Optical fiber nonlinear microscopy scanner and method of making same

Abstract

The application discloses an optical fiber nonlinear microscopic imaging scanner and a preparation method thereof. The preparation method comprises the following steps: bonding a first piezoelectric sheet, a second piezoelectric sheet, a third piezoelectric sheet and a fourth piezoelectric sheet with a rectangular core mold respectively, and performing limiting and preliminary fixing; coating glass powder slurry at the joint surfaces between adjacent piezoelectric pads in the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet and the fourth piezoelectric sheet, and performing sintering and melting on the glass powder slurry to form a glass solidified adhesive layer connecting the adjacent piezoelectric sheets; removing the rectangular core mold, connecting the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet and the fourth piezoelectric sheet to form a piezoelectric square tube preform, and cutting the piezoelectric square tube preform into a piezoelectric square tube; and forming a stable connection between an air-core anti-resonance optical fiber, an optical fiber glass ferrule and the piezoelectric square tube.

Description

Technical Field

[0001] This invention relates to the field of nonlinear optical imaging and fiber optic scanning technology, and in particular to a fiber optic nonlinear microscopic imaging scanner and its fabrication method. Background Technology

[0002] Nonlinear optical imaging technology, due to its advantages such as chemical specificity and label-free imaging, has been widely used in the study of the structure and function of living organisms. In this type of imaging system, the scanner is a key component that determines core parameters such as imaging field of view, resolution, and frame rate. Piezoelectric ceramic scanners are a commonly used core actuator in current fiber optic scanning imaging systems, and their typical structures are circular and square tubes.

[0003] However, for tiny sizes, the manufacturing process is extremely difficult and the manufacturing flexibility is poor. Four piezoelectric ceramic sheets are bonded together to form a square tube. An optical fiber is fixed inside the square tube through an optical fiber glass ferrule. By applying a driving voltage to the piezoelectric ceramic sheets, the square tube is bent and deformed, which drives the optical fiber to perform scanning.

[0004] Currently, epoxy resin-based organic adhesives are commonly used to bond four piezoelectric ceramic sheets. However, in practical applications, this organic adhesive bonding method has been found to have the following prominent problems:

[0005] First, it has poor long-term stability. Epoxy resin adhesives undergo continuous creep after curing, and their mechanical properties change over time. Under continuous stress, the adhesive layer will produce slow additional deformation, causing the overall mechanical boundary conditions of the piezoelectric square tube to drift, ultimately resulting in a significant change in the scanning trajectory of the optical fiber over time—even under the same driving voltage, the scanning range will show significant differences.

[0006] Secondly, the consistency of the adhesive layer is difficult to guarantee. During the manual bonding process, it is difficult to ensure that the thickness and uniformity of the adhesive layer between the four ceramic pieces are completely consistent. This asymmetry will cause differences in the mechanical resonance frequencies of the square tube in the X and Y axes, causing the synthesized scanning trajectory to deviate from a perfect circle.

[0007] Third, the clamping condition is sensitive. Epoxy adhesive requires clamps for fixation during the curing process, but different clamping forces and positions will introduce additional stress, changing the boundary conditions of the piezoelectric square tube, and thus affecting its resonant frequency and vibration modes.

[0008] Fourth, insufficient temperature resistance. Organic adhesives soften and decompose at high temperatures, limiting the scanner's application in high-temperature environments or in subsequent processes requiring high temperatures.

[0009] Fifth, poor batch consistency. Traditional processes can only produce a single short square tube at a time, and human factors during the bonding process lead to inconsistent performance between products within the same batch.

[0010] To address the aforementioned problems, this invention proposes a novel scanner fabrication method. By stacking and assembling four long piezoelectric ceramic sheets around a rectangular core mold, coating each joint surface with glass powder slurry, and then performing stepwise melting and sintering to achieve inorganic bonding of the four ceramic sheets, a long piezoelectric square tube preform is fabricated in one step. The preform is then cut into piezoelectric square tubes of the required size as needed. This method solves the shortcomings of existing technologies from both material and process perspectives. Summary of the Invention

[0011] In view of the above problems, this application provides a fiber optic nonlinear microscopic imaging scanner and its fabrication method.

