WO2008059812A1

WO2008059812A1 - Opto-acoustic measurement system

Info

Publication number: WO2008059812A1
Application number: PCT/JP2007/071961
Authority: WO
Inventors: Hiroto Tateno
Original assignee: Kagoshima University
Priority date: 2006-11-14
Filing date: 2007-11-13
Publication date: 2008-05-22
Also published as: JPWO2008059812A1; JP5555910B2

Abstract

A composite resonance frequency (ft) is determined on the basis of the amplitude of an acoustic signal which is generated from a PZT oscillator (4) by irradiating the surface (or upper face) of an object specimen (3) fixed (or adhered) to the surface (or upper face) of the PZT oscillator (4), with an intermittent light. The light emitting state of a diode array (1) is so controlled that the intermittent light of the composite resonance frequency (ft) determined may be emitted from the diode array (1). The composite resonance frequency (ft) is used to determine sound wave properties such as the sound velocity (ν), the Young's modulus (E) and the periodic damping factor (τ) of the specimen (3).

Description

Specification

Photoacoustic measurement system

Technical field

The present invention relates to a photoacoustic measurement system, and is particularly suitable for use in order to enable observation of the state of a sample to be measured using a photoacoustic effect.

Background art

In general, when intermittent excitation light (hereinafter referred to as intermittent light) is irradiated on a sample surface, a temperature change occurs on the sample surface, and a sound wave is generated. Such a phenomenon is called a photoacoustic effect, and a photoacoustic microscope has been proposed in which an image of a sample is obtained using this photoacoustic effect.

Patent Document 1 discloses a photoacoustic microscope that detects a photoacoustic wave with a microphone and displays an image (photoacoustic image) of a sample on a television monitor based on the detected photoacoustic wave.

[0003] However, the conventional technique has a problem that it is difficult to obtain detailed information of the sample because only the acoustic attenuation coefficient is captured among the acoustic wave properties.

[0004] Patent Document 1: Japanese Patent Laid-Open No. 4 213053

Disclosure of the invention

[0005] The present invention has been made in view of such problems, and an object thereof is to obtain more detailed information on a sample than in the past by using a photoacoustic effect.

[0006] The photoacoustic measurement system of the present invention is attached to a sample and detects a vibration of the sample, and a sample to which the vibration detection element is attached is irradiated with intermittent excitation light. The sample and the vibration detection based on an acoustic signal indicating the vibration of the sample detected by the vibration detection element, and a light emitting means for supplying the intermittent excitation light to the photoacoustic microscope. A frequency deriving means for obtaining an overall composite resonance frequency with the element, and a sample attached to the vibration detecting element is irradiated with the excitation light intermittently at the composite resonance frequency obtained by the frequency deriving means. As described above, it has a control means for controlling the light emitting means. Brief Description of Drawings

[0007] FIG. 1 is a diagram showing an example of the configuration of a photoacoustic measurement system according to an embodiment of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention and showing an example of a state of a sample fixed to a PZT vibrator.

FIG. 3 shows an embodiment of the present invention, and is a diagram showing an example of a frequency shift topograph in the sample shown in FIG. 2.

FIG. 4 shows an embodiment of the present invention, and is a diagram showing an example of a topography of vibration damping rates in sample 3 shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

[0008] One embodiment of the present invention will be described below.

FIG. 1 is a diagram showing an example of the configuration of the photoacoustic measurement system.

In FIG. 1, the photoacoustic measurement system includes a light emitting diode array (a plurality of light emitting diodes constituting a light emitting diode array) 1, a photoacoustic resonance microscope 20, a CCD camera 18, a monitor 17, and PZT (zirconate titanate). (Lead) vibrator 4, XY working specimen stage 5, specimen stage drive device 19, vibration detection circuit 6, tuning amplifier 7, external voltmeter 9, VF converter 11, and computer control A pulse generator 13, a diode power controller 14, a specific diode switch 15, and a PC (personal computer) 12 are provided.

