JP5248443B2 - Ultrasonic microscope - Google Patents
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- JP5248443B2 JP5248443B2 JP2009184735A JP2009184735A JP5248443B2 JP 5248443 B2 JP5248443 B2 JP 5248443B2 JP 2009184735 A JP2009184735 A JP 2009184735A JP 2009184735 A JP2009184735 A JP 2009184735A JP 5248443 B2 JP5248443 B2 JP 5248443B2
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Description
本発明は，被検体に超音波を照射し，前記被検体からの反射超音波を検出することによって前記被検体の内部の観測信号を得る超音波顕微鏡に関するものである。 The present invention relates to an ultrasonic microscope that obtains an observation signal inside the subject by irradiating the subject with ultrasonic waves and detecting reflected ultrasonic waves from the subject.
従来より，被検体に超音波を照射し，前記被検体からの反射超音波を検出することによって被検体の内部状態の観測信号を得る超音波顕微鏡が知られている。超音波顕微鏡は，光や電子線では得られない被検体内部の情報が得られることから，被検体の弾性等の力学的性質の評価の他，内部欠陥の検出等にも多用されている。
従来の超音波顕微鏡は，特許文献１に示されるように，高周波の電気信号が印加される圧電膜，及びその圧電膜（圧電素子）が表面に設けられた音響レンズとを備えている。前記圧電幕から放射された超音波は，前記音響レンズを通じて被検体の微小部位に照射され，その被検体に反射した超音波が再び音響レンズを通じて圧電膜に到達する。そして，圧電膜により，反射超音波が電気信号に変換され，その電気信号に基づいて被検体の内部状態が画像化される。
2. Description of the Related Art Conventionally, there has been known an ultrasonic microscope that obtains an observation signal of an internal state of a subject by irradiating the subject with ultrasonic waves and detecting reflected ultrasonic waves from the subject. The ultrasonic microscope can obtain information inside the subject that cannot be obtained by light or electron beam. Therefore, the ultrasonic microscope is frequently used not only for evaluating mechanical properties such as elasticity of the subject but also for detecting internal defects.
As shown in Patent Document 1, a conventional ultrasonic microscope includes a piezoelectric film to which a high-frequency electric signal is applied, and an acoustic lens on which the piezoelectric film (piezoelectric element) is provided. The ultrasonic wave radiated from the piezoelectric curtain is irradiated to the minute part of the subject through the acoustic lens, and the ultrasonic wave reflected by the subject reaches the piezoelectric film again through the acoustic lens. The reflected ultrasonic waves are converted into electrical signals by the piezoelectric film, and the internal state of the subject is imaged based on the electrical signals.
ところで，超音波顕微鏡では，超音波の回析の影響から超音波の波長が短いほど，即ち，超音波の周波数が高いほど空間分解能が高くなる。
また，例えば，被検体が，表面に数μｍ〜サブミクロンの厚みの配線膜や絶縁膜が形成された半導体デバイス等であるような場合，超音波顕微鏡によってその被検体における膜の界面の接合評価（膜の剥離の有無評価等）のための観測を行うためには，膜厚（数μｍ）以下のオーダーの空間分解能が要求される。また，電子部品が実装された基板における電極部の大きさは数十μｍ程度であるが，その電極部内の欠陥評価（ボイドの有無評価等）を行う場合も，超音波顕微鏡には数μｍ以下の空間分解能が要求される。
しかしながら，圧電膜により超音波の放射及び受波が行われる従来の超音波顕微鏡では，圧電膜の容量成分や共振特性に起因し，発生させることができる実用的な超音波の周波数は数百ＭＨｚ程度以下（波長は１０μｍ以上）にすぎない。そのため，従来の超音波顕微鏡の空間分解能は，超音波の回析限界により１０μｍ程度以上（波長と同程度）にすぎず，数μｍ以下のオーダーの高い空間分解能を実現できないという問題点があった。
従って，本発明は上記事情に鑑みてなされたものであり，その目的とするところは，数μｍ以下のオーダーの高い空間分解能で被検体の内部を観測できる超音波顕微鏡を提供することにある。
By the way, in the ultrasonic microscope, the spatial resolution becomes higher as the wavelength of the ultrasonic wave is shorter, that is, as the frequency of the ultrasonic wave is higher, due to the influence of ultrasonic diffraction.
For example, when the specimen is a semiconductor device having a wiring film or an insulating film with a thickness of several μm to submicron formed on the surface, the bonding evaluation of the film interface in the specimen is performed using an ultrasonic microscope. In order to perform observation for (evaluation of presence / absence of film peeling), a spatial resolution of the order of film thickness (several μm) or less is required. In addition, the size of the electrode portion on the substrate on which the electronic component is mounted is about several tens of μm. However, when evaluating defects in the electrode portion (evaluation of presence / absence of voids, etc.), the ultrasonic microscope has several μm or less. Spatial resolution is required.
However, in a conventional ultrasonic microscope in which ultrasonic waves are radiated and received by a piezoelectric film, the practical ultrasonic frequency that can be generated is several hundred MHz due to the capacitive component and resonance characteristics of the piezoelectric film. It is less than about (wavelength is 10 μm or more). Therefore, the spatial resolution of the conventional acoustic microscope is only about 10 μm or more (same as the wavelength) due to the diffraction limit of ultrasonic waves, and there is a problem that high spatial resolution on the order of several μm or less cannot be realized. .
Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide an ultrasonic microscope capable of observing the inside of a subject with a high spatial resolution on the order of several μm or less.
上記目的を達成するために本発明は、被検体に超音波を照射し、前記被検体からの反射超音波を検出することによって前記被検体の内部の観測信号を得る超音波顕微鏡であり、次の（１）〜（９）に示される各構成要素を備えている。
（１）励起用パルス光が照射されることにより、熱弾性効果によって超音波を発する超音波発生部。
（２）前記励起用パルス光を前記超音波発生部に照射する励起用パルス光照射手段。
（３）前記超音波発生部で発生した超音波が前記被検体に照射されて反射した前記反射超音波を受波することにより、光弾性効果によって光反射率が変化する超音波受波部。なお、光弾性効果による光反射率の変化は、光弾性効果による屈折率の変化と換言してもよい。
（４）前記超音波受波部に測定光を照射する測定光照射手段。
（５）前記超音波受波部に照射された前記測定光の反射光を検出する測定光検出手段。
（６）表面に前記超音波受波部が形成され、該超音波発生部で発生した超音波を前記被検体の一部に集束させる音響レンズ。
（７）前記音響レンズにおける、前記超音波受波部を兼ねる前記超音波発生部が形成された面を含む当該音響レンズの表層部に、前記測定光を前記超音波発生部との界面に沿ってその界面に対して多重反射させつつ伝播させる導光路が形成されている。
（８）前記測定光照射手段が、前記導光路に前記測定光を入射させる。
（９）前記測定光検出手段が、前記導光路を伝播した前記測定光を検出する。
例えば、前記音響レンズの表面に、前記超音波発生部に加え、前記超音波受波部も形成されていることが考えられる。
前記音響レンズの作用により、超音波の集束位置における応力を高めることができ、前記被検体の内部状態を高感度で（高いＳＮ比で）検出できる。
また、前記超音波発生部及び前記超音波受波部の具体例としては、前記音響レンズの表面に形成された金属（モリブデン，金，銅，アルミニウム等）の膜のように、熱膨張係数が比較的大きく熱容量の小さなものが考えられる。
また、前記超音波発生部が前記超音波受波部を兼ねるものであることも考えられる。
また、前記超音波受波部を兼ねる前記超音波発生部の光弾性効果による光反射率の変化、即ち、前記超音波受波部における反射超音波の受波状況を、非常に高感度で（高いＳＮ比で）検出できる。
In order to achieve the above object, the present invention is an ultrasonic microscope that obtains an observation signal inside the subject by irradiating the subject with ultrasonic waves and detecting reflected ultrasonic waves from the subject. The components shown in (1) to (9) are provided.
(1) An ultrasonic generator that emits ultrasonic waves by a thermoelastic effect when irradiated with excitation pulsed light.
(2) Excitation pulse light irradiation means for irradiating the ultrasonic pulse generator with the excitation pulse light.
(3) An ultrasonic wave receiving unit in which light reflectance is changed by a photoelastic effect by receiving the reflected ultrasonic wave that is reflected when the ultrasonic wave generated by the ultrasonic wave generating unit is applied to the subject. Note that the change in the light reflectance due to the photoelastic effect may be restated as the change in the refractive index due to the photoelastic effect.
(4) Measuring light irradiation means for irradiating the ultrasonic wave receiving part with measuring light.
(5) Measurement light detection means for detecting reflected light of the measurement light irradiated on the ultrasonic wave receiving section.
(6) An acoustic lens in which the ultrasonic wave receiving part is formed on the surface and the ultrasonic wave generated by the ultrasonic wave generating part is focused on a part of the subject.
(7) In the acoustic lens, the measurement light is applied to the surface layer portion of the acoustic lens including the surface on which the ultrasonic wave generation unit also serving as the ultrasonic wave reception unit is formed along the interface with the ultrasonic wave generation unit. A light guide path is formed that propagates while being multiple-reflected with respect to the interface.
(8) The measurement light irradiation unit causes the measurement light to enter the light guide.
(9) The measurement light detection unit detects the measurement light propagated through the light guide.
For example, the surface of the front Symbol acoustic lens, wherein in addition to the ultrasound generating unit, the ultrasonic wave reception unit is also considered to have been formed.
By the action of the acoustic lens, the stress at the ultrasonic focusing position can be increased, and the internal state of the subject can be detected with high sensitivity (with a high S / N ratio).