[0012] According to one aspect of the present invention, a method for fabricating a fiber optic nonlinear microscopic imaging scanner is provided, comprising: attaching a first piezoelectric sheet, a second piezoelectric sheet, a third piezoelectric sheet, and a fourth piezoelectric sheet to the bottom wall, a first side wall, a second side wall, and a top wall of a rectangular core mold, respectively; and limiting and initially fixing the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet, and the fourth piezoelectric sheet, wherein the cross-sectional dimensions of the rectangular core mold match the inner cavity dimensions of the target square tube; coating the joint surfaces between adjacent piezoelectric sheets with glass powder slurry, and... The glass powder slurry is sintered and melted to form a glass-cured adhesive layer connecting adjacent piezoelectric sheets; the rectangular core mold is removed, and the first, second, third, and fourth piezoelectric sheets are connected to form a piezoelectric square tube preform, which is then cut into piezoelectric square tubes; a hollow anti-resonant optical fiber with a sealed end face is inserted into an optical fiber glass ferrule, and the optical fiber glass ferrule is fixedly connected to the inside of the piezoelectric square tube, so that the optical fiber extends from one end of the square tube to form an optical fiber cantilever, and the hollow anti-resonant optical fiber, the optical fiber glass ferrule, and the piezoelectric square tube form a stable connection.

[0013] Optionally, in the steps of limiting and initially fixing the first, second, third, and fourth piezoelectric sheets respectively, adjacent pressure pads among the first, second, third, and fourth piezoelectric sheets are limited by L-shaped positioning blocks and fixed by pressure blocks; the L-shaped positioning block includes a vertically arranged first limiting part and a second limiting part, the first limiting part is attached to the outer wall of one of the adjacent piezoelectric sheets, and the second limiting part is attached to the outer wall of the other of the adjacent piezoelectric sheets; the pressure blocks are arranged opposite to each other on the surfaces of the rectangular core mold, and pressure is applied to the oppositely arranged pressure blocks to press and fix the corresponding L-shaped positioning blocks.

[0014] Optionally, the step of coating the joint surfaces between adjacent pressure pads in the first, second, third, and fourth piezoelectric sheets with glass powder slurry and sintering and melting the glass powder slurry includes: coating a first group of glass powder slurry at the joint surfaces between the second and fourth piezoelectric sheets and between the third and fourth piezoelectric sheets; performing a first melting and sintering of the first group of glass powder slurry to solidify it; flipping the structure after the first melting and sintering by 180°; coating a second group of glass powder slurry at the joint surfaces between the second and first piezoelectric sheets and between the third and first piezoelectric sheets; and performing a second melting and sintering of the second group of glass powder slurry to solidify it.

[0015] Optionally, the softening point of the glass powder slurry is 300℃-340℃, and the melting and sintering temperature is 360℃-380℃; the glass powder is lead-free glass powder, selected from one of phosphate-based, borate-based, or bismuth-based glass powders; the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet, and the fourth piezoelectric sheet are piezoelectric ceramic sheets with a Curie temperature of not less than 400℃.

[0016] Optionally, the first and second melt sintering processes include: heating to 250℃-350℃ at a rate of 1℃ / min-3℃ / min, holding at that temperature for 0.5 hours-1 hour to remove the adhesive; heating to 360℃-380℃, holding at that temperature for 0.5 hours-2 hours; and cooling to room temperature at a rate of 0.5℃ / min-5℃ / min.

[0017] Optionally, the coefficient of thermal expansion of the rectangular core mold is matched with the coefficients of thermal expansion of the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet, and the fourth piezoelectric sheet.

[0018] Optionally, coating the interface between adjacent piezoelectric sheets with glass powder paste includes: successively coating the glass powder paste into the gap between adjacent piezoelectric sheets, so that the glass powder paste forms a continuous and uniformly thick glass powder paste layer in the gap between adjacent piezoelectric sheets.

[0019] Optionally, the optical fiber glass ferrule and the inner wall of the piezoelectric square tube, and the hollow anti-resonant optical fiber and the optical fiber glass ferrule are bonded and fixed by coating with glass powder slurry and then sintering.

[0020] Optionally, it also includes connecting conductive wires to the inner and outer walls of the piezoelectric square tube, grounding the overall electrode on the inner wall of the piezoelectric square tube, and setting independent electrodes on the outer wall of the piezoelectric square tube respectively; the scanning control signal output by the signal processing unit is transmitted to the piezoelectric ceramic driver through the acquisition card, and the piezoelectric ceramic driver applies a driving signal to the independent electrodes on the outer wall of the piezoelectric square tube after power amplification, driving the hollow anti-resonant optical fiber to perform resonant scanning.