A PZT vibrator 4, which is an example of a vibration detection element, is attached on the XY working sample stage 5. A sample 3 is attached and fixed to the surface of the PZT vibrator 4. FIG. 2 is a diagram showing an example of the state of the sample 3 fixed to the PZT vibrator 4. As shown in FIG. 2, in this embodiment, a case where a substantially equilateral triangular aluminum plate (aluminum adhesive tape) is used as the sample 3 is illustrated. The thickness of Sample 3 is 0.13 mm.

The sample stage driving device 19 includes an X direction sample stage driving device 19a and a Y direction sample stage driving device 19b. The X-direction sample stage drive device 19a is for moving the XY operation sample stage 5 in the X-axis direction (lateral direction toward FIG. 1). The Y-direction sample stage driving device 19b is for moving the XY working sample stage 5 in the Y-axis direction (depth direction in FIG. 1). These X direction sample stage drive unit 19a and Y direction sample stage drive unit 19b are, for example, a no-less motor. And receiving the control signal transmitted from the PC 12 and operating the pulse motor based on the received control signal to drive the XY operation sample stage 5.

The photoacoustic resonance microscope 20 includes a half mirror 2. When intermittent light having a beam diameter of, for example, about 50 m is emitted from the light emitting diode array 1, the intermittent light is transmitted to the half mirror. Irradiate sample 3 via 2. Then, the light signal excited on the surface of the sample 3 passes through the inside of the sample 3 and strikes the surface of the PZT vibrator 4. As a result, periodic pressure changes occur in the PZT vibrator 4 and the surrounding gas, and sound waves are generated.

[0012] When the sample 3 is irradiated with intermittent light, reflected light is generated from the sample 3. This reflected light is taken into the CCD camera 18 through the half mirror 2. The CCD camera 18 generates image data of the sample 3 based on the captured reflected light, and displays the generated image data on the monitor 17. The monitor 17 is, for example, an LCD (Liquid Crystal Display). In addition to the half mirror 2, a lens 21 for irradiating the sample 3 with intermittent light, a lens 22 for guiding the intermittent light to the half mirror 2, and the like are also provided inside the photoacoustic resonance microscope 20. Yes.

[0013] The PZT vibrator 4 is a piezoelectric element. Therefore, when the signal force of light excited on the surface of the sample 3 fixed to the PZT vibrator 4 passes through the inside of the sample 3 and hits the surface of the PZT vibrator 4, the PZT vibrator 4 vibrates. Then, an electrical signal (ie, an acoustic signal) corresponding to the vibration is generated (detected).

The vibration detection circuit 6 is a circuit for amplifying the acoustic signal generated by the PZT vibrator 4. Specifically, the vibration detection circuit 6 is a current amplification circuit including a positive feedback circuit. Since the vibration detection circuit 6 includes a positive feedback circuit, the force S increases the resonance characteristic value Q of the PZT vibrator 4.

The tuning amplifier 7 amplifies the acoustic signal output from the vibration detection circuit 6 based on the tuning signal output from the PC 12. Specifically, the tuning amplifier 7 includes an amplifier circuit that amplifies a frequency band including the composite resonance frequency f!

t

Here, the composite resonance frequency f will be described.

t

Vibration detection element with a thickness of L [m] (eg PZT vibrator 4) Force S, fundamental resonance frequency of f [Hz]

R

Suppose you have a number. When a sample (for example, sample 3) with a thickness of AL [m] is attached to this vibration detection element (when attached), the overall resonance frequency between the vibration detection element and the sample is The frequency is slightly lower than the fundamental resonance frequency f of the output element, and the thickness is L + AL [m]

R

The composite resonance frequency f with the length of 1 as one wavelength. Thus, the composite resonance frequency f

t t The overall resonance frequency of the motion detection element and the sample. As will be described later, in this embodiment, PC12 t is used so that intermittent light is emitted from the diode array 1 at the composite resonance frequency f.

Controls each part.

A computer control noise generator (synthesizer) 13 generates a reference signal 10 having the same frequency as the composite resonance frequency f based on the control signal transmitted from the PC 12. This

t

This control signal indicates the composite resonance frequency f determined by the PC 12 as described later.

t signal.

