JP2015019732A - Subject information acquisition device, controlling method thereof and acoustic signal acquisition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a subject information acquisition device which acquires a two-dimensional sound pressure distribution at a high sampling rate when receiving an acoustic signal using a Fabry-Perot type probe.SOLUTION: A subject information acquisition device includes: a Fabry-Perot type interferometer 105 on which an elastic wave from a subject is incident; an array light source 106 which includes a plurality of light emitting elements capable of controlling the wavelength of pulse light to be emitted; a control part 108 which controls the array light source 106; a photodiode 109 which detects reflection light obtained by reflecting the pulse light emitted from the array light source 106 by the Fabry-Perot type interferometer 105; and a processing part 110 which obtains intensity of the elastic wave by using reflection light intensity detected by the photodiode 109 to generate subject information indicating characteristics of the subject on the basis of the intensity of the elastic wave. The control part 108 makes the plurality of light emitting elements sequentially irradiate the Fabry-Perot type interferometer 105 with the pulse light at time intervals. The processing part 110 obtains time division data of the reflection light intensity on the basis of the time intervals.

Description

  The present invention relates to an object information acquisition apparatus, a control method thereof, and an acoustic signal acquisition apparatus.

  In general, imaging apparatuses using X-rays, ultrasound, and MRI (nuclear magnetic resonance method) are widely used in the medical field. On the other hand, research on optical imaging technology that obtains in-vivo information by actively propagating light emitted from a light source such as a laser into a subject such as a living body and detecting the propagating light is actively promoted in the medical field. It has been. As one of such optical imaging techniques, photoacoustic imaging has been proposed.

In photoacoustic imaging, a subject is irradiated with pulsed light from a light source, and acoustic waves generated from living tissue that absorbs the energy of light propagated and diffused in the subject are detected and analyzed at multiple locations. This is a technique for visualizing information related to optical property values inside a subject. Thereby, an optical characteristic value distribution in the subject, particularly a light energy absorption density distribution is obtained.
Examples of the acoustic wave detector include a transducer using a piezoelectric phenomenon and a transducer using a change in capacitance. In recent years, detectors using optical resonance have been developed (Non-Patent Document 1).

A structure that resonates light between two parallel reflectors is called a Fabry-Perot interferometer. An acoustic wave detector using a Fabry-Perot interferometer is called a Fabry-Perot probe. The Fabry-Perot probe has a structure in which two mirrors sandwich a polymer film. When an elastic wave is incident on this structure, the mirror on the side on which the elastic wave is incident is deformed in the film thickness direction of the polymer film, and the distance between the two mirrors (hereinafter referred to as the cavity length) changes. An elastic wave can be detected by detecting a change in reflectance that occurs at this time using measurement light.
At this time, the area irradiated with the measurement light for measuring the reflectance is the reception area. The reception area corresponds to the size of one element of the piezoelectric probe. Since the Fabry-Perot probe has a wide band and can suppress a decrease in sensitivity when the reception area is further reduced, high-resolution imaging is possible.

By the way, when putting an imaging apparatus into practical use, it is important to perform imaging in a short time. When the subject is a living body, particularly in a medical field, it is necessary for practical use to perform imaging in a short time and reduce the burden on the subject.
In order to perform imaging in a short time, it is necessary to acquire data in a short time. In order to acquire two-dimensional distribution data of photoacoustic waves, if a single probe is raster scanned, it takes a lot of time to acquire the data.
Therefore, in the detector using the resonance of light, in order to collect the two-dimensional distribution of the elastic wave at once, the sound of the ultrasonic wave irradiated to the Fabry-Perot interferometer using a CCD camera as a two-dimensional array type sensor. There is also a report example of detecting pressure (Non-Patent Document 2).

Here, a semiconductor laser called a vertical-cavity surface-emitting laser (VCSEL) will be described. A normal edge-emitting semiconductor laser emits light from the end face of its substrate, whereas a VCSEL emits light in a direction perpendicular to the substrate. Since the volume of the active layer can be reduced by the progress of its structure and processing process, it operates at a low threshold and has the features of low power consumption. In addition, the time constant of the internal temperature rise is small and the response is fast. There is also an example in which this is two-dimensionally arranged on a semiconductor substrate (Patent Document 1). Hereinafter, one laser (one light emitting point) among the lasers arrayed two-dimensionally or one-dimensionally in this way is referred to as a light-emitting element.

  Since the cavity length of the Fabry-Perot probe varies, it is necessary to change the wavelength of the measurement light according to the position on the Fabry-Perot probe in order to keep the sensitivity optimal. Since the VCSEL arranged two-dimensionally can be driven independently for each light emitting element, the wavelength of the emitted light can be controlled for each light emitting element. That is, by using a VCSEL array and a two-dimensional array type sensor, it is possible to correct a variation in the cavity length and collectively acquire a two-dimensional elastic wave distribution.

US Patent Application Publication No. 2009/0135872

E. Zang, J. Laufer, and P. Beard, “Backward-mode multiwavelength photoacoustic scanner using a planer Fabry-Perot polymer film ultrasound sensor for high-resolution three-dimensional imaging of biological tissue”, Applied Optics, 47, 4. (2008) M. Lamont, P. Beard, “2D imaging of ultrasound fields using CCD array to map output of Fabry-Perot polymer film sensor”, Electronics Letters, 42, 3, (2006)

  However, the current frame rate of a two-dimensional array sensor such as a CCD or CMOS is as fast as about 1 MHz, and cannot satisfy the sampling rate necessary for receiving high-frequency ultrasonic waves. In Non-Patent Document 2, the sampling light is pulsed and the time for irradiating the Fabry-Perot interferometer is shifted for each frame, thereby substantially improving the sampling rate. In this method, however, it is necessary to acquire a plurality of frames. is there. In addition, these high-speed two-dimensional array type sensors are very expensive and difficult to implement.

  The present invention has been made in view of the above problems, and an object thereof is to acquire a two-dimensional sound pressure distribution at a high sampling rate when receiving an acoustic signal using a Fabry-Perot probe. .

The present invention employs the following configuration. That is,
A Fabry-Perot interferometer including a first reflecting surface on which an elastic wave from the subject is incident, and a second reflecting surface;
An array light source including a plurality of light emitting elements capable of controlling the wavelength of irradiated pulsed light;
A control unit for controlling the array light source;
A photodiode for detecting reflected light reflected from the Fabry-Perot interferometer by the pulsed light emitted from the array light source;
A processing unit that determines the intensity of the elastic wave using the reflected light intensity detected by the photodiode, and generates object information indicating the characteristics of the object based on the intensity of the elastic wave;
Have
The control unit sequentially irradiates the Fabry-Perot interferometer with pulsed light at a time interval from the plurality of light emitting elements,
The processing unit obtains time division data of the reflected light intensity based on the time interval, constructs reflected light intensity change data for each light emitting element from the time division data, and uses the reflected light intensity change data. An object information acquiring apparatus that generates the object information.

