CN115781583B

CN115781583B - Method for assembling confocal endoscopic probe

Info

Publication number: CN115781583B
Application number: CN202310087101.6A
Authority: CN
Inventors: 许航; 郭海中; 杨青; 徐璟罡; 文仲; 刘旭; 孟雷欣
Original assignee: Zhejiang University ZJU; Zhejiang Lab
Current assignee: Zhejiang University ZJU; Zhejiang Lab
Priority date: 2023-02-09
Filing date: 2023-02-09
Publication date: 2023-04-28
Anticipated expiration: 2043-02-09
Also published as: CN115781583A

Abstract

The invention discloses an assembly method and a device of a confocal endoscopic probe, which uses a mirror surface positioning instrument to accurately position a micro distance, and the assembly method is characterized in that a multi-section protective sleeve structure which is uniquely designed in the assembly method is perfectly matched with the assembly flow of the invention, the position of an internal optical fiber bundle and a GRIN lens is fixed while the internal optical fiber bundle and the GRIN lens are protected, and the function of shielding the interference of external optical signals can be realized, so that the assembly method of the confocal endoscopic probe has more feasibility and practicability. The design and the assembly process of the micro lens are independently explored, a set of complete micro lens assembly flow is developed, the transverse resolution of 1.07 mu m is achieved, the whole imaging view field reaches 230 mu m, the imaging can be carried out by being clung to the surface of a sample, and the cell-level imaging of pathological tissues is facilitated. Lay the foundation for the design and assembly of the follow-up lateral and infrared large-depth lens, be favorable to realizing localization of core components, reduce the cost of medical equipment, and promote the national medical level.

Description

Method for assembling confocal endoscopic probe

Technical Field

The invention relates to the field of endoscopic imaging, in particular to an assembly method and device of a confocal endoscopic probe.

Background

Cancer has gradually become one of the leading causes of death in humans in recent years. Research has shown that the key to treating cancer is how to improve the diagnostic efficiency for early cancers. Electronic endoscopic-based biopsy remains the only gold standard currently accepted for diagnosing cancer. Doctors judge benign and malignant tumors through in-vivo spot check and in-vitro identification, but the spot check has the phenomena of missing check and false check. Confocal imaging has received much attention in recent years due to its high resolution and high signal-to-noise ratio. Compared with other endoscopes, the diameter of a single fiber core of the fiber bundle is only a few micrometers, the subcellular resolution can be achieved, accurate judgment can be made on benign and malignant of pathological cells in vivo in real time, and the diagnosis efficiency and accuracy can be greatly improved; secondly, when doctors use the optical fiber bundle confocal endoscope to carry out medical examination, the diameter of the endoscope can be less than 1mm, so that invasive damage to patients can be reduced, and postoperative recovery of the patients can be quickened; the other side is also beneficial for the endoscope to enter into the more narrow areas such as the biliary pancreatic duct and the like for exploration. Therefore, the confocal technology is applied to endoscopic imaging, and is expected to realize in-vivo real-time high-resolution imaging of lesion tissues.

Currently, confocal microscopy has become the most widely used histological observation microscope for biological cells. Due to its ultra-high optical resolution and good image signal to noise ratio, it is able to observe cell morphology on a sub-cellular scale. In addition, doctors acquire fluorescence images of the inside of tissue cells by combining the tissue cells with fluorescent probes, and detect physiological information such as membrane potential and calcium ion signals in real time, so that the development of multiple subjects such as pathology, cytobiology and immunology is greatly promoted.

However, the assembly of such tiny optical fiber bundle confocal endoscopic probe forms a big difficulty, and generally the GRIN lens is combined with a microscopic system, so that the GRIN lens can be used as a probe to enter a human body for precise observation, and because the GRIN lens is small and needs to be at a certain distance from tissues, the GRIN lens is easy to vibrate, so that the image surface is dithered, the GRIN lens needs to be firmly fixed, and the positions of the GRIN lens and an observed object and the positions of the GRIN lens and the end face of the optical fiber bundle need to be precisely controlled.

