A handheld fluorescence endoscopy imaging device and method based on coaxial optical path

Abstract

The present invention discloses a handheld fluorescent endoscopic imaging device and method based on a coaxial optical path, which relates to the technical field of optical imaging, and comprises a light homogenizing mechanism, a light modulating mechanism, a beam splitter prism, a light transmitting mechanism, a color camera and a near-infrared camera. The excitation light emitted by the light homogenizing mechanism enters the beam splitter prism through the light modulating mechanism, and the excitation light of a set wavelength band enters the light transmitting mechanism after passing through the beam splitter prism to excite the fluorescent signal of human tissue, and the mixed white light signal and fluorescent signal enter the beam splitter prism through the light transmitting mechanism to perform light separation, the white light signal enters the color camera to obtain a color image, and the fluorescent signal enters the near-infrared camera to obtain a fluorescent image; the handheld fluorescent endoscopic imaging device and method not only reduce the difficulty of the assembly process and image alignment, but also can easily realize the pixel-level fusion of the fluorescent image and the color image; in addition, the device as a whole is in a handheld and portable form, occupies a small space, is not restricted by the medical environment, and improves the application scope and flexibility.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a handheld fluorescent endoscopy imaging device and method based on a coaxial optical path. Background Art

[0002] Digestive system tumors are one of the most common tumors in the world. Early detection, early treatment, and improving the diagnosis level of early cancer have far-reaching significance for improving patient survival rates and reducing socioeconomic burdens. Current international studies have shown that endoscopic examination is the most effective way to detect digestive system tumors, among which fluorescence endoscopy is one of the latest endoscopic fluorescence imaging technologies. Its working principle is to use the specificity of fluorescent dyes and their affinity to cancer cells or lesions. After being excited by an excitation light source, the lesion area emits a fluorescence signal of a specific wavelength, helping doctors to observe and diagnose more accurately. With the continuous advancement and innovation of technology, fluorescence endoscopy has gradually become an important tool for clinical diagnosis and is widely used in the diagnosis of tumors, inflammatory diseases, and infectious diseases in the digestive tract, respiratory tract, urinary tract, and other parts.

[0003] However, in the current fluorescence endoscope system, the excitation light path and the imaging light path are designed to be independent of each other or even placed side by side, resulting in the excitation light field of view and the imaging field of view only overlapping within a specific working distance range, which greatly limits the effective imaging field of view range; at the same time, in the imaging light path, although the white light signal and the fluorescence signal share the objective lens and the dichroic prism, in the final imaging, the white light path and the fluorescence light path are each imaged through the focusing lens in front of the corresponding camera. Such an optical path system will cause large deviations in the field of view positioning of the color image and the fluorescence image due to differences in the focusing lenses and installation errors, which increases the difficulty of the installation process and later image processing, and it is difficult to ensure a high degree of fusion of the white light image and the fluorescence image, which directly affects the doctor's accurate judgment of the lesion location.

[0004] In addition, the current fluorescent endoscope system uses many optical components, is large in size, and has a complex structure. It is mostly presented in the form of a chassis, which takes up space in the operating room and brings inconvenience to medical staff. Summary of the invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a handheld fluorescent endoscopic imaging device and method based on a coaxial optical path, which not only reduces the difficulty of the assembly process and image alignment, but also can easily realize the pixel-level fusion of fluorescent images and color images.

[0006] The present invention proposes a handheld fluorescent endoscopic imaging device and method based on a coaxial optical path, which include a light homogenizing mechanism, a light modulating mechanism, a beam splitter prism, a light transmitting mechanism, a color camera and a near-infrared camera. The excitation light emitted by the light homogenizing mechanism enters the beam splitter prism through the light modulating mechanism, and the excitation light of a set wavelength band enters the light transmitting mechanism after passing through the beam splitter prism to excite the fluorescent signal of human tissue. The mixed white light signal and fluorescent signal enter the beam splitter prism through the light transmitting mechanism for light separation, the white light signal enters the color camera to obtain a color image, and the fluorescent signal enters the near-infrared camera to obtain a fluorescent image.

[0007] Furthermore, the beam splitter prism is formed by gluing three prisms, and has two gluing surfaces, each of which is coated with a film layer so that light of a set wavelength is transmitted and light of other wavelength bands is reflected.

