Adjustable lens driven by surface acoustic wave and optical system
Through the adjustable lens driven by surface acoustic waves, the optical characteristics of the fluid lens are modulated by IDT array, which solves the problems of slow response speed and high energy consumption of traditional lenses, and achieves the improvement of fast beam regulation and dynamic focus capabilities.
Patent Information
- Application Number
- CN202510628792.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-15
- Publication Date
- 2025-06-27
AI Technical Summary
Traditional lenses have defects in response speed and energy consumption, which are difficult to quickly regulate the beam, and have poor dynamic focus capabilities, resulting in slow response time and difficult to meet the needs of rapidly changing optical conditions.
Using adjustable lenses driven by surface acoustic waves, including piezoelectric substrates, fluid lenses and IDT arrays, modulate the focus capability and beam propagation characteristics of the fluid lenses to quickly adjust the beam by adjusting the integrated surface acoustic waves generated by the IDT array.
Achieve rapid beam regulation and improved dynamic focus capabilities, reduce system complexity and energy consumption, is suitable for high-frequency applications, and reduces maintenance and calibration requirements.
Smart Images
Figure CN120214985A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of tunable optical lenses, and particularly to a surface acoustic wave-driven tunable lens and an optical system. Background Art
[0002] With the growing demand for optical technology in society, traditional lens adjustment methods have gradually shown defects such as slow response speed and insufficient adjustment accuracy. For example, lens adjustment based on mechanical movement requires physical displacement and is difficult to achieve rapid switching, while electric field-driven lenses often require high voltages, resulting in complex equipment and high energy consumption.
[0003] Traditional lenses have many limitations in optical applications, especially in terms of response speed and energy consumption. Traditional lenses need to be regulated by the transmission of mechanical components, and thus it is difficult to rapidly regulate the light beam. Moreover, the dynamic focusing ability of traditional lenses is poor, resulting in a slow response time and difficulty in meeting the requirements under rapidly changing optical conditions. Using mechanical components to regulate the light beam not only increases the complexity and failure rate of the entire optical system, increases the weight and volume, but also consumes more energy, limiting the use of traditional lenses in high-frequency applications. In addition, due to wear of mechanical components and aging of optical elements in traditional lens systems, regular maintenance and calibration are required, increasing the operating cost and technical requirements.
[0004] To solve the above problems, this application provides a surface acoustic wave-driven tunable lens and an optical system. Summary of the Invention
[0005] An embodiment of this application provides a surface acoustic wave-driven tunable lens for regulating a light beam.
[0006] In a first aspect, an embodiment of this application provides a surface acoustic wave-driven tunable lens, including a piezoelectric substrate, a fluid lens, and an IDT array;
[0007] The IDT array is disposed on the piezoelectric substrate, and the IDT array is used to generate a synthetic surface acoustic wave on the surface of the piezoelectric substrate;
[0008] The fluid lens is disposed on the piezoelectric substrate, and the fluid lens generates corresponding optical properties under the action of the synthetic surface acoustic wave.
[0009] In a feasible implementation manner, the IDT array includes a plurality of IDT units spaced on the piezoelectric substrate, and the surface acoustic waves generated by each IDT unit form the synthetic surface acoustic wave after interference and superposition.
[0010] In a feasible implementation manner, the IDT array includes two IDT units, the two IDT units are arranged oppositely, and the fluid lens is arranged between the two IDT units;
[0011] and / or, the two IDT units are arranged at an included angle of 15°;
[0012] and / or, the two IDT units are arranged at an included angle of 30°;
[0013] and / or, the two IDT units are arranged at an included angle of 45°;
[0014] and / or, the two IDT units are arranged at an included angle of 60°;
[0015] and / or, the two IDT units are arranged at an included angle of 75°;
[0016] and / or, the two IDT units are arranged at an included angle of 90°.
[0017] In a feasible implementation manner, the adjustable lens further includes a reflection grating, the reflection grating is arranged on the piezoelectric substrate, and the reflection grating is used for reflecting the surface acoustic wave.