In the literature (Wang Cheng, liu Yong, any autumn, endoscopic laser confocal microscope [ J ]. Laser biology report, 2005,14 (5): 388-392.), a microminiature endoscope structure for confocal imaging is designed, and an optical element of a probe portion is integrated in a fused quartz tube with the diameter of 2 mm, so that three-dimensional scanning of a sample is realized. But its diameter is slightly larger and there is an external optical signal disturbance at the probe. In 2018, a method has been proposed in the literature (Youyou He, cuifangKuang, qing Yang, "Research on fiber bundle confocal fluorescence microendoscope based on sub-pixel", the West Lake PhotonicsSymposium, hangzhou, china, oct 26, 2018.) to measure the distance between the two optically, i.e. to monitor the adjustment process by means of wide field imaging. The wide-field imaging device comprises a CCD, a 4f system consisting of an objective lens and a field lens, a five-dimensional adjusting frame, a resolution plate, a field calibration plate and an endoscopic probe element. In the bonding process, parameters to be adjusted include an object side working distance and an image side working distance, namely, a distance between a sample and an objective lens and a distance between the objective lens and an optical fiber. The end face of the optical fiber bundle is firstly adjusted to be on the focal plane of the objective lens. Then placing a resolution plate and a view field calibration plate on the focal plane of the small objective lens, dripping a proper amount of deionized water between the small objective lens and the resolution plate, observing and imaging by using a CCD, and adjusting the positions of the optical fiber bundle, the objective lens and the sample in the air to make the imaging clearer. And then the packaging of the optical fiber probe also needs to use ultraviolet curing glue to bond the optical fiber bundle and the objective lens, and the refractive index of the image side can be changed after glue dripping, so that the image distance is changed, the distance between the optical fiber and the objective lens is required to be adjusted in the same judging mode before curing after glue dripping, and finally the sample is clearly visible. And finally, the curing operation is finished, the change of an imaging result in the curing process is detected in real time through a CCD, and finally, the brass sleeve is fixed at the bonding part, so that the protection effect is realized. However, in the process of assembling, positioning and adjusting the probe, two intervals are adjusted simultaneously, the variables are too many, the assembling method is complex, and the feasibility is low. And the whole shell is a section of brass sleeve, the material is easy to rust, the service time is short, and the risk is high. The other section brass sleeve plays a role in protecting the probe, and meanwhile, the lens in the probe is inconvenient to assemble, and the situation that liquid enters the probe possibly occurs in the use process.

Disclosure of Invention

The invention aims to provide an assembly method and device of a confocal endoscopic probe. The invention explores the design and the assembly process of the micro lens, develops a complete micro lens assembly method and device, uses a mirror surface positioning instrument to accurately position the micro distance, perfectly matches the assembly process of the invention by adopting the multi-section type shell structure uniquely designed in the invention, realizes the fixation of the positions of the internal optical fiber bundle and the GRIN lens while protecting the internal optical fiber bundle and the GRIN lens, and can realize the function of shielding the interference of external optical signals, so that the assembly method of the confocal endoscopic probe has more feasibility and practicability. Meanwhile, the invention can also be used for assembling the lateral GRIN lens. The invention also lays a foundation for the design and assembly of the infrared large-depth lens, is beneficial to realizing the localization of core components, reduces the cost of medical equipment and improves the national medical level.

The technical scheme adopted by the invention is as follows:

a method of assembling a confocal endoscopic probe, comprising:

step one: controlling and adjusting the relative distance between a parallel flat crystal and the GRIN lens, wherein a mirror surface positioning instrument is used for measuring the distance between the surface of the imaging side of the GRIN lens and the parallel flat crystal in the adjusting process until the adjustment is stopped for the working distance of an object and the relative position of the parallel flat crystal and the GRIN lens is fixed;

step two: sleeving a first stainless steel protective sleeve outside the GRIN lens, wherein one end face of the first protective sleeve is tightly contacted with the parallel flat crystals, and the other end of the first protective sleeve is shorter than the GRIN lens;

step three: fixing the relative positions of the GRIN lens and the first protective sleeve by gluing and curing;

step four: sequentially placing the optical fiber bundle and the other end of the GRIN lens into a second protective sleeve; and measuring and determining the working distance of the image space between the GRIN lens and the end face of the optical fiber bundle by using a resolution plate wide field imaging device, and gluing, solidifying and fixing the relative position in the measuring process to complete the assembly of the confocal endoscopic probe.

In the first step, an adjusting device is used for respectively loading parallel flat crystals and a fixture for clamping the GRIN lens, and the adjusting device is used for controlling and adjusting the relative distance between the parallel flat crystals and the GRIN lens.

Further, the adjusting device is a three-dimensional adjusting frame, a four-dimensional adjusting frame and a five-dimensional adjusting frame.

Further, the clamping part of the tool clamp is made of a Teflon material.

Further, the tool clamp is manufactured by adopting an additive or subtractive method.

Further, the mirror positioner is a device or system that can be used for precise positioning, such as michelson interference and microscopic measurement light paths.

Further, the GRIN lens is a radial GRIN lens or a lateral GRIN lens.

Further, the first protective sleeve and the second protective sleeve are made of stainless steel.

An apparatus for assembling a confocal endoscopic probe, comprising:

the clamping module comprises a fixture clamp and is used for clamping the GRIN lens;

the positioning module comprises an adjusting device, a mirror surface positioning instrument and a resolution plate wide field imaging device; the adjusting device is used for loading parallel flat crystals and a fixture clamp for clamping the GRIN lens, and controlling and adjusting the relative distance between one parallel flat crystal and the GRIN lens; the mirror surface positioning instrument is used for measuring the distance between the surface of the imaging side of the GRIN lens and the parallel flat crystals; the resolution plate wide field imaging device is used for measuring and determining the working distance between the GRIN lens and the end face of the optical fiber bundle.