In addition, as a specific example of the ultrasonic wave generation unit and the ultrasonic wave reception unit, the coefficient of thermal expansion is, for example, a metal (molybdenum, gold, copper, aluminum, etc.) film formed on the surface of the acoustic lens. A relatively large heat capacity can be considered.
Moreover, it is also conceivable that the ultrasonic wave generation unit also serves as the ultrasonic wave reception unit.
In addition, the change in the light reflectance due to the photoelastic effect of the ultrasonic wave generation unit that also serves as the ultrasonic wave reception unit, that is, the reception state of the reflected ultrasonic wave in the ultrasonic wave reception unit is very sensitive ( Can be detected (with a high signal-to-noise ratio).
ところで，前記超音波発生部は，前記励起用パルス光の照射による熱膨張によって超音波（熱弾性波）を発する。ここで，前記超音波発生部における前記励起用パルス光の入射面が自由表面である場合，主としてその自由表面で熱膨張変位が生じ，そこで生じた超音波はその自由表面から放散されやすい。そのことは，前記超音波発生部における前記励起用パルス光の入射面からその反対側の面へ向かう超音波，即ち，前記被検体に向かう超音波の発生効率の低下につながる。
そこで，本発明に係る超音波顕微鏡が，以下に示す固体接合部材を備えれば好適である。前記固定接合部材は，前記超音波発生部における前記励起用パルス光の入射面に接合され，前記励起用パルス光を透過させる固体からなる部材である。前記固体接合部材は，前記超音波発生部における前記励起用パルス光の入射面における熱膨張変位を拘束するためのものである。また，前記超音波発生部における前記固体接合部材が接合される面は，前記被検体に向かう側と反対側の面である。
前記固体接合部材の作用により，前記超音波発生部から前記被検体に向かう超音波の発生効率を高めることができる。
また，前記固体接合部材は，前記超音波発生部よりもヤング率の大きい部材であることが望ましい。これにより，前記超音波発生部における前記励起用パルス光の入射面の変位の拘束力がより高くなり，前記被検体に向かう超音波の発生効率をより高めることができる。
By the way, the ultrasonic wave generator emits an ultrasonic wave (thermoelastic wave) by thermal expansion due to irradiation of the excitation pulse light. Here, when the incident surface of the excitation pulse light in the ultrasonic wave generation unit is a free surface, thermal expansion displacement occurs mainly on the free surface, and the generated ultrasonic wave is easily diffused from the free surface. This leads to a decrease in generation efficiency of ultrasonic waves from the excitation pulse light incident surface to the opposite surface of the ultrasonic wave generation unit, that is, ultrasonic waves toward the subject.
Therefore, it is preferable that the ultrasonic microscope according to the present invention includes the solid bonding member described below. The fixed joining member is a member made of a solid that is joined to an entrance surface of the excitation pulse light in the ultrasonic wave generation unit and transmits the excitation pulse light. The solid bonding member is for restraining thermal expansion displacement on the incident surface of the excitation pulse light in the ultrasonic wave generation unit. Further, the surface to which the solid bonding member is bonded in the ultrasonic wave generation unit is a surface opposite to the side facing the subject.
Due to the action of the solid joining member, it is possible to increase the generation efficiency of ultrasonic waves from the ultrasonic wave generation unit toward the subject.
The solid joining member is preferably a member having a Young's modulus larger than that of the ultrasonic wave generating portion. Thereby, the restraint force of the displacement of the incident surface of the excitation pulsed light in the ultrasonic wave generation unit becomes higher, and the generation efficiency of ultrasonic waves toward the subject can be further increased.
パルス光が照射された物質は，熱弾性効果により，そのパルス光とパルス幅が同じ熱弾性波を発生させる。本発明に係る超音波顕微鏡は，前記超音波発生部の熱弾性効果によって弾性波（超音波）を発生させる。従って，本発明に係る超音波顕微鏡は，前記励起用パルス光照射手段によって，例えばパルス幅（時間幅）が１ナノ秒以下の前記励起用パルス光を前記超音波発生部に照射すると，ＧＨｚオーダーの周波数（波長が数μｍ以下）の超音波を発生させることができる。
また，前記測定光検出手段によって検出される前記測定光の反射光の強度は，前記超音波受波部における反射超音波の受波状況が高感度で反映される。
従って，本発明に係る超音波顕微鏡により，数μｍ以下のオーダー（例えば，サブμｍオーダー）の高い空間分解能で被検体の内部を高感度で観測できる。
The material irradiated with the pulsed light generates a thermoelastic wave having the same pulse width as the pulsed light due to the thermoelastic effect. The ultrasonic microscope according to the present invention generates an elastic wave (ultrasonic wave) by the thermoelastic effect of the ultrasonic wave generator. Therefore, in the ultrasonic microscope according to the present invention, when the excitation pulse light having a pulse width (time width) of, for example, 1 nanosecond or less is irradiated to the ultrasonic wave generation unit by the excitation pulse light irradiation means, the order of GHz is obtained. Can be generated (with a wavelength of several μm or less).
In addition, the intensity of the reflected light of the measurement light detected by the measurement light detection unit reflects the reception status of the reflected ultrasonic wave in the ultrasonic wave receiving unit with high sensitivity.
Therefore, with the ultrasonic microscope according to the present invention, the inside of the subject can be observed with high sensitivity at a high spatial resolution of the order of several μm or less (for example, sub-μm order).
また，本発明に係る超音波顕微鏡が，次の（１０）及び（１１）に示される構成を有することも考えられる。
（１０）前記測定光照射手段が，少なくとも前記励起用パルス光が前記被検体に照射されてから所定期間内において前記測定光を連続照射するものである。
（１１）前記測定光検出手段が，前記超音波受波部に照射された前記測定光の反射光の強度の時系列変化を検出するものである。
これにより，従来の超音波顕微鏡と同様に，超音波が出力された時点から前記測定光の反射光のピーク強度が検出されるまでの時間により，前記被検体の内部に存在する欠陥や不純物等の深さを特定できる。但し，時間分解能の高い前記測定光検出手段を採用する必要がある。
一方，本発明に係る超音波顕微鏡が，次の（１２）〜（１４）に示される構成を有することも考えられる。
（１２）前記励起用パルス光照射手段が，前記励起用パルス光を連続照射するものである。
（１３）前記測定光照射手段が，前記励起用パルス光の照射タイミングと同期してパルス状の前記測定光を出力するパルス測定光出力手段と，そのパルス測定光出力手段から前記被検体までの前記測定光の光路長を変更する光路長変更手段とを備えている。
（１４）前記測定光検出手段が，前記光路長変更手段による前記測定光の光路長の変更に応じて前記超音波受波部に照射された前記測定光の反射光の強度の検出信号をサンプリングするものである。
前記測定光の光路長の変更により，前記被検体における前記励起用パルス光の照射タイミングに対する前記測定光の照射タイミングが変化する。そのため，前記測定光検出手段の検出結果は，反射超音波が前記超音波受波部へ到達するタイミングを走査した信号となる。また，光速が速いことから，前記測定光の光路長の変更の分解能が特に高くなくても，十分に高い分解能での前記走査が可能となる。これにより，特に時間分解能の高い前記測定光検出手段を採用しなくても，前記被検体の内部に存在する欠陥や不純物等の深さを高い分解能で特定できる。
It is also conceivable that the ultrasonic microscope according to the present invention has a configuration shown in the following (10) and (11).
(10) The measurement light irradiation means continuously irradiates the measurement light within a predetermined period after at least the excitation pulse light is irradiated on the subject.
(11) The measurement light detection means detects a time-series change in the intensity of the reflected light of the measurement light applied to the ultrasonic wave receiving unit.
Thus, as in the case of the conventional ultrasonic microscope, defects, impurities, etc. existing inside the subject are determined depending on the time from when the ultrasonic wave is output until the peak intensity of the reflected light of the measurement light is detected. The depth of can be specified. However, it is necessary to employ the measurement light detection means having a high time resolution.
On the other hand, it is also conceivable that the ultrasonic microscope according to the present invention has a configuration shown in the following (12) to (14).
(12) The excitation pulsed light irradiation means continuously emits the excitation pulsed light.
(13) The measurement light irradiation means outputs pulse measurement light output means for outputting the pulsed measurement light in synchronization with the irradiation timing of the excitation pulse light, and from the pulse measurement light output means to the subject. Optical path length changing means for changing the optical path length of the measurement light.
(14) The measurement light detection unit samples a detection signal of the intensity of the reflected light of the measurement light irradiated on the ultrasonic wave receiving unit according to the change of the optical path length of the measurement light by the optical path length change unit To do.
By changing the optical path length of the measurement light, the irradiation timing of the measurement light with respect to the irradiation timing of the excitation pulse light in the subject changes. For this reason, the detection result of the measurement light detection means is a signal obtained by scanning the timing at which the reflected ultrasonic wave reaches the ultrasonic wave receiving unit. Further, since the speed of light is high, the scanning with sufficiently high resolution is possible even if the resolution of changing the optical path length of the measurement light is not particularly high. Thereby, the depth of defects, impurities, etc. existing inside the object can be specified with high resolution without employing the measurement light detection means with particularly high time resolution.
本発明によれば，超音波顕微鏡において，被検体に対して高周波数の超音波を照射でき，数μｍ以下のオーダーの高い空間分解能で被検体の内部を観測できる。 According to the present invention, an ultrasonic microscope can irradiate a subject with high-frequency ultrasonic waves, and the inside of the subject can be observed with a high spatial resolution on the order of several μm or less.
