Spiral cone light beam dynamic regulation and control device and method based on spatial dislocation

Abstract

The invention relates to the technical field of light field regulation and control, and discloses a spiral cone light beam dynamic regulation and control device based on spatial dislocation, which comprises a light source, a quarter-wave plate and a light field regulation and control unit, and is characterized in that the light field regulation and control unit comprises a first phase modulation device, a second phase modulation device and a third phase modulation device which are sequentially arranged at intervals; the light source outputs linearly polarized laser; the quarter-wave plate is used for modulating the linear polarization laser into circular polarization laser; the first phase modulation device is used for carrying out first phase modulation on incident circular polarization laser, the first phase modulation device is shifted by a certain distance in the horizontal (or vertical) direction, the spot size of a generated spiral cone light beam is dynamically regulated and controlled, and a generated first modulation light beam is emitted to the second phase modulation device. The spatial dislocation is associated with the light spot size and the screw pitch size of the spiral cone light beam, so that single-parameter or double-parameter simultaneous dynamic regulation and control of the light spot size and the screw pitch size of the spiral cone light beam can be realized.

Description

Technical Field

[0001] This invention relates to the field of light field manipulation technology, and in particular to a device and method for dynamic manipulation of a spiral conical beam based on spatial misalignment. Background Technology

[0002] Optical field manipulation technology refers to a class of cutting-edge optical technologies that achieve precise design and manipulation of optical fields by actively controlling the spatial and temporal distribution of various physical properties of light waves (such as amplitude, phase, polarization, frequency, and wavefront shape). Its core objective is to break through the limitations of traditional optical devices, "customize" optical fields on demand, and provide entirely new solutions for modern optical applications. It features high spatial resolution, high diffraction efficiency, and wide-band compatibility, and can be used to generate and manipulate various beam structures, including phase-dominated beams, amplitude-phase co-controlled beams, and spatiotemporally coupled beams. It has wide applications in advanced imaging and microscopy, optical capture and manipulation, communication and information processing, and novel displays and holography.

[0003] A spiral conical beam is a special optical field with a unique intensity and phase distribution due to its spiral conical structure. This unique structure makes it a powerful and flexible tool for optical manipulation, a key carrier for high-capacity communication, a special probe for improving imaging resolution and detection sensitivity, and a unique light source for novel micro- and nano-fabrication and the study of fundamental physical phenomena. However, the current inability to generate spiral conical beams with specific spot sizes and pitches in a timely manner according to application needs limits its applications.

[0004] Existing patents also include some measurement devices and / or methods related to helical beam modulation, such as the Chinese invention patent with application number 202210969797.0, entitled "Multi-helical Phase Mask, Method for Generating Multi-helical Beams, and Optical Modulator." This patent combines a multi-helical phase mask with a multi-helical phase factor. By controlling and adjusting the parameters in this multi-helical phase factor, the number and orientation of the lobes in the multi-helical beam can be adjusted, realizing a multi-helical phase mask with freely adjustable lobes and direction. This enables the manipulation of particles by multiple helical beams, providing potential applications in the field of particle manipulation, especially suitable for cell transport and guidance. However, its main purpose is to address the problem that existing technologies can only manipulate particles with a single helical beam, resulting in a relatively limited mode. It cannot achieve real-time dynamic control of the spot size and pitch of the helical conical beam.

[0005] For example, Chinese invention patent application number 202011007447.3, entitled "Method for Preparing a Spiral Phase Modulation Sheet and a Method for Generating a Vortex Beam," utilizes ultraviolet exposure and subsequent heat treatment of photothermal refractive glass with high thermal stability and high laser damage threshold to form a spiral phase modulation sheet, thereby efficiently and rapidly generating a vortex beam. This preparation method is simple, and the resulting spiral phase modulation sheet has a large effective aperture, reaching hundreds of millimeters. The spiral phase modulation form can be flexibly changed by controlling the ultraviolet beam intensity distribution; the spiral phase modulation amplitude can be flexibly changed by controlling the ultraviolet beam irradiation flux. Its main purpose is to solve the problem of preparing large-aperture spiral phase modulation sheets, but it also cannot achieve real-time dynamic control of the spot size and pitch of the spiral conical beam. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention aims to provide a dynamic control device and method for a spiral conical beam based on spatial misalignment. By associating spatial misalignment with the spot size and pitch of the spiral conical beam, it is possible to achieve simultaneous dynamic control of the spot size and pitch of the spiral conical beam using a single parameter or two parameters.