Further, the device also comprises a calibration module for calibrating the imaging effect of the assembled confocal endoscopic probe; the calibration module is a resolution plate wide field imaging device.

Compared with the prior art, the method has the following beneficial effects:

according to the invention, the mirror surface positioning instrument is used for accurately positioning the object space working distance of the GRIN lens independently, and the resolution plate wide field imaging system is used for positioning the image space working distance after the object space working distance is fixed, so that the variable parameters are reduced, and the positioning operation is facilitated. And the mirror surface positioning instrument is used for positioning the working distance of the object side of the GRIN lens, and meanwhile, the operation of fixing the working distance of the object side is convenient. The problem that the positioning operation is complex because the object space working distance and the image space working distance are required to be adjusted simultaneously by using the resolution plate wide field imaging system only for positioning is solved, namely, two variable parameters are adjusted simultaneously.

The method is simple to operate, can be used for assembling other micro lenses, ensures that the assembled confocal endoscopic probe reaches the transverse resolution of 1.07 mu m, ensures that the whole imaging view field reaches 230 mu m, and can be closely attached to the surface of a sample for imaging.

Drawings

Fig. 1 shows a flow chart of the method of the invention.

Fig. 2 shows a schematic diagram of a radial confocal endo-probe assembled by the method of the invention.

Fig. 3 shows a schematic diagram of a side confocal endo-probe assembled by the method of the invention.

Figure 4 shows a schematic view of the assembly of GRIN lenses in a radial confocal endoscope probe assembled by the method of the invention.

Figure 5 shows a schematic diagram of the assembly of GRIN lenses in a lateral confocal endoscopic probe assembled by the method of the present invention.

Figure 6 shows a schematic diagram of the assembled ranging of GRIN lenses in a confocal endoscopic probe assembled in accordance with the method of the present invention.

FIG. 7 shows a diagram of a radial resolution plate wide field imaging ranging and testing apparatus assembled by the method of the present invention.

FIG. 8 shows a diagram of a lateral resolution plate wide field imaging ranging and testing apparatus assembled by the method of the present invention.

Fig. 9 shows a graph of the imaging effect of the confocal endoscopic probe assembled by the method of the present invention.

FIG. 10 is a table showing the basis of the imaging effect of the confocal endoscopic probe assembled by the method of the present invention.

1-Teflon protective sleeve, 2-optical fiber bundle, 3-second protective sleeve, 4-image space working distance, 5-black glue, 6-radial GRIN lens, 7-first protective sleeve, 8-object space working distance, 9-lateral GRIN lens, 10-third protective sleeve, 11-upper five-dimensional adjusting frame, 12-parallel flat crystal, 13-fixture, 14-lower five-dimensional adjusting frame, 15-short coherent light source, 16-optical signal transmission path, 17-coupler, 18-collimator, 20-GRIN lens, 21-scannable reference mirror, 22-photodiode, 23-interference signal, 24-CCD, 25-field lens, 26-objective lens, 27-fixture, 28-resolution plate, 29-LED lamp.

Description of the embodiments

The following provides a detailed description of the technical scheme of the present invention by referring to the accompanying drawings.

The invention discloses an assembly method of a confocal endoscopic probe, which is matched with a mirror surface positioning instrument and a wide-field imaging device, is simple to operate, has feasibility and is suitable for assembling a micro lens.

As shown in FIG. 1, the invention discloses a method for assembling a confocal endoscopic probe. Before assembly, all used devices and equipment are prepared, including two sections of polished and cleaned sleeves with an inner diameter dimension not smaller than 0.8 mm and an outer diameter dimension not larger than 1mm are respectively used as a first protective sleeve and a second protective sleeve, a customized GRIN lens, a fixture, a mirror positioner, a parallel flat crystal, two adjusting devices, an optical fiber bundle, glue for fixing including black glue and ultraviolet glue, an ultraviolet lamp for curing ultraviolet glue and the like. Wherein, the first protective sleeve and the second protective sleeve should be made of non-rusting and nontoxic materials, and stainless steel is adopted in the embodiment. The adjusting device is a device which can accurately adjust the space position and fix the space position, such as a three-dimensional adjusting frame, a four-dimensional adjusting frame, a five-dimensional adjusting frame and the like. The fixture is used for clamping tiny GRIN lenses, optical fiber bundles and protective sleeves, and other materials which do not damage the optical fiber bundles, the stainless steel protective sleeves and the GRIN lenses, such as Teflon materials and the like, should be adopted; preferably, the main body part of the fixture is processed by aluminum materials, and the clamping block part is manufactured by Teflon materials through an additive or subtractive method, including 3D printing, metal cutting, grinding and the like. As shown in fig. 1, the method of the present invention is specifically as follows:

and respectively fixing the parallel flat crystals and the fixture on different five-dimensional adjusting frames. When the assembly is started, the whole structure is kept horizontal by adjusting the five-dimensional adjusting frame. The GRIN lens is clamped by using a fixture, then the fixture for loading the GRIN lens is continuously moved towards the parallel crystal direction by adjusting a five-dimensional adjusting frame, the surface of the imaging side of the GRIN lens is continuously close to the parallel crystal, a mirror surface positioning instrument is used for measuring an air gap between the GRIN lens and the mirror surface positioning instrument for multiple times, finally the distance between the GRIN lens and the mirror surface positioning instrument reaches the object working distance, after the multiple measurement data are relatively stable, a first protective sleeve is sleeved on the GRIN lens, one end face of the first protective sleeve is in close contact with the parallel crystal, the other end of the first protective sleeve is shorter than the GRIN lens, at the moment, a certain ultraviolet adhesive is smeared at the joint of the first protective sleeve and the GRIN lens, the ultraviolet adhesive is solidified for three minutes by using an ultraviolet lamp, the GRIN lens with the first protective sleeve is taken down, and the bonding effect is strengthened by radiating for three hours under the ultraviolet lamp.

After the object space working distance is fixed, the image distance between the image surface of the lens and the optical fiber bundle needs to be ensured to form a clear image. At this time, a second protective sleeve of length 10, mm, having an inner diameter of 0.8, mm and an outer diameter of 1, mm, is sleeved over the other end of the GRIN lens having the first protective sleeve for limiting the position, thereby facilitating the subsequent insertion of the optical fiber bundle into a fixed position therein. And then the GRIN lens sleeved with the protective sleeve is re-fixed in the fixture, the optical fiber bundle is also fixed by the fixture, the measurement and the image distance fixation are carried out, and in the process, the position of the optical fiber bundle is fixed in a mode of carrying out wide-field imaging on the resolution plate without the help of a mirror surface positioning instrument.

And fixing the fixture clamping the GRIN lens fixed in the first protective sleeve and the second protective sleeve on the three-dimensional displacement table. A resolution plate and a CCD light source are arranged at the rear end of the first protective sleeve, an objective lens, a field lens and a CCD are arranged at the SMA interface end of the optical fiber bundle, the relative position and angle of the SMA interface and the objective lens are adjusted, so that a clearly visible hexagonal honeycomb structure appears on the CCD, and then the end face of the optical fiber bundle is considered to be positioned on the focal plane of the objective lens. The other end of the optical fiber bundle is arranged in an optical fiber bundle fixture, and the fixture is fixed on a five-dimensional adjusting frame and can move along the axial direction. And (3) turning on the LED lamp, dripping a small amount of deionized water between the resolution plate and the GRIN lens, and observing the imaging effect of the resolution plate by using a CCD. The distance between the cores of the fiber bundle is about 3.5 μm, and the magnification of the self-focusing lens is 1:2.6, so the theoretical resolution of the fiber bundle confocal lens is about 1.35 μm. And then continuously moving the position of the optical fiber bundle along the axial direction to enable the imaging of the resolution board to reach the theoretical effect value as much as possible.

And then, ultraviolet glue is dripped into the joint of the second protective sleeve and the GRIN lens for curing, and a wide-field imaging optical path system is still kept for imaging the resolution board in real time, so that the imaging effect is ensured not to be reduced due to curing. After the ultraviolet lamp irradiates for 12 hours, the first protective sleeve and the second protective sleeve are bonded by using black glue. After the gel is well solidified, the residual solidified ultraviolet glue on the outer sleeve is scraped under a microscope, so that the lens is more attractive.

As shown in FIG. 2, the invention discloses a schematic diagram of a radial confocal endoscopic probe assembled by an assembly method of the confocal endoscopic probe. The length of the image-side working distance 4 between the optical fiber bundle 2 and the radial GRIN lens 6 is determined (near theoretical value) by a wide-field imaging system. The length of the object working distance 8 is the object distance of the radial GRIN lens 6. The Teflon protective sleeve 1 is used for protecting the main optical fiber bundle 2, the first protective sleeve 7 is used for fixing the object distance of the radial GRIN lens 6, the second protective sleeve 3 is used for fixing the image distance between the radial GRIN lens 6 and the optical fiber bundle, and the black glue 5 is used for bonding the first protective sleeve and the second protective sleeve. The method for assembling the confocal probe of the present invention firstly fixes the object distance of the front GRIN lens 6, and the first protective sleeve 7 protects the radial GRIN lens 6, fixes the object distance of the radial GRIN lens 6, and plays a role of shading. The fixing of the image distance between the optical fiber bundle 2 and the radial GRIN lens 6 is then carried out, and the image distance is fixed and the shading function is carried out while the protection is also carried out by using the second protective sleeve 3.