以下添付図面を参照しながら，本発明の実施の形態について説明し，本発明の理解に供する。尚，以下の実施の形態は，本発明を具体化した一例であって，本発明の技術的範囲を限定する性格のものではない。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
まず，図１を参照しつつ，本発明の第１実施形態に係る超音波顕微鏡Ｘ１について説明する。
超音波顕微鏡Ｘ１は，被検体１に超音波を照射し，その被検体１からの反射超音波（エコー）を検出することによって前記被検体１の内部状態の観測信号を得る。その観測信号に基づいて，前記被検体１の内部欠陥や不純物等の位置（深さ）が特定される。
図１に示されるように，超音波顕微鏡Ｘ１は，励起用パルス光照射部１０と，測定光照射部２０と，超音波送受部Ｚ１と，測定光検出部４０と，Ｘ−Ｙステージ５１と，ステージ制御部５２と，計算機６０と，同期回路６１とを備えている。
First, the ultrasonic microscope X1 according to the first embodiment of the present invention will be described with reference to FIG.
The ultrasonic microscope X 1 obtains an observation signal of the internal state of the subject 1 by irradiating the subject 1 with ultrasonic waves and detecting reflected ultrasonic waves (echoes) from the subject 1. Based on the observation signal, the position (depth) of the internal defect or impurity of the subject 1 is specified.
As shown in FIG. 1, the ultrasonic microscope X1 includes an excitation pulse light irradiation unit 10, a measurement light irradiation unit 20, an ultrasonic transmission / reception unit Z1, a measurement light detection unit 40, an XY stage 51, and the like. , A stage control unit 52, a computer 60, and a synchronization circuit 61.
前記超音波送受部Ｚ１は，音響レンズ３１の表面に膜部材３２が形成（成膜）された部材である。前記音響レンズ３１は，その内部を超音波が少ない減衰で伝播されるよう石英ガラスやサファイア等の硬質材料からなる部材である。
前記励起用パルス光照射部１０は，前記励起用パルス光Ｂ１を発生させて前記膜部材３２の１点に照射するものであり，励起用パルス光照射手段の一例である。
前記励起用パルス光照射部１０は，励起用パルス光を出力するパルスレーザ光源１１と，ミラー１２及びレンズ１３を備えている。
前記パルスレーザ光源１１は，例えば，波長５３２ｎｍ程度，パルス幅１００ｐｓ（ピコ秒）程度のパルス状のレーザ光である励起用パルス光Ｂ１を出力する光源（ＹＡＧレーザ等）である。
前記パルスレーザ光源１１から出射された前記励起用パルス光Ｂ１は，前記ミラー１２により前記膜部材３２の方向へ変向され，前記レンズ１３によってそのビーム径が調節されて前記膜部材３２に照射される。
前記同期回路６１は，前記パルスレーザ光源１１及び後述する高速オシロスコープ４３に対してパルス光出力開始信号を供給する回路である。前記パルスレーザ光源１１は，前記パルス光出力開始信号が供給されるごとにパルス光（前記励起用パルス光Ｂ１）を出射する。
The ultrasonic transmission / reception unit Z <b> 1 is a member in which a film member 32 is formed (film formation) on the surface of the acoustic lens 31. The acoustic lens 31 is a member made of a hard material such as quartz glass or sapphire so that the ultrasonic wave is propagated in the inside with a small attenuation.
The excitation pulsed light irradiation unit 10 generates the excitation pulsed light B1 and irradiates it on one point of the film member 32, and is an example of excitation pulsed light irradiation means.
The excitation pulsed light irradiation unit 10 includes a pulse laser light source 11 that outputs excitation pulsed light, a mirror 12, and a lens 13.
The pulse laser light source 11 is a light source (such as a YAG laser) that outputs excitation pulsed light B1, which is pulsed laser light having a wavelength of about 532 nm and a pulse width of about 100 ps (picoseconds).
The excitation pulsed light B1 emitted from the pulsed laser light source 11 is redirected by the mirror 12 toward the film member 32, and its beam diameter is adjusted by the lens 13 and irradiated to the film member 32. The
The synchronization circuit 61 is a circuit that supplies a pulsed light output start signal to the pulsed laser light source 11 and a high-speed oscilloscope 43 described later. The pulse laser light source 11 emits pulse light (the excitation pulse light B1) every time the pulse light output start signal is supplied.
前記膜部材３２は，例えば，モリブデン，金，銅，アルミニウム等の金属の膜である。
前記膜部材３２は，前記励起用パルス光Ｂ１が照射されると，熱弾性効果により，そのパルス光Ｂ１とパルス幅が同じ熱弾性波を発生させる。即ち，前記膜部材３２は，励起用パルス光Ｂ１が照射されることにより，熱弾性効果によって超音波を発する超音波発生部の一例である。
従って，前記励起用パルス光照射部１０によってパルス幅（時間幅）が１００ｐｓ以下の前記励起用パルス光Ｂ１が前記膜部材３２に照射されると，１０ＧＨｚ以上の周波数（波長が１μｍ以下）の超音波を発生させることができる。
Ｑスイッチ動作やモードロック等によって動作するレーザ光源により，数ｎｓ以下のパルス幅のパルス光を出力することは通常行われることである。そのため，前記励起用パルス光照射部１０は一般的な機器により実現できる。
The film member 32 is, for example, a metal film such as molybdenum, gold, copper, or aluminum.
When the excitation pulsed light B1 is irradiated, the film member 32 generates a thermoelastic wave having the same pulse width as that of the pulsed light B1 due to the thermoelastic effect. That is, the film member 32 is an example of an ultrasonic wave generator that emits ultrasonic waves by the thermoelastic effect when irradiated with the excitation pulsed light B1.
Accordingly, when the excitation pulsed light B1 having a pulse width (time width) of 100 ps or less is irradiated on the film member 32 by the excitation pulsed light irradiation unit 10, the frequency (wavelength is 1 μm or less) of 10 GHz or more is exceeded. Sound waves can be generated.
It is a common practice to output pulsed light with a pulse width of several ns or less by a laser light source that operates by Q-switch operation or mode lock. Therefore, the excitation pulsed light irradiation unit 10 can be realized by a general device.
また，前記音響レンズ３１は，前記膜部材３２で発生した超音波を伝播させて前記被検体１の微小な観測部位１ａに集束させるものである。
具体的には，前記音響レンズ３１は，直方体の部材における一つの面に湾曲面を形成する窪み３３が設けられた部材である。前記窪み３３は，前記音響レンズ３１における前記膜部材３２が形成された面に対し反対側の面に形成されている。
前記膜部材３２における励起用パルス光の照射点で発生した超音波は，前記音響レンズ３１の内部を伝播して前記窪み３３に到達し，その窪み３３の表面から被検体１の観測部位１ａに向かう方向に放射される。
前記音響レンズ３１における前記窪み３３と被検体１との間には，水などのカップリング材２が充填されている。
また，前記音響レンズ３１は，前記観測部位１ａで反射した超音波（反射超音波）を前記膜部材３２における測定光の照射点に集束させるものでもある。
The acoustic lens 31 propagates the ultrasonic wave generated by the film member 32 and focuses it on the minute observation site 1 a of the subject 1.
Specifically, the acoustic lens 31 is a member provided with a recess 33 that forms a curved surface on one surface of a rectangular parallelepiped member. The recess 33 is formed on the surface of the acoustic lens 31 opposite to the surface on which the film member 32 is formed.
The ultrasonic waves generated at the irradiation point of the excitation pulsed light in the film member 32 propagate through the acoustic lens 31 and reach the depression 33, and from the surface of the depression 33 to the observation site 1 a of the subject 1. Radiated in the direction to go.
A coupling material 2 such as water is filled between the depression 33 and the subject 1 in the acoustic lens 31.
The acoustic lens 31 also focuses the ultrasonic wave (reflected ultrasonic wave) reflected by the observation site 1a onto the measurement light irradiation point on the film member 32.
前記膜部材３２で発生した超音波が前記被検体１の観測部位１ａに照射されて反射した前記反射超音波は，再び，前記カップリング材２及び前記音響レンズ３１を経て前記膜部材３２に戻ってくる。
そして，前記膜部材３２は，前記反射超音波を受波することにより，光弾性効果によって光反射率が変化する（屈折率が変化するといってもよい）超音波受波部の一例でもある。
このように，前記音響レンズ３１の表面に形成された前記膜部材３２は，超音波を発生させる超音波発生部及び超音波を受波する超音波受波部の両方を兼ねる部材である。
なお，前記音響レンズ３１には，表面が前記被検体１に対向する音響レンズ面（湾曲面）となっている窪みが設けられているが，前記膜部材３２は，当該窪みの表面（音響レンズ面）に沿って形成する構成とすることもできる。
The reflected ultrasonic waves reflected by the ultrasonic wave generated by the film member 32 being irradiated on the observation site 1a of the subject 1 return to the film member 32 again through the coupling material 2 and the acoustic lens 31. Come.
The film member 32 is also an example of an ultrasonic wave receiving unit that receives the reflected ultrasonic wave and changes its light reflectivity by the photoelastic effect (it may be said that the refractive index changes).
As described above, the film member 32 formed on the surface of the acoustic lens 31 serves as both an ultrasonic wave generating unit that generates ultrasonic waves and an ultrasonic wave receiving unit that receives ultrasonic waves.
The acoustic lens 31 is provided with a recess whose surface is an acoustic lens surface (curved surface) facing the subject 1, but the film member 32 is provided with a surface (acoustic lens) of the recess. The surface may be formed along the surface.