[0007] This invention employs the following technical solution: a dynamic control device for a spiral conical beam based on spatial misalignment, comprising a light source, a quarter-wave plate, and a light field control unit. The light field control unit includes a first phase modulator, a second phase modulator, and a third phase modulator arranged sequentially at intervals. The light source outputs linearly polarized laser light. The quarter-wave plate modulates the linearly polarized laser light into circularly polarized laser light. The first phase modulator performs initial phase modulation on the incident circularly polarized laser light. By shifting the first phase modulator along a certain distance in the horizontal (or vertical) direction, the spot size of the final generated spiral conical beam is dynamically controlled. The generated first modulated beam is emitted to the second phase modulator; the second phase modulator is used to perform a second phase modulation on the incident first modulated beam. By offsetting the second phase modulator along a certain distance in the vertical (or horizontal) direction, the pitch of the final generated spiral cone beam is dynamically controlled, and the generated second modulated beam is emitted to the third phase modulator; the third phase modulator, whose phase is the fixed phase portion of the generated spiral cone beam, remains stationary during the control process, and is used to perform a third phase modulation on the incident second modulated beam to generate a spiral cone beam with dynamically controllable spot size and pitch.

[0008] A method for dynamic control of a spiral conical beam based on spatial misalignment, using the aforementioned spiral conical beam dynamic control device based on spatial misalignment, includes the following steps:

[0009] Step 1: Turn on the light source so that the output linearly polarized laser passes through a quarter-wave plate with the fast axis at a 45-degree angle to the horizontal direction, thereby modulating the incident linearly polarized laser into a circularly polarized direction and incident on the light field control unit.

[0010] Step 2: The circularly polarized laser sequentially passes through the first phase modulation device, the second phase modulation device, and the third phase modulation device in the optical field modulation unit, which are axially aligned and have no horizontal or vertical offset. After propagating for a certain distance, it generates a perfect vortex beam with a certain spot size and a pitch of 0.

[0011] Step 3: The first phase modulation device is offset by a certain distance along the horizontal (or vertical) direction. As the offset amount changes, the perfect vortex beam is transformed into a spiral cone beam, and the pitch of the spiral cone beam changes linearly with the offset amount, thereby realizing the dynamic control of the pitch of the spiral cone beam.

[0012] Step 4: The second phase modulation device is offset by a certain distance along the vertical (or horizontal) direction. As the offset amount changes, the spot size of the spiral cone beam changes linearly, thereby realizing the dynamic control of the spot size of the spiral cone beam.

[0013] Step 5: The first phase modulator and the second phase modulator are offset by a certain distance along the horizontal and vertical directions, respectively. As the offset amount changes, the spot size and pitch of the spiral cone beam change accordingly, so as to achieve dynamic control of the spot size and pitch of the spiral cone beam at the same time.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a dynamic control device and method for a spiral conical beam based on spatial misalignment, which, by associating spatial misalignment with the spot size and pitch of the spiral conical beam, can generate a spiral conical beam with a specific spot size and pitch as needed. The spiral conical beam has good dynamic control capability and can be used in scenarios such as particle manipulation experiments in optical tweezers systems. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the spiral cone beam dynamic control device based on spatial misalignment of the present invention;

[0016] Figure 2 This is a schematic diagram of the phase distribution of the first phase modulation device in this invention;

[0017] Figure 3 This is a schematic diagram of the phase distribution of the second phase modulation device in this invention;

[0018] Figure 4 This is a schematic diagram of the phase distribution of the third phase modulation device in this invention;

[0019] Figure 5 This is a schematic diagram of the simulation results when the first phase modulation device is individually controlled by the spiral cone beam dynamic control device based on spatial misalignment according to the present invention.