[0008] Furthermore, the first of the two bonding surfaces is coated with a film layer to make the white light and excitation light in the 400-800nm ​​band highly transparent, with a transmittance greater than 99%, and the fluorescence in the 830-1000nm band highly reflective, with a reflectivity greater than 99%, and the second bonding surface is coated with a film layer to make the white light in the 400-700nm band highly reflective, with a reflectivity greater than 95%, and the excitation light in the 750-800nm ​​band highly transparent, with a transmittance greater than 99.5%.

[0009] Furthermore, the three prisms are respectively a first prism, a second prism and a third prism, the first prism and the second prism are connected via a first gluing surface, and the second prism and the third prism are connected via a second gluing surface;

[0010] The white light signal and the fluorescence signal enter the first prism, pass through the first bonding surface, the fluorescence signal in the 830-1000nm band is reflected into the near-infrared camera, the light signal in the 400-800nm ​​band is transmitted into the second prism, pass through the second bonding surface, the white light signal in the 400-700nm band is reflected into the color camera, and the excitation light in the 750-800nm ​​band is transmitted into the third prism.

[0011] Furthermore, according to the transmission direction of the white light signal and the fluorescent signal, an anti-reflection film is arranged at the incident end of the first prism 31, and has a transmittance greater than 99.5% for light in the 400-1000nm band; a dichroic film is arranged at the output end of the first prism 31, which has high transmittance for fluorescence in the 830-1000nm band, with a transmittance greater than 99.8%, and high reflection for white light and excitation light in the 400-800nm ​​band, with a reflectivity greater than 98%; a dichroic film is arranged at the output end of the second prism 32, which has high transmittance for white light in the 400-700nm band, with a transmittance greater than 99%, and high reflection for excitation light in the 750-800nm ​​band, with a reflectivity greater than 98%; an anti-reflection film is arranged at the output end of the third prism 33, which has high transmittance for excitation light in the 750-800nm ​​band, with a transmittance greater than 99.5%.

[0012] Furthermore, the light homogenizing mechanism includes a light source assembly, a first collimating lens, a first adjustable aperture, a focusing lens, a second adjustable aperture, and a second collimating lens. The excitation light emitted by the light source assembly passes through the first collimating lens, the first adjustable aperture, the focusing lens, the second adjustable aperture, and the second collimating lens in sequence before entering the light homogenizing mechanism.

[0013] Furthermore, the dimming mechanism is a digital micromirror device (DMD), and the digital micromirror device (DMD) has three states, namely, deflection of +12°, no deflection, and deflection of -12°.

[0014] Furthermore, the light transmission mechanism includes a telephoto lens, a magnifying objective lens, a fiber optic probe, an imaging fiber and a wide-field imaging objective lens group, one end of the imaging fiber is connected to the fiber optic probe, and the other end is connected to the wide-field imaging objective lens group, the imaging fiber is arranged at the front end of the magnifying objective lens, and the wide-field imaging objective lens group acquires white light signals and fluorescence signals;

[0015] The mixed white light signal and fluorescent signal sequentially pass through the imaging optical fiber, the optical fiber probe, the magnifying objective lens, and the telephoto lens and enter the beam splitter prism for light separation;

[0016] Furthermore, the imaging input end of the color camera is provided with a first filter, and the imaging input end of the near-infrared camera is provided with a second filter.

[0017] An imaging method of a handheld fluorescent endoscopic imaging device based on a coaxial optical path comprises the following steps:

[0018] The excitation light emitted by the light homogenizing mechanism is incident on the digital micro-mirror device DMD at an angle of 24° through the TIR prism of the light modulating mechanism. The digital micro-mirror device DMD allows the excitation light to vertically pass through the TIR prism and be incident on the beam splitter prism.

[0019] The excitation light of the set wavelength passes through the beam splitter prism and reaches the telephoto lens of the light transmission mechanism to become parallel light;

[0020] The parallel light enters the wide-field imaging objective lens group through the light transmission mechanism to stimulate the fluorescence signal of human tissue;

[0021] The mixed white light signal and fluorescent signal enter the beam splitter prism through the light transmission mechanism for light separation;

[0022] The white light signal enters the color camera to obtain a color image, and the fluorescence signal enters the near-infrared camera to obtain a fluorescence image.

