WO1994005209A1 - Optical ct apparatus - Google Patents
Optical ct apparatus Download PDFInfo
- Publication number
- WO1994005209A1 WO1994005209A1 PCT/JP1993/001220 JP9301220W WO9405209A1 WO 1994005209 A1 WO1994005209 A1 WO 1994005209A1 JP 9301220 W JP9301220 W JP 9301220W WO 9405209 A1 WO9405209 A1 WO 9405209A1
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- WIPO (PCT)
- Prior art keywords
- light
- optical
- optical fiber
- image
- measured
- Prior art date
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
- A61B5/0073—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence by tomography, i.e. reconstruction of 3D images from 2D projections
Definitions
- the present invention relates to an improvement in an optical C-ray apparatus, and more particularly to an improvement in a method of irradiating an object to be measured with light.
- a tomographic imaging device is widely used as a medical device.
- the types of CT devices include X-ray CT, NMRC CT, positron CT, and ultrasonic CT.
- the newest CT device is an optical CT device that uses visible light or near-infrared light.
- the knock projection method used in X-ray CT devices is used as the principle of tomographic image reconstruction.
- the projection data is obtained by irradiating each point of the device under test with light, measuring the intensity of light passing through the device under test from each direction, and measuring the intensity from each light incident point. This is the light transmittance of the object to be measured in each direction.
- the irradiation position of the light on the object to be measured is scanned over each point around the object to be measured, and each irradiation point is scanned. Each time, the transmittance of light in each direction must be measured.
- the scanning method of the light irradiating the object to be measured is the Methods such as those shown in Fig. 2 and Fig. 3 were used.
- the method shown in FIG. 2 is a method described in Japanese Patent Application Laid-Open No. 63-115550, in which the irradiation light source 21 and the photodetector 22 are combined into the same gantry 23. By rotating the gantry 23 around the DUT 20, the irradiation position of the DUT 20 and the measurement position of the transmitted light are changed. ing .
- the method shown in FIG. 3 is a method disclosed in Japanese Patent Application Laid-Open No. Sho 64-56411.
- the light guided from the light source 31 through the optical fin 32 is used by an optical scanner 33 using an oblique mirror 33a.
- the irradiation position of the light on the DUT 30 is scanned.
- the light transmitted through the DUT 30 is detected using a photodetector array 34 in which a large number of photodetectors are arranged, and each photodetection of the photodetector array 34 is performed.
- the measurement position of the transmitted light of the device under test is changed by electrically switching the element for use.
- FIG. 4 there is a method shown in FIG. 4 as a conventional technique.
- This method is a method disclosed in Japanese Patent Application Laid-Open No. 60-72542, in which the position of light irradiation on the object 40 and the position of the transmitted light from the object 40 are measured.
- optical filters 43 and 44 are used to switch between and.
- the methods shown in FIGS. 2 and 3 have a disadvantage that the equipment size is large because a relatively large mechanism is required. This drawback was achieved using optical fins.
- the method shown in Fig. 4 tried to remove it.
- optical measurement is a sequential monitoring technology of a plurality of measurement points.
- This technology uses light to transmit information from sensors installed at each measurement point, and switches between sending light to each sensor and receiving light from each sensor.
- an optical system consisting of an optical fiber and a trapezoidal prism is used. This method is disclosed in Japanese Patent Application Laid-Open No. 61-2760000.
- a rotary light shielding plate 42 having a single light passage hole is placed in front of the fiber fixing plate 46, and the light shielding plate 42 is rotated.
- light is sequentially incident on each optical fiber through the above-mentioned light passage hole. Therefore, only the light transmitted through the above-mentioned light passage hole is incident on the optical fin 43. Since the light irradiation position on the DUT 40 is switched by such a method, most of the light from the light source 41 is supplied by the light shielding plate 42.
- the light used to irradiate the device under test 40 becomes a very small part of the total output light from the light source 41. For this reason, a very high-output light source is required to obtain the amount of irradiation actually required for measurement.
- Another disadvantage of the method shown in FIG. 4 is that, since a single photodetector 47 is used, the intensity range of light incident on the photodetector 47 is extremely low. The reason for this is that a light detector 47 having a wide dynamic range is required as the light detector 47.
- the light transmitted through the object to be measured guided by the optical fin 44 from each measurement point around the object to be measured 40 is a single photodetector. It is detected by making it incident on 47 in time series. The amount of light transmitted through the object at each measurement point differs greatly at each measurement point, and its intensity range extends to several orders of magnitude. For this reason, the photodetector 47 needs an expensive photodetector having a measurable range of several digits.
- the purpose of the present invention is to provide a compact and inexpensive device configuration.
- the purpose is to provide an optical CT device.
