A focal length adjustable concave lens array and its adjustment method

Abstract

This application relates to a focal length adjustable concave lens array and its adjustment method, comprising a microlens array generation module and a lens focal length adjustment module. The microlens array generation module includes a microfluidic chip and a liquid inlet. The microfluidic chip has a microfluidic channel for forming a bubble lens array from dissolved gas in the liquid, and the microfluidic channel is connected to the liquid inlet. The lens focal length adjustment module includes a piezoelectric element and a signal generator. The signal generator is connected to the piezoelectric element and is used to input a frequency signal to the piezoelectric element, causing the piezoelectric element to generate a sound wave of a corresponding frequency according to the frequency signal, thereby controlling the bubble size of the bubble lens array in the microfluidic channel. This application solves the problem in related technologies where the concave lens array structure is fixed after fabrication, making it impossible to adjust the focal length in real time according to specific application requirements.

Description

Technical Field

[0001] This application relates to the field of microlens array technology, and in particular to a focal length adjustable concave lens array and its adjustment method. Background Technology

[0002] Microlens arrays, as a multifunctional optical element, are characterized by high integration and small unit size. They can perform beam shaping, light distribution, and optical focusing on incident beams, and are widely used in lighting sources, imaging sensors, displays, and photovoltaics.

[0003] Based on their shape, microlens arrays can be divided into concave lens arrays and convex lens arrays.

[0004] Current research and applications of microlens arrays mainly focus on convex lens arrays. There are also various fabrication processes for convex lens arrays, such as inkjet printing, hot melt reflow technology, chemical vapor deposition, and laser direct writing technology.

[0005] In comparison, concave lens arrays also have many applications in real life, such as high-performance street lighting, aberration adjustment, and diffusers. However, the fabrication technology of concave lens arrays is relatively simple, with only local material removal techniques such as laser ablation and wet ablation.

[0006] Moreover, the surface of concave lens arrays produced by this technology is often relatively rough, and the structure of the concave lens array is fixed after the fabrication is completed, making it impossible to adjust the focal length in real time according to specific application requirements. Summary of the Invention

[0007] This application provides a focal length adjustable concave lens array and adjustment method to solve the problem in related technologies where the structure of the concave lens array is fixed after fabrication, and the focal length cannot be adjusted in real time according to specific application requirements.

[0008] In a first aspect, a focal length-adjustable concave lens array is provided, comprising:

[0009] A microlens array generation module includes a microfluidic chip and a liquid inlet. The microfluidic chip is provided with a microfluidic channel for forming a bubble lens array of dissolved gas in the liquid. The microfluidic channel is connected to the liquid inlet.

[0010] A lens focal length adjustment module includes a piezoelectric element and a signal generator. The signal generator is connected to the piezoelectric element and is used to input a frequency signal to the piezoelectric element, so that the piezoelectric element generates a sound wave of a corresponding frequency according to the frequency signal, thereby controlling the bubble size of the bubble lens array in the microfluidic channel.

[0011] In some embodiments, the microfluidic channel includes a first cavity and a second pit array, the second pit array being located above the first cavity, the second pit array including a plurality of pits for capturing bubbles, and the pits communicating with the first cavity.

[0012] In some embodiments, the height of the first cavity layer is 100 μm, the depth of the pits is 50 μm, the array configuration of the second pit layer is a 5×4 pit array, the radius of the pits is 50 μm, and the distance between the pits is 700 μm.

[0013] In some embodiments, the liquid inlet is connected to a microfluidic pump;

[0014] And / or, the piezoelectric sheet is annular, and the microlens array generating module is located in the middle of the piezoelectric sheet;

[0015] And / or, a power amplifier is connected between the signal generator and the piezoelectric element;

[0016] And / or, the liquid flow rate entering the microfluidic channel from the liquid inlet is 1 to 2.5 μl / min.

[0017] In some embodiments, the concave lens array further includes a glass slide, and the microlens array generating module and the piezoelectric sheet are fixed on the glass slide.

[0018] In some embodiments, the microlens array generating module and the piezoelectric sheet are fixed to the glass slide by an adhesive.

[0019] In some embodiments, the adhesive is a light-curing resin.

[0020] In some embodiments, the photocurable resin is an ultraviolet-curable resin.

[0021] Secondly, a method for adjusting a focal length adjustable concave lens array as described in any of the above is provided, comprising:

[0022] Based on the target focal length and the mapping relationship between focal length and frequency and action time, the target frequency and target action time of the sound wave generated by the piezoelectric sheet are obtained.

[0023] The signal generator controls the piezoelectric element to generate sound waves at the target frequency and maintain the target duration.