[0023] The advantages of the handheld fluorescence endoscopic imaging device and method based on the coaxial optical path provided by the present invention are: the coaxial design of the excitation optical path and the imaging optical path is adopted to achieve a high degree of overlap between the excitation light field of view and the imaging field of view, and expand the effective imaging field of view range; through the optimization design of the beam splitter prism, not only the difficulty of the assembly process and image alignment is reduced, but also the pixel-level fusion of the fluorescence image and the color image can be easily realized; this embodiment adopts a highly integrated design, the whole is a handheld portable form, occupies a small space, is not restricted by the medical environment, and greatly improves the scope of application and flexibility. In addition, this embodiment proposes to use a digital micro-mirror device DMD22 to project a specific non-uniformly distributed pattern to compensate for the non-uniformity in the original light spot, so as to obtain a highly uniform excitation light spot and improve the quality of fluorescence imaging; at the same time, the device has a high transmittance to fluorescence through a special film layer (a film layer set on the beam splitter prism, the first filter and the second filter), and the comprehensive transmittance is greater than 90%, which can be used for spontaneous fluorescence imaging of some tissues without the need to inject fluorescent contrast agents, simplifying the surgical process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the present invention;

[0025] Figure 2 Schematic diagram of the structure of the beam splitter prism;

[0026] Figure 3 It is a structural schematic diagram of a digital micromirror device DMD;

[0027] Among them, 1-light homogenizing mechanism, 2-light adjusting mechanism, 3-beam splitting prism, 4-light transmitting mechanism, 5-color camera, 6-near infrared camera, 7-first filter, 8-second filter, 9-light absorber, 11-light source assembly, 12-first collimating lens, 13-first adjustable aperture, 14-focusing lens, 15-second adjustable aperture, 16-second collimating lens, 21-TIR prism, 22-digital micromirror device DMD, 31-first prism, 32-second prism, 33-third prism, 34-first gluing surface, 35-second gluing surface, 41-telephoto lens, 42-magnifying objective lens, 43-optical fiber probe, 44-imaging optical fiber, 45-wide field of view imaging objective lens group. DETAILED DESCRIPTION

[0028] Below, the technical solution of the present invention is described in detail through specific embodiments. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific implementation disclosed below.

[0029] like Figures 1 to 3 As shown, a handheld fluorescence endoscopic imaging device based on a coaxial optical path proposed in the present invention comprises a light homogenizing mechanism 1, a light modulating mechanism 2, a beam splitter prism 3, a light transmitting mechanism 4, a color camera 5 and a near-infrared camera 6. The excitation light emitted by the light homogenizing mechanism 1 enters the beam splitter prism 3 through the light modulating mechanism 2, and the excitation light of a set wavelength band passes through the beam splitter prism 3 and enters the light transmitting mechanism 4 to excite the fluorescence signal of human tissue. The mixed white light signal and the fluorescence signal enter the beam splitter prism 3 through the light transmitting mechanism 4 for light separation, the white light signal enters the color camera 5 to obtain a color image, and the fluorescence signal enters the near-infrared camera 6 to obtain a fluorescence image.

[0030] By setting the dimming mechanism 2 and the dichroic prism 3, the co-optical axis design of the excitation light path and the imaging light path is realized, the excitation light field of view and the imaging field of view are highly overlapped, and the effective imaging field of view range is expanded; at the same time, the dichroic prism 3 is optimized to avoid the large positioning deviation of the field of view of the color image and the fluorescent image, reduce the difficulty of the installation process and image alignment, and can easily achieve pixel-level fusion of the two images; and this embodiment adopts a highly integrated design internally, and the whole is in a handheld and portable form, occupies a small space, is not restricted by the medical environment, and greatly improves the scope of application and flexibility.

[0031] As a preferred solution, the light homogenizing mechanism 1 includes a light source assembly 11, a first collimating lens 12, a first adjustable aperture 13, a focusing lens 14, a second adjustable aperture 15, and a second collimating lens 16. The excitation light emitted by the light source assembly 11 sequentially passes through the first collimating lens 12, the first adjustable aperture 13, the focusing lens 14, the second adjustable aperture 15, and the second collimating lens 16 before entering the dimming mechanism 2. The dimming mechanism 2 is a digital micromirror device DMD22, which has three states, namely, deflection +12°, no deflection, and deflection -12°.

[0032] In the excitation light path, the excitation light emitted by the light homogenizing mechanism 1 is obliquely incident on the digital micro-mirror device DMD22 at an angle of 24 degrees through the TIR prism 21. The digital micro-mirror device DMD22 allows the reflected light to pass vertically through the TIR prism 21 and be incident on the beam splitter prism 3. The beam splitter prism 3 is coated with a film layer that is selective for the wavelength of the incident light. The selected light passes through the beam splitter prism 3 and reaches the light transmission mechanism 4 to become parallel light, thereby realizing the co-optical axis design of the excitation light path and the imaging light path.