- Another object of the present invention is to provide a method of irradiating an object to be measured with high use efficiency of light from a light source to an object to be measured.
- light from a light source emitting visible light or near-infrared light is converted into an optical fiber comprising a plurality of strands.
- the transmitted light from the DUT is also guided to the photodetector through the same optical fin as above.
- An image inverting optical element for inverting an image such as a trapezoidal prism line-symmetrically, for example, in the middle of the optical fiber, and the optical inverting element disposed before and after the image inverting optical element.
- An optical system consisting of two converging lenses is introduced, and the above-mentioned image inverting optical element is rotated to scan the irradiation position of the irradiation light on the object to be measured. At the same time, the measuring position of the transmitted light from the measured object is changed.
- a plurality of photodetectors are used to detect the transmitted light from the object to be measured, and the transmitted light from the object at each measurement position is respectively detected. Simultaneous detection by another photodetector. As a result, the efficiency of detecting transmitted light can be increased, and the measurable range is relatively narrow in conformity with the transmitted light intensity level at each transmitted light measurement position.
- Inexpensive photodetectors can be used.
- the trapezoidal prism described above penetrates the prism as shown in OPTI CS (Eugene Hecht, Alfred Zajac; Addison-Wesley Publishing Company, Inc .; 1974, Page 133). It has the function of inverting the light image upside down.
- the trapezoidal prism 51 is inserted between the two focusing lenses 52, 53, and the trapezoidal prism 51 is placed on the object plane and the image plane.
- the end face of the optical fiber 54 and the end face of the optical fiber 55 are respectively arranged. That is, the end face 54 -a of one optical fin 54 is placed on one focal plane of a lens system composed of a trapezoidal prism 51 and lenses 52, 53. Then, the end face 55 — a of the other optical fin 55 is placed on the other focal plane of the same lens system. With such a configuration, an image of one optical fiber end face is inverted and formed on the other optical fiber end face.
- the end face 5 of the optical fiber 55 is obtained.
- the array of the elementary images on the inverted image formed on 5 — a is as shown in Fig. (C). That is, the images of the strands a, b, c, d, e, f, g, and h are formed at the positions of a ', b', c ', d', e ', and fgh', respectively. It is imaged.
- the image of each strand interposes this line segment X.
- the images are formed at positions that are line-symmetrical to each other in the vertical direction. Accordingly, if the optical fiber strands on the end face 55_a of the optical fiber 55 are arranged at the positions of the individual wire images shown in FIG. The light emitted from each of the optical fiber strands of the optical fiber 54 can be made to enter the corresponding strand of the optical fiber 55.
- the trapezoidal prism 51 when the trapezoidal prism 51 is rotated, the end face image of the optical fiber 54 formed on the end face of the optical fiber 55 rotates. Therefore, by rotating the trapezoidal prism 51, the light from each strand of the optical fiber 54 is made incident on an arbitrary strand of the optical fiber 55. In other words, by rotating the trapezoidal prism 51, the distance between each strand of the optical fiber 54 and each strand of the optical fiber 54 can be increased. The optical connection can be switched.
- the trapezoidal prism 51 was used as an image inverting optical element for inverting an image in line symmetry, but this was achieved by combining a plane reflecting mirror as described above. Even if it is configured to perform the image reversal of the above, it is not a matter of course that the configuration is good.
- the main cause of the light attenuation that occurs when switching the optical coupling relationship between the two optical fins 54 and 55 is the trapezoidal prism 51 and the like. Surface reflections by the lenses 52 and 53 on both sides of the lens. However, since the reflectivity of this surface reflection is as small as a few percent per reflection surface, the above-mentioned switching of the optical coupling relationship : oj: o:% In this case, the optical attenuation is significantly smaller than that in the case of the prior art. As a result, the light transmission efficiency between the two optical fibers 54, 55 is greatly improved.
- FIG. 1 is a schematic configuration diagram of an optical CT apparatus according to an embodiment of the present invention.
- FIG. 2 is a schematic explanatory view showing one configuration example of a conventional optical CT device,
- FIG. 3 is a schematic explanatory view showing another configuration example of a conventional optical CT device
- FIG. 4 is a schematic explanatory view showing still another configuration example of the conventional optical CT device
- FIG. 5 is a diagram for explaining the principle of an optical scanning method using a trapezoidal prism according to the present invention.
- Fig. 6 is a schematic explanatory diagram showing the optical path of light inside the object to be measured.
- FIG. 7 is a schematic configuration diagram of an optical CT device according to another embodiment of the present invention.
- FIG. 8 is a schematic configuration diagram of an optical CT device according to still another embodiment of the present invention.
- FIG. 9 is a schematic explanatory view showing one configuration example of an image inversion optical element using a reflecting mirror.
- FIG. 1 shows a basic configuration of an optical CT device according to an embodiment of the present invention.