[0020] Figure 6 This is a schematic diagram of the simulation results when the spiral cone beam dynamic control device based on spatial misalignment of the present invention controls the second phase modulation device alone;

[0021] Figure 7 This is a schematic diagram of the simulation results when the spiral cone beam dynamic control device based on spatial misalignment of the present invention simultaneously controls the first phase modulation device and the second phase modulation device.

[0022] Figure 8 This is a schematic diagram illustrating the implementation process of the spiral cone beam dynamic control method based on spatial misalignment according to the present invention.

[0023] In the figure: 100 - optical field modulation unit; 110 - first phase modulation device; 120 - second phase modulation device; 130 - third phase modulation device; 200 - light source; 210 - quarter-wave plate. Detailed Implementation

[0024] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0025] The purpose of this invention is to address the shortcomings of existing technologies by providing a dynamic control device and method for a spiral conical beam based on spatial misalignment.

[0026] Example 1

[0027] This embodiment provides a dynamic control device for a spiral cone beam based on spatial misalignment, referring to... Figure 1As shown, it includes: a light source 200, a quarter-wave plate 210, and a light field modulation unit 100. The light field modulation unit 100 includes a first phase modulation device 110, a second phase modulation device 120, and a third phase modulation device 130 arranged opposite to each other. In this embodiment, the light source 200 can be a 532nm green solid-state laser, and the output laser is a linearly polarized laser with a center wavelength of 532nm and a spot size of 10mm. The quarter-wave plate 210 can be a 532nm air-gap quarter-wave plate, used to modulate the linearly polarized laser into a circularly polarized laser. The three phase modulation devices can be phase modulators made of liquid crystal polymer, with a phase delay of 266nm.

[0028] The spatial phase distributions of the first phase modulator 110, the second phase modulator 120, and the third phase modulator 130 under right-hand circularly polarized incident radiation are as follows:

[0029]

[0030]

[0031]

[0032] Where (x, y) are the spatial coordinates of the phase modulation device; k is the wavenumber of the incident laser, which in this embodiment can be 2π / 532 nm. -1 ; a is the modulation coefficient, used to control the degree of change of the pitch and spot size of the generated spiral cone beam with the position offset of the first phase modulator 110 and the second phase modulator 120. In this embodiment, 1 / 204 can be selected; r0 is the size coefficient, which is used to determine the initial spot size of the generated spiral cone beam. In this embodiment, 1 mm can be selected; d is the propagation distance required for the laser to evolve into a spiral cone beam after passing through the third phase modulator 130. In this embodiment, 500 mm can be selected; l is the topological charge, which describes the magnitude of the angular gradient of the phase of the spiral cone beam.

[0033] The single-wavelength linearly polarized laser output from the light source 200 is incident on a quarter-wave plate 210 whose fast axis forms a 45-degree angle with the horizontal direction, thereby modulating the laser polarization direction to a right-hand circular polarization direction and incident on the first phase modulation device 110.

[0034] The first phase modulation device 110 modulates the phase distribution of the right-hand circularly polarized laser as follows: Figure 2 As shown, after the incident right-hand circularly polarized laser passes through the first phase modulation device 110, it undergoes the first phase modulation and modulates its polarization direction to the left-hand circularly polarized direction, thereby generating a left-hand circularly polarized first modulated beam, which is then incident on the second phase modulation device 120.

[0035] The second phase modulation device 120 modulates the phase distribution of the left-hand circularly polarized laser as follows: Figure 3 As shown, the incident left-hand circularly polarized first modulated beam undergoes a second phase modulation after passing through the first phase modulator 120, and its polarization direction is modulated to a right-hand circularly polarized direction, thereby generating a right-hand circularly polarized second modulated beam, which is then incident on the third phase modulator 130.

[0036] The third phase modulator 130, whose phase is the fixed phase portion of the generated spiral conical beam, remains stationary during modulation. Its modulation phase distribution for the right-hand circularly polarized laser is as follows: Figure 4 As shown, the incident right-hand circularly polarized second modulated beam undergoes a third phase modulation after passing through the third phase modulator 130, and its polarization direction is modulated to a left-hand circularly polarized direction. Finally, after propagating dmm, a spiral conical beam with controllable spot size and pitch is generated.