The vector voltmeter 9 uses a reference signal 10 having the same frequency as the composite resonance frequency f.

t

The voltage level and phase of the acoustic signal output from the tuning amplifier 7 are measured. Specifically, the vector voltmeter 9 has a phase detection circuit for the sine component and a phase detection circuit for the cos component, and these phase detection circuits have the same frequency as the composite resonance frequency f.

t

Autocorrelation detection is performed using the reference signal 10. Thereby, the sin component and the cos component of the acoustic signal output from the tuning amplifier 7 can be separated. The vector voltmeter 9 transmits the sin component and the cos component of these acoustic signals to the VF converter 11. As described above, in this embodiment, the signal of the complex resonance frequency f is used as a reference signal, and the measured acoustic signal is correlated.

t

By detecting, the force S increases the sensitivity of the measured acoustic signal and the signal-to-noise ratio (SN ratio).

The VF converter 11 digitizes the sin component and the cos component of the acoustic signal transmitted from the vector voltmeter 9. The sin component and cos component of the digitized acoustic signal are captured by PC12.

[0017] The PC 12 includes a ROM and a hard disk that store programs and data, a CPU that executes the program, a RAM that functions as a work area when the CPU executes the program, and a temporary storage area for data. It has. The PC 12 also includes a user interface such as a keyboard and a mouse, and a display for displaying an image based on the processing result executed by the CPU.

[0018] The PC 12 generates the tuning signal 8 to the tuning amplifier 7 and the computer control noise generation. In addition to the control signal to the generator 13, a light intensity instruction signal and a diode selection instruction signal are generated.

Specifically, the PC 12 stores the light emission intensity in advance for each wavelength of the light emitted by each diode array power of the light emitting diode array 1. PC 12 shows an appropriate intensity according to the wavelength of light emitted from the light emitting diode array 1 (composite resonance frequency f) based on the sin component and the cos component of the digitized sound signal. Generate light intensity indication signal

t

To the diode power controller 14.

[0019] Further, the PC 12 emits intermittent light having a composite resonance frequency f among a plurality of diodes included in the diode array 1 based on the sin component and the cos component of the digitized acoustic signal.

t

A diode selection instruction signal for selecting a diode to be used for light generation is generated and transmitted to the specific diode switch 15.

The diode power controller 14 is a light intensity instruction signal output from the PC 12 and a signal transmitted from the converter control pulse generator 13 and has the same frequency as the composite resonance frequency f.

Based on the reference signal 10 having the t wave number, the intensity of light emitted from the diode array 1 is determined, and a light intensity signal indicating the determined light intensity is transmitted to the specific diode switch 15.

[0021] The specific diode switch 15 generates a complex resonance from the diodes included in the diode array 1 based on the light intensity signal transmitted from the diode power controller 14 and the diode selection instruction signal transmitted from the PC 12. For emitting intermittent light at frequency f

t

Outputs a noise signal (diode power noise) to the diode. As a result, intermittent light is emitted from the light emitting diode array 1 at the composite resonance frequency f [Hz].

t

Here, an example of a method for determining the composite resonance frequency f [Hz] will be described.

t

First, since the PZT vibrator 4 to which the sample 3 is attached is equivalent to an RLC series resonant circuit, it can be expressed as the following equations (1) to (3) as a steady-state solution.

[0022] [Equation 1] Is (t) = Aab si ncot + Be I coscot (1) V ROJ

Aab = ■ (2)

[(ωο ² — ω ² ) — R ² OJ ² ] ωο ² -ω ²

Bel = ■ (3)

^{^{ί (ωο 2 -ω 2) -}} 2 ω 2]

[0023] Here, I (t) is the stationary current [Α], ω is the angular frequency [rad / s], and ω is the resonant angular frequency [rad s 0

/ s]. R is the resistance [Ω] of the RLC series resonant circuit equivalent to the PZT vibrator 4 with sample 3 attached, and L is the RLC series resonant circuit equivalent to the と vibrator 4 with sample 3 attached. Reactance [Η].

