface for reflecting a part of the measurement beam at a position of a measurement optical path length, having been fixed, and guiding said part of the measurement beam to the optical multiplexing means, wherein while a measurement beam is sent to the partially reflecting surface and a return beam returning from the partially reflecting surface is detected, so that the partially reflecting surface is fixed to keep an attitude in such a manner that the amount of the return beam returning from the partially reflecting surface exhibits a predetermined ratio against the amount of the radiated measurement beam.
According to the present invention, while the measurement beam is sent to the partially reflecting surface, the return beam from the partially reflecting surface is detected, whereby the partially reflecting surface is controlled to keep its attitude in such a manner that the amount of the return beam returning from the partially reflecting surface exhibits a predetermined ratio against the amount of the measurement beam, whereby the optical path length to the partially reflecting surface can be fixed, and the optical path length of the reference beam is set to be equal to the optical path length to the partially reflecting surface. Accordingly, the image signals, which are based on the reflected beam coming from the partially reflecting surface concerning the optical tomographic image, can be detected with a high degree of accuracy. Further, when the probe is actually introduced into the body cavity of the real living subject, images, which are based on the reflected beam coming from the partially reflecting surface, are used so that images, which are based on the reflected beam coming from the tissue of the living subject, can be easily determined.
The method for adjusting the probe described in claim 11 is characterized in that, the predetermined ratio is equal to or greater than 60 dB, and equal to or less than 25 dB, in the invention described in claim 10.
The method for adjusting the probe described in claim 12 is characterized in that, in the invention described in claim 10 or 11, the probe includes: an optical fiber for conveying the measurement beam and returning the measurement reflected beam; a refractive index dispersion lens for transferring the measurement beam and the measurement reflected beam; and a prism for conveying the measurement beam through the partially reflecting surface and returning the measurement reflected beam, wherein the refraction index dispersion lens and the prism are adhered to each other, while keeping a predetermined positional relationships. Due to this, the amount of return beam, coming from the partially reflecting surface, can be controlled as a desired ratio, against the amount of radiated measurement beam.
The method for adjusting the probe described in claim 13 is characterized in that, in the invention described in claim 12, the refraction index dispersion lens and the prism are adhered to each other while keeping a predetermined angle. Due to this, the optical amount of the returned beam returning from the partially reflecting surface can be easily controlled, against the optical amount of radiated measurement beam.
The method for adjusting the probe described in claim 14 is characterized in that, in the invention described in claim 12, the refractive index dispersion lens and the prism are adhered to each other while keeping a predetermined clearance. Due to this, the optical amount of return beam returning from the partially reflecting surface can be easily controlled, against an optical amount of radiated measurement beam.
The method for adjusting the probe described in claim 15 is characterized in that, in the invention described in claims 10-14, the partially reflecting surface is placed at a position which keeps the optical path length from the focal point of the refractive index dispersion lens to be equal to or less than 10 mm. Due to this, both interference signals returned from the measurement subject and interference signals coming from the partially reflecting surface of the probe can be placed within a measurable scope in the depth direction of the optical tomographic image.
The method for adjusting the probe described in claim 16 is characterized in that, in the invention described in claim 10 or 11, the probe includes: an optical fiber for conveying the measurement beam and returning the measurement reflected beam; a lens for transferring the measurement beam and the measurement reflected beam; a flat plate for conveying the measurement beam through the partially reflecting surface and receiving the measurement reflected beam, and a lens barrel for uniting the optical fiber, the lens and the flat plate, wherein the flat plate united in the lens barrel is inclined against the optical axis. Due to this structure, the amount of return beam returning from the partially reflecting surface can be controlled at a desired ratio, against the amount of radiated measurement beam.
The method for adjusting the probe described in claim 17 is characterized in that, in the invention described in claim 16, the partially reflecting surface is placed at a position which keeps an optical path length from the focal point of the lens to be equal to or less than 10 mm. Due to this, both interference signal coming from the measurement subject and interference signal coming from the partially reflecting surface of the probe can be placed within a measurable scope in the depth direction of the optical tomographic image.
According to the present invention, a probe of the optical tomographic image measurement device and methods for adjusting said probe can be offered, wherein the probe is formed to be a simple structure, and the image signals are prevented from fixing to noises.
The embodiment of the present invention will now be detailed while referring to the drawings.
Control section CONT is configured to control probe driving device DR1 and mirror driving device DR2. Probe driving device DR1 can rotate probe 10, while mirror driving device DR2 can move reflection mirror MR at desirable lengths in the optical axial direction.
Light beam source SLD is formed of a laser beam source to radiate low coherent beams, such as SLD (Super Luminescent Diode), and ASE (Amplified Spontaneous Emission). Since optical tomograpghic image measurement device 1 functions to obtain tomographic images of a living subject in a body cavity serving as measurement subject 5, said device 1 can control the optical attenuation caused by optical scattering or absorption, to the lowest limit, preferably uses ultra-short pulse laser beam source for wide spectrum bands.
