JP7252887B2 - Photoacoustic wave measurement device - Google Patents

Description

TECHNICAL FIELD The present invention relates to measurement using an apparatus that outputs laser light of a plurality of wavelengths as pulses.

Conventionally, it is known to perform measurement (for example, measurement of oxygen saturation in blood) based on a response (for example, absorption coefficient) obtained by irradiating an object to be measured (for example, a living body) with pulsed light. . It is also known that the response obtained from the object to be measured differs depending on the wavelength of the pulsed light. Therefore, it is desired to irradiate an object to be measured with pulsed light beams having a plurality of wavelengths from the viewpoint of improving measurement accuracy. At that time, if the time from irradiating a certain point P of the object to be measured with pulsed light of a certain wavelength to irradiating the point P with pulsed light of another wavelength becomes longer, the movement of the object to be measured (for example, body movement) causes deterioration in measurement accuracy.

However, there is no known technique for irradiating pulsed light of a certain wavelength and then immediately irradiating pulsed light of another wavelength. For example, Patent Documents 1, 2, and 3 describe that laser beams of different wavelengths are combined, but after irradiating pulsed light of a certain wavelength, pulses of another wavelength are immediately applied. It is not about irradiating light.

JP 2011-107094 A WO2017/138619 JP 2016-101393 A

Accordingly, an object of the present invention is to perform photoacoustic wave measurement by irradiating an object to be measured with pulsed light of a certain wavelength and then immediately irradiating it with pulsed light of another wavelength.

A photoacoustic wave measurement apparatus according to the present invention includes a laser light output device that outputs laser light, and a measurement unit that measures the measurement target based on a photoacoustic wave generated in the measurement target by the laser light, A laser light output device includes a pulse laser output unit for outputting a laser light of a predetermined wavelength as a first pulse; an optical path determining section for determining and outputting an optical path; a wavelength changing section for receiving traveling light traveling through each of the plurality of optical paths, changing the wavelengths to different wavelengths for output; and combining the outputs of the wavelength changing sections. and a multiplexer.

According to the photoacoustic wave measurement device configured as described above, the laser light output device outputs laser light. A measurement unit measures the measurement target based on photoacoustic waves generated in the measurement target by the laser beam. According to the laser light output device, the pulse laser output section outputs laser light of a predetermined wavelength as the first pulse. An optical path determination unit receives the first pulse, determines an optical path for each of the first pulses, and outputs the optical path to any one of a plurality of optical paths. A wavelength changing unit receives traveling light traveling through each of the plurality of optical paths, changes the wavelength to a different wavelength, and outputs the light. A multiplexer multiplexes the outputs of the wavelength changing units.

In addition, the photoacoustic wave measurement apparatus according to the present invention includes an ultrasonic pulse output unit that outputs an ultrasonic pulse, and the measurement unit further measures a reflected wave of the ultrasonic pulse reflected by the measurement target. can be

In the photoacoustic wave measuring device according to the present invention, the first pulse has a predetermined frequency, and the optical path determination unit selects the predetermined frequency from each of the plurality of optical paths. A second pulse having a frequency divided by the number and having different phases may be output.

In addition, in the photoacoustic wave measurement apparatus according to the present invention, the multiplexer may output the third pulse having the predetermined frequency.

In addition, in the photoacoustic wave measurement apparatus according to the present invention, the pulse laser output unit may be an excitation laser.

In addition, in the photoacoustic wave measurement apparatus according to the present invention, the optical path determination unit may be an acousto-optic modulator or an acousto-optic deflector.

In the photoacoustic wave measuring device according to the present invention, the wavelength changing portion has polarization inversion portions arranged at predetermined intervals through which the traveling light propagates, and the predetermined intervals are equal to the traveling wavelengths. It may be different for each light.

In the photoacoustic wave measuring device according to the present invention, the wavelength changing portion has a nonlinear optical crystal substrate on which the polarization inversion portion is formed, and the centroid of the polarization inversion portion is the nonlinear optical crystal substrate. They may be arranged on a straight line parallel to the x-axis.

In addition, in the photoacoustic wave measuring device according to the present invention, the centroid of the polarization inversion portion may be arranged on a straight line parallel to the traveling direction of the traveling light.

In the photoacoustic wave measurement device according to the present invention, the wavelength changing section may have one nonlinear optical crystal substrate on which all of the polarization inversion sections are formed.

In the photoacoustic wave measuring device according to the present invention, the wavelength changing section has a nonlinear optical crystal substrate on which the polarization inversion section is formed, and the nonlinear optical crystal substrate is provided for each traveling light that propagates. You can make it as it is.

In the photoacoustic wave measurement device according to the present invention, the wavelength changing section may have a nonlinear optical crystal through which the traveling light propagates.

The photoacoustic wave measurement apparatus according to the present invention may include an optical fiber that receives the output of the multiplexer at one end and outputs the output from the other end.

The photoacoustic wave measurement apparatus according to the present invention may include a timing control section that matches the output of the optical path determination section with the timing of the output of the first pulse.

In the photoacoustic wave measuring device according to the present invention, the optical path determination unit receives the first pulse, determines the optical path to any one of a plurality of optical paths for each of the first pulses, and outputs and a first acousto-optic modulator that receives the output of the first acousto-optic modulator and determines an optical path to any one of one or more optical paths for each pulse of the output of the first acousto-optic modulator. and a second acousto-optic modulator that outputs as

In the photoacoustic wave measuring device according to the present invention, the first acousto-optic modulator diffracts or rectilinearly outputs each of the first pulses, and the second acousto-optic modulator outputs the It is also possible to receive the first pulse that has traveled straight, diffract it, or make it travel straight and output it, and receive the diffracted first pulse, make it travel straight, and then output it.

In the photoacoustic wave measuring device according to the present invention, the first acousto-optic modulator diffracts or rectilinearly outputs each of the first pulses, and the second acousto-optic modulator outputs the The diffracted first pulse may be received and diffracted or propagated straight to be output, and the straight first pulse may be received and propagated straight to be output.

In the photoacoustic wave measuring device according to the present invention, the first acousto-optic modulator diffracts or rectilinearly outputs each of the first pulses, and the second acousto-optic modulator outputs the Each pulse of the output of the first acousto-optic modulator may be diffracted or straightened and output.

1 is a diagram showing the configuration of a laser light output device 1 according to a first embodiment; FIG. 4 is a plan view of the wavelength changing section 14 according to the first embodiment; FIG. 4 is a timing chart of a first pulse P1, a second pulse (before wavelength conversion) P2a, a second pulse (after wavelength conversion) P2b, and a third pulse (after filtering) P3b according to the first embodiment; FIG. 4 is a plan view of a wavelength changing section 14 according to a modification of the first embodiment; It is a figure which shows the structure of the laser-light output apparatus 1 concerning 2nd embodiment. It is a figure which shows the structure of the laser-light output apparatus 1 concerning 3rd embodiment. 9 is a timing chart of a first pulse P1, a second pulse (before wavelength conversion) P2a, a second pulse (after wavelength conversion) P2b, and a third pulse (after filtering) P3b according to the third embodiment; It is a figure which shows the structure of the laser-light output apparatus 1 concerning 4th embodiment. FIG. 11 is an enlarged view of the vicinity of an optical path determination unit (a first acousto-optic modulator (AOM) 12a and a second acousto-optic modulator (AOM) 12b) in the laser light output device 1 according to the fourth embodiment; It is a figure which shows the structure of the laser-light output apparatus 1 concerning 5th embodiment. FIG. 11 is an enlarged view of the vicinity of an optical path determination unit (a first acousto-optic modulator (AOM) 12a and a second acousto-optic modulator (AOM) 12b) in the laser light output device 1 according to the fifth embodiment; FIG. 13 is an enlarged view of the vicinity of the optical path determining section (the first acousto-optic modulator (AOM) 12a and the second acousto-optic modulator (AOM) 12b) in the laser light output device 1 according to the modification of the fourth embodiment; FIG. 10 is a functional block diagram showing the configuration of a photoacoustic wave measurement device 100 according to a sixth embodiment of the present invention; FIG. 11 is a functional block diagram showing the configuration of a photoacoustic wave measurement device 100 according to a seventh embodiment of the present invention;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 is a diagram showing the configuration of a laser light output device 1 according to a first embodiment. FIG. 2 is a plan view of the wavelength changing section 14 according to the first embodiment. FIG. 3 is a timing chart of the first pulse P1, second pulse (before wavelength conversion) P2a, second pulse (after wavelength conversion) P2b, and third pulse (after filtering) P3b according to the first embodiment. In FIG. 3, the width of the line indicating the pulse and the type of line (solid line or broken line) are changed according to the wavelength.

