Liquid Fresnel lens and ripple modulation method thereof

Abstract

The present invention relates to the field of optical lens technology, and in particular to a liquid Fresnel lens and a ripple modulation method thereof, comprising a transparent bottom surface, an optical liquid and an oscillation generator, wherein the upper surface of the transparent bottom surface has an optical liquid, and the oscillation generator is arranged in a ring structure at the outer edge of the upper surface of the transparent bottom surface; the oscillation generator modulates the optical liquid into an annular surface through a ripple modulation system connected thereto; the ripple modulation system comprises an upper computer, a lower computer and an analog modulation circuit, and the upper computer is used to decompose the Fresnel lens surface into a group of simple harmonic waves through Fourier transformation and send the phase, frequency and amplitude parameters of the simple harmonic waves to the lower computer in digital form. The present invention achieves the effect of "free focusing" of the optical liquid lens by modulating the oscillation waveform to change the light refraction path of the liquid wave surface, thereby realizing an optical lens with low cost, large optical aperture and electrically controllable focusing.

Description

Technical Field

[0001] The invention relates to the technical field of optical lenses, and in particular to a liquid Fresnel lens and a ripple modulation method thereof. Background Art

[0002] Fresnel lens is also called spiral lens. One side of the lens surface is smooth, and the other side is engraved with concentric circles from small to large. Its design idea is to assume that the refraction of a lens only occurs on the optical surface, and to minimize the use of optical materials while retaining the curvature of the lens surface. The curved surface of a typical Fresnel lens can be regarded as a continuous curved surface, which retains the curvature of different segments but is discontinuous. Compared with traditional lenses, Fresnel lenses can be made very thin, which is suitable for meeting the needs of large aperture lenses and high curvature lenses.

[0003] Traditional optical lenses rely on the optical curved surface produced during material processing to change the direction of light propagation and the focus of the original light beam. Once the lens is processed and finalized, the optical curved surface and focus cannot be changed, and the focus cannot be modulated during operation. Liquid lens is a technology that can solve the modulation problem of optical lens operation. Existing liquid lenses mainly rely on changing the curvature of the droplets sandwiched between the upper and lower films to achieve optical focus modulation (such as CN111812801A, CN111812801A). Affected by the surface tension and gravity of the liquid, it is difficult to increase the optical aperture.

[0004] Based on the above reasons, the present invention proposes a liquid Fresnel lens and a ripple modulation method thereof. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a liquid Fresnel lens and a ripple modulation method thereof, thereby realizing an optical lens with low cost, large optical aperture and electrically controllable focusing.

[0006] In order to achieve the purpose of the present invention, the technical solution adopted by the present invention is:

[0007] The present invention discloses a liquid Fresnel lens, comprising a transparent bottom surface, an optical liquid and an oscillation generator, wherein the upper surface of the transparent bottom surface has the optical liquid, and the oscillation generator is arranged in a ring structure at the outer edge of the upper surface of the transparent bottom surface; the oscillation generator modulates the optical liquid into an annular curved surface through a ripple modulation system connected thereto;

[0008] The ripple modulation system includes an upper computer, a lower computer and an analog modulation circuit. The upper computer is used to decompose the Fresnel lens surface into a group of simple harmonic waves through Fourier transform and send the phase, frequency and amplitude parameters of the simple harmonic waves to the lower computer in digital form; the lower computer is an MCU, and the MCU includes an excitation clock control, a digital pulse width control and a voltage amplification control for phase modulation. The digital pulse width control sends a digital pulse width modulation signal through the pin of the MCU for frequency modulation, and the voltage amplification control performs amplitude modulation through the amplitude modulation circuit. The MCU inputs the synthesized beam signal into the oscillation generator.

[0009] The amplitude modulation circuit includes a DA converter, a first fixed resistor, a transistor, an adjustable resistor and a second fixed resistor which are connected in sequence. The DA converter is connected to the digital pulse width control, and the second fixed resistor is connected to an oscillator generator.

