JP2004333344A - Optical measurement method and device - Google Patents

Abstract

An object of the present invention is to provide a small and simple device for efficiently measuring information inside a living body in a wide space area with high resolution, temporally and systematically, and furthermore compactly and simply.
The apparatus has a small and simple configuration by using a plurality of light beams for measurement, and further uses high-resolution light in a wide spatial region by using light modulated with different code patterns for a plurality of measurement positions. , And efficiently measure in terms of time and system.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a biological light measurement device and an image creation method in the device, that is, a biological light measurement device and an image creation method for measuring information inside a living body using light and imaging a measurement result.
[0002]
[Prior art]
[Patent Document 1] JP-A-57-115232 [Patent Document 2] JP-A-63-260532 [Patent Document 3] JP-A-63-275323 [Patent Document 4] JP-A-05-317295 Gazette [Non-Patent Document 1] "Experimental study of the effect of absorbing and transmitting inclusions infusions in high sci- entation, October 10, 2010," Experimental study of the effect of absorbing and transmitting and inclusion. Applied Optics, 33, 28, 6692-6698 (Applied optics, 33, 28, 6692 (1994)).
There is a demand for a device for simply measuring the inside of a living body without damaging the living body in fields such as clinical medicine and brain science. For example, when the head is specifically considered as a measurement target, measurement of brain diseases such as cerebral infarction and intracerebral hemorrhage, and measurement of higher brain functions such as thinking, language, and movement can be mentioned. In addition, such a measurement target is not limited to the head, and may include preventive diagnosis of heart diseases such as myocardial infarction in the chest and visceral diseases such as kidney and liver in the abdomen. When measuring a disease or a higher brain function in the brain by considering the head as a measurement target, it is necessary to clearly specify a diseased part or a functional region. For this reason, it is very important to measure a wide area of the head as an image. An example of this importance is that positron emission tomography (PET) and functional nuclear magnetic resonance tomography (fMRI) are now widely used as brain image measurement devices. While these devices have the advantage of being able to measure a wide area inside a living body as an image, the devices are large and their handling is complicated. For example, the installation of these devices requires a dedicated room, and of course, the movement of the devices is not easy and the restraint on the subject is high. Further, since a dedicated person for maintenance and management is required, the operation of the apparatus requires enormous costs.
[0003]
On the other hand, optical measurement is very effective against the above-mentioned demand. The first reason is that normal and abnormal organs in the living body, as well as activation of the brain related to higher brain functions, are closely related to oxygen metabolism and blood circulation in the living body. This oxygen metabolism and blood circulation correspond to the concentration of a specific pigment (hemoglobin, cytochrome aa3, myoglobin, etc.) in the living body, and the pigment concentration is determined from the amount of light absorbed in the visible to infrared region. The second and third reasons why optical measurement is effective are that light is easy to handle with an optical fiber and that it does not harm the living body when used within the safety standards. As described above, optical measurement has advantages that PET and fMRI do not have, such as real-time measurement and quantification of dye concentration in a living body, and a measurement device using light is suitable for miniaturization and simplification. Utilizing such advantages of optical measurement, a device that irradiates a living body with light having a wavelength from visible to infrared and detects light reflected from the living body to measure the inside of the living body is disclosed in, for example, Japanese Patent Application Laid-Open No. JP-A-115232, JP-A-63-260532, JP-A-63-275323 or JP-A-5-317295.
[0004]
[Problems to be solved by the invention]
However, the above-described living body measurement technology using light can measure only a specific position or a limited narrow region of a living body, and does not consider image measurement in a wide spatial region of the living body.
[0005]
Here, specific problems of the light measurement method and the light irradiation / detection point arrangement according to the conventional method will be described below. First, an optical measurement method will be described. Image measurement in a wide spatial area requires light irradiation and detection at multiple points.
An example of this multi-point measurement will be briefly described with reference to FIG. FIG. 2 is a plan view showing the arrangement of irradiation positions, detection positions, and measurement positions in optical measurement. In this example, three positions (“irradiation position 1”, “irradiation position 2”, “irradiation position 3”) on the surface of the object are irradiated with light, and three positions (“detection position 1”) on the surface of the object are irradiated. , "Detection position 2", and "detection position 3"). In the case of image measurement, the measurement position must be specified. Regarding light propagation in a light scatterer, for example, in a living body, see, for example, “Experimental study of the effects of absorptive and transmissive inclusions in a high scattering medium” by NC Bruce (Experimental). study of the effect of absorbing and transmitting inclusions in high scattering media ", Oct. 1, 1994, Applied Optics, Vol. 33, No. 28, p. )).