The laser light output device 1 according to the first embodiment includes an excitation laser (pulse laser output unit) 10, an optical attenuator (ATT) 11, an acousto-optic modulator (optical path determination unit) (AOM) 12, a wavelength change unit ( PPLN) 14 , mirror 15 , dichroic mirror (multiplexer) (DCM) 16 , filter (F) 17 , optical fiber (MMF) 18 and timing control circuit (timing control section) 19 .

An excitation laser (pulse laser output unit) 10 outputs laser light with a predetermined wavelength W1 [nm] as a first pulse P1 (see FIG. 3) with a predetermined frequency (for example, 2 kHz). The excitation laser 10 is, for example, a Yb:YAG laser.

An optical attenuator (ATT) 11 attenuates the first pulse P1 and supplies it to an acoustooptic modulator 12 .

An acousto-optic modulator (optical path determination unit) (AOM) 12 receives the first pulse P1, determines the optical path of each of the first pulses P1 to one of the plurality of optical paths OP1 and OP2, and outputs the optical path. .

For example, referring to FIGS. 1 and 3, when the acoustooptic modulator 12 receives odd-numbered (1st, 3rd, 5th, . . . ) pulses of the first pulse P1, the acoustooptic modulator 12 receives an acoustic give no waves. Then, the odd-numbered pulses of the first pulse P1 pass straight through the acousto-optic modulator 12 (optical path OP1).

Also, when the acoustooptic modulator 12 receives the even-numbered (2nd, 4th, 6th, . Then, even-numbered pulses of the first pulse P1 pass through the acousto-optic modulator 12 while being diffracted to some extent (optical path OP2).

However, when the acousto-optic modulator 12 receives an odd-numbered pulse of the first pulse P1, the acoustic wave (angular frequency ω1) (where ω1 is different from ω2) may be applied to the acousto-optic modulator 12. .

Accordingly, the acousto-optic modulator 12 has a frequency (1 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of the plurality of optical paths (2) from each of the plurality of optical paths OP1 and OP2. , and a second pulse (before wavelength conversion) P2a, which are pulses with phases different from each other by 180 degrees.

A timing control circuit (timing control section) 19 matches the output of the acoustooptic modulator (optical path determining section) 12 to the output timing of the first pulse P1. The timing results are as described above with reference to FIG. The timing control circuit 19 receives a signal synchronized with the output timing of the first pulse P1 from the excitation laser (pulse laser output unit) 10, and controls the output timing of the acoustooptic modulator 12 based on this signal. .

A wavelength changing unit (PPLN) 14 receives traveling light (that is, the second pulse P2a) traveling through each of the plurality of optical paths OP1 and OP2, changes the wavelength to a different wavelength, and outputs the light. The output of the wavelength changing section 14 is the second pulse (after wavelength conversion) P2b.

Referring to FIG. 3, wavelength changing unit 14 receives the second pulse P2a that has traveled along optical path OP1 (wavelength W1 [nm]) and converts it into a second pulse P2b (wavelength W2 [nm]). . Further, the wavelength changing unit 14 receives the second pulse P2a (wavelength W1 [nm]) that has traveled through the optical path OP2 and converts it into a second pulse P2b (wavelength W3 [nm]).

Referring to FIG. 2, wavelength changing portion 14 has LN crystal substrate 142 and polarization inversion portion 144 . 2, unlike FIG. 1, the x-axis direction of the LN crystal substrate 142 is shown parallel to the horizontal direction of the paper for convenience of illustration.

The polarization reversal portion 144 propagates the traveling light (which is the second pulse P2a). The polarization reversal portion 144 includes a portion through which the second pulse P2a traveling along the optical path OP1 propagates and a portion through which the second pulse P2a traveling along the optical path OP2 propagates. In addition, although the polarization inversion part 144 is PPLN (periodically poled lithium niobate) in FIG. 2, it may be PPLT (lithium tantalate) or PPKTP, for example.

The polarization inverting portions 144, through which the second pulse P2a traveling along the optical path OP1 propagates, are arranged at a predetermined interval D1. The polarization inverting portions 144, through which the second pulse P2a traveling along the optical path OP2 propagates, are arranged at a predetermined interval D2. The predetermined interval differs for each traveling light. That is, the predetermined interval D1 is different from the predetermined interval D2.

A domain-inverted portion 144 is formed in the LN crystal substrate 142 . There is only one LN crystal substrate 142, and all of the polarization inversion parts 144 are formed thereon. In addition, in the first embodiment, the LN crystal substrate 142 may be a nonlinear optical crystal substrate instead of the LN crystal substrate. Similarly, in other embodiments, a nonlinear optical crystal substrate can be used instead of the LN crystal substrate.

A centroid 144c of the polarization inversion portion 144 through which the second pulse P2a traveling along the optical path OP1 propagates is arranged on a straight line parallel to the x-axis of the LN crystal substrate 142. FIG. A centroid 144c of the polarization inversion portion 144 through which the second pulse P2a traveling along the optical path OP2 propagates is also arranged on a straight line parallel to the x-axis of the LN crystal substrate 142. FIG. The centroid 144c of the polarization inversion portion 144 coincides with the center of gravity when it is assumed that the polarization inversion portion 144 is uniformly gravitational.

The mirror 15 receives the second pulse (after wavelength conversion) P2b that has traveled along the optical path OP2 and reflects it toward the dichroic mirror 16 .

A dichroic mirror (multiplexer) (DCM) 16 receives from the wavelength changing section 14 the second pulse (after wavelength conversion) P2b output from the wavelength changing section 14 that has traveled along the optical path OP1. Further, the dichroic mirror 16 receives from the mirror 15 the second pulse (after wavelength conversion) P2b output from the wavelength changing section 14 that has traveled along the optical path OP2. Further, the dichroic mirror 16 multiplexes the second pulse (after wavelength conversion) P2b output from the wavelength changing section 14 that has traveled along the optical path OP1 and the pulse that has traveled along the optical path OP2, and outputs a predetermined frequency ( 2 kHz), output a third pulse (before filtering) P3a.

However, in the output of the dichroic mirror 16, in addition to the third pulse (before filtering) P3a, the laser light (pump light) with wavelength W1 [nm] output from the excitation laser 10 and the red light generated by the wavelength changing section 14 are included. It is mixed with the idler light in the outer region. When laser light (pump light) is applied to the wavelength changing section 14, the signal light and the idler light are generated by optical parametric generation. The signal light is the output (second pulse (after wavelength conversion) P2b) of the wavelength changing section 14 (the same applies to the wavelength changing sections of other embodiments).

A filter (F) 17 removes the pump light and idler light from the third pulse (before filtering) P3a and outputs a third pulse (after filtering) P3b.

An optical fiber (MMF) 18 receives the third pulse P3a output from the dichroic mirror 16 via a filter 17 at one end and outputs it from the other end.

Next, operation of the first embodiment will be described.

First, the excitation laser 10 outputs laser light with a predetermined wavelength W1 [nm] as a first pulse P1 (see FIG. 3) with a predetermined frequency (for example, 2 kHz). The first pulse P1 is attenuated by the optical attenuator 11 and then applied to the acoustooptic modulator 12 . A timing control circuit 19 controls the output timing of the acoustooptic modulator 12 (see FIG. 3).

When the acoustooptic modulator 12 receives odd-numbered (1st, 3rd, 5th, . . . ) pulses of the first pulse P1, no acoustic wave is applied to the acoustooptic modulator 12 . As a result, the odd-numbered pulses of the first pulse P1 pass straight through the acousto-optic modulator 12 (optical path OP1). Therefore, the traveling light traveling along the optical path OP1 is a second pulse (before wavelength conversion) P2a having a frequency (1 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (two). Become.

When the acoustooptic modulator 12 receives the even-numbered (2nd, 4th, 6th, . As a result, even-numbered pulses of the second pulse P1 are transmitted through the acousto-optic modulator 12 while being diffracted to some extent (optical path OP2). Therefore, the traveling light traveling along the optical path OP2 is a second pulse (before wavelength conversion) P2a having a frequency (1 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (two). Become.

Moreover, the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling along the optical path OP1 differs from the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling the optical path OP2 by 180 degrees.

The traveling light traveling along the optical path OP1 (second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) propagates through the polarization inverting portions 144 arranged at a predetermined interval D1 in the wavelength changing portion 14, The wavelength is converted to W2 [nm] to become a second pulse (after wavelength conversion) P2b, which is applied to the dichroic mirror 16. FIG.

The traveling light traveling along the optical path OP2 (second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) propagates through the polarization inverting portions 144 arranged at a predetermined interval D2 in the wavelength changing portion 14, The wavelength is converted to W3 [nm] to become the second pulse (after wavelength conversion) P2b, which is reflected by the mirror 15 and given to the dichroic mirror 16. FIG.

Of the second pulse (after wavelength conversion) P2b output from the wavelength changing section 14, the wavelength W2 [nm] and the wavelength W3 [nm] are multiplexed by the dichroic mirror 16 to obtain a predetermined frequency (2 kHz). ), resulting in a third pulse (before filtering) P3a.

