CN117582163A - Endoscopic lighting device - Google Patents

Abstract

The invention discloses an endoscopic lighting device, which comprises a single transverse mode narrow bandwidth laser and a low NA (NA) tapered optical fiber, wherein the single transverse mode narrow bandwidth laser provides high-coherence laser, the light emergent end of the low NA tapered optical fiber is tapered, the light incident end of the low NA optical fiber is directly coupled with the single transverse mode narrow bandwidth laser, the light emergent end of the low NA tapered optical fiber is fixed around an endoscope objective lens, and the laser irradiates on a sample through the tapered end of the low NA optical fiber. The device disclosed by the invention is particularly suitable for endoscopic laser speckle blood flow imaging. The illumination device provided by the invention solves the problems of small illumination field, relatively uneven illumination intensity, low laser coupling efficiency, poor laser illumination coherence and high mirror reflection in the original endoscopic laser speckle blood flow imaging, and has extremely high laser coupling efficiency in the endoscopic imaging environment, and can provide laser illumination with high coherence, large illumination field, high uniformity and low mirror reflection.

Description

Endoscopic lighting device

Technical Field

The invention relates to the field of endoscopic laser illumination, in particular to an endoscopic illumination device for laser speckle blood flow imaging.

Background

In surgery, doctors place great importance on the state of tissue blood flow microcirculation, for example: in organ resection, a doctor needs to visualize a blood vessel in real time; in colorectal cancer resection, a doctor needs to judge the anastomosis condition after tumor resection according to whether blood flow is supplied; acute mesenteric ischemia patients need to evaluate the mesenteric blood flow microcirculation state in real time, and the blood flow microcirculation state has important reference function on the operation.

Laser speckle blood flow endoscopic imaging is a combination of laser speckle blood flow imaging technology (Laser speckle flow imaging, LSFI) and endoscopic imaging, which can realize blood perfusion during operation. LSFI achieves rapid, full-field detection of blood flow by analyzing the degree of blurring caused by dynamic speckle patterns. The laser is used as an illumination light source, the two-dimensional wide-field imaging can be carried out on the blood flow of biological tissues without scanning, the time and the spatial resolution can respectively reach the order of several milliseconds and several micrometers, and the method has the advantages of real-time rapidness, high resolution, no need of contrast agent marking and non-contact detection. The combination of LSFI and endoscope can be used as an effective means for visualizing blood vessels of internal organs and diagnosing diseases in operation, and can provide information of blood supply state or disease assessment in vivo for doctors in real time.

In the existing endoscopic laser speckle blood flow imaging technology, lasers are directly coupled into an endoscope self-carried illumination optical fiber through a large NA multimode optical fiber bundle, the laser illumination field of the laser illumination mode is smaller than the imaging field, illumination intensity is relatively uneven, laser illumination coherence is low, and laser coupling efficiency is low, so that the LSFI field of view is small, blood flow measurement in the field of view is inaccurate, poor contrast-blood flow linear fitting is realized in a working distance, the LSFI effective working distance is short, and larger specular reflection interference exists.

In order to solve the problems in the prior art, the invention adopts the illumination device combining the single transverse mode narrow bandwidth laser and the low NA tapered optical fiber, and can simultaneously provide laser illumination with large illumination field, high power, high coherence, high uniformity and low specular reflection in the short to long working distance under the endoscopic environment.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention discloses an endoscopic laser speckle blood flow imaging (LSFI) lighting device, which comprises a single transverse mode narrow bandwidth laser and a low NA optical fiber, wherein the light emergent end of the low NA optical fiber is conical, the single transverse mode narrow bandwidth laser can provide high-coherence laser required by the LSFI, the low NA optical fiber can greatly maintain high-coherence laser lighting required by the LSFI under an endoscopic environment, and the conical structure at one end of the low NA optical fiber can provide a large laser lighting visual field and uniform laser lighting. The laser is directly coupled with the optical fiber, so that the laser coupling efficiency is extremely high, and the laser is very suitable for endoscopic LSFI with extremely low light utilization rate and high requirements on light intensity. Since the light exit end of the single or multiple low NA tapered optical fibers is fixed around the endoscope objective lens, specular reflection is minimal.

The illumination device provided by the invention solves the problems of small illumination field, relatively uneven illumination intensity, low laser coupling efficiency, poor laser illumination coherence and high mirror reflection in the original endoscopic LSFI, and can provide high coherence under the endoscopic environment, and has the advantages of extremely high laser coupling efficiency, large illumination field, high uniformity and low mirror reflection.