The constant 示す shown in Equation (2) is the absorptive amplitude, and the constant B shown in Equation (3) is the elastic amplitude.

ab el

It is. Note that the value of the attenuation intensity in the PZT vibrator 4 to which the sample 3 is attached depends on the first term A sin cot on the right side of the equation (1).

ab

The constant B shown in equation (3) becomes 0 (zero) at the composite resonance frequency f. So this is actually

el t

In the embodiment, PC12 is the frequency at which the constant B (cos component) shown in Equation (3) becomes 0 (zero).

el

Is determined as the complex resonance frequency f [Hz]. And PC12 is the calculated complex resonance

t

Based on the frequency f, the control signal to be sent to the computer controlled noise generator 13 and the die t

A light intensity instruction signal to be transmitted to the odd power controller 14 and a diode selection instruction signal to be transmitted to the specific diode switch 15 are generated. As described above, in the present embodiment, intermittent light is emitted at the complex resonance frequency frequency f [Hz] that becomes the constant B force SO (zero) shown in Equation (3).

el t

I am trying to be lit.

Next, sound physical properties required by the PC 12 will be described. In the PC 12 provided in the optical microscope apparatus of the present embodiment, as the sound wave properties, the vibration attenuation coefficient α, the sound velocity V, the Young's modulus 率, the vibration attenuation coefficient τ, the concentration I of the specific substance in the sample 3, and From the surface of Sample 3 to the specified substance

0

Find depth D at.

[0025] (Vibration damping factor τ)

When a constant force F [N] is applied to the PZT vibrator 4 to which the sample 3 is attached, the voltage V [V] generated in the PZT vibrator 4 is given by the following equation (4). . V = kF (4)

[0026] Here, k is a mechanical electroacoustic conversion constant. This mechanical electroacoustic conversion constant is the total of the electromechanical conversion constants of sample 3 and PZT vibrator 4 (the composite electromechanical conversion constant of sample 3 and the mechanical electroacoustic conversion constant of PZT vibrator 4 are combined. Stuff). If the resistance of the RLC series resonant circuit equivalent to the PZT vibrator 4 with sample 3 attached is R [Ω], and the resonant current in the RLC series resonant circuit is Ι [Α], The voltage V [V] is given by the following equation (5).

V = RI (5)

From the equations (4) and (5), the following equation (6) is established.

R = kF / l (6)

In this way, the force F applied to the PZT vibrator 4 with the sample 3 attached is measured at a constant level, so the RLC series resonant circuit equivalent to the PZT vibrator 4 with the sample 3 attached is used. The resistance R is proportional to the reciprocal of the resonance current I in the RLC series resonance circuit. From the equation (6), the vibration damping rate τ is expressed by the following equation (7).

[0027] [Equation 2]

_R_ KF

(7)

[0028] Here, L is the reactance [H] of the RLC series resonance circuit equivalent to the PZT vibrator 4 to which the sample 3 is attached.

[0029] In this embodiment, the reactance L of the RLC series resonance circuit equivalent to the PZT vibrator 4 to which the sample 3 is attached and the force F applied to the PZT vibrator 4 to which the sample 3 is attached F And the electromechanical acoustic conversion constant k of the PZT vibrator 4 is constant. The PC 12 acquires the reactance L, the force F, and the mechanical electroacoustic conversion constant k based on the user's operation of the user interface provided in the PC 12, and stores them in a hard disk or the like in advance.

[0030] Then, the PC 12 obtains the amplitude (resonance current I) of the sin component when the cos component becomes 0 (zero) based on the sin component and the cos component of the acoustic signal, and calculates the obtained amplitude (resonance current). I) and the previously stored reactance L, force F, and mechanical electroacoustic conversion constant k are substituted into equation (7). The vibration damping rate τ (the overall vibration damping rate of sample 3 and ΡΖΤ vibrator 4) is obtained.

The vibration damping rate τ is the force that is the overall vibration damping rate of sample 3 and ΡΖΤ vibrator 4 (the combination of the vibration damping rate of sample 3 and the vibration damping rate of ΡΖΤ vibrator 4). Among them, the vibration attenuation rate of the vibrator 4 can be regarded as constant, and is sufficiently smaller than the vibration attenuation rate of the sample 3.