The filter 17 removes the pump light and the idler light from the third pulse (before filtering) P3a, resulting in a third pulse (after filtering) P3b. A third pulse (after filtering) P3b is applied to one end of the optical fiber 18 and output from the other end.

According to a first embodiment, the third pulse (after filtering) P3b can be output from the optical fiber 18 . The third pulse (after filtering) P3b is obtained by irradiating pulsed light with wavelength W2 [nm] and then immediately (for example, 500 microseconds) with another pulsed light with wavelength W3 [nm]. . That is, according to the first embodiment, it is possible to irradiate pulsed light of a certain wavelength and then immediately irradiate pulsed light of another wavelength.

In the first embodiment, the centroid 144c of the polarization inversion portion 144 is arranged on a straight line parallel to the x-axis of the LN crystal substrate 142 (see FIG. 2). The following modifications are conceivable for the arrangement of the core 144c.

FIG. 4 is a plan view of the wavelength changing section 14 according to the modification of the first embodiment. 4, unlike FIG. 1, in FIG. 4, the x-axis direction of the LN crystal substrate 142 is shown parallel to the lateral direction of the paper, unlike FIG.

Referring to FIG. 4, in the wavelength changing portion 14 according to the modification of the first embodiment, the polarization inverting portion 144 through which traveling light (the second pulse P2a traveling along the optical path OP1) propagates is arranged at a predetermined interval D1. , and the centroid 144c is arranged on a straight line (for example, on the traveling direction) parallel to the traveling direction of the traveling light (the second pulse P2a traveling along the optical path OP1). Further, the polarization reversal portions 144 through which the traveling light (the second pulse P2a traveling along the optical path OP2) propagates are arranged with a predetermined interval D2, and the centroid 144c thereof is the traveling light (the second pulse P2a traveling along the optical path OP2). They are arranged on a straight line parallel to the direction of travel of the pulse P2a) (for example, on the direction of travel).

According to the modified example of the first embodiment as described above, the vertical length (the length in the Y-axis direction) of the polarization inversion portion 144 can be made shorter than in the case of the first embodiment. can.

Further, in the first embodiment, the polarization inverting portion 144 is provided in the wavelength changing portion 14 (see FIGS. 2 and 4). Variants with nonlinear optical crystals are also conceivable. For example, the wavelength changing section 14 can be OPO (optical parametric oscillation), SHG (second harmonic generation) or THG (third harmonic generation) by BPM (birefringent phase matching).

Second Embodiment The laser light output device 1 according to the second embodiment is different from the first embodiment in which there is only one LN crystal substrate 142 in that an LN crystal substrate is provided for each traveling light that propagates. It is different from the laser light output device 1 according to the form.

FIG. 5 is a diagram showing the configuration of the laser light output device 1 according to the second embodiment. A laser light output device 1 according to the second embodiment includes an excitation laser (pulse laser output unit) 10, an optical attenuator (ATT) 11, an acousto-optic modulator (optical path determination unit) (AOM) 12, and a rhomboid prism 13. , wavelength changing units (PPLN) 14a, 14b, mirror 15, dichroic mirror (multiplexer) (DCM) 16, filter (F) 17, optical fiber (MMF) 18, timing control circuit (timing control unit) 19 . Hereinafter, parts similar to those of the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

Excitation laser (pulse laser output unit) 10, optical attenuator (ATT) 11, acousto-optic modulator (optical path determination unit) (AOM) 12, mirror 15, dichroic mirror (multiplexer) (DCM) 16, filter (F ) 17, an optical fiber (MMF) 18, and a timing control circuit (timing control section) 19 are the same as those in the first embodiment, and description thereof is omitted.

The rhomboid prism 13 receives the second pulse (before wavelength conversion) P2a that has traveled along the optical path OP2, and changes the optical path so as to be parallel and away from the optical path OP1.

The wavelength changing unit (PPLN) 14a receives the second pulse P2a (wavelength W1 [nm]) that has traveled along the optical path OP1 from the acousto-optic modulator 12, and converts it into a second pulse P2b (wavelength W2 [nm]). Convert. The configuration of the wavelength change portion 14a corresponds to the polarization inversion portions 144 arranged at a predetermined interval D1 and the LN crystal substrate 142 on which the polarization inversion portions 144 are formed in FIG. 2 or FIG.

The wavelength changing unit (PPLN) 14b receives from the rhomboid prism 13 the one (wavelength W1 [nm]) of the second pulse P2a that has traveled along the optical path OP2, and converts it into a second pulse P2b (wavelength W3 [nm]). do. The configuration of the wavelength change portion 14b corresponds to the polarization inversion portions 144 arranged at a predetermined interval D2 and the LN crystal substrate 142 on which the polarization inversion portions 144 are formed in FIG. 2 or FIG.

The LN crystal substrate of the wavelength changing portion 14a is different from the LN crystal substrate of the wavelength changing portion 14b. That is, the LN crystal substrate of the wavelength changing portion 14a and the LN crystal substrate of the wavelength changing portion 14b are provided for each propagating traveling light (one traveling along the optical path OP1 and one traveling along the optical path OP2). there is

The operation of the second embodiment is the same as that of the first embodiment, so the explanation is omitted.

According to the second embodiment, the LN crystal substrate is provided for each propagating traveling light (one traveling along the optical path OP1 and one traveling along the optical path OP2). Moreover, the manufacturing conditions for the polarization inversion portion 144 can be set, and the wavelength changing portions 14a and 14b can be easily manufactured.

Third Embodiment A laser light output device 1 according to a third embodiment has an acousto-optic modulator (AOM) (optical path determining section) 12 instead of an acousto-optical deflector (AOD) (optical path determining section) 120. It differs from the laser light output device 1 according to the first embodiment in that it is used.

FIG. 6 is a diagram showing the configuration of the laser light output device 1 according to the third embodiment. FIG. 7 is a timing chart of the first pulse P1, second pulse (before wavelength conversion) P2a, second pulse (after wavelength conversion) P2b, and third pulse (after filtering) P3b according to the third embodiment. In FIG. 7, the width of the line indicating the pulse and the type of line (solid line, dashed line or dashed line) are changed according to the wavelength.

The laser light output device 1 according to the third embodiment includes an excitation laser (pulse laser output unit) 10, an optical attenuator (ATT) 11, an acousto-optic deflector (AOD) (optical path determination unit) 120, a wavelength change unit ( PPLN) 14 , mirror 154 , dichroic mirrors (multiplexer) (DCM) 162 and 164 , filter (F) 17 , optical fiber (MMF) 18 and timing control circuit (timing control section) 19 . Hereinafter, parts similar to those of the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

An excitation laser (pulse laser output section) 10, an optical attenuator (ATT) 11, a filter (F) 17, an optical fiber (MMF) 18, and a timing control circuit (timing control section) 19 are the same as in the first embodiment. Yes, so the explanation is omitted. However, the timing control circuit 19 controls the output timing of the acoustooptic deflector 120 (see FIG. 7).

An acousto-optic deflector (AOD) (optical path determination unit) 120 receives the first pulse P1 and determines the optical path of each of the first pulses P1 to one of the plurality of optical paths OP1, OP2, and OP3. Output.

For example, referring to FIGS. 6 and 7, the acousto-optic deflector 120 receives the 1+3Nth (1st, 4th, 7th, . At this point, no acoustic waves are applied to the acousto-optic deflector 120 . Then, the 1+3Nth pulse of the first pulse P1 is transmitted straight through the acousto-optic deflector 120 (optical path OP1).

Also, when the acoustooptic deflector 120 receives the 2+3Nth (2nd, 5th, 8th, . Then, the 2+3Nth pulse of the first pulse P1 is transmitted through the acoustooptic deflector 120 while being diffracted to some extent (optical path OP2).

Further, when the acoustooptic deflector 120 receives the 3+3Nth (3rd, 6th, 9th, . is different from ω2). Then, the 3+3Nth pulse of the first pulse P1 is transmitted through the acoustooptic deflector 120 while being diffracted to some extent (optical path OP3). However, the angle that the optical path OP3 makes with the optical path OP1 (less than 90 degrees) is larger than the angle that the optical path OP2 makes with the optical path OP1 (however, less than 90 degrees).

When the acousto-optic deflector 120 receives the 1+3Nth pulse of the first pulse P1, the acousto-optic deflector 120 receives an acoustic wave (angular frequency ω1) (where ω1 is different from ω2 and ω3). may

Accordingly, the acousto-optic deflector 120 obtains a frequency (2/3 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of the plurality of optical paths (3) from each of the plurality of optical paths OP1, OP2, and OP3. ), and the second pulse (before wavelength conversion) P2a, which is a pulse with a phase difference of 120 degrees, is output.