[0024] In some embodiments, it further includes a step of obtaining a mapping relationship between focal length and frequency and action time, and obtaining the mapping relationship between focal length and frequency and action time includes:

[0025] By using a signal generator, the piezoelectric element is controlled to generate sound waves of different frequencies and for different durations, thereby obtaining the focal length of the bubble at different frequencies and durations.

[0026] Using focal length as the dependent variable and frequency and duration of action as independent variables, curve fitting was performed to obtain the mapping relationship between focal length and frequency and duration of action.

[0027] The beneficial effects of the technical solution provided in this application include:

[0028] The structure of this application is relatively simple, mainly including two modules: a microlens array generation module and a lens focal length adjustment module. When the liquid enters the microfluidic channel of the microfluidic chip from the liquid inlet at an appropriate speed, due to the pinning effect of surface tension, the microfluidic channel will capture and retain the dissolved gas in the liquid and make it as a bubble nucleus to form a bubble lens array, thus obtaining the microlens array.

[0029] By adjusting the frequency and power of the signal generator, a frequency signal is emitted to the piezoelectric element, causing the piezoelectric element to generate sound waves of the corresponding frequency according to the frequency signal, which in turn causes the bubbles in the bubble lens array to grow and adjust the bubble size.

[0030] As can be seen, this application utilizes microfluidic channels to capture dissolved gas in liquids to form a bubble lens array, and then uses sound waves to generate cavitation at the bubble nuclei to control the movement of the gas-liquid interface, thereby achieving real-time adjustable focal length of the concave lens array. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A schematic diagram of a focal length adjustable concave lens array provided in an embodiment of this application;

[0033] Figure 2 Cross-sectional view of a focal length adjustable concave lens array provided in an embodiment of this application;

[0034] Figure 3 A three-dimensional view of the bubble lens array provided in the embodiments of this application;

[0035] Figure 4 This is a schematic diagram of a bubble lens array with different focal lengths provided in the embodiments of this application;

[0036] Figure 5 This is a schematic diagram illustrating the effect of different frequencies on the size of the bubble lens array, provided in an embodiment of this application.

[0037] Figure 6 An image showing the imaging effect of a focal length adjustable concave lens array provided in an embodiment of this application.

[0038] In the figure: 1. Microfluidic chip; 2. Bubble lens array; 3. Piezoelectric sheet; 4. First cavity layer; 5. Second pit array layer; 6. Glass slide. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] See Figure 1 and Figure 2 As shown, this application embodiment provides a focal length adjustable concave lens array, which includes a microlens array generation module and a lens focal length adjustment module. The microlens array generation module includes a microfluidic chip 1 and a liquid inlet and a liquid outlet. The microfluidic chip 1 is provided with a microfluidic channel for forming a bubble lens array 2 from dissolved gas in the liquid. The microfluidic channel is connected to the liquid inlet and the liquid outlet. The lens focal length adjustment module includes a piezoelectric element 3 and a signal generator. The signal generator is connected to the piezoelectric element 3 and is used to input a frequency signal to the piezoelectric element 3, so that the piezoelectric element 3 generates a sound wave of a corresponding frequency according to the frequency signal, thereby controlling the bubble size of the bubble lens array 2 in the microfluidic channel.

[0041] The structure of this application is relatively simple, mainly including two modules: a microlens array generation module and a lens focal length adjustment module. When the liquid enters the microfluidic channel of the microfluidic chip 1 from the liquid inlet at an appropriate speed, the microfluidic channel will capture and retain the dissolved gas in the liquid due to the pinning effect of surface tension, and make it as a bubble nucleus to form a bubble lens array 2, thus obtaining the microlens array.

[0042] By adjusting the frequency and power of the signal generator, a frequency signal is emitted to the piezoelectric element 3, causing the piezoelectric element 3 to generate sound waves of a corresponding frequency according to the frequency signal, thereby causing the bubbles in the bubble lens array 2 to grow and adjusting the bubble size.

[0043] As can be seen, this application utilizes microfluidic channels to capture dissolved gas in liquids to form a bubble lens array, and then uses sound waves to generate cavitation at the bubble nuclei to control the movement of the gas-liquid interface, thereby achieving real-time adjustable focal length of the concave lens array.

[0044] It should be noted that the liquid mentioned above can be water or other liquids, and the dissolved gas can be air or other gases.

[0045] It should be noted that the resonant frequency of the piezoelectric element 3 can be selected according to actual needs. For example, the resonant frequency of the piezoelectric element 3 can be 1MHz / 2MHz / 3MHz.