[0010] A liquid Fresnel lens ripple modulation method comprises the following steps:

[0011] Step S1, in a host computer, decomposing a set two-dimensional Fresnel lens function surface into a set of simple harmonic wave functions by Fourier transform;

[0012] Step S2, sending the frequency, amplitude, phase and other parameters to the lower computer;

[0013] Step S3, respectively corresponding to phase modulation, frequency modulation and amplitude modulation of the excitation wave through excitation clock control, PWM and voltage amplification control;

[0014] Step S4, each decomposed wave function is output by a separate lower computer channel, and after digital-to-analog conversion and amplification, it is summed and output to the oscillation generator; the oscillation generator works to excite the ripples generated on the surface of the optical liquid to reconstruct into a liquid Fresnel lens.

[0015] The beneficial effects of the present invention are:

[0016] (1) The liquid Fresnel lens of the present invention is thin and suitable for manufacturing large-aperture lenses. It also has the property of real-time adjustment compared to traditional Fresnel lenses.

[0017] (2) The present invention achieves the effect of "free focusing" of optical liquid by modulating the oscillation waveform to change the light refraction path of the liquid wave surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of a liquid Fresnel lens in the present invention;

[0019] Figure 2 A schematic diagram of decomposing a two-dimensional Fresnel lens surface into several simple harmonic waves by Fourier transform in the present invention;

[0020] Figure 3 is a schematic diagram of the ripple modulation method of the present invention;

[0021] Figure 4 It is a schematic diagram of analog signal modulation of each channel in the present invention;

[0022] Figure 5 It is a schematic diagram of the amplitude modulation circuit in the present invention.

[0023] In the figure: 1 transparent bottom surface, 2 optical liquid, 3 oscillation generator, 4 ripple modulation system, 5 host computer, 6 MCU, 61 excitation clock control, 62 digital pulse width control, 63 voltage amplification control, 7 amplitude modulation circuit, 71 DA converter, 72 first fixed resistor, 73 transistor, 74 adjustable resistor, 75 second fixed resistor. DETAILED DESCRIPTION

[0024] The present invention is further described below:

[0025] See also Figure 1-5 ,

[0026] The present invention discloses a liquid Fresnel lens, comprising a transparent bottom surface 1, an optical liquid 2 and an oscillation generator 3, wherein the upper surface of the transparent bottom surface 1 has the optical liquid 2, and the oscillation generator 3 is arranged at the outer edge of the upper surface of the transparent bottom surface 2 in an annular structure; the oscillation generator 3 modulates the optical liquid 2 into an annular curved surface through a ripple modulation system 4 connected thereto; the ripple modulation system 4 comprises an upper computer 5, a lower computer and an analog modulation circuit, the upper computer 5 is used for decomposing the Fresnel lens curved surface into a group of simple harmonic waves through Fourier transform and sending the phase, frequency and amplitude parameters of the simple harmonic waves to the lower computer in digital form; the lower computer is an MCU 6, and the MCU comprises an excitation clock control 61 for phase modulation, a digital pulse width control 62 and a voltage amplification control 63, the digital pulse width control 62 sends a digital pulse width modulation signal through a pin of the MCU 6 for frequency modulation, and the voltage amplification control 63 performs amplitude modulation through an amplitude modulation circuit 7, The MCU6 inputs the synthesized beam signal to the oscillation generator 3; the lens is mainly composed of a transparent bottom surface 1, a shallow optical liquid 2 and an oscillation generator 3. The shallow optical liquid 2 in the device is excited by the oscillation generator 3 to generate water surface waves, and the liquid wave surface is synthesized into a ring-shaped surface similar to the Fresnel lens by modulating a specific oscillation frequency and amplitude; by modulating the oscillation waveform, the light refraction path of the liquid wave surface is changed, so as to achieve the effect of "free focusing" of the optical liquid; a low-cost, large optical aperture, electrically controllable focusing optical lens is realized; MCU6 is a micro control unit, also known as a single-chip microcomputer or a single-chip microcomputer, which appropriately reduces the frequency and specifications of the central processing unit, and integrates peripheral interfaces such as memory, counter, USB, A / D conversion, UART, PLC, DMA, and even LCD drive circuits on a single chip to form a chip-level computer, and perform different combination controls for different application scenarios; digital pulse width control 62 is PWM.