A wavelength changing unit (PPLN) 14 receives traveling light (which is the second pulse P2a) traveling through each of the plurality of optical paths OP1, OP2, and OP3, changes the wavelength to a different wavelength, and outputs the light. The output of the wavelength changing section 14 is the second pulse (after wavelength conversion) P2b.

Referring to FIG. 7, wavelength changing unit 14 receives the second pulse P2a that has traveled along optical path OP1 (wavelength W1 [nm]) and converts it into a second pulse P2b (wavelength W2 [nm]). . Further, the wavelength changing unit 14 receives the second pulse P2a (wavelength W1 [nm]) that has traveled through the optical path OP2 and converts it into a second pulse P2b (wavelength W3 [nm]). Furthermore, the wavelength changing unit 14 receives the second pulse P2a (wavelength W1 [nm]) that has traveled through the optical path OP3 and converts it into a second pulse P2b (wavelength W4 [nm]).

The configuration of the wavelength changing section 14 is the same as in the first embodiment and its modification (see FIGS. 2 and 4). However, the polarization inversion portion 144, in which the second pulse P2a propagated through the optical path OP3, is arranged at a predetermined interval D3 (D3 is different from D1 and D2).

The mirror 154 receives the second pulse (after wavelength conversion) P2b that has traveled along the optical path OP3 and reflects it toward the dichroic mirror 162 .

A dichroic mirror (multiplexer) (DCM) 162 separates the second pulse (after wavelength conversion) P2b that has traveled along the optical path OP2 and the reflected light from the mirror 154 (second pulse (after wavelength conversion) P2b). Among them, the light traveling along the optical path OP3) is combined and reflected toward the dichroic mirror 164 .

A dichroic mirror (multiplexer) (DCM) 164 combines the second pulse (after wavelength conversion) P2b that has traveled along the optical path OP1 with the light from the dichroic mirror 162 (second pulse (after wavelength conversion) P2b). Among them, the one that has traveled through the optical path OP2 and the one that has traveled through the optical path OP3 are multiplexed, and a third pulse (before filtering) P3a having a predetermined frequency (2 kHz) is output.

Next, the operation of the third embodiment will be explained.

First, the excitation laser 10 outputs laser light with a predetermined wavelength W1 [nm] as a first pulse P1 (see FIG. 7) with a predetermined frequency (for example, 2 kHz). The first pulse P1 is attenuated by the optical attenuator 11 and then applied to the acousto-optic deflector 120 . A timing control circuit 19 controls the output timing of the acousto-optic deflector 120 (see FIG. 7).

When the acoustooptic deflector 120 receives the 1+3Nth (1st, 4th, 7th, . . . ) pulses of the first pulse P1, no acoustic wave is applied to the acoustooptic deflector 120 . As a result, the 1+3N-th pulse of the first pulse P1 is directly transmitted through the acousto-optic deflector 120 (optical path OP1). Therefore, the traveling light traveling along the optical path OP1 is a second pulse (before wavelength conversion) having a frequency (2/3 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (3). becomes P2a.

When the acoustooptic deflector 120 receives the 2+3Nth (2nd, 5th, 8th, . As a result, the 2+3N-th pulse of the second pulse P1 is transmitted through the acousto-optic deflector 120 while being diffracted to some extent (optical path OP2). Therefore, the traveling light traveling along the optical path OP2 is a second pulse (before wavelength conversion) having a frequency (2/3 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (3). becomes P2a.

When the acoustooptic deflector 120 receives the 3+3Nth (3rd, 6th, 9th, . As a result, the 3+3Nth pulse of the second pulse P1 is transmitted through the acoustooptic deflector 120 while being diffracted to some extent (optical path OP3). Therefore, the traveling light traveling along the optical path OP3 is a second pulse (before wavelength conversion) having a frequency (2/3 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (3). becomes P2a.

Moreover, the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling along the optical path OP1 differs from the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling the optical path OP2 by 120 degrees. The phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling along the optical path OP2 differs by 120 degrees from the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling the optical path OP3. The phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling along the optical path OP1 differs from the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling the optical path OP3 by 240 degrees.

The traveling light traveling along the optical path OP1 (second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) propagates through the polarization inverting portions 144 arranged at a predetermined interval D1 in the wavelength changing portion 14, The wavelength is converted to W2 [nm] to become the second pulse (after wavelength conversion) P2b, which is given to the dichroic mirror 164. FIG.

The traveling light traveling along the optical path OP2 (second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) propagates through the polarization inverting portions 144 arranged at a predetermined interval D2 in the wavelength changing portion 14, The wavelength is converted to W3 [nm] to become the second pulse (after wavelength conversion) P2b, which is reflected by the dichroic mirror 162 and given to the dichroic mirror 164. FIG.

The traveling light traveling along the optical path OP3 (second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) propagates through the polarization inverting portions 144 arranged at a predetermined interval D2 in the wavelength changing portion 14, The wavelength is converted to W4 [nm] to become the second pulse (after wavelength conversion) P2b, which is reflected by the mirror 154 and given to the dichroic mirror 164 via the dichroic mirror 162 .

Of the second pulse (after wavelength conversion) P2b output from the wavelength changing unit 14, the wavelength W2 [nm], the wavelength W3 [nm], and the wavelength W4 [nm] are divided by the dichroic mirror 164. After being multiplexed, a third pulse (before filtering) P3a having a predetermined frequency (2 kHz) is obtained.

The filter 17 removes the pump light and the idler light from the third pulse (before filtering) P3a, resulting in a third pulse (after filtering) P3b. A third pulse (after filtering) P3b is applied to one end of the optical fiber 18 and output from the other end.

According to the third embodiment, since the acousto-optic deflector 120 is used instead of the acousto-optic modulator 12, the number of optical paths can be increased to three (optical paths OP1, OP2, OP3). As a result, the third pulse (after filtering) P3b is irradiated with pulsed light with a wavelength of W2 [nm], and immediately (for example, 500 microseconds) is irradiated with another pulsed light with a wavelength of W3 [nm]. . Moreover, immediately (for example, 500 microseconds) after being irradiated with the pulsed light of wavelength W3 [nm], another pulsed light of wavelength W4 [nm] is further irradiated. That is, according to the third embodiment, it is possible to irradiate pulsed light of a certain wavelength, immediately irradiate pulsed light of another wavelength, and then immediately irradiate pulsed light of another wavelength. Thus, according to the third embodiment, it is possible to irradiate pulsed light with three wavelengths.

Although the number of optical paths is three in the third embodiment, the number may be four or more. This makes it possible to irradiate pulsed light with four or more wavelengths.

Further, in the third embodiment, as in the first embodiment, there is only one LN crystal substrate 142, and all the polarization inversion parts 144 are formed. However, as in the second embodiment, an LN crystal substrate may be provided for each propagating traveling light (one traveling along the optical path OP1, one traveling along the optical path OP2, and one traveling along the optical path OP3). .

Fourth Embodiment In the laser light output device 1 according to the fourth embodiment, instead of the acousto-optic deflector (AOD) (optical path determining unit) 120, the optical path determining unit (first acousto-optic modulator (AOM) 12a and a second acousto-optic modulator (AOM) 12b).

FIG. 8 is a diagram showing the configuration of the laser light output device 1 according to the fourth embodiment. FIG. 9 is an enlarged view of the vicinity of the optical path determining section (the first acousto-optic modulator (AOM) 12a and the second acousto-optic modulator (AOM) 12b) in the laser light output device 1 according to the fourth embodiment. .

A laser light output device 1 according to the fourth embodiment includes an excitation laser (pulse laser output unit) 10, optical attenuators (ATT) 11a, 11b, 11c, a first acousto-optic modulator (AOM) 12a, a second acoustic Optical modulator (AOM) 12b, rhomboid prisms 13a, 13b, wavelength changing units (PPLN) 14a, 14b, 14c, mirror 154, dichroic mirrors (multiplexer) (DCM) 162, 164, filter (F) 172, 174 , 176 , an optical fiber (MMF) 18 , a timing control circuit (timing control section) 19 and a lens (L) 192 . Hereinafter, parts similar to those of the third embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

The excitation laser (pulse laser output section) 10, mirror 154, dichroic mirror (multiplexer) (DCM) 162, 164, optical fiber (MMF) 18, and timing control circuit (timing control section) 19 are the third embodiment. , and the description thereof is omitted. However, the optical fiber (MMF) 18 receives the third pulse P3 output from the dichroic mirror 164 at one end via the lens (L) 192 and outputs it from the other end. The timing control circuit 19 also controls the output timing (see P2a in FIG. 7) of the optical path determining section (first acousto-optic modulator (AOM) 12a and second acousto-optic modulator (AOM) 12b).