- reference numeral 11 denotes an object to be measured, which is a sample whose tomographic image is to be observed by the optical CT apparatus.
- 1 2 — 1 emits light to irradiate the DUT 1 1
- An optical fiber for guiding which consists of a large number of optical fiber wires.
- 1 2 — 2 is a jig for fixing and holding each optical fiber on the end face of the optical fiber 1 2 — 1 on the object side.
- Reference numeral 3 denotes a jig for fixing and holding each optical fiber at the end face of the optical fiber 12-1 opposite to the above.
- the optical fiber fixing jigs 1 2 1 2 and 1 2 3 are connected to the optical fiber 1 2 1 at both end faces by a single optical fiber strand. Each optical fiber is held so as to be arranged at regular intervals and intervals along the line.
- 13-1 is a trapezoidal prism
- 13-2 is a cylindrical case holding the trapezoidal prism 13-1.
- 1 3-3 is a gear set to rotate case 13-2.
- 1 3-4 is a small gear for transmitting the rotational force of the noise motor 13-5 to the gear 13-3.
- 1 2 — 4 is an optical fin, which is still composed of many strands. One end of each strand is fixed on one circumference by the optical fiber fixing jigs 12-6, as in the case of the optical fiber 12-1. It has been done.
- 1 2 — 5 c is the optical fiber whose one end is fixed and held on the optical fiber fixing jig 1 2 — 6 in the same manner as the optical fiber of the optical fiber 1 2 — 4. It is an ino strand.
- the optical fiber wires 1 2-5 c are for guiding light from the light sources 15-1 and 15-2, and the other end thereof is an optical branching element 12-2. — 8, Optical switch They are connected to light sources 15-1 and 15-2 via 1 2-7.
- the light splitting elements 1 2-8 are connected to the light switches 1 2-5 and the light sources 15-1, 15-2 guided through the optical filters 12-5 a. To split the light. The split light is transmitted to a photodetector (photomultiplier tube) 16-1 through an optical fin 12-5b and output from the photodetector 16-1. The power signal is amplified by an amplifier 17-1 and used as a monitor signal to monitor the intensity of the output light from the light sources 15-11 and 15-2. It is done. The wavelengths of the output lights from the light sources 15-1 and 15-2 are 770 nm and 813 nm, respectively.
- the 14-1 and 14-12 are focusing lenses.
- the two focusing lenses are lenses having the same focal length, and the optical fin 1 held by the optical fin fixture 1 2-3.
- the image of the end face of 2-1 is formed on the end face of the optical fiber 1 2-4 held by the optical fiber fixing jig 1 2-16, and similarly, the optical fiber is fixed.
- An image of the end face of 1 2 — 4 is held by the optical fin fixing jig 1 2 — 3 It is arranged and configured to form an image on the end face of the optical fiber 12-1.
- 18-1 is an AD converter
- 18-2 is a storage device
- 18-3 is a computing device
- 18-4 is a display device.
- Reference numeral 1911 denotes a clock signal generator, which controls an optical switch 12-7, an AD converter 18-1 and a storage device 18-2 and a pulse motor 13-5. Generates a clock signal to operate in synchronization.
- Reference numeral 1912 denotes a drive circuit for driving the pulse motors 13-5.
- Light from the light sources 15-1 and 15-2 is guided to the optical switch 12-7 by the optical fan.
- the optical switches 12-7 allow one of the light from the two light sources to enter the optical fiber 12-5a.
- the light incident on the optical fiber 12-5a is branched at a constant rate by the optical branching element 12-8.
- One of the branched lights is guided into the optical fiber 122b, and the other light is guided into the optical fiber 122c.
- the light guided into the optical filter 12-5b is detected by the photodetector 16-1 and the output signal of the detector is amplified by the amplifier 17-1 and then the AD signal is amplified.
- AD conversion is performed by the converter 18-1 and stored in the storage device 18-2.
- the stored data is used as a signal representing the light intensity from the light source in the arithmetic processing by the arithmetic devices 18-3.
- the optical switch 12-7 Switching of the light from both light sources is performed based on the clock signal from the clock signal generator 1911.
- the optical switches 12-7 are set to direct light of wavelength 77 Onm from the light source 15-1 into the optical fins 12-5a.
- the light having a wavelength of 770 nm guided into the optical fiber 1 2-5 a is branched by the optical branching element 12-8, and one of the branched lights is converted into the optical fiber.
- the optical fiber is fixed to the optical fiber fixing jig 1 2 — 6 through the 1 1 2-5 c and guided to the end face on the 6 side.
- the light is further transmitted to the optical fin fixing jig 1 by the optical system consisting of the lenses 14-2, 14-1 and the trapezoidal prism 13-1.