[0033] The digital micromirror device DMD22 is composed of a micromirror array, each micromirror has three states, deflected by +12°, not deflected, and deflected by -12°. When a signal "1" is given to the micromirror, it is deflected by 12°, and the reflected light enters the dichroic prism 3, eventually forming a bright pixel. When a signal "0" is given to the micromirror, it is deflected by -12°, and the reflected light beam cannot enter the dichroic prism 3, but is absorbed by the light absorber 9, so it finally presents a dark pixel. The binary "1" and "0" states of the control signal correspond to the "ON" and "OFF" states of the micromirror, respectively.

[0034] Although the excitation light source obtains a relatively uniform light spot through the homogenization system, it is difficult to ensure the uniformity of the light spot finally incident on the core of the imaging optical fiber 44 due to the existence of installation errors. Generally, the light intensity at the edge is lower than that in the central area and presents a Gaussian distribution. In this embodiment, a digital micromirror device DMD22 is used to project a specific non-uniformly distributed pattern to compensate for the non-uniformity in the original light spot, thereby obtaining a highly uniform excitation light spot and improving the quality of fluorescence imaging.

[0035] As a preferred solution, the dichroic prism 3 is formed by gluing three prisms, and has two gluing surfaces, each of which is coated with a film layer to transmit light of a set wavelength and reflect light in other bands, that is, the first gluing surface 34 of the two gluing surfaces is coated with a film layer to make white light and excitation light in the 400-800nm ​​band highly transparent, with a transmittance greater than 99%, and highly reflective to fluorescence in the 830-1000nm band, with a reflectivity greater than 99%, and the second gluing surface 35 is coated with a film layer to make white light in the 400-700nm band highly reflective, with a reflectivity greater than 95%, and highly transparent to excitation light in the 750-800nm ​​band, with a transmittance greater than 99.5%; while the transmittance of ordinary lenses to visible light and near-infrared light in the 400-1000nm band is usually about 90%, and the reflectivity is less than 10%. Therefore, compared with ordinary lenses, the dichroic prism 3 of this embodiment has higher transmittance and higher reflectivity.

[0036] The three prisms are respectively a first prism 31, a second prism 32 and a third prism 33. The first prism 31 and the second prism 32 are connected via a first bonding surface 34, and the second prism 32 and the third prism 33 are connected via a second bonding surface 35. According to the transmission direction of the white light signal and the fluorescent signal, an anti-reflection film is arranged at the incident end of the first prism 31, which has a high transmittance of light in the 400-1000nm band, and the transmittance is greater than 99.5%. A spectroscopic film is arranged at the exit end of the first prism 31, which has a high transmittance of light in the 830-1000nm band. -1000nm band fluorescence is highly transparent, with a transmittance greater than 99.8%, and is highly reflective to white light and excitation light in the 400-800nm ​​band, with a reflectivity greater than 98%. The output end of the second prism 32 is provided with a dichroic film, which is highly transparent to white light in the 400-700nm band, with a transmittance greater than 99%, and is highly reflective to excitation light in the 750-800nm ​​band, with a reflectivity greater than 98%. The output end of the third prism 33 is provided with an anti-reflection film, which is highly transparent to the excitation light in the 750-800nm ​​band, with a transmittance greater than 99.5%.

[0037] The white light signal and the fluorescent signal enter the first prism 31, pass through the first bonding surface 34, the fluorescent signal in the 830-1000nm band is reflected and enters the near-infrared camera 6, the light signal in the 400-800nm ​​band is transmitted and enters the second prism 32, passes through the second bonding surface 35, the white light signal in the 400-700nm band is reflected and enters the color camera 5, and the excitation light in the 750-800nm ​​band is transmitted and enters the third prism 33. In addition, according to the reversibility of light, the excitation light source from the digital micro-mirror device DMD22 can pass through the second bonding surface 35 and the first bonding surface 34, so the beam splitter prism 3 not only realizes the coaxiality of the excitation light path and the imaging light path, but also avoids the large deviation of the field positioning of the color image and the fluorescent image, and the two images (color image and fluorescent image) can be easily fused at the pixel level during post-processing.