The invention provides an endoscopic laser speckle blood flow imaging lighting device, which comprises a single transverse mode narrow bandwidth laser and a low NA conical optical fiber, wherein the light emergent end of the low NA conical optical fiber is processed into a cone shape. The tapered optical fiber is a section of optical fiber ground to a specific taper angle, and is different from a tapered optical fiber with a thick end and a thin end. The light incident end of the low NA optical fiber is directly coupled with a single transverse mode narrow bandwidth laser, the light emergent end of the low NA optical fiber is fixed around the endoscope objective lens, laser irradiates on a sample through the conical end of the low NA optical fiber, and the single transverse mode narrow bandwidth laser provides laser with high coherence required by LSFI.

Furthermore, the low NA conical optical fiber has a core diameter of 10-600 mu m and NA of 0.18-0.23, the conical angle of the conical end of the conical optical fiber is 10-170 degrees, and the low NA conical optical fiber has a core diameter of 10-600 mu m, so that the burden on an endoscope is extremely small, and the low NA conical optical fiber is very suitable for laser illumination in an endoscopic imaging environment.

Furthermore, the low NA tapered optical fiber is one or more, and is fixed around the endoscope objective lens to generate laser illumination required by endoscopic laser speckle blood flow imaging, and the tapered structure at one end of the low NA optical fiber can provide a large laser illumination field and uniform laser illumination.

Furthermore, one end of the low NA tapered optical fiber is a common optical fiber interface, the other end of the low NA tapered optical fiber is a bare fiber, the low NA tapered optical fiber is directly coupled with the single transverse mode narrow bandwidth laser through the optical fiber interface, and the bare fiber end is tapered.

Further, the power of the single transverse mode narrow bandwidth laser light source is 10-900 milliwatts, the wavelength is 200-2000nm wave band, and the transverse modulus is 1.

Furthermore, the NA of the low NA tapered optical fiber is 0.20-0.22, the core diameter is 200-600 mu m, the cone angle is 20-100 degrees, the scheme is a further preferable scheme, the NA value of the low NA optical fiber only needs to be 0.18-0.23, the core diameter is 10-600 mu m, and the cone angle is 10-170 degrees, which are all within the protection scope of the invention.

Further, the taper angle of the low NA tapered optical fiber is obtained by a polishing method, a etching method, or a fusion taper method.

Further, the lighting device further comprises a mounting seat and a flange, wherein the mounting seat is used for fixing the flange, the flange is used for fixing the low NA conical optical fiber light incident end and is fixed on the mounting seat, and the low NA conical optical fiber light incident end arranged in the flange is driven to move by adjusting the movement of the mounting seat, so that the coupling efficiency between the single transverse mode narrow bandwidth laser light source and the low NA conical optical fiber is highest.

Furthermore, the illumination device also comprises an optical fiber deflection device, wherein the optical fiber deflection device is used for fixing the conical optical fiber and is arranged around the endoscope objective lens.

Further, the lighting device further comprises a linear polarizer, wherein the linear polarizer is arranged at the light outlet of the tapered optical fiber, and the polarizer can change laser emitted from the tapered optical fiber from natural light to linearly polarized light.

A second aspect of the present invention provides the use of an endoscopic laser speckle blood flow imaging illumination device as described above, which is particularly suitable for use in an endoscopic laser speckle blood flow imaging system.

A third aspect of the present invention provides an endoscope, wherein the illumination system of the endoscope employs the endoscopic laser speckle blood imaging illumination device.

In summary, the invention provides a laser lighting device for endoscopic laser speckle blood flow imaging, which comprises a single transverse mode narrow bandwidth laser source, a low NA conical optical fiber, an XYZ translation mounting seat and a flange. The single transverse mode narrow bandwidth laser can provide high-coherence laser required by LSFI, the low NA optical fiber can greatly maintain the coherence of the laser required by the LSFI in an endoscopic environment, and the conical structure of the light emitting end of the low NA optical fiber can provide a large laser illumination field of view and uniform laser illumination. The mounting seat is used for fixing the flange. The flange is used for fixing the low NA conical optical fiber and is fixed on the mounting seat. The low NA conical optical fiber is arranged on the flange, the flange is arranged on the mounting seat, and the low NA conical optical fiber incidence end arranged in the flange is driven to move by adjusting the movement of the mounting seat, so that the coupling efficiency between the single transverse mode, the narrow bandwidth laser light source and the low NA conical optical fiber is highest.

