Laser speckle blood flow imaging system

Abstract

The embodiment of the present application provides a kind of laser speckle blood flow imaging system, including first laser light source;Second laser light source;Optical imaging module;With the image processing module being connected to optical imaging module;First laser light source and optical imaging module are located in the same side of the object to be measured, and the light emitted by first laser light source enters image processing module after scattering through the object to be measured, and first speckle image is formed;Second laser light source and optical imaging module are located in the different side of the object to be measured, and the light emitted by second laser light source enters image processing module after scattering through the object to be measured, and second speckle image is formed.The embodiment of the present application uses first laser light source or uses second laser light source according to the characteristics of the object to be measured, or both first laser light source and second laser light source are used, and then the first speckle image and the second speckle image are comprehensively processed, can adapt to the characteristic difference of various objects to be measured, and improve the signal-to-noise ratio of speckle image.

Description

Technical Field

[0001] This invention relates to the field of laser speckle technology, and more particularly to a laser speckle blood flow imaging system. Background Technology

[0002] Laser speckle imaging is a regional blood flow velocity observation technique that dynamically and non-contactly observes changes in blood flow velocity, vessel diameter, and blood flow in living biological tissues with high spatial and temporal resolution without scanning, obtaining multiple hemodynamic parameters.

[0003] In experiments and clinical settings, the characteristics of various living biological tissues differ greatly. For example, zebrafish have a smooth and relatively transparent surface, and when using an epi-laser source to acquire speckle images, specular reflections can easily occur on the zebrafish's surface, thus affecting the signal-to-noise ratio of the speckle images. In contrast, since blood flow in the mouse brain is located in a deeper layer of the brain, an epi-laser source is more suitable for acquiring speckle images. Summary of the Invention

[0004] This invention provides a laser speckle blood flow imaging system, which aims to solve the problem that the existing epi-laser light source cannot adapt to the large differences in the characteristics of various living biological tissues.

[0005] In a first aspect, a laser speckle blood flow imaging system is provided, comprising:

[0006] First laser source (1);

[0007] Second laser source (2);

[0008] Optical imaging module (3); and

[0009] Image processing module (4) connected to optical imaging module (3);

[0010] The first laser source (1) and the optical imaging module (3) are located on the same side of the object under test. The light emitted by the first laser source (1) is scattered by the object under test and then enters the image processing module (4) through the optical imaging module (3) to form a first speckle image. The second laser source (2) and the optical imaging module (3) are located on opposite sides of the object under test. The light emitted by the second laser source (2) is scattered by the object under test and then enters the image processing module (4) through the optical imaging module (3) to form a second speckle image.

[0011] In this embodiment of the invention, a first laser source and a second laser source are respectively set on both sides of the object under test. The first laser source and the optical imaging module are located on the same side of the object under test, which is an incident imaging method. The second laser source and the optical imaging module are located on opposite sides of the object under test, which is a transmissive imaging method. Depending on the characteristics of the object under test, the first laser source can be used alone to acquire a first speckle image, or the second laser source can be used alone to acquire a second speckle image, or both the first laser source and the second laser source can be used to acquire a first speckle image and the second laser source can be used to acquire a second speckle image. After combining the first speckle image and the second speckle image, the invention can adapt to the differences in characteristics of various objects under test and improve the signal-to-noise ratio of the final speckle image. Attached Figure Description

[0012] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0013] Figure 1 This is a schematic diagram of the structure of the laser speckle blood flow imaging system provided in Embodiment 1 of the present invention;

[0014] Figure 2 This is a schematic diagram of the structure of the first laser source provided in Embodiment 1 of the present invention;

[0015] Figure 3 This is a schematic diagram of the structure of the second laser source provided in Embodiment 1 of the present invention;

[0016] Figure 4 This is a schematic diagram of the incident imaging and transmission imaging provided in Embodiment 1 of the present invention;

[0017] Figure 5 This is another structural schematic diagram of the laser speckle blood flow imaging system provided in Embodiment 1 of the present invention. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar modules or modules having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Rather, embodiments of the present invention include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0019] Laser speckle blood flow imaging is a method for real-time dynamic blood flow observation and video imaging recording in basic life science research and clinical medicine. It is a crucial basis for understanding the pathological or physiological indicators of tissues and organs.