[0006]
FIG. 3 is a cross-sectional view schematically showing light propagation in a scatterer in optical measurement based on the report. From FIG. 3, it can be seen that the vicinity of the midpoint of the light irradiation position and the detection position has much information of a place deep from the surface. Therefore, when measuring a deep part of a living body, for example, a further deep part of the skin or bone from the skin, the midpoint of the irradiation / detection position is the measurement position. For such measurement, it is necessary to determine the information at the measurement position specified for each pair by irradiating and detecting position as a pair.
[0007]
For example, in the measurement arrangement of FIG. 2, it is assumed that light is simultaneously irradiated from these three irradiation positions and detected at three detection positions. In this case, in the measurement at the “measurement position 2” which is the midpoint between the “irradiation position 2” and the “detection position 2”, the light detected at the “detection position 2” is irradiated at the “irradiation position 2”. Light must be measured accurately. However, in this case, the light detected at “detection position 2” includes not only light from “irradiation position 2” but also light irradiated from “irradiation position 1” and “irradiation position 3”. Talk occurs. Therefore, the detected light amount of the light irradiated at “irradiation position 2” cannot be accurately obtained. In order to solve such a problem, a configuration is conceivable in which measurement positions are sequentially switched in time series using a switch or the like for each irradiation position.
[0008]
FIG. 5 shows this configuration as a comparative example. Reference numerals 501 to 504 denote light irradiation devices, 505 denotes light passing through the inside of the scatterer, 506 denotes a light receiving unit, 507 denotes a state of specifying an irradiation position, and 508 denotes an irradiation / detection arrangement diagram. FIG. 5 shows an example in which signals from the four irradiation positions are detected at the detection positions. However, since the timing of irradiating light from each irradiation position differs from T1, T2, T3, and T4, respectively, Crosstalk as described above does not occur. However, to switch between many irradiation positions, the time for switching is required, which is inefficient in time. In order to further improve the resolution, it is necessary to increase the number of measurement points measured per unit time, but as a result, the time allocated to one irradiation position, that is, the irradiation time is shortened, so that the light that can be detected on the receiving side is reduced. There is a problem that the detected light amount is insufficient.
[0009]
As another realization method, an apparatus that irradiates a plurality of portions of the scatterer with light of a plurality of wavelengths in the visible to infrared region and detects and images light passing through the inside of the scatterer from the plurality of portions of the scatterer, For example, an oscillator, a semiconductor laser, an optical fiber, etc., generate light having different modulation frequencies and irradiate the light to each of a plurality of parts, for example, to an optical fiber, a photodetector including a photodiode, a lock-in amplifier, an A / D converter, etc. A method is conceivable in which modulation measurement is performed on transmitted light obtained at a plurality of detection sites, so that information inside the scatterer corresponding to individual irradiation positions and detection positions is imaged.
[0010]
FIG. 6 shows this configuration as a comparative example. Reference numerals 601 to 604 denote light irradiation devices using a plurality of modulation frequencies, reference numeral 605 denotes light passing through the inside of the scatterer, reference numeral 606 denotes a configuration of a light receiving unit using a plurality of modulation frequencies, reference numeral 607 denotes an irradiation position specification using a plurality of modulation frequencies, and reference numeral 608 denotes a plurality of modulation frequencies. FIG. 6 is a light irradiation / detection arrangement diagram according to the present invention.
[0011]
In this method, light of a different modulation frequency is emitted from each part, and light detection of a desired modulation frequency is performed by a lock-in amplifier on the receiving side, so that crosstalk does not occur in principle, but a high-precision lock-in amplifier is used. It is necessary to increase the number of measurement points to be measured in order to improve the resolution.As a result, light with a modulation frequency proportional to the number of measurement points is generated. It is necessary to prepare a lock-in amplifier or the like corresponding to the frequency, and there is a problem that the device scale becomes large.