The present invention also employs the following configuration. That is,
A Fabry-Perot interferometer including a first reflecting surface on which an elastic wave is incident and a second reflecting surface;
An array light source including a plurality of light emitting elements capable of controlling the wavelength of irradiated pulsed light;
A control unit for controlling the array light source;
A photodiode for detecting reflected light reflected from the Fabry-Perot interferometer by the pulsed light emitted from the array light source;
A processing unit for obtaining the intensity of the elastic wave using the reflected light intensity detected by the photodiode;
Have
The control unit sequentially irradiates the Fabry-Perot interferometer with pulsed light at a time interval from the plurality of light emitting elements,
The processing unit obtains time-division data of the reflected light intensity based on the time interval, and constructs reflected light intensity change data for each light-emitting element from the time-division data. is there.

The present invention also employs the following configuration. That is,
A Fabry-Perot interferometer including a first reflecting surface on which an elastic wave from the subject is incident, and a second reflecting surface;
An array light source including a plurality of light emitting elements capable of controlling the wavelength of irradiated pulsed light;
A control unit for controlling the array light source;
A photodiode for detecting reflected light reflected from the Fabry-Perot interferometer by the pulsed light emitted from the array light source;
A processing unit that determines the intensity of the elastic wave using the reflected light intensity detected by the photodiode, and generates object information indicating the characteristics of the object based on the intensity of the elastic wave;
A method for controlling a subject information acquisition apparatus comprising:
The control unit sequentially irradiates the Fabry-Perot interferometer with pulsed light at time intervals from the plurality of light emitting elements;
The processing unit obtains the time division data of the reflected light intensity based on the time interval, constructs reflected light intensity change data for each light emitting element from the time division data, and the reflected light intensity change Generating the subject information using data;
A control method for a subject information acquiring apparatus.

  According to the present invention, when receiving an acoustic signal using a Fabry-Perot probe, a two-dimensional sound pressure distribution can be obtained at a high sampling rate.

FIG. 2 is a diagram illustrating a device configuration according to the first embodiment. The figure which shows an example of a structure of a VCSEL array. The figure which shows an example of the structure of a Fabry-Perot type | mold probe. The time chart which shows an example of the signal reception by an imaging device. 3 is a flowchart showing processing in the first embodiment. FIG. 4 is a diagram illustrating a device configuration of a second embodiment. 9 is a flowchart showing processing in the second embodiment. FIG. 5 is a diagram illustrating an apparatus configuration of a third embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described below should be changed as appropriate according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the following description.

  The subject information acquisition apparatus of the present invention transmits an acoustic wave such as an ultrasonic wave to the subject, receives a reflected wave (echo wave) reflected and propagated inside the subject, and uses the subject information as image data. Includes an imaging device that uses ultrasonic echo technology to acquire. In addition, an imaging apparatus using a photoacoustic effect that receives acoustic waves generated and propagated in the subject by irradiating the subject with light (electromagnetic waves) and acquiring subject information as image data is included.

  In the case of the former apparatus using the ultrasonic echo technique, the acquired object information is information reflecting the difference in acoustic impedance of the tissue inside the object. In the case of an apparatus using the latter photoacoustic effect, the acquired object information is derived from the source distribution of acoustic waves generated by light irradiation, the initial sound pressure distribution in the object, or the initial sound pressure distribution. Light energy absorption density distribution, absorption coefficient distribution, and concentration distribution of substances constituting the tissue are shown. The substance constituting the tissue is, for example, a blood component such as an oxygen saturation distribution or an oxidized / reduced hemoglobin concentration distribution, or fat, collagen, moisture, and the like.

The acoustic wave referred to in the present invention is typically an ultrasonic wave and includes an elastic wave called a sound wave or an acoustic wave. An acoustic wave generated by the photoacoustic effect is called a photoacoustic wave or an optical ultrasonic wave. The apparatus of the present invention receives an acoustic wave generated or reflected in a subject by an acoustic wave detector such as a probe and propagated.
The measurement light in the present invention is a concept including incident light incident on a Fabry-Perot interferometer and reflected light guided to a photodiode by the Fabry-Perot interferometer. The measurement light is distinguished from the excitation light that irradiates the subject in order to generate an acoustic wave using the photoacoustic effect.

In the following description, an imaging apparatus that generates an image based on an acoustic signal will be described as a representative example of the subject information acquisition apparatus. However, the present invention can also be applied to an apparatus that does not generate or display an image but stores it as data based on acoustic waves.
Further, in the following object information acquisition apparatus (imaging apparatus), a portion that detects an acoustic wave is particularly referred to as an acoustic signal acquisition apparatus. The present invention can also be understood as relating to an acoustic signal acquisition device. The present invention can also be understood as a method for controlling these devices.

<Embodiment 1>
A preferred embodiment of the present invention will be described with reference to the drawings.

(Device configuration)
FIG. 1 shows a configuration example of an imaging apparatus according to this embodiment.
The imaging apparatus of this embodiment includes an excitation light source 101. The excitation light source 101 irradiates the subject 102 with excitation light 103. As a result, the photoacoustic wave 104 is generated when the light absorber inside or on the surface of the subject absorbs part of the light energy. Examples of the light absorber inside the subject include tumors and blood vessels.

A region surrounded by a broken line in the imaging device is the acoustic signal acquisition device 113. The acoustic signal acquisition device 113 includes a Fabry-Perot probe 105 for detecting the photoacoustic wave 104. The Fabry-Perot probe 105 can detect the sound pressure of the photoacoustic wave 104 by being irradiated with the measurement light 107 from the array light source 106 which is a measurement light source.
In addition, the control unit 108 in FIG. 1 controls the number n of light emitting elements used by the array light source 106, the emission timing of the measurement light 107 emitted from the array light source 106, the pulse width, and the wavelength in each light emitting element.

  The acoustic signal acquisition device 113 also includes a photodiode 109 (PD) for measuring the amount of reflected light of the measurement light 107 incident on the Fabry-Perot probe 105 and converting it into an electrical signal. Furthermore, a processing unit 110 is provided for reconstructing the time-division data of the reflected light amount obtained in the photodiode 109 into reflected light intensity change data for each light emitting element. The above are the basic components of the acoustic signal acquisition device 113.

  An imaging apparatus is configured by adding a display unit 111 to the acoustic signal acquisition apparatus 113. The processing unit 110 performs signal processing such as analysis on the reflected light intensity change data for each reconstructed light emitting element to configure subject information such as an optical characteristic value distribution, and generates image data. The display unit 111 displays the subject information obtained by the processing unit. The above is the basic configuration of the imaging apparatus including the acoustic signal acquisition apparatus of the present embodiment.