[0020] In this embodiment of the invention, a first laser source and a second laser source are respectively set on both sides of the object under test. The first laser source and the optical imaging module are located on the same side of the object under test, which is an incident imaging method. The second laser source and the optical imaging module are located on opposite sides of the object under test, which is a transmissive imaging method. Depending on the characteristics of the object under test, the first laser source can be used alone to acquire a first speckle image, or the second laser source can be used alone to acquire a second speckle image, or both the first laser source and the second laser source can be used to acquire a first speckle image and the second laser source can be used to acquire a second speckle image. After combining the first speckle image and the second speckle image, the invention can adapt to the differences in characteristics of various objects under test and improve the signal-to-noise ratio of the final speckle image.

[0021] Example 1

[0022] Figure 1 This is a schematic diagram of the structure of the laser speckle blood flow imaging system provided in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the structure of the first laser source provided in Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the structure of the second laser source provided in Embodiment 1 of the present invention. Figure 1 , Figure 2 and Figure 3 As shown, the system includes a first laser source 1, a second laser source 2, an optical imaging module 3, an image processing module 4, and a stage 5. The stage 5 is a transparent flat optical glass. When generating a speckle image, the object under test is placed on the stage 5. In some embodiments, the system does not include the stage 5, which is selected by the operator according to experimental needs.

[0023] The first laser source 1 and the second laser source 2 can be the same single-mode near-infrared laser source module, emitting laser wavelengths within the optical window that can enter living biological tissue, preferably 650nm-1000nm. In this embodiment of the invention, the first laser source 1 includes a first laser 11, a first collimating lens 12, a first homogenizing element 13, and a first beam expander 14. The second laser source 2 includes a second laser 21, a second collimating lens 22, a second homogenizing element 23, and a second beam expander 24.

[0024] The first laser 11 and the second laser 21 are solid-state lasers, semiconductor lasers, or gas lasers, preferably 785nm semiconductor lasers, outputting 785nm single-mode near-infrared laser light. Furthermore, the semiconductor laser includes a temperature control device to ensure that the semiconductor laser operates at a stable temperature, enabling stable laser output.

[0025] The laser beam output from the first laser 11 is a Gaussian beam, which is converted into a flat-top beam after passing through the first homogenizing element 13; the laser beam output from the second laser 21 is also a Gaussian beam, which is also converted into a flat-top beam after passing through the second homogenizing element 23. The energy of the flat-top beam is uniformly distributed and falls onto the object under test. In order to better form a flat-top beam, a first collimating lens 12 is set between the first laser 11 and the first homogenizing element 13, and a second collimating lens 22 is set between the second laser 21 and the second homogenizing element 23. The laser beams output from the first laser 11 and the second laser 21 are shaped into collimated Gaussian beams, and then converted into collimated flat-top beams by the first homogenizing element 13 and the second homogenizing element 23.

[0026] A first beam expander 14 is provided at the exit end of the first homogenizing element 13, and a second beam expander 24 is provided at the exit end of the second homogenizing element 23, so that the collimated flat-top beam is projected onto the stage 5 in a divergent manner, resulting in light spots of different areas projected onto the object under test at different working distances. Appropriate first beam expanders 14 and second beam expanders 24 are selected so that the light spot projected onto the object under test is not smaller than the imaging area of ​​the optical imaging module 3.