前記測定光照射部２０は，前記膜部材３２における前記反射超音波の集束点（前記励起用パルス光Ｂ１の照射点）に測定光Ｂ２を照射する測定光照射手段の一例である。
前記測定光照射部２０は，測定光Ｂ２を出力する測定光レーザ光源２１と，出射された測定光Ｂ２を前記膜部材３２上の前記反射超音波の集束点に変向させるミラー２２とを備えている。前記測定光レーザ光源２１は，例えば，波長６３３ｎｍのレーザ光を出力するＨｅ−Ｎｅレーザ等である。前記測定光Ｂ２の波長は，前記励起用パルス光Ｂ１の波長と異なる波長としている。
なお，前記測定光照射部２０は，少なくとも前記励起用パルス光Ｂ１が前記被検体１に照射されてから所定期間内において（例えば，１ｎｓ（ナノ秒）以上継続して）前記測定光Ｂ２を連続照射する。１回の前記測定光Ｂ２の照射の最短時間は，前記励起用パルス光Ｂ１が照射されてから，検出すべき前記反射超音波が前記膜部材３２に到達する可能性がある期間により定まる。
前記測定光検出部４０は，前記膜部材３２に照射された前記測定光Ｂ２の反射光（以下，反射測定光Ｂ２’という）を検出する測定光検出手段の一例である。
前記測定光検出部４０は，ミラー４１，光検出器４２及び高速オシロスコープ４３を備えている。
前記ミラー４１は，前記膜部材３２に対する前記測定光Ｂ２の正反射方向において前記反射測定光Ｂ２’を前記光検出器４２の方向へ変向させる。
前記光検出器４２は，前記反射測定光Ｂ２’の光電変換により前記反射測定光Ｂ１’の強度信号を生成し，その強度信号を前記高速オシロスコープ４３に出力するものである。
The measurement light irradiation unit 20 is an example of a measurement light irradiation unit that irradiates the measurement light B2 to the focused point of the reflected ultrasonic wave (the irradiation point of the excitation pulse light B1) on the film member 32.
The measurement light irradiation unit 20 includes a measurement light laser light source 21 that outputs the measurement light B2, and a mirror 22 that changes the emitted measurement light B2 to a focused point of the reflected ultrasonic wave on the film member 32. ing. The measurement light laser light source 21 is, for example, a He—Ne laser that outputs laser light having a wavelength of 633 nm. The wavelength of the measurement light B2 is different from the wavelength of the excitation pulse light B1.
The measurement light irradiating unit 20 continues the measurement light B2 within a predetermined period (for example, continuously for 1 ns (nanoseconds) or more) after at least the excitation pulse light B1 is applied to the subject 1. Irradiate. The shortest time for one irradiation of the measurement light B2 is determined by a period during which the reflected ultrasonic wave to be detected may reach the film member 32 after the excitation pulse light B1 is irradiated.
The measurement light detection unit 40 is an example of measurement light detection means for detecting reflected light of the measurement light B2 irradiated on the film member 32 (hereinafter referred to as reflected measurement light B2 ′).
The measurement light detector 40 includes a mirror 41, a photodetector 42, and a high-speed oscilloscope 43.
The mirror 41 changes the reflected measurement light B 2 ′ toward the photodetector 42 in the regular reflection direction of the measurement light B 2 with respect to the film member 32.
The photodetector 42 generates an intensity signal of the reflected measurement light B1 ′ by photoelectric conversion of the reflected measurement light B2 ′, and outputs the intensity signal to the high-speed oscilloscope 43.
図４は，前記光検出器４２によって検出される前記反射測定光Ｂ１’の強度信号の時系列変化の一例を表す図である。
図４に示されるように，前記反射測定光Ｂ１’の強度信号は，前記反射超音波（エコー）が前記膜部材３２に到達するごとに信号値が急変するピーク部Ｅ１，Ｅ２，Ｅ３，…が生じる。図４において，最初のピーク部Ｅ１は，前記音響レンズ３１と前記カップリング材２との界面で反射した反射超音波に相当し，２番目のピーク部Ｅ２は，前記被検体１の表面で反射した反射超音波に相当し，３番目以降のピーク部Ｅ２が，前記被検体１の内部状態を表す反射超音波に相当する。
２番目の前記ピーク部Ｅ２の発生時と３番目以降の前記ピーク部Ｅ３，Ｅ４，…の発生時との時間差，及び前記被検体１内での超音波の伝播速度から，前記被検体１の内部に存在する欠陥等の深さを特定できる。即ち，前記光検出器４２の検出信号は，前記被検体１の内部状態の観測信号である。
FIG. 4 is a diagram illustrating an example of a time-series change in the intensity signal of the reflected measurement light B1 ′ detected by the photodetector.
As shown in FIG. 4, the intensity signal of the reflected measurement light B1 ′ has peak portions E1, E2, E3,... Where the signal value changes suddenly every time the reflected ultrasonic wave (echo) reaches the film member 32. Occurs. In FIG. 4, the first peak E1 corresponds to the reflected ultrasonic wave reflected at the interface between the acoustic lens 31 and the coupling material 2, and the second peak E2 is reflected from the surface of the subject 1. The third and subsequent peak portions E2 correspond to the reflected ultrasound representing the internal state of the subject 1.
From the time difference between the time of occurrence of the second peak portion E2 and the time of occurrence of the third and subsequent peak portions E3, E4,..., And the propagation speed of the ultrasonic wave in the subject 1, The depth of defects and the like existing inside can be specified. That is, the detection signal of the photodetector 42 is an observation signal of the internal state of the subject 1.
前記高速オシロスコープ４３は，前記同期回路６１から前記パルス光出力開始信号が供給された時点から所定期間に，前記反射測定光Ｂ１’の強度信号を高速でサンプリングして一次記憶し，その強度信号の時系列変化を検出する装置である。例えば，前記高速オシロスコープ４３は，前記パルス光出力開始信号が供給された時点から前記反射測定光Ｂ１’の強度信号の変化が大きい前記ピーク部Ｅ１，Ｅ２，…（エコー）が検出されるまでの時間を検出し，その時間の情報を前記計算機６０に出力する。
前記高速オシロスコープ４３は，例えば，１〜１０ｐｓ程度のサンプリング周期での信号入力機能を有している。
そして，前記計算機６０は，前記高速オシロスコープ４３から得られる前記ピーク部Ｅ１，Ｅ２，…の検出時間の情報から，２番目の前記ピーク部Ｅ２の発生時と３番目以降の前記ピーク部Ｅ３，Ｅ４，…の発生時との時間差，及び前記被検体１内での超音波の伝播速度から，前記被検体１の内部に存在する欠陥等の深さを算出する。
The high-speed oscilloscope 43 samples the intensity signal of the reflected measurement light B1 ′ at a high speed for a predetermined period from the time when the pulse light output start signal is supplied from the synchronization circuit 61, and primarily stores the intensity signal. It is a device that detects time-series changes. For example, the high-speed oscilloscope 43 starts from the time when the pulse light output start signal is supplied until the peak portions E1, E2,... (Echo) where the change in the intensity signal of the reflected measurement light B1 ′ is large are detected. Time is detected, and information on the time is output to the computer 60.
The high-speed oscilloscope 43 has a signal input function at a sampling period of about 1 to 10 ps, for example.
Then, the computer 60 uses the information on the detection times of the peak portions E1, E2,... Obtained from the high-speed oscilloscope 43 to generate the second peak portion E2 and the third and subsequent peak portions E3, E4. ,..., And the depth of a defect or the like existing inside the subject 1 is calculated from the time difference from the time of occurrence and the propagation speed of ultrasonic waves in the subject 1.
前記Ｘ−Ｙステージ５１は，前記被検体１を支持し，前記超音波送受部Ｚ１に対する前記被検体１の相対位置（超音波の照射方向に対して直交する方向の位置）を変化させて位置決めする装置である。
前記ステージ制御部５２は，前記計算機６０からの位置決め指令に応じて，前記Ｘ−Ｙステージ５１による前記被検体１の支持位置を制御する回路である。
前記Ｘ−Ｙステージ５１によって前記被検体１における前記観測部位１ａの位置決めがなされるごとに，前記励起用パルス光Ｂ１及び前記測定光Ｂ２の照射と，前記測定光検出部４０による前記反射測定光Ｂ１’の検出と，前記計算機６０による前記被検体１の内部に存在する欠陥等の深さの算出とが行われる。
これにより，前記被検体１の内部の３次元方向の状態の分布が観測される。
前述したように，前記膜部材３２は，数ＧＨｚ以上の周波数（波長が数μｍ以下）の超音波を発生させる。また，前記光検出器４２によって検出される前記反射測定光Ｂ２’の強度は，前記膜部材３２における反射超音波の受波状況が高感度で反映される。
従って，超音波顕微鏡Ｘ１によれば，数μｍ以下のオーダー（例えば，サブμｍのオーダー）の高い空間分解能で被検体１の内部を高感度で観測できる。
The XY stage 51 supports the subject 1 and changes the relative position of the subject 1 with respect to the ultrasonic transmission / reception unit Z1 (position in a direction perpendicular to the ultrasonic wave irradiation direction) for positioning. It is a device to do.
The stage control unit 52 is a circuit that controls the support position of the subject 1 by the XY stage 51 in accordance with a positioning command from the computer 60.
Each time the observation site 1a in the subject 1 is positioned by the XY stage 51, the excitation pulse light B1 and the measurement light B2 are irradiated, and the reflected measurement light by the measurement light detector 40 is measured. The detection of B1 ′ and the calculation of the depth of a defect or the like existing inside the object 1 by the computer 60 are performed.
Thereby, the distribution of the state in the three-dimensional direction inside the subject 1 is observed.
As described above, the film member 32 generates ultrasonic waves having a frequency of several GHz or more (wavelength of several μm or less). In addition, the intensity of the reflected measurement light B2 ′ detected by the photodetector 42 reflects the reception status of the reflected ultrasonic wave at the film member 32 with high sensitivity.
Therefore, according to the ultrasonic microscope X1, the inside of the subject 1 can be observed with high sensitivity with a high spatial resolution on the order of several μm or less (for example, on the order of sub μm).