The beneficial technical effects obtained by the invention are as follows:

the illumination device provided by the invention solves the problems of small illumination field, relatively uneven illumination intensity, low laser coupling efficiency and poor laser illumination coherence in the original endoscopic LSFI, can provide high-coherence laser illumination, has extremely high laser coupling efficiency, and has large illumination field and high-uniformity laser illumination.

The tapered optical fiber used by the invention is mainly used for generating high-coherence, high-coupling efficiency, large-angle and high-uniformity laser illumination under an endoscopic environment, and is particularly suitable for endoscopic laser speckle blood flow imaging illumination.

The illumination device provided by the invention can generate high-coherence, high-coupling efficiency, large-angle and high-uniformity laser illumination under an endoscopic environment, and has the following benefits for the endoscopic LSFI:

1. because the imaging principle of the LSFI can detect more accurate and weak blood flow change, the conventional endoscopic LSFI carries out laser coupling and illumination by an endoscope and is provided with a large NA optical fiber bundle, the laser coherence is greatly reduced, and the accuracy of blood flow detection is further reduced.

2. The detector needs to acquire enough laser speckle signals to calculate blood perfusion, and because the fiber bundle has a honeycomb structure, only a core layer in the fiber bundle can transmit laser, and the conventional endoscopic LSFI laser illumination needs to be subjected to three laser coupling processes (laser-multimode fiber bundle-endoscope self-carried light cone-endoscope self-carried illumination fiber) in the fiber bundle, so that the coupling efficiency is lower. For endoscopes, the longer the working distance, the smaller the effective NA, and the less signal laser light from the sample to the camera. The intra-operative working distance (> 30 mm) is long and only a very small fraction of the laser light scattered from the sample reaches the camera. Thus, for endoscopic laser speckle blood imaging, a sufficiently high power laser is required to irradiate the sample. Although the detected laser speckle signal may be increased by selecting a high power laser, the high power laser corresponds to a multi-transverse-longitudinal-mode laser source that produces low coherence laser light that results in inaccurate blood flow measurements. The high coupling efficiency laser illumination provided by the invention provides enough laser speckle signals for the detector, so that the effective working distance of the system is increased while high coherence is maintained.

3. Compared with the conventional endoscopic LSFI laser illumination mode, the laser illumination mode provided by the invention has a larger illumination angle. The laser is coupled into the laparoscope by the multimode fiber bundle and provided with an illumination fiber, and the illumination angle of the emergent laser is far smaller than the imaging view field. In the invention, the cone-shaped optical fiber can improve the distribution of emergent light by changing the cone angle, and the laser illumination field of view is close to the imaging field of view by processing the optical fiber into a specific cone angle, so that the effective imaging field of view of the endoscopic LSFI is increased.

4. Laser illumination of uniform intensity is important for accurate measurement of blood flow in the imaging field of view, and laser illumination of the endoscope with its own optical fiber is uneven in the imaging field of view, resulting in relatively inaccurate blood flow measurement. The tapered optical fiber illumination provided by the invention can generate uniform laser illumination, and compared with the conventional endoscopic LSFI, the laser illumination mode provided by the invention has the advantage that blood flow measurement in an imaging visual field is more accurate.

5. The mucosal layer in the cavity has a smooth appearance, often causing specular reflection at imaging, and the specular reflection region LSFI signal is submerged, although this effect can be eliminated by orthogonal polarizers, which results in a 75% loss of laser speckle signal. The conventional endoscopic LSFI laser illumination optical fiber is positioned around the imaging channel, the illumination has higher specular reflection, the tapered optical fiber provided by the patent is positioned on one side of the imaging channel, and the specular reflection brought by the illumination is less, so that the effective imaging area of the endoscopic LSFI is increased.

Drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention, and the reference numerals of the accompanying drawings are: a single transverse mode narrow bandwidth laser source 1, a low NA tapered optical fiber 2, an XYZ translational mount 3, a flange 4, an endoscope 5, an imaging lens 6, and a detector 7.

Fig. 2 is a schematic view of a plurality of tapered optical fibers fixed around an objective lens, wherein 9 is an endoscope objective lens.

Fig. 3 is a schematic view of a 30 ° angular deflection of a tapered fiber illumination, wherein 8 is a fiber deflection device.