[0038] As a preferred solution, the light transmission mechanism 4 includes a telephoto lens 41, a magnifying objective lens 42, a fiber optic probe 43, an imaging fiber 44 and a wide-field imaging objective lens group 45. One end of the imaging fiber optic 44 is connected to the fiber optic probe 43, and the other end is connected to the wide-field imaging objective lens group 45. The imaging fiber optic 44 is arranged at the front end of the magnifying objective lens 42, and the wide-field imaging objective lens group 45 obtains the white light signal and the fluorescence signal; the mixed white light signal and the fluorescence signal enter the beam splitter prism 3 through the imaging fiber optic 44, the fiber optic probe 43, the magnifying objective lens 42 and the telephoto lens 41 in sequence for light separation.

[0039] In the imaging optical path, one end of the imaging optical fiber 44 is arranged at the rear focal plane of the magnifying objective lens 42 through the optical fiber probe 43, and the other end enters the human body cavity through the biopsy channel of the ordinary endoscope. The excitation light excites the tissue in the human body through the wide-field imaging objective lens group 45 at the head end of the imaging optical fiber 44, and excites the fluorescence signal of the tissue. The mixed white light signal and the fluorescence signal are collected by the imaging optical fiber 44, and become parallel light after passing through the magnifying objective lens 42. In this embodiment, a telephoto lens 41 with a focusing effect is placed before the beam splitter prism 3, and the white light path and the fluorescence path share a telephoto lens 41. The parallel light carrying the white light and the fluorescence signal passes through the telephoto lens 41 and the beam splitter prism 3 in turn, and is finally focused and imaged on the color camera 5 and the near-infrared camera 6 respectively. Since the white light path and the fluorescence path share the telephoto lens 41, the phenomenon of large field positioning deviation of the color image and the fluorescence image caused by the lens itself and assembly errors is avoided, thereby ensuring that the two images can be easily fused at the pixel level after processing.

[0040] As a preferred solution, the imaging incident end of the color camera 5 is provided with a first filter 7 for filtering out stray light outside the 400-700nm band, and the imaging incident end of the near-infrared camera 6 is provided with a second filter 8 for filtering out stray light other than fluorescence.

[0041] As an embodiment

[0042] Excitation light path

[0043] The light source component 11 uses a fiber-coupled laser in the near-infrared band, which can emit 785nm laser, and the laser bandwidth is relatively narrow, with a bandwidth of ±3nm. Compared with ordinary wide-spectrum light sources, the laser has a higher fluorescence excitation efficiency. The light source component 11 is independent of the fluorescence endoscopy imaging device and is connected to the device through a flexible optical fiber, which reduces the impact of the light source heating on the imaging device. The light source component 11 is a divergent light source with a numerical aperture NA=0.22. It can be regarded as a point light source. After passing through the light homogenizing mechanism 1 (first collimating lens 12, first adjustable aperture 13, focusing lens 14, second adjustable aperture 15, second collimating lens 16), it becomes a parallel light of excitation light with uniform brightness.

[0044] The TIR prism 21 utilizes the total reflection principle of light, and changes the propagation path of light through the reflection of light to meet the special incident angle (24°) of the digital micro-mirror device DMD22, and at the same time, it can make the optical path more compact, and the light beam is totally reflected inside the TIR prism 21, and the loss of light beam energy is very small. In order to construct a handheld overall structure, the incident light is obliquely incident on the digital micro-mirror device DMD22 through the TIR prism 21 at an angle of 24°, and the reflected light vertically passes through the TIR prism 21 and is incident on the beam splitter prism 3.

[0045] The digital micro-mirror device DMD22 adopts a new type of optical device launched by Texas Instruments, USA. The digital micro-mirror device DMD22 has many micro-mirrors arranged in an array on the chip. These mirrors have two states, "ON" and "OFF". When the micro-mirror is in the "ON" state, the incident light beam can be reflected to the subsequent light transmission mechanism 4. When the micro-mirror is in the "OFF" state, the angle of the micro-mirror changes, and the light beam incident from the same direction cannot enter the subsequent light transmission mechanism 4. The control circuit can switch any micro-mirror between these two states by controlling the voltage, and the micro-mirror deflection speed is very fast, which can reach 22kHz at the fastest. The digital micro-mirror device DMD22 selected in this embodiment is the DLP LightCrafter6500 of Texas Instruments, with a resolution of up to 1920×1080, more than 2 million micro-mirrors, a micro-mirror spacing of 7.56um, and a micro-mirror deflection angle of ±12°. In this embodiment, the digital micromirror device DMD22 serves as the core device of the excitation light path and plays the role of reflecting the light beam. Therefore, all micromirrors are in the "ON" state. However, due to the inherent properties of the Gaussian beam and assembly errors, it is difficult to ensure the uniformity of the light spot finally incident on the core of the imaging optical fiber. Generally, the light intensity at the edge is lower than that in the central area, showing a Gaussian distribution. In the present invention, the digital micromirror device DMD22 is used to project a specific non-uniformly distributed pattern to compensate for the non-uniformity in the original light spot, thereby obtaining a highly uniform excitation light spot and improving the quality of fluorescence imaging.