The optical path determining section has a first acousto-optic modulator (AOM) 12a and a second acousto-optic modulator (AOM) 12b. Both the planar shapes of the first acousto-optic modulator (AOM) 12a and the second acousto-optic modulator (AOM) 12b are rectangular.

The long side of the first acousto-optic modulator (AOM) 12a receives the first pulse P1. The short side of the first acousto-optic modulator (AOM) 12a is tilted counterclockwise by θB (Bragg angle) with respect to the optical path OP2.

The longer side of the second acousto-optic modulator (AOM) 12b receives the output of the first acousto-optic modulator 12a. The shorter side of the second acousto-optic modulator (AOM) 12b is tilted clockwise by θB (Bragg angle) with respect to the optical path OP2.

A first acousto-optic modulator (AOM) 12a receives the first pulse P1, determines the optical path of each of the first pulses P1 to one of a plurality of optical paths OP1 and OP2, and outputs the optical path. In the fourth embodiment, the first acousto-optic modulator (AOM) 12a diffracts (optical path OP1) or straightens (optical path OP2) each of the first pulses P1 and outputs them.

A second acousto-optic modulator (AOM) 12b receives the output of the first acousto-optic modulator 12a and modulates one or more optical paths OP1, OP2, OP3 for each pulse of the output of the first acousto-optic modulator 12a. An optical path is determined and output to one of them. In the fourth embodiment, the second acousto-optic modulator (AOM) 12b receives the first pulse that has traveled straight (optical path OP2), diffracts it (optical path OP3) or straightens it (optical path OP2) and outputs it, The diffracted first pulse (optical path OP1) is received and output after straight travel (optical path OP1).

Note that the first pulse P1, the second pulse (before wavelength conversion) P2a, the second pulse (after wavelength conversion) P2b, and the third pulse P3 (input to the optical fiber (MMF) 18) according to the fourth embodiment The timing chart is similar to that of FIG. 7 (however, P3b in FIG. 7 shall be read as P3).

For example, referring to FIGS. 9 and 7, when the optical path determination unit receives the 1+3Nth (1st, 4th, 7th, . , provides an acoustic wave to the first acousto-optic modulator (AOM) 12a and no acoustic wave to the second acousto-optic modulator (AOM) 12b. Then, the 1+3Nth pulse of the first pulse P1 travels along the optical path OP1 (see FIG. 9).

Further, when the optical path determination unit receives the 2+3Nth (2nd, 5th, 8th, . (AOM) 12b is also not given an acoustic wave. Then, the 2+3Nth pulse of the first pulse P1 travels along the optical path OP2 (see FIG. 9).

Further, when the optical path determination unit receives the 3+3Nth (3rd, 6th, 9th, . Acoustic waves are applied to a two-acousto-optic modulator (AOM) 12b. Then, the 3+3Nth pulse of the first pulse P1 travels along the optical path OP3 (see FIG. 9).

As a result, the optical path determination unit divides a predetermined frequency (for example, 2 kHz) by the number of the plurality of optical paths (3) to obtain a frequency (2/3 kHz) from each of the plurality of optical paths OP1, OP2, and OP3. and output a second pulse (before wavelength conversion) P2a, which is a pulse with a phase difference of 120 degrees.

The rhomboid prism 13a receives the second pulse (before wavelength conversion) P2a that has traveled along the optical path OP1, and changes the optical path so as to be parallel and away from the optical path OP1. The rhomboid prism 13b receives the second pulse (before wavelength conversion) P2a that has traveled along the optical path OP3, and changes the optical path so as to be parallel and away from the optical path OP3.

Optical attenuators (ATT) 11a, 11b, and 11c convert light traveling along the optical path OP1 (output of the rhomboid prism 13a), light traveling along the optical path OP2, and light traveling along the optical path OP3 (output of the rhomboid prism 13b). It is attenuated and supplied to the wavelength changing units (PPLN) 14a, 14b and 14c.

The wavelength changing units (PPLN) 14a and 14b are the same as those in the second embodiment, and description thereof is omitted. A wavelength changing unit (PPLN) 14c receives from the rhomboid prism 13b the second pulse P2a that has traveled along the optical path OP3 (wavelength W1 [nm]) and converts it into a second pulse P2b (wavelength W4 [nm]). do. 2 or 4, the wavelength changing portion 14b is composed of polarization inverting portions 144 arranged at a predetermined interval D2 (the predetermined interval D2 is changed to D3) and It corresponds to the LN crystal substrate 142 that has

The LN crystal substrate of the wavelength changing portion 14a, the LN crystal substrate of the wavelength changing portion 14b, and the LN crystal substrate of the wavelength changing portion 14c are different. That is, the LN crystal substrate of the wavelength changing portion 14a, the LN crystal substrate of the wavelength changing portion 14b, and the LN crystal substrate of the wavelength changing portion 14c are separated from each other by the propagating traveling light (the light traveling along the optical path OP1 and the light traveling along the optical path OP1). are provided for each optical path OP2 and optical path OP3.

Filters (F) 172, 174, 176 remove pump light and idler light from the output of wavelength changing units (PPLN) 14a, 14b, 14c, and dichroic mirrors (multiplexers) (DCM) 164, 162, Output to mirror 154 .

A lens (L) 192 receives the output of the dichroic mirror (multiplexer) (DCM) 164 and provides it to the optical fiber (MMF) 18 .

Next, operation of the fourth embodiment will be described.

First, the excitation laser 10 outputs laser light with a predetermined wavelength W1 [nm] as a first pulse P1 (see FIG. 7) with a predetermined frequency (for example, 2 kHz). A first pulse P1 is applied to a first acousto-optic modulator (AOM) 12a of the optical path determining section. The timing control circuit 19 controls the output timing of the optical path determining section (see P2a in FIG. 7).

When the optical path determination unit receives the 1+3Nth (1st, 4th, 7th, . An acoustic wave is applied and no acoustic wave is applied to the second acousto-optic modulator (AOM) 12b. Then, the 1+3Nth pulse of the first pulse P1 travels along the optical path OP1 (see FIG. 9). Therefore, the traveling light traveling along the optical path OP1 is a second pulse (before wavelength conversion) having a frequency (2/3 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (3). P2a (see FIG. 7).

When the optical path determination unit receives the 2+3Nth (2nd, 5th, 8th, . ) 12b is not given an acoustic wave either. Then, the 2+3Nth pulse of the first pulse P1 travels along the optical path OP2 (see FIG. 9). Therefore, the traveling light traveling along the optical path OP2 is a second pulse (before wavelength conversion) having a frequency (2/3 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (3). P2a (see FIG. 7).

When the optical path determination unit receives the 3+3Nth (3rd, 6th, 9th, . Acoustic waves are applied to an optical modulator (AOM) 12b. Then, the 3+3Nth pulse of the first pulse P1 travels along the optical path OP3 (see FIG. 9). Therefore, the traveling light traveling along the optical path OP3 is a second pulse (before wavelength conversion) having a frequency (2/3 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (3). P2a (see FIG. 7).

Moreover, the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling along the optical path OP1 differs from the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling the optical path OP2 by 120 degrees. The phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling along the optical path OP2 differs by 120 degrees from the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling the optical path OP3. The phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling along the optical path OP1 differs from the phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling the optical path OP3 by 240 degrees.

The traveling light traveling along the optical path OP1 (the second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) is changed in its optical path by the rhomboid prism 13a and is attenuated by the optical attenuator (ATT) 11a so that the wavelength It is given to the changing unit (PPLN) 14a. Furthermore, the light given to the wavelength changing section (PPLN) 14a propagates through the polarization inverting sections 144 arranged at a predetermined interval D1 in the wavelength changing section 14a, and the wavelength is converted to W2 [nm], The second pulse (after wavelength conversion) becomes P2b, and the pump light and idler light are removed by the filter (F) 172, and then applied to the dichroic mirror 164. FIG.

The traveling light traveling along the optical path OP2 (second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) is attenuated by the optical attenuator (ATT) 11b and applied to the wavelength changing section (PPLN) 14b. Furthermore, the light given to the wavelength changing section (PPLN) 14b propagates through the polarization inverting sections 144 arranged at a predetermined interval D2 in the wavelength changing section 14b, and the wavelength is converted to W3 [nm], The second pulse (after wavelength conversion) becomes P2b, the pump light and the idler light are removed by the filter (F) 174, reflected by the dichroic mirror 162, and then given to the dichroic mirror 164. FIG.

The traveling light traveling along the optical path OP3 (the second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) is changed in its optical path by the rhomboid prism 13b and attenuated by the optical attenuator (ATT) 11c so that the wavelength It is provided to the changing unit (PPLN) 14c. Furthermore, the light given to the wavelength changing portion (PPLN) 14c propagates through the polarization inverting portions 144 arranged at a predetermined interval D3 in the wavelength changing portion 14a, and the wavelength is converted to W4 [nm]. The second pulse (after wavelength conversion) becomes P2b, and the filter (F) 176 removes the pump light and idler light.