[0046] To achieve gas capture in a liquid to form a bubble lens array, in some preferred embodiments, see [link to relevant documentation]. Figure 2 As shown, the microfluidic channel includes a first cavity 4 and a second pit array 5. The second pit array 5 is located above the first cavity 4 and includes a number of pits for capturing bubbles, and the pits are connected to the first cavity 4.

[0047] When the liquid enters the microfluidic channel, the pit array will retain the dissolved gas in the liquid and form a bubble lens array due to the pinning effect of surface tension.

[0048] It should be noted that in this embodiment, the microfluidic chip 1 is made of the organic material polydimethylsiloxane (PDMS). The specific fabrication method is as follows: the shape of the first cavity 4 and the second pit array 5 in the microfluidic channel is drawn using software. Masks are made according to the shape. Then, the pattern is developed onto the silicon wafer by ultraviolet lithography to obtain the silicon wafer mold of the microfluidic channel. Subsequently, unsolidified PDMS is poured onto the silicon wafer mold and solidified by baking at 75°C for 1 hour to obtain the microfluidic chip 1.

[0049] It should be noted that there are multiple options for the shape of the recess. For example, the recess can be cylindrical or hemispherical.

[0050] The size of the microfluidic channel can be determined according to actual needs. For example, the height of the first cavity 4 is 100μm and the depth of the pit is 50μm. The array of the second pit array 5 is a 5×4 pit array with a pit radius of 50μm and a distance of 700μm between pits.

[0051] To facilitate smooth liquid flow, a microfluidic pump is connected to the liquid inlet. This pump not only improves liquid flow but also allows for control of the flow rate. For example, the liquid flow rate entering the microfluidic channel from the inlet is 1–2.5 μl / min to prevent the formation of air bubbles or air pockets outside the recess. Preferably, the liquid flow rate entering the microfluidic channel from the inlet is 2 μl / min.

[0052] The shape of the piezoelectric element 3 is available in multiple options and can be determined according to actual needs. For example, see [example]. Figure 1As shown, the piezoelectric element 3 is annular, and the microlens array generation module is located in the middle of the piezoelectric element 3. The annular shape can be square or circular, but a circular shape is preferred. This can minimize the difference in sound intensity caused by the different distances of different pits from the piezoelectric element, making the concave lens array more uniform.

[0053] In order to adjust the output power of the signal generator, in some preferred embodiments, a power amplifier is connected between the signal generator and the piezoelectric element 3; specifically, the piezoelectric element 3 is connected to the power amplifier through the positive signal input terminal and the negative signal input terminal, and the power amplifier is then connected to the signal generator.

[0054] See Figure 1 As shown, in some preferred embodiments, the concave lens array further includes a glass slide 6, and the microlens array generating module and the piezoelectric sheet 3 are fixed on the glass slide 6.

[0055] The microlens array generating module and the piezoelectric element 3 are fixed to the glass slide 6 with an adhesive. Specifically, the adhesive can be a photocurable resin or glue.

[0056] For example, the light-curing resin is a UV-curing resin.

[0057] Alternatively, the microlens array generation module and the piezoelectric element 3 can be coupled together via silicone oil.

[0058] This application embodiment also provides an adjustment method for any of the above-mentioned focal length adjustable concave lens arrays, which includes the following steps:

[0059] 101: Based on the target focal length and the mapping relationship between focal length and frequency and action time, obtain the target frequency and target action time of the sound wave generated by the piezoelectric sheet 3.

[0060] 102: The piezoelectric element 3 is controlled by a signal generator to generate sound waves at the target frequency and maintain the target duration.

[0061] In this embodiment, the mapping relationship between focal length, frequency, and duration of action can be determined. When it is necessary to adjust the focal length of the concave lens array, the target focal length can be substituted into the mapping relationship to calculate the target frequency and duration of the sound wave generated by the piezoelectric element 3. Then, the piezoelectric element 3 is controlled by a signal generator to generate sound waves at the target frequency and maintain the target duration of action.

[0062] This application also provides a method for obtaining the above-mentioned mapping relationship. Specifically, obtaining the mapping relationship between focal length and frequency and action time includes the following steps:

[0063] 201: By using a signal generator, the piezoelectric element 3 is controlled to generate sound waves of different frequencies and for different durations, thereby obtaining the focal length of the bubble at different frequencies and durations.

[0064] 202: Using focal length as the dependent variable and frequency and duration of action as independent variables, curve fitting is performed to obtain the mapping relationship between focal length and frequency and duration of action.