[0027] In this embodiment of the invention, the first laser source 1 and the optical imaging module 3 are located on the same side of the object under test, while the second laser source 2 and the optical imaging module 3 are located on opposite sides of the object under test. For spatial height considerations, preferably, the second laser source 2 also includes a reflector 25. Figure 3 As shown, a reflector 25 is placed between the second homogenizing element 23 and the second beam expander 24 to refract the collimated flat-top beam by 90 degrees. The reflector 25 can be a right-angle total internal reflection mirror or a plane reflector placed at a 45-degree angle to the optical axis of the second laser 21.

[0028] The first laser source 1 and the optical imaging module 3 are located on the same side of the object under test, employing incident imaging. The laser beam is uniformly incident on one side of the object, then enters the object, is scattered within it, and exits through the same-side surface of the object before entering the optical imaging module 3. The second laser source 2 and the optical imaging module 3 are located on opposite sides of the object, employing transmission imaging. The laser beam is uniformly incident on one side of the object, then enters the object, is scattered within it, and then transmits through the opposite-side surface of the object before entering the optical imaging module 3. Figure 4 This is a schematic diagram of the incident imaging and transmission imaging provided in Embodiment 1 of the present invention.

[0029] In this embodiment of the invention, the optical axis of the first laser source 1 coincides with or forms an angle with the optical axis of the optical imaging module 3. For example... Figure 1As shown, the first laser source 1 is symmetrically arranged around the optical imaging module 3, and its optical axis coincides with the optical axis of the optical imaging module 3. Alternatively, the first laser source 1 is only arranged on one side of the optical imaging module 3, and its optical axis forms an angle α with the optical axis of the optical imaging module 3.

[0030] In this embodiment of the invention, the second laser source 2 is an independent structure, while the first laser source 1 and the optical imaging module 3 are integrated into one unit. In experiments or clinical settings, operators can choose whether to configure the second laser source 2 based on experimental needs. In another embodiment of the invention, the first laser source 1 and the second laser source 2 are an integrated structure, with the first laser source 1 and the optical imaging module 3 integrated into one unit. The relative positions of the optical axes of the first laser source 1, the second laser source 2, and the optical imaging module 3 are essentially fixed, reducing the need for alignment operations by the operator during experiments.

[0031] Figure 5 This is another structural schematic diagram of the laser speckle blood flow imaging system provided in Embodiment 1 of the present invention. (See diagram below.) Figure 1 and Figure 5 As shown, the optical imaging module 3 is connected to the image processing module 4. The optical imaging module 3 collects the light signal scattered by the sample under test and converts it into an electrical signal. The image processing module 4 processes the electrical signal into a speckle image and / or a blood flow distribution image.

[0032] In this embodiment of the invention, the optical imaging module 3 includes a lens 31, a filter 32, and a photoelectric array sensor 33. The lens 31 can be a zoom lens, a motorized zoom lens, or a manual zoom lens. The lens 31 guides the light signal to the photoelectric array sensor 33, causing the light signal to be imaged on the photosensitive surface of the photoelectric array sensor 33 at a specific magnification. The filter 32 is disposed at the front end of the lens 31. Light output from the first laser source 1 and / or the second laser source 2 and scattered by the object under test can pass through the filter 32, while light of other wavelengths is filtered out, thereby reducing interference from visible and infrared light. The photoelectric array sensor 33 can be a charge-coupled device (CCD) image sensor, a complementary metal-oxide-semiconductor (CMOS) image sensor, or an electron-multiplying CCD (EMCCD) image sensor, etc. The photoelectric array sensor 33 converts the light signal representing the image into an electrical signal representing the image, and then transmits it to the image processing module 4.

[0033] Image processing module 4 receives an electrical signal representing an image and generates a speckle image. Further, based on a spatial contrast imaging method, the speckle image is converted into a blood flow distribution image.