Among the second pulses (after wavelength conversion) P2b output from the wavelength changing units 14a, 14b, and 14c, those with a wavelength of W2 [nm], those with a wavelength of W3 [nm], and those with a wavelength of W4 [nm] are The signals are combined by the dichroic mirror 164 to become the third pulse P3 having a predetermined frequency (2 kHz).

The third pulse P3 passes through the lens (L) 192 and is given to the optical fiber (MMF) 18. FIG.

According to the fourth embodiment, instead of the acousto-optic deflector 120 in the third embodiment, two acousto-optic modulators (first acousto-optic modulator (AOM) 12a and second acousto-optic modulator ( By using the AOM) 12b), it is possible to irradiate pulsed light of three wavelengths as in the third embodiment. Acousto-optic modulators (two pieces) are easier to mount on the laser light output device 1 than acousto-optic deflectors, and have the advantage of low cost.

Further, in the fourth embodiment, as in the third embodiment, only one LN crystal substrate 142 may be provided, and all of the polarization inversion parts 144 may be formed.

In addition, in the fourth embodiment, the following modifications are conceivable for the operation of the optical path determining section (the first acousto-optic modulator (AOM) 12a and the second acousto-optic modulator (AOM) 12b).

FIG. 12 is an enlarged view of the vicinity of the optical path determination unit (the first acousto-optic modulator (AOM) 12a and the second acousto-optic modulator (AOM) 12b) in the laser light output device 1 according to the modification of the fourth embodiment. It is a diagram.

A first acousto-optic modulator (AOM) 12a receives the first pulse P1, determines the optical path of each of the first pulses P1 to one of a plurality of optical paths OP1 and OP2, and outputs the optical path. For example, the first acousto-optic modulator (AOM) 12a diffracts (optical path OP1) or straightens (optical path OP2) each of the first pulses P1 and outputs them. Up to this point, it is the same as the fourth embodiment.

Here, a second acousto-optic modulator (AOM) 12b receives the output of the first acousto-optic modulator 12a and provides one or more optical paths OP1, OP2 for each pulse of the output of the first acousto-optic modulator 12a. , OP3 and output. In the modified example of the fourth embodiment, the second acousto-optic modulator (AOM) 12b receives the first pulse that has traveled straight (optical path OP2) and causes it to travel straight (optical path OP2) (the point that does not diffract is the fourth ), the diffracted first pulse (optical path OP1) is received and diffracted (optical path OP3) or propagated straight (optical path OP1) (different from the fourth embodiment in that it may be diffracted) Output.

The shorter side of the second acousto-optic modulator (AOM) 12b is inclined counterclockwise by θB (Bragg angle) with respect to the optical path OP1.

Fifth Embodiment The laser light output device 1 according to the fifth embodiment includes two acousto-optic modulators (a first acousto-optic modulator (AOM) 12a and a second acousto-optic modulator (AOM) 12a) as in the fourth embodiment. The main difference from the laser light output device 1 according to the fourth embodiment is that pulsed light beams of four different wavelengths are emitted while using an AOM (AOM) 12b).

FIG. 10 is a diagram showing the configuration of the laser light output device 1 according to the fifth embodiment. FIG. 11 is an enlarged view of the vicinity of the optical path determining section (the first acousto-optic modulator (AOM) 12a and the second acousto-optic modulator (AOM) 12b) in the laser light output device 1 according to the fifth embodiment. .

A laser light output device 1 according to the fifth embodiment includes an excitation laser (pulse laser output unit) 10, optical attenuators (ATT) 11a, 11b, 11c, and 11d, a first acoustooptic modulator (AOM) 12a, a second acousto-optic modulator (AOM) 12b, rhomboid prisms 13c, 13d, 13e, 13f, wavelength changing units (PPLN) 14a, 14b, 14c, 14d, mirror 154, dichroic mirror (multiplexer) (DCM) 161, 162 , 164 , filters (F) 172 , 174 , 176 , 178 , optical fiber (MMF) 18 , timing control circuit (timing control section) 19 , and lens (L) 192 . Hereinafter, the same reference numerals are assigned to the same parts as in the fourth embodiment, and the description thereof will be omitted.

Pump laser (pulse laser output unit) 10, optical attenuators (ATT) 11a, 11b, 11c, wavelength change units (PPLN) 14a, 14b, 14c, mirror 154, dichroic mirror (multiplexer) (DCM) 162, 164 , filters (F) 172, 174, 176, an optical fiber (MMF) 18, a timing control circuit (timing control section) 19, and a lens (L) 192 are the same as those in the fourth embodiment, and descriptions thereof are omitted.

However, the mirror 154 receives the second pulse (after wavelength conversion) P2b that has traveled along the optical path OP4 and reflects it toward the dichroic mirror 161 . A dichroic mirror (multiplexer) (DCM) 162 multiplexes the second pulse (after wavelength conversion) P2b, which has traveled along the optical path OP2, with the reflected light from the dichroic mirror 161. reflect towards. A filter (F) 176 removes pump light and idler light from the output of the wavelength changer (PPLN) 14 c and outputs the result to a dichroic mirror (multiplexer) (DCM) 161 .

A filter (F) 178 removes pump light and idler light from the output of the wavelength changer (PPLN) 14 d and outputs the output to the mirror 154 .

The optical path determining section has a first acousto-optic modulator (AOM) 12a and a second acousto-optic modulator (AOM) 12b. Both the planar shapes of the first acousto-optic modulator (AOM) 12a and the second acousto-optic modulator (AOM) 12b are rectangular.

The longer side of the first acousto-optic modulator (AOM) 12a and the longer side of the second acousto-optic modulator (AOM) 12b are parallel to each other. The optical path OP4 is inclined clockwise by θB (Bragg angle) with respect to the short side of the first acousto-optic modulator (AOM) 12a. The long side of the first acousto-optic modulator (AOM) 12a receives the first pulse P1, and the long side of the second acousto-optic modulator (AOM) 12b receives the output of the first acousto-optic modulator 12a. .

A first acousto-optic modulator (AOM) 12a receives the first pulse P1, determines the optical path of each of the first pulses P1 to one of the plurality of optical paths OP1 and OP4, and outputs the optical path. In the fifth embodiment, the first acousto-optic modulator (AOM) 12a diffracts (optical path OP1) or straightens (optical path OP4) each of the first pulses P1 and outputs them.

A second acousto-optic modulator (AOM) 12b receives the output of the first acousto-optic modulator 12a and for each pulse of the output of the first acousto-optic modulator 12a, one or more optical paths OP1, OP2, OP3, The optical path is determined and output to one of OP4. In the fifth embodiment, the second acousto-optic modulator (AOM) 12b diffracts (optical paths OP2, OP3) or rectilinearly (optical path OP1, OP4) and output. More specifically, the second acousto-optic modulator (AOM) 12b receives the first pulse straight (optical path OP4), diffracts it (optical path OP2) or straight (optical path OP4), and outputs the first pulse receives the diffracted light (optical path OP1), diffracts it (optical path OP3) or advances it straight (optical path OP1), and outputs it.

When the optical path determination unit receives the 1+4Nth (1st, 5th, 9th, . An acoustic wave is applied and no acoustic wave is applied to the second acousto-optic modulator (AOM) 12b. Then, the 1+4Nth pulse of the first pulse P1 travels along the optical path OP1 (see FIG. 11).

Further, when the optical path determination unit receives the 2+4Nth (2nd, 6th, 10th, . An acoustic wave is applied to an acousto-optic modulator (AOM) 12b. Then, the 2+4Nth pulse of the first pulse P1 travels along the optical path OP2 (see FIG. 11).

Further, when the optical path determination unit receives the 3+4Nth (3rd, 7th, 11th, . An acoustic wave is also applied to the optical modulator (AOM) 12b. Then, the 3+4Nth pulse of the first pulse P1 travels along the optical path OP3 (see FIG. 11).

Further, when the optical path determination unit receives the 4+4Nth (4th, 8th, 12th, . No acoustic wave is applied to the acousto-optic modulator (AOM) 12b either. Then, the 4+4Nth pulse of the first pulse P1 travels along the optical path OP4 (see FIG. 11).

As a result, the optical path determination unit selects a frequency (1/2 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of the plurality of optical paths (4) from each of the plurality of optical paths OP1, OP2, OP3, and OP4. ), and outputs a second pulse (before wavelength conversion) P2a, which is a pulse with a phase difference of 90 degrees.