[0027] The amplitude modulation circuit 7 includes a DA converter 71, a first fixed resistor 72, a transistor 73, an adjustable resistor 74 and a second fixed resistor 75 connected in sequence. The DA converter 71 is connected to the digital pulse width control 62, and the second fixed resistor 75 is connected to the oscillator generator 3. The required function ripple signal is Fourier transformed through MCU5 and enters the amplitude modulation circuit 7 after passing through PWM6. The amplitude modulation circuit 7 includes a DA converter 71 for converting digital signals into analog signals, a first fixed resistor 72, a second fixed resistor 75, a transistor 73 and an adjustable resistor 74. Finally, the divided signals are summarized and input into the oscillator generator 3.

[0028] The present invention discloses a liquid Fresnel lens ripple modulation method, comprising the following steps:

[0029] Step S1, in the host computer 5, decomposing the set two-dimensional Fresnel lens function surface into a set of simple harmonic wave functions through Fourier transform;

[0030] Step S2, sending the frequency, amplitude, phase and other parameters to the lower computer;

[0031] Step S3, phase modulation, frequency modulation and amplitude modulation of the excitation wave are respectively controlled by the excitation clock control 61, the digital pulse width control 62 and the voltage amplification control 63;

[0032] Step S4, each decomposed wave function is output by a separate lower computer channel, and after digital-to-analog conversion and amplification, it is summed and output to the oscillation generator; the oscillation generator works to excite the ripples generated on the surface of the optical liquid to reconstruct into a liquid Fresnel lens.

[0033] Modulation process: Figure 3 As shown, the designed two-dimensional Fresnel lens surface is decomposed into a set of simple harmonic wave functions (such as Figure 2 As shown in the figure, the frequency, amplitude, phase and other parameters are sent to the lower computer. Clock control, digital pulse width (PWM) control and voltage amplification control correspond to the phase modulation, frequency modulation and amplitude modulation of the excitation wave respectively. Each decomposed wave function is output by a separate lower computer channel, and after digital-to-analog conversion and amplification, it is summed and output to the oscillator generator 3 (as shown in the figure). Figure 4 The oscillation generator 3 works to excite the ripples generated on the surface of the optical liquid to reconstruct into a liquid Fresnel lens.

[0034] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings or directly or indirectly applied in related technical fields are also included in the patent protection scope of the present invention.

Claims

1. A method for ripple modulation of a liquid Fresnel lens, comprising a liquid Fresnel lens, the liquid Fresnel lens comprising a transparent bottom surface (1), an optical liquid (2) and an oscillation generator (3), the upper surface of the transparent bottom surface (1) having the optical liquid (2), the oscillation generator (3) being arranged in a ring structure at the outer edge of the upper surface of the transparent bottom surface; the oscillation generator (3) modulates the optical liquid (2) into an annular curved surface through a ripple modulation system (4) connected thereto; the ripple modulation system (4) comprising an upper computer (5), a lower computer and an analog modulation circuit, the upper computer (5) being used for decomposing the curved surface of the Fresnel lens into a group of simple harmonic waves through Fourier transform and sending the phase, frequency and amplitude parameters of the simple harmonic waves to the lower computer in digital form; the lower computer is an MCU (6), The MCU comprises an excitation clock control (61) for phase modulation, a digital pulse width control (62) and a voltage amplification control (63); the digital pulse width control (62) performs frequency modulation by sending a digital pulse width modulation signal through a pin of the MCU (6); the voltage amplification control (63) performs amplitude modulation through an amplitude modulation circuit (7); the MCU (6) inputs the synthesized beam signal into the oscillator (3); the amplitude modulation circuit (7) comprises a DA converter (71), a first fixed resistor (72), a triode (73), an adjustable resistor (74) and a second fixed resistor (75) connected in sequence; the DA converter (71) is connected to the digital pulse width control (62); the second fixed resistor (75) is connected to the oscillator (3); and the characteristics are: The following steps are included: Step S1, in a host computer, decomposing a set two-dimensional Fresnel lens function surface into a set of simple harmonic wave functions by Fourier transform; Step S2, sending the frequency, amplitude, phase and other parameters to the lower computer; Step S3, respectively corresponding to phase modulation, frequency modulation and amplitude modulation of the excitation wave through excitation clock control, digital pulse width control and voltage amplification control; Step S4, each decomposed wave function is output by a separate lower computer channel, and after digital-to-analog conversion and amplification, it is summed and output to the oscillation generator; the oscillation generator works to excite the ripples generated on the surface of the optical liquid to reconstruct into a liquid Fresnel lens.

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