- the light is focused on the end face of one optical fiber strand held at 13 and irradiates the DUT 11 through the optical fiber strand. .
- the light applied to the device under test 11 is transmitted while scattered in the device under test 11, and the optical fiber fixing jig 1 provided around the device under test 11 is provided.
- the optical fin held in 2-2 enters each element wire of 1-2.
- the light transmitted through the DUT which enters the optical fibers of the optical fibers 1 2-1, passes through these optical fibers and then passes through the optical fibers.
- the fiber fixing jig 1 2 Emits light from the end face on the 3 side in the direction of the lens 14 11. These emitted lights are sent to an optical fin fixing jig by an optical system consisting of a lens 14-11, a trapezoidal prism 13-1 and a lens 14-2.
- the light fins held in 1 2 — 6 It is made to enter into each strand.
- each photodetector 16-2a, 1 6 — 2 b Each photodetector outputs an electric signal representing the intensity of the light incident on the photodetector, and this output signal is output from an amplifier 17-2 a, 17-2 b,. Each is amplified. The amplified signal is converted into a digital signal by the AD converter 18-1 and stored in the storage device 18-2.
- the object to be measured 11 is irradiated with light having a wavelength of 813 nm from the light source 15-2.
- the process of irradiating the DUT 11 with light and storing the intensity signal of the light transmitted through the DUT 11 in the storage device 18-2 is the same as that of the light source. This is the same as when the object to be measured is irradiated with light with a wavelength of 770 nm from 15-1.
- the trapezoidal prism 13-1 is rotated by the pulse motor 13-5 and the gears 13-14 and 13-3.
- the angle of rotation is (180 ⁇ ) degrees, where n is the number of wires of the optical fin 12-1.
- n is the number of wires of the optical fin 12-1.
- Fixing jig 1 1 2 Directly next to the optical fiber that the light was incident on before rotating the trapezoidal prism on the 3rd end face (rotation direction) Immediately after seeing, it will be incident on the next) optical fiber.
- the irradiation position of the light on the DUT moves by one strand from the irradiation position before rotating the trapezoidal prism in the direction corresponding to the rotation direction of the trapezoidal prism. It will be.
- the optical correspondence between the optical fins 1 2, 1, and 1 2-4 by the rotation of the trapezoidal prism 1 3-1 by (180 ⁇ ) degrees Is shifted by one element, so the transmitted light from the DUT transmitted from the optical fins 1 2-1 to the optical fins 1 2-4 side is also The transmission is performed in a correspondence that is shifted by one strand compared to before the rotation of the trapezoidal prism.
- the specific strand of the optical fiber 12-1 corresponds to the specific strand of the optical fiber 12-4 (optical
- the rotation direction of the trapezoidal prism is smaller than that of the above-mentioned specific wire of the optical fin 12-1.
- the strand at a position shifted by one strand corresponds to the above-mentioned specific strand of the optical fiber 124 (transmits light).
- the operation described first is performed again.
- the light transmitted through the DUT when the DUT is irradiated with light from the new irradiation position Measure the intensity of and store it.
- the stepwise rotation of the trapezoidal prism described above is repeated until the irradiation position of the light on the DUT 11 makes one rotation around the DUT 11. In this way, multi-point scanning of the light irradiation position on the object 11 and measurement and storage of the transmitted light intensity of the object in each direction for each irradiation position are performed.
- FIG. 6 shows the arrangement of the optical fins around the object to be measured in Fig. 1.
- reference numeral 61 denotes an object to be measured
- 62-1, 62-2, ..., and 62-n abut the periphery of the object to be measured, and the end surface thereof contacts the object to be measured.
- These are optical fiber strands that are arranged in such a way as to make them smooth.
- 6 3-2, 6 3-3, ⁇ ⁇ ⁇ , 6 3-n are the light irradiation point of the optical fiber for light irradiation 62 1-1 and the light filter for transmitted light measurement. It is a straight line that connects the transmitted light measurement points by the Iva strands 6 2-2, ⁇ ⁇ ⁇ , 6 2-n.
- the optical fiber 62-5 is used.
- the light transmitted to the transmitted light measurement point can be considered to be transmitted near the straight line 63-3-5.
- the intensity of light transmitted through the DUT along the straight line 63-5 and incident on the optical fin 62-5 depends on the light absorption and light scattering inside the DUT. It has been attenuated. did Therefore, if the intensity of this transmitted light is measured, the attenuation ratio of the transmitted light along the straight line 63-5 can be determined from the measured value.
- the measurement of the transmittance of a single wavelength of light alone does not distinguish whether this attenuation is due to light scattering or attenuation due to light absorption. No. Therefore, in order to determine the rate of attenuation due to light absorption, the transmittance for each wavelength of light was measured using two wavelengths of light, and the two wavelengths were measured. Calculate the decay rate due to light absorption from the measured values.