次に，図２を参照しつつ，前記超音波送受部Ｚ１の代わりに前記超音波顕微鏡Ｘ１に採用され得る超音波送受部Ｚ２について説明する。なお，図２において，図１に示された要素と同じ要素については同じ符号が付されている。
図２に示される前記超音波送受部Ｚ２は，音響レンズ３１’における表裏相対する２つの面に第１の膜部材３２ａ及び第２の膜部材３２ｂが形成された部材である。
前記音響レンズ３１’は，四角錐状の部材における，頂頭部が平面状にカットされ，底面に前記窪み３３が形成された部材である。また，前記音響レンズ３１は，その内部を超音波が少ない減衰で伝播され，また，前記測定光Ｂ２が透過するよう石英ガラスやサファイア等の硬質材料からなる透明体である。
また，前記第１の膜部材３２ａは，前記音響レンズ３１’における平面状の表面に形成され，前記第２の膜部材３２ｂは，前記窪み３３の表面に形成されている。
そして，前記励起用パルス光Ｂ１は，前記第１の膜部材３２ａの１点に照射される。
また，前記超音波送受部Ｚ２における前記第２の膜部材３２ｂと被検体１との間には，水などのカップリング材２が充填されている。
Next, an ultrasonic transmission / reception unit Z2 that can be employed in the ultrasonic microscope X1 instead of the ultrasonic transmission / reception unit Z1 will be described with reference to FIG. In FIG. 2, the same elements as those shown in FIG.
The ultrasonic transmission / reception unit Z2 shown in FIG. 2 is a member in which a first film member 32a and a second film member 32b are formed on two opposite surfaces of the acoustic lens 31 ′.
The acoustic lens 31 ′ is a member of a quadrangular pyramid member in which the top is cut into a flat shape and the depression 33 is formed on the bottom surface. The acoustic lens 31 is a transparent body made of a hard material such as quartz glass or sapphire so that the ultrasonic wave is propagated through the inside thereof with little attenuation and the measurement light B2 is transmitted.
The first film member 32 a is formed on the planar surface of the acoustic lens 31 ′, and the second film member 32 b is formed on the surface of the recess 33.
The excitation pulsed light B1 is applied to one point of the first film member 32a.
In addition, a coupling material 2 such as water is filled between the second film member 32b and the subject 1 in the ultrasonic transmission / reception unit Z2.
前記第１の膜部材３２ａも，前記膜部材３２（図１参照）と同様に，例えば，モリブデン，金，銅，アルミニウム等の金属の膜である。
そして，前記第１の膜部材３２ａも，前記励起用パルス光Ｂ１が照射されると，熱弾性効果により，そのパルス光Ｂ１とパルス幅が同じ熱弾性波を発生させる。即ち，前記第１の膜部材３２ａは，励起用パルス光Ｂ１が照射されることにより，熱弾性効果によって超音波を発する超音波発生部の一例である。
前記音響レンズ３１’は，前記第１の膜部材３２ａで発生した超音波を伝播させて前記被検体１の微小な観測部位１ａに集束させる。
前記第１の膜部材３２ａで発生した超音波が前記被検体１の観測部位１ａに照射されて反射した前記反射超音波は，再び，前記カップリング材２を経て前記第２の膜部材３２ｂに戻ってくる。
そして，前記第２の膜部材３２ｂは，前記反射超音波を受波することにより，光弾性効果によって光反射率が変化する（屈折率が変化するといってもよい）超音波受波部の一例である。
前記第２の膜部材３２ｂも，前記第１の膜部材３２ａと同じ材料が採用され得るが，水などの液体であることが通常である前記カップリング材２と接触するため，耐食性の高い金が採用されれば好適である。
このように，前記超音波送受部Ｚ２においては，超音波を発生させる超音波発生部として機能する前記第１の膜部材３２ａと，超音波を受波する超音波受波部として機能する前記第２の膜部材３２ｂとが個別に設けられている。このような構成も，本発明の実施形態の一例である。
Similarly to the film member 32 (see FIG. 1), the first film member 32a is also a film of a metal such as molybdenum, gold, copper, or aluminum.
The first film member 32a also generates thermoelastic waves having the same pulse width as the pulsed light B1 due to the thermoelastic effect when the excitation pulsed light B1 is irradiated. That is, the first film member 32a is an example of an ultrasonic wave generator that emits ultrasonic waves by the thermoelastic effect when irradiated with the excitation pulsed light B1.
The acoustic lens 31 ′ propagates the ultrasonic wave generated by the first film member 32 a and focuses it on the minute observation site 1 a of the subject 1.
The reflected ultrasonic waves that are reflected when the ultrasonic wave generated by the first film member 32a is applied to the observation site 1a of the subject 1 are again transmitted to the second film member 32b via the coupling material 2. Come back.
The second film member 32b is an example of an ultrasonic wave receiving unit that receives the reflected ultrasonic wave and changes its light reflectance by the photoelastic effect (it may be said that the refractive index changes). It is.
The second film member 32b may be made of the same material as that of the first film member 32a. However, since the second film member 32b is in contact with the coupling material 2 which is usually a liquid such as water, it has a high corrosion resistance. Is preferably used.
Thus, in the ultrasonic transmission / reception unit Z2, the first film member 32a that functions as an ultrasonic wave generation unit that generates ultrasonic waves and the first film member that functions as an ultrasonic wave reception unit that receives ultrasonic waves. Two membrane members 32b are provided individually. Such a configuration is also an example of an embodiment of the present invention.
また，前記超音波送受部Ｚ２においては，前記測定光Ｂ２が，前記音響レンズ３１’の側面から前記第２の膜部材３２ｂの表面（前記音響レンズ３１’に接触する面）に照射される。そして，前記第２の膜部材３２ｂに対する前記測定光Ｂ２の反射光である前記反射測定光Ｂ２’は前記光検出部４０（図１参照）へ導かれる。
前記超音波顕微鏡Ｘ１において，前記超音波送受部Ｚ１の代わりに図２に示される超音波送受部Ｚ２が採用されても，前記超音波送受部Ｚ１が採用された場合と同様の作用効果が得られる。
In the ultrasonic transmission / reception unit Z2, the measurement light B2 is applied to the surface of the second film member 32b (the surface in contact with the acoustic lens 31 ′) from the side surface of the acoustic lens 31 ′. The reflected measurement light B2 ′, which is the reflected light of the measurement light B2 with respect to the second film member 32b, is guided to the light detection unit 40 (see FIG. 1).
In the ultrasonic microscope X1, even when the ultrasonic transmission / reception unit Z2 shown in FIG. 2 is adopted instead of the ultrasonic transmission / reception unit Z1, the same effect as that obtained when the ultrasonic transmission / reception unit Z1 is adopted can be obtained. It is done.
また，前記測定光照射部２０が，前記第２の膜部材３２ｂにおいて表面プラズモン共鳴が生じる条件で前記測定光Ｂ２を前記第２の膜部材３２ｂに照射するものであれば好適である。
前記第２の膜部材３２ｂにおいて表面プラズモン共鳴が生じる条件は，前記第２の膜部材３２ｂの膜厚と，前記測定光Ｂ２の前記第２の膜部材３２ｂに対する入射角と，前記測定光Ｂ２の波長と，前記第２の膜部材３２ｂ及びそれと接する前記音響レンズ３１’の屈折率との組合せの条件であり，理論計算によって導出できることが知られている。
表面プラズモン共鳴状態にある物質（前記第２の膜部材３２ｂ）においては，その物質の表面上の僅かな屈折率の変化（光反射率の変化）により，照射された前記測定光Ｂ２の反射光の強度が極めて大きく変化する。そのため，前記第２の膜部材３２ｂにおける前記反射超音波の受波状況を，非常に高感度で（高いＳＮ比で）検出できる。
Further, it is preferable that the measurement light irradiating unit 20 irradiates the second film member 32b with the measurement light B2 under the condition that surface plasmon resonance occurs in the second film member 32b.
The conditions under which surface plasmon resonance occurs in the second film member 32b are as follows: the film thickness of the second film member 32b, the incident angle of the measurement light B2 with respect to the second film member 32b, and the measurement light B2 It is known that this is a condition of a combination of a wavelength and the refractive index of the second film member 32b and the acoustic lens 31 ′ in contact therewith, and can be derived by theoretical calculation.
In the substance in the surface plasmon resonance state (the second film member 32b), the reflected light of the measurement light B2 irradiated by a slight change in refractive index (change in light reflectance) on the surface of the substance. The strength of the material changes significantly. For this reason, it is possible to detect the reception state of the reflected ultrasonic wave in the second film member 32b with very high sensitivity (with a high S / N ratio).