[0012]
SUMMARY OF THE INVENTION An object of the present invention is to solve such problems when aiming at improving the resolution, and to provide a small and simple device using light, which can efficiently and temporally and systematically information inside a living body in a wide space area. An object of the present invention is to provide a device for measuring an image.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention irradiates a plurality of portions of the scatterer with light of a plurality of wavelengths in the visible to infrared region, and detects and images light passing through the inside of the scatterer from the plurality of portions of the scatterer. In an apparatus that performs, for example, an oscillator, a semiconductor laser, an optical fiber, and the like, irradiates the light with the same frequency and modulates it with a different code pattern for each of a plurality of portions, for example, an optical fiber, a photodetector including a photodiode, A / D converters and the like measure the correlation between the transmitted light obtained at a plurality of detection sites and the code pattern used on the transmission side, so that the inside of the scatterer corresponding to each irradiation position and detection position is measured. Is configured to be imaged. Such a system is also called a spread spectrum modulation system.
[0014]
In the measurement method of the present invention, different code patterns are generated, electromagnetic waves modulated with different code patterns are generated, the electromagnetic waves are applied to a plurality of locations on the sample, and the electromagnetic waves that have passed through the inside of the sample are applied to a plurality of locations on the sample. And performs a correlation operation with the code pattern on the electromagnetic waves obtained from a plurality of locations on the sample, and obtains information on the sample based on the result of the correlation operation. With this configuration, information at a plurality of locations on the sample can be obtained at the same time.
[0015]
In addition, the measurement device of the present invention includes a plurality of electromagnetic wave sources, a modulator that provides different modulations to a plurality of electromagnetic waves formed from the plurality of electromagnetic wave sources, and an irradiation unit that irradiates different portions of the sample with the plurality of modulated electromagnetic waves. A detector for detecting a plurality of electromagnetic waves modulated by the sample; and a detector for performing a correlation operation between the detected plurality of electromagnetic waves and a predetermined code pattern.
The electromagnetic wave can be light of a plurality of wavelengths in the visible to infrared region. Then, it can be configured to irradiate light of a plurality of wavelengths by modulating them with different code patterns. The modulation is realized, for example, by performing a switching operation between light output and light output according to a code pattern. A Walsh code or a pseudo-noise code (PN code: Poseudo Noise code) can be used as the code pattern. As the sample, a scatterer that scatters light is suitable. A configuration may be adopted in which light passing through the inside of the scatterer is detected from a plurality of portions of the scatterer and imaged.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(First embodiment)
FIG. 1 is a block diagram showing the configuration of the imaging apparatus according to the first embodiment and the arrangement of light irradiation / detection positions. Reference numerals 101 to 104 denote light irradiation devices that modulate with different code patterns C1 to C4, reference numeral 105 denotes light passing through the inside of the scatterer, and reference numeral 106 denotes a light receiving unit. 107 is a schematic plan view showing a relationship among a light irradiation position, a detection position, and a measurement position. In the present invention, in order to solve the problem of the crosstalk, light modulated by a different code pattern for each irradiation position is irradiated according to the configuration shown in FIG. For example, at the “irradiation position 1”, “irradiation position 2”, and “irradiation position 3” shown in FIG. 2, light modulated by the code patterns C1, C2, and C3 is emitted. At this time, a code pattern used in each position has a high autocorrelation and is orthogonal to each other or has a small cross-correlation. In this case, when light is detected at the “detection position 2”, the detection light is converted into an electric signal by a photodetector, for example, a photomultiplier tube or a photodiode, and the phase is synchronized with the irradiation timing at the irradiation position 2. By performing a correlation operation between the same code pattern as used in the irradiation position 2 and the obtained electric signal, only the detected light amount of the light irradiated from the “irradiation position 2” is calculated by using the “irradiation position 1” and the “irradiation position 1”. It is possible to selectively measure separately from the light irradiated from “irradiation position 3”.
[0017]
FIG. 7 is a principle diagram for explaining the operation principle of the embodiment of FIG. 101 is a light irradiation device that modulates with the code pattern C1, 105 is light passing through the inside of the scatterer, and 106 is a light receiving unit. 701 is a signal after photoelectric conversion of the received light, 702 is a code pattern C1 used for modulation at the irradiation position 1, 703 is a correlation operation between the code pattern C1 and the received signal, 704 is a code pattern used for modulation at the irradiation position 2 C2 and 705 are correlation operations between the code pattern C2 and the received signal.