[0037] Reference Figures 5-7 As shown, the white line below 1.25mm in Figure a is the window ruler of the image. The length and width of each image in Figure ai are 4 times the size of the ruler, i.e., 5mm.

[0038] Reference Figure 5 As shown, by shifting the first phase modulation device 110 a certain distance along the horizontal direction, the spot size of the generated spiral cone beam can be dynamically controlled. Figure 5 In the diagram, ai represents the light intensity distribution of the spiral cone beam when the second phase modulator 120 remains unchanged when offset by 1.02mm in the vertical direction, and when the first phase modulator 110 is offset by -1.02mm, -765μm, -510μm, -255μm, 0μm, 255μm, 510μm, 765μm, and 1.02mm in the horizontal direction, respectively. The positive and negative signs correspond to the offset direction (horizontal to the left or horizontal to the right).

[0039] Reference Figure 6 As shown, by shifting the second phase modulation device 120 a certain distance along the vertical direction, the pitch of the generated spiral cone beam can be dynamically adjusted. Figure 6 In the diagram, ai represents the light intensity distribution of the spiral cone beam when the first phase modulator 110 remains unchanged when offset by -1.02mm in the horizontal direction, and when the second phase modulator 120 is offset by -1.02mm, -765μm, -510μm, -255μm, 0μm, 255μm, 510μm, 765μm, and 1.02mm in the vertical direction, respectively. The positive and negative signs correspond to the offset direction (vertical upward or vertical downward).

[0040] Reference Figure 7As shown, by offsetting the first phase modulator 110 and the second phase modulator 120 by a certain distance along the horizontal and vertical directions respectively, the spot size and pitch of the generated spiral cone beam can be dynamically controlled simultaneously. Figure 7 In the figure, ai represents the light intensity distribution of the spiral cone beam when the offset of the first phase modulator 110 and the offset of the second phase modulator 120 are -1.02mm, -765μm, -510μm, -255μm, 0μm, 255μm, 510μm, 765μm, and 1.02mm, respectively, and the positive and negative signs correspond to the offset direction.

[0041] Example 2

[0042] This embodiment presents a method for dynamic control of a spiral cone beam based on spatial misalignment, referring to... Figure 8 As shown, it includes the following steps:

[0043] Step 1: Turn on the light source 200 so that the output linearly polarized laser passes through a quarter-wave plate 210 with its fast axis at a 45-degree angle to the horizontal direction, thereby modulating the incident linearly polarized laser into a right-hand circularly polarized direction, obtaining a right-hand circularly polarized laser, and incident it into the light field control unit 100.

[0044] Step 2: The right-hand circularly polarized laser sequentially passes through the first phase modulation device 110, the second phase modulation device 120, and the third phase modulation device 130 aligned axially in the optical field modulation unit 100, and after propagating by dmm, it generates a perfect vortex beam with a certain spot size and a pitch of 0.

[0045] Step 3: The first phase modulation device 110 is offset by a certain distance along the horizontal direction. It can be seen that as the offset changes, the perfect vortex beam is transformed into a spiral cone beam, and the pitch of the spiral cone beam changes linearly with the offset, thus realizing the dynamic control of the pitch of the spiral cone beam.

[0046] Step 4: The second phase modulation device 120 is offset by a certain distance along the vertical direction. It can be seen that as the offset amount changes, the spot size of the spiral cone beam changes linearly, thereby realizing the dynamic control of the spot size of the spiral cone beam.

[0047] Step 5: The first phase modulator 110 and the second phase modulator 120 are offset by a certain distance along the horizontal and vertical directions, respectively. It can be seen that as the offset amount changes, the spot size and pitch of the spiral cone beam change accordingly, so as to achieve dynamic control of the spot size and pitch of the spiral cone beam at the same time.