The rhomboid prism 13c receives the second pulse (before wavelength conversion) P2a that has traveled along the optical path OP1, and changes the optical path so as to be parallel and away from the optical path OP1. The rhomboid prism 13e receives the second pulse (before wavelength conversion) P2a that has traveled along the optical path OP2, and changes the optical path so as to be parallel and away from the optical path OP2. The rhomboid prism 13f receives the second pulse (before wavelength conversion) P2a that has traveled along the optical path OP3, and changes the optical path so as to be parallel and away from the optical path OP3. The rhomboid prism 13d receives the second pulse (before wavelength conversion) P2a that has traveled along the optical path OP4, and changes the optical path so as to be parallel and away from the optical path OP4.

The optical attenuator (ATT) 11d attenuates the light (the output of the rhomboid prism 13d) traveling along the optical path OP4, and supplies the light to the wavelength changing section (PPLN) 14d.

A wavelength changing unit (PPLN) 14d receives from the rhomboid prism 13d the second pulse P2a that has traveled along the optical path OP4 (wavelength W1 [nm]) and converts it into a second pulse P2b (wavelength W5 [nm]). do. 2 or 4, the wavelength changing portion 14b is arranged at a predetermined interval D2 (however, the predetermined interval D2 is changed to D4, which is different from D1, D2, and D3). It corresponds to the domain inversion part 144 and the LN crystal substrate 142 on which it is formed.

The LN crystal substrate of the wavelength changing portion 14a, the LN crystal substrate of the wavelength changing portion 14b, the LN crystal substrate of the wavelength changing portion 14c, and the LN crystal substrate of the wavelength changing portion 14d are different. be. In other words, the LN crystal substrate of the wavelength changing portion 14a, the LN crystal substrate of the wavelength changing portion 14b, the LN crystal substrate of the wavelength changing portion 14c, and the LN crystal substrate of the wavelength changing portion 14d have a propagating progress. It is provided for each light (one that has traveled the optical path OP1, one that has traveled the optical path OP2, one that has traveled the optical path OP3, and one that has traveled the optical path OP4).

Next, the operation of the fifth embodiment will be explained.

First, the excitation laser 10 outputs laser light with a predetermined wavelength W1 [nm] as a first pulse P1 with a predetermined frequency (for example, 2 kHz). A first pulse P1 is applied to a first acousto-optic modulator (AOM) 12a of the optical path determining section. A timing control circuit 19 controls the output timing of the optical path determining section.

When the optical path determination unit receives the 1+4Nth (1st, 5th, 9th, . An acoustic wave is applied and no acoustic wave is applied to the second acousto-optic modulator (AOM) 12b. Then, the 1+4Nth pulse of the first pulse P1 travels along the optical path OP1 (see FIG. 11). Therefore, the traveling light traveling along the optical path OP1 is a second pulse (before wavelength conversion) having a frequency (1/2 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (4). becomes P2a.

When the optical path determination unit receives the 2+4Nth (2nd, 6th, 10th, . An acoustic wave is applied to the modulator (AOM) 12b. Then, the 2+4Nth pulse of the first pulse P1 travels along the optical path OP2 (see FIG. 11). Therefore, the traveling light traveling along the optical path OP2 is a second pulse (before wavelength conversion) having a frequency (1/2 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (4). becomes P2a.

When the optical path determination unit receives the 3+4Nth (3rd, 7th, 11th, . Acoustic waves are also applied to the device (AOM) 12b. Then, the 3+4Nth pulse of the first pulse P1 travels along the optical path OP3 (see FIG. 11). Therefore, the traveling light traveling along the optical path OP3 is a second pulse (before wavelength conversion) having a frequency (1/2 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (4). becomes P2a.

When the optical path determination unit receives the 4+4Nth (4th, 8th, 12th, . Acoustic waves are also not applied to the optical modulator (AOM) 12b. Then, the 4+4Nth pulse of the first pulse P1 travels along the optical path OP4 (see FIG. 11). Therefore, the traveling light traveling along the optical path OP4 is a second pulse (before wavelength conversion) having a frequency (1/2 kHz) obtained by dividing a predetermined frequency (for example, 2 kHz) by the number of a plurality of optical paths (4). becomes P2a.

Moreover, the phase of the traveling light (second pulse (before wavelength conversion) P2a) traveling along the optical path OP1, the phase of the traveling light (second pulse (before wavelength conversion) P2a) traveling along the optical path OP2, and the phase of the traveling light (second pulse (before wavelength conversion) P2a) traveling along the optical path OP3 The phase of the traveling light (the second pulse (before wavelength conversion) P2a) traveling through the optical path OP4 differs by 90 degrees from the phase of the traveling light (the second pulse (before the wavelength conversion) P2a) traveling through the optical path OP4.

The traveling light traveling along the optical path OP1 (the second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) is changed in its optical path by the rhomboid prism 13c and attenuated by the optical attenuator (ATT) 11a so that the wavelength It is given to the changing unit (PPLN) 14a. Furthermore, the light given to the wavelength changing section (PPLN) 14a propagates through the polarization inverting sections 144 arranged at a predetermined interval D1 in the wavelength changing section 14a, and the wavelength is converted to W2 [nm], The second pulse (after wavelength conversion) becomes P2b, and the pump light and idler light are removed by the filter (F) 172, and then applied to the dichroic mirror 164. FIG.

The traveling light traveling along the optical path OP2 (the second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) is changed in its optical path by the rhomboid prism 13e and is attenuated by the optical attenuator (ATT) 11b so that the wavelength It is given to the changing unit (PPLN) 14b. Furthermore, the light given to the wavelength changing section (PPLN) 14b propagates through the polarization inverting sections 144 arranged at a predetermined interval D2 in the wavelength changing section 14b, and the wavelength is converted to W3 [nm], The second pulse (after wavelength conversion) becomes P2b, the pump light and the idler light are removed by the filter (F) 174, reflected by the dichroic mirror 162, and then given to the dichroic mirror 164. FIG.

The traveling light traveling along the optical path OP3 (the second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) is changed in its optical path by the rhomboid prism 13f and attenuated by the optical attenuator (ATT) 11c so that the wavelength It is provided to the changing unit (PPLN) 14c. Furthermore, the light given to the wavelength changing portion (PPLN) 14c propagates through the polarization inverting portions 144 arranged at a predetermined interval D3 in the wavelength changing portion 14c, and the wavelength is converted to W4 [nm]. The second pulse (after wavelength conversion) becomes P2b, the pump light and idler light are removed by the filter (F) 176, reflected by the dichroic mirror 161, and applied to the dichroic mirror 164 via the dichroic mirror 162.

The traveling light traveling along the optical path OP4 (the second pulse (before wavelength conversion) P2a: wavelength W1 [nm]) is changed in its optical path by the rhomboid prism 13d and is attenuated by the optical attenuator (ATT) 11d so that the wavelength It is given to the changing unit (PPLN) 14d. Furthermore, the light given to the wavelength changing portion (PPLN) 14d propagates through the polarization inverting portions 144 arranged at a predetermined interval D4 in the wavelength changing portion 14d, and the wavelength is converted to W5 [nm], The second pulse (after wavelength conversion) becomes P2b, and the filter (F) 178 removes the pump light and idler light.

Of the second pulses (after wavelength conversion) P2b output from the wavelength changing units 14a, 14b, 14c, and 14d, those with a wavelength of W2 [nm], those with a wavelength of W3 [nm], and those with a wavelength of W4 [nm] and the wavelength W5 [nm] are combined by the dichroic mirror 164 to form a third pulse P3 having a predetermined frequency (2 kHz).

The third pulse P3 passes through the lens (L) 192 and is given to the optical fiber (MMF) 18. FIG.

According to the fifth embodiment, as in the fourth embodiment, while using two acousto-optic modulators (first acousto-optic modulator (AOM) 12a and second acousto-optic modulator (AOM) 12b) , it is possible to irradiate pulsed light of four different wavelengths, which is more than in the fourth embodiment.

Further, in the fifth embodiment, as in the third embodiment, only one LN crystal substrate 142 may be provided, and all the polarization inversion parts 144 may be formed.

Sixth Embodiment The sixth embodiment is a photoacoustic wave measuring device using the laser light output device 1 according to the first, second, third, fourth and fifth embodiments (including modifications). 100.

FIG. 13 is a functional block diagram showing the configuration of a photoacoustic wave measurement device 100 according to the sixth embodiment of the invention.

The photoacoustic wave measurement apparatus 100 according to the sixth embodiment is for measuring a measurement target 200 (for example, but not limited to, new blood vessels near basal cell carcinoma up to a depth of about 3 mm in the human body). , which includes a laser light output device 1 and a measurement unit 4 .

The laser light output device 1 is the same as the laser light output device 1 according to the first, second, third, fourth and fifth embodiments (including modifications). However, the laser light PL output from the laser light output device 1 is such that the third pulse (after filtering) P3b in the first, second, third, fourth and fifth embodiments (including modifications) is the optical fiber It has passed 18. Note that the laser light output device 1 provides the measurement unit 4 with a trigger signal synchronized with the time when the pulse in the laser light PL is output.