[0021] According to another aspect of the present invention, a fiber optic nonlinear microscopic imaging scanner prepared by the above-described method for fabricating a fiber optic nonlinear microscopic imaging scanner is provided, wherein the fiber optic nonlinear microscopic imaging scanner includes a scanning component and a driving component; the scanning component includes a piezoelectric square tube, a hollow anti-resonant optical fiber, and a fiber optic glass ferrule; the piezoelectric square tube includes a first piezoelectric element, a second piezoelectric element, a third piezoelectric element, and a fourth piezoelectric element, wherein adjacent piezoelectric elements are connected by a glass-cured adhesive layer formed by melting and sintering glass powder; the fiber optic glass ferrule is fixed inside the piezoelectric square tube; the hollow anti-resonant optical fiber passes through the fiber optic glass ferrule and is fixed therein, and the hollow anti-resonant optical fiber extends from one end of the piezoelectric square tube to form an optical fiber cantilever; the driving component includes a piezoelectric ceramic actuator disposed outside the scanner, the piezoelectric ceramic actuator applying a driving signal to the piezoelectric square tube to drive the optical fiber to perform resonant scanning.

[0022] The unexpected technical effect of this application is:

[0023] (1) High long-term stability. The use of inorganic glass powder fusion bonding instead of organic adhesive bonding eliminates creep and aging problems at the material level, ensuring constant mechanical properties over a long period and preventing the scanning trajectory from drifting over time.

[0024] (2) Good structural symmetry. Through precision assembly, the rectangular core mold is used as the positioning reference and the L-shaped positioning block is used to achieve three-way limiting, so as to achieve precise positioning and tight assembly of the four ceramic pieces. The two-axis resonance frequency is highly consistent and the scanning trajectory is closer to a perfect circle.

[0025] (3) Glass powder coating ensures the quality of the adhesive layer. Glass powder slurry is filled into the gap between the joint surfaces by coating. The number of coatings and the amount of each coating are controllable, which ensures the uniformity of the thickness and the filling density of the adhesive layer.

[0026] (4) Step-by-step sintering ensures molding accuracy. First, the two upper joint surfaces are sintered to form a U-shaped structure, and then the two lower joint surfaces are flipped and sintered, so that the bonding surfaces are arranged facing upwards each time they are fused. The molten glass powder naturally fills the joint gap under the action of gravity, which effectively avoids the loss of glass powder and the misalignment of ceramic sheets, and ensures the perpendicularity between the walls of the square tube and the overall dimensional accuracy.

[0027] (5) High process efficiency. The total melting and sintering time is only 6-8 hours, which is significantly more efficient than the step-by-step bonding process of epoxy adhesive, where each step takes more than 24 hours to cure.

[0028] (6) Good consistency. Long piezoelectric square tubes are prepared in one batch and then cut into corresponding short piezoelectric square tubes, which can ensure high consistency between batches.

[0029] (7) Good thermal stability. The inorganic glass fused bonding layer can withstand high temperature environment and is suitable for high temperature scenarios and applications that require high temperature post-processing.

[0030] (8) Full-process inorganic bonding. From the formation of square tubes between piezoelectric ceramic sheets to the fixing of optical fiber glass ferrules to square tubes and optical fibers to ferrules, the entire process adopts glass powder coating-melt bonding method, realizing the full-process inorganic integrated packaging of the scanner. Attached Figure Description

[0031] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0032] Figure 1 This is a schematic diagram of the mold assembly of the present invention, showing the placement of the base, L-shaped positioning block, piezoelectric ceramic sheet and rectangular core mold;

[0033] Figure 2 This is a cross-sectional view of the mold assembly of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of the long piezoelectric square tube preform of the present invention cut into a piezoelectric square tube;

[0035] Figure 4 This is a schematic diagram of the cable connections for a fiber optic scanner.

[0036] Figure 5 This is a schematic diagram of the overall structure of the fiber optic nonlinear microscopic imaging scanner of the present invention.

[0037] Figure label:

[0038] 1. First pressure block; 2. First L-shaped positioning block; 3. Fifth L-shaped positioning block; 4. Second L-shaped positioning block; 5. Sixth L-shaped positioning block; 6. Second rectangular core mold; 7. Third L-shaped positioning block; 8. Seventh L-shaped positioning block; 9. Fourth L-shaped positioning block; 10. Eighth L-shaped positioning block; 11. Second pressure block; 12. First piezoelectric sheet; 13. Second piezoelectric sheet; 14. Third piezoelectric sheet; 15. Fourth piezoelectric sheet; 16-19. Glass powder coating layer; 20. First rectangular core mold; 21. Fiber optic glass ferrule; 22. Fiber optic cable; 23. Nonlinear microscopic imaging excitation source; 24. Piezoelectric ceramic actuator; 25. Acquisition card; 26. Signal processing unit; 27-30. Piezoelectric ceramic sheet (piezoelectric square tube); 31. Conductive wire. Detailed Implementation

[0039] The present application will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. Furthermore, some well-known parts may not be shown.

