CN114190974A - Ultrasonic imaging system and imaging method thereof - Google Patents
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Abstract
The invention discloses an ultrasonic imaging system and an imaging method thereof, wherein the ultrasonic imaging system of one embodiment comprises: a sensor module configured to modulate an external ultrasonic signal and output a plurality of modulated optical signals of preset wavelengths; a time division multiplexing module configured to output a delay modulated optical signal under a preset delay amount based on the modulated optical signal; and the optical signal acquisition module is configured to generate a photoacoustic imaging picture according to the delay modulation optical signal. The ultrasonic imaging system of the embodiment of the invention modulates external ultrasonic signals into a plurality of modulation optical signals with preset wavelengths through the sensor module to be output, delays the plurality of modulation lights by utilizing the time division multiplexing module to avoid interference, and the optical signal acquisition module acquires the same ultrasonic signal in parallel according to mutually independent delay modulation optical signals, so that a photoacoustic imaging picture with higher imaging quality is generated.
Description
Technical Field
The invention relates to the technical field of ultrasound. In particular, the present invention relates to an ultrasound imaging system and an imaging method thereof.
Background
In biomedical imaging systems such as ultrasound imaging, photoacoustic imaging, etc., an ultrasound sensor array is a key component of the imaging system. The sensor array is composed of a plurality of ultrasonic sensor array elements in a certain spatial arrangement mode, and a target biological tissue structure can be reconstructed based on an acoustic phase synthesis method on the basis of ultrasonic signals detected by each array element, so that an imaging basis is provided for medical diagnosis.
The prior art photoacoustic imaging systems mainly include piezoelectric material based ultrasonic sensors and include fiber optic ultrasonic sensors. However, when the mainstream technology uses a plurality of ultrasonic sensors as array elements in an ultrasonic sensor array, the cost of the ultrasonic sensor based on a piezoelectric material is high, which greatly increases the cost of the photoacoustic imaging system, and there is a problem that the imaging quality is low due to mutual interference among the plurality of ultrasonic sensor array elements.
The optical fiber ultrasonic sensor is a novel sensor which takes optical fibers as sensitive media and converts the acoustic action of ultrasonic waves into optical signal change. US6839496B1 discloses an ultrasonic imaging system based on an optical fiber ultrasonic sensor, wherein an interferometer structure is designed on the end face of an optical fiber, the thickness of a sensitive film of the optical fiber is changed due to ultrasonic action, and the interference spectrum drift of reflected light is realized, however, the ultrasonic imaging system cannot realize the parallel detection of the same ultrasonic signal.
Disclosure of Invention
In order to solve at least one of the above-mentioned problems, a first embodiment of the present invention provides an ultrasound imaging system including:
a sensor module configured to modulate an external ultrasonic signal and output a plurality of modulated optical signals of preset wavelengths;
a time division multiplexing module configured to output a delay modulated optical signal under a preset delay amount based on the modulated optical signal;
and the optical signal acquisition module is configured to generate a photoacoustic imaging picture according to the delay modulation optical signal.
Further, the sensor module comprises optical fiber ultrasonic sensors with different preset wavelengths; wherein the fiber optic ultrasonic sensor comprises:
a laser light source unit configured to emit incident laser light;
an optical fiber assembly connected to the semiconductor laser and configured to modulate and output an external ultrasonic signal based on the incident laser light; and
and the reflection grating cavity mirrors are positioned on the optical fibers in pairs.
Further, the optical fiber includes rare earth ions.
Further, the time division multiplexing module includes:
a wavelength division multiplexer: the optical fiber is configured to receive the modulated optical signals with the preset wavelengths and output the modulated optical signals through the same optical fiber line;
a gating switch configured to select a modulated optical signal that satisfies a preselected time threshold in accordance with the preselected time threshold;
a circulator configured to direct the modulated light signal that satisfies the preselected time threshold to the reflective delay unit;
a reflection delay unit corresponding to the preset wavelength configured to reflect and delay the modulated optical signal corresponding to the preset wavelength, so that the circulator outputs a delayed modulated optical signal.
Further, the reflection delay unit includes: narrow-band reflection components and delay optical fibers which are alternately arranged;
the narrow-band reflection component comprises at least one narrow-band reflection piece corresponding to the preset wavelength;
the delay optical fiber assembly comprises a delay optical fiber arranged on one side of the narrow-band reflecting piece far away from the circulator or a delay optical fiber arranged between the adjacent narrow-band reflecting pieces.
Further, the optical signal acquisition module includes:
a photoelectric conversion unit configured to output a delay-modulated electrical signal in accordance with the delay-modulated optical signal:
a signal demodulation unit configured to demodulate the delay-modulated electric signal;
an image processing unit configured to generate a photoacoustic imaging picture from the delay-modulated electrical signal.
Further, the photoelectric conversion unit includes:
an amplifier configured to amplify the delay-modulated optical signal;
a photodetector configured to convert the delay-modulated optical signal into the delay-modulated electrical signal;
the frequency conversion unit is configured to carry out frequency conversion processing on the modulated electric signal;
and the analog-to-digital conversion unit is configured to discretize the modulated electric signal subjected to frequency conversion processing.
Further, the signal demodulation unit is further configured to restore the discretized frequency conversion processed modulated electrical signal and output the delayed modulated electrical signal.
Further, the optical fiber ultrasonic sensor is a wavelength modulation type sensor or a frequency modulation type sensor;
or
The optical fiber ultrasonic sensor also comprises a single polarization type optical fiber sensor;
the optical signal acquisition module further comprises an unbalanced interferometer configured to convert the delay modulation optical signal into an optical intensity signal and output the optical intensity signal to the photodetector;
or
The optical fiber ultrasonic sensor also comprises a single-frequency output type optical fiber sensor;
the optical signal acquisition module also comprises an unbalanced interferometer combined with a photoelectric detector, and is configured to convert the delay modulation optical signal into an optical intensity signal and output the optical intensity signal to the photoelectric detector; or
The fiber-optic ultrasonic sensor further comprises a passive fiber-optic resonant cavity configured to output the modulated optical signal;
the optical signal acquisition module further comprises a frequency comb configured to detect frequency information of the modulated optical signal output by the passive optical fiber optical resonant cavity and output the frequency information to the photodetector;
or
The fiber-optic ultrasonic sensor further comprises a passive fiber-optic resonant cavity configured to output the modulated optical signal;
the optical signal acquisition module further comprises a tunable laser configured to detect frequency information of the modulated optical signal output by the passive optical fiber resonator and output the frequency information to the photodetector.
A second embodiment of the present invention provides a method of ultrasound imaging using the ultrasound imaging system described above, comprising
Modulating according to an external ultrasonic signal and outputting a plurality of modulated optical signals with preset wavelengths;
outputting a delay modulation optical signal under a preset delay amount based on the modulation optical signal;
and generating a photoacoustic imaging picture according to the delay modulation optical signal.
The invention has the following beneficial effects:
according to the embodiment of the invention, the external ultrasonic signals are modulated into the modulated light signals with the preset wavelengths by the sensor module to be output, the plurality of modulated lights are delayed by the time division multiplexing module to avoid interference, and the optical signal acquisition module generates the photoacoustic imaging picture according to the mutually independent delayed modulated light signals.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 illustrates a block diagram of a frame of an ultrasound imaging system in accordance with an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a fiber-optic ultrasonic sensor according to an embodiment of the invention;
FIG. 3 shows an output spectrum diagram of a modulated optical signal of the output of a fiber optic ultrasonic sensor of an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a time division multiplexing module according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an optical signal acquisition module according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram illustrating a specific example of an optical signal acquisition module according to an embodiment of the present invention;
FIG. 7 shows a schematic diagram of a modulated light signal sequence generated by an ultrasound imaging system of an embodiment of the present invention;
FIGS. 8a and 8b show a picture of a target tissue and a photo-acoustic imaging picture obtained using a photo-acoustic imaging system of an embodiment of the present invention, respectively;
fig. 9 shows a flow chart of a proposed ultrasound imaging method according to another embodiment of the invention.
Detailed Description
In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.
It is noted that references herein to "on … …", "formed on … …" and "disposed on … …" can mean that one layer is formed or disposed directly on another layer or that one layer is formed or disposed indirectly on another layer, i.e., there is another layer between the two layers. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The existing medical ultrasonic sensor is mainly based on a piezoelectric material and converts an ultrasonic signal into an electric signal to be output. The medical ultrasonic sensing system comprises a plurality of ultrasonic sensor arrays, and each ultrasonic sensor array element is provided with an independent preamplifier, a filter and a signal acquisition module. In the prior art, the number of array elements in the ultrasonic sensor array with a large number is set, so that the target tissue structure is accurately restored, and an imaging result with higher quality is obtained. However, due to the limitation of the array mode, the cost of the array is increased proportionally when the number of the array elements of the ultrasonic sensor is increased. In addition, electromagnetic crosstalk inevitably exists between array elements in a large-scale ultrasonic sensor array, and even if the number of the array elements of the ultrasonic sensor is continuously increased, better imaging quality cannot be obtained.
In the photoacoustic imaging system in the prior art, an optical fiber ultrasonic sensor is also utilized to form the photoacoustic imaging system, a plurality of ultrasonic sensor array elements with different working wavelengths form an array, and in a signal acquisition mode, a tunable laser is required to be adopted to respectively acquire signals of each sensor through wavelength scanning, so that the parallel detection of the same ultrasonic field signal cannot be realized.
However, the photoacoustic imaging system has the problems of high cost and low imaging quality, and in order to solve the problems, the application provides an ultrasonic imaging system and an imaging method thereof.
A first embodiment of the present invention proposes an ultrasound imaging system, as shown in fig. 1, which includes:
a sensor module configured to modulate an external ultrasonic signal and output a plurality of modulated optical signals of preset wavelengths;
a time division multiplexing module configured to output a delay modulated optical signal under a preset delay amount based on the modulated optical signal;
and the optical signal acquisition module is configured to generate a photoacoustic imaging picture according to the delay modulation optical signal.
According to the photoacoustic imaging system, the external ultrasonic signals are modulated into the modulated light signals with the preset wavelengths through the sensor module to be output, the modulated lights are delayed by the time division multiplexing module to avoid interference, and the optical signal acquisition module generates the photoacoustic imaging picture according to the mutually independent delayed modulated light signals.
In the embodiment of the invention, on one hand, the multiplexing performance of the optical fiber ultrasonic sensor imaging is utilized, that is, the signal acquisition of a plurality of sensors in the sensor module can be realized through one optical signal acquisition module, and the parallel modulation and acquisition of the same external ultrasonic signal are realized, so that the imaging quality of the photoacoustic imaging picture is effectively improved. Furthermore, electromagnetic crosstalk does not exist among the plurality of optical fiber sensors in the sensor module, and the imaging quality is further improved. On the other hand, the embodiment of the invention only adopts one optical signal acquisition module, thereby effectively avoiding the problem of cost occupation caused by higher cost of the optical signal acquisition module, effectively reducing the system cost on the basis of realizing high-quality imaging and having wide application prospect.
In an alternative embodiment, the sensor module comprises fiber optic ultrasonic sensors of different preset wavelengths; the optical fiber ultrasonic sensor 1 includes a laser light source unit 11, an optical fiber 12, and reflection grating cavity mirrors 123 located on the optical fiber 12 and arranged in pairs.
The laser light source unit 11 is configured to emit incident laser light. In one specific example, the laser light source unit of the embodiment of the present invention includes a semiconductor laser capable of outputting a pump light source of incident laser light having a wavelength of 980mm, so that the fiber ultrasonic sensor forms laser output of continuous light at a gain wavelength after injection of the pump light.
The optical fiber 12 is connected to the semiconductor laser, and modulates and outputs an external ultrasonic signal based on the incident laser light.
In an alternative embodiment, the core of the optical fiber, the optical fiber comprises rare earth ions. The optical fiber of the sensor provided by the embodiment of the invention contains rare earth ions, and the rare earth doped ions can provide optical gain so as to improve the imaging quality. In one particular example, the optical fiber is an erbium-ytterbium co-doped fiber.
And reflection grating cavity mirrors 123 arranged in pairs on the optical fiber 12, the reflection grating cavity mirrors 123 having a high reflectivity for providing optical feedback. The laser output wavelength is determined by the reflection wavelength of the grating reflector, in a specific example, the distance between grating cavity mirrors is less than 8mm, so that single-frequency laser output is ensured in both x and y orthogonal polarization directions, and the corresponding output laser wavelength is between 1525 and 1565 nm. In the embodiment of the invention, the sensor module comprises a plurality of optical fiber ultrasonic sensors, and the working wavelength of each optical fiber ultrasonic sensor is different, so that an external ultrasonic signal can be modulated into the corresponding working wavelength and output. In a specific example, the optical fiber ultrasonic sensor of the embodiment of the invention has detection capability on ultrasonic signals in a range from 1MHz to 50MHz, and has a wide application prospect.
In one specific example, the sensor module includes 4 fiber-optic ultrasonic sensors with different preset wavelengths, fig. 3 shows the output spectrum of each fiber-optic ultrasonic sensor at the output end, and the 4 operating wavelengths are 1542.4, 1544.2, 1550.3 and 1551.7nm respectively. The 4 optical fiber ultrasonic sensors with different working wavelengths are arrayed according to the form of the corresponding target tissue and the structural characteristics of the target tissue. For example, a plurality of fiber optic ultrasound sensors are arrayed in a linear, circular, or like geometry. The embodiment of the present invention does not limit the specific array structure of the optical fiber ultrasonic sensor in the sensor module, and those skilled in the art perform the setting according to the actual application, which is not described herein again.
Furthermore, by utilizing the birefringence characteristic of the reflection grating cavity mirror in the optical fiber fixing tube, because of weak birefringence in the optical fiber, the output frequencies of the two orthogonal lasers in the x and y directions have a certain frequency difference. The optical fiber ultrasonic sensor responds to incident ultrasonic waves to be detected, the optical fiber can generate micro deformation, laser frequency drifts in the x direction and the y direction, and beat frequency signals also move in frequency, so that modulated optical signals fx and fy generated by responding to external ultrasonic signals are output to the optical signal acquisition module. In one particular example, the beat signal frequency is between 0.1GHz and 2.5 GHz.
Therefore, the sensor module provided by the embodiment of the invention can be used for simultaneously acquiring signals of a target tissue, avoiding electromagnetic crosstalk among a plurality of optical fiber ultrasonic sensors on the basis of ensuring that an ultrasonic modulation signal can accord with the real characteristics of the target tissue, and effectively improving the imaging quality.
In an alternative embodiment, as shown in fig. 4, the time division multiplexing module 2 includes:
the wavelength division multiplexer 21: configured to receive the modulated optical signals (λ 1, λ 2, λ 3 to λ N) of the plurality of preset wavelengths and output them through the same optical fiber line;
a gating switch 22 configured to select the modulated optical signal that satisfies a preselected time threshold in accordance with the preselected time threshold;
a circulator 23 configured to direct the modulated light signal satisfying the preselected time threshold to the reflective delay unit;
a reflection delaying unit 24 corresponding to the preset wavelength configured to reflect and delay the modulated optical signal corresponding to the preset wavelength.
In this embodiment, the wavelength division multiplexer has input channels with different operating wavelengths, and the operating wavelength of each input channel corresponds to the preset wavelength of the sensor module, so that a plurality of modulated optical signals with different wavelengths are respectively connected to the independent input channels to avoid crosstalk, and the modulated optical signals with different wavelengths in each independent channel are output to the gating switch through one optical fiber line.
In a specific example, as shown in fig. 4, the wavelength division multiplexer includes a plurality of input terminals, each of which is capable of accessing modulated optical signals λ 1, λ 2, λ 3 to λ N corresponding to a preset wavelength of the sensor module, and combines the modulated optical signals λ 1, λ 2, λ 3 to λ N operating at different wavelengths into a same optical fiber line through a same output terminal to be output to the gating switch.
The gating switch of the embodiment of the invention comprises an optical switch, the optical switch gates and switches the passing modulated optical signals in time, only the modulated optical signals containing a preselected time threshold t pass, and the modulated optical signals in other time intervals do not pass. As shown in fig. 4, the modulated optical signal λ 1 satisfies the current preselected time threshold for gating on light, and thus only one of the modulated optical signals λ 1, λ 2, and λ 3 at different wavelengths passes through. Within the next preset time threshold t, only the modulated optical signal λ 2 may pass.
It should be noted that the present invention is not limited to a specific preset time threshold, and a person skilled in the art should select a corresponding preset time threshold according to practical applications to implement that the gating switch only passes through one modulated optical signal that meets the preset time threshold as a design criterion, which is not described herein again.
Further, the circulator 23 is configured to guide the modulated optical signal meeting the preselected time threshold to the reflection delay unit 24, and the reflection delay unit 24 reflects and delays the modulated optical signal corresponding to the preset wavelength. In the present embodiment, the reflection delay unit 24 includes a plurality of narrow-band reflection components 241 corresponding to the wavelengths of the modulated optical signals, that is, the modulated optical signal λ 1 can be guided onto the narrow-band reflection component 241 corresponding to the wavelength thereof by the circulator, and the modulated optical signal λ 2 can be guided onto the narrow-band reflection component 241 corresponding to the wavelength thereof by the circulator, so as to isolate each modulated optical signal from each other after being delayed, thereby avoiding crosstalk between the modulated optical signals.
In an alternative embodiment, as shown in fig. 4, the reflective delay unit 24 includes: narrow-band reflection members 241 and delay fibers 242 alternately arranged;
the narrow band reflection assembly 241 includes at least one narrow band reflection member corresponding to the preset wavelength. The reflection wavelength of each narrow-band reflection piece is matched with the working wavelength of each optical fiber ultrasonic sensor, and only signals of the wavelength can be reflected.
The delay fiber 242 includes: a delay fiber disposed on a side of the narrowband reflecting member 241 remote from the circulator 23 or a delay fiber disposed between adjacent narrowband reflecting members. In a specific example, a section of delay fiber is inserted between two adjacent narrow-band reflectors, and the delay fiber matched with the first narrow-band reflector closest to the circulator is arranged on the side of the first narrow-band reflector far away from the circulator.
The length of the delay optical fiber determines the delay time of the signal, so that the modulated optical signals of two adjacent working wavelengths are completely separated in time, and crosstalk is effectively avoided. The modulated optical signals of the respective wavelengths, which are completely staggered in time, are transmitted to the ring again and output.
Specifically, the relationship between the length L of the delay fiber and the delay time T is T ═ L/2c, where c is the propagation speed of light in the fiber. In a specific example, to achieve complete separation of the modulated optical signals of two adjacent wavelengths in time, the delay time T should be greater than or equal to a preset time threshold T, so that a certain blank interval exists between the time windows of each wavelength. Specifically, as an example, the time delay between two adjacent fiber optic ultrasonic sensors is 15 microseconds, considering that the speed of light in the fiber is about 2 × 108m/s, corresponding to a delay time of 1.5 km. The time window for each sensor signal light is 10 microns, considering that the speed of sound in biological tissue is about 1500m/s, corresponding to an imaging depth of about 1.5 cm.
The embodiment of the present invention does not limit the delay time of the delay optical fiber, and those skilled in the art should appropriately delay the modulated optical signals with each preset wavelength according to actual requirements, so that the modulated optical signals have respective time windows and are staggered with each other, and no overlapping interval is taken as a design criterion, which is not described herein again.
The modulated optical signal of the embodiment of the invention is delayed by the reflection delay unit and then output to the circulator again, so that the circulator outputs the delayed modulated optical signal to the optical signal acquisition module, and the optical signal acquisition module can convert and demodulate the delayed modulated optical signal and generate the photoacoustic imaging picture.
In an alternative embodiment, as shown in fig. 5, the optical signal acquisition module 3 comprises:
a photoelectric conversion unit 31 configured to output a delay-modulated electrical signal in accordance with the delay-modulated optical signal:
a signal demodulation unit 32 configured to demodulate the delay-modulated electric signal;
an image processing unit 33 configured to generate a photoacoustic imaging picture from the delay-modulated electric signal.
In an alternative embodiment, as shown in fig. 6, the photoelectric conversion unit 31 includes:
an amplifier 311 configured to amplify the delay-modulated optical signal;
a photodetector 312 configured to convert the delay-modulated optical signal into the delay-modulated electrical signal;
a frequency conversion unit 313 configured to perform frequency conversion processing on the modulated electrical signal;
and the analog-to-digital conversion unit 314 is configured to discretize the frequency-converted modulated electrical signal.
In this embodiment, amplifier 311 amplifies the delay modulated optical signal, and in one specific example, the amplifier comprises an erbium doped fiber amplifier. The Photodetector (PD)312 acquires the amplified delay-modulated optical signal and performs photoelectric conversion. In one particular example, the bandwidth of the photodetector is greater than or equal to 5 GHz. The frequency conversion unit 313 further performs frequency conversion on the modulated electrical signal, specifically, performs down-conversion on the photoelectrically converted delay modulated optical signal, and performs frequency mixing with the incident modulated signal of the optical fiber sensor through the local microwave source, thereby implementing quadrature down-conversion. The analog-to-digital conversion unit 314 discretizes the modulated electrical signal subjected to frequency conversion processing and then collects the discretized modulated electrical signal. In one particular example, the acquired modulated electrical signal is low pass filtered to improve the signal-to-noise ratio. The signal demodulation unit demodulates the acquired modulation electric signal and enables the image processing unit to generate a photoacoustic imaging picture according to the delay modulation electric signal.
In an optional embodiment, the signal demodulating unit 32 is further configured to recover the discretized frequency-conversion processed modulated electrical signal and output the delayed modulated electrical signal.
In a specific example, the two orthogonal delay modulation electrical signals q (t) and i (t) collected by the analog-to-digital conversion unit form an included angle
And the included angle
And the relationship between the mutually orthogonal delay modulated electrical signals q (t) and i (t) is:
in a specific example, the sensor module responds to the generation frequency modulation of the ultrasonic wave signal as a derivative of phase with respect to time, and restores an original modulated light signal through a derivation operation, fig. 7 is an original modulated light signal sequence obtained according to an embodiment of the present invention, as shown in fig. 7, an original modulated light signal # 1 corresponds to a modulated light signal λ 1, an original modulated light signal # 2 corresponds to a modulated light signal λ 2, an original modulated light signal # 3 corresponds to a modulated light signal λ 3, an original modulated light signal # 4 corresponds to a modulated light signal λ 4, and modulated light signals of preset wavelengths corresponding to a plurality of fiber ultrasonic sensors in the sensor module are mutually independent in time, and do not generate crosstalk, which effectively ensures the imaging quality of a photoacoustic imaging picture generated according to the modulated light signals.
Fig. 8a and 8b show a picture of a target tissue and a photo acoustic imaging picture obtained by the photo acoustic imaging system of the embodiment of the present invention, respectively. As can be seen from fig. 8a and 8b, the photoacoustic imaging picture obtained by using the ultrasonic imaging system according to the embodiment of the present invention has high imaging quality.
In an alternative embodiment, the fiber optic ultrasonic sensors are wavelength modulation type sensors or frequency modulation type sensors, each of which has a different operating wavelength, and an external ultrasonic signal is applied to the sensors to cause modulation of the output wavelength (or frequency) thereof.
In another alternative embodiment, the fiber optic ultrasonic sensor further comprises a single polarization type fiber optic sensor;
the optical signal acquisition module further comprises an unbalanced interferometer configured to convert the delay modulated optical signal into an optical intensity signal and output the optical intensity signal to the photodetector.
In another optional embodiment, the fiber optic ultrasonic sensor further comprises a single frequency output type fiber optic sensor;
the optical signal acquisition module further comprises an unbalanced interferometer in combination with a photodetector configured to convert the delay modulated optical signal into an optical intensity signal and output to the photodetector.
In another optional embodiment, the fiber optic ultrasonic sensor further comprises a passive fiber optic resonator configured to output the modulated optical signal;
the optical signal acquisition module further comprises a frequency comb configured to detect frequency information of the modulated optical signal output by the passive optical fiber resonator and output the frequency information to the photodetector.
In another optional embodiment, the fiber optic ultrasonic sensor further comprises a passive fiber optic resonator configured to output the modulated optical signal;
the optical signal acquisition module further comprises a tunable laser configured to detect frequency information of the modulated optical signal output by the passive optical fiber resonator and output the frequency information to the photodetector.
The process and principle of modulating the ultrasonic signal by the optical fiber ultrasonic sensor and the optical signal acquisition module according to the above embodiments of the present invention are similar to those of the above embodiments, and are not described herein again. The embodiment of the invention can be applied to various optical fiber ultrasonic sensors and optical signal acquisition modules, can reduce the manufacturing cost of the photoacoustic imaging system, can realize high-quality imaging pictures, and has wide application prospect.
Another embodiment of the present invention provides a method for performing ultrasound imaging by using the above ultrasound imaging system of the present invention, as shown in fig. 9, the method comprising:
modulating according to an external ultrasonic signal and outputting a plurality of modulated optical signals with preset wavelengths;
outputting a delay modulation optical signal under a preset delay amount based on the modulation optical signal;
and generating a photoacoustic imaging picture according to the delay modulation optical signal.
In a specific example, the external ultrasonic signal is generated by excitation of transient thermal expansion generated by absorption of laser pulses by target tissues, and the sensor module modulates the external ultrasonic signal and outputs a plurality of modulated optical signals with preset wavelengths; the time division multiplexing module outputs a delay modulation optical signal under a preset delay amount based on the modulation optical signal; the optical signal acquisition module generates a photoacoustic imaging picture according to the delay modulation optical signal, the photoacoustic imaging picture obtained by the ultrasonic imaging method of the embodiment of the invention can realize simultaneous signal acquisition of a plurality of sensors in the sensor module through one optical signal acquisition module, electromagnetic crosstalk does not exist among a plurality of optical fiber sensors in the sensor module, parallel modulation and acquisition of the same external ultrasonic signal are realized, the imaging quality of the photoacoustic imaging picture is effectively improved, and the photoacoustic imaging picture has wide application prospect.
It should be noted that, the sequence of the steps of the ultrasound imaging method provided in the embodiment of the present invention may be appropriately adjusted, and the steps may also be increased or decreased according to the circumstances, and any method that can be easily changed by a person skilled in the art within the technical scope disclosed in the present invention should be covered in the protection scope of the present invention, and therefore, the details are not described again.
It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.
Claims (10)
1. An ultrasound imaging system, comprising:
a sensor module configured to modulate an external ultrasonic signal and output a plurality of modulated optical signals of preset wavelengths;
a time division multiplexing module configured to output a delay modulated optical signal under a preset delay amount based on the modulated optical signal;
and the optical signal acquisition module is configured to generate a photoacoustic imaging picture according to the delay modulation optical signal.
2. The system of claim 1, wherein the sensor module comprises fiber optic ultrasonic sensors of different preset wavelengths; wherein the fiber optic ultrasonic sensor comprises:
a laser light source unit configured to emit incident laser light;
an optical fiber connected to the semiconductor laser and configured to modulate and output an external ultrasonic signal based on the incident laser light; and
and the reflection grating cavity mirrors are positioned on the optical fibers in pairs.
3. The system of claim 2, wherein the optical fiber comprises rare earth ions.
4. The system of claim 1, wherein the time-division multiplexing module comprises:
a wavelength division multiplexer: the optical fiber is configured to receive the modulated optical signals with the preset wavelengths and output the modulated optical signals through the same optical fiber line;
a gating switch configured to select a modulated optical signal that satisfies a preselected time threshold in accordance with the preselected time threshold;
a circulator configured to direct the modulated light signal that satisfies the preselected time threshold to the reflective delay unit; and
a reflection delay unit corresponding to the preset wavelength configured to reflect and delay the modulated optical signal corresponding to the preset wavelength, so that the circulator outputs a delayed modulated optical signal.
5. The system of claim 4, wherein the reflective delay unit comprises: narrow-band reflection components and delay optical fibers which are alternately arranged;
the narrow-band reflection component comprises at least one narrow-band reflection piece corresponding to the preset wavelength;
the delay optical fiber assembly comprises a delay optical fiber arranged on one side of the narrow-band reflecting piece far away from the circulator or a delay optical fiber arranged between the adjacent narrow-band reflecting pieces.
6. The system of claim 1, wherein the optical signal acquisition module comprises:
a photoelectric conversion unit configured to output a delay-modulated electrical signal in accordance with the delay-modulated optical signal:
a signal demodulation unit configured to demodulate the delay-modulated electric signal; and
an image processing unit configured to generate a photoacoustic imaging picture from the delay-modulated electrical signal.
7. The system of claim 6, wherein the photoelectric conversion unit comprises:
an amplifier configured to amplify the delay-modulated optical signal;
a photodetector configured to convert the delay-modulated optical signal into the delay-modulated electrical signal;
the frequency conversion unit is configured to carry out frequency conversion processing on the modulated electric signal; and
and the analog-to-digital conversion unit is configured to discretize the modulated electric signal subjected to frequency conversion processing.
8. The system of claim 7, wherein the signal demodulation unit is further configured to recover the discretized frequency-converted modulated electrical signal and output the delayed modulated electrical signal.
9. The system according to any one of claims 1 to 8,
the optical fiber ultrasonic sensor is a wavelength modulation type sensor or a frequency modulation type sensor;
or
The optical fiber ultrasonic sensor also comprises a single polarization type optical fiber sensor;
the optical signal acquisition module further comprises an unbalanced interferometer configured to convert the delay modulation optical signal into an optical intensity signal and output the optical intensity signal to the photodetector;
or
The optical fiber ultrasonic sensor also comprises a single-frequency output type optical fiber sensor;
the optical signal acquisition module also comprises an unbalanced interferometer combined with a photoelectric detector, and is configured to convert the delay modulation optical signal into an optical intensity signal and output the optical intensity signal to the photoelectric detector; or
The fiber-optic ultrasonic sensor further comprises a passive fiber-optic resonant cavity configured to output the modulated optical signal;
the optical signal acquisition module further comprises a frequency comb configured to detect frequency information of the modulated optical signal output by the passive optical fiber optical resonant cavity and output the frequency information to the photodetector;
or
The fiber-optic ultrasonic sensor further comprises a passive fiber-optic resonant cavity configured to output the modulated optical signal;
the optical signal acquisition module further comprises a tunable laser configured to detect frequency information of the modulated optical signal output by the passive optical fiber resonator and output the frequency information to the photodetector.
10. A method of ultrasound imaging using the ultrasound imaging system of any of claims 1 to 9, characterized by:
modulating according to an external ultrasonic signal and outputting a plurality of modulated optical signals with preset wavelengths;
outputting a delay modulation optical signal under a preset delay amount based on the modulation optical signal;
and generating a photoacoustic imaging picture according to the delay modulation optical signal.
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