[0034] In experiments or clinical settings, operators can use either the first laser source 1 or the second laser source 2 alone, depending on the characteristics of the object under test. The laser beam output from the first laser source 1, after being scattered by the object under test, passes through the optical imaging module 3 and enters the image processing module 4 to form a first speckle image. The image processing module 4 processes only the first speckle image. Similarly, the laser beam output from the second laser source 2, after being scattered by the object under test, passes through the optical imaging module 3 and enters the image processing module 4 to form a second speckle image. The image processing module 4 processes only the second speckle image. If the characteristics of the object under test are complex, operators can also use both the first laser source 1 and the second laser source 2 simultaneously. The first laser source 1 and the second laser source 2 output laser beams in a time-division manner, forming the first and second speckle images in the image processing module 4 in a time-division manner. The image processing module 4 then comprehensively processes both the first and second speckle images to obtain the final speckle image. This laser speckle blood flow imaging system of the present invention can adapt to the characteristics of various living biological tissues, covers multiple experimental scenarios, and improves the signal-to-noise ratio of the final speckle image.

[0035] For example, zebrafish have smooth and relatively transparent surfaces. When acquiring speckle images, using an incident laser source 1 can easily cause specular reflection on the zebrafish's surface, affecting the signal-to-noise ratio of the speckle image. Using a transmission laser source 2 is more suitable. Similarly, in mice, blood flow is located deep within the brain. When acquiring speckle images, using a transmission laser source 2 makes it difficult to penetrate, resulting in a weak useful signal and a low signal-to-noise ratio. In this case, using an incident laser source 1 is more suitable. For complex living biological tissues, speckle images can be acquired sequentially using the first laser source 1 and the second laser source 2, and then compared and analyzed to obtain the final speckle image.

[0036] In this embodiment of the invention, a first laser source and a second laser source are respectively set on both sides of the object under test. The first laser source and the optical imaging module are located on the same side of the object under test, which is an incident imaging method. The second laser source and the optical imaging module are located on opposite sides of the object under test, which is a transmissive imaging method. Depending on the characteristics of the object under test, the first laser source can be used alone to acquire a first speckle image, or the second laser source can be used alone to acquire a second speckle image, or both the first laser source and the second laser source can be used to acquire a first speckle image and the second laser source can be used to acquire a second speckle image. After combining the first speckle image and the second speckle image, the invention can adapt to the differences in characteristics of various objects under test and improve the signal-to-noise ratio of the final speckle image.

[0037] Example 2

[0038] In this embodiment of the invention, the components that are the same as those in Embodiment 1 are referred to by the same reference numerals as those in Embodiment 1, and include all the features described in Embodiment 1, which will not be repeated here.

[0039] like Figure 2 , Figure 3 and Figure 5 As shown, the first laser source 1 also includes a first linear polarizer 15, the second laser source 2 also includes a second linear polarizer 26, and the optical imaging module 3 also includes a third linear polarizer 34.

[0040] A first linear polarizer 15 is positioned between a first homogenizing element 13 and a first beam expander 14, and a second linear polarizer 26 is positioned between a reflector 25 and a second beam expander 24. Both the first linear polarizer 15 and the second linear polarizer 26 are vertical / horizontal linear polarizing filters, filtering the laser beam into vertical / horizontal linearly polarized laser light. The first laser source 1 outputs a diverging vertical / horizontal linearly polarized laser beam, uniformly illuminating the object under test; the second laser source 2 outputs a diverging vertical / horizontal linearly polarized laser beam, uniformly illuminating the object under test. A third linear polarizer 34 is positioned between a lens 31 and a filter 32, and is a horizontal / vertical linear polarizing filter. If the first linear polarizer 15 and the second linear polarizer 26 are both vertical linear polarizing filters, and the third linear polarizer 34 is a horizontal linear polarizing filter, only horizontally polarized light signals are allowed to pass through; if the first linear polarizer 15 and the second linear polarizer 26 are both horizontal linear polarizing filters, and the third linear polarizer 34 is a vertical linear polarizing filter, only vertically polarized light signals are allowed to pass through.