[0040] This application may be presented in various forms, some of which will be described below.

[0041] Step 1: Select four PZT-based piezoelectric ceramic sheets, namely, the first piezoelectric sheet 12, the second piezoelectric sheet 13, the third piezoelectric sheet 14, and the fourth piezoelectric sheet 15. The first piezoelectric sheet 12 serves as the bottom wall of the piezoelectric square tube, and the second piezoelectric sheet 13 serves as the first side wall of the piezoelectric square tube (e.g., Figure 2 The first piezoelectric element 12, the second piezoelectric element 13, the third piezoelectric element 14, and the fourth piezoelectric element 15 serve as the top wall of the piezoelectric square tube. In one embodiment, the first piezoelectric element 12, the second piezoelectric element 13, the third piezoelectric element 14, and the fourth piezoelectric element 15 have the same dimensions. Each of the first piezoelectric element 12, the second piezoelectric element 13, the third piezoelectric element 14, and the fourth piezoelectric element 15 has dimensions of 500 mm × 1.25 mm × 0.4 mm and a Curie temperature of not less than 400°C. Phosphate-based P2O5-ZnO-Al2O3 lead-free glass powder is selected, with a softening point of 300°C-340°C, a sintering temperature of 360°C-380°C, and a coefficient of thermal expansion that matches that of PZT piezoelectric ceramics.

[0042] Step 2: Mix glass powder with terpineol and ethyl cellulose at a mass ratio of 70:25:5, and grind and disperse them on a grinder for 4-6 hours to prepare a glass powder slurry suitable for coating. The viscosity of the glass powder slurry is 5000cps-15000cps.

[0043] Step 3: Refer to Figure 1 and Figure 2 A first pressure block 1 with a flat surface is provided. A first set of positioning blocks and a second set of positioning blocks are placed on the surface of the first pressure block 1, and the first set of positioning blocks and the second set of positioning blocks are arranged along the length direction of the first pressure block 1. The first set of positioning blocks includes a first L-shaped positioning block 2, a second L-shaped positioning block 4, a third L-shaped positioning block 7, and a fourth L-shaped positioning block 9; the second set of positioning blocks includes a fifth L-shaped positioning block 3, a sixth L-shaped positioning block 5, a seventh L-shaped positioning block 8, and an eighth L-shaped positioning block 10. Each positioning block from the first L-shaped positioning block 2 to the eighth L-shaped positioning block 10 includes a vertically arranged first limiting part and a second limiting part.

[0044] In this step, a first L-shaped positioning block 2 and a second L-shaped positioning block 4, as well as a fifth L-shaped positioning block 3 and a sixth L-shaped positioning block 5, are placed opposite each other on the surface of the first pressure block 1. The first L-shaped positioning block 2 and the fifth L-shaped positioning block 3 are arranged along the length of the first pressure block 1, as are the second L-shaped positioning block 4 and the sixth L-shaped positioning block 5. The horizontal limiting portions of the first L-shaped positioning block 2, the second L-shaped positioning block 4, the fifth L-shaped positioning block 3, and the sixth L-shaped positioning block 5 are attached to the surface of the first pressure block 1. The vertical limiting portions of the first L-shaped positioning block 2, the second L-shaped positioning block 4, the fifth L-shaped positioning block 3, and the sixth L-shaped positioning block 5 limit the piezoelectric sheet.

[0045] The first and second sets of positioning blocks are both made of alumina ceramic, and their coefficient of thermal expansion matches that of the ceramic piezoelectric sheet.

[0046] Step 4: Place the first piezoelectric sheet 12 within the space defined by the first L-shaped positioning block 2, the second L-shaped positioning block 4, the fifth L-shaped positioning block 3, and the sixth L-shaped positioning block 5. One end of the first piezoelectric sheet 12 is attached to the horizontal limiting portion of the first L-shaped positioning block 2 and the second L-shaped positioning block 4, and the other end of the first piezoelectric sheet 12 is attached to the horizontal limiting portion of the fifth L-shaped positioning block 3 and the sixth L-shaped positioning block 5. The first piezoelectric sheet 12 serves as the bottom wall of the piezoelectric square tube.