[0018] In a feasible implementation manner, the piezoelectric substrate is configured as a 128° Y-Z cut LiNbO3 material.
[0019] In a feasible implementation manner, a 200 nm aluminum layer is arranged on the surface of the piezoelectric substrate.
[0020] In a feasible implementation manner, the surface roughness Ra of the piezoelectric substrate is ≤ 0.3 nm.
[0021] In a feasible implementation manner, the frequency of the surface acoustic wave is less than or equal to 6 GHz.
[0022] In a feasible implementation manner, the material of the surface layer of the fluid lens is a transparent optical material; the inside of the surface layer is filled with an optical liquid, and the ratio of the thickness of the optical liquid to the wavelength of the combined surface acoustic wave ranges from 0:1 to 99:1.
[0023] In a second aspect, an embodiment of the present application provides an optical system, including the surface acoustic wave-driven adjustable lens as described in the first aspect.
[0024] In a first aspect, an embodiment of the present application provides a surface acoustic wave-driven tunable lens, which includes a piezoelectric substrate, a fluid lens, and an IDT array. Among them, the IDT array is disposed on the piezoelectric substrate, and the IDT array is configured to generate a synthetic surface acoustic wave on the surface of the piezoelectric substrate. The fluid lens is disposed on the piezoelectric substrate, and the fluid lens generates corresponding optical characteristics under the action of the synthetic surface acoustic wave. The surface acoustic wave-driven tunable lens can modulate the synthetic surface acoustic wave generated by the IDT array by adjusting the excitation signal input to the IDT array, and further adjust the focusing ability and beam propagation characteristics of the fluid lens, so as to quickly adjust the beam passing through the fluid lens.
[0025] In a second aspect, an embodiment of the present application further provides an optical system, which includes the surface acoustic wave-driven tunable lens described in the first aspect, and this tunable lens is used to adjust the beam in the system. Since this optical system includes the surface acoustic wave-driven tunable lens described in any of the above technical solutions, it has all the beneficial effects of the surface acoustic wave-driven tunable lens in any of the above technical solutions, and will not be elaborated here. Description of the Drawings
[0026] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present application and do not constitute an improper limitation to the present invention.
[0027] In the drawings:
[0028] Figure 1 is a side view of the surface acoustic wave-driven tunable lens provided by an embodiment of the present application;
[0029] Figure 2 is Figure 1 a top view of the surface acoustic wave-driven tunable lens in
[0030] Figure 3 a schematic diagram of the phase difference between two adjacent IDT units.
[0031] Description of the Reference Numerals:
[0032] 100 - piezoelectric substrate; 200 - fluid lens; 300 - IDT array; 400 - synthetic surface acoustic wave; 500 - reflection grating;
[0033] 310 - IDT unit. Detailed Embodiments
[0034] To enable those skilled in the art to better understand the technical solutions in this application, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.
[0035] In the description of the embodiments of this application, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.
[0036] In this application, unless otherwise clearly defined and limited, terms such as "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0037] In this application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.
[0038] With the growing demand for optical technology in society, the traditional lens adjustment methods gradually show defects such as slow response speed and insufficient adjustment accuracy. For example, the lens adjustment based on mechanical movement requires physical displacement and is difficult to achieve rapid switching, while the electric field-driven lens often requires a relatively high voltage, resulting in complex equipment and high energy consumption.
[0039] Traditional lenses have many limitations in optical applications, especially in terms of response speed and energy consumption. Traditional lenses need to be adjusted by the transmission of mechanical components, making it difficult to quickly adjust the light beam. Moreover, traditional lenses have poor dynamic focusing ability, resulting in a slow response time and difficulty in meeting the requirements under rapidly changing optical conditions. Adjusting the light beam using mechanical components not only increases the complexity and failure rate of the entire optical system, adds weight and volume, but also consumes more energy, limiting the use of traditional lenses in high-frequency applications. In addition, due to wear of mechanical components and aging of optical elements in traditional lens systems, regular maintenance and calibration are required, increasing the operating cost and technical requirements.