Optical dividing means BS, formed of a 1×2 optical fiber coupler, for example, functions to divide low coherent beam L, conveyed from light beam source SLD through optical fiber FB1, into measurement beam L1 and reference beam L2. Optical dividing means BS is optically connected to optical fiber FB2 and FB3, whereby measurement beam L1 is conveyed through optical fiber FB2, while reference beam L2 is conveyed through optical fiber FB3.
Since optical fiber FB2 is optically connected to probe 10 through detachable connector CT, measurement beam L1 is conveyed from optical fiber FB2 to probe 10 through connector CT. Connector CT, which functions to connect the end sections of the optical fibers to each other, is configured to hold lenses LS1 and LS2 by paired holders H1 and H2, which are relatively rotatable, wherein lenses LS1 and LS2 function to receive the optical beam outputted from the end section of one optical fiber, and to send said optical beam to the end section of another optical fiber. Even when holder H2 is rotated integrally with probe 10, holder H1 can be in the resting state. Accordingly, the optical fiber at the opposite side of probe 10 is not twisted.
Probe 10, connected to rotation driving unit 30 (
Flexible shaft 13 is accommodated in tube 11, and optical fiber B10 is accommodated in flexible shaft 13. Flexible shaft 13 is formed of double compression coils, formed of metallic wires wound in a spiral configuration, while their winding directions are different from each other. Symbol CL represents an optical axis of optical fiber FB10.
The top of flexible shaft 13 and the top of optical fiber FB10 are fixed on one end 14a of base 14, while prism 17 is fixed on the other end 14b of base 14. A fixing method of prism 17 will be detailed later. Ferrule 15 and refractive index dispersion lens (being a gradient index lens, or a GRIN lens) 16 are accommodated in base 14. Accordingly, measurement beam L1 outputted from optical fiber FB10 is guided by ferrule 15 and gradient index lens 16, and is then conveyed to prism 17.
Prism 17 reflects measurement beam L1, conveyed through optical fiber FB10, to side surface 11a of tube 11, that is, measurement beam L1 is conveyed through tube 11 and radiated to the measurement subject. Simultaneously, prism 17 receives reflected beam L3 reflected by measurement subject S on which measurement beam L1 has been radiated, and prism 17 reflects said beam L3 to optical fiber FB10.
Flexible shaft 13 and optical fiber FB10 are configured to be rotatable against tube 11 in a direction shown by arrow R. Due to the rotations of flexible shaft 13 and optical fiber FB10, base 14 and prism 17 are also rotated in direction R. Accordingly measurement beam L1, reflected by prism 17, is radiated onto measurement subject S, while said measurement beam L1 is rotating. Due to this, optical tomographic images in a rotating direction (which is a radial direction) in the body cavity can be obtained.
Rotary tube 22 is rotatably supported by fixed sleeve 20 through bearing 22a. Further, rotary tube 22 is fixed to flexible shaft 13, so that flexible shaft 13 is rotated due to rotation of rotary tube 22. Still further, connecting ring 23 is connected to rotary tube 22, and screw threads are formed inside connecting ring 23. After connecting ring 23 is fixed on rotary connector 32, rotary tube 22, rotary tube 22 is rotated in synchronization with rotary connector 32. Ferrule 24 is accommodated in rotary tube 22, so that optical fiber FB10 and optical fiber FB2 of rotation driving unit 30 are optically connected to each other through ferrule 24 (said connecting figure is not illustrated).
Operations of probe 10 and rotation driving unit 30 will now be detailed, while referring to
Coupler CPL, formed of 2×2 optical fiber, is configured to superpose reflected beam L4, reflected by reflection mirror MR, and reflected beam L3, reflected by measurement subject S, and divide said beams by 50:50 ratio, whereby signal intensities of interference signals are shifted to each other by phase π, so that interfering beams L3′ and L4′ are sent to interfering beam detecting device 70.
Interfering beam detecting device 70, also known as a balance detector, is configured to conduct a difference detection, that is, only an interference component of the interference signal is selected and detected. In detail, if the summation (hereinafter, referred to as “measurement optical path length”) of a total optical path length of measurement beam L1 and a total optical path length of reflected beam L3 is nearly equal to the summation (hereinafter, referred to as “reference optical path length”) of a total optical path length of reference beam L2 and a total optical path length of reflected beam L4, or if the difference between said two optical path lengths is within the coherence length, said two optical beams cause interference, and beat signals, due to the interference component, are created on the interference signals, when the wavelengths of light beam source SLD are scanned. Since the phase of the beat signal of the interference signals is shifted by it, due to the passage through the coupler exhibiting 50:50, when the difference of said two signals is obtained, the interference component of the interference signals, that is, only the beat signal can be selected and detected, and signals other than that can be subtracted, whereby depth information for the measurement subject can be obtained with high accuracy. Tomographic signals of the measurement subject is obtained due to a signal process operation of the interference signals, by a signal processing means which is not illustrated. Based on said tomographic signals, optical tomographic images are displayed on an image displaying means which is not illustrated. As detailed above, interfering beam detecting device 70 conducts the difference detection, which is one of means for effectively obtaining the interference component of the interference signals. Accordingly, it is possible for another means that the interference signals is directly detected without conducting the difference detection, and obtained interference signals is processed.