- the reason that the wavelengths of the light used for the measurement are 770 nm and 815 nm is that when the object to be measured is a living body, the light with the wavelength of 770 nm is contained in living blood This is because, while the absorption by hemoglobin is large, the light with a wavelength of 813 nm has little absorption by this hemoglobin. That is, since light having a wavelength of 813 nm has little absorption by hemoglobin, the attenuation upon transmission is mostly due to light scattering. You can think about it. In contrast, light having a wavelength of 770 nm is attenuated by both absorption and scattering when passing through a living body. Therefore, hemoglobin is obtained by subtracting the attenuation rate of light with a wavelength of 813 nm from the attenuation rate of light with a wavelength of 770 nm. The light decay rate based on the light absorption can be calculated.
- the attenuation factor due to the light absorption of the transmitted light in each direction from the irradiation point of the light to the measured object is obtained from the transmitted light intensities of the two wavelengths. This is what I was asked to do
- the attenuation data due to a series of light absorptions for the transmitted light in each direction from one light irradiation point is projected to that light irradiation point. This is called data.
- the above-mentioned method of rotating the trapezoidal prism in small steps at small angles is used to rotate the point of light irradiation on the object to be measured one turn around the object to be measured. Measure the projection data for the light irradiation point.
- the projection data measured in this way is stored in the storage device 18-2.
- the tomographic image of the object to be measured is synthesized by performing the following arithmetic operations. First, the Fourier transform of the projection data for one light irradiation point is performed. Next, a filter function prepared separately is applied to the Fourier-transformed data, and then the Fourier-transformed data is inversely Fourier-transformed. Such an operation is performed on data for all light irradiation points. Then, the inverse Fourier transformed data is further divided into the measured object position which is divided from the position of each light irradiation point and the position of each transmitted light measurement point. The two-dimensional distribution (tomographic image) of the object to be measured inside the object to be measured is synthesized by superimposing them according to the internal position.
- Such a method of synthesizing a tomographic image is a method known as the Knock Project X Xion method, and its details are described in “Image Reconstruction from Projection (T. Herman; Academic Press) ". Operations like this The operation is performed in the arithmetic unit 18-3 based on the data stored in the storage unit 18-2, and the synthesized tomographic image of the measured object is displayed on the display unit 18-8. It is displayed in 4.
- the present embodiment relates to an optical CT device improved so as to eliminate fluctuations in light transmission efficiency between optical fibers.
- the basic configuration of the device of this embodiment is the same as that of the previous embodiment 1 (Fig. 1), but in this embodiment, the core of the optical fiber used (the optical fiber) is used. The difference is that the diameter of the transmission section is set in a specific relationship.
- each of the optical fibers 12-1 having a core diameter of 0.5 mm is used for each of the strands.
- the core diameter is 3.0 mm.
- a core straighter 0.125mm.
- the transmission of light between the optical fins is through a lens.
- the light guided from the light source 15-1 by the optical fin 12-5c passes through the lens 14-12 to the trapezoid prism 13-1. After being transmitted through the prism, the light is focused on the end face of the optical fin 12-1 by the lens 14-1.
- the optical fins 1 2 are optical fins 1 2 —
- the end face image of the optical fin 1 2 — 5 c is formed on the end face of 1.
- the size (diameter) of this image is the lens 14-1
- the optical fiber Since the focal lengths of 14 and 12 are the same, the optical fiber is 1 2- It is the same as the core diameter of 5c, which is 0.125 mm. If the size of this image is larger than the core diameter of each of the wires in the optical fiber 1 2 — 1, the optical fiber 1 2 — 5 c All of these lights cannot be made to enter the elementary wire of the optical fiber 1 2-1, and a part of the light will be lost, and the intensity of the light applied to the object to be measured Is attenuated. Also, if the size of this image is the same as the core diameter of each wire of the optical fins 12-1, a slight change in the rotation angle of the trapezoidal prism will occur.
- the core diameter of each of the optical fibers 12-1 is 0.5 mm, and the end images of the optical fibers 12-5 are the same. Because it is sufficiently larger than the size (diameter: 0.125 mm), the light from the optical fiber 12-5c is not affected even if the imaging position is slightly shifted. All light can be incident on the corresponding strand of the optical fiber.
- the size of the end face image of the optical pho- no-122, formed on the end face of the optical pho- no-124, is 0.5 mm in diameter.
- the core diameter of each strand of the optical fiber 12-4 is set to 3 mm, which is larger than the diameter of the end face image of the optical fiber 12-1. For this reason, the light passes through each of the optical fibers 1 2-1. All of the transmitted light transmitted from the device under test is transmitted to the corresponding optical fiber 12-4 (73), transmitted to the corresponding photodetector, and detected.