In the present embodiment, the sample 3 is irradiated with light having a short wavelength λ having a shallow depth of penetration into the sample 3 (hereinafter referred to as short wavelength light) from the diode array 1. Case

V

The vibration damping rate of sample 3 is obtained. Here, the short wavelength λ is, for example, in the sample 3

V V

A wavelength that does not reach a specific substance contained in Note that the vibration attenuation rate τ is the amplitude of the acoustic signal obtained from the vibrator 4 when the sample 3 is irradiated with short-wavelength light, and the measured amplitude of the acoustic signal is expressed as I in equation (11). Can be obtained by substituting

[0032] (Vibration damping coefficient α)

As described above, the PC 12 obtains the vibration damping coefficient α in the sample 3 attached to the heel vibrator 4 based on the vibration damping rate obtained using the equation (7). The vibration damping coefficient α is proportional to the inverse of the amplitude of the acoustic signal (resonance current I).

[0033] (Sonic velocity V, Young's modulus Ε)

PZ with sample 3 attached when sample 3 is irradiated with intermittent light at the complex resonance frequency f

t

In order to resonate the T oscillator 4, it is necessary to satisfy the following equation (8).

Τ = Τ + Δ Τ (8)

t R

Here, T is the time [s] that the speed of sound propagates through sample 3 and ΡΖΤ vibrator 4, and Τ is ΡΖ

t R

The time [s] that the sound velocity propagates through the T oscillator 4, and ΔΤ is the time [s] that the sound velocity propagates through the sample 3. Thus, T is the thickness A L of the sample 3 and the vibration detecting element (for example, PZT vibrator 4

t

) Is the period of the vibration mode in which the added value (= L + ΔL) with the thickness L is one wavelength.

Here, if the speed of sound in sample 3 is V, the following equation (9) holds. Therefore, the sound velocity V [m / s] is expressed by the following equation (10). The relationship between the Young's modulus E [Pa] of sample 3 and the speed of sound V is expressed by the following equation (11).

[0034] [Equation 3] ft fR ^V

P

Here, A L is the thickness [m] of the sample 3, and f is the resonance frequency [Hz] of the PZT vibrator 4

R

Yes, f is the composite resonant frequency [Hz], A f (= f — f) is the frequency shift [Hz], and t t R

β is the density [kg / m ³ ] of sample 3.

PC12 has the thickness AL of sample 3, the resonance frequency f of PZT vibrator 4, and the density p of sample 3.

R

Is acquired based on an operation by the user of the user interface provided in the PC 12, and stored in advance on a hard disk or the like.

PC12 calculates the composite resonance frequency f determined as described above and P t stored in advance.

The frequency shift A f is obtained from the resonance frequency f of the ZT vibrator 4. And PC12 asks

R

The frequency shift Δf stored in advance and the thickness ΔL of the sample 3 and the resonance frequency f of the PZT vibrator 4 are substituted into the equation (10), and the PZT vibrator 4 is Sound in sample 3 pasted

R

Find the speed V. After that, the PC 12 substitutes the calculated sound velocity V and the density p of the sample 3 stored in advance into the equation (11) to obtain the Young's modulus E of the sample 3.

In the present embodiment, when the sample 3 is irradiated with intermittent light at the composite resonance frequency f, PZT t

In addition to the sound velocity v generated in the sample 3 attached to the vibrator 4, the sound velocity V generated in the sample 3 attached to the PZT vibrator 4 when the sample 3 is irradiated with short wavelength light from the diode array 1, and The absorption light having the wavelength λ of the quantum mechanical absorption wavelength λ of the specific substance in Sample 3 was tested.

V s

When the sample 3 is irradiated, the sound velocity V generated in the sample 3 attached to the vibrator 4 is also obtained.

[0037] If the density ρ and the Young's modulus の of the sample 3 are expressed by a function of a place where the density ρ and the Young's modulus Ε are not constant, it is possible to know the density ρ and the Young's modulus の of the velocity V force sample 3. [0038] (Depth from surface of sample 3 to specific substance D)

PC12 is the composite resonance frequency f and fV produced by the sample 3 attached to the PZT vibrator 4 when short wavelength light is irradiated onto the sample 3 from the diode array 1 obtained as described above. Define Af (= ff). In addition, the quantum mechanical absorption wavelength of the specific substance in Sample 3

V tV R

s attached to PZT vibrator 4 when sample 3 is irradiated with absorbed light having a wavelength of λ

Af (= f f) is defined from the complex resonance frequencies f and f generated in sample 3. Pre-stored ts R s ts R

By substituting the thickness AL of the sample 3 into the following equation (12), the depth D [m] from the surface of the sample 3 to the specified substance is obtained.