The GRIN lens is self-focusing lens of NEM-050-06-08-520-DS type of Grin Tech, and the selected fiber bundle is FIGH-30-650S type fiber bundle of Fujikura (rattan warehouse) of Japan. The image transmission optical fiber bundle comprises 30000 few-mode optical fibers, each of the few-mode optical fibers can be regarded as a detector pixel for receiving light intensity information, the detector pixels are arranged in the optical fiber bundle in a hexagonal distribution mode, the few-mode optical fibers have good insulating properties, crosstalk does not exist among the transmitted light intensity information, and input image information can be well transmitted from an input end to an output end. In order to ensure good imaging effect, the distance between the rear end of the optical fiber bundle and the front end of the self-focusing lens is 80 μm after the assembly is completed, and meanwhile, in order to facilitate the subsequent in-vivo medical biological experiment, the distance between the front end of the first protective sleeve 7 and the rear end of the GRIN lens is ensured to be the object distance of the GRIN lens when the length of the first protective sleeve 7 is designed, so that the lens only needs to be propped against the surface of a sample for imaging when in use.

However, in practical use, since the fiber bundle confocal endoscope needs to image a fluorescent sample, and the outer wall is cured by using ultraviolet glue alone, a fluorescent solution is led to permeate between the fiber bundle 2 and the radial GRIN lens 6, so that strong noise interference is caused during fluorescent imaging. The whole protective sleeve shell is designed into a multi-section structure, each section of protective sleeve structure is connected with the inner wall of the GRIN lens by ultraviolet glue, and the sections of the protective sleeve are bonded by the black glue 5, so that penetration of fluorescent solution can be well prevented, and the positions of the optical fiber bundle 2 and the radial GRIN lens 6 in the lens can be well matched for adjustment and assembly.

As shown in FIG. 3, the invention discloses a schematic diagram of a lateral confocal endoscopic probe assembled by the assembly method of the confocal endoscopic probe. The GRIN lens in the endoscope probe is a lateral GRIN lens 9, and the optical signal focusing point is located on the side of the lens top reflecting mechanism, namely the upper side in the figure. During assembly, the relative positions of the lateral GRIN lens 9 and the third protective sleeve 10 are measured and fixed, and the distance between the upper side of the lateral GRIN lens 9 and the upper side of the third protective sleeve 10 is the object working distance 8. When in use, the upper side of the third protective sleeve 10 is tightly attached to an object, so that confocal microscopic imaging of the surface of the object is realized. The relative positions of the optical fiber bundle 2 and the lateral GRIN lens 9 are fixed through the first protective sleeve 3, and the distance between the two is the working distance of the image space. The stainless steel protective sleeves at the two ends are bonded by using the black glue 5, so that the effect of sealing and isolating external optical noise is realized. And finally, performing appearance modification on the assembled lateral confocal inner snoop head.

As shown in fig. 4, the present invention discloses a schematic assembly of a radial GRIN lens in a radial confocal endo-head assembled by the method of the present invention. Before assembly begins, all stainless steel protective sleeves, namely stainless steel pipes, are required to be cleaned by ultrasonic, and the inner walls of the stainless steel pipes are subjected to smooth treatment by taps with proper sizes. After repeating the above operations a new tap was used to test the inside diameter size not less than 0.8 mm and the outside diameter size not greater than 1 mm. After the inspection is finished, the end face of the stainless steel pipe is ground by using sand paper, and the wall thickness of the stainless steel pipe is only 0.1 mm, so that the holding force is required to be controlled during operation to prevent the stainless steel pipe from deforming, and finally the processed stainless steel pipe is placed under a stereoscopic microscope for observation, so that the next operation can be performed after the end face and the inner wall are ensured to be in good states.

Next, a first protective sleeve 7 is applied to the outside of the radial GRIN lens to ensure that its object distance is the object working distance 8. The radial GRIN lens 6 is first fixed to the tool holder 13.

Then the fixture 13 is fixed on the lower five-dimensional adjusting frame 14 and is placed in the mirror positioner. The parallel flat crystal 12 is fixed on the upper five-dimensional adjusting frame 11 and is placed in a mirror surface positioning instrument, so that the center of the parallel flat crystal 12 and the radial GRIN lens 6 on the fixture 13 are positioned on the same vertical line as much as possible. The mirror localizer measures the center thickness of all optical elements in the optical system and the air gap between the individual lenses with high accuracy in a low coherence interference manner. The mirror surface positioning instrument used in the embodiment has the measurement precision of +/-1 mu m and the repetition precision of +/-0.5 mu m, and can well ensure the object space working distance 8 of the GRIN lens.