[0065] Using pure water containing a suitable amount of the fluorescent dye Rhodamine B as a sample, after processing, the three-dimensional morphological features of the bubble lens array were revealed by Confocal scanning. Figure 3 As can be seen in the diagram, a is a three-dimensional scan of the overall bubble lens array, and i, ii, and iii in b are three-dimensional scan cross-sectional images of individual bubble lenses (i.e., concave lenses) of different sizes. It can be seen that the curvature changes significantly, indicating that a spherical lens has been made. iv in b is a three-dimensional scan of a single bubble lens (i.e., concave lens).

[0066] at the same time Figure 4 This demonstrates the process of using voice-controlled bubble size adjustment for focusing. The Cofocal longitudinal scan effect shows that... Figure 4 From a to b to c and then to d, the curvature of bubbles of different sizes changes significantly; similarly, the focal length also changes significantly. Figure 5 The study analyzed the effect of different sound wave frequencies on the bubble growth rate (i.e., sound wave focusing speed) at a sound wave intensity of 1.6W. The vertical axis represents the bubble diameter. It can be seen that the higher the frequency, the shorter the time required to reach the same bubble size, indicating that higher frequencies result in faster bubble growth. Finally, the imaging effect of the concave lens array is demonstrated. Figure 6 As shown, Figure 6 In the images, a and b represent the effects of imaging different slice images through a concave lens array, respectively. Image a shows a yin-yang symbol, while image b shows the letter F. Image c is a magnified representation of the imaging effect of a single bubble lens in image a. This demonstrates that this application can achieve adjustable focal length.

[0067] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0068] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0069] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An adjustable focal length concave lens array, characterized by, It comprises: The meta-microlens array generating module comprises a microfluidic chip (1) and a liquid inlet, the microfluidic chip (1) is provided with a microfluidic channel for forming a bubble lens array (2) of a gas dissolved in a liquid, and the microfluidic channel is communicated with the liquid inlet; The lens focal length adjusting module comprises a piezoelectric sheet (3) and a signal generator, the signal generator is connected with the piezoelectric sheet (3), and is used for inputting a frequency signal to the piezoelectric sheet (3), so that the piezoelectric sheet (3) generates an acoustic wave of a corresponding frequency according to the frequency signal, to control the bubble size of the bubble lens array (2) in the microfluidic channel; The piezoelectric sheet (3) is annular, the annular is a circular ring, and the meta-microlens array generating module is located in the middle of the piezoelectric sheet (3); The liquid inlet is connected with a micro flow pump, and the flow rate of the liquid entering the microfluidic channel from the liquid inlet is 1-2.5 μl / min; The microfluidic channel comprises a first layer cavity (4) and a second layer pit array (5), the second layer pit array (5) is located above the first layer cavity (4), the second layer pit array (5) comprises a plurality of pits for capturing bubbles, and the pits are communicated with the first layer cavity (4); The height of the first layer cavity (4) is 100 μm, the depth of the pit is 50 μm, the array specification of the second layer pit array (5) is 5×4 pit array, the radius of the pit is 50 μm, and the distance between the pits is 700 μm.

2. The focal length adjustable concave lens array of claim 1, wherein: The signal generator is connected with the piezoelectric sheet (3) through a power amplifier.

3. The focal length adjustable concave lens array of claim 1, wherein: The concave lens array further comprises a glass slide (6), and the meta-microlens array generating module and the piezoelectric sheet (3) are fixed on the glass slide (6).

4. The focal length adjustable concave lens array of claim 3, wherein: The meta-microlens array generating module and the piezoelectric sheet (3) are fixed on the glass slide (6) through an adhesive.

5. The focal length adjustable concave lens array of claim 4, wherein: The adhesive is a photocurable resin.

6. The focal length adjustable concave lens array of claim 5, wherein: The photocurable resin is an ultraviolet photocurable resin.

7. A method of adjusting the focal length of a concave lens array as claimed in any one of claims 1 to 6, characterized in that It comprises: According to the target focal length and the mapping relationship of focal length with respect to frequency and action time, the target frequency and the target action time of the acoustic wave generated by the piezoelectric sheet (3) are obtained; Through the signal generator, the piezoelectric sheet (3) generates an acoustic wave of the target frequency and lasts for the target action time.

8. The focal length adjustable concave lens array adjustment method according to claim 7, wherein, It further comprises the step of obtaining the mapping relationship of focal length with respect to frequency and action time, and obtaining the mapping relationship of focal length with respect to frequency and action time comprises: Through the signal generator, the piezoelectric sheet (3) generates acoustic waves of different frequencies and lasts for different action times, to obtain the focal length of the bubbles under different frequencies and different action times; With focal length as dependent variable, frequency and action time as independent variable, the mapping relationship of focal length about frequency and action time is obtained by curve fitting.

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