[0046] Imaging optical path

[0047] The imaging optical path includes a beam splitter prism 3, a light transmission mechanism 4, a color camera 5, a near-infrared camera 6, a first filter 7, and a second filter 8. The beam splitter prism 3 is composed of three prisms bonded together, with an air layer of 0.005mm-0.01mm thickness left between the bonded surfaces. Each surface of the three prisms is coated with a special film layer, which allows light of a specific wavelength to be transmitted and light of other wavelengths to be reflected, thereby separating the fluorescent signal, the white light signal, and the excitation light. The magnification of the magnifying lens 42 is 10X or 20X, and is used in conjunction with the telephoto lens 41. The magnifying lens 42 generally selects a plan-field apochromatic lens, which can better correct wide-spectrum chromatic aberration and improve imaging quality. The near-infrared camera 6 uses a near-infrared enhanced scientific research camera, whose sensor chip has a high quantum efficiency in the near-infrared band, especially in the 830-1000nm band, and the quantum efficiency can reach 40%. The quantum efficiency of ordinary non-near-infrared enhanced scientific research cameras in the 830-1000nm band is only 20%. Therefore, the near-infrared enhanced scientific research camera can collect weak fluorescence signals. A first infrared blocking filter 7 is provided in front of the color camera 5 to cut off the transmission above 700nm and eliminate the interference of the excitation light on the imaging of the white light signal. The color camera 5 used in this embodiment has the same pixel size and number of pixels as the near-infrared camera 6, which reduces the complexity of the software during the later image fusion and is conducive to the real-time and accurate fusion of the fluorescence image and the white light image.

[0048] A second filter 8 is provided between the near-infrared camera 6 and the beam splitter prism 3. The surface of the second filter 8 is coated with an interference film layer, so that the fluorescence in the 830-1000nm band is transmitted with a higher transmittance, the transmittance is greater than 95%, and the white light and excitation light signals in the 400-800nm ​​band are highly cut off, and the OD value is at least 3. In this embodiment, if the excitation light source is strong, multiple second filters 8 (bandpass filters) can be used to eliminate the interference of the excitation light source and the white light signal on the fluorescence imaging.

[0049] A first filter 7 (short-pass filter) is provided between the color camera 5 and the beam splitter prism 3. An interference film layer is coated on the surface of the first filter 7, so that the white light signal in the 400-700nm band is transmitted with a relatively high transmittance of more than 99%, while the fluorescence and excitation light signals in the 750-1000nm band are highly cut off, and the OD value thereof is at least 3. In this embodiment, if the excitation light source is relatively strong, a plurality of first filters 7 (short-pass filters) can be used to eliminate the interference of the excitation light and the fluorescence signal on the white light imaging.

[0050] The imaging optical fiber 44 adopts Fujikura 30000-filament optical fiber, each of which has a core diameter of 1.9um and a core spacing of 3.3um. The head end of the imaging optical fiber 44 is provided with a wide-field imaging objective lens group 45, and the full field angle can reach 60°, thereby realizing the detection of tumor cells under fluorescence endoscopy.

[0051] The device proposed in this embodiment is realized based on fluorescence imaging technology. Before using the device for imaging observation, a fluorescent contrast agent is injected into the body by intravenous injection or local injection. The fluorescent contrast agent described here is generally indocyanine green ICG. ICG binds to plasma proteins under 785nm excitation light and releases fluorescence in the 830-900nm band. Directional tracing of cancer cells and tumors can be achieved by capturing and imaging the fluorescence. In addition, the film design of the dichroic prism 3, the first filter 7, and the second filter 8 in this device eliminates the influence of stray light, and has a high transmittance to the light in the target band, wherein the comprehensive transmittance to white light in the 400-700nm band is greater than 91%, and the comprehensive transmittance to fluorescence in the 830-1000nm band is greater than 90%. Therefore, this embodiment can also be used for spontaneous fluorescence imaging of some tissues without the need to inject fluorescent contrast agents, simplifying the surgical process.