- the optical fiber wires 12-5 for guiding the light from the light sources 15-1 and 15-2 to the lens 14-12 are used.
- the core diameter of c is smaller than the core diameter of each element wire of 1 2 — 1 for guiding the light from the lens 14-1 to the surface of the DUT.
- the trapezoidal prism is set smaller than the core diameter of each strand of 4, so the trapezoidal prism 1 3 — 1 is rotated and then stopped.
- 1 3 The stop position of 1 is slightly out of the specified position. What et al adversely of stomach affect the optical transmission efficiency between Kakuhikarifu A i Bas strands be that. As a result, the fluctuation of the measurement data is reduced, and a tomographic image with good reproducibility can be obtained.
- FIG. 7 shows a basic configuration of an optical CT device according to another embodiment of the present invention.
- the main difference between the present embodiment and the first embodiment is the method of irradiating the object to be measured with light.
- the first embodiment light from the light source 15-1 and the light from the light It is switched according to switches 1 2-8, and the light of different wavelengths from each light source is alternately irradiated on the DUT.
- the object to be measured is simultaneously irradiated with two lights having different wavelengths from both light sources.
- the light from the light source 15-1 is transmitted to the optical branching element 12-8a by the optical fin 12-5a.
- the optical branching element 1 2 — 8 a is used to transmit the light to the optical fin 12-5 b and the light to be transmitted to the optical fin 12-5 c.
- the light branched to the optical fins 12-5b is transmitted to the photodetector 16-1a and detected.
- the output signal of the detector 16-1a is amplified by the amplifier 17-1a, converted into a digital signal by the AD converter 18-1 and stored in the storage device 18-2. Will be remembered within. This signal is used as a signal representing the intensity of light emitted from the light source 15-1 to the object to be measured in the arithmetic processing by the arithmetic unit 18-3. It is.
- the light branched to the optical fiber 12-5c side is transmitted to the end of the fixture 12-2-6 through the optical fiber 12-5c. After that, the object to be measured 11 is irradiated through the same route as in the first embodiment.
- the output light from the light sources 15-2 is also changed by the optical fins 12-5d in accordance with the optical fins 12-5d.
- One of the split lights is an optical fin. It is sent to photodetector 16 — lb through one 5e and detected. This detection signal is amplified by an amplifier 17-lb, converted into a digital signal by an AD converter 18-1, and stored in the storage device 18-2.
- the other split light is transmitted to the fixing jig 12-6 side end face via the optical fiber 12-5 f, and thereafter, the case of the first embodiment is applied.
- the object to be measured 11 is irradiated through the same route as described above.
- two light beams having different wavelengths from the light sources 15-1 and 15-2 are radiated on the DUT 11 at the same time.
- the light transmitted through the DUT 11 is transmitted from the optical fin 12-1 to the optical fin in the same manner as in the first embodiment.
- the two wavelengths of the transmitted light to be measured entering each strand of the optical fins 1 2-4 are the dichroic prisms 16-4 a, connected to each strand. 16-4 b, ⁇ ⁇ ⁇ wavelength separation.
- the dichroic prism 16-4 a is capable of transmitting light of the first wavelength from the light source 15-1 and light of the second wavelength from the light sources 15-12. Separate the light source 1 5 —
- the light of the first wavelength from 1 is sent to the photodetector 16 — 2a, and the light of the second wavelength from the light source 15 — 2 is sent to the photodetector 16 —
- the detection signals from the photodetectors 16-2a and 16-3a are amplified by the amplifiers 17-2a and 17-3a, respectively, and then the AD converters 18-8 — Sent to 1.
- the dichroic prism 16-4b The separated lights of the respective wavelengths are detected by photodetectors 16-2b and 16-3b, and the respective detection signals are amplified by amplifiers 17-2b and 17-2b.
- the signal is amplified by 1 7-3 b and sent to the AD converter 18-1.
- the light transmitted through the DUT incident on the other strands of the optical fins 12-4 is also separated by wavelength and detected, and the detected signals are amplified. After that, it is sent to AD converter 18-1.
- the DUT 11 is irradiated with two lights having different wavelengths at the same time, and the two DUTs having different wavelengths from the DUT are irradiated. Detection of the transmitted light of the measured object is also performed at the same time.
- the rotation of the trapezoidal prism 13-1 scans the irradiation position of light on the object under measurement, and the signal from the AD converter 18-1 is stored in the storage device 18-2.
- the arithmetic unit 18-3 uses the stored data to perform an operation for synthesizing a tomographic image of the object to be measured, and displays the synthesized tomographic image of the object to be measured.
- the process of displaying on the device 18-4 is the same as that of the first embodiment.
- measurement using two different lights can be performed at the same time, so that the measurement time can be reduced.