Hereinafter, the principle by which light from a desired irradiation position can be selectively measured will be described in detail.
[0018]
For simplicity, it is assumed that the irradiation position is one point. From the “irradiation position 1”, the light source is modulated with a code pattern having a cycle of “0101” of 4. The simplest way to modulate the light source with a code pattern is to make the code patterns "0" and "1" correspond to the light source outputs "off" and "on", respectively. This is a technique called OOK (On / Off Keying) in wireless communication. The light from the "irradiation position 1" passes through the inside of the scatterer and is received by the light receiving section. When this light is photoelectrically converted, a signal of “−1, +1, −1, +1” is obtained (in this example, there is no noise or level deterioration due to passing through the inside of the scatterer). Next, a correlation operation between the converted signal and a code pattern corresponding to an irradiation position to be measured is performed. Since the code pattern “0101” is a logical value of “0” or “1”, it is first converted to a level of “−1” or “+1”, and the correlation between this and the received signal is calculated. Then, “(−1) × (−1) + (+ 1) × (+1) + (− 1) × (−1) + (+ 1) × (+1) = 4” is a high correlation value at all timings. Is obtained (703). This value is a value obtained by detecting light emitted from “irradiation position 1”. By the way, in the example of FIG. 7, since no light irradiation is performed from the “irradiation position 2”, nothing should be taken out even if the correlation calculation with the code pattern corresponding to the “irradiation position 2” is performed in the light receiving unit. is there. When the correlation operation between the same received signal “−1, +1, −1, +1” and the code pattern “0011” corresponding to “irradiation position 2” is actually performed, “(−1) × (−1) ) + (+ 1) × (−1) + (− 1) × (+1) + (+ 1) × (+1) = 0 ”, and the correlation between the received signal and the signal at“ irradiation position 2 ”= 0, that is, , It is measured that there is no signal from “irradiation position 2” (705). In this way, by irradiating the modulated light with the code patterns orthogonal to each other on the irradiation side, the light from the respective irradiation positions can be separated and detected independently from each other by the correlation operation in the light receiving unit. .
[0019]
FIG. 8 is a diagram for explaining the operation principle of separating light from a plurality of irradiation positions. Reference numeral 801 denotes a light irradiation device that irradiates the irradiation position 1 with modulation by the code C1, 802 denotes a light irradiation device that irradiates the irradiation position 2 with the modulation by the code C1, and 803 denotes light level degradation and multiplexing inside the scatterer. , 804 denotes a received light, 805 denotes a signal after photoelectric conversion of the received light, 806 denotes a correlation operation by a code C1 corresponding to the irradiation position 1, and 807 denotes a correlation operation by a code C2 corresponding to the irradiation position 2. Here, it is assumed that there are two irradiation positions and light is simultaneously irradiated from the two irradiation positions. As shown in FIG. 7, the modulation method using the code pattern is easily realized by turning on and off the light source using the code pattern. FIG. 8 Irradiates from “irradiation position 1” and “irradiation position 2”, and the signal from “irradiation position 1” degrades to 1 level and the signal from “irradiation position 2” degrades to 3 level due to the inside of the scatterer. That is, an example is shown in which the light receiving unit receives light in a state where the signal level from “irradiation position 2” is three times stronger (803). The light receiving section receives the light shown in (804) because these are multiplexed. When a logical value of 0 to 4 is converted into a signal of −2 to +2 by photoelectric conversion, a signal shown in (805) is obtained. Correlation calculation is performed using this and code patterns corresponding to “irradiation position 1” and “irradiation position 2” (806, 807). The correlation calculation method is the same as before. Then, the correlation value with the code pattern corresponding to “irradiation position 1” = 2, and the correlation value with the code pattern corresponding to “irradiation position 2” = 6. It can be understood that a state where the signal level of the signal is three times as large as that of the “irradiation position 1” is certainly detected. As described above, the light source is modulated by the code pattern, and the light from the desired irradiation position can be separated and detected in principle by the correlation operation on the receiving side.
[0020]
Furthermore, when performing spectral measurement using a plurality of wavelengths as irradiation light for quantitative measurement of the pigment concentration of hemoglobin, cytochrome aa3, and myoglobin, a different code pattern is assigned to each wavelength used for irradiation. Then, by performing a correlation operation for each code pattern with respect to the light of different wavelengths irradiated to the same position, the light of a plurality of wavelengths can be reflected by optical filters, diffraction gratings, prisms, etc. Electrical spectroscopic measurement can be performed without using optical spectroscopic means involving loss.