When the assembly is started, the whole structure is kept horizontal by adjusting the two five-dimensional adjusting frames. A first protective sleeve 7 is placed over the radial GRIN lens 6. Then the lower five-dimensional adjusting frame 14 is adjusted to continuously move up the fixture 13 loaded with the radial GRIN lens 6, the upper surface of the radial GRIN lens 6 is continuously close to the parallel flat crystal 12, the mirror surface positioning instrument is used for measuring the air gap between the radial GRIN lens 6 and the parallel flat crystal 12 repeatedly during the process, finally the distance between the radial GRIN lens and the fixture reaches the object working distance 8, the first protective cover 7 is lifted up after the measured data are stable for enabling the upper end surface of the first protective cover 7 to be in close contact with the parallel flat crystal 12, at the moment, ultraviolet glue is smeared at the joint below the first protective cover 7 and the radial GRIN lens 6, the ultraviolet glue is solidified for three minutes by using an ultraviolet lamp, the radial GRIN lens 6 with the first protective cover 7 is taken down, and the bonding effect is solidified by irradiation for three hours. The assembly of the radial GRIN lens in the confocal endoscopic head is now complete.

As shown in fig. 5, the present invention discloses a schematic diagram of the assembly of GRIN lenses in a lateral confocal endoscopic probe assembled by the method of the present invention. Before the assembly starts, all the protective sleeves made of stainless steel, namely, the stainless steel pipes, are subjected to the same operation treatment as in fig. 4 for the second protective sleeve. The third protective sleeve 10 is manufactured by selecting stainless steel with a thickness not greater than 1mm, cutting a rectangle with a proper size, folding the rectangle stainless steel into a U shape along a long side, enabling the rectangle stainless steel to perfectly fit with the peripheral shape of the lateral GRIN lens 9, enabling the U-shaped opening to face an imaging direction, enabling the U-shaped side in the direction to be slightly longer, and fixing the object space working distance 8 of the lateral GRIN lens 9. And then the end face of the third protective sleeve 10 is ground by using sand paper, the holding force is controlled during operation, deformation is prevented, and finally the treated third protective sleeve 10 is placed under a stereoscopic microscope for observation, so that the next operation can be performed after the good state is ensured.

Next, the lateral GRIN lens 9 is fixed on the tool jig 13, and then the tool jig 13 is fixed on the lower five-dimensional adjustment frame 14 and placed in the mirror positioner. The parallel flat crystals 12 are vertically fixed on the upper five-dimensional adjusting frame 11 and are placed in a mirror surface positioning instrument. The mirror localizer measures the center thickness of all optical elements in the optical system and the air gap between the individual lenses with high accuracy in a low coherence interference manner. The mirror surface positioning instrument selected in the embodiment has the measurement precision reaching +/-1 mu m and the repetition precision reaching +/-0.5 mu m, and can well ensure the object space working distance 8 of the lateral GRIN lens 9. The third protective sheath 10 is fixed to another five-dimensional adjustment frame so as to maintain the same vertical height as the tip of the lateral GRIN lens 9.

The entire structure is kept horizontal by adjusting the lower five-dimensional adjustment frame 14 when the assembly is started. The lower five-dimensional adjusting frame 14 is adjusted to continuously horizontally and rightwards move the fixture 13 for loading the lateral GRIN lens 9, the right surface of the lateral GRIN lens 9 is continuously close to the parallel flat crystal 12, the mirror surface positioning instrument is used for measuring the air gap between the lateral GRIN lens 9 and the fixture, the distance between the lateral GRIN lens and the fixture reaches the object working distance 8, the third protective sleeve 10 is rightwards moved after the measured data are stable for a plurality of times, the right end face (U-shaped opening) of the third protective sleeve 10 is tightly contacted with the parallel flat crystal 12, at the moment, a certain ultraviolet glue is smeared at the joint of the third protective sleeve 10 and the lateral GRIN lens 9, the ultraviolet glue is solidified for three minutes by using an ultraviolet lamp, the lateral GRIN lens 9 with the third protective sleeve 10 is taken down, and the bonding effect is strengthened by irradiation for three hours under the ultraviolet lamp. The assembly of the lateral GRIN lens 9 in the confocal endoscopic probe is now completed.

As shown in fig. 6, the present invention discloses an assembled ranging schematic diagram of GRIN lenses in confocal endoscopic probes of the method of the present invention. The optical principle of the mirror surface positioning instrument is a Michelson interferometer adopting a short coherent light source, the position of a reference mirror can be precisely moved, and interference can only occur when the optical path length of a measuring arm of the interferometer is equal to that of a reference arm. Thus, by monitoring the movement of the reference mirror, the position of the mirror under test can be measured.