[0048] The first phase modulator 110, the second phase modulator 120, and the third phase modulator 130 are phase modulators with a phase retardation of half a wavelength, fabricated from three liquid crystal materials. These three phase modulators can introduce conjugate modulation phases for incident circularly polarized light and change the polarization direction of the output laser (when left-handed (or right-handed) circularly polarized light is incident, the output laser polarization direction is right-handed (or left-handed)). For right-handed circularly polarized incident laser light, as it passes through the first phase modulator 110, the second phase modulator 120, and the third phase modulator 130 sequentially, the corresponding polarization direction changes sequentially according to "left-handed circular polarization—right-handed circular polarization—left-handed circular polarization," and is successively superimposed with phase φ. 01 -φ 02 φ 03 At this point, when the offsets of the first phase modulator 110 and the second phase modulator 120 along the x and y directions are Δx and Δy respectively, the total modulation phase superimposed when the laser passes through the three modulators is:

[0049]

[0050] in,

[0051]

[0052] In the formula, φ1, φ2 and φ3 correspond to the annular lens phase, the conical lens phase and the spiral cone phase carrying the vortex phase, respectively.

[0053] The presence of φ1 provides the spiral phase and initial beam size for the final output spiral cone beam;

[0054] φ2 is linearly related to the offset Δx of the first phase modulation device 110, and is used to control the scaling of the spiral cone beam size. The change of Δx will cause a change in the size of φ2, thereby enabling the adjustment of the output spiral cone beam size.

[0055] φ3 is linearly related to the offset Δy of the second phase modulator 120, and is used to generate the spiral conical beam structure and control the pitch of the spiral conical beam. Changes in Δy will cause changes in the size of φ3, thereby enabling adjustment of the pitch of the output spiral conical beam. When Δy is 0, the pitch of the spiral conical beam becomes 0, and the structure of the spiral conical beam is not present; the generated beam is a perfect vortex beam. When Δx and Δy change simultaneously, the sizes of φ2 and φ3 change simultaneously, thereby enabling simultaneous adjustment of the size and pitch of the output spiral conical beam.

[0056] This invention discloses a dynamic control device and method for a spiral conical beam based on spatial misalignment. The offsets of the first phase modulator 110 and the second phase modulator 120 correspond to the controlled parameters, including the beam size and pitch, enabling real-time dynamic control of the beam size and pitch. Due to constraints such as device specifications and laser beam size, the offsets of the first and second phase modulators have a certain control range; exceeding this range may result in beam distortion.

[0057] The present invention provides a spiral conical beam dynamic control device and method based on spatial misalignment, which can generate a spiral conical beam with a specific spot size and pitch as needed in a timely manner. The spiral conical beam has good dynamic control capability.

[0058] In some implementations, the aforementioned spiral cone beam can be introduced into an optical tweezers system to conduct particle manipulation experiments, enabling dynamic trajectory control of particles.

[0059] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A dynamic control device for a spiral conical beam based on spatial misalignment, characterized in that, include: The light source (200), quarter-wave plate (210), and light field modulation unit (100) are provided. The light field modulation unit (100) includes a first phase modulation device (110), a second phase modulation device (120), and a third phase modulation device (130) arranged sequentially at intervals. The light source (200) outputs linearly polarized laser; The quarter-wave plate (210) is used to modulate linearly polarized laser light into circularly polarized laser light. The first phase modulation device (110) is used to perform the first phase modulation on the incident circularly polarized laser. By shifting the first phase modulation device (110) a certain distance along the horizontal (or vertical) direction, the spot size of the final generated spiral cone beam is dynamically controlled, and the generated first modulated beam is emitted to the second phase modulation device (120). The second phase modulator (120) is used to perform a second phase modulation on the incident first modulated beam. By shifting the second phase modulator (120) a certain distance along the vertical (or horizontal) direction, the pitch of the final generated spiral cone beam is dynamically controlled, and the generated second modulated beam is emitted to the third phase modulator (130). The third phase modulation device (130) has a fixed phase portion of the generated spiral conical beam and remains stationary during the modulation process. It is used to perform a third phase modulation on the incident second modulation beam to generate a spiral conical beam with dynamically controllable spot size and pitch.