[0047] A rectangular core mold is placed on the surface of the first piezoelectric sheet 12 away from the positioning block. In this embodiment, a first rectangular core mold 20 is placed on the first end surface of the first piezoelectric sheet 12, and a second rectangular core mold 6 is placed on the first end surface of the first piezoelectric sheet 12. Both the second rectangular core mold 6 and the first rectangular core mold 20 are made of alumina ceramic, and their cross-sectional dimensions are equal to the design dimensions of the inner cavity of the piezoelectric square tube. In this embodiment, the dimensions of the rectangular core mold are 30 mm × 1.25 mm × 1.25 mm. The sum of the lengths of the second rectangular core mold 6 and the first rectangular core mold 20 is less than the length of the first piezoelectric sheet 12, and the gap between the second rectangular core mold 6 and the first rectangular core mold 20 is the inner cavity space of the piezoelectric square tube. The four edges of the second rectangular core mold 6 and the first rectangular core mold 20 are all unground right-angled edges with an edge angle of approximately 90°, without chamfering or rounding.

[0048] Step 5: Place the second piezoelectric sheet 13 on the first side of the second rectangular core mold 6 and the first rectangular core mold 20, so that the inner side of the second piezoelectric sheet 13 is in close contact with the first side of the second rectangular core mold 6 and the first rectangular core mold 20, respectively, and the outer side of the second piezoelectric sheet 13 is in contact with the inner surface of the vertical limiting part of the first L-shaped positioning block 2 and the fifth L-shaped positioning block 3. The bottom surface of the second piezoelectric sheet 13 is flush with the bottom surface of the second rectangular core mold 6 and the first rectangular core mold 20, and a space for accommodating glass powder slurry is formed between the bottom surface of the second piezoelectric sheet 13 and the first side wall of the first piezoelectric sheet 12.

[0049] The third piezoelectric sheet 14 is placed on the second side of the second rectangular core mold 6 and the first rectangular core mold 20, so that the inner side of the third piezoelectric sheet 14 is in close contact with the second side of the second rectangular core mold 6 and the first rectangular core mold 20, respectively, and the outer side of the third piezoelectric sheet 14 is in contact with the inner surface of the vertical limiting part of the second L-shaped positioning block 4 and the sixth L-shaped positioning block 5. The bottom surface of the third piezoelectric sheet 14 is flush with the bottom surface of the second rectangular core mold 6 and the first rectangular core mold 20, and a space for accommodating glass powder slurry is formed between the bottom surface of the third piezoelectric sheet 14 and the second side wall of the first piezoelectric sheet 12.

[0050] The second piezoelectric element 13 serves as the first sidewall of the piezoelectric square tube, and the third piezoelectric element 14 serves as the second sidewall of the piezoelectric square tube.

[0051] Step 6: Place the fourth piezoelectric sheet 15 above the second rectangular core mold 6 and the first rectangular core mold 20, so that the lower surface of the fourth piezoelectric sheet 15 is in close contact with the upper surface of the second rectangular core mold 6 and the first rectangular core mold 20 respectively. A space for accommodating glass powder slurry is formed between the first side surface of the fourth piezoelectric sheet 15 and the top surface of the second piezoelectric sheet 13, and a space for accommodating glass powder slurry is formed between the second side surface of the fourth piezoelectric sheet 15 and the top surface of the third piezoelectric sheet 14.

[0052] Next, the third L-shaped positioning block 7, the fourth L-shaped positioning block 9, the seventh L-shaped positioning block 8, and the eighth L-shaped positioning block 10 are placed, wherein the horizontal limiting portion of the third L-shaped positioning block 7, the fourth L-shaped positioning block 9, the seventh L-shaped positioning block 8, and the eighth L-shaped positioning block 10 contacts the top surface of the fourth piezoelectric sheet 15, the inner surface of the vertical limiting portion of the third L-shaped positioning block 7 and the seventh L-shaped positioning block 8 contacts the outer surface of the second piezoelectric sheet 13, and the inner surface of the vertical limiting portion of the fourth L-shaped positioning block 9 and the eighth L-shaped positioning block 10 contacts the outer surface of the third piezoelectric sheet 14.

[0053] Next, a second pressure block 11 is placed above the third L-shaped positioning block 7, the fourth L-shaped positioning block 9, the seventh L-shaped positioning block 8, and the eighth L-shaped positioning block 10. The second pressure block 11 applies a downward uniform pressure, so that the third L-shaped positioning block 7, the fourth L-shaped positioning block 9, the seventh L-shaped positioning block 8, and the eighth L-shaped positioning block 10 press and fix the piezoelectric sheet from above.