The distance measurement principle is as follows: the short coherent light source 15 emits a short coherent light beam, the short coherent light beam is split into two short coherent light beams through the coupler 17, the two short coherent light beams are focused on the measuring arm and the reference arm through the collimator 18 respectively, and in the measuring arm section, the short coherent light beams are reflected by the surfaces of the parallel flat crystal 19 and the GRIN lens 20 respectively to generate two reflected light beams R1 and R2; in the reference arm section, the short coherent beam is delayed by a scannable reference mirror 21 and reflected off. The reflected light beams are returned to the coupler 17 through the optical signal transmission path 16, and the light beams reflected by the scannable reference mirror 21 interfere with the R1 and R2 light beams respectively to generate two interference signals, and the two interference signals are converted into electric signals through the photodiode 22 and then displayed by the display. By adjusting the position of the scannable reference mirror 21 on the optical path, the optical signal is delayed and regulated, and two positions where the two interference signals respectively have maximum values are regulated and regulated, and the difference between the positions of the scannable reference mirror 21 on the optical path corresponding to the two-pole positions is the optical distance of the distance between the parallel flat crystal 19 and the GRIN lens 20. The optical pitch divided by the refractive index of the pitch medium is the actual pitch. I.e. the distance between the parallel flat crystal 19 and the GRIN lens 20 can be calculated by analysis of the two interference signals 23.

As shown in FIG. 7, the invention discloses a radial resolution plate wide field imaging ranging and testing device diagram assembled by the method. After the object working distance 8 is fixed, it is necessary to ensure that the image distance between the image surface of the radial GRIN lens 6 and the optical fiber bundle 2 can be formed into a clear image. At this time, a second protective sleeve 3 with a length of 10 a mm is sleeved on the other end of the radial GRIN lens 6 provided with the first protective sleeve 7 with a limiting function, and the inner diameter of the second protective sleeve is 0.8 mm, the outer diameter of the second protective sleeve is 1mm, so that the optical fiber bundle 2 can be conveniently inserted into the second sleeve 7 for fixing the position. The radial GRIN lens 6 secured in the first protective sleeve 7 is then re-secured in the tooling fixture and the fiber bundle 2 is also secured with the fixture 27. In the course of fixing the image distance, the position of the optical fiber bundle 8 is fixed by means of wide-field imaging of the resolution plate 38 without the aid of a mirror positioner.

The radial GRIN lens 6 and the first protective sleeve 7 are fixed to a fixture fixed to a three-dimensional displacement table. A resolution plate 28 and an LED lamp 29 are disposed at the rear end of the first protective sleeve 7, an objective lens 26, a field lens 25 and a CCD24 are disposed at the SMA interface (left) end of the optical fiber bundle 2, and the relative position and angle of the SMA interface and the objective lens 26 are adjusted to make a hexagonal honeycomb structure clearly visible on the CCD24, so that the end face of the optical fiber bundle 2 is considered to be located on the focal plane of the objective lens 26. The optical fiber bundle 2 is fixed in a clamp 27, and the clamp 27 is fixed on a five-dimensional adjusting frame and can move along the axial direction. The LED lamp 29 was turned on, a small amount of deionized water was dropped between the resolution plate 28 and the radial GRIN lens 6, and the imaging effect of the resolution plate 28 was observed with the CCD 24. The distance between the cores of the bundle 2 is about 3.5 μm and the magnification of the radial GRIN lens 6 is 1:2.6, so the theoretical resolution of the bundle confocal lens is about 1.35 μm. The optical fiber bundle 2 is then moved continuously in the axial direction to adjust the distance between the optical fiber bundle 2 and the radial GRIN lens 6 in the second sleeve 7, so that the imaging of the resolution plate reaches the theoretical effect value as much as possible.

Then, ultraviolet glue is dripped into the joint of the second protective sleeve 3 and the radial GRIN lens 6 for curing, and the optical path system of wide-field imaging is still kept for imaging the resolution board 28 in real time, so that the imaging effect is not reduced due to curing. After 12 hours of irradiation by the ultraviolet lamp, the stainless steel protective sleeves at the two ends are bonded by using the black glue 5. After the gel is well solidified, the residual solidified ultraviolet glue on the outer sleeve is scraped under a microscope, so that the lens is more attractive. The diameter of the finally assembled confocal probe is about 1mm, and the confocal probe can be easily inserted into a working channel of a commercial electronic endoscope for cooperation.

As shown in FIG. 8, the invention discloses a lateral resolution plate wide field imaging ranging and testing device diagram assembled by the method. After the object working distance 8 is fixed, it is necessary to ensure that the image distance between the image plane of the lateral GRIN lens 9 and the optical fiber bundle 2 can be made clear. At this point, the second protective sleeve 3 is sleeved outside the other end of the lateral GRIN lens 9 provided with the third protective sleeve 10 with a limiting function. The lateral GRIN lens 9 secured in the third protective sleeve 10 is then re-secured in the tooling fixture and the fiber bundle 2 is also secured with the fixture 27. In the course of fixing the image distance, the position of the optical fiber bundle 8 is fixed by means of wide-field imaging of the resolution plate 28 without the aid of a mirror positioner. The operation of positioning the end face of the optical fiber bundle 2 on the focal plane of the objective lens 26 and the operation of measuring the image-side working distance between the optical fiber bundle and the lateral GRIN lens 9 are the same as the operation steps in fig. 7. The hexagonal honeycomb structure is clearly visible on the CCD29 and the resolution plate is imaged to the theoretical effect value as much as possible.