[0052] The working process of this embodiment is as follows: the excitation light emitted by the light source assembly 11 passes through the first collimating lens 12, the first adjustable aperture 13, the focusing lens 14, the second adjustable aperture 15, and the second collimating lens 16 in sequence to form a uniform light spot and is incident on the TIR prism 21. After passing through the direction setting of the TIR prism 21 and the digital micro-mirror device DMD22, the excitation light is incident on the beam splitter prism 3, passes through the third prism 33, the second prism 32 and the first prism 31 in sequence, and is incident on the telephoto lens 41. Then, it is focused by the magnifying lens 42 and enters the imaging optical fiber 44 to excite human tissue to produce fluorescence. The wide-field imaging objective lens group 45 obtains white light and fluorescence signals, and enters the magnifying lens 42 through the imaging optical fiber 44 to form parallel light. The white light and fluorescence signals enter the beam splitter prism 3 through the same telephoto lens 41. Then, according to the transmission and reflection bands of the film layers set on each surface of the beam splitter prism 3, the white light signal enters the color camera 5 to obtain a color image, and the fluorescence signal enters the near-infrared camera 6 to obtain a fluorescence image.

[0053] In this embodiment, the co-optical axis design of the excitation light path and the imaging light path is adopted to achieve a high degree of overlap between the excitation light field of view and the imaging field of view, thereby expanding the effective imaging field of view range; through the optimized design of the beam splitter prism, not only the difficulty of the assembly process and image alignment is reduced, but also the pixel-level fusion of the fluorescence image and the color image can be easily achieved; the device proposed in this embodiment adopts a highly integrated design, and the whole is in a handheld and portable form, occupies a small space, is not restricted by the medical environment, and greatly improves the scope of application and flexibility. In addition, this embodiment proposes to use a digital micro-mirror device DMD22 to project a specific non-uniformly distributed pattern to compensate for the non-uniformity in the original light spot, thereby obtaining a highly uniform excitation light spot and improving the quality of fluorescence imaging; at the same time, the device has a high transmittance to fluorescence through a special film layer (a film layer set on the beam splitter prism, the first filter, and the second filter), and the comprehensive transmittance is greater than 90%, which can be used for spontaneous fluorescence imaging of some tissues without the need to inject fluorescent contrast agents, simplifying the surgical process.

[0054] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A handheld fluorescence endoscopic imaging device based on a coaxial optical path, characterized in that: The invention comprises a light homogenizing mechanism (1), a light modulating mechanism (2), a beam splitter prism (3), a light transmission mechanism (4), a color camera (5) and a near-infrared camera (6); the excitation light emitted by the light homogenizing mechanism (1) enters the beam splitter prism (3) through the light modulating mechanism (2); the excitation light of a set wavelength band passes through the beam splitter prism (3) and then enters the light transmission mechanism (4) to excite the fluorescence signal of human tissue; the mixed white light signal and the fluorescence signal enter the beam splitter prism (3) through the light transmission mechanism (4) to be separated; the white light signal enters the color camera (5) to obtain a color image; the fluorescence signal enters the near-infrared camera (6) to obtain a fluorescence image; the optical paths of the white light signal and the fluorescence signal share the telephoto lens (41) of the light transmission mechanism (4); The beam splitter prism (3) is formed by gluing three prisms together, and has two gluing surfaces in total. Each gluing surface is coated with a film layer so that light of a set wavelength is transmitted and light of other wavelength bands is reflected.

2. The handheld fluorescence endoscopic imaging device based on coaxial optical path according to claim 1, characterized in that: The first bonding surface (34) of the two bonding surfaces is coated with a film layer so that white light and excitation light in the 400-800nm ​​band are highly transparent, with a transmittance greater than 99%, and fluorescence in the 830-1000nm band is highly reflected, with a reflectance greater than 99%. The second bonding surface (35) is coated with a film layer so that white light in the 400-700nm band is highly reflected, with a reflectance greater than 95%, and excitation light in the 750-800nm ​​band is highly transparent, with a transmittance greater than 99.5%.