次に，図３を参照しつつ，前記超音波送受部Ｚ１の代わりに前記超音波顕微鏡Ｘ１に採用され得る超音波送受部Ｚ３について説明する。なお，図３において，図１に示された要素と同じ要素については同じ符号が付されている。
図３に示される前記超音波送受部Ｚ３は，前記超音波送受部Ｚ１における前記音響レンズ３１の一部に，前記測定光Ｂ２を伝播させる導光路３１ａが形成されている。
前記導光路３１ａは，前記音響レンズ３１における前記膜部材３２（前記超音波受波部を兼ねる前記超音波発生部）が形成された面の表層部に形成されている。そして，前記導光路３１ａは，前記測定光Ｂ２を前記膜部材３２との界面に沿ってその界面に対して多重反射させつつ伝播させる。
前記導光路３１ａの入口及び出口には，前記測定光Ｂ２の導入用及び導出用の光ファイバ３４，３５が溶着されている。ここで，導入用の光ファイバ３４及び前記測定光レーザ光源２１が，前記導光路３１ａに前記測定光Ｂ２を入射させる前記測定光照射部２０となる。また，前記光検出器４２は，前記導光路３１ａを伝播した前記測定光（前記反射測定光Ｂ２’）の強度を検出する。これにより，前記膜部材３２の反射率の変化による前記反射測定光Ｂ２’の強度変化がより大きくなる。
前記導光路３１ａは，前記音響レンズ３１における他の部分よりも屈折率が僅かに高くなっている層である。例えば，前記音響レンズ３１の表面に１μｍ程度の厚みのチタンの膜を成膜して熱処理することに，チタンが前記音響レンズ３１の表面から深さ数μｍの表層に拡散する。その深さ数μｍの表層が，前記導光路３１ａとなる。
前記超音波顕微鏡Ｘ１において，前記超音波送受部Ｚ１の代わりに図３に示される超音波送受部Ｚ３が採用されれば，前記膜部材３２の光弾性効果による光反射率の変化，即ち，前記膜部材３２における反射超音波の受波状況を，非常に高感度で（高いＳＮ比で）検出できる。
Next, an ultrasonic transmission / reception unit Z3 that can be employed in the ultrasonic microscope X1 instead of the ultrasonic transmission / reception unit Z1 will be described with reference to FIG. In FIG. 3, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.
In the ultrasonic transmission / reception unit Z3 shown in FIG. 3, a light guide 31a for propagating the measurement light B2 is formed in a part of the acoustic lens 31 in the ultrasonic transmission / reception unit Z1.
The light guide path 31a is formed on the surface layer portion of the surface of the acoustic lens 31 on which the film member 32 (the ultrasonic wave generating portion also serving as the ultrasonic wave receiving portion) is formed. The light guide 31a propagates the measurement light B2 along the interface with the film member 32 while performing multiple reflection on the interface.
Optical fibers 34 and 35 for introducing and deriving the measurement light B2 are welded to the entrance and exit of the light guide 31a. Here, the introduction optical fiber 34 and the measurement light laser light source 21 serve as the measurement light irradiation unit 20 that causes the measurement light B2 to enter the light guide path 31a. The photodetector 42 detects the intensity of the measurement light (the reflected measurement light B2 ′) that has propagated through the light guide path 31a. Thereby, the intensity change of the reflected measurement light B2 ′ due to the change in the reflectance of the film member 32 becomes larger.
The light guide path 31 a is a layer having a slightly higher refractive index than other parts of the acoustic lens 31. For example, when a titanium film having a thickness of about 1 μm is formed on the surface of the acoustic lens 31 and heat-treated, titanium diffuses from the surface of the acoustic lens 31 to a surface layer having a depth of several μm. The surface layer having a depth of several μm becomes the light guide path 31a.
If the ultrasonic transmission / reception unit Z3 shown in FIG. 3 is adopted in the ultrasonic microscope X1 instead of the ultrasonic transmission / reception unit Z1, the change in the light reflectance due to the photoelastic effect of the film member 32, that is, the The reception status of the reflected ultrasonic wave in the film member 32 can be detected with very high sensitivity (with a high S / N ratio).
次に，図５を参照しつつ，本発明の第２実施形態に係る超音波顕微鏡Ｘ２について説明する。超音波顕微鏡Ｘ２は，前記超音波顕微鏡Ｘ１の応用例である。以下，前記超音波顕微鏡Ｘ１と異なる部分についてのみ説明する。なお，図５において，図１に示された要素と同じ要素については同じ符号が付されている。
超音波顕微鏡Ｘ２においては，前記パルスレーザ光源１１が，前記励起用パルス光Ｂ１の光源と，前記測定光Ｂ２の光源とを兼ねる。
即ち，前記パルスレーザ光源１１から出射されたパルス光は，ビームスプリッタ２１’により分光され，分光された光の一方を前記励起用パルス光Ｂ１とし，分光された光の他方をパルス状の測定光Ｂ２とする。
また，超音波顕微鏡Ｘ２においては，１箇所の前記観測部位１ａについて，前記同期回路６１が前記パルス光出力開始信号を一定周期で複数回連続して出力する。これにより，前記パルスレーザ光源１１は，前記励起用パルス光Ｂ１を連続して出力する（連続パルス光を出射する）光源と，その励起用パルス光Ｂ１の照射タイミングと同期してパルス状の前記測定光Ｂ２を出射する光源とを兼ねる光源となっている。なお，前記測定光Ｂ２用のパルス光源が，前記励起用パルス光Ｂ１の光源とは別個に設けられてもよい。
前記パルスレーザ光源１１及び前記ビームスプリッタ２１’により得られた連続パルス光である前記測定光Ｂ２は，ミラー２２’，後述する光路長調節部６０及び前記ミラー２２に反射して前記膜部材３２に照射される。
Next, an ultrasonic microscope X2 according to the second embodiment of the present invention will be described with reference to FIG. The ultrasonic microscope X2 is an application example of the ultrasonic microscope X1. Only the parts different from the ultrasonic microscope X1 will be described below. In FIG. 5, the same elements as those shown in FIG. 1 are denoted by the same reference numerals.
In the ultrasonic microscope X2, the pulse laser light source 11 serves as the light source for the excitation pulse light B1 and the light source for the measurement light B2.
That is, the pulsed light emitted from the pulsed laser light source 11 is split by the beam splitter 21 ', one of the split light is used as the excitation pulsed light B1, and the other of the split light is used as pulsed measurement light. Let B2.
Further, in the ultrasonic microscope X2, the synchronization circuit 61 continuously outputs the pulsed light output start signal a plurality of times at a constant cycle for one observation site 1a. Accordingly, the pulse laser light source 11 continuously outputs the excitation pulsed light B1 (emits continuous pulsed light) and the pulsed pulsed light in synchronization with the irradiation timing of the excitation pulsed light B1. The light source also serves as a light source that emits the measurement light B2. The pulse light source for the measurement light B2 may be provided separately from the light source for the excitation pulse light B1.
The measurement light B2, which is continuous pulse light obtained by the pulse laser light source 11 and the beam splitter 21 ′, is reflected by the mirror 22 ′, the optical path length adjusting unit 60 and the mirror 22, which will be described later, and is reflected on the film member 32. Irradiated.
また，超音波顕微鏡Ｘ２は，前記パルスレーザ光源１１から前記被検体１までの前記測定光Ｂ２の光路長を変更する光路長調節部６０を備えている。
前記光路長調節部６０は，前記測定光Ｂ２を反射するコーナーキューブミラー６１と，そのコーナーキューブミラー６１を前記測定光Ｂ２の光軸方向に直線移動させる移動ステージ６２とを備えている。
また，超音波顕微鏡Ｘ２は，前記同期回路６１から出力される前記パルス光出力開始信号を予め設定された時間だけ遅延させて前記計算機６０に供給する遅延回路６２を備えている。以下，前記遅延回路６２により前記パルス光出力開始信号に対して遅延処理が施された信号を遅延同期信号という。
前記遅延回路６２の遅延時間は，前記光路長調節部６０によって前記測定光Ｂ２の光路長が最短に設定されている状態で，前記被検体１の表面で反射した前記反射超音波に相当する前記ピーク部Ｅ２（２番目のエコー：図４参照）が前記光検出器４２で検出されるタイミング，又はそれより若干早いタイミングで，前記遅延同期信号が発生するように調節されている。
Further, the ultrasonic microscope X2 includes an optical path length adjustment unit 60 that changes the optical path length of the measurement light B2 from the pulse laser light source 11 to the subject 1.
The optical path length adjusting unit 60 includes a corner cube mirror 61 that reflects the measurement light B2, and a moving stage 62 that linearly moves the corner cube mirror 61 in the optical axis direction of the measurement light B2.
The ultrasonic microscope X2 includes a delay circuit 62 that delays the pulsed light output start signal output from the synchronization circuit 61 by a preset time and supplies the delayed signal to the computer 60. Hereinafter, a signal obtained by delaying the pulse light output start signal by the delay circuit 62 is referred to as a delay synchronization signal.
The delay time of the delay circuit 62 corresponds to the reflected ultrasound reflected from the surface of the subject 1 in a state where the optical path length of the measurement light B2 is set to the shortest by the optical path length adjusting unit 60. It is adjusted so that the delayed synchronization signal is generated at the timing when the peak portion E2 (second echo: see FIG. 4) is detected by the photodetector 42 or slightly earlier.
そして，超音波顕微鏡Ｘ２においては，前記光検出器４２及び前記計算機６０により，前記光路長調節部６０による前記測定光Ｂ２の光路長の変更に応じて，前記膜部材３２に照射された前記測定光Ｂ２の反射光の強度の検出信号をサンプリングする。
サンプリングされた前記反射測定光Ｂ２’の強度信号に一時的な変動（前記ピーク部Ｅ３，Ｅ４，…に相当）が表れたときの前記測定光Ｂ２の光路長は，前記ピーク部Ｅ３，Ｅ４の検出時間に換算できる。
従って，前記計算機６０は，サンプリングした前記反射測定光Ｂ２’の強度信号に一時的変動が生じたときの前記測定光Ｂ２の光路長に基づいて，前記被検体１の内部に存在する欠陥等の深さを算出する。
In the ultrasonic microscope X2, the measurement irradiated to the film member 32 by the optical detector 42 and the computer 60 according to the change in the optical path length of the measuring light B2 by the optical path length adjusting unit 60. The detection signal of the intensity of the reflected light of the light B2 is sampled.
The optical path length of the measurement light B2 when a temporary fluctuation (corresponding to the peak portions E3, E4,...) Appears in the sampled intensity signal of the reflected measurement light B2 ′ is the peak portions E3, E4. Can be converted into detection time.
Therefore, the calculator 60 determines the defects etc. present in the subject 1 based on the optical path length of the measurement light B2 when the intensity variation of the sampled reflected measurement light B2 ′ is temporarily changed. Depth is calculated.
例えば，前記光路長調節部６０は，前記コーナーキューブミラー６１を一定速度で移動させることにより，前記測定光Ｂ２の光路長を一定速度で変化させる。さらに，前記計算機６０が，一定周期で発生する前記遅延同期信号が入力されるごとに前記光検出器４２の検出信号をサンプリングする。
ここで，前記光路長調節部６０において，前記移動ステージ６２が前記コーナーキューブミラー６１を１５０ｍｍ移動させれば，前記測定光Ｂ２の光路長が３００ｍｍ変化する。光路長３００ｍｍの差は，前記膜部材３２への前記測定光Ｂ２の照射タイミングの時間差に換算すれば約１ｎｓ（ナノ秒）の時間差となる。
また，前記光路長調節部６０が，前記パルスレーザ光１１によるパルス光の出力ごとに前記コーナーキューブミラー６１を１００μｍずつ移動させれば，前記測定光Ｂ２の光路長が２００μｍずつ変化し，前記光検出器４２の検出信号（前記反射測定光Ｂ２’の強度信号）のサンプリングの時間分解能は０．６７ｐｓ（ピコ秒）となる。
このように，約０．７ｐｓの時間分解能及び約１ｎｓの時間の範囲で前記光検出器４２の検出信号をサンプリングできれば，前記被検体１の内部状態を十分な空間分解能で観察できる。
また，前記コーナーキューブミラー６１を１０μｍずつ１５０ｍｍ移動させることは，例えば，前記移動ステージ６２に例えばステッピングモータのようなアクチュエータを採用すれば特に難しいことではない。
従って，超音波顕微鏡Ｘ２によれば，特に時間分解能の高い前記高速オシロスコープ４３を採用しなくても，前記被検体１の内部に存在する欠陥や不純物等の深さを高い分解能で特定できる。
なお，以上に示した実施形態は，前記計算機６０によって前記反射測定光Ｂ２’の強度信号（前記光検出器４２の出力信号）の変動を直接的に検出する例であるが，他の実施形態も考えられる。例えば，前記反射測定光Ｂ２’の強度信号の変動が微小である場合，前記パルスレーザ光源１１の出力光（前記測定光Ｂ２）に対して周期的な強度変調を施すとともに，前記計算機６０により，前記光検出器４２の出力信号から，前記測定光Ｂ２の強度変調周期と同期した周期成分を抽出し，その抽出成分の変動を検出することも考えられる。これにより，信号検出のＳＮ比を高めることができる。
For example, the optical path length adjusting unit 60 changes the optical path length of the measurement light B2 at a constant speed by moving the corner cube mirror 61 at a constant speed. Further, the computer 60 samples the detection signal of the photodetector 42 each time the delayed synchronization signal generated at a constant period is input.
Here, in the optical path length adjusting unit 60, if the moving stage 62 moves the corner cube mirror 61 by 150 mm, the optical path length of the measuring light B2 changes by 300 mm. The difference in the optical path length of 300 mm is a time difference of about 1 ns (nanosecond) when converted into a time difference in the irradiation timing of the measurement light B2 to the film member 32.
Further, if the optical path length adjusting unit 60 moves the corner cube mirror 61 by 100 μm for each output of the pulsed light by the pulsed laser light 11, the optical path length of the measuring light B2 changes by 200 μm, and the light The sampling time resolution of the detection signal of the detector 42 (intensity signal of the reflected measurement light B2 ′) is 0.67 ps (picosecond).
Thus, if the detection signal of the photodetector 42 can be sampled within a time resolution of about 0.7 ps and a time of about 1 ns, the internal state of the subject 1 can be observed with a sufficient spatial resolution.
Further, it is not particularly difficult to move the corner cube mirror 61 by 10 μm by 150 mm if, for example, an actuator such as a stepping motor is used for the moving stage 62.
Therefore, according to the ultrasonic microscope X2, the depth of defects, impurities, and the like existing inside the subject 1 can be specified with high resolution without using the high-speed oscilloscope 43 with particularly high time resolution.
The embodiment described above is an example in which the calculator 60 directly detects the fluctuation of the intensity signal of the reflected measurement light B2 ′ (the output signal of the photodetector 42). Is also possible. For example, when the fluctuation of the intensity signal of the reflected measurement light B2 ′ is very small, the output light of the pulse laser light source 11 (the measurement light B2) is subjected to periodic intensity modulation, and the calculator 60 It is also conceivable to extract a periodic component synchronized with the intensity modulation period of the measurement light B2 from the output signal of the photodetector 42 and detect the fluctuation of the extracted component. Thereby, the signal-to-noise ratio of signal detection can be increased.
ところで，本発明の他の実施形態としては，例えば，図５に示された前記超音波顕微鏡Ｘ２に，図２に示された前記超音波送受部Ｚ２や図３に示された前記超音波送受部Ｚ３が採用されたもの等が考えられる。 Incidentally, as another embodiment of the present invention, for example, the ultrasonic transmission / reception unit Z2 shown in FIG. 2 or the ultrasonic transmission / reception shown in FIG. 3 is added to the ultrasonic microscope X2 shown in FIG. The thing etc. which the part Z3 was employ | adopted are considered.
次に，図６を参照しつつ，前記超音波送受部Ｚ１の代わりに前記超音波顕微鏡Ｘ１，Ｘ２に採用され得る超音波送受部Ｚ４について説明する。なお，図６において，図１に示された要素と同じ要素については同じ符号が付されている。
図６に示される前記超音波送受部Ｚ４は，前記膜部材３２の表面に固体からなる部材３６が接合されている点が，前記超音波送受部Ｚ１と異なる。以下，部材３６のことを固体接合部材３６と称する。
前記固体接合部材３６は，超音波の発生部である前記膜部材３２における前記励起用パルス光Ｂ１の入射面に接合された固体からなる部材である。この固体接合部材３６は，前記膜部材３２における前記励起用パルス光Ｂ１の入射面の変位（熱膨張変位）を拘束するためのものである。ここで，前記膜部材３２における前記固体接合部材３６が接合される面（図６における上側の面）は，前記被検体１に向かう側と反対側の面である。
また，前記固体接合部材３６は，前記膜部材３２に入射する前記励起用パルス光Ｂ１を透過させる透明な部材である。例えば，前記固体接合部材３６は，石英ガラスやサファイア等からなる透明な部材である。
Next, an ultrasonic transmission / reception unit Z4 that can be employed in the ultrasonic microscopes X1 and X2 instead of the ultrasonic transmission / reception unit Z1 will be described with reference to FIG. In FIG. 6, the same elements as those shown in FIG.
The ultrasonic transmission / reception unit Z4 shown in FIG. 6 is different from the ultrasonic transmission / reception unit Z1 in that a solid member 36 is bonded to the surface of the film member 32. Hereinafter, the member 36 is referred to as a solid bonding member 36.
The solid joining member 36 is a member made of a solid joined to the incident surface of the excitation pulsed light B1 in the film member 32 which is an ultrasonic wave generating portion. The solid bonding member 36 is for restricting the displacement (thermal expansion displacement) of the incident surface of the excitation pulsed light B1 in the film member 32. Here, the surface of the membrane member 32 to which the solid bonding member 36 is bonded (the upper surface in FIG. 6) is the surface opposite to the side facing the subject 1.
The solid bonding member 36 is a transparent member that transmits the excitation pulsed light B <b> 1 incident on the film member 32. For example, the solid joining member 36 is a transparent member made of quartz glass, sapphire, or the like.
図７は，励起された膜部材７１からの超音波の発生状態を軸対象モデルに基づく計算機でのシミュレーションを行った結果を表す図である。なお，図７のシミュレーション結果は，ガラス製の基材７０の表面に接合された前記膜部材７１に，０．５ナノ秒のパルス幅の前記励起用パルス光Ｂ１の照射に相当する応力が与えられた条件下でのシミュレーション結果である。
図７において，（ａ）の図は，前記膜部材７１における前記基材７０との接合面に対して反対側の面（図７における上側の面）が自由表面である場合のシミュレーション結果である。一方，（ｂ）の図は，前記膜部材７１における前記基材７０との接合面に対して反対側の面が，ガラス製の拘束体７２の接合によってその変位が拘束された状態である場合のシミュレーション結果である。
また，図７に示される前記基材７０において，黒のベタ塗りではない部分（模様が生じている部分）が，超音波（弾性波）が生じている部分である。
FIG. 7 is a diagram showing a result of performing a simulation with a computer based on the axial target model of the generation state of the ultrasonic waves from the excited film member 71. The simulation result of FIG. 7 shows that the film member 71 bonded to the surface of the glass substrate 70 is given a stress corresponding to the irradiation of the excitation pulsed light B1 having a pulse width of 0.5 nanoseconds. It is a simulation result under specified conditions.
In FIG. 7, (a) is a simulation result when the opposite surface (upper surface in FIG. 7) of the membrane member 71 with respect to the bonding surface with the base material 70 is a free surface. . On the other hand, in the figure of (b), the surface of the membrane member 71 opposite to the bonding surface with the base material 70 is in a state in which the displacement is constrained by the bonding of the glass restraint 72. This is a simulation result.
Further, in the base material 70 shown in FIG. 7, a portion that is not solid black (a portion where a pattern is generated) is a portion where an ultrasonic wave (elastic wave) is generated.