[0054] In this embodiment, both the L-shaped positioning block and the pressure block are made of alumina ceramic. Thus, the first piezoelectric sheet 12, the second piezoelectric sheet 13, the third piezoelectric sheet 14, and the fourth piezoelectric sheet 15 are stacked and assembled around the second rectangular core mold 6 and the first rectangular core mold 20—combined piece by piece in the order of bottom wall, side wall, and top wall, forming a complete square tube-shaped stack. All four ceramic sheets are fully positioned in the X, Y, and Z directions.

[0055] Step 7: Apply glass powder slurry to the upper joint surface between the second piezoelectric element 13 and the fourth piezoelectric element 15 to form a glass powder stacked layer 19; apply glass powder slurry to the upper joint surface between the third piezoelectric element 14 and the fourth piezoelectric element 15 to form a glass powder stacked layer 18. Repeat the application 2-3 times to ensure a continuous and uniformly thick glass powder stacked layer within the joint surface gaps. The thickness of the glass powder stacked layer should be controlled between 80 μm and 120 μm. Place the assembled complete unit into a box-type high-temperature furnace for the first sintering. The temperature is increased to 300℃ at a rate of 2℃ / min and held for 0.5 hours to remove the adhesive, allowing terpineol and ethyl cellulose to fully decompose and volatilize. The temperature is then increased to 370℃ at a rate of 3℃ / min and held for 1 hour to melt the glass powder stack 18 and glass powder stack 19. The molten glass naturally sinks to the bottom of the joint gap under gravity and fully wets the joint surface, bonding and solidifying the upper two joint surfaces of the second piezoelectric sheet 13, the third piezoelectric sheet 14, and the fourth piezoelectric sheet 15 to form a U-shaped structure. The temperature is then cooled to room temperature at a rate of 2℃ / min.

[0056] Step 8: Rotate the cooled assembly 180° so that the first piezoelectric sheet 12 faces upward (at this time, the two bonding surfaces originally on the lower side are now facing upward). Apply glass powder slurry to the bonding surface between the first piezoelectric sheet 12 and the second piezoelectric sheet 13 to form a glass powder stack layer 17; apply glass powder slurry to the bonding surface between the first piezoelectric sheet 12 and the third piezoelectric sheet 14 to form a glass powder stack layer 16. The number of coatings and thickness control are the same as the first time. At this time, the four piezoelectric ceramic sheets remain in place in the assembly and do not need to be disassembled. Place the rotated assembly back into the box-type resistance furnace for a second sintering. The sintering temperature curve is the same as the first time. At this point, all four bonding surfaces of the first piezoelectric sheet 12, the second piezoelectric sheet 13, the third piezoelectric sheet 14, and the fourth piezoelectric sheet 15 have been bonded with glass powder, forming a complete square tubular structure.

[0057] Step 9: Remove the stacked body from the high-temperature furnace and allow it to cool to room temperature. Then, remove the second pressure block 11 and all the L-shaped positioning blocks in sequence. Since the four edges of the second rectangular core mold 6 and the first rectangular core mold 20 retain sharp right angles, the glass powder slurry does not adhere significantly to the core mold surface after melting. The second rectangular core mold 6 and the first rectangular core mold 20 can be gently pushed out from the center of both ends of the square tube to obtain a four-piece long piezoelectric square tube preform with glass fusion bonding, with a length of 500 mm.

[0058] Step 10: Refer to Figure 3 The long piezoelectric square tube preform obtained in step 9 is cut according to the target size. Figure 3 The upper part is a long piezoelectric square tube preform formed by integral melting and sintering (composed of piezoelectric ceramic sheets 12-15), and the lower part consists of multiple piezoelectric square tubes obtained after cutting (each composed of piezoelectric ceramic sheets 27-30). In this embodiment, the 500 mm long piezoelectric square tube is cut into 23 mm long piezoelectric square tube segments, resulting in 21 segments (considering cutting losses). Cutting is performed using a precision dicing machine or wire cutting to ensure that the cut end faces are flat and have good perpendicularity. All piezoelectric square tubes cut from the same long piezoelectric square tube preform have completely consistent material properties and dimensional accuracy.

[0059] Step 11: Refer to Figure 4 Conductive wires 31 are connected to the inner and outer walls of the piezoelectric square tube. The inner wall is connected as a whole electrode by copper powder conductive adhesive and grounded; the four piezoelectric ceramic plates 27-30 on the outer wall are each provided with an independent electrode.

[0060] Step 12: Insert the fiber optic glass ferrule 21 into the piezoelectric square tube. Coat the space between the outer wall of the fiber optic glass ferrule 21 and the inner wall of the piezoelectric square tube with glass powder paste. Place the tube in a high-temperature furnace and melt-sinter at 360-380℃ to fix the fiber optic glass ferrule 21 to the piezoelectric square tube. Pass the hollow-core anti-resonant fiber 22 through the fiber optic glass ferrule 21 and position it inside the fiber optic glass ferrule 21. Coat the space between the hollow-core anti-resonant fiber 22 and the fiber optic glass ferrule 21 with glass powder paste. Place the tube in a high-temperature furnace and melt-sinter at 360-380℃ to fix the hollow-core anti-resonant fiber 22 in the fiber optic glass ferrule 21. The hollow-core anti-resonant fiber 22 extends a predetermined length from the front end of the square tube to form a fiber cantilever. The rear end of the hollow-core anti-resonant fiber 22 is connected to the nonlinear microscopic imaging excitation source 23.

[0061] Step 13: Refer to Figure 5 The scanning control signal output by the signal processing unit 26 is transmitted to the piezoelectric ceramic driver 24 via the acquisition card 25. After being amplified by power, the piezoelectric ceramic driver 24 applies a driving signal to the independent electrode on the outer wall of the square tube, driving the optical fiber to perform resonant scanning.

[0062] Example 2

[0063] The difference between this embodiment and Embodiment 1 is that: the glass powder used is borate-based (B2O3-ZnO-BaO), the sintering temperature is 360℃, and the holding time is 1.5 hours; the rectangular core mold material is a high-temperature alloy. The remaining steps are the same as in Embodiment 1.

[0064] Example 3

[0065] The difference between this embodiment and Embodiment 1 is that the glass powder used is bismuth-based (Bi2O3-B2O3-ZnO), the sintering temperature is 380℃, and the holding time is 0.5 hours. The remaining steps are the same as in Embodiment 1.

[0066] In summary, the stacked low-temperature glass fusion method proposed in this invention refers to the assembly process of assembling four long piezoelectric ceramic sheets around two rectangular core molds placed at both ends, sequentially combining the bottom wall, side wall, and top wall to form a square tube structure. Using the rectangular core molds as positioning references achieves precise stacking and assembly of the four ceramic sheets. The step-by-step coating and step-by-step melting and sintering strategies effectively avoid the influence of gravity on the bonding quality, ultimately achieving high-precision fabrication of the long piezoelectric square tube preform. The long piezoelectric square tube preform fabricated in one step is cut to obtain multiple piezoelectric square tubes of uniform size, ensuring high consistency in batch products. Fiber optic glass ferrules and hollow anti-resonant fibers are assembled into the piezoelectric square tubes to obtain a fiber optic nonlinear microscopic imaging scanner with a fully inorganic bonding process. This method is highly efficient, consistent, and reliable in demolding, and is of great significance for the engineering manufacturing of nonlinear microscopic imaging scanners.

[0067] As described above, these embodiments of this application do not exhaustively cover all details, nor do they limit the application to merely the specific embodiments described. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this application, thereby enabling those skilled in the art to effectively utilize this application and its modifications. This application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for fabricating a fiber optic nonlinear microscopic imaging scanner, comprising: The first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet, and the fourth piezoelectric sheet are respectively attached to the bottom wall, the first side wall, the second side wall, and the top wall of the rectangular core mold, and the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet, and the fourth piezoelectric sheet are respectively limited and initially fixed. The cross-sectional dimensions of the rectangular core mold are matched with the inner cavity dimensions of the target square tube. Glass powder paste is applied to the joint surfaces between adjacent piezoelectric sheets in the first, second, third, and fourth piezoelectric sheets, and the glass powder paste is sintered and melted to form a glass-cured adhesive layer connecting the adjacent piezoelectric sheets. Remove the rectangular core mold, connect the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet, and the fourth piezoelectric sheet to form a piezoelectric square tube preform, and cut the piezoelectric square tube preform into a piezoelectric square tube; A hollow anti-resonant optical fiber with a sealed end face is inserted into an optical fiber glass ferrule, and the optical fiber glass ferrule is fixedly connected to the inside of the piezoelectric square tube, so that the optical fiber extends from one end of the square tube to form an optical fiber cantilever, and the hollow anti-resonant optical fiber, the optical fiber glass ferrule and the piezoelectric square tube form a stable connection.

2. The preparation method according to claim 1, wherein, In the steps of limiting and initially fixing the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet, and the fourth piezoelectric sheet respectively, the adjacent pressure pads of the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet, and the fourth piezoelectric sheet are limited by L-shaped positioning blocks and fixed by pressure blocks; The L-shaped positioning block includes a first limiting part and a second limiting part arranged vertically. The first limiting part is attached to the outer wall of one of the adjacent piezoelectric pieces, and the second limiting part is attached to the outer wall of the other adjacent piezoelectric piece. Pressure blocks are positioned opposite each other on the surfaces of the rectangular core mold, and pressure is applied to the opposing pressure blocks to press and fix the corresponding L-shaped positioning blocks.