The measurement unit 4 measures the measurement object 200 based on the photoacoustic wave AW generated in the measurement object 200 by the laser beam PL. Note that the measurement unit 4 performs measurement in synchronization with the trigger signal given from the laser light output device 1 .

Next, the operation of the sixth embodiment will be explained.

A laser light output device 1 outputs a laser light PL. The laser light PL is similar to the third pulse (after filtering) P3b.

Laser light PL is applied to measurement target 200 . A photoacoustic wave AW is generated by applying the laser beam PL to the object 200 to be measured.

The measurement target 200 is measured by the measurement unit 4 based on the photoacoustic wave AW.

According to the sixth embodiment, photoacoustic wave measurement of the measurement target 200 can be performed by applying the laser light PL to the measurement target 200 . Moreover, irradiating the measurement object 200 with pulsed light of a certain wavelength and then immediately irradiating it with pulsed light of another wavelength is the same as in the first, second, third, fourth and fifth embodiments. It is possible as well.

Seventh Embodiment In the seventh embodiment, the laser light output device 1 and the ultrasonic pulse output section 2 according to the first, second, third, fourth and fifth embodiments (including modifications) are It relates to the photoacoustic wave measurement device 100 used.

FIG. 14 is a functional block diagram showing the configuration of a photoacoustic wave measurement device 100 according to the seventh embodiment of the invention.

The photoacoustic wave measurement device 100 according to the seventh embodiment is for measuring a measurement target 200 (for example, but not limited to, new blood vessels near basal cell carcinoma up to a depth of about 3 mm in the human body). and includes a laser light output device 1 , an ultrasonic pulse output section 2 and a measurement section 4 .

The laser light output device 1 is the same as the laser light output device 1 according to the first, second, third, fourth and fifth embodiments (including modifications). However, the laser light PL output from the laser light output device 1 is such that the third pulse (after filtering) P3b in the first, second, third, fourth and fifth embodiments (including modifications) is the optical fiber It has passed 18. Note that the laser light output device 1 provides the measurement unit 4 with a trigger signal synchronized with the time when the pulse in the laser light PL is output.

The ultrasonic pulse output unit 2 outputs ultrasonic pulses PU. The ultrasonic pulse output unit 2 supplies the measurement unit 4 with a trigger signal synchronized with the timing when the pulse in the ultrasonic pulse PU is output.

The measurement unit 4 measures the measurement object 200 based on the photoacoustic wave AW generated in the measurement object 200 by the reflected wave US of the ultrasonic pulse PU reflected by the measurement object 200 and the laser light PL. Note that the measurement unit 4 performs measurement in synchronization with trigger signals given from the laser light output device 1 and the ultrasonic pulse output unit 2 .

Next, the operation of the seventh embodiment will be explained.

A laser light output device 1 outputs a laser light PL. The laser light PL is similar to the third pulse (after filtering) P3b. The ultrasonic pulse output unit 32 outputs ultrasonic pulses PU.

Laser light PL and ultrasonic pulse PU are applied to object 200 to be measured. A photoacoustic wave AW is generated by applying the laser beam PL to the object 200 to be measured. When the ultrasonic pulse PU is applied to the object 200 to be measured, it is reflected. This reflected wave is the reflected wave US.

The measurement target 200 is measured by the measurement unit 4 based on the reflected wave US and the photoacoustic wave AW.

According to the seventh embodiment, by applying laser light PL and ultrasonic pulse PU to measurement object 200, optical ultrasonic measurement of measurement object 200 can be performed. Moreover, irradiating the measurement object 200 with pulsed light of a certain wavelength and then immediately irradiating it with pulsed light of another wavelength is the same as in the first, second, third, fourth and fifth embodiments. It is possible as well.

P1 1st pulse P2a 2nd pulse (before wavelength conversion)
P2b second pulse (after wavelength conversion)
P3a third pulse (before filtering)
P3b third pulse (after filtering)
OP1, OP2, OP3 optical path 1 laser light output device 10 excitation laser (pulse laser output unit)
11 Optical Attenuator (ATT)
12 acousto-optic modulator (optical path determination unit) (AOM)
120 acousto-optic deflector (AOD) (optical path determination unit)
13 rhomboid prism 14, 14a, 14b wavelength change section (PPLN)
142 LN crystal substrate 144 polarization reversal part 15, 154 mirror 16, 162, 164 dichroic mirror (multiplexer) (DCM)
17 filter (F)
18 optical fiber (MMF)
2 ultrasonic pulse output unit 4 measurement unit 100 photoacoustic wave measurement device 200 measurement object

Claims (18)

a laser light output device that outputs laser light;
a measurement unit that measures the measurement object based on photoacoustic waves generated in the measurement object by the laser light;
with
The laser light output device is
a pulse laser output unit that outputs a laser beam of a predetermined wavelength as a first pulse;
an optical path determination unit that receives the first pulse, determines and outputs an optical path to any one of a plurality of optical paths for each of the first pulses;
a wavelength changing unit that receives traveling light that has traveled through each of the plurality of optical paths, changes the wavelength to a different wavelength, and outputs the light;
a multiplexer for multiplexing the outputs of the wavelength changing unit;
A photoacoustic wave measurement device having The photoacoustic wave measurement device according to claim 1,
Equipped with an ultrasonic pulse output unit that outputs ultrasonic pulses,
The measurement unit further measures a reflected wave in which the ultrasonic pulse is reflected from the measurement object,
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to claim 1 or 2,
the first pulse has a predetermined frequency;
The optical path determining unit outputs a second pulse having a frequency obtained by dividing the predetermined frequency by the number of the plurality of optical paths and having a different phase from each of the plurality of optical paths.
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to claim 3,
the combiner outputs a third pulse having the predetermined frequency;
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to any one of claims 1 to 4,
wherein the pulsed laser output unit is an excitation laser;
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to any one of claims 1 to 4,
wherein the optical path determining unit is an acousto-optic modulator or an acousto-optic deflector;
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to any one of claims 1 to 4,
The wavelength changing section is
The traveling light propagates and has polarization inversion parts arranged at predetermined intervals,
wherein the predetermined interval is different for each traveling light;
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to claim 7,
The wavelength changing section is
Having a nonlinear optical crystal substrate on which the domain inversion part is formed,
the centroid of the polarization inversion portion is arranged on a straight line parallel to the x-axis of the nonlinear optical crystal substrate;
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to claim 7,
the wavelength changing portion has a nonlinear optical crystal substrate on which the polarization inversion portion is formed;
the centroid of the polarization inversion portion is arranged on a straight line parallel to the traveling direction of the traveling light,
the traveling direction of the traveling light is not parallel to the x-axis of the nonlinear optical crystal substrate;
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to claim 7,
A photoacoustic wave measuring device, wherein the wavelength changing portion has one nonlinear optical crystal substrate on which all the polarization inversion portions are formed. The photoacoustic wave measurement device according to claim 7,
The wavelength changing section is
Having a nonlinear optical crystal substrate on which the domain inversion part is formed,
The nonlinear optical crystal substrate is provided for each propagating traveling light,
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to any one of claims 1 to 4,
wherein the wavelength changing section has a nonlinear optical crystal through which the traveling light propagates;
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to any one of claims 1 to 4,
A photoacoustic wave measurement device comprising an optical fiber that receives the output of the multiplexer at one end and outputs the output from the other end. The photoacoustic wave measurement device according to any one of claims 1 to 4,
A photoacoustic wave measurement apparatus comprising a timing control section for adjusting the output of the optical path determination section to the timing of the output of the first pulse. The photoacoustic wave measurement device according to any one of claims 1 to 14,
The optical path determination unit is
a first acousto-optic modulator that receives the first pulse, determines and outputs one of a plurality of optical paths for each of the first pulses, and
a second acousto-optic modulator that receives the output of the first acousto-optic modulator, determines and outputs one of one or more optical paths for each pulse of the output of the first acousto-optic modulator; vessel and
A photoacoustic wave measurement device having The photoacoustic wave measurement device according to claim 15,
the first acousto-optic modulator diffracts or rectilinearly outputs each of the first pulses;
The second acousto-optic modulator receives the straightened first pulse, diffracts or straightens it, and outputs it, receives the diffracted first pulse, straightens it, and outputs it.
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to claim 15,
the first acousto-optic modulator diffracts or rectilinearly outputs each of the first pulses;
The second acousto-optic modulator receives a diffracted version of the first pulse, diffracts or straightens it, and outputs it, receives a straightened version of the first pulse, straightens it, and outputs it.
Photoacoustic wave measurement device. The photoacoustic wave measurement device according to claim 15,
the first acousto-optic modulator diffracts or rectilinearly outputs each of the first pulses;
The second acousto-optic modulator diffracts or rectilinearly outputs each pulse of the output of the first acousto-optic modulator.
Photoacoustic wave measurement device.

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