Method for realizing high-resolution rapid beam deflection

Abstract

The invention discloses a method for realizing high-resolution rapid beam deflection. The method comprises the following steps: realizing a diffraction light deflection state through beam deflection equipment; the light beam deflection equipment comprises a front-stage acousto-optic deflector, a plurality of rear-stage acousto-optic deflectors and a driving device. The front-stage acousto-optic deflector and each rear-stage acousto-optic deflector are arranged in series; the driving device is used for generating and controlling driving signals applied to the front-stage acousto-optic deflector and the rear-stage acousto-optic deflector; the method for achieving the diffraction light deflection state comprises the steps that when a target sound field completely covers a light passing area of a target post-stage acousto-optic deflector, a driving signal of a pre-stage acousto-optic deflector is switched, and a laser beam is made to pass through the target post-stage acousto-optic deflector; and when the laser beam passes through the target post-stage acousto-optic deflector and is maintained for a preset duration, immediately switching the driving signal of the pre-stage acousto-optic deflector, so that the laser beam passes through the next target post-stage acousto-optic deflector or is closed. According to the invention, in the light beam deflection process, the resolution is improved, and the conversion time is shortened at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of light beam deflection, and more particularly to a method for realizing high-resolution rapid light beam deflection. Background Art

[0002] Beam deflection refers to the process of changing the direction of light beam propagation. It plays an important role in optics and photonics, and has a wide range of uses in biomedical imaging, material processing and manufacturing, display projection, communication sensing, and scientific research.

[0003] At present, common beam deflection methods can be generally divided into mechanical and non-mechanical methods. The former can usually use high-speed galvanometers, multi-faceted mirrors or micro-electromechanical system (MEMS) scanning mirrors to achieve beam deflection, but it is difficult to achieve high speed and high resolution due to the influence of mechanical inertia and processing accuracy.

[0004] Non-mechanical methods are usually implemented using an acousto-optic deflector (AOD). AOD is an optical device that uses the acousto-optic effect to control the propagation direction of a light beam. It first converts an externally applied RF drive signal into ultrasonