CN114324183A - Ultraviolet photoacoustic microscopic imaging system with large focal depth and imaging method - Google Patents
Ultraviolet photoacoustic microscopic imaging system with large focal depth and imaging method Download PDFInfo
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- CN114324183A CN114324183A CN202210095807.2A CN202210095807A CN114324183A CN 114324183 A CN114324183 A CN 114324183A CN 202210095807 A CN202210095807 A CN 202210095807A CN 114324183 A CN114324183 A CN 114324183A
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Abstract
The invention discloses an ultraviolet photoacoustic microscopic imaging system with large focal depth and an imaging method, wherein the system comprises a signal acquisition device and an imaging processing terminal, and the signal acquisition device comprises: the device comprises an ultraviolet pulse laser, a polaroid, a light-adjusting slide, a light filter, a photoacoustic lens, a mobile platform, a groove, a medium, an ultrasonic transducer, an amplifier and a data acquisition card. According to the ultraviolet photoacoustic microimaging system with the large focal depth, the photoacoustic exciting light is modulated through the polarizing film and the light adjusting slide to obtain circularly polarized light, the Gaussian light beam is converted into the Bessel-like light beam through the photoacoustic lens and is focused to irradiate a sample, the sample excites photoacoustic waves due to volume expansion caused by light beam absorption and conducts through a medium, the photoacoustic waves conducted through the medium are detected and imaged, so that the optical focusing length is greatly expanded, the photoacoustic exciting light has subcellular-level transverse resolution within a larger focal depth range, and the imaging resolution of a tissue pathology sample is greatly improved.
Description
Technical Field
The invention relates to the technical field of optical microscopic imaging, in particular to an ultraviolet photoacoustic microscopic imaging system with large focal depth and an imaging method.
Background
It is well known that histopathological examination is an important tool in biomedical diagnostics. The conventional histopathological detection process mainly comprises the following steps: taking a piece of pathological tissue, embedding the pathological tissue in a paraffin block, slicing the pathological tissue into slices, staining the pathological tissue with Hematoxylin-eosin (H-E), observing the pathological tissue with a microscope, and finally making pathological diagnosis. However, conventional histopathological tests take a long time, usually 3 to 4 days, and cannot make a diagnosis in a timely manner.
Photoacoustic microscopy is a booming biomedical imaging technique. Photoacoustic imaging can be used to nondestructively observe biological tissues by detecting ultrasonic waves caused by thermo-elastic expansion of the tissues after the short pulse laser irradiates the biological tissues and the tissues absorb the pulse light. Due to the characteristics of photoacoustic imaging, the photoacoustic imaging has the potential application to histopathological imaging, and replaces the traditional observation of hematoxylin-eosin stained tissue sections by a microscope.
Based on the abundant imaging contrast mechanism of biological tissues, the photoacoustic microscopic imaging has great significance in revealing the pathological process of the biological tissues. Photoacoustic imaging has many advantages over histopathological sections, first, in biological tissues, acoustic scattering is over 1000 times lower than optical scattering, making it break through the limitations of optical scattering. At the same time, photoacoustic microscopy is capable of imaging high contrast biological structures from different dimensions. In addition, different molecules absorb different wavelengths, so that abundant optical contrast information can be revealed.
Xueding Wang et al clearly measured the distribution of cerebral vessels of a mouse through a photoacoustic microscope, and detected the structures of the intracranial cerebellum, hippocampus, lateral ventricle and the like of the mouse, thereby obtaining image information of the brain parenchyma lesion of the mouse. The Yang Wang et al can diagnose and evaluate the melanoma in vivo detection by constructing a photoacoustic and ultrasonic bimodal microscope, imaging the tumor-related vascular network and measuring the thickness of the melanoma. However, the conventional photoacoustic pathological microscopic imaging technology has a short focal depth, is not suitable for the histopathological detection of thick samples, and provides a plurality of challenges for clinical medical detection.
A Huazhong university of science and technology team introduces novel optical imaging devices such as an electric control zoom lens and an imaging optical fiber bundle, and multi-scale imaging of a blood microcirculation network is realized by establishing a multi-scale photoacoustic microimaging system with continuously adjustable resolution. A set of reflective large-depth-of-field optical resolution photoacoustic microscopic imaging system is developed by utilizing the diffraction-free transmission characteristic and self-reconstruction property of Bessel beams. However, the photoacoustic imaging technology with large focal depth cannot work in the ultraviolet light wave band, so that the method cannot be applied to the histopathological detection.
In order to improve the optical focusing length, a cone prism or a Nibor-Zernike light field regulation technology and the like are adopted, and a Gaussian beam can be expanded into a Bessel or Bessel-like beam, so that the optical focal depth is improved, and the three-dimensional imaging quality is improved. Although this technique uses a Digital Micromirror Device (DMD) or a Spatial Light Modulator (SLM) to perform phase modulation, the optical focal depth can also be enlarged. However, these devices are often difficult to use for modulating photoacoustic excitation beams in the ultraviolet band.
Optical-resolution photoacoustic microscopy (OR-PAM) is capable of measuring Optical absorption characteristics with micrometer-scale lateral resolution within biological tissues. Although photoacoustic microscopy has been a great deal of development, there are still many drawbacks to this technique. The traditional photoacoustic microscope adopts Gaussian beams, the imaging focal depth is limited to dozens of micrometers, and the requirement of observing a thick tissue sample is difficult to meet. For photoacoustic pathology imaging, a gaussian beam commonly used in OR-PAM can only maintain micron-scale lateral resolution within a limited Depth range due to a short Depth of focus (DoF), while in an out-of-focus region, photoacoustic imaging resolution is rapidly deteriorated, resulting in severe reduction of image quality, and three-dimensional micro-morphological structural features of a thick tissue sample cannot be accurately obtained, thereby affecting the reliability of tissue pathology diagnosis. Therefore, the existing photoacoustic microscopic imaging technology has the problem of low imaging resolution when a sample is imaged.
Disclosure of Invention
The embodiment of the invention provides an ultraviolet photoacoustic microscopic imaging system with large focal depth and an imaging method, aiming at solving the problem of lower imaging resolution when the existing photoacoustic microscopic imaging technology is used for imaging a tissue pathological sample.
In a first aspect, an embodiment of the present invention provides an ultraviolet photoacoustic microscopic imaging system with a large focal depth, where the system includes a signal acquisition device and an imaging processing terminal, where the signal acquisition device includes: the device comprises an ultraviolet pulse laser, a polaroid, a light-adjusting slide, a light filter, a photoacoustic lens, a mobile platform, a groove, a medium, an ultrasonic transducer, an amplifier and a data acquisition card; the polaroid is arranged at the downstream of the ultraviolet pulse laser, the dimming glass sheet is arranged at the downstream of the polaroid, the optical filter is arranged at the downstream of the dimming glass sheet, and the photoacoustic lens is arranged at the downstream of the optical filter; the groove is arranged on the moving platform so as to drive the groove to perform two-dimensional translation through the moving platform; placing a sample in the groove, wherein the medium covers the sample; the light beam output by the photoacoustic lens is focused and irradiates the sample, so that the volume expansion of the sample caused by the absorption of the light beam excites a photoacoustic wave and the photoacoustic wave is conducted through the medium; the light beam output by the photoacoustic lens is a Bessel-like light beam; the ultrasonic transducer is in contact with the medium so as to acquire photoacoustic waves conducted by the medium through the ultrasonic transducer; the ultrasonic transducer is electrically connected with the data acquisition card through the amplifier, the data acquisition card is electrically connected with the imaging processing terminal so as to output a digital photoacoustic signal to the imaging processing terminal, and the imaging processing terminal processes the digital photoacoustic signal acquired by the data acquisition card to obtain an imaging image of the sample.
The ultraviolet photoacoustic microimaging system with the large focal depth is characterized in that the dimming slide is a dimming slide with a phase plate.
The ultraviolet photoacoustic microimaging system with the large focal depth is characterized in that a confocal lens is arranged between the dimming slide and the optical filter, and the confocal lens consists of a confocal first lens and a confocal second lens.
The ultraviolet photoacoustic microscopic imaging system with large focal depth is characterized in that the medium is normal saline, distilled water or deionized water.
The ultraviolet photoacoustic microscopic imaging system with large focal depth is characterized in that the groove is a transparent groove.
The ultraviolet photoacoustic microimaging system with the large focal depth is characterized in that the depth of the groove is 0.2-10 cm.
The ultraviolet photoacoustic microscopic imaging system with large focal depth is characterized in that the groove is a resin groove, a glass groove or a quartz groove.
On the other hand, the embodiment of the invention also provides an ultraviolet photoacoustic microimaging method with a large focal depth, wherein the ultraviolet photoacoustic microimaging method with the large focal depth is applied to the ultraviolet photoacoustic microimaging system with the large focal depth, and the method comprises the following steps:
controlling an ultraviolet pulse laser to output photoacoustic excitation light through an imaging processing terminal;
the photoacoustic excitation light is modulated into linearly polarized light through a polarizing film and is modulated into circularly polarized light through a light adjusting glass sheet; the circularly polarized light is left-handed circularly polarized light or right-handed circularly polarized light;
filtering light outside an ultraviolet band by the circularly polarized light through an optical filter and modulating light energy to obtain a Gaussian beam;
the Gaussian beam is expanded into a Bessel-like beam through the photoacoustic lens and is focused to irradiate on a sample placed in the groove; the volume expansion of the sample caused by the absorption of the light beam excites the photoacoustic wave and the photoacoustic wave is conducted through the medium;
receiving the photoacoustic wave conducted by the medium through an ultrasonic transducer and outputting the photoacoustic wave to the amplifier for amplification to obtain an amplified signal;
the amplified signal is digitized by a data acquisition card to obtain a digitized photoacoustic signal;
and the imaging processing terminal acquires and processes the digital photoacoustic signal to obtain an imaging image of the sample.
The ultraviolet photoacoustic microimaging method with large focal depth is characterized in that the pulse width of photoacoustic excitation light output by the ultraviolet pulse laser is 10-800 nanoseconds.
The ultraviolet photoacoustic microimaging method with large focal depth is characterized in that the wavelength of photoacoustic excitation light output by the ultraviolet pulse laser is 180-350 nanometers.
The embodiment of the invention provides an ultraviolet photoacoustic microscopic imaging system with large focal depth and an imaging method, wherein the system comprises a signal acquisition device and an imaging processing terminal, and the signal acquisition device comprises: the device comprises an ultraviolet pulse laser, a polaroid, a light-adjusting slide, a light filter, a photoacoustic lens, a mobile platform, a groove, a medium, an ultrasonic transducer, an amplifier and a data acquisition card. According to the ultraviolet photoacoustic microimaging system with the large focal depth, the photoacoustic exciting light is modulated through the polarizing film and the light adjusting slide to obtain circularly polarized light, the Gaussian light beam is converted into the Bessel-like light beam through the photoacoustic lens and is focused to irradiate a sample, the sample excites photoacoustic waves due to volume expansion caused by light beam absorption and conducts through a medium, the photoacoustic waves conducted through the medium are detected and imaged, so that the optical focusing length is greatly expanded, the photoacoustic exciting light has subcellular-level transverse resolution within a larger focal depth range, the resolution of imaging the sample is greatly improved, and the imaging quality is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are 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 is a schematic structural diagram of an ultraviolet photoacoustic microscopy imaging system with a large focal depth provided by an embodiment of the present invention;
FIG. 2 is a schematic flow chart of an ultraviolet photoacoustic microimaging method with a large focal depth according to an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating the effect of an ultraviolet photoacoustic microscopy imaging system with a large focal depth provided by an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating the effect of an ultraviolet photoacoustic microscopy imaging system with a large focal depth provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating the effect of an ultraviolet photoacoustic microscopy imaging system with a large focal depth provided by an embodiment of the present invention;
fig. 6 is a schematic effect diagram of an ultraviolet photoacoustic microscopic imaging system with a large focal depth according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.
In this embodiment, please refer to fig. 1, where fig. 1 is a schematic structural diagram of an ultraviolet photoacoustic microscopy imaging system with a large focal depth according to an embodiment of the present invention. As shown in the figure, the embodiment of the present invention provides an ultraviolet photoacoustic microscopic imaging system with a large focal depth, where the system includes a signal acquisition device and an imaging processing terminal 15, where the signal acquisition device includes: the device comprises an ultraviolet pulse laser 1, a polaroid 2, a light-adjusting slide 3, an optical filter 4, a photoacoustic lens 5, a mobile platform 6, a groove 7, a medium 8, an ultrasonic transducer 9, an amplifier 11 and a data acquisition card 12; the polaroid 2 is arranged at the downstream of the ultraviolet pulse laser 1, the light modulation slide 3 is arranged at the downstream of the polaroid 2, the light filter 4 is arranged at the downstream of the light modulation slide 3, and the photoacoustic lens 5 is arranged at the downstream of the light filter 4; the groove 7 is arranged on the moving platform 6, so that the groove 7 is driven by the moving platform 6 to perform two-dimensional translation; a sample 10 is placed in the groove 7, and the medium 8 covers the sample 10; the light beam output by the photoacoustic lens 5 focuses and irradiates the sample 10, so that the volume expansion of the sample 10 caused by the absorption of the light beam excites a photoacoustic wave and is conducted through the medium 8; the light beam output by the photoacoustic lens 5 is a Bessel-like light beam; the ultrasonic transducer 9 is in contact with the medium 8, so that the photoacoustic wave conducted by the medium 8 is acquired through the ultrasonic transducer 9; the ultrasonic transducer 9 is electrically connected with the data acquisition card 12 through the amplifier 11, the data acquisition card 12 is electrically connected with the imaging processing terminal 15 to output a digitized photoacoustic signal to the imaging processing terminal 15, and the imaging processing terminal 15 processes the digitized photoacoustic signal to obtain an imaging image of the sample.
The ultraviolet photoacoustic microscopic imaging system with the large focal depth outputs photoacoustic exciting light in an ultraviolet band by taking an ultraviolet pulse laser 1 as a light source, and then the photoacoustic exciting light is modulated into linearly polarized light through a polarizing film 2 and is modulated into circularly polarized light through a light adjusting glass sheet 3. The light control slide 3 is a light control slide with a phase plate, which can be 1/4 slide, and left circularly polarized light or right circularly polarized light required by the liquid crystal can be obtained after being modulated by the light control slide 3. After the circularly polarized light is reflected by the reflector, light outside the ultraviolet band is filtered by the optical filter 4, and the energy of the light is modulated to obtain a Gaussian beam. Then, the collimated beam is reflected by a mirror after passing through the lens 13 and enters the photoacoustic lens 5. The photoacoustic lens 5 is a liquid crystal phase plate, a corresponding modulation pattern is arranged on the liquid crystal phase plate, and the optical phase distribution of the modulation pattern on the liquid crystal phase plate can be designed based on the expanded Zernike algorithm. The phase plate is not limited to a liquid crystal, and may be made of other materials that can be phase-modulated. The photoacoustic lens 5 can expand incident Gaussian beams into Bessel-like beams, the photoacoustic lens 5 can replace an objective lens to focus the beams and irradiate the beams on the sample 10, the sample is placed in the groove 7, the groove 7 is connected with the moving platform 6, the groove 7 can be driven by the moving platform 6 to perform two-dimensional translation, and therefore the focused Bessel-like beams scan the sample 10 in the X-axis direction and the Y-axis direction. In order to realize two-dimensional scanning of the sample 10, a galvanometer can be used to replace the moving platform 6, and the speed of scanning the sample 10 can be greatly increased through the galvanometer. The sample 10 absorbs the energy of the bessel-like beam, causing thermal volume expansion and emitting a photoacoustic wave. The photoacoustic wave generated by the sample 10 is conducted through the medium 8 and received by the ultrasonic transducer 9, the ultrasonic transducer 9 transmits the received photoacoustic wave to the amplifier 11 for amplification to obtain an amplified signal, the amplified signal is transmitted to the data acquisition card 12 for digitization and storage, and the data acquisition card 12 acquires ultrasonic data once every time the data acquisition card 12 sends a clock signal to the imaging processing terminal 15. The imaging processing terminal 15 receives and processes the digitized photoacoustic signal to obtain an imaging image of the sample 10, thereby accurately acquiring physiological/pathological information of the sample tissue. The imaged image may be a two-dimensional image or a three-dimensional image reconstructed based on the digitized photoacoustic signals.
The technical method in the embodiment provides an ultraviolet light-based microscopic imaging system aiming at a series of challenges faced by tissue pathological diagnosis, and realizes photoacoustic excitation of large optical focal depth through a photoacoustic lens, so as to construct a novel ultraviolet photoacoustic microscope and realize unmarked rapid pathological observation of a three-dimensional microscopic morphological structure of a thick tissue sample. The novel technology has the capabilities of large optical focal depth, subcellular lateral resolution, label-free observation and the like, can realize the micro-scale, section-free and label-free observation of the histopathological sample, and provides novel technical support for clinical medical detection.
Meanwhile, the imaging processing terminal 15 can be electrically connected with the mobile platform 6 and the ultraviolet pulse laser 1; thereby inputting corresponding control parameters to the ultraviolet pulse laser 1 through the imaging processing terminal 15 to control the ultraviolet pulse laser 1 to generate photoacoustic excitation light with specific wavelength and specific pulse width; meanwhile, corresponding movement parameters can be input to the moving platform 6 through the imaging processing terminal, so that the groove 7 is driven by the moving platform 6 to move horizontally. The imaging processing terminal 15 may be a desktop computer, a notebook computer, a tablet computer, or other terminal equipment that can be used for data and image processing.
In a more specific embodiment, a confocal lens 14 is disposed between the light-adjusting glass sheet 3 and the optical filter 4, and the confocal lens 14 is composed of a first lens and a second lens which are confocal. In order to improve the imaging effect, a confocal lens 14 can be arranged between the light adjusting glass slide 3 and the optical filter 4, a 4F optical system formed by the confocal lens 14 expands the circularly polarized light (left circularly polarized light or right circularly polarized light) emitted by the light adjusting glass slide 3, the expanded light beams are transmitted to the optical filter 4 for filtering, the diameter of the light spot of the circularly polarized light can be larger through the expansion, and the effect of filtering treatment of the optical filter 4 is improved. Specifically, the detection light beam output by the light-adjusting glass sheet 3 is not limited to left-handed polarized light, and in the practical application process, right-handed circularly polarized light can be adopted, and the specific rotation direction can be based on the corresponding characteristics of liquid crystal.
In a more specific embodiment, the medium 8 is normal saline, distilled water or deionized water, and in practical use, distilled water is preferably used as the medium 8, and in a most preferred embodiment, deionized water is selected as the medium 8.
In a more specific embodiment, the groove 7 is a transparent groove. Specifically, the depth of the groove 7 is 0.2-10 cm. Wherein, the groove 7 is a resin groove, a glass groove or a quartz groove. Specifically, the groove 7 may be provided as a transparent groove, thereby increasing the light transmittance of the groove 7. The depth of the groove 7 can be reasonably set according to actual use conditions, and the thickness of the medium 8 is smaller than the depth of the groove 7 and is adjusted according to actual conditions. By reasonably setting the thickness of the medium 8, the efficiency of the ultrasonic transducer 9 for receiving the photoacoustic wave can be improved.
Compared with the traditional photoacoustic microscopic imaging technology, the signal acquisition device in the ultraviolet photoacoustic microscopic imaging system with large focal depth has the following characteristics: 1. the conventional photoacoustic pathological microscopic imaging technology has short focal depth, and the liquid crystal phase modulation based on the photoacoustic lens can realize photoacoustic excitation with large optical focal depth. 2. The photoacoustic lens has good transverse resolution (about 0.8 micrometer) in a large depth range, and can clearly observe subcellular structures such as cell nucleus and the like. 3. The large focal depth ultraviolet light sound microscopic imaging technology can carry out histopathological detection on thick samples, has the advantages of integration and miniaturization, and is favorable for the application of the large focal depth ultraviolet light sound microscopic imaging technology in clinical medical diagnosis.
In the embodiment of the present invention, a bessel-like light beam in a photoacoustic lens is analyzed, fig. 3, fig. 4, fig. 5, and fig. 6 are schematic diagrams of the effect of the ultraviolet photoacoustic microimaging system with a large focal depth provided by the embodiment of the present invention, and the distribution situation of the amplitude, the phase, and the intensity of the bessel-like light beam in the photoacoustic lens obtained by the analysis is shown in fig. 3, (a) in fig. 3 is the amplitude distribution situation, (b) in fig. 3 is the phase distribution situation, and (c) in fig. 3 is the intensity distribution situation; the distribution of the optical field in the photoacoustic lens obtained by analysis is shown in fig. 4, the transverse distribution (X-axis direction) curve of the focused optical field of the photoacoustic lens obtained by analysis is shown in fig. 5, and the axial distribution (Z-axis direction) curve of the focused optical field of the photoacoustic lens obtained by analysis is shown in fig. 6. By the phase distribution of the photoacoustic lens, we can calculate the light field distribution of the light beam, as shown in fig. 4. Then, as shown in fig. 5 and 6, it can be known from fig. 5 and 6 that the photoacoustic lens stretches the light beam into a bessel-like light beam, the transverse resolution is 0.85 μm, the diffraction limit is broken, the axial length is about 300 μm, which is 5-6 times that of a gaussian light beam, the quality of the light beam is greatly improved, and the imaging resolution can be greatly improved.
Referring to fig. 2, fig. 2 is a schematic flow chart of a method of ultraviolet photoacoustic microscopy imaging with a large focal depth according to an embodiment of the present invention. The embodiment of the invention also provides an ultraviolet photoacoustic microimaging method with a large focal depth, wherein the ultraviolet photoacoustic microimaging method with the large focal depth is applied to the ultraviolet photoacoustic microimaging system with the large focal depth, as shown in fig. 2, and the method comprises the steps of S110-S170.
S110, controlling an ultraviolet pulse laser to output photoacoustic excitation light through an imaging processing terminal;
specifically, in this embodiment, the imaging processing terminal may control the ultraviolet pulse laser to output the photoacoustic excitation light having a wavelength located in an ultraviolet light band, where the wavelength of the photoacoustic excitation light is 180 nm to 350 nm. The pulse width of the ultraviolet pulse laser can also be controlled through the imaging processing terminal, for example, the ultraviolet pulse laser is controlled to generate photoacoustic excitation light with the pulse width of nanosecond, for example, the pulse width of the photoacoustic excitation light is 10-800 nanoseconds. Different wavelengths and different pulse widths of photoacoustic excitation light can be used for imaging for different tissue samples, for example, a wavelength of 266nm and a pulse width of 200ns (nanoseconds) of photoacoustic excitation light can be used for a specific tissue sample. The wavelength can be changed for different samples, based on the maximum absorption coefficient of the sample and the strongest generated photoacoustic signal.
S120, modulating the photoacoustic excitation light into linearly polarized light through a polarizing film, and modulating the linearly polarized light into circularly polarized light through a light adjusting slide; the circularly polarized light is left-handed circularly polarized light or right-handed circularly polarized light.
The light beams modulated and output by the light adjusting glass sheet can be left-handed circularly polarized light or right-handed circularly polarized light, and the liquid crystal characteristics of the liquid crystal phase plate arranged on the light adjusting glass sheet are used as the standard in the specific application process.
And S130, filtering the light outside the ultraviolet band by the circularly polarized light through an optical filter and modulating light energy to obtain a Gaussian beam.
S140, expanding the Gaussian beam into a Bessel-like beam through a photoacoustic lens, and focusing and irradiating the Bessel-like beam on a sample placed in the groove; the volume expansion of the sample caused by the absorption of the light beam excites the photoacoustic wave and propagates through the medium.
The specific selectable medium is any one of normal saline, distilled water or deionized water.
And S150, receiving the photoacoustic wave conducted by the medium through an ultrasonic transducer, and outputting the photoacoustic wave to the amplifier for amplification to obtain an amplified signal.
And S160, digitizing the amplified signals by a data acquisition card to obtain digitized photoacoustic signals.
And S170, the imaging processing terminal acquires and processes the digital photoacoustic signal to obtain an imaging image of the sample.
The ultraviolet photoacoustic microimaging method with large focal depth in the embodiment is suitable for constructing a photoacoustic lens modulated by an ultraviolet band to obtain an ultraviolet photoacoustic microimaging system, and the technical bottleneck that a Digital Micromirror Device (DMD) or a Spatial Light Modulator (SLM) cannot work in the band is overcome by the technical method. The photoacoustic lens in the imaging system modulates the Gaussian beam into the Bessel-like beam, realizes the focusing of large optical focal depth, has subcellular-level transverse resolution within a larger depth range, and constructs a large-focal-depth ultraviolet light acoustic microscope facing to the great requirement of the clinical medicine of tissue pathology photoacoustic imaging, so that the imaging equipment is miniaturized and simplified, and a novel technical means suitable for pathological observation of thick tissue samples without marks and slices is provided. The large-focal-depth ultraviolet light acoustic microscopic imaging system constructed based on the technical method is suitable for observing a thick tissue sample, can excite the photoacoustic signal of the tissue at a large depth, simultaneously ensures the lateral resolution of a subcellular level, and realizes the 'unmarked and slicing-free' imaging of the three-dimensional microstructure of the tissue sample.
The embodiment of the invention provides an ultraviolet photoacoustic microscopic imaging system with large focal depth and an imaging method, wherein the system comprises a signal acquisition device and an imaging processing terminal, and the signal acquisition device comprises: the device comprises an ultraviolet pulse laser, a polaroid, a light-adjusting slide, a light filter, a photoacoustic lens, a mobile platform, a groove, a medium, an ultrasonic transducer, an amplifier and a data acquisition card. According to the ultraviolet photoacoustic microimaging system with the large focal depth, the photoacoustic exciting light is modulated through the polarizing film and the light adjusting slide to obtain circularly polarized light, the Gaussian light beam is converted into the Bessel-like light beam through the photoacoustic lens and is focused to irradiate a sample, the sample excites photoacoustic waves due to volume expansion caused by light beam absorption and conducts through a medium, the photoacoustic waves conducted through the medium are detected and imaged, so that the optical focusing length is greatly expanded, the photoacoustic exciting light has subcellular-level transverse resolution within a larger focal depth range, the resolution of imaging the sample is greatly improved, and the imaging quality is improved.
While the invention has been described with reference to specific embodiments, the invention is not limited thereto, and various equivalent modifications and substitutions can be easily made by those skilled in the art within the technical scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. The ultraviolet photoacoustic microscopic imaging system with large focal depth is characterized by comprising a signal acquisition device and an imaging processing terminal, wherein the signal acquisition device comprises: the device comprises an ultraviolet pulse laser, a polaroid, a light-adjusting slide, a light filter, a photoacoustic lens, a mobile platform, a groove, a medium, an ultrasonic transducer, an amplifier and a data acquisition card;
the polaroid is arranged at the downstream of the ultraviolet pulse laser, the dimming glass sheet is arranged at the downstream of the polaroid, the optical filter is arranged at the downstream of the dimming glass sheet, and the photoacoustic lens is arranged at the downstream of the optical filter;
the groove is arranged on the moving platform so as to drive the groove to perform two-dimensional translation through the moving platform; placing a sample in the groove, wherein the medium covers the sample;
the light beam output by the photoacoustic lens is focused and irradiates the sample, so that the volume expansion of the sample caused by the absorption of the light beam excites a photoacoustic wave and the photoacoustic wave is conducted through the medium; the light beam output by the photoacoustic lens is a Bessel-like light beam;
the ultrasonic transducer is in contact with the medium so as to acquire photoacoustic waves conducted by the medium through the ultrasonic transducer;
the ultrasonic transducer is electrically connected with the data acquisition card through the amplifier, the data acquisition card is electrically connected with the imaging processing terminal so as to output a digital photoacoustic signal to the imaging processing terminal, and the imaging processing terminal processes the digital photoacoustic signal acquired by the data acquisition card to obtain an imaging image of the sample.
2. The large depth of focus ultraviolet photoacoustic microscopy imaging system of claim 1, wherein the light control slide is a phase-slide light control slide.
3. The ultraviolet photoacoustic microscopy system with large focal depth according to claim 1 or 2, wherein a confocal lens is disposed between the light-adjusting slide and the filter, and the confocal lens is composed of a first lens and a second lens which are confocal.
4. The large depth of focus ultraviolet photoacoustic microscopy imaging system of claim 1, wherein the medium is physiological saline, distilled water, or deionized water.
5. The large depth of focus ultraviolet photoacoustic microscopy imaging system of claim 1, wherein the grooves are transparent grooves.
6. The large depth of focus ultraviolet photoacoustic microscopy imaging system of claim 5, wherein the depth of the grooves is 0.2-10 cm.
7. The large focal depth ultraviolet photoacoustic microscopy imaging system according to claim 5 or 6, wherein the grooves are resin grooves, glass grooves or quartz grooves.
8. A large-focal-depth ultraviolet photoacoustic microimaging method applied to the large-focal-depth ultraviolet photoacoustic microimaging system according to any one of claims 1 to 7, the method comprising:
controlling an ultraviolet pulse laser to output photoacoustic excitation light through an imaging processing terminal;
the photoacoustic excitation light is modulated into linearly polarized light through a polarizing film and is modulated into circularly polarized light through a light adjusting glass sheet; the circularly polarized light is left-handed circularly polarized light or right-handed circularly polarized light;
filtering light outside an ultraviolet band by the circularly polarized light through an optical filter and modulating light energy to obtain a Gaussian beam;
the Gaussian beam is expanded into a Bessel-like beam through the photoacoustic lens and is focused to irradiate on a sample placed in the groove; the volume expansion of the sample caused by the absorption of the light beam excites the photoacoustic wave and the photoacoustic wave is conducted through the medium;
receiving the photoacoustic wave conducted by the medium through an ultrasonic transducer and outputting the photoacoustic wave to the amplifier for amplification to obtain an amplified signal;
the amplified signal is digitized by a data acquisition card to obtain a digitized photoacoustic signal;
and the imaging processing terminal acquires and processes the digital photoacoustic signal to obtain an imaging image of the sample.
9. The ultraviolet photoacoustic microscopy imaging method with large focal depth according to claim 8, wherein the pulse width of the photoacoustic excitation light output by the ultraviolet pulse laser is 10-800 nanoseconds.
10. The ultraviolet photoacoustic microscopy imaging method with large focal depth according to claim 8, wherein the wavelength of the photoacoustic excitation light output by the ultraviolet pulse laser is 180 nm to 350 nm.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116026764A (en) * | 2023-03-30 | 2023-04-28 | 之江实验室 | Photoacoustic microscopic imaging system and method based on self-focusing light beam |
| CN116087111A (en) * | 2023-03-29 | 2023-05-09 | 之江实验室 | Photoacoustic microscopic imaging system and method based on array type frequency field modulated light beam |
| CN116879180A (en) * | 2023-09-08 | 2023-10-13 | 之江实验室 | Photoacoustic microimaging system and method based on radial polarization modulation beam focusing |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116087111A (en) * | 2023-03-29 | 2023-05-09 | 之江实验室 | Photoacoustic microscopic imaging system and method based on array type frequency field modulated light beam |
| CN116026764A (en) * | 2023-03-30 | 2023-04-28 | 之江实验室 | Photoacoustic microscopic imaging system and method based on self-focusing light beam |
| CN116879180A (en) * | 2023-09-08 | 2023-10-13 | 之江实验室 | Photoacoustic microimaging system and method based on radial polarization modulation beam focusing |
| CN116879180B (en) * | 2023-09-08 | 2023-12-01 | 之江实验室 | Photoacoustic microimaging system and method based on radial polarization modulation beam focusing |
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