(VCSEL array)
The array light source 106 includes a one-dimensional array laser or a two-dimensional array laser. As the array light source 106, it is preferable to use a variable wavelength laser capable of emitting different or the same wavelength for each element or a plurality of elements. By making the wavelength controllable for each element, it is possible to cope with variations in cavity length (distance between mirrors). In order to increase the change in reflectance when acoustic waves enter the Fabry-Perot probe 105, it is desirable that the array light source 106 operate in a single mode.
In addition, it is desirable that the wavelength of the array light source 106 be changed at least in a wavelength range equal to or larger than the FSR (Free Spectrum Range) of the Fabry-Perot probe 105. FSR is a wavelength interval between adjacent resonance wavelengths.
Further, it is preferable that the wavelength of the array light source 106 can be changed in a short time.

A surface emitting laser (VCSEL) array can be used as an array light source that satisfies the above conditions.
FIG. 2 shows a configuration example of the VCSEL array. The array light source 106 composed of a VCSEL array is configured by arranging a total of 16 elements of a VCSEL 202 on a GaAs semiconductor substrate 201, 4 elements in a vertical direction and 4 elements in a horizontal direction. Wiring (not shown) for supplying current to each VCSEL is formed on the GaAs semiconductor substrate 201. Although FIG. 2 shows a VCSEL array having 16 light emitting elements, the number and arrangement of the light emitting elements may be determined according to the measurement range and resolution.

The measurement light 107 emitted from the array light source 106 is pulsed light. At this time, it is preferable that the pulse width can be shortened to 1 ns or less. The rise time of the array light source 106 is preferably 1 ns or less.
Further, when pulse light emission is sequentially performed between different light emitting elements, it is preferable that switching of element light emission can be performed in about several ns.

(Fabry-Perot probe)
The cross-sectional structure of the Fabry-Perot probe in this embodiment will be described with reference to FIG. As a material of the first mirror 301 and the second mirror 302, a dielectric multilayer film or a metal film can be used. The first mirror and the second mirror correspond to the first reflecting surface and the second reflecting surface of the present invention, respectively. A spacer film 303 exists between the mirrors. The spacer film 303 is preferably one having a large distortion when an elastic wave is incident on a Fabry-Perot probe. For example, an organic polymer film is used. Parylene, SU8, polyethylene or the like can be used as the organic polymer film. However, an inorganic film may be used as the spacer film 303 as long as it is a film that deforms in the film thickness direction when a sound wave is received.

  However, when the organic polymer film is formed, the film thickness tends to vary. When there is variation in the cavity length, in order to keep the acoustic wave reception sensitivity within the probe surface constant, the wavelength of the measurement light is adjusted to correspond to the variation in the cavity length within the probe surface. Must be adjusted for each position. In order to further increase the reception sensitivity, it is preferable to match the wavelength of the measurement light so that the reception sensitivity of the acoustic wave in the probe plane is maximized at each position.

The entire Fabry-Perot probe is protected by a protective film 304. As the protective film 304, an organic polymer film such as parylene or an inorganic film such as SiO ₂ formed into a thin film is used. Glass or acrylic can be used for the substrate 305 on which the second mirror 302 is formed. At this time, the substrate 305 is preferably wedge-shaped in order to reduce the influence of light interference inside the substrate. Furthermore, in order to avoid reflection of light on the surface of the substrate 305, it is preferable to perform an AR coating treatment 306.

  When an acoustic wave enters the Fabry-Perot probe from the protective film 304 side, the first mirror 301 is deformed, and the first mirror 301 and the second mirror 302 are deformed in the film thickness direction at this time. And the distance changes.

(Optical member)
The photodiode 109 can use Si or InGaAs as a receiving element depending on the wavelength of the measurement light. The photodiode 109 preferably has a fast rise time. For example, the rise time is preferably about 1 ns. The electric signal from the photodiode 109 is preferably amplified using an amplifier. However, any other optical sensor can be used as long as it can measure the amount of reflected light of the measurement light 107 when the photoacoustic wave 104 enters the Fabry-Perot probe 105 and convert it into an electrical signal.

  A half mirror 114 is used to guide the measurement light 107 to the Fabry-Perot probe 105 and the photodiode 109 which is an optical sensor. These may be configured so that the amount of reflected light in the Fabry-Perot probe 105 can be measured. Instead of the half mirror 114, a polarizing mirror and a wave plate may be used.

An optical system 115 is used to guide the measurement light 107 emitted from the array light source 106 to the Fabry-Perot probe 105. The optical system 115 is configured so that each light emitting element and the irradiation position on the Fabry-Perot interferometer have a one-to-one correspondence. The optical system 115 is configured such that the focus of the measurement light 107 is a Fabry-Perot interferometer. Further, it is preferable that the measurement light 107 is incident on the Fabry-Perot interferometer perpendicularly.
A telecentric lens can be considered as such an optical system 115. Telecentric lenses with various magnifications can be used depending on the measurement range and resolution.
Thereby, each light emitting element of the VCSEL array 106 and the irradiation position on the Fabry-Perot probe have a one-to-one correspondence.

  Further, an optical system 116 is used to guide the measurement light 107 reflected by the Fabry-Perot probe 105 to the photodiode 109. As the optical system 116, a convex lens, an objective lens, a telecentric lens, or the like can be used.

(Waveform measurement process)
FIG. 4 is a time chart showing the relationship between the pulse width and emission timing of the measurement light 107 of each light emitting element and the acoustic signal at the position where the measurement light 107 of each light emitting element is incident on the Fabry-Perot probe 105. It is an example. Waveform measurement and subsequent processing will be described with reference to this time chart and the flowchart shown in FIG.

In the following description, the number of light emitting elements to be used is n. The measurement light irradiated from each light emitting element P _i (i = 1, 2,..., N) is defined as measurement light L _i (i = 1, 2,..., N). Measuring light L _i emitted from the light emitting element is irradiated at a different position on the Fabry-Perot probe 105. Further, the positions on the Fabry-Perot probe 105 where the light from the light emitting elements P _{1 to} P _n is incident are _denoted by D _i (i = 1, 2,..., N), respectively. Furthermore, a photoacoustic signal (PA signal) at each of the positions D _{1 to} D _n is PA _i (i = 1, 2,..., N).

(Preparation stage)
First, the control unit 108 performs various settings (step S501). As setting items, first, the PA signal waveform measurement time and the number n of light emitting elements used by the array light source 106 are listed. Further, set in the light-emitting elements, light emitting timing of the measurement light 107 emitted from the array light source 106 (time interval t between the emitted from the light emitting element P _i and emitted from the light emitting element P _{i + 1),} pulse width, and wavelength To do.
At this time, the pulse width is set to be shorter than the time interval t. Furthermore, t × n is set to be equal to or less than the sampling period necessary for measurement. For example, when measuring at a sampling frequency of 10 MHz, t × n is set to be 100 ns.
When the excitation light source 101 emits excitation pulse light, a photoacoustic wave 104 is generated (step S502).