[0041] When a linearly polarized laser beam enters the object under test, it undergoes multiple scatterings within the object, altering its original single polarization characteristic. The light signals emitted or transmitted from the object will contain multiple polarization characteristics; these are the useful signals. However, light signals reflected only from the surface of the object (without entering the object and undergoing scattering), or light signals reflected only from or transmitted only through the stage 5 without illuminating the object, retain their original single polarization characteristic and are considered noise signals. The third linear polarizer 34 in the optical imaging module 3 allows only a portion of the useful signal to pass through while filtering out noise signals. For example, if the first laser source 1 outputs a vertically polarized laser beam that is uniformly incident on the object under test, it undergoes multiple scatterings within the object. The light signals emitted from the object include vertically polarized, horizontally polarized, and other angularly polarized states. Noise signals are all vertically polarized. The optical imaging module 3 only allows the horizontally polarized state of the useful signal to pass through, filtering out other polarization characteristics. This reduces noise and improves the signal-to-noise ratio of the acquired speckle image.

[0042] In this embodiment of the invention, a first laser source and a second laser source are respectively set on both sides of the object under test. The first laser source and the optical imaging module are located on the same side of the object under test, which is an incident imaging method. The second laser source and the optical imaging module are located on opposite sides of the object under test, which is a transmissive imaging method. Depending on the characteristics of the object under test, the first laser source can be used alone to acquire a first speckle image, or the second laser source can be used alone to acquire a second speckle image, or both the first laser source and the second laser source can be used to acquire a first speckle image and the second laser source can be used to acquire a second speckle image. After combining the first speckle image and the second speckle image, the invention can adapt to the differences in characteristics of various objects under test and improve the signal-to-noise ratio of the final speckle image.

[0043] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A laser speckle blood flow imaging system, characterized in that, include: First laser source (1); Second laser source (2); Optical imaging module (3); and An image processing module (4) connected to the optical imaging module (3); The first laser source (1) and the optical imaging module (3) are located on the same side of the object under test. The light emitted by the first laser source (1) enters the object under test, is scattered by the object under test, and then enters the image processing module (4) through the optical imaging module (3) to form a first speckle image for real-time dynamic blood flow observation. The second laser source (2) and the optical imaging module (3) are located on opposite sides of the object under test. The light emitted by the second laser source (2) enters the object under test, is scattered by the object under test, and then enters the image processing module (4) through the optical imaging module (3) to form a second speckle image for real-time dynamic blood flow observation. The laser speckle blood flow imaging system can use the first laser source (1) and the second laser source (2) to sequentially acquire speckle images and perform comparative analysis.

2. The system according to claim 1, characterized in that, The first laser source (1) includes a first laser (11), a first collimating lens (12), a first homogenizing element (13), and a first beam expander (14); the second laser source (2) includes a second laser (21), a second collimating lens (22), a second homogenizing element (23), and a second beam expander (24).

3. The system according to claim 2, characterized in that, The second laser source (2) also includes a reflector (25).

4. The system according to claim 1, characterized in that, The optical imaging module (3) includes a lens (31), a filter (32), and a photoelectric array sensor (33).

5. The system according to claim 1, characterized in that, The optical axis of the first laser source (1) coincides with or forms an angle with the optical axis of the optical imaging module (3).

6. The system according to any one of claims 1-5, characterized in that, The first laser source (1) further includes a first linear polarizer (15), the second laser source (2) further includes a second linear polarizer (26), and the optical imaging module (3) further includes a third linear polarizer (34).

7. The system according to claim 1, characterized in that, It also includes a stage (5), with the first laser light source (1) and the second laser light source (2) located on opposite sides of the stage (5).

8. The system according to claim 7, characterized in that, The second laser source (2) is an independent structure.

9. The system according to claim 7, characterized in that, The first laser source (1) and the second laser source (2) are an integral structure.

10. The system according to claim 1, characterized in that, The image processing module (4) performs integrated processing on the first speckle image and the second speckle image.

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