- the method is suitable for measurement in the case where the state inside the DUT is changing over time.
- FIG. 8 shows a light C according to still another embodiment of the present invention.
- the basic configuration of the T device is shown.
- This embodiment uses a DC motor 13 instead of the pulse motor 13-5 used to rotate the trapezoidal prism 13-1 in the third embodiment. — This is an example using 6.
- These DC motors 13-6 are driven to rotate by DC power supplies 19-12a.
- the rotation angle of the DC motors 13-6 is detected by the mouth encoder 13a-16a, and the detected rotation angle signal is converted by the AD converter 17-4. Then, the signal is converted into a digital signal and sent to the frequency divider 17-5.
- One of the frequency dividers 17-5 is turned into a trapezoidal prism 13-1 rotation angle based on the rotation angle signal from the AD converter 17-4, and one for every (180 / n) degree Generates a pulse signal.
- n is the number of strands of the optical fiber 12-1 which is fixed and held by the fiber fixing jig 12-3.
- the DC motor 13-6 is rotated, and the trapezoidal prism 13-1 is driven through the driving force transmission mechanism by the gears 13-4, 13-3. It is rotating.
- the image inversion optical system is composed of the lens 14-11, the trapezoidal prism 13-1, and the lens 14-12.
- Optical fiber 1 2 — 4 fiber fixing jig 1 2 Optical fiber 1 2 — 1 imaged on 6-side end face Fiber fixing jig 1 2 — The image on the end face on the third side rotates.
- the optical fins 12-4 are fixed to the fins.
- Jig 1 2 At the end face on the 6-side, the end face image of each optical wire of the optical fin 12-1 and the optical fin 12 4 The end face of the strand overlaps.
- light from the light sources 15-1 and 15-2 is applied to the device under test 11, and the light transmitted through the device under test 11 is transmitted to the optical fins 12-4. Is transmitted within each element wire.
- the light transmitted into each of the optical fibers 1 2-4 has a wavelength according to the dichroic prism 16-a, 16-4 b,. Will be separated.
- the wavelength-separated light is divided by the photodetectors 16-2a, 16-2b, ... and the photodetectors 16-3a, 16-3b, ...
- the detected signals are detected by amplifiers 17-2a, 17-2b,... And amplifiers 17-3a, 17-3b,. After being amplified, it is sent to the AD converter 18-1.
- the frequency divider 17-5 When such a state occurs, the frequency divider 17-5 generates a noise signal based on the rotation angle signal from the encoder 13-6a. This pulse signal is sent to the AD converter 18-1 and the storage device 18-3.
- the AD converter 18-1 performs a new AD conversion operation every time this pulse signal is transmitted.
- the storage devices 18-2 also perform data fetch operations in synchronization with this pulse signal.
- the trapezoidal prism 13 by the DC motor 13-6 The optical fin 12 formed on the end face of the optical fin 12-4 with the rotation of 13-1
- the end face image of 3 rotates and the optical fin At the end of each strand of 1 2-4, the end faces of the different strands of optical fins 1 2-3 are superimposed. That is, the irradiation position of the light on the DUT 11 changes one after another, and the above-described measurement operation of the transmitted light intensity of the DUT is repeated for each irradiation position. In this way, the projection data of the DUT 11 is measured, and the calculation is performed by using the projection data. Thus, a tomographic image of the DUT 11 is formed.
- the function of the trapezoidal prism used as the image inverting optical element in the above embodiments can be realized by an optical element configured by combining a plane reflecting mirror. be able to .
- the present embodiment relates to an image inversion optical element constituted by combining such a plane reflecting mirror.
- Fig. 9 shows the structure of an element that achieves the same function as a trapezoidal prism by combining this plane reflector.
- This element has a first reflecting surface 92a, a second reflecting surface 93a, and a third reflecting surface 92c.
- the first reflecting surface 92a and the third reflecting surface 92c are formed by forming an aluminum thin film for reflecting light on two surfaces of a glass triangle prism 92b. It is composed of
- the second reflecting surface 93a is formed by providing an aluminum thin film for reflecting light on the surface of a glass reflecting plate 93b. Let's do.
- the triangular prism 9 2 b is circled through the support 95.
- the reflector 96 b is fixed to the inner surface of the cylindrical body 96 directly to the inner surface of the cylindrical body 96.
- the support 95 is formed by connecting the triangular prism 92 b to its center position (the intersection of the first reflection surface 92 a and the third reflection surface 92 c with the support 95). Position that divides the distance from the bottom surface by 2 minutes) onto the center axis of the cylinder 96.
- a gear 97 for rotating the cylinder 96 is provided on the outer periphery of the cylinder 96.