(Signal measurement stage)
Control unit 108 in accordance with the arrival of the photoacoustic wave 104 of the Fabry-Perot probe 105 above, initiates the emission and signal acquisition and measurement light 107 from the light emitting element P _i of the array light source 106. As a signal for the start of signal acquisition, for example, it can be triggered that a photodiode other than the photodiode 109 detects a part of the excitation light 103. Here, i = 1 is set in the internal counter.

In synchronization with the start of signal acquisition, the measurement light L ₁ is emitted from the light emitting element P ₁ (step S503). As a result, the photodiode 109 receives the PA signal PA ₁ at this timing at the position D ₁ on the Fabry-Perot probe 105 (step S504). Next, it waits for time t (step S507). Then, the measurement light L ₂ is emitted from the light emitting element P ₂ , and the PA signal PA ₂ at this timing at the position D ₂ on the Fabry-Perot probe 105 is received.

In this way, the measurement light L _i is emitted from the light emitting element P _i while shifting the time t, and the photodiode 109 has the PA signal PA _i at this timing at the position D _i on the Fabry-Perot probe 105. Receive. This is repeated until i = n (step S505).
This is repeated until waveform measurement of the PA signal is completed, and time-division data of the PA signal is acquired (step S506).

(Signal processing stage)
Time-division data obtained PA signal is a reflected light intensity in the element P _i that has been emitted in each time. That data represents the signal strength of the PA signal I reach the position D _i at that time. And each time t × n, by piecing together to pick up PA signal at the measurement positions _{D i,} constructing a PA signal PA _i at position _{D i} (step S508). The sampling period at this time is t × n.

Thus, by reconstructing the same signal in each of (i = 1, 2,..., N), each PA signal PA _i (in the position D _i (i = 1, 2,..., N)). i = 1, 2,..., n) can be acquired. In other words, the light reflection intensity change of each light emitting element can be acquired (step S509). By constructing an image using this, the distribution of the PA signal incident on the Fabry-Perot probe 105 is obtained (step S510). As a result, the image of the subject can be displayed on the display unit (step S511).

(Wavelength control)
In the signal measurement stage, the control unit 108 controls the injection current to the array light source 106 for each element or a plurality of elements. Thereby, the wavelength of the measurement light 107 emitted from the array light source 106 can be controlled for each element or a plurality of elements. At this time, the wavelength of each measuring beam 107 emitted from the array light source 106 is controlled according to the resonance length (or cavity length) of the light at the incident point on the Fabry-Perot probe 105. In order to individually control the wavelength, a method of controlling the element temperature of the array light source 106 for each element or a plurality of elements is also conceivable.

  The wavelength of the measuring beam 107 is preferably an optimum wavelength that maximizes the sensitivity at each position of the Fabry-Perot probe. The optimum wavelength refers to a wavelength at which the change in reflectance is maximized when an acoustic wave enters the Fabry-Perot probe 105. As a means for setting such an optimum wavelength, the control unit 108 scans the wavelength for each element or a plurality of elements, and measures the wavelength dependence of the reflectance. A method is conceivable in which each element is set to a wavelength at which the obtained reflectance change is maximum with respect to the wavelength change. For example, a method in which the absolute value of the derivative with respect to the wavelength of the reflectance is set to the largest wavelength can be considered. Such wavelength scanning is preferably performed in the preparation stage.

(Excitation light irradiation)
As the excitation light 103, light having a wavelength with a characteristic that is absorbed by a specific component among the components constituting the subject 102 is used. Pulse light can be used as the excitation light 103. The pulsed light is of the order of several pico to several hundreds of nanoseconds. When the subject is a living body, pulsed light of several nanometers to several tens of nanoseconds is suitable. The excitation light source 101 that generates the excitation light 103 is preferably a laser. However, a light emitting diode or a flash lamp may be used instead of the laser.

As the laser, various lasers such as a solid laser, a gas laser, a dye laser, and a semiconductor laser can be used. If a dye laser capable of converting the oscillation wavelength, an OPO (Optical Parametric Oscillators) laser, a titanium sapphire laser, an alexandrite laser, or the like is used, it is possible to measure a difference in optical characteristic value distribution depending on the wavelength.
Regarding the wavelength of the light source to be used, a region of 700 nm to 1100 nm that absorbs less in the living body is preferable. However, it is also possible to use a wavelength range wider than the above wavelength range, for example, a wavelength range from 200 nm to 1600 nm from ultraviolet to mid-infrared, and further terahertz waves, microwaves, and radio waves.

  In FIG. 1, the subject is irradiated with excitation light 103 from a direction that does not become a shadow of the Fabry-Perot probe 105. However, it is also possible to irradiate the excitation light 103 from the Fabry-Perot probe 105 side by using light having a wavelength that passes through the mirror of the Fabry-Perot probe 105 as the excitation light 103.

(Subject placement)
In order to efficiently detect the photoacoustic wave 104 generated from the subject 102 with the Fabry-Perot probe 105, it is desirable to use an acoustic coupling medium between the subject 102 and the Fabry-Perot probe 105. . In FIG. 1, water is used as the acoustic coupling medium, and acoustic matching is performed between the subject 102 disposed in the water tank 112 and the probe. However, the acoustic coupling medium is not limited to water. For example, an acoustic impedance matching gel may be applied between the subject 102 and the Fabry-Perot probe 105.

  Note that the water tank 112 is not used when the apparatus is used for medical purposes such as measurement using a part of the human body as a subject. In that case, an acoustic impedance matching gel is applied to the subject, that is, the affected area, and a Fabry-Perot probe 105 is placed thereon to perform imaging. The acoustic coupling medium is not limited to the matching gel, and any medium that can achieve acoustic matching between the affected area and the Fabry-Perot probe 105 may be used.

(Details of signal processing)
The Fabry-Perot probe 105 detects the photoacoustic wave 104 as a change in the amount of reflected light of the measurement light 107, and the photodiode 109 converts the change in the amount of light into an electrical signal. The processing unit 110 constructs a distribution of the PA signal incident on the Fabry-Perot probe 105 as described above from the obtained electrical signal. At this time, it is preferable to normalize using the light amount or the light amount change amount for each beam of the measurement light 107 emitted from the array light source 106. As a result, it is possible to suppress variations in reception sensitivity within the surface of Fabry-Perot probe 105.

The processing unit 110 performs image reconstruction in order to obtain subject information such as an optical characteristic value distribution from the obtained distribution of electrical signals. As a reconstruction algorithm, universal back projection or phasing addition can be employed.
Since the obtained PA signal distributions PA _i (i = 1, 2,..., N) have different emission timings, for example, the data acquisition timings of PA _i and PA _{i + 1} are t (emission and emission from the light emitting element P _i). The time interval from the emission from the element P _{i + 1} ) is shifted. Therefore, it is necessary to consider this delay time when generating data by image reconstruction.
For example, it is possible to perform reconstruction after generating data at the same time by performing linear interpolation on the obtained data of PA _i (i = 1, 2,..., N). It is also possible to perform reconstruction by treating each data of PA _i (i = 1, 2,..., N) as an average value during time t × n.

When light having a plurality of wavelengths is used as the excitation light 103, the optical coefficients in the living body are calculated for each wavelength, and those values and substances constituting the living tissue (glucose, collagen, oxidized / reduced hemoglobin) Etc.) Compare with the intrinsic wavelength dependence. Thereby, it is also possible to image the concentration distribution of the substance constituting the living body.
In the present embodiment, the processing unit 110 performs a plurality of operations such as signal reconstruction processing of reflected light intensity change data for each light emitting element and signal processing such as analysis. However, each operation is a separate component. (Information processing apparatus, calculation circuit, etc.) may be performed.
In the present embodiment, one PA signal is acquired in one process, but noise can be reduced by repeatedly performing the measurement.

  By using the imaging apparatus as described above, it is possible to obtain a sound pressure distribution (light reflection intensity distribution) at a high sampling rate by using the Fabry-Perot probe 105 and obtain a good photoacoustic image. Become. Moreover, the cost of the apparatus can be reduced.

<Embodiment 2>
A configuration example of the imaging apparatus according to the present embodiment will be described with reference to FIG. The imaging apparatus of the present embodiment acquires a sound pressure distribution at a high sampling rate using a plurality of arranged photodiodes. About the structure similar to the said embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted. Although three photodiodes 609 are arranged in FIG. 6, the number of photodiodes can be changed according to the resolution, sampling frequency, and imaging range.

  The imaging apparatus of the present embodiment detects and images the photoacoustic wave 104 generated by the excitation light 103 by the Fabry-Perot probe 105, as in the above embodiment. At that time, there are a plurality of photodiodes 609 for measuring in parallel the amount of reflected light of the measurement light 107 incident on the Fabry-Perot probe 105 and converting it into an electrical signal. Furthermore, the processing unit 110 according to the present embodiment has a function of reconstructing the time-division data of the reflected light amount obtained by the plurality of photodiodes 609 into reflected light intensity change data for each light emitting element.

The control unit 108 in FIG. 6 controls the number of light emitting elements of the array light source 106 used for each photodiode, the timing at which the measurement light 107 emitted from the array light source 106 emits light, the pulse width, and the wavelength in each light emitting element. The number of photodiodes 609 used in this embodiment and n _p, the number of elements of the light emitting elements used in each photodiode and n _l pieces. That is, the total number of light emitting elements used is n _p × n _l .

When assigning a light emitting element to each photodiode 609, it is preferable to group adjacent light emitting elements into the same photodiode. This is because the arrangement of the optical system is simpler when the reflected light of adjacent spots on the Fabry-Perot probe 105 is received by the same photodiode.
However, grouping is not limited to this. For example, although the arrangement of the optical system is complicated, the PA signal incident on the adjacent position is acquired at the same time (with no delay) by receiving the reflected light of the adjacent spot with a different photodiode. Is also possible.

Measurement light irradiated from each of the n _l light emitting elements P _ji (i = 1, 2,..., N _l ) used in each photodiode Ph _j (j = 1, 2,..., N _p ) is measured. It is assumed that light L _ji (i = 1, 2,..., N _l ). N _p × n _l measurement lights 107L _ji (i = 1, 2,..., N _l , j = 1, 2,..., N _p ) emitted from the light emitting elements are on the Fabry-Perot probe 105. N _p × n ₁ different positions are irradiated. Here, the position D _ji irradiated on the Fabry-Perot probe 105 to each of the light emitting elements P _ji (i = 1, 2,..., N _l , j = 1, 2,..., N _p ). A photoacoustic signal (PA signal) at (i = 1, 2,..., N _l , j = 1, 2,..., N _p ) is expressed as PA _ji (i = 1, 2,..., N _l , j = 1, 2,..., N _p ).

  Hereinafter, the processing of this embodiment will be described with reference to the flowchart of FIG. 7 as necessary. At that time, processing similar to that in FIG. 5 is omitted as appropriate.

(Preparation stage)
First, the control unit 108 sets the PA signal waveform measurement time, the number n _p of photodiodes used, and the number n _{l of} light emitting elements used for each photodiode. Moreover, setting the timing of emission of the measurement light 107 emitted from the array light source 106 (and emitted from the light emitting element P _ji, the time interval t between the emitted from the light emitting element P _{ji + 1),} pulse width, and the wavelength in each light emitting element (Step S701). At this time, the pulse width is shorter than t, and t × n ₁ is set to be equal to or shorter than the sampling period necessary for measurement. For example, when measuring at a sampling frequency of 10 MHz, t × n _{1 is set} to 100 ns.
The processing in step S702 is the same as that in step S502 in FIG.

(Signal measurement stage)
When the photoacoustic wave 104 arrives on the Fabry-Perot probe 105, the control unit 108 emits the measurement light 107 from the array light source 106 and starts signal acquisition. As a signal for the start of signal acquisition, for example, it can be triggered that a photodiode other than the plurality of photodiodes 609 has detected a part of the excitation light 103. Here, i = 1 is set in the internal counter.

In accordance with the start of the signal acquisition, _{n p} pieces of light emitting elements _{P j1 (j = 1,2, ...} , n p) each measuring light from the _{L j1 (j = 1,2, ...} , n p) emits ( Step S703). Thereby, in the n _p photodiodes 609, the n _p PA signals PA _j1 at this timing at the position D _j1 (j = 1, 2,..., N _p ) on the Fabry-Perot probe 105 are obtained. (J = 1, 2,..., N _p ) are received in parallel (step S704).

Next, it waits for time t (step S707). Then, _{n p} pieces of light emitting elements _{P j2 (j = 1,2, ...} , n p) from each of the measurement light _{L j2 (j = 1,2, ...} , n p) irradiating. As a result, n _p PA signals PA _j2 (j = 1, 2,..., N) at this timing at the position D _j2 (j = 1, 2,..., N _p ) on the Fabry-Perot probe 105. n _p ) are received in parallel.

In this manner, the measurement light L _ji is emitted from the light emitting element P _ji (j = 1, 2,..., N _p ) while shifting the time t. Further, the _{n p-number} of photodiodes 609, position _{D ji (j = 1,2, ...} , n p) on the Fabry-Perot probe 105 in, _{n p} number of PA signal _{PA ji} at this timing ( j = 1, 2,... n _p ) are received in parallel. This is repeated until i = n (step S705).
This is repeated until waveform measurement of the PA signal is completed, and time-division data of the PA signal is acquired (step S706).

(Signal processing stage)
The obtained time-division data of the PA signal is the reflected light intensity at P _ji (j = 1, 2,..., N _p ) emitting light at each time. That data is located in the time _{D ji (j = 1,2, ...} , n p) PA signal reaches the _{PA ji (j = 1,2, ...} , n p) represents the signal strength of the. Then, at every time t × n, the PA signal at the measured position D _ji (j = 1, 2,..., N _p ) is picked up and connected, so that the position D _ji (j = 1, 2 _,. A PA signal at n _p ) is constructed (step S708). The sampling period at this time is t × n.

Thus, by reconstructing the above-mentioned signal in each of (i = 1, 2,..., N), the position D _ji (i = 1, 2,... N ₁ , j = 1, 2,. , N _p ), each PA signal PA _ji (i = 1, 2,... N ₁ , j = 1, 2,..., N _p ) can be acquired. In other words, the light reflection intensity change of each light emitting element can be constructed (step S709).
By measuring in this way, the distribution of the PA signal incident on the Fabry-Perot probe 105 is obtained (step S710). Thereby, the image of the subject can be displayed on the display unit (step S711).

In the present embodiment, the number of light emitting elements to be used, the light emission timing, and the pulse width are the same in each photodiode. However, these numerical values are not necessarily the same and may be different for each photodiode. Further, the processing of the processing unit 110 may be shared by another component.
An optical system 116 is used to guide the measurement light 107 reflected by the Fabry-Perot probe 105 to each of the plurality of photodiodes 609. As the optical system 116, a convex lens, an objective lens, a telecentric lens, a fly-eye lens, or the like can be used.

  By using the imaging apparatus as described above, it is possible to obtain a sound pressure distribution (light reflection intensity distribution) at a high sampling rate by using the Fabry-Perot probe 105 and obtain a good photoacoustic image. Become. Moreover, the cost of the apparatus can be reduced.

<Embodiment 3>
FIG. 8 shows a configuration example of the imaging apparatus in the present embodiment.
The imaging apparatus according to the present embodiment images an acoustic impedance distribution in a living body using an ultrasonic echo technique. Detailed description of the same configurations as those in the above embodiments will be omitted.
The imaging apparatus of this embodiment includes a transducer 803 that transmits an elastic wave 802 to a subject 801 and a pulsar 813 for driving the transducer 803.

  The acoustic signal acquisition apparatus of this embodiment includes a Fabry-Perot probe 804. The Fabry-Perot probe 804 is installed for the purpose of detecting an elastic wave 805 reflected at the interface between tissues having different acoustic impedances, such as a tumor in the subject 801. However, the function of the probe itself may be the same as that of the Fabry-Perot probe 105 in FIG.

As in FIG. 1, the Fabry-Perot probe 804 can detect the sound pressure of the elastic wave 805 by being irradiated with the measurement light 807 from the array light source 806 that is a measurement light source. The functions and operations of the control unit 808, the photodiode 809 that measures the amount of reflected light, and the processing unit 810 that processes information (in this case, information on acoustic impedance) are also the same as in FIG.
The above are the basic components of the acoustic signal acquisition apparatus. An imaging apparatus is configured by adding a display unit 811 that displays acoustic impedance distribution information to the acoustic signal acquisition apparatus.

In the following description, similarly to Embodiment 1, the number of light emitting elements to be used is n. The measurement light emitted from each light emitting element P _i (i = 1, 2,..., N) is defined as measurement light L _i (i = 1, 2,..., N). Measurement light 807 emitted from each light emitting element is irradiated to different positions on the Fabry-Perot probe 804. In addition, positions on the Fabry-Perot probe 804 on which light from the light emitting elements P _{1 to} P _n is incident are _denoted by D _i (i = 1, 2,..., N), respectively. Further, an acoustic signal (US signal) at each of the positions D _{1 to} D _n is set as a US signal US _i (i = 1, 2,..., N).

(Preparation stage)
First, the control unit 808 sets the US signal waveform measurement time and the number n of light emitting elements used by the array light source 806. Further, in each light emitting element, emission timing of the measurement light 807 emitted from the array light source 806 (distance t between the emission of the light emitting element P _i and emitted from the light emitting element P _{i + 1),} set the pulse width, and wavelength .
At this time, the pulse width is set to be shorter than t. Furthermore, t × n is set to be equal to or less than the sampling period necessary for measurement. For example, when measuring at a sampling frequency of 10 MHz, t × n is set to be 100 ns.
When the pulsar 813 drives the transducer 803 and the elastic wave 802 is incident on the subject 801 in the water tank, it is reflected at a portion having a different acoustic impedance to become an elastic wave 805.

(Signal measurement stage)
The control unit 808 emits measurement light 807 from the array light source 806 and starts signal acquisition in accordance with arrival of the elastic wave 805 reflected by the subject 801 on the Fabry-Perot probe 804. For example, an output trigger from the pulser 813 can be used as a signal for starting signal acquisition.
In synchronization with the start of signal acquisition, the measurement light L ₁ is emitted from the light emitting element P ₁ . As a result, the photodiode 809 receives the US signal US ₁ at this timing at the position D ₁ on the Fabry-Perot probe 804. Next, it is shifted by time t (waiting for time t), the measurement light L ₂ is irradiated from the light emitting element P ₂ , and the US signal US at this timing at the position D ₂ on the Fabry-Perot probe 804. ₂ is received.

In this way, the measurement light L _i is emitted from the light emitting element P _i while shifting the time t, and the photodiode 809 receives the US signal US _i at this timing at the position on the Fabry-Perot probe 804. To do. This is repeated until i = n.
This is repeated until the measurement of the waveform of the US signal is completed, and time-division data of the US signal is acquired.

(Signal processing stage)
The obtained time-division data of the US signal is the reflected light intensity at the element P _i that emits light at each time. That data represents the signal strength of the US signal reaches the position D _i at that time. And each time t × n, by piecing together to pick up US signal at the measurement positions D _i, constructing a US signal at position D _i. The sampling period at this time is t × n.
Thus, by reconstructing the same signal in each of (i = 1, 2,..., N), each US signal US _i (in the position D _i (i = 1, 2,..., N)). i = 1, 2,..., n) can be acquired.

By measuring in this way, the distribution of the US signal incident on the Fabry-Perot probe 804 can be obtained. As a result, image construction and image display are possible.
As signal processing for obtaining the acoustic impedance distribution from the obtained US signal distribution, phasing addition and the like can be considered.

Since the obtained US signal distributions US _i (i = 1, 2,..., N) have different light emission timings, for example, the data acquisition timing of US _i and US _{i + 1} is t (emission from the light emitting element P _i). And the distance from the light emitting element _{Pi + 1} ). Therefore, it is necessary to consider this delay time when performing image reconstruction.
For example, the data at the same time can be reconstructed by performing linear interpolation on the obtained data of US _i (i = 1, 2,..., N).
It is also possible to perform reconstruction by treating each data of US _i (i = 1, 2,..., N) as an average value during time t × n.
Further, the processing of the processing unit 110 may be shared by another component.

Although one photodiode is used in this embodiment, a plurality of photodiodes may be used according to the sampling frequency, resolution, and imaging range as in the second embodiment.
Functions and suitable materials such as the half mirror 812, the water tank 814, or the acoustic matching material, the optical systems 815 and 816, and the like are the same as those in the above embodiment.