D = AL {l- (Af / Δί)} --- (12)

s V

[0039] (Concentration I of specific substance in sample 3)

0

The concentration I of the specific substance at the depth D [m] from the surface of sample 3 is expressed by the following equation (13).

0

expressed.

[0040] [Number 4

I ₀ = I _s e ⁺ _t ^{S (} AL ^D ) ■ ■-(13)

[0041] Here, τ is the value in the sample 3 attached to the vibrator 4 when the sample 3 is irradiated with the absorbed light having the wavelength of the quantum mechanical absorption wavelength of the specific substance in the sample 3. Vibration attenuation factor, I is the intensity of the acoustic signal obtained by irradiating sample 3 with absorbed light and s

is there.

PC12 calculates the intensity I of the acoustic signal obtained by irradiating sample 3 with absorbed light.

. Then, PC12 substitutes the obtained intensity I of the acoustic signal I and the vibration damping rate τ obtained as described above into the equation (13), so that the position of the depth D [m] from the surface of the sample 3 is obtained. Obtain the concentration I of the specified substance in

0

[0042] (Create topograph)

When obtaining the acoustic properties as described above, the PC 12 performs the above-described measurements at a plurality of locations on the XY plane, for example, the sound velocity V, Young's modulus E, vibration damping factor τ, and a specific substance in the sample 3. Concentration I, depth D from the surface of sample 3 to the specified substance, and frequency transition Af

0

A topograph (3D image data) is generated and displayed on a display. PC12 is These topographic data are stored, for example, on a node disk.

[0043] In order to generate the topograph specifically, the PC 12 is arranged so that the position force of the sample 3 directly facing the photoacoustic resonance microscope 20 is a position (a plurality of predetermined positions) set in advance on a hard disk or the like. The drive unit 19 (X direction sample stage drive unit 19a and Y direction sample stage drive unit 19b) is sequentially driven. Then, the PC 12 performs the above-described measurement at a plurality of positions, and at these positions, the sound velocity V, Young's modulus E, vibration damping ratio τ, specific substance concentration I in the sample 3, and the surface of the sample 3 To the depth D and the frequency transition A f from

0

Based on the obtained result, a topograph (3D image data) is generated. The display provided on the PC 12 displays the generated topograph.

[0044] It should be noted that the PC 12 obtains the frequency shift A f suitable for obtaining the sound velocity V and the Young's modulus E from the topography of the frequency transition A f based on the user's operation of the user interface provided in the PC 12. Then, using the obtained frequency shift A f, the force S can be obtained to obtain the sound velocity V and Young's skewer E of sample 3.

FIG. 3 is a diagram showing an example of a topograph of the frequency shift A f in the sample 3 shown in FIG. FIG. 4 is a diagram showing an example of a topograph of the vibration damping rate τ in the sample 3 shown in FIG. In Fig. 3 and Fig. 4, 40 points are obtained per 2 [mm], and a position resolution of ± 50 [111] is obtained.

[0046] Sample 3 was formed by cutting an aluminum plate (aluminum adhesive tape) with scissors into a substantially equilateral triangle. In the topographs 300 and 400 shown in FIG. 3 and FIG. 4, this shows that one side of sample 3 (the side on the right side) is turned up! /. In the center of sample 3, it can be seen that sample 3 with low frequency deviation Af is well bonded to PZT transducer 4. That is, in the central part of the sample 3 where the sample 3 is well bonded to the PZT vibrator 4, the time required for the acoustic signal to propagate through the sample 3 is shortened, so the frequency shift Af is reduced.