Optical tomographic image measurement device 1 will now be detailed below. In
Problems during the measurement will now be detailed.
When a probe is inserted in the cavity of the living subject, a problem is that the positional relationships are not obtained between the tissues as the measurement subject and the probe. As shown in
In a comparative example shown in
In this case, reflection mirror MR is shifted so that the reference optical path length can be adjusted to the measurement optical path length (or an optical path length further including an estimated length to the measurement subject) to bottom face 17c of fixed prism 17. Accordingly, the reflected beam reflected by bottom face 17c of prism 17 interferes to the reflected beam of the reference beam, and is shown as image signals MK in
Further, interfering beam detecting device 70 is configured to select the interference components of two interference signals, and to detect the difference. Accordingly, said device 70 can fundamentally cancel the reflected beam coming from bottom face 17c of prism 17, and the reflected beam coming from the measurement subject, both reflected beams exhibiting the same phase, so that no interference signals may be controlled not to appear. However, when the amount of reflected beams from bottom face 17c is excessively great, interfering beam detecting device 70 cannot effectively exhibit a canceling function. As shown by the dotted lines in
In the present embodiment, as shown in
In order to control image signals MK at a relatively low intensity from which image signals WS, based on the reflected beams from the measurement subject, can be distinguished, and in order to cancel the reflected beams from bottom face 17c and the reflected beams from the measurement subject, while all-purpose interfering beam detecting device 70, obtained at a low price, is used, it is preferable that the amount of light beams returning from bottom face 17c against the amount of measurement beams entering probe 10, (reflectance ratio) is controlled to be equal to or greater than 60 dB and equal to or less than 25 dB, wherein 1[dB]=−10 log(X[%]/100). “X” shows the ratio of the amount of beams returning from the partially reflecting surface against the amount of incident beams to the probe. In order to control the reflectance ratio to be in the predetermined scope, adjustment of probe 10 is important.
The base light beams, having entered probe 10, pass through refractive index dispersion lens 16, and go out from its end. Then said base light beams are incident to incident face 17a of prism 17, and are reflected by inclined face 17b. Some of said beams are reflected on bottom face 17c, and remaining beams pass through bottom face 17c, and do not return. The light beams reflected by bottom face 17c are reflected by inclined face 17b, and pass through incident face 17a. Subsequently, said beams pass through refractive index dispersion lens 16, and go out from probe 10 toward the outside. Said beams are incident to circulator CLT through optical fiber FB, thereby said beams are separated to enter optical amount detecting device PD. Said optical amount detecting device PD is configured to detect the reflected beam amount, and to memorize the basic light amount of the base light beams, that is, optical amount detecting device PD is configured to calculate a reflection index, while using the basic light amount and the reflected beam amount. Accordingly, the slanting angle of incident face 17c of prism 17 against the end of refractive index dispersion lens 16 is adjusted so as to make the reflectance ratio calculated by optical amount detecting device PD to be equal to or greater than 60 dB and equal to or less than 25 dB, after that, adhering agent 13 is filled between refractive index dispersion lens 16 and prism 17, so that refractive index dispersion lens 16 and prism 17 are fixed onto each other. Further, according to the reflectance index, which is calculated by optical amount detecting device PD, the reference optical path length can be adjusted.
In the same way as the above-detailed embodiment, the measurement beams, entering probe 10B through optical fiber FB, are ejected from the inner end of optical fiber FB, and are focused by condenser lens LS. Subsequently, said measurement beams are ejected toward the outside of probe 10B through plane parallel plate PP, whereby said measurement beams are radiated onto the measurement subject, which is not illustrated. In accordance with the inclining angle against an orthogonal direction of the axis of guide wire GW, the reflected beam amount coming from plane parallel plate PP changes. While the reflection ratio is measured by the measurement device shown in
The present invention is further possible to be applied on TD (Time Domain)—OCT measurement and FD (Fourier Domain)—OCT measurement, and the structure of the optical system is not limited to the structures shown in the embodiments, as far as said structure can detect the interference signals.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-261751 | Nov 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/069911 | 11/9/2010 | WO | 00 | 5/14/2012 |