[0040] To solve the above problems, this application provides an acoustoelectric surface wave-driven tunable lens and an optical system. The following will detail the solution provided by the embodiments of this application with reference to the accompanying drawings of the specification.
[0041] Figure 1 is a side view of the acoustoelectric surface wave-driven tunable lens provided by an embodiment of this application; Figure 2 is Figure 1 the top view of the acoustoelectric surface wave-driven tunable lens in
[0042] Referring to Figure 1 and Figure 2 shown, an embodiment of this application provides an acoustoelectric surface wave-driven tunable lens, including a piezoelectric substrate, a fluid lens, and an IDT array. Among them, the IDT array is disposed on the piezoelectric substrate, and the IDT array is used to generate a synthetic acoustoelectric surface wave on the surface of the piezoelectric substrate. The fluid lens is disposed on the piezoelectric substrate, and the fluid lens generates corresponding optical characteristics under the action of the synthetic acoustoelectric surface wave. The acoustoelectric surface wave-driven tunable lens can modulate the synthetic acoustoelectric surface wave generated by the IDT array by adjusting the excitation signal input to the IDT array, thereby adjusting the focusing ability and light beam propagation characteristics of the fluid lens, and thus quickly adjusting the light beam passing through the fluid lens. It should be noted that the synthetic acoustoelectric surface wave cannot be observed. For the sake of clarity, it is marked in Figure 1 and Figure 2 for indication.
[0043] Exemplarily, the IDT array includes a plurality of spaced and independently arranged IDT units on a piezoelectric substrate. The phase difference between the IDT units is adjustable. Each IDT unit can generate surface acoustic waves. The surface acoustic waves generated by all IDT units form a combined surface acoustic wave after interference and superposition. The IDT units are inter-digital transducers, which are all fabricated by microfabrication technology and have high precision and high repeatability. By adjusting the phase and frequency of the IDT units through a programmable control circuit, surface acoustic waves with specific frequencies and phases can be generated on the surface of the piezoelectric substrate. Specifically, when a periodic excitation signal is applied to multiple IDT units, an electric field will be formed between the IDT units. Under the influence of the electric field, the piezoelectric substrate material undergoes corresponding strain, thereby forming surface acoustic waves in different directions on the surface of the piezoelectric substrate. Multiple surface acoustic waves in different directions form a combined surface acoustic wave after interference and superposition. The combined surface acoustic wave interacts with the fluid in the fluid lens to form a specific surface ripple structure, which can change the arrangement and motion state of fluid surface molecules, causing the fluid molecules to be periodically disturbed, and then changing the refractive index and light transmittance of the fluid, thereby regulating the overall optical properties of the fluid lens.
[0044] Compared with the traditional lens that adjusts optical performance through mechanical components in the prior art, this adjustable lens realizes the dynamic modulation of surface acoustic waves by precisely adjusting the geometric structure of the IDT array and the applied voltage phase, and then effectively and quickly adjusts the optical performance of the liquid lens to realize the adjustment of the passing light beam.
[0045] Exemplarily, the material of the surface layer of the fluid lens is a transparent optical material; the interior of the surface layer is filled with an optical liquid with adjustable refractive index and different viscosities, such as a fluorinated liquid. The range of the ratio of the thickness of the optical liquid to the wavelength of the combined surface acoustic wave is 0:1 - 99:1.
[0046] Exemplarily, the piezoelectric substrate is configured as a 128° Y-Z cut LiNbO3 material. The LiNbO3 material has the advantages of large electromechanical coupling coefficient, small temperature coefficient, and simple processing technology. Its unit cell structure: along the Z-axis direction of the oxygen octahedron, Nb, holes, and Li occupy in sequence. When the Nb and Li atoms move relative to the oxygen atom layer, spontaneous polarization appears, and it can generate and transmit surface acoustic waves.