FIG. 4 is a graph showing the contrast of laser illumination angles produced by a normal fiber and a tapered fiber.

Fig. 5 is a schematic view of endoscopic LSFI imaging under different illumination modes.

Fig. 6 is a graph showing the contrast of illumination fields under different illumination modes.

FIG. 7 is a graph showing the contrast of specular reflection under different illumination modes.

FIG. 8 is a graph showing uniformity fluctuations for different illumination modes.

Fig. 9 is a graph comparing laser power and coupling efficiency for different illumination modes.

Fig. 10 is a graph of speckle contrast versus illumination for different illumination modes.

Fig. 11 is a view illustrating a mode of fixing a linear polarizer, in which 10 is a protective cover and 11 is a linear polarizer.

Identification description: the device comprises an endoscope, an LDSFL, an MMLDCF, a multi-transverse-mode narrow bandwidth laser, an MMLDSFL, a multi-transverse-mode narrow bandwidth laser, a low NA taper optical fiber and an LDSFL, wherein the LDCF is a lighting device for coupling a single-transverse-mode narrow bandwidth laser into a low NA optical fiber bundle and then coupling the single-transverse-mode narrow bandwidth laser into the low NA optical fiber bundle of the endoscope; MMLDGFL is an illumination device with multiple transverse modes and narrow bandwidths of lasers coupled into a high NA fiber bundle and then coupled into an endoscope self-contained fiber bundle.

Detailed Description

The present invention will be described in further detail with reference to the following examples and the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It is to be understood that the following description is intended to be illustrative of the invention and not restrictive.

The terms "comprising," "including," "having," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

When an equivalent, concentration, or other value or parameter is expressed as a range, preferred range, or a range bounded by a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when ranges of "1 to 5" are disclosed, the described ranges should be construed to include ranges of "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a numerical range is described herein, unless otherwise indicated, the range is intended to include its endpoints and all integers and fractions within the range.

In some examples, the approximating language may correspond to the precision of an instrument for measuring the value. In the present description and claims, the range limitations may be combined and/or interchanged. These ranges include all subranges subsumed therebetween, if not otherwise stated.

The indefinite articles "a" and "an" preceding an element or component of the invention are not limited to the requirement (i.e. the number of occurrences) of the element or component. Thus, the use of "a" or "an" should be interpreted as including one or at least one, and the singular reference of an element or component includes the plural reference unless the amount clearly dictates otherwise.

The description of the terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., herein describe means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily for the same embodiment or example. The technical features of the respective embodiments of the present invention may be combined with each other as long as they do not collide with each other.

The materials and equipment used in the present invention are commercially available or are those commonly used in the art, and the methods described in the examples are those commonly used in the art unless otherwise specified.

The first aspect of the invention provides an endoscopic laser speckle blood flow imaging illumination device, which comprises a single transverse mode narrow bandwidth laser and a low NA tapered optical fiber. The single transverse mode narrow bandwidth laser provides the high coherence laser light required for endoscopic LSFI. The light emitting end of the low NA conical optical fiber is processed into a cone shape, the light incident end of the low NA optical fiber is directly coupled with the single transverse mode narrow bandwidth laser, the light emitting end of the low NA optical fiber is fixed around the endoscope objective lens, and laser irradiates on a sample through the conical end of the low NA optical fiber.

Further, the low NA tapered optical fiber has a core diameter of 10-600 μm, optionally 20, 50, 100, 200, 300, 400, 500 or 600 μm, further NA of 0.18-0.23, optionally 0.18,0.19,0.20,0.21, 0.22, 0.23, etc., and the tapered end of the tapered optical fiber has a taper angle of 10-170 DEG, and the taper angle degree is optionally 10 DEG, 30 DEG, 50 DEG, 70 DEG, 90 DEG, 110 DEG, 130 DEG, 150 DEG, 170 DEG, etc.

Further, the number of the low NA tapered optical fibers is one or more, and as shown in fig. 2, the number of the low NA tapered optical fibers may be 1, 2, 3, and 4, which are fixed around the objective lens of the endoscope.

Furthermore, one end of the low NA tapered optical fiber is a common optical fiber interface, the other end of the low NA tapered optical fiber is a bare fiber, the low NA tapered optical fiber is directly coupled with the single transverse mode narrow bandwidth laser through the optical fiber interface, and the bare fiber end is tapered. Further, the fiber interface may be FC/PC, SMA, etc.

