CN114941984A - Photoacoustic signal detection device and method of all-optical device - Google Patents

Abstract

The invention discloses a photoacoustic signal detection device and method of an all-optical device, and belongs to the technical field of photoacoustic signal detection. Photoacoustic signal excitation and collection are carried out by the excitation and detection system separation method of direct incidence of excitation light and oblique incidence of detection light. The oblique incidence of detection light can greatly improve the reflectivity of the surface of the object to be imaged to the detection light. The system efficiently reflects and collects the reflected light along the original optical path with a wide angular range. At the same time, the Mach-Zehnder interferometer coupled to the Michelson interferometer is used to measure the vertical displacement caused by the motion of the object to be imaged in real time, and control the space through feedback. The light modulator adjusts the distribution of the detection light in real time, so that the focal point is always located at the same position on the surface of the object to be imaged, so that the detection system can keep the relative intensity of the measurement signal and the key performance of the imaging resolution unchanged during the in vivo imaging. Robust photoacoustic signal detection under the condition of high spatial resolution.

Description

Photoacoustic signal detection device and method for all-optical device

technical field

The invention belongs to the technical field of photoacoustic signal detection, and in particular relates to a photoacoustic signal detection device and method of an all-optical device.

Background technique

Photoacoustic imaging photoacoustic imaging, PAI is a biomedical functional imaging method based on photoacoustic effect and mediated by ultrasound. Photoacoustic imaging has been widely used in the field of biomedical imaging due to its advantages of label-free, functional, high depth/spatial resolution ratio, multi-contrast and multi-scale. Among them, all-optical photoacoustic imaging still needs to overcome the limitations of low signal-to-noise ratio and surface flatness requirements due to the technical requirements of optical detection, and obtain more stable photoacoustic signals.

In the all-optical non-contact photoacoustic imaging based on the principle of interferometry, the excitation light and the probe light are usually coaxially and vertically incident to focus on the interior and surface of the object to be imaged or the surface of the coated acoustic coupling medium, respectively, and carry the object to be imaged. The reflected light of the object surface fluctuation information is coupled into the interferometer to generate an interference signal, and the photoacoustic signal is obtained by photoelectric detection. However, there are many problems in the existing imaging technology. First, the reflectivity of the surface of the living body or the coated acoustic coupling medium such as glycerol to common lasers such as 1064nm, 532nm, 1550nm, 1310nm, etc. is only 2% to 6%. As a result, only a very small part of the probe light can be coupled into the interferometer, and an effective photoacoustic signal cannot be obtained. Secondly, due to the uneven surface of the object to be imaged and the movement of the living animal itself, the surface of the object to be imaged and the probe beam used for interferometry cannot always be kept perpendicular to each other. Therefore, the reflected light carrying the surface relief information reflected by the surface of the object to be imaged cannot return to the optical path of the interferometer due to angular deflection, resulting in the loss of the photoacoustic signal. In order to realize photoacoustic signal detection, it is usually necessary to manually adjust the coupling between the reflected light and the interferometer, but the adjustment speed is extremely slow and the adjustment accuracy is low, which makes the existing all-optical non-contact photoacoustic imaging device based on the principle of interferometry. Imaging applications that cannot be applied to live animals and sample measurements in non-laboratory settings.

Existing all-optical non-contact photoacoustic imaging methods based on interferometry include heterodyne interferometer, confocal Fabry-Perot interferometer, or homodyne interferometer, the main purpose is to measure the light reaching the surface of the sample. Vibration of the sample surface caused by sound waves, but these methods still have certain limitations. First, these system devices often irradiate the object to be imaged in a coaxial manner with the excitation light and the detection light, so that the collection optical path of the signal light interferes with the illumination optical path of the excitation light and the detection light. Second, the all-optical device non-contact photoacoustic imaging system based on interferometry has poor stability. When the object to be imaged is a living organism, the breathing activity of the organism and any other small activities will cause reflections carrying photoacoustic signals. The detection light cannot be coupled into the interferometer, which basically has no practical clinical value.

Therefore, there is an urgent need in the art for an all-optical photoacoustic signal detection method that can achieve robust detection without reducing the spatial resolution of imaging.

SUMMARY OF THE INVENTION

In view of the current problems of low reflectivity at the interface of the surface of the object to be imaged or coated with glycerin and other acoustic coupling medium interfaces, and the method of interferometric detection of photoacoustic signals is difficult to meet the imaging requirements of living objects to be imaged or samples with uneven surfaces, it is impossible to To solve the problem of detecting a complete photoacoustic signal, the present invention provides a photoacoustic signal detection device and method of an all-optical device.

The purpose is to provide an all-optical device photoacoustic signal detection method that can achieve robust detection without reducing the imaging spatial resolution, which is suitable for real-time imaging methods of living organisms including the human body.

In order to achieve the above object, the present invention has adopted the following technical solutions:

A photoacoustic signal detection method of an all-optical device, in the case where the excitation light is vertically incident and focused into the object to be imaged, and the detection light is obliquely incident and focused on the surface of the object to be imaged, the reflected light carrying the surface fluctuation information of the object to be imaged passes through " After the "cat's eye" mirror returns along the original optical path, part of it is coupled into the fiber amplifier and undergoes Michelson interference with the reflected light of the reference arm. The photoacoustic signal is measured according to the small displacement caused by the photoacoustic on the surface of the object to be imaged; The Mach-Zehnder interferometer of the Johnson interferometer interferes with the light beam that is not incident on the surface of the object to be imaged. The vertical displacement caused by the motion of the object to be imaged is measured by the interference signal, and the spatial light modulator is fed back to control the detection light in real time. distribution, so that the focal point is always located at the same position on the surface of the object to be imaged, so that the photoacoustic signal can be collected to the maximum extent under the condition that the surface of the object to be imaged is uneven and small movements occur, and the robustness of the photoacoustic signal can be realized. probe.

The probe light and the excitation light are coaxially separated from the transmission system, the excitation light is vertically incident inside the object to be imaged, and the probe light is incident obliquely on the surface of the object to be imaged, and the reflected light path will not interfere with the excitation light and the probe light part.

The method uses a Michelson interferometer and a Mach-Zehnder interferometer to obtain photoacoustic signals and feedback to control the vertical motion caused by the motion of the object to be imaged.

This imaging method is suitable for excitation light and probe light of any wavelength.

A photoacoustic signal detection method of an all-optical device, comprising the following steps:

Step 1, the excitation light is vertically irradiated and focused inside the object to be imaged, and the absorber in the object to be imaged absorbs energy and expands by heat to generate an ultrasonic signal;

Step 2, the propagation of the ultrasonic signal causes a slight displacement on the surface of the object to be imaged or the surface of the coated acoustic coupling medium;

Step 3, the detection light is divided into two parts, one part is used as the reference arm of the Michelson interferometer, and the other part is the signal arm of the Michelson interferometer, and the detection light is obliquely incident on the surface of the object to be imaged or the surface of the coated acoustic coupling medium;

Step 4: After the detection light is obliquely incident on the surface of the object to be imaged or the surface of the coated acoustic coupling medium is reflected, the reflected light is reflected and collected by the "cat's eye" reflector on the original optical path; the appropriate lens parameters of the "cat's eye" reflector are selected, The maximum rotation angle of the surface of the object to be imaged can be tolerated by the interferometer;

Step 5: Use the Mach-Zehnder interferometer coupled to the Michelson interferometer to measure the displacement in the vertical direction caused by the motion of the object to be imaged; control the spatial light modulator through the feedback system, and adjust the distribution of the probe light in real time to make it The focus point is always located at the same position on the surface of the object to be imaged, thereby further solving the problems of uneven surface and small movements;

Step 6, using a fiber amplifier to amplify the weak photoacoustic signal measured;

Step 7, the amplified signal light and the reflected light in the reference arm enter the Michelson interferometer for interference, and the change of the interference signal reflects the fluctuation information of the surface of the object to be imaged;

In step 8, the photoacoustic signal is detected by the photodetector to realize the detection of the photoacoustic signal by the all-optical device.

A device for photoacoustic signal detection of all-optical devices, including laser, laser, A fiber circulator, B fiber circulator, C fiber circulator, 2*2A fiber coupler, and 1*2B with a beam splitting ratio of 50:50 Fiber coupler, 1*2C fiber coupler with split ratio of 99:1, 1*2D fiber coupler with split ratio of 99:1, 2*2E fiber coupler, fiber collimator, A lens, B Lenses, C lenses, D lenses, plane mirrors with piezoelectric ceramics on the back, oblique incidence systems, spatial light modulators, mirrors, fiber amplifiers, A-balanced detectors and B-balanced detectors, objects to be imaged; the detection device is suitable for for the detection of any acoustic signal.

The laser is provided with an emission port, and the emission port is used to emit continuous laser light; the laser is provided with an emission port, and the emission port is used to emit pulsed laser light; the A fiber circulator, B fiber circulator, and C fiber circulator are all provided. There are three ports, and the functions of the three ports are: when port 01 is used as input, port 02 is output; when port 02 is used as input, port 03 is output; port 03 cannot be used as input; the 2*2A fiber coupling The device has 4 ports, one receiving port and two output ports, the remaining one is an idle port, and the two output ports can be used as the receiving port for reflected light. At this time, the receiving port and the idle port are the output ports; so The 1*2 fiber optic coupler with the beam splitting ratio of 50:50 has 3 ports, one receiving port and two output ports, and when one of the output ports is used as the receiving port for reflected light, the receiving port becomes the output port. Port; the 1*2 optical fiber coupler with the splitting ratio of 99:1 and the 1*2 optical fiber coupler with the splitting ratio of 99:1 are provided with 3 ports, which are respectively a receiving port and two output ports; The 2*2E fiber coupler is provided with 4 ports, which are respectively two receiving ports and two output ports; the fiber collimator is provided with one port to connect the fiber, and the output light is free space collimated light; The lens focuses the collimated light; the flat mirror with piezoelectric ceramics on the back can change the phase difference between the reference arm and the signal arm by changing the scanning voltage loaded on the piezoelectric ceramics; the oblique incidence system is provided with 1 Each receiving port can also be used as an output port for reflected light, including B lens, C lens, D lens, spatial light modulator, mirror, and object to be imaged; the spatial light modulator regulates the distribution of probe light; the lens The excitation light is focused; the fiber amplifier is provided with 2 ports, which are a receiving port and an output port, respectively, to amplify the photoacoustic signal; the balanced detector and the balanced detector are provided with 2 receiving ports, which are used for for receiving signals;

The continuous laser output from the transmitting port is coupled into the A fiber circulator through the coupler, and then into the 2*2A fiber coupler; the 2*2A fiber coupler divides the output of the optical signal into two channels, one is set as the reference arm, The other is set as the signal arm;

The reference arm is composed of a fiber collimator, an A lens and a plane mirror with piezoelectric ceramics on the back; the signal arm is composed of a 1*2B fiber coupler with a split ratio of 50:50 and a split ratio of 99:1 1*2C fiber coupler, B fiber circulator, 1*2D fiber coupler with split ratio of 99:1, fiber amplifier, C fiber circulator, oblique incidence system, 2*2E fiber coupler, and B balance The composition of the detector;

One signal output from the 2*2A fiber coupler enters the fiber collimator through the fiber, and the collimated light in the free space output by the fiber collimator passes through the A lens and is focused on the plane mirror with the piezoelectric ceramic on the back to complete the reference arm. transmission;

The other signal output from the 2*2A fiber coupler enters the 1*2B fiber coupler with a split ratio of 50:50 through the fiber, and the 1*2B fiber coupler with a split ratio of 50:50 enters the split ratio through the fiber 1*2C fiber coupler with 99:1, 1*2D fiber coupler with beam splitting ratio of 99:1, 99% of the light beam is introduced into the B fiber circulator through the fiber, and 1% of the light beam enters the 2*2E through the fiber Fiber coupler; the light beam entering the B fiber circulator is transmitted from the output port to the oblique incidence system, and then passes through the spatial light modulator, C lens, object to be imaged, D lens, and mirror in the oblique incidence system, and the reflector converts the signal It is reflected along the original path and coupled to the receiving port of the B fiber circulator. The B fiber circulator transmits the received reflected signal through the output port to a 1*2D fiber coupler with a splitting ratio of 99:1. A 1*2D fiber coupler with a split ratio of 99:1 transmits 99% of the signal to the fiber amplifier and 1% to the 2*2E fiber coupler; the fiber amplifier transmits the signal to the C fiber In the circulator, the signal passing through the C fiber circulator re-enters the 1*2B fiber coupler with a split ratio of 50:50; the 1*2B fiber coupler with a split ratio of 50:50 reflects the signal through the fiber. It is transmitted to the 2*2A fiber coupler, 50% of the reflected signal is transmitted to the balanced detector, 50% of the reflected signal enters the A fiber circulator through the receiving port, and is transmitted to the balanced detector from the output port; *The signal of the 2B fiber coupler is transmitted to the balanced detector to complete the transmission of the signal arm.

Further, the laser is a narrow linewidth infrared laser; the laser is a pulsed excitation light.

A photoacoustic signal detection device using the above all-optical device is applied to the real-time imaging of living organisms.

The principle of the present invention is as follows: the traditional coaxial transmission system of excitation light and detection light is separated, the excitation light is vertically incident inside the object to be imaged, and the detection light obliquely enters the surface of the object to be imaged at a certain angle or is coupled with acoustic coupling such as coated glycerin The surface of the medium greatly improves the reflectivity of the surface of the object to be imaged to the detection light. And the reflected light path will not interfere with the excitation light and the detection light part. At the same time, the "cat's eye" mirror is used to efficiently reflect and collect the reflected probe light in a wide angle range and couple it into the optical fiber. The Mach-Zehnder interferometer coupled to the Michelson interferometer is used to treat the surface of the imaged object caused by its own activity. The small displacement in the vertical direction is measured in real time, and the spatial light modulator is controlled by the feedback system to adjust the distribution of the detection light in real time, so that the focus point is always at the same position on the surface of the object to be imaged. When the activity is small, key performances such as the relative intensity of the measurement signal and the imaging resolution of the all-optical photoacoustic imaging can be kept unchanged.

Compared with the prior art, the present invention has the following advantages:

1. The "cat's eye" mirror optical system is used to efficiently couple the reflected light carrying the surface fluctuation information of the object to be imaged into the optical fiber along the original optical path. The range of applications of acoustic imaging.

2. The laser adopts the incident method in which the transmission system of excitation light and detection light is separated, which greatly improves the reflectivity of common lasers on the surface of organisms or coated glycerin and other acoustic coupling media, and solves the problem that effective photoacoustic signals cannot be detected. question.

3. The Mach-Zehnder interferometer is introduced to measure the displacement in the vertical direction caused by the motion of the object to be imaged, and the spatial light modulator is controlled by feedback to control the distribution of the probe light in real time, so that the focal point is always located on the same surface of the object to be imaged. position, which solves the problem of uneven surface and small movement of the object to be imaged.

4. The all-optical device photoacoustic imaging method based on the interference principle designed by the method of the present invention can realize the all-optical photoacoustic imaging method with robust detection without reducing the imaging spatial resolution, and is suitable for including human body. real-time imaging of living organisms.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below.

Fig. 1 is the flow chart of the photoacoustic signal detection method of the all-optical device of the present invention;

Fig. 2 is the timing control diagram of the present invention;

3 is a schematic diagram of a photoacoustic signal detection device of an all-optical device of the present invention;

FIG. 4 is an enlarged schematic diagram of an oblique incident system provided in Embodiment 1 of the present invention.

Symbol description: 101, laser; 102, laser; 201, A fiber circulator; 202, B fiber circulator; 203, C fiber circulator; 301, 2*2A fiber coupler; 302, 2*2B fiber coupler; 303. 1*2C fiber coupler with a split ratio of 50:50; 304, 1*2D fiber coupler with a split ratio of 99:1; 305, 2*2E fiber coupler; 4. Fiber collimator; 501, A lens; 502, B lens; 503, C lens; 504, D lens; 6. Flat mirror with piezoelectric ceramics on the back; 7. Oblique incidence system; 8. Spatial light modulator; 9. Reflector; 10 , fiber amplifier; 1101, A balance detector; 1102, B balance detector; 12, object to be imaged.

Detailed ways

Example 1

An all-optical device photoacoustic signal detection device, comprising a laser 101, a laser 102, an A fiber circulator 201, a B fiber circulator 202, a C fiber circulator 203, a 2*2A fiber coupler 301, and a beam splitting ratio of 50 :50 1*2B fiber coupler 302, 1*2C fiber coupler 303 with a split ratio of 99:1, 1*2D fiber coupler 304 with a split ratio of 99:1, 2*2E fiber coupler 305 , fiber collimator 4, A lens 501, B lens 502, C lens 503, D lens 504, plane mirror 6 with piezoelectric ceramics on the back, oblique incidence system 7, spatial light modulator 8, mirror 9, fiber amplifier 10. A balance detector 1101 and B balance detector 1102, object 12 to be imaged; the detection device is suitable for detection of any acoustic signal.

The laser 101 is provided with an emission port, and the emission port is used to emit continuous laser light; the laser 102 is provided with a emission port, and the emission port is used to emit pulsed laser light; the A fiber circulator 201, the B fiber circulator 202, and the C fiber The circulator 203 is provided with three ports, and the functions of the three ports are that when the 01 port is used as the input end, the 02 port is the output end; when the 02 port is used as the input end, the 03 port is the output end; the 03 port cannot be used as the input end; the The 2*2A fiber optic coupler 301 has 4 ports, one receiving port and two output ports, the remaining one is an idle port, and the two output ports can be used as the receiving port for reflected light. At this time, the receiving port and the idle port are The port is an output port; the 1*2 optical fiber coupler 302 with the beam splitting ratio of 50:50 is provided with 3 ports, which are respectively a receiving port and two output ports, and one of the output ports is used as the receiving port of the reflected light. When , the receiving port becomes the output port; the 1*2 optical fiber coupler 303 with the splitting ratio of 99:1 and the 1*2 optical fiber coupler 304 with the splitting ratio of 99:1 are provided with 3 ports, which are respectively One receiving port and two output ports; the 2*2E fiber coupler 305 is provided with 4 ports, which are respectively two receiving ports and two output ports; the fiber collimator 4 is provided with 1 port to connect the fiber , the output light is free space collimated light; the lens 501 focuses the collimated light; the flat mirror 6 with the piezoelectric ceramic on the back can change the reference arm and the signal by changing the scanning voltage loaded on the piezoelectric ceramic The phase difference of the arm; the oblique incident system 7 is provided with a receiving port and can also be used as an output port for reflected light, including B lens 502, C lens 503, D lens 504, spatial light modulator 8, reflector 9, The object to be imaged 12; the spatial light modulator 8 regulates the distribution of the probe light; the lens 502 focuses the excitation light; the fiber amplifier 10 is provided with two ports, one receiving port and one output port, respectively. The photoacoustic signal is amplified; the balanced detector 1101 and the balanced detector 1102 are provided with two receiving ports for receiving signals;

The continuous laser output from the laser 101 from the transmitting port is coupled into the A fiber circulator 201 through the coupler, and then into the 2*2A fiber coupler 301; the 2*2A fiber coupler 301 divides the output of the optical signal into two channels, one set is the reference arm, and the other is set as the signal arm;

The reference arm is composed of a fiber collimator 4, an A lens 501 and a plane mirror 6 with a piezoelectric ceramic on the back; the signal arm is composed of a 1*2B fiber coupler 302 with a split ratio of 50:50, a split ratio of 1*2C fiber coupler 303 with 99:1, B fiber circulator 202, 1*2D fiber coupler 304 with split ratio of 99:1, fiber amplifier 10, C fiber circulator 203, oblique incidence system 7, 2*2E fiber coupler 305, and B balance detector 1102;

One signal output from the 2*2A fiber coupler 301 enters the fiber collimator 4 through the fiber, and the collimated light in the free space output by the fiber collimator 4 passes through the A lens 501 and focuses on the plane mirror 6 with the piezoelectric ceramic on the back , complete the transmission of the reference arm;

The other signal output from the 2*2A fiber coupler 301 enters the 1*2B fiber coupler 302 with a split ratio of 50:50 through the optical fiber, and the 1*2B fiber coupler 302 with a split ratio of 50:50 enters through the fiber A 1*2C fiber coupler 303 with a split ratio of 99:1, a 1*2D fiber coupler 304 with a split ratio of 99:1, 99% of the beam is introduced into the B fiber circulator 202 through the fiber, and 1% of the beam Enter the 2*2E fiber coupler 305 through the optical fiber; the light beam entering the B fiber circulator 202 is transmitted from the output port to the oblique incidence system 7, and sequentially passes through the spatial light modulator 8, the C lens 503, the object to be imaged in the oblique incidence system 7 12. After the D lens 504 and the reflector 9, the reflector 9 reflects the signal along the original path and couples it to the receiving port of the B fiber circulator 202. The B fiber circulator 202 transmits the received reflected signal to the output port through the output port. In the 1*2D fiber coupler 304 with a split ratio of 99:1, the 1*2D fiber coupler 304 with a split ratio of 99:1 transmits 99% of the signal to the fiber amplifier 10, and transmits 1% of the signal to the fiber amplifier 10. The signal is transmitted to the 2*2E fiber coupler 305; the fiber amplifier 10 transmits the signal to the C fiber circulator 203, and the signal passing through the C fiber circulator 203 re-enters the 1*2B fiber with a split ratio of 50:50 In the coupler 302; the 1*2B fiber coupler 302 with the beam splitting ratio of 50:50 transmits the reflected signal to the 2*2A fiber coupler 301 through the optical fiber, and 50% of the reflected signal is transmitted to the balanced detector 1102 , 50% of the reflected signal enters the A fiber circulator 201 through the receiving port, and is transmitted to the balanced detector 1102 from the output port; the signal passing through the 2*2B fiber coupler 302 is transmitted to the balanced detector 1102, completing the signal arm transmission.

Example 2

A photoacoustic signal detection method of an all-optical device, in the case where the excitation light is vertically incident and focused into the object to be imaged, and the detection light is obliquely incident and focused on the surface of the object to be imaged, the reflected light carrying the surface fluctuation information of the object to be imaged passes through " After the "cat's eye" mirror returns along the original optical path, part of it is coupled into the fiber amplifier and undergoes Michelson interference with the reflected light of the reference arm. The photoacoustic signal is measured according to the small displacement caused by the photoacoustic on the surface of the object to be imaged; The Mach-Zehnder interferometer of the Johnson interferometer interferes with the light beam that is not incident on the surface of the object to be imaged. The vertical displacement caused by the motion of the object to be imaged is measured by the interference signal, and the spatial light modulator is fed back to control the detection light in real time. distribution, so that the focal point is always located at the same position on the surface of the object to be imaged, so that the photoacoustic signal can be collected to the maximum extent under the condition that the surface of the object to be imaged is uneven and small movements occur, and the robustness of the photoacoustic signal can be realized. probe.

Example 3

A photoacoustic signal detection method of an all-optical device, comprising the following steps:

Step 1, the excitation light is vertically irradiated and focused inside the object to be imaged, and the absorber in the object to be imaged absorbs energy and expands by heat to generate an ultrasonic signal;

Step 2, the propagation of the ultrasonic signal causes a slight displacement on the surface of the object to be imaged or the surface of the coated acoustic coupling medium;

Step 3, the detection light is divided into two parts, one part is used as the reference arm of the Michelson interferometer, and the other part is the signal arm of the Michelson interferometer, and the detection light is obliquely incident on the surface of the object to be imaged or the surface of the coated acoustic coupling medium;

Step 4: After the detection light is obliquely incident on the surface of the object to be imaged or the surface of the coated acoustic coupling medium is reflected, the reflected light is reflected and collected by the "cat's eye" reflector on the original optical path; the appropriate lens parameters of the "cat's eye" reflector are selected, The maximum rotation angle of the surface of the object to be imaged can be tolerated by the interferometer;

Step 5: Use the Mach-Zehnder interferometer coupled to the Michelson interferometer to measure the displacement in the vertical direction caused by the motion of the object to be imaged; control the spatial light modulator through the feedback system, and adjust the distribution of the probe light in real time to make it The focus point is always located at the same position on the surface of the object to be imaged, thereby further solving the problems of uneven surface and small movements;

Step 6, using a fiber amplifier to amplify the weak photoacoustic signal measured;

Step 7, the amplified signal light and the reflected light in the reference arm enter the Michelson interferometer for interference, and the change of the interference signal reflects the fluctuation information of the surface of the object to be imaged;

In step 8, the photoacoustic signal is detected by the photodetector to realize the detection of the photoacoustic signal by the all-optical device.

This embodiment uses specific examples to illustrate the principles and implementations of the present invention. The descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention; meanwhile, for those skilled in the art, according to this There will be changes in the specific implementation manner and application scope of the idea of the invention. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Contents that are not described in detail in the specification of the present invention belong to the prior art known to those skilled in the art. Although the illustrative specific embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, As long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the inventive concept are included in the protection list.

Claims (5)

1. A photoacoustic signal detection method for an all-optical device, characterized in that: when the excitation light is vertically incident and focused on the interior of the object to be imaged, and the detection light is obliquely incident and focused on the surface of the object to be imaged, the surface undulations of the object to be imaged are carried. After the reflected light of the information returns along the original optical path through the "cat's eye" mirror, a part of it is coupled into the fiber amplifier, and undergoes Michelson interference with the reflected light of the reference arm, and the photoacoustic signal is measured according to the tiny displacement caused by the photoacoustics on the surface of the object to be imaged; The other part of the incoming coupling interferes with the light beam that is not incident on the surface of the object to be imaged in the Mach-Zehnder interferometer of the Michelson interferometer. The vertical displacement caused by the motion of the object to be imaged is measured by the interference signal, and the spatial light modulation is feedback controlled. It can adjust the distribution of the detection light in real time, so that the focus point is always at the same position on the surface of the object to be imaged, so that the photoacoustic signal can be collected to the maximum extent under the condition that the surface of the object to be imaged is uneven and small movements occur, so as to achieve robust Detection of Rod Photoacoustic Signals. 2. The photoacoustic signal detection method of an all-optical device according to claim 1, characterized in that: comprising the following steps: Step 1, the excitation light is vertically irradiated and focused inside the object to be imaged, and the absorber in the object to be imaged absorbs energy and expands by heat to generate an ultrasonic signal; Step 2, the propagation of the ultrasonic signal causes a slight displacement on the surface of the object to be imaged or the surface of the coated acoustic coupling medium; Step 3, the detection light is divided into two parts, one part is used as the reference arm of the Michelson interferometer, and the other part is the signal arm of the Michelson interferometer, and the detection light is obliquely incident on the surface of the object to be imaged or the surface of the coated acoustic coupling medium; Step 4: After the detection light is obliquely incident on the surface of the object to be imaged or the surface of the coated acoustic coupling medium is reflected, the reflected light is reflected and collected by the "cat's eye" reflector on the original optical path; the appropriate lens parameters of the "cat's eye" reflector are selected, The maximum rotation angle of the surface of the object to be imaged can be tolerated by the interferometer; Step 5: Use the Mach-Zehnder interferometer coupled to the Michelson interferometer to measure the displacement in the vertical direction caused by the motion of the object to be imaged; control the spatial light modulator through the feedback system, and adjust the distribution of the probe light in real time to make it The focus point is always located at the same position on the surface of the object to be imaged, thereby further solving the problems of uneven surface and small movements; Step 6, using a fiber amplifier to amplify the weak photoacoustic signal measured; Step 7, the amplified signal light and the reflected light in the reference arm enter the Michelson interferometer for interference; In step 8, the photoacoustic signal is detected by the photodetector to realize the detection of the photoacoustic signal by the all-optical device. 3. An all-optical device photoacoustic signal detection device, characterized in that: comprising a laser (101), a laser (102), an A fiber circulator (201), a B fiber circulator (202), a C fiber circulator ( 203), 2*2A fiber coupler (301), 1*2B fiber coupler with a split ratio of 50:50 (302), 1*2C fiber coupler with a split ratio of 99:1 (303), split 1*2D fiber coupler (304), 2*2E fiber coupler (305), fiber collimator (4), A lens (501), B lens (502), C lens ( 503), D lens (504), flat mirror with piezoelectric ceramic on the back (6), oblique incidence system (7), spatial light modulator (8), mirror (9), fiber amplifier (10), A balance a detector (1101), a B-balanced detector (1102), an object to be imaged (12); The laser (101) is provided with an emission port, which is used for emitting continuous laser light; the laser (102) is provided with an emission port, and the emission port is used for emitting pulsed laser light; the A fiber circulator (201), the B fiber The circulator (202) and the C-fiber circulator (203) are both provided with three ports. The functions of the three ports are that when port 01 is used as an input end, port 02 is an output end; when port 02 is used as an input end, port 03 is an output end. ; The 03 port cannot be used as an input end; the 2*2A fiber optic coupler (301) is provided with 4 ports, one receiving port and two output ports, the remaining one is an idle port, and the two output ports can be used as reflection The light receiving port, at this time, the receiving port and the idle port are output ports; the 1*2 optical fiber coupler (302) with a splitting ratio of 