3. The handheld fluorescence endoscopic imaging device based on coaxial optical path according to claim 2, characterized in that: The three prisms are respectively a first prism (31), a second prism (32) and a third prism (33); the first prism (31) and the second prism (32) are connected via a first bonding surface (34), and the second prism (32) and the third prism (33) are connected via a second bonding surface (35); The white light signal and the fluorescence signal enter the first prism (31), pass through the first bonding surface (34), the fluorescence signal in the 830-1000 nm band is reflected and enters the near-infrared camera (6), the light signal in the 400-800 nm band is transmitted and enters the second prism (32), passes through the second bonding surface (35), the white light signal in the 400-700 nm band is reflected and enters the color camera (5), and the excitation light in the 750-800 nm band is transmitted and enters the third prism (33).

4. The handheld fluorescence endoscopic imaging device based on coaxial optical path according to claim 3 is characterized in that: According to the transmission direction of the white light signal and the fluorescent signal, an anti-reflection film is arranged at the incident end of the first prism (31), and has a transmittance greater than 99.5% for light in the 400-1000nm band; a dichroic film is arranged at the output end of the first prism (31), and has high transmittance for fluorescence in the 830-1000nm band, and a transmittance greater than 99.8%, and high reflection for white light and excitation light in the 400-800nm ​​band, and a reflectance greater than 98%; a dichroic film is arranged at the output end of the second prism (32), and has high transmittance for white light in the 400-700nm band, and a transmittance greater than 99%; and high reflection for excitation light in the 750-800nm ​​band, and a reflectance greater than 98%; and an anti-reflection film is arranged at the output end of the third prism (33), and has high transmittance for excitation light in the 750-800nm ​​band, and a transmittance greater than 99.5%.

5. The handheld fluorescence endoscopic imaging device based on coaxial optical path according to claim 1, characterized in that: The light homogenizing mechanism (1) comprises a light source assembly (11), a first collimating lens (12), a first adjustable iris (13), a focusing lens (14), a second adjustable iris (15), and a second collimating lens (16); the excitation light emitted by the light source assembly (11) passes through the first collimating lens (12), the first adjustable iris (13), the focusing lens (14), the second adjustable iris (15), and the second collimating lens (16) in sequence before entering the light homogenizing mechanism (2).

6. The handheld fluorescence endoscopic imaging device based on coaxial optical path according to claim 5, characterized in that: The dimming mechanism (2) is a digital micro-mirror device (DMD) (22). The digital micro-mirror device (DMD) (22) has three states, namely, deflection of +12°, no deflection, and deflection of -12°.

7. The handheld fluorescence endoscopic imaging device based on a coaxial optical path according to claim 1, characterized in that: The light transmission mechanism (4) comprises a telephoto lens (41), a magnifying objective lens (42), a fiber optic probe (43), an imaging fiber (44) and a wide-field imaging objective lens group (45); one end of the imaging fiber (44) is connected to the fiber optic probe (43), and the other end is connected to the wide-field imaging objective lens group (45); the imaging fiber (44) is arranged at the front end of the magnifying objective lens (42); and the wide-field imaging objective lens group (45) acquires a white light signal and a fluorescent signal; The mixed white light signal and fluorescent signal sequentially pass through the imaging optical fiber (44), the optical fiber probe (43), the magnifying objective lens (42), and the telephoto lens (41) and enter the beam splitter prism (3) for light separation.

8. The handheld fluorescence endoscopic imaging device based on coaxial optical path according to claim 1, characterized in that: The imaging incident end of the color camera (5) is provided with a first filter (7), and the imaging incident end of the near-infrared camera (6) is provided with a second filter (8).

9. The imaging method of the handheld fluorescence endoscopic imaging device based on the coaxial optical path according to claim 1, characterized in that: The steps include: The excitation light emitted by the light homogenizing mechanism (1) is incident on the digital micro-mirror device DMD (22) at an angle of 24 degrees via the TIR prism (21) of the light modulating mechanism (2); the digital micro-mirror device DMD (22) allows the excitation light to vertically pass through the TIR prism (21) and be incident on the beam splitting prism (3); The excitation light of the set wavelength passes through the beam splitter prism (3) and reaches the telephoto lens (41) of the light transmission mechanism (4) to become parallel light; The parallel light enters the wide-field imaging objective lens group (45) through the light transmission mechanism (4) to excite the fluorescent signal of the human tissue; The mixed white light signal and fluorescent signal enter the beam splitter prism (3) through the light transmission mechanism (4) for light separation; The white light signal enters a color camera (5) to obtain a color image, and the fluorescence signal enters a near-infrared camera (6) to obtain a fluorescence image.

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