[0047] In some examples, a 200nm aluminum layer is provided on the surface of the piezoelectric substrate. The surface roughness Ra of the piezoelectric substrate is ≤ 0.3nm.
[0048] Exemplarily, such as Figure 3As shown, in some examples, the IDT array includes two IDT cells, the two IDT cells are arranged oppositely, and the fluid lens is arranged between the two IDT cells. The included angle between the IDT cells is the phase difference. Exemplarily, the two IDT cells can be arranged at an included angle of 15°; that is, the phase difference between the two IDT cells is 15°. Or, the two IDT cells can be arranged at an included angle of 30°; or, the two IDT cells can be arranged at an included angle of 45°; or, the two IDT cells can be arranged at an included angle of 60°; or, the two IDT cells are arranged at an included angle of 75°; or, the two IDT cells are arranged at an included angle of 90°.
[0049] It can be understood that when the arrangement of the IDT cells in the IDT array is different, the synthesized surface acoustic wave generated by the entire IDT array is different, and further the focusing ability and beam propagation characteristics of the fluid lens, that is, the ability to adjust the beam are different. The frequency of the surface acoustic wave excited by each IDT cell is less than or equal to 6 GHz, that is, up to 6 GHz at most, so that the wavelength of the surface acoustic wave is reduced to the micron level, and the manipulation and focusing of light can be realized in a smaller space, so that the size of the tunable lens can reach the micron level, providing a good basis for the miniaturization and integration of optical devices, and enabling the tunable lens to be applicable to more complex optical systems.
[0050] As shown in FIG. 2, in some examples, the tunable lens further includes a reflection grating, the reflection grating is arranged on the piezoelectric substrate, and the reflection grating is used to reflect the surface acoustic wave excited by each IDT cell.
[0051] To better illustrate the solution provided by the embodiments of the present application, the following provides experimental data for the tunable lens of the present application.
[0052] A lithium niobate single crystal substrate (thickness 0.5 mm) cut in the 128° Y-X propagation direction is used as the piezoelectric substrate. After the surface of the piezoelectric substrate is cleaned by Ar plasma, a 200-nm aluminum layer is sputtered, and after double-sided polishing, the surface roughness Ra ≤ 0.3 nm.
[0053] IDT arrays with different periods are prepared on the surface of the piezoelectric substrate by ultraviolet lithography technology, and the electrodes adopt a double-layer metal structure, and the line width tolerance is controlled within ±50 nm.
[0054] A 5-μm-thick PDMS layer (Dow Corning Sylgard 184, mixing ratio 10:1) is spin-coated on the surface of the piezoelectric substrate, and after curing, an elastic boundary layer is formed. After vacuum degassing treatment, a fluorinated liquid HFE-7500 is injected to form an optical liquid layer with a thickness h = 3λ, and the upper and lower surfaces are sealed with 100-μm-thick optical glass to form a fluid lens to realize dynamic refractive index adjustment.
[0055] An FPGA is used to generate an adjustable RF signal with a frequency range of 0.5 - 5 MHz. The adjustable RF signal is output to each IDT unit in the IDT array through a power amplifier (Mini - Circuits ZHL - 5W - 422+).
[0056] The adjustable lens formed above is placed in a 4f optical system (f = 150 mm doublet lens). A 632.8 nm He - Ne laser is used as the laser source, and the beam diameter is expanded to 8 mm. A Beam profiler (OphirSpiricon SP928) is used to record the light intensity distribution and calculate the focal length value.
[0057] Experiment 1
[0058] Experiment purpose
[0059] Analyze the dynamic regulation effect of the phase difference of IDT units on the focusing ability of this adjustable lens.
[0060] Experiment process
[0061] Adjust the frequency of the excitation signal applied to the IDT unit to 100 MHz, and sequentially adjust the phase difference (Δφ) between two adjacent IDT units to 0°, 30°, 60°, 90°. Record the corresponding amplitudes of the fluid surface ripples and the focal lengths of the fluid lens.