50:50 is provided with three ports, one receiving port and two output port, and when one of the output ports is used as the receiving port of the reflected light, the receiving port becomes the output port; the 1*2 fiber coupler (303) with a splitting ratio of 99:1 and a splitting ratio of 99:1 The 1*2 fiber coupler (304) is provided with 3 ports, which are one receiving port and two output ports; the 2*2E fiber coupler (305) is provided with 4 ports, which are two receiving ports respectively and two output ports; the optical fiber collimator (4) is provided with one port to connect the optical fiber, and the output light is free space collimated light; the lens (501) focuses the collimated light; The flat mirror (6) of the piezoelectric ceramic can change the phase difference between the reference arm and the signal arm by changing the scanning voltage loaded on the piezoelectric ceramic; the oblique incident system (7) is provided with a receiving port and can also be used as a reflection The light output port includes a B lens (502), a C lens (503), a D lens (504), a spatial light modulator (8), a mirror (9), and an object to be imaged (12); the spatial light modulation The device (8) regulates the distribution of the probe light; the lens (502) focuses the excitation light; the optical fiber amplifier (10) is provided with two ports, which are a receiving port and an output port, respectively, for the photoacoustic signal. Amplification; the balanced detector (1101) and the balanced detector (1102) are provided with two receiving ports for receiving signals; The continuous laser output from the laser (101) from the transmitting port is coupled into the A fiber circulator (201) through the coupler, and then into the 2*2A fiber coupler (301); the 2*2A fiber coupler (301) converts the optical signal The output is divided into two channels, one is set as the reference arm, and the other is set as the signal arm; The reference arm is composed of a fiber collimator (4), an A lens (501) and a plane mirror (6) with piezoelectric ceramics adhered to the back; the signal arm is coupled by a 1*2B fiber with a beam splitting ratio of 50:50 (302), a 1*2C fiber coupler (303) with a split ratio of 99:1, a B fiber circulator (202), a 1*2D fiber coupler with a split ratio of 99:1 (304), optical fibers Amplifier (10), C fiber circulator (203), oblique incidence system (7), 2*2E fiber coupler (305), and B balance detector (1102); One signal output from the 2*2A fiber coupler (301) enters the fiber collimator (4) through the fiber, and the collimated light output from the fiber collimator (4) in free space passes through the A lens (501) and is focused on the back adhesive On the plane mirror (6) with piezoelectric ceramics, the transmission of the reference arm is completed; The other signal output from the 2*2A fiber coupler (301) enters the 1*2B fiber coupler (302) with a split ratio of 50:50 through the optical fiber, and a 1*2B fiber coupler with a split ratio of 50:50 (302) Enter a 1*2C fiber coupler (303) with a splitting ratio of 99:1 through an optical fiber, a 1*2D fiber coupler (304) with a splitting ratio of 99:1, and introduce 99% of the light beam through the optical fiber B fiber circulator (202), 1% of the light beam enters the 2*2E fiber coupler (305) through the fiber; the light beam entering the B fiber circulator (202) is transmitted from the output port to the oblique incidence system (7), and sequentially passes through the oblique incidence system (7). After entering the spatial light modulator (8), the C lens (503), the object to be imaged (12), the D lens (504), and the reflecting mirror (9) in the system (7), the reflecting mirror (9) transmits the signal along the original direction. The reflected signal is coupled to the receiving port of the B fiber circulator (202), and the B fiber circulator (202) transmits the received reflected signal through the output port to a 1*2D fiber coupler with a splitting ratio of 99:1 In (304), the 1*2D fiber coupler (304) with a split ratio of 99:1 transmits 99% of the signal to the fiber amplifier (10), and transmits 1% of the signal to the 2*2E fiber coupler The fiber amplifier (10) transmits the signal to the C fiber circulator (203), and the signal passing through the C fiber circulator (203) re-enters the 1*2B fiber with a split ratio of 50:50 In the coupler (302); the 1*2B optical fiber coupler (302) with the beam splitting ratio of 50:50 transmits the reflected signal to the 2*2A optical fiber coupler (301) through the optical fiber, and 50% of the reflected signal is transmitted In the balanced detector (1102), 50% of the reflected signal enters the A fiber circulator (201) through the receiving port, and is transmitted to the balanced detector (1102) from the output port; through the 2*2B fiber coupler (302) ) signal is transmitted to the balanced detector (1102) to complete the transmission of the signal arm. The photoacoustic signal detection device of an all-optical device according to claim 3, characterized in that: the laser (101) is a narrow linewidth infrared laser; and the laser (102) is a pulse excitation light. 5. An application of the photoacoustic signal detection device using the all-optical device of claim 3 to real-time imaging of living organisms.

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