- the light rays 9 la, 9 1b, and 9 1c incident on this element are reflected by the second reflecting surface 93 a, so that the triangular prism 9 2b With respect to the line Y drawn at the center position, the light is inverted in a vertically symmetric manner with respect to the line Y, and emitted as light rays 9a, 9b, and 94c, respectively.
- the incident light beam 91a located at the top of the incident light beams and the outgoing light beam 94a located at the bottom of the outgoing light beams are the same.
- the incident light beam 91c located at the bottom of the incident light beams is regarded as the emergent light beam 94c located at the top of the emitted light beams. And is emitted. Accordingly, the image of light incident on this element is emitted as an image of light that is inverted symmetrically in the vertical direction with respect to the line segment Y.
- the image reversal element formed by combining the plane reflecting mirrors shown in FIG. 9 has a function of reversing the image line-symmetrically, similarly to the trapezoidal prism described above. And this image counter By rotating the inverting element, the inverted image emitted from the element can be rotated by twice the rotation angle of the element. Therefore, the trapezoidal prism used in the first to fourth embodiments uses the image inverting optical element composed of the reflecting mirror shown in FIG. 9 in the first to fourth embodiments. Even if it is used in place of the prism, the effects described in the embodiments can be realized as in the case of the trapezoidal prism.
- the present invention light can be scanned on the object at high speed, and thus it is necessary for measurement. Time can be shortened. If the measurement time is long, there is a problem that the internal state of the DUT changes during the measurement, but according to the present invention, the state of the DUT changes. Since the measurement can be completed in a short time, an accurate tomographic image can be obtained.
- a device having a wide light intensity range (dynamic range) that can be measured as a photodetector is not required, and therefore, it is not necessary.
- An inexpensive photodetector can be used, which has the advantage of being economically superior.
- the intensity of the light transmitted through the device under test varies greatly depending on the distance that the light has transmitted through the device under test. Therefore, the intensity of the light transmitted through the object to be measured incident on each strand of the optical fiber also differs greatly depending on the strand. For this reason, one light detector measures the transmitted light intensity of all optical fiber wires. This requires the use of a very wide dynamic range photodetector.
- the transmitted light intensity of each element wire of the optical fibers 12 to 4 is measured using a separate photodetector.
- the intensity of the light transmitted through the object under test is limited within a limited range. It only changes. Therefore, it is not necessary to use an individual with a wide measurement range as an individual photodetector. Simply adjust the measurement level of each detector according to the intensity level of the incident light. As a result, an expensive photodetector is not required, and the device can be manufactured at low cost.
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- Engineering & Computer Science (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
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- Molecular Biology (AREA)
- Surgery (AREA)
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Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP93919591A EP0614645A4 (en) | 1992-08-31 | 1993-08-30 | COMPUTER OPTICAL TOMOGRAPHY APPARATUS. |
US08/204,370 US5408093A (en) | 1992-08-31 | 1993-08-30 | Optical computed tomography equipment having image inverting optical device |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP4/230926 | 1992-08-31 | ||
JP23092692 | 1992-08-31 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1994005209A1 true WO1994005209A1 (en) | 1994-03-17 |
Family
ID=16915453
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP1993/001220 WO1994005209A1 (en) | 1992-08-31 | 1993-08-30 | Optical ct apparatus |
Country Status (3)
Country | Link |
---|---|
US (1) | US5408093A (ja) |
EP (1) | EP0614645A4 (ja) |
WO (1) | WO1994005209A1 (ja) |
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WO1997018755A1 (fr) * | 1995-11-17 | 1997-05-29 | Hitachi, Ltd. | Instrument servant a des mesures optiques sur des corps vivants |
JP2001521147A (ja) * | 1997-10-16 | 2001-11-06 | ザ・リサーチ・ファンデーション・オブ・ステート・ユニバーシティ・オブ・ニューヨーク | 近赤外診療光学走査装置 |
JP2003516522A (ja) * | 1999-10-26 | 2003-05-13 | エルディム | 対象物からのスペクトル発光の空間分布を測定するための装置 |
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- 1993-08-30 US US08/204,370 patent/US5408093A/en not_active Expired - Fee Related
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- 1993-08-30 EP EP93919591A patent/EP0614645A4/en not_active Withdrawn
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
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WO1997018755A1 (fr) * | 1995-11-17 | 1997-05-29 | Hitachi, Ltd. | Instrument servant a des mesures optiques sur des corps vivants |
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JP2003516522A (ja) * | 1999-10-26 | 2003-05-13 | エルディム | 対象物からのスペクトル発光の空間分布を測定するための装置 |
Also Published As
Publication number | Publication date |
---|---|
EP0614645A1 (en) | 1994-09-14 |
US5408093A (en) | 1995-04-18 |
EP0614645A4 (en) | 1996-04-03 |
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