3. The preparation method according to claim 2, wherein, The steps of coating the joint surfaces between adjacent pressure pads in the first, second, third, and fourth piezoelectric sheets with glass powder slurry and sintering and melting the glass powder slurry include: The first set of glass powder slurry is coated on the joint surface between the second piezoelectric sheet and the fourth piezoelectric sheet, and on the joint surface between the third piezoelectric sheet and the fourth piezoelectric sheet; The first batch of glass powder slurry was melted and sintered for the first time to solidify the first batch of glass powder slurry; The structure after the first melting and sintering is flipped 180°. A second set of glass powder slurry is applied to the bonding surfaces between the second piezoelectric sheet and the first piezoelectric sheet, and between the third piezoelectric sheet and the first piezoelectric sheet. The second group of glass powder slurry is subjected to a second melting and sintering process to solidify the second group of glass powder slurry.

4. The preparation method according to claim 1, wherein, The softening point of the glass powder slurry is 300℃-340℃, and the melting and sintering temperature is 360℃-380℃. The glass powder is lead-free glass powder, selected from one of phosphate-based, borate-based, or bismuth-based glass powders; The first, second, third, and fourth piezoelectric sheets are piezoelectric ceramic sheets with a Curie temperature of not less than 400°C.

5. The preparation method according to claim 1, wherein, The processes of the first melt sintering and the second melt sintering include: Heat to 250℃-350℃ at a rate of 1℃ / min-3℃ / min, hold for 0.5 hours-1 hour, and then discharge the adhesive. Heat to 360℃-380℃ and hold for 0.5 hours-2 hours; Cool to room temperature at a rate of 0.5℃ / min to 5℃ / min.

6. The preparation method according to claim 1, wherein, The coefficient of thermal expansion of the rectangular core mold is matched with the coefficients of thermal expansion of the first piezoelectric sheet, the second piezoelectric sheet, the third piezoelectric sheet, and the fourth piezoelectric sheet.

7. The preparation method according to claim 4, wherein, Coating the interface between adjacent piezoelectric elements with glass powder paste includes: successively applying glass powder paste into the gap between adjacent piezoelectric elements, so that the glass powder paste forms a continuous and uniformly thick glass powder paste layer in the gap between adjacent piezoelectric elements.

8. The preparation method according to claim 7, wherein, The optical fiber glass ferrule and the inner wall of the piezoelectric square tube, as well as the hollow anti-resonant optical fiber and the optical fiber glass ferrule, are bonded and fixed by coating with glass powder slurry and then sintering.

9. The preparation method according to claim 8, wherein, It also includes connecting conductive wires to the inner and outer walls of the piezoelectric square tube, grounding the overall electrode on the inner wall of the piezoelectric square tube, and setting independent electrodes on the outer wall of the piezoelectric square tube respectively; the scanning control signal output by the signal processing unit is transmitted to the piezoelectric ceramic driver through the acquisition card, and the piezoelectric ceramic driver applies a driving signal to the independent electrodes on the outer wall of the piezoelectric square tube after power amplification, driving the hollow anti-resonant optical fiber to perform resonant scanning.

10. A fiber optic nonlinear microscopic imaging scanner prepared by the method described in any one of claims 1 to 9, wherein, Fiber optic nonlinear microscopy scanners include scanning components and driving components; The scanning assembly includes a piezoelectric square tube, a hollow anti-resonant optical fiber, and an optical fiber glass ferrule. The piezoelectric square tube includes a first piezoelectric sheet, a second piezoelectric sheet, a third piezoelectric sheet, and a fourth piezoelectric sheet. Adjacent piezoelectric sheets among the first, second, third, and fourth piezoelectric sheets are connected by a glass-cured adhesive layer formed by melting and sintering glass powder. The optical fiber glass ferrule is fixed inside the piezoelectric square tube; The hollow anti-resonant optical fiber passes through the optical fiber glass ferrule and is fixed therein, and the hollow anti-resonant optical fiber extends from one end of the piezoelectric square tube to form an optical fiber cantilever. The driving component includes a piezoelectric ceramic driver disposed outside the scanner. The piezoelectric ceramic driver applies a driving signal to the piezoelectric square tube to drive the optical fiber to perform resonant scanning.

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