[0021]
When this modulation method is used, the light detected at “detection position 2” is irradiated not only at the light from “irradiation position 2” but also at “irradiation position 1” and “irradiation position 3”. The amount of light detected can also be measured. This advantage relates to efficient light irradiation / detection point arrangement, which will be described in detail below. When a specific irradiation position and a detection position are exclusively assigned to each measurement position for a plurality of measurement positions, that is, for example, as shown in FIG. Each requires three places.
[0022]
FIG. 4 is a plan view showing an efficient light irradiation / detection position arrangement in the present invention. Here, as shown in FIG. 4, when the irradiation position and the detection position are alternately arranged in a grid pattern so that they can be shared by a plurality of measurement positions, the irradiation position and the detection position are each only two positions, and four irradiation positions and detection positions are required. Measurement position can be set. Here, the light at “irradiation position 1” and “irradiation position 2” having different modulation frequencies are independently obtained from the light measured at “detection position 1” in FIG. , It is possible to simultaneously measure “measurement position 1” and “measurement position 2”. Similarly, for the light measured at the “detection position 2”, the light at the “irradiation position 1” and the “irradiation position 2” having different code patterns are respectively measured by the correlation calculation, thereby obtaining the “measurement position 3”. And "measurement position 4" can be measured at the same time. As described above, the number of irradiation positions (i.e., the number of associated light sources) and the number of detection positions (i.e., the number of associated detectors) can be significantly reduced, and system efficiency is improved.
(Second embodiment)
There are various modulation methods using a code pattern at the irradiation position in the present invention, such as a method of rotating the phase according to the code pattern. However, in the case of light having a high frequency band, OOK (On / Off) is used to simplify the device configuration. Keying) is used.
(Third embodiment)
In the code pattern used in the irradiation position and the light receiving unit according to the present invention, since light at other irradiation positions is separated and detected, the properties of the code are that the autocorrelation is high and the cross-correlation is low or the cross-correlation is zero; Are desirably orthogonal. In addition, since the same pattern as the code pattern used at the irradiation position needs to be generated in the light receiving unit, it is desirable that the generation method be somewhat simple. From these viewpoints, a Walsh code having orthogonality or a pseudo noise code (PN code: Posudo Noise code) having low cross-correlation is used as the code pattern used in the irradiation position and the light receiving unit in the present invention.
[0023]
【The invention's effect】
Advantageous Effects of Invention According to the present invention, it is possible to efficiently and temporally and systematically and efficiently and compactly measure an image of information inside a living body in a wide space area with high resolution.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration and a light irradiation / detection position arrangement of an imaging device according to a first embodiment of the present invention.
FIG. 2 is a plan view illustrating the arrangement of irradiation positions, detection positions, and measurement positions in optical measurement.
FIG. 3 is a cross-sectional view showing light propagation in a scatterer in optical measurement.
FIG. 4 is a plan view showing an efficient light irradiation / detection position arrangement in the present invention.
FIG. 5 is a block diagram illustrating a configuration of an imaging device based on time switching and an arrangement of light irradiation / detection positions.
FIG. 6 is a block diagram showing a configuration of an imaging device using a plurality of modulation frequencies and a light irradiation / detection position arrangement.
FIG. 7 is a principle diagram illustrating an operation principle of the first embodiment according to the present invention.
FIG. 8 is a diagram illustrating an operation principle of separating light from a plurality of irradiation positions according to the first embodiment of the present invention.