[0047] In the present embodiment, the PC 12 uses a frequency shift Δf having a relatively gentle change in the center of the sample 3 and a low value of the frequency shift Af in the topograph 300 of the frequency shift Af. Obtain the sound velocity V and Young's modulus E of sample 3 based on the interface operation. [0048] As described above, in the present embodiment, the PZT vibration is obtained by irradiating the surface (upper surface) of the sample 3 to be measured fixed (adhered) to the surface (upper surface) of the PZT vibrator 4 with intermittent light. Based on the amplitude of the acoustic signal generated from the child 4, the composite resonance frequency f is obtained, and the obtained composite resonance t

Diode array t so that intermittent light of frequency f is emitted from diode array 1.

1 The light emission state of 1 was controlled. Then, using the obtained composite resonance frequency f, the test t

The acoustic wave properties such as sound velocity V and Young's modulus E of material 3 were calculated. Accordingly, various sound wave physical properties can be obtained only by the vibration attenuation rate, and more detailed information of the sample 3 can be obtained than before by using the photoacoustic effect. Therefore, for example, it is possible to perform a biopsy or the like with high accuracy.

[0049] Further, since the vibration damping rate α, the vibration damping rate τ, and the depth D from the surface of the sample 3 to the specific substance are also obtained, more detailed information on the sample 3 can be obtained.

Furthermore, sound velocity V, Young's modulus Ε, vibration damping rate τ, concentration of specific substance in sample 3, I, sample 3

Since the topography (three-dimensional image data) of the depth D from the surface of 0 to the specific substance and the frequency transition Δ f is generated and displayed on the display, the state of the sample 3 can be visually recognized by the user. Can be easily recognized. Therefore, for example, cancer cells that proliferated abnormally and normal cells around them in a biopsy sample or the like can be easily distinguished visually by a topograph (for example, a topography with a Young's modulus E (considering the density) sound velocity V). It becomes possible.

[0050] Further, since the frequency deviation A f used to determine the sound velocity V and the Young's modulus E is determined based on the topograph 300, the sound velocity V and the Young's modulus E can be determined more accurately. .

[0051] In this embodiment, the force that is used to process the acoustic signal into a form that can be processed by the PC 12 using the VF converter 11, and can be processed by the PC 12 using an AD converter instead of the VF converter 11. The acoustic signal may be processed into a shape.

In the present embodiment, the sound velocity V and the Young's modulus E of the sample 3 are obtained using the frequency shift Af obtained based on the operation by the user referring to the topograph 300 of the frequency shift Af. However, this is not always necessary. That is, the frequency used to determine the sound velocity V and Young's modulus E of sample 3 from the topography 300 of the frequency shift A f The numerical deviation Δf may be determined, and the sound velocity V and Young's modulus E of the sample 3 may be obtained using the determined frequency deviation Δf. In determining the frequency deviation A f, for example, the minimum value of the frequency deviation Δ f in the topography 300 of the frequency deviation Δ f may be used! /, And the frequency deviation in the topography 300 of the frequency deviation Δ f may be used. The average value of the shift Δf may be used! /, And the minimum value or the average value in the region where the change of the frequency shift Δf in the topograph 300 of the frequency shift Δf is below the threshold may be used! / ,.

In this embodiment, intermittent light is emitted using a light emitting diode, but it is not always necessary to use a light emitting diode. For example, a laser diode may be used. Further, there may be a plurality of light sources such as light emitting diodes and laser diodes. Further, the force beam diameter exemplified in the case where the beam diameter is 50 [〃m] is not limited to this, and can be set as follows, for example. If the beam diameter is reduced, the position resolution can be improved.

In the present embodiment, the X-direction sample stage driving device 19a and the Y-direction sample stage driving device 19b are driven to drive the XY operation sample stage 5 in two directions, the X-axis direction and the Y-axis direction. The XY working sample stage 5 may be driven only in one direction in the axial direction and the Y-axis direction.

In the present embodiment, the case where the PZT vibrator 4 is used as the vibration detection element has been described as an example. However, the vibration detection element is not limited to the PZT vibrator (piezoelectric element), and the sample Any element may be used as long as it is an element that detects the vibration 3. For example, a magnetostrictive resonance vibrator, a PDF synthetic resonance oscillator, an electrostatic induction synthetic resonance oscillator, an electromagnetic induction type synthetic resonance oscillator, or a light detection synthetic resonance oscillator can be used as the vibration detection element.