Further, as shown in fig. 3, the low NA tapered fiber illumination angle is changed by adding a fiber deflection angle device.

Further, the single transverse mode narrow bandwidth laser and the low NA tapered fiber are coupled by direct coupling, and other coupling modes, such as lens coupling, fiber coupling, etc., are still within the scope of protection.

Further, the power of the single transverse mode narrow bandwidth laser light source is 10-900mw, and can be 20mW,50mW,200mW,400mW,600mW and the like. The single transverse mode narrow bandwidth laser diode with wavelength of 200-2000nm can be selected from 200nm,500nm,800nm,1200nm,160 nm, etc.

Furthermore, the NA of the low NA tapered optical fiber is 0.21, the core diameter is 400 mu m, the cone angle is 33.2 degrees, the scheme is a further preferable scheme, the NA value of the low NA optical fiber only needs to be 0.18-0.23, the core diameter is tens to hundreds of micrometers, and the cone angle is 10-170 degrees, which are all within the protection scope of the invention.

Further, the taper of the low NA tapered optical fiber is obtained by a polishing method, a etching method or a fusion taper method.

Further, the lighting device further comprises a mounting seat and a flange, wherein the mounting seat is used for fixing the flange, the flange is used for fixing the low NA tapered optical fiber and is fixed on the mounting seat, and the mounting seat is adjusted to move to drive the low NA tapered optical fiber incidence end arranged in the flange to move, so that the coupling efficiency between the single transverse mode narrow bandwidth laser light source and the low NA tapered optical fiber is highest.

The second aspect of the invention provides the use of the endoscopic laser speckle blood flow imaging lighting device, and the endoscopic laser speckle blood flow imaging lighting device is used for an endoscopic laser speckle blood flow imaging system.

The third invention provides an endoscope, wherein the illumination system of the endoscope adopts the endoscopic laser speckle blood flow imaging illumination device.

The invention is further illustrated in the following in connection with specific embodiments:

referring to fig. 1, in order to couple a single transverse mode narrow bandwidth laser light source 1 into a low NA tapered optical fiber 2, the low NA tapered optical fiber 2 with an optical fiber interface at one end is fixed on a flange 4, external threads of the flange 4 are coupled with internal threads of an XYZ translation mounting seat 3, an XYZ shaft knob of the XYZ translation mounting seat 3 is adjusted, and the low NA tapered optical fiber 2 mounted in the flange 4 is driven to move up and down back and forth and left and right so that a laser and an optical fiber core diameter are positioned at the same position, so that laser coupling efficiency is highest. The light emitting end of the low NA conical optical fiber 2 can be fixed around the objective lens of the endoscope 5 in a fixing mode such as an adhesive tape, laser irradiates on a sample after passing through the low NA conical optical fiber 2, and laser scattered by the sample is imaged on the detector 7 through the endoscope 5 and the imaging lens 6, so that the endoscopic LSFI is completed.

Referring to fig. 4, fig. 4 shows a simulated comparison of the illumination of a tapered fiber and a normal fiber laser. The simulation was done by ZEMAX. Fig. 4 a is the outgoing light of the laser passing through the conventional optical fiber (na=0.22, a=200 μm), and fig. 4 b is the outgoing laser intensity of the laser at a working distance of 15mm after passing through the conventional optical fiber; in fig. 4, c is the outgoing beam of the laser after passing through the tapered fiber (na=0.22, a=200 μm, the core layer of the fiber is designed to be tapered at a specific angle), and d is the outgoing laser intensity of the laser after passing through the tapered fiber at a working distance of 15 mm. As can be seen from the comparison of the figures, the illumination range of c in fig. 4 is larger, and the uniformity of the intensity of light is better, so that the optical fiber core layer is processed into a cone shape, the emergent angle of the optical fiber can be greatly increased, and the uniformity of illumination is remarkably improved.

The invention further compares the effect of the illumination device of the invention with that of a conventional endoscopic LSFI laser illumination device, mainly shown in fig. 5, and a-f in fig. 5 show the influence of single and multi-transverse mode lasers, coupling fibers and the numerical aperture of the coupling fibers on laser illumination. The concrete steps are as follows: different lasers (single and multiple transverse mode narrow bandwidth lasers) are coupled into different optical fibers (tapered optical fibers, first into a low NA optical fiber bundle and then into an endoscope self-contained optical fiber bundle, first into a high NA optical fiber bundle and then into an endoscope self-contained optical fiber bundle), illuminated on the same white card with graduations, and imaged on a detector through an endoscope and a focusing lens.