図７に示されるように，前記膜部材７１の一方の面が自由表面である場合，主としてその自由表面で熱膨張変位が生じて超音波が放散し，その自由面の反対側の面から前記基材７０へ進入する超音波の進入深さが比較的浅くなる。一方，前記膜部材７１の一方の面が前記拘束体７２により拘束されている場合，超音波の放散ロスが減り，前記基材７０へ進入する超音波の強度が増して前記基材７０への進入深さが深くなる。
このように，前記拘束体７２が設けられることにより，前記基材７０の方向へ向かう超音波の発生効率を高めることができる。
そして，前記超音波送受部Ｚ４における前記固体接合部材３６は，図７における前記拘束体７２の機能を果たす。
従って，前記超音波顕微鏡Ｘ１，Ｘ２において，前記超音波送受部Ｚ１の代わりに前記超音波送受部Ｚ４が採用されることにより，前記膜部材３２における前記励起用パルス光Ｂ１の入射面の変位の拘束力が高くなり，前記音響レンズ３１を通じて前記被検体１に向かう超音波の発生効率を高めることができる。
また，前記固体接合部材３６は，前記膜部材３２よりもヤング率の大きい部材であることが望ましい。これにより，前記膜部材３２における前記励起用パルス光Ｂ１の入射面の変位の拘束力がより高くなり，前記被検体１に向かう超音波の発生効率をより高めることができる。
As shown in FIG. 7, when one surface of the film member 71 is a free surface, thermal expansion displacement occurs mainly on the free surface, and ultrasonic waves are dissipated. The penetration depth of the ultrasonic waves entering the base material 70 is relatively shallow. On the other hand, when one surface of the film member 71 is constrained by the restraining body 72, the loss of ultrasonic waves is reduced, and the intensity of the ultrasonic waves entering the base material 70 is increased. The depth of entry increases.
Thus, by providing the restraining body 72, it is possible to increase the generation efficiency of ultrasonic waves directed toward the base material 70.
And the said solid joining member 36 in the said ultrasonic transmission / reception part Z4 fulfill | performs the function of the said restraint body 72 in FIG.
Accordingly, in the ultrasonic microscopes X1 and X2, the ultrasonic transmission / reception unit Z4 is employed in place of the ultrasonic transmission / reception unit Z1, so that the displacement of the incident surface of the excitation pulse light B1 in the film member 32 is reduced. The restraining force is increased, and the generation efficiency of the ultrasonic wave toward the subject 1 through the acoustic lens 31 can be increased.
The solid joining member 36 is preferably a member having a larger Young's modulus than the membrane member 32. Thereby, the restraining force of the displacement of the incident surface of the excitation pulsed light B1 in the film member 32 becomes higher, and the generation efficiency of the ultrasonic wave toward the subject 1 can be further increased.
また，上記実施形態以外にも，被検体に対向する音響レンズ面を通じて入射した被検体からの反射超音波を超音波受波部に集光させる音響レンズを具備し，超音波発生部が，音響レンズ面に沿って形成された構成とすることもできる。
なお，音響レンズは，超音波発生部で発生した超音波を放射して被検体に収束させる第１の音響レンズ面と，被検体で反射した反射超音波を放射して超音波受波部に収束させる第２の音響レンズ面とを有する構成とすることもできる。
このような構成によっても，前記被検体及び前記超音波受波部における超音波の収束位置の応力を高めることができ，前記被検体の内部状態をより好感度で（（高いＳＮ比で）検出することができる。
In addition to the above-described embodiment, there is provided an acoustic lens for condensing reflected ultrasonic waves from the subject incident through the acoustic lens surface facing the subject on the ultrasonic wave receiving unit, and the ultrasonic wave generating unit It can also be set as the structure formed along the lens surface.
The acoustic lens radiates the ultrasonic wave generated by the ultrasonic wave generation unit and converges it on the subject, and radiates the reflected ultrasonic wave reflected by the subject to the ultrasonic wave reception unit. It can also be set as the structure which has the 2nd acoustic lens surface made to converge.
Even with such a configuration, it is possible to increase the stress at the convergence position of the ultrasonic waves in the subject and the ultrasonic wave receiving section, and detect the internal state of the subject with higher sensitivity (with a high S / N ratio). can do.
本発明は，超音波顕微鏡への利用が可能である。 The present invention is applicable to an ultrasonic microscope.
Ｘ１，Ｘ２：超音波顕微鏡
Ｚ１〜Ｚ４：超音波送受部
１ ：被検体
１ａ：観測部位
２ ：カップリング材
１０：励起用パルス光照射部
１１：パルスレーザ光源
２０：測定光照射部
２１：測定光レーザ光源
３１，３１’，３１ａ：音響レンズ
３１ａ：導光路
３２：膜部材
３２ａ：第１の膜部材
３２ｂ：第２の膜部材
３３：窪み
３６：固体接合部材
４０：測定光検出部
４２：光検出器
４３：高速オシロスコープ
５１：Ｘ−Ｙステージ
５２：ステージ制御部
６０：計算機
６１：同期回路
６２：遅延回路
Ｂ１：励起用パルス光
Ｂ２：測定光
Ｂ２’：反射測定光
X1, X2: Ultrasonic microscopes Z1 to Z4: Ultrasonic transmission / reception unit 1: Subject 1a: Observation site 2: Coupling material 10: Excitation pulse light irradiation unit 11: Pulse laser light source 20: Measurement light irradiation unit 21: Measurement Optical laser light sources 31, 31 ′, 31a: acoustic lens 31a: light guide path 32: film member 32a: first film member 32b: second film member 33: depression 36: solid bonding member 40: measurement light detector 42: Photodetector 43: High-speed oscilloscope 51: XY stage 52: Stage controller 60: Computer 61: Synchronization circuit 62: Delay circuit B1: Pulse light for excitation B2: Measurement light B2 ′: Reflection measurement light
Claims (7)
励起用パルス光が照射されることにより、熱弾性効果によって超音波を発する超音波発生部と、
前記励起用パルス光を前記超音波発生部に照射する励起用パルス光照射手段と、
前記超音波発生部で発生した超音波が前記被検体に照射されて反射した前記反射超音波を受波することにより，光弾性効果によって光反射率が変化する超音波受波部と、
前記超音波受波部に測定光を照射する測定光照射手段と、
前記超音波受波部に照射された前記測定光の反射光を検出する測定光検出手段と、
表面に前記超音波受波部が形成され、該超音波発生部で発生した超音波を前記被検体の一部に集束させる音響レンズと、を具備し、
前記超音波発生部が前記超音波受波部を兼ね、
前記音響レンズにおける、前記超音波受波部を兼ねる前記超音波発生部が形成された面を含む当該音響レンズの表層部に、前記測定光を前記超音波発生部との界面に沿ってその界面に対して多重反射させつつ伝播させる導光路が形成され、
前記測定光照射手段が、前記導光路に前記測定光を入射させ、
前記測定光検出手段が、前記導光路を伝播した前記測定光を検出してなることを特徴とする超音波顕微鏡。 An ultrasonic microscope that obtains an observation signal inside the subject by irradiating the subject with ultrasonic waves and detecting reflected ultrasonic waves from the subject,
An ultrasonic generator that emits ultrasonic waves by a thermoelastic effect by being irradiated with excitation light,
Excitation pulsed light irradiating means for irradiating the ultrasonic wave generating unit with the excitation pulsed light;
An ultrasonic wave receiving unit whose light reflectivity is changed by a photoelastic effect by receiving the reflected ultrasonic wave reflected by the ultrasonic wave generated by the ultrasonic wave generated by the subject; and
Measurement light irradiation means for irradiating the ultrasonic wave receiving part with measurement light; and
Measurement light detection means for detecting reflected light of the measurement light applied to the ultrasonic wave receiving unit;
An acoustic lens having the ultrasonic wave receiving portion formed on a surface thereof, and focusing the ultrasonic wave generated by the ultrasonic wave generating portion on a part of the subject ;
The ultrasonic wave generation unit also serves as the ultrasonic wave reception unit,
In the acoustic lens, on the surface layer portion of the acoustic lens including the surface on which the ultrasonic wave generation unit that also serves as the ultrasonic wave reception unit is formed, the measurement light is interfaced along the interface with the ultrasonic wave generation unit. A light guide path that propagates while reflecting multiple times is formed,
The measurement light irradiation means causes the measurement light to enter the light guide,
The ultrasonic microscope, wherein the measurement light detection means detects the measurement light propagated through the light guide .
前記測定光検出手段が、前記超音波受波部に照射された前記測定光の反射光の強度の時系列変化を検出するものである請求項１〜４のいずれかに記載の超音波顕微鏡。 The measurement light irradiation means continuously irradiates the measurement light within a predetermined period after at least the excitation pulse light is irradiated on the subject.
The ultrasonic microscope according to any one of claims 1 to 4 , wherein the measurement light detection means detects a time-series change in the intensity of reflected light of the measurement light irradiated on the ultrasonic wave receiving unit.
前記測定光照射手段が、前記励起用パルス光の照射タイミングと同期してパルス状の前記測定光を出力するパルス測定光出力手段と、該パルス測定光出力手段から前記被検体までの前記測定光の光路長を変更する光路長変更手段と、を具備し，
前記測定光検出手段が、前記光路長変更手段による前記測定光の光路長の変更に応じて前記超音波受波部に照射された前記測定光の反射光の強度の検出信号をサンプリングするものである請求項１〜５のいずれかに記載の超音波顕微鏡。 The excitation pulsed light irradiation means continuously irradiates the excitation pulsed light,
The measurement light irradiation means outputs a pulsed measurement light output in synchronization with the irradiation timing of the excitation pulse light, and the measurement light from the pulse measurement light output means to the subject. An optical path length changing means for changing the optical path length of
The measurement light detection means samples a detection signal of the intensity of the reflected light of the measurement light irradiated on the ultrasonic wave receiving unit according to the change of the optical path length of the measurement light by the optical path length change means. The ultrasonic microscope according to any one of claims 1 to 5 .
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