The embodiment of the present invention described above can be realized by a computer executing a program. Further, a means for supplying the program to the computer, for example, a computer-readable recording medium such as a CD-ROM on which the program is recorded, or a transmission medium for transmitting the program is also described. Can be applied as power S. In addition, a program product such as a computer-readable recording medium in which the above program is recorded can also be applied as an embodiment of the present invention. The above program, computer-readable recording medium, transmission medium, and program Products are included within the scope of the present invention.

[0056] In addition, the above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. It is. In other words, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

Industrial applicability

[0057] According to the present invention, an overall composite resonance frequency of the vibration detection element attached to the sample and detecting the vibration of the sample and the sample attached to the vibration detection element is determined by the vibration detection element. Since it is determined based on the detected acoustic signal indicating the vibration of the sample, it is possible to determine more sound wave properties than before by using the composite resonance frequency.

Claims

The scope of the claims

[1] a vibration detecting element attached to the sample and detecting the vibration of the sample;

A photoacoustic microscope for irradiating intermittent excitation light on a sample to which the vibration detection element is attached;

Based on an acoustic signal indicating the vibration of the sample detected by the vibration detection element, the light emitting means for providing the intermittent excitation light to the photoacoustic microscope! /, And the sample and the vibration detection element The frequency derivation means for obtaining the overall composite resonance frequency of the sample and the composite resonance frequency obtained by the frequency derivation means so that the intermittent excitation light is irradiated to the sample attached to the vibration detection element, And a control means for controlling the light emitting means.

[2] The method includes a sound wave property deriving unit that obtains at least one of a sound velocity in the sample and a Young's modulus of the sample using the complex resonance frequency obtained by the frequency deriving unit. The photoacoustic measurement system according to claim 1.

[3] Correlation detection means for performing correlation detection of an acoustic signal indicating the vibration of the sample detected by the vibration detection element using a signal having the frequency of the complex resonance frequency as a reference signal;

The range of claim 2, wherein the frequency deriving means obtains an overall composite resonance frequency of the sample and the vibration detecting element based on the acoustic signal correlated detected by the correlation detecting means. The photoacoustic measurement system described in 1.

[4] First sound speed derivation for obtaining sound speed in the sample when the intermittent excitation light having a quantum mechanical absorption wavelength of the substance contained in the sample is irradiated on the sample attached to the vibration detecting element Means,

Second sound speed deriving means for obtaining sound speed in the sample when the intermittent excitation light having a wavelength that does not reach the substance contained in the sample is irradiated to the sample attached to the vibration detecting element;

Based on the sound speed obtained by the first sound speed deriving means and the second sound speed deriving means, and the thickness of the sample, the depth from the surface of the sample to the substance is obtained. 4. The photoacoustic measurement system according to claim 3, further comprising second sound wave property derivation means.

[5] The light emitting means is arranged so that the intermittent excitation light is irradiated to the sample attached to the vibration detecting element at a frequency based on a quantum mechanical absorption wavelength of a substance contained in the sample. A second control means for controlling;

The vibration of the sample detected by the vibration detection element is obtained by irradiating the intermittent excitation light to the sample attached to the vibration detection element from the light emitting means controlled by the second control means. 5. The photoacoustic measurement system according to claim 4, further comprising: a third sound wave property deriving unit that obtains a vibration attenuation rate in the sample using an acoustic signal shown.

[6] The sample detected by the vibration detection element by irradiating the intermittent excitation light to the sample attached to the vibration detection element from the light emitting means controlled by the second control means The fourth acoustic property derivation for obtaining the concentration of the substance contained in the sample using the acoustic signal indicating the vibration of the sample and the vibration attenuation factor obtained by the third acoustic property derivation means using the acoustic signal. The photoacoustic measurement system according to claim 5, further comprising: means.

[7] A position changing unit that changes a relative position between the sample and the photoacoustic microscope is provided. The sound wave property derivation unit is configured to change the sound wave property at each position changed by the position change unit. The photoacoustic measurement system according to claim 6, wherein the photoacoustic measurement system is obtained.

[8] The light according to claim 7, further comprising display means for displaying a three-dimensional image on a display device based on the sound wave physical properties obtained at the respective positions changed by the position changing means. Acoustic measurement system.