As shown in a of fig. 5, a of fig. 5 is a graph of an illumination effect of a single transverse mode narrow bandwidth laser coupled into a low NA tapered optical fiber, and it can be seen from the graph that the single transverse mode narrow bandwidth laser is coupled into the low NA tapered optical fiber to have the largest illumination field, uniform illumination of an imaging field and the highest laser speckle contrast.

As shown in b of fig. 5, b of fig. 5 is an illumination effect diagram of coupling a single transverse mode narrow bandwidth laser into a low NA fiber bundle and then coupling the single transverse mode narrow bandwidth laser into an endoscope self-contained illumination fiber bundle, and as can be seen from the figure, the obtained speckle contrast is high, but the illumination field is small, and the illumination within the imaging field is uneven.

As shown in c in fig. 5, c in fig. 5 is an illumination effect diagram of coupling a single transverse mode narrow bandwidth laser into a high NA fiber bundle and then into an endoscope self-contained illumination fiber bundle, and as can be seen from the figure, the obtained speckle contrast is lower, and the illumination field of view is smaller than that of coupling a single transverse mode narrow bandwidth laser of the present invention into a low NA tapered fiber (a in fig. 5).

As shown by d in fig. 5, d in fig. 5 is a graph of the illumination effect of a multi-transverse mode narrow bandwidth laser coupled into a low NA tapered fiber, where it can be seen that the obtained speckle contrast is low, the illumination field is large, and the illumination intensity within the illumination field is relatively uniform.

As shown in e in fig. 5, e in fig. 5 is an illumination effect diagram of coupling a multi-transverse mode narrow bandwidth laser into a low NA fiber bundle and then coupling the multi-transverse mode narrow bandwidth laser into an endoscope self-carried illumination fiber bundle, and as can be seen from the figure, the obtained speckle contrast is low, the illumination field is small, and the illumination intensity in the illumination field is relatively uneven.

As shown by f in fig. 5, f in fig. 5 is an illumination effect diagram of coupling a multi-transverse mode narrow bandwidth laser into a high NA fiber bundle and then coupling the multi-transverse mode narrow bandwidth laser into an endoscope self-contained illumination fiber bundle, and it can be seen from the figure that the obtained speckle contrast is extremely low, the illumination field is partially absent, and the illumination intensity in the illumination field is relatively nonuniform.

In summary, the illumination effect of coupling the single transverse mode narrow bandwidth laser into the low NA tapered optical fiber is best, the illumination field is the largest, the imaging field is uniform in illumination, the laser speckle contrast is the highest, and the accuracy of LSFI detection of blood flow can be improved by adopting the illumination device of coupling the single transverse mode narrow bandwidth laser into the low NA tapered optical fiber based on the principle of laser speckle imaging.

In order to specifically demonstrate the benefits of the invention compared with conventional endoscopic LSFI laser illumination, the illumination field, specular reflection, illumination uniformity, output power and coupling efficiency, and speckle contrast under various coupling modes were calculated. Fig. 6-10 show a specific analysis of the benefits of the present invention over conventional endoscopic LSFI laser illumination.

As shown in fig. 6, the tapered fiber has a larger illumination field of view than other fiber coupling approaches, with an illumination field of view/imaging field of view approaching 0.95.

As shown in fig. 7, the use of the laparoscopic self-illuminated mode has a higher specular reflection due to the laparoscopic inherent illumination and imaging mode, while the tapered fiber has an extremely low specular reflection compared to the laparoscopic self-illuminated mode, and does not even require the addition of orthogonal polarizers to eliminate specular reflection during imaging. Without the use of orthogonal polarizers, the signal reaching the camera can be increased by a factor of 4.

The uniform laser intensity is important for the LSFI, and the uniform fluctuation of illumination of various coupling modes is measured and calculated, as shown in fig. 8, compared with other illumination modes, the endoscopic LSFI laser illumination mode provided by the invention can realize the most uniform laser illumination.

LSFI requires a laser of sufficient power to reach the camera. The power and coupling efficiency of various coupling modes to the sample were measured and calculated, and it was found that LDCF had the highest coupling efficiency and higher power, MMLDCF had the highest power and higher coupling efficiency, see fig. 9, but the speckle contrast of MMLDCF was poor compared to LDCF.