[0062] Use a laser interferometer to measure the amplitude (A) and wavelength (λ) of the fluid surface ripples, and record the corresponding relationship between the phase difference and the ripple morphology.
[0063] Make a laser beam (λ = 532 nm) incident on the lens, use a CCD camera to capture the focal position, and calculate the focal length change (ΔF).
[0064] Experiment results
[0065] When Δφ = 0°, the surface ripple amplitude A = 0 nm (no wave), and the focal length F = ∞ (no focusing);
[0066] When Δφ = 30°, the surface ripple amplitude A = 50 nm, and the focal length F = 10 mm;
[0067] When Δφ = 60°, the surface ripple amplitude A = 120 nm, F = 5 mm;
[0068] When Δφ = 90°, the surface ripple amplitude A = 200 nm, F = 2.5 mm.
[0069] Experiment 2
[0070] Experiment purpose
[0071] Analyze the dynamic regulation effect of the excitation signal frequency of IDT units on the focusing ability of this adjustable lens
[0072] Experimental process
[0073] Adjust the phase difference between two adjacent IDT units to 60°, vary the frequency of the excitation signal of the IDT unit from 80 MHz to 120 MHz (step size 10 MHz), and use a high-speed camera to record the beam deflection angle.
[0074] Calculate the theoretical beam deflection angle in combination with the fluid surface ripple propagation speed (v = 3000 m / s), and calculate the error between the beam deflection angle and the theoretical beam deflection angle.
[0075] Experimental results
[0076] When the frequency of the excitation signal is 80 MHz, the beam deflection angle is 0.8°, the theoretical beam deflection angle is 0.82°, and the error is 2.4%;
[0077] When the frequency of the excitation signal is 100 MHz, the beam deflection angle is 1.2°, the theoretical beam deflection angle is 1.23°, and the error is 2.5%;
[0078] When the frequency of the excitation signal is 120 MHz, the beam deflection angle is 1.5°, the theoretical beam deflection angle is 1.64°, and the error is 8.5%;
[0079] Experiment Three
[0080] Experiment purpose
[0081] Analyze the error influence of the excitation signal frequency fluctuation of the IDT unit on the beam deflection angle (θ)
[0082] Experimental process
[0083] Adjust the phase difference between two adjacent IDT units to 60°, set the frequency of the excitation signal to 100 MHz, and introduce a ±1 MHz frequency variation.
[0084] Use a spectrum analyzer to monitor the actual frequency fluctuation range; calculate the beam deflection angle deviation (Δθ) through the spot displacement.
[0085] Experimental results
[0086] Experiment Four
[0087] Experiment purpose
[0088] Analyze the correlation between the driving voltage of the IDT unit and the amplitude of the fluid surface wave and the maximum focal length adjustment range of the adjustable lens
[0089] Experimental process
[0090] Adjust the phase difference between two adjacent IDT units to 60°, set the frequency of the excitation signal to 100 MHz, and adjust the driving voltage of the IDT unit from 5 V to 20 V with a step size of 5 V.
[0091] Measure the ratio of the amplitude of the fluid surface ripple to the driving voltage of the IDT unit, and record the minimum focal length (Fmin) of the tunable lens at the corresponding voltage.
[0092] Experimental results
[0093] When the driving voltage is 5 V, the amplitude of the fluid surface ripple is 50 nm, and the minimum focal length of the tunable lens is 10 mm;
[0094] When the driving voltage is 10 V, the amplitude of the fluid surface ripple is 100 nm, and the minimum focal length of the tunable lens is 5 mm;
[0095] When the driving voltage is 20 V, the amplitude of the fluid surface ripple is 200 nm, and the minimum focal length of the tunable lens is 2.5 mm.