Then, ultraviolet glue is dripped into the joint of the second protective sleeve 3 and the lateral GRIN lens 9 for curing, and the optical path system of wide-field imaging is still kept for imaging the resolution plate 38 in real time, so that the imaging effect is not reduced due to curing. After the ultraviolet lamp irradiates for 12 hours, the black glue 5 is used for bonding the stainless steel protective sleeves at the two ends, and particularly, the third stainless steel sleeve needs to be tightly bonded. After the gel is well solidified, the residual solidified ultraviolet glue on the outer sleeve is scraped under a microscope, so that the lens is more attractive. The diameter of the finally assembled confocal probe is about 1mm, and the confocal probe can be easily inserted into a working channel of a commercial electronic endoscope for cooperation.

As shown in FIG. 9, the present invention discloses a graph of the imaging effect of a confocal endo-snoop head assembled by the method of the present invention. Fig. 9 (a) shows that the hexagonal honeycomb structure appears clearly on the CCD, and the end face of the optical fiber bundle is considered to be located on the focal plane of the objective lens at this time. When the resolution plate 28 is imaged in real time using the optical path system for wide-field imaging, a clear line pair pattern on the resolution plate 28 is displayed ((b) in fig. 9), and it can be seen from the figure that the limit area of clear imaging of the wide-field resolution plate is between the eighth group of the fourth line pair to the eighth group of the fifth line pair.

As shown in FIG. 10, the invention discloses a table for judging the imaging effect of the confocal endoscopic probe assembled by the method of the invention. Fig. 10 (a) is a positive image of a resolution plate used in the wide-field imaging ranging and testing of the resolution plate, the numbers above the line pairs are "the number of groups", the numbers on the left and right sides of the line pairs are "the number", and the distance between a certain line pair of a certain group is fixed, which can be determined by referring to the line pair table of the resolution plate per millimeter (fig. 10 (b)). Therefore, a certain group of line pairs can be clearly distinguished in a limited way by using the confocal probe, and the resolution can be judged. As can be seen in the resolution plate imaging diagram of (b) in fig. 9, the area where the wide-field resolution plate is clearly imaged at the limit is between the eighth group of fourth line pairs and the eighth group of fifth line pairs, and the resolution of the resolution plate of (b) in fig. 10 is 362 lp/mm to 406 lp/mm, namely 1.38 μm to 1.23 μm, according to the theoretical calculation result by looking up the resolution plate per millimeter line pair table.

Corresponding to the embodiment of the method for assembling the confocal endoscopic probe, the invention also provides an embodiment of an assembling device of the confocal endoscopic probe.

An apparatus for assembling a confocal endoscopic probe, comprising:

Preferably, the device further comprises a calibration module for calibrating the imaging effect of the assembled confocal endoscopic probe; the calibration module is a resolution plate wide field imaging device.

The implementation process of the functions and roles of each unit in the above device is specifically shown in the implementation process of the corresponding steps in the above method, and will not be described herein again.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary or exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims

1. A method of assembling a confocal endoscopic probe, comprising:

step four: sequentially placing the optical fiber bundle and the other end of the GRIN lens into a second protective sleeve; measuring and determining an image space working distance between the GRIN lens and the end face of the optical fiber bundle by using a resolution plate wide field imaging device, and gluing, solidifying and fixing relative positions in the measuring process to complete the assembly of the confocal endoscopic probe;

wherein, the assembly quality that the assembly process adopted includes:

2. The method according to claim 1, wherein in the first step, the parallel flat crystals and the tool fixture for clamping the GRIN lens are loaded by an adjusting device, and the adjusting device is used for controlling and adjusting the relative distance between the parallel flat crystals and the GRIN lens.

3. The method of claim 2, wherein the adjustment device is a three-dimensional adjustment frame, a four-dimensional adjustment frame, a five-dimensional adjustment frame.

4. The method of claim 2, wherein the material used for the clamping portion of the tool clamp is teflon material.

5. The method according to claim 2, wherein the tool holder is manufactured by an additive or subtractive method.

6. The method of claim 1, wherein the mirror locator is a michelson interferometer with accurate positioning function, a microscopic measuring light path.

7. The method of claim 1, wherein the GRIN lens is a radial GRIN lens or a lateral GRIN lens.

8. The method of claim 1, wherein the first protective sleeve and the second protective sleeve are made of stainless steel.

9. The method of claim 1, further comprising a calibration module for calibrating the imaging effect of the assembled confocal endoscopic probe; the calibration module is a resolution plate wide field imaging device.