[Explanation of symbols]
101: a light irradiation device 102 modulated by a code pattern C1 according to the present invention 102: a light irradiation device 103 modulated by a code pattern C2 according to the present invention 103: a light irradiation device 104 modulated by a code pattern C3 according to the present invention Light irradiation device 105 modulated by code pattern C4 according to the present invention 105 Light passing through the inside of scatterer 106 Configuration of light receiving section 501 according to the present invention Light irradiation device by time switching (light irradiation at time T1)
502: Light irradiation device by time switching (light irradiation at time T2)
503: Light irradiation device by time switching (light irradiation at time T3)
504: Light irradiation device by time switching (light irradiation at time T4)
505: Light passing through the inside of the scatterer 506: Configuration of the light receiving unit by time switching 507: Specification of irradiation position by time switching 508: Light irradiation / detection arrangement by time switching 601: Light irradiation device (modulation) by multiple modulation frequencies Light irradiation at frequency F1)
602: Light irradiation device using a plurality of modulation frequencies (light irradiation at modulation frequency F2)
603: Light irradiation device using a plurality of modulation frequencies (light irradiation at modulation frequency F3)
604: Light irradiation device using a plurality of modulation frequencies (light irradiation at modulation frequency F4)
Reference numeral 605: light passing through the inside of the scatterer 606: configuration of a light receiving unit using a plurality of modulation frequencies 607: specification of an irradiation position using a plurality of modulation frequencies 608: light irradiation / detection arrangement diagram 701: photoelectric conversion of received light Rear signal 702: code pattern C1 used for modulation at irradiation position 1
703: Correlation operation between code pattern C1 and received signal 704: Code pattern C2 used for modulation at irradiation position 2
705: Correlation calculation 801 between the code pattern C2 and the received signal 801: A light irradiation device 802 irradiated from the irradiation position 1 with modulation by the code C1, and a light irradiation device 803 irradiated from the irradiation position 2 with the modulation by the code C1. Degradation and multiplexing of light level inside the scatterer 804: received light 805: signal after photoelectric conversion of received light 806: correlation operation 807 by code C1 corresponding to irradiation position 1: code C2 corresponding to irradiation position 2 Correlation operation by.

Claims (8)

Generate different code patterns,
Generating an electromagnetic wave modulated with the different code pattern,
Irradiating the electromagnetic wave to a plurality of portions of the sample,
Detecting electromagnetic waves passing through the inside of the sample from a plurality of locations of the sample,
Performs a correlation operation with the code pattern on electromagnetic waves obtained from a plurality of locations on the sample,
A measurement method for obtaining information on the sample based on the result of the correlation operation. Multiple electromagnetic sources,
A modulator that gives different modulations to a plurality of electromagnetic waves formed from the plurality of electromagnetic wave sources,
An irradiator that irradiates the plurality of modulated electromagnetic waves to different portions of the sample,
A detector for detecting the plurality of electromagnetic waves modulated by the sample,
A detector that performs a correlation operation between the plurality of detected electromagnetic waves and a predetermined code pattern,
A measuring device having: In an apparatus that irradiates light of a plurality of wavelengths in the visible to infrared region to a plurality of portions of the scatterer, and detects light passing through the inside of the scatterer from the plurality of portions of the scatterer to form an image,
A means for generating a different code pattern and irradiating the modulated light with the different code pattern for each of a plurality of parts, and a means for performing a correlation operation between the transmitted light obtained at the plurality of detection parts and the code pattern. An apparatus for imaging the inside of a scatterer by light, characterized in that the information inside the scatterer corresponding to the irradiation position and the detection position is imaged. The imaging device according to claim 3,
A scatterer internal imaging device using light, characterized in that the plurality of wavelengths of light irradiating the scatterer are modulated with different code patterns for irradiation. The imaging device according to claim 3 or 4,
It is characterized in that the signal of the corresponding wavelength and light irradiation position is separated from the transmitted light obtained at the detection site by correlation calculation with the code pattern corresponding to the wavelength and light irradiation position. , A scatterer internal imaging device by light. The imaging device according to any one of claims 3 to 5,
When the light of a plurality of wavelengths to be radiated to the scatterer is modulated by different code patterns and irradiated, the modulation by the code pattern is realized by switching between light output / no light output according to the code pattern. A scatterer internal imaging device using light, characterized in that: The imaging device according to any one of claims 3 to 6,
When irradiating the scatterer with light of a plurality of wavelengths by modulating the light with different code patterns, the code patterns are different for each irradiation position, and the properties of each code have high autocorrelation and zero cross-correlation. Alternatively, an apparatus for imaging the inside of a scatterer by light, characterized by using a low object. The imaging device according to claim 7,
When irradiating a plurality of wavelengths of light to the scatterer with modulation with different code patterns, the light is characterized by using a Walsh code or a pseudo noise code (PN code: Poseudo Noise code) as the code pattern. , A scatterer internal imaging device by light.

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