[0096] Experiment Five
[0097] Experimental purpose
[0098] Analyze the linear relationship between the phase difference (Δφ) and the focal length (F) of the tunable lens, and test the response time of dynamic adjustment Experimental process
[0099] Set the frequency of the excitation signal to 100 MHz, gradually increase the phase difference between two adjacent IDT units from 0° to 180° with a step size of 30°, and record the focal length of the tunable lens after each adjustment.
[0100] Switch the phase difference between 0° and 90° at a rate of 1 kHz, and measure the time required for the focal length of the tunable lens to stabilize.
[0101] Experimental results
[0102] When the phase difference is 30°, the focal length of the tunable lens is 10 mm;
[0103] When the phase difference is 60°, the focal length of the tunable lens is 5 mm;
[0104] When the phase difference is 90°, the focal length of the tunable lens is 2.5 mm.
[0105] The focal length stabilizes within 0.8 ms after the phase switch (fluctuation < ±0.1 mm).
[0106] It is easy to understand that those skilled in the art can combine, split, and recombine the embodiments of the present application based on several embodiments provided in the present application to obtain other embodiments, and these embodiments do not exceed the protection scope of the present application.
[0107] The above specific embodiments further elaborate in detail the objectives, technical solutions and beneficial effects of the embodiments of the present application. It should be understood that the above are only specific embodiments of the embodiments of the present application and are not used to limit the protection scope of the embodiments of the present application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the technical solutions of the embodiments of the present application shall be included within the protection scope of the embodiments of the present application.
Claims
1. A surface acoustic wave driven tunable lens, characterized in that: It includes a piezoelectric substrate, a fluid lens and an IDT array; The IDT array is arranged on the piezoelectric substrate, and the IDT array is used to generate a synthetic surface acoustic wave on the surface of the piezoelectric substrate; The fluid lens is disposed on the piezoelectric substrate, and the fluid lens generates corresponding optical characteristics under the action of the integrated surface acoustic wave.
2. The surface acoustic wave driven tunable lens according to claim 1, characterized in that: The IDT array includes a plurality of IDT units spaced apart from each other on the piezoelectric substrate, and the surface acoustic wave generated by each of the IDT units is interfered and superimposed to form the integrated surface acoustic wave.
3. The surface acoustic wave driven tunable lens according to claim 2, characterized in that: The IDT array includes two IDT units, the two IDT units are arranged opposite to each other, and the fluid lens is arranged between the two IDT units; And / or, the two IDT units are arranged at an angle of 15°; And / or, the two IDT units are arranged at an angle of 30°; And / or, the two IDT units are arranged at an angle of 45°; And / or, the two IDT units are arranged at an angle of 60°; And / or, the two IDT units are arranged at an angle of 75°; And / or, the two IDT units are arranged at an angle of 90°.
4. The surface acoustic wave driven tunable lens according to claim 3, characterized in that: The tunable lens further includes a reflection grating, which is disposed on the piezoelectric substrate and is used to reflect the surface acoustic wave.
5. The surface acoustic wave driven tunable lens according to claim 1, characterized in that: The piezoelectric substrate is configured as a 128° YZ tangential LiNbO 3 material.
6. The surface acoustic wave driven tunable lens according to claim 5, characterized in that: The surface of the piezoelectric substrate is provided with a 200 nm aluminum layer.
7. The surface acoustic wave driven tunable lens according to claim 5, characterized in that: The surface roughness of the piezoelectric substrate Ra is less than or equal to 0.3 nm.
8. The surface acoustic wave driven tunable lens according to claim 2, characterized in that: The frequency of the surface acoustic wave is less than or equal to 6 GHz.
9. The surface acoustic wave driven tunable lens according to claim 1, characterized in that: The surface layer of the fluid lens is made of transparent optical material; the interior of the surface layer is filled with optical liquid, and the ratio of the thickness of the optical liquid to the wavelength of the integrated surface acoustic wave is in the range of 0:1-99:
1.
10. An optical system, characterized in that: A surface acoustic wave driven tunable lens comprising the method according to any one of claims 1 to 9.