As shown in fig. 10, LDCF and LDSFL have higher speckle contrast than other coupling approaches. In particular, LDSFL has a high overall speckle contrast compared to LDGFL, but a smaller illumination field of view (as in fig. 6). This is because the first half of the low NA fiber bundle brings less loss of coherence before coupling into the laparoscope; in addition, the laser light may generate multimode fiber interference (MMFI) in the optical fiber, the first MMFI is excited by the fundamental mode of the single transverse mode LD, the low NA (0.22) optical fiber bundle of the LDSFL excites a relatively low order mode compared to the high NA (0.60) optical fiber bundle of the LDGFL, in the second MMFI (i.e., coupled into the laparoscope), the MMFI is excited by the mode generated by the first MMFI, the low order mode light generated by the first MMFI of the LDSFL excites the light of the same relatively low order mode in the illumination fiber of the laparoscope, the low order mode light corresponds to a small divergence angle, the high order mode light corresponds to a large divergence angle, and the high order mode light generated by the first MMFI of the LDGFL excites the light of the same relatively high order mode in the illumination fiber of the laparoscope, so the LDSFL has a smaller divergence angle compared to the LDGFL.

In a word, by comparing the illumination view field, the specular reflection quantity, the illumination uniformity, the output power, the coupling efficiency and the speckle contrast ratio under various coupling modes, the endoscopic LSFI laser illumination mode provided by the invention can exert the best performance on the illumination view field, the illumination uniformity, the specular reflection quantity, the coupling efficiency and the speckle contrast ratio.

The above embodiments are not intended to limit the scope of the present invention, so: all equivalent changes in structure, shape and principle of the invention should be covered in the scope of protection of the invention.

Claims (10)

1. The utility model provides an endoscopic lighting device, includes single transverse mode narrow bandwidth laser instrument and low NA toper optic fibre, low NA toper optic fibre's light exit end is the toper, low NA toper optic fibre's light incident end and single transverse mode narrow bandwidth laser instrument coupling, low NA toper optic fibre light exit end is fixed around the endoscope objective, and laser irradiates on the sample through the toper end of low NA toper optic fibre, single transverse mode narrow bandwidth laser instrument provides the laser of high coherence.

2. An endoscopic illumination device according to claim 1, wherein said low NA tapered fiber has a core diameter of 100-600 μm and a NA of 0.18-0.23, and the tapered end of said low NA tapered fiber has a taper angle of 10 ° -170 °.

3. An endoscopic illumination device according to claim 1, wherein the low NA tapered optical fibers are one or more, the low NA tapered optical fibers being evenly distributed around the endoscope objective; and/or the cone angle of the low NA tapered optical fiber is obtained by a grinding method, an etching method or a fusion tapering method.

4. An endoscopic lighting device according to claim 1, wherein said low NA tapered fiber entrance port is an FC/PC or SMA fiber interface, the light exit port is a bare fiber, the light exit port is tapered, and said low NA tapered fiber entrance port and single transverse mode narrow bandwidth laser are coupled in a direct coupling, lens coupling or fiber coupling manner.

5. An endoscopic lighting device according to any one of claims 1-4, wherein the single transverse mode narrow bandwidth laser light source has a wavelength of 200-2000nm band, a transverse modulus of 1 and a power of ten milliwatts to nine hundred milliwatts.

6. An endoscopic illumination device according to any one of claims 1-4, wherein the illumination device further comprises an optical fiber deflection device, the deflection device fixing a tapered optical fiber and being mounted around the endoscope objective lens.

7. An endoscopic lighting device according to any one of claims 1-4, further comprising a linear polarizer mounted at the light exit opening of the tapered fiber, the polarizer being adapted to change the laser light emitted from the tapered fiber into linearly polarized light.

8. The endoscopic lighting device according to any one of claims 1-4, further comprising a mounting base and a flange, wherein the mounting base is used for fixing the flange, the flange is used for fixing the low NA tapered optical fiber and is fixed on the mounting base, and the low NA tapered optical fiber incident end installed in the flange is driven to move by adjusting the movement of the mounting base, so that the coupling efficiency between the single transverse mode narrow bandwidth laser light source and the low NA tapered optical fiber is the highest.

9. The use of an endoscopic illumination device according to any one of claims 1 to 8, wherein said endoscopic illumination device is used in an endoscopic imaging system.

10. An endoscope, characterized in that the illumination system of the endoscope comprises an endoscopic illumination device according to any of claims 1-8.