2. The spiral cone beam dynamic control device based on spatial misalignment according to claim 1, characterized in that: The light source (200) is a linearly polarized continuous light source.

3. The spiral cone beam dynamic control device based on spatial misalignment according to claim 2, characterized in that: The fast axis of the quarter-wave plate (210) forms a 45-degree angle with the horizontal direction.

4. The spiral cone beam dynamic control device based on spatial misalignment according to claim 3, characterized in that: The first phase modulator (110), the second phase modulator (120), and the third phase modulator (130) can introduce conjugate modulation phases for incident circularly polarized light of different polarizations. When right-handed circularly polarized light is incident, the spatial phase distributions of the three phase modulators are as follows: Where (x, y) are the spatial coordinates of the phase modulation device; k is the wave number of the incident laser; a is the modulation coefficient, which is used to control the pitch and spot size of the generated spiral cone beam as a function of the position offset of the first phase modulator (110) and the second phase modulator (120). r0 is the size factor, which is used to determine the initial spot size of the generated spiral cone beam; d is the propagation distance required for the laser to evolve into a spiral cone beam after passing through the third phase modulation device (130); l is the topological charge, describing the magnitude of the angular gradient of the phase of the spiral cone beam.

5. A method for dynamic control of a spiral conical beam based on spatial misalignment, using the spiral conical beam dynamic control device based on spatial misalignment as described in any one of claims 1-4, comprising the following steps: Step 1: Turn on the light source (200) so that the output linearly polarized laser passes through a quarter-wave plate (210) with the fast axis at a 45-degree angle to the horizontal direction, thereby modulating the incident linearly polarized laser into a circularly polarized direction and incident on the light field control unit (100). Step 2: The circularly polarized laser sequentially passes through the first phase modulator (110), the second phase modulator (120), and the third phase modulator (130) in the optical field control unit (100), which are axially aligned and have no horizontal or vertical offset. After propagating for a certain distance, it generates a perfect vortex beam with a certain spot size and a pitch of 0. Step 3: The first phase modulation device (110) is offset by a certain distance along the horizontal (or vertical) direction. As the offset amount changes, the perfect vortex beam is transformed into a spiral cone beam, and the pitch of the spiral cone beam changes linearly with the offset amount, thereby realizing the dynamic control of the pitch of the spiral cone beam. Step 4: The second phase modulation device (120) is offset by a certain distance along the vertical (or horizontal) direction. As the offset amount changes, the spot size of the spiral cone beam changes linearly, thereby realizing the dynamic control of the spot size of the spiral cone beam. Step 5: The first phase modulation device (110) and the second phase modulation device (120) are offset by a certain distance along the horizontal and vertical directions, respectively. As the offset amount changes, the spot size and pitch of the spiral cone beam change accordingly, so as to realize the dynamic control of the spot size and pitch of the spiral cone beam at the same time.

6. The method for dynamic control of a spiral cone beam based on spatial misalignment according to claim 5, characterized in that: The first phase modulator (110), the second phase modulator (120), and the third phase modulator (130) are phase modulators with a phase delay of half a wavelength.

7. The method for dynamic control of a spiral cone beam based on spatial misalignment according to claim 6, characterized in that: For a right-hand circularly polarized incident laser, as it passes through three phase modulation devices in sequence, the corresponding polarization direction changes sequentially according to "left-hand circular polarization—right-hand circular polarization—left-hand circular polarization," and is successively superimposed with phase φ. 01 -φ 02 φ 03 ; At this point, when the offsets of the first phase modulator (110) and the second phase modulator (120) along the x and y directions are Δx and Δy respectively, the total modulation phase superimposed when the laser passes through the three modulators is: in, In the formula, φ1, φ2 and φ3 correspond to the annular lens phase, the conical lens phase and the spiral cone phase carrying the vortex phase, respectively.

8. The method for dynamic control of a spiral cone beam based on spatial misalignment according to claim 7, characterized in that: The offsets of the first phase modulation device (110) and the second phase modulation device (120) in the x and y directions are related to the spot size and pitch, which can realize real-time dynamic control of the spot size and pitch.

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