  By using the imaging apparatus as described above, it is possible to obtain a sound pressure distribution (light reflection intensity distribution) at a high sampling rate by using the Fabry-Perot probe 105 and obtain a good acoustic impedance distribution image. It becomes. Moreover, the cost of the apparatus can be reduced.

<Example 1>
Next, an embodiment in which the present invention is applied to actual acoustic wave acquisition will be described. The imaging apparatus of the present example has the configuration described in the first embodiment.
In this example, a sample in which an intralipid 1% aqueous solution is hardened with agar and a rubber wire having a diameter of 300 μm that absorbs light is disposed therein is used as the subject. Samples are placed in water.

  Dielectric multilayer films are used for the first mirror and the second mirror of the Fabry-Perot probe. This dielectric multilayer film is designed to have a reflectance of 95% or more in the light of 830 to 870 nm. The substrate of the Fabry-Perot probe is BK7, and the surface of the substrate opposite to the surface on which the dielectric multilayer film is formed is AR so that the reflectance is 1% or less at 830-870 nm. It has been coated. Parylene C is used for the spacer film between the mirrors, and the film thickness is 30 μm. Further, Parylene C is used as a protective film for the probe.

The measurement light source that emits the measurement light is a wavelength tunable light source. As this measurement light source, a VCSEL array capable of controlling the wavelength in the range near 850 nm is used. The number of arrays is 5 × 5 = 25 channels, and the array pitch is 1 mm.
The driving of the VCSEL is controlled by applying an input current to the VCSEL. The input current value is set so that each light emitting element emits light having a wavelength that maximizes the sensitivity of the Fabry-Perot probe. Then, pulse light is sequentially emitted from the light emitting elements by sequentially applying a pulse type input current to the 25 light emitting elements. At this time, the pulse width is set to 2 ns, the light emission interval is set to 4 ns, and pulse light is emitted sequentially from each light emitting element. The PA signal measurement time is 10 μs.

Light emitted from each element of the VCSEL array is irradiated to each position of the Fabry-Perot probe through a telecentric lens. Measurement light emitted from the 25 light emitting elements is irradiated on the Fabry-Perot probe in the vertical and horizontal directions at 1 mm intervals. That is, the measurement range is a 5 mm square area. The measurement light (reflected light) reflected by the Fabry-Perot probe is reflected by the half mirror and then enters the silicon photodiode through the convex lens.
Then, irradiation of pulsed light from the 25 light emitting elements is sequentially repeated until the waveform measurement of the PA signal is completed, and time division data of the PA signal is acquired.

The obtained time division data of the PA signal is picked up and connected for each light emitting element emitting light at each time. Thereby, it is possible to construct a PA signal at each position where the measurement light emitted from each light emitting element is incident on the Fabry-Perot probe. As a result, a PA signal that reaches each position (25 points) on the Fabry-Perot probe with a sampling period of 100 ns can be obtained.
By measuring in this way, the distribution of the PA signal incident on the Fabry-Perot probe 105 can be acquired.

In such an apparatus, the subject is irradiated with excitation light, and photoacoustic wave measurement is started. The excitation light source is a titanium sapphire laser, the repetition frequency of the emitted pulsed light is 10 Hz, the pulse width is 10 ns, and the wavelength is 797 nm. A part of the excitation light is detected by another photodiode, and this is used as a trigger for starting signal acquisition.
Thereafter, image reconstruction is performed by a universal back projection algorithm using the electrical signal distribution based on the constructed photoacoustic wave. As a result, it is possible to image a rubber wire in Intralipid 1% agar which is a light diffusion medium.

<Example 2>
The imaging apparatus of the present example has the configuration described in the second embodiment. Since the configuration of the Fabry-Perot probe of the present embodiment is the same as that of the first embodiment, detailed description thereof is omitted.
In this example, a sample in which an intralipid 1% aqueous solution is hardened with agar and a rubber wire having a diameter of 100 μm that absorbs light is disposed therein is used as a subject. Samples are placed in water.

In this embodiment, ten photodiodes are used. As a measurement light source, a VCSEL array that is variable in wavelength in the vicinity of 850 nm is used. The number of arrays is 10 × 10 100 channels, and the array pitch is 1 mm. The optical system is designed so that ten measurement beams are incident on each photodiode.
The driving of the VCSEL is controlled by applying an input current to the VCSEL. The input current value is set so that each light emitting element has a wavelength at which the sensitivity of the Fabry-Perot probe is maximized. Then, pulse light is sequentially emitted from the light emitting elements by sequentially applying a pulsed input current to the ten light emitting elements allocated to each photodiode. At this time, the pulse width is set to 2 ns, the light emission interval is set to 4 ns, and pulse light is emitted sequentially from each light emitting element. The PA signal measurement time is 10 μs.

Light emitted from each element of the VCSEL array is irradiated to each position of the Fabry-Perot probe through a telecentric lens. Measurement light emitted from 100 light emitting elements is irradiated on the Fabry-Perot probe in the vertical and horizontal directions at 1 mm intervals. That is, the measurement range is a 10 mm square region. The measurement light (reflected light) reflected by the Fabry-Perot probe is reflected by a half mirror and then enters each silicon photodiode through a convex lens.
Then, irradiation of pulse light from each of the 10 light emitting elements (total of 100) is sequentially repeated until waveform measurement of the PA signal is completed, and time-division data of the PA signal is acquired.

The time division data of the PA signal obtained in each photodiode is picked up and connected for each light emitting element emitting light at each time. Thereby, it is possible to construct a PA signal at each position where the measurement light emitted from each light emitting element is incident on the Fabry-Perot probe. As a result, a PA signal that reaches each position (100 points) on the Fabry-Perot probe with a sampling period of 40 ns can be obtained.
By measuring in this way, the distribution of the PA signal incident on the Fabry-Perot probe 105 can be obtained.

In such an apparatus, the subject is irradiated with excitation light, and photoacoustic wave measurement is started. The excitation light source is a YAG laser, and the repetition frequency of the emitted pulsed light is 10 Hz, the pulse width is 10 ns, and the wavelength is 532 nm. A part of the excitation light is detected by another photodiode, and this is used as a trigger for starting signal acquisition.
Thereafter, image reconstruction is performed by a universal back projection algorithm using the electrical signal distribution based on the constructed photoacoustic wave. As a result, it is possible to image a rubber wire in Intralipid 1% agar which is a light diffusion medium.

<Example 3>
The imaging apparatus of the present example has the configuration described in the third embodiment. Since the configurations of the Fabry-Perot probe, the optical system, and the optical sensor of this embodiment are the same as those of the first embodiment, detailed description thereof is omitted.
In this example, a polyethylene wire having a diameter of 500 μm is imaged in which a 1% aqueous solution of Intralipid is solidified with agar as a subject. The phantom is placed in the water.

The measurement light source that emits the measurement light is a wavelength tunable light source. As this measurement light source, 850 nm
A VCSEL array is used that is tunable in the vicinity. The number of arrays is 25 channels of 5 × 5, and the array pitch is 1 mm.
The driving of the VCSEL is controlled by applying an input current to the VCSEL. The input current value is set so that each light emitting element has a wavelength at which the sensitivity of the Fabry-Perot probe is maximized. Then, pulse light is sequentially emitted from the light emitting elements by sequentially applying a pulse type input current to the 25 light emitting elements. At this time, the pulse width is set to 2 ns, the light emission interval is set to 4 ns, and pulse light is emitted sequentially from each light emitting element. The measurement time of the US signal is 10 μs.
Then, irradiation of pulsed light from the 25 light emitting elements is sequentially repeated until the waveform measurement of the PA signal is completed, and time division data of the US signal is acquired.

  The obtained time division data of the US signal is picked up and connected for each light emitting element emitting light at each time. Thereby, it is possible to construct a US signal at each position where the measurement light emitted from each light emitting element is incident on the Fabry-Perot probe. As a result, a US signal that reaches each position (25 points) on the Fabry-Perot probe with a sampling period of 100 ns can be obtained.

In such an apparatus, an object is irradiated with elastic waves using a transducer having a center frequency of 3 MHz. The transducer is of a piezoelectric type and is made of PZT. The elastic wave is emitted as a pulse wave using a pulsar, and the repetition frequency of the elastic wave is 1 KHz.
Thereafter, the echo wave reflected by the elastic wave in the subject is measured by the Fabry-Perot probe. Then, using the obtained signal, the acoustic impedance distribution in the subject was imaged by a reconstruction algorithm using phasing addition. Thereby, the polyethylene wire in agar is imaged.

  As described above, it is possible to acquire an acoustic wave by applying the present invention even in an imaging apparatus using the ultrasonic echo technique.

In the present specification, the configuration example related to the biological information imaging apparatus using the living body as the subject has been mainly described. According to this, for the diagnosis of tumors and vascular diseases and the follow-up of chemical treatment, it is possible to image the distribution of optical characteristic values in the living body and the concentration distribution of the substances constituting the living tissue obtained from the information. Thus, it can be used as a medical diagnostic imaging device.
Furthermore, it is easy for those skilled in the art to apply to a non-destructive inspection for a non-biological substance as a subject. As described above, the present invention can be widely used as an inspection apparatus.

  105: Fabry-Perot probe, 106: array light source, 108: control unit, 109: photodiode, 110: processing unit

Claims (14)

A Fabry-Perot interferometer including a first reflecting surface on which an elastic wave from the subject is incident, and a second reflecting surface;
An array light source including a plurality of light emitting elements capable of controlling the wavelength of irradiated pulsed light;
A control unit for controlling the array light source;
A photodiode for detecting reflected light reflected from the Fabry-Perot interferometer by the pulsed light emitted from the array light source;
A processing unit that determines the intensity of the elastic wave using the reflected light intensity detected by the photodiode, and generates object information indicating the characteristics of the object based on the intensity of the elastic wave;
Have
The control unit sequentially irradiates the Fabry-Perot interferometer with pulsed light at a time interval from the plurality of light emitting elements,
The processing unit obtains time division data of the reflected light intensity based on the time interval, constructs reflected light intensity change data for each light emitting element from the time division data, and uses the reflected light intensity change data. A subject information acquisition apparatus that generates the subject information. The object information acquiring apparatus according to claim 1, wherein each of the light emitting elements of the array light source and the irradiation position on the Fabry-Perot interferometer have a one-to-one correspondence. The control unit determines a wavelength of the pulsed light emitted from the light emitting element based on a distance between the first reflecting surface and the second reflecting surface at an irradiation position of the Fabry-Perot interferometer corresponding to the light emitting element. The object information acquiring apparatus according to claim 2, wherein the object information acquiring apparatus is controlled. The subject information acquisition apparatus according to claim 1, wherein the control unit performs control such that a pulse width of the pulsed light is shorter than the time interval. 5. The control unit according to claim 1, wherein the control unit performs control such that a product of the time interval and the number of the light emitting elements is equal to or less than a sampling period for acquiring the reflected light intensity. 2. The subject information acquisition apparatus according to the item. The object information acquisition apparatus according to claim 1, wherein the processing unit linearly interpolates a shift due to the time interval when generating the object information. The subject information acquisition according to any one of claims 1 to 6, wherein a plurality of the photodiodes are arranged, and the plurality of light emitting elements are assigned to any one of the plurality of photodiodes. apparatus. The object information acquiring apparatus according to claim 7, wherein adjacent light emitting elements are assigned to the same photodiode. The object information acquiring apparatus according to claim 1, wherein the array light source is a VCSEL array. The object information acquiring apparatus according to claim 1, further comprising a display unit configured to display the object information. An excitation light source for irradiating the subject with excitation light;
The object information acquiring apparatus according to claim 1, wherein the elastic wave is a photoacoustic wave generated from the object irradiated with the excitation light. A transducer for transmitting an elastic wave to the subject;
The object information acquiring apparatus according to claim 1, wherein the elastic wave is a reflection of the transmitted elastic wave. A Fabry-Perot interferometer including a first reflecting surface on which an elastic wave is incident and a second reflecting surface;
An array light source including a plurality of light emitting elements capable of controlling the wavelength of irradiated pulsed light;
A control unit for controlling the array light source;
A photodiode for detecting reflected light reflected from the Fabry-Perot interferometer by the pulsed light emitted from the array light source;
A processing unit for obtaining the intensity of the elastic wave using the reflected light intensity detected by the photodiode;
Have
The control unit sequentially irradiates the Fabry-Perot interferometer with pulsed light at a time interval from the plurality of light emitting elements,
The processing unit obtains time division data of the reflected light intensity based on the time interval, and constructs reflected light intensity change data for each light emitting element from the time division data. A Fabry-Perot interferometer including a first reflecting surface on which an elastic wave from the subject is incident, and a second reflecting surface;
An array light source including a plurality of light emitting elements capable of controlling the wavelength of irradiated pulsed light;
A control unit for controlling the array light source;
A photodiode for detecting reflected light reflected from the Fabry-Perot interferometer by the pulsed light emitted from the array light source;
A processing unit that determines the intensity of the elastic wave using the reflected light intensity detected by the photodiode, and generates object information indicating the characteristics of the object based on the intensity of the elastic wave;
A method for controlling a subject information acquisition apparatus comprising:
The control unit sequentially irradiates the Fabry-Perot interferometer with pulsed light at time intervals from the plurality of light emitting elements;
The processing unit obtains the time division data of the reflected light intensity based on the time interval, constructs reflected light intensity change data for each light emitting element from the time division data, and the reflected light intensity change Generating the subject information using data;
A method for controlling a subject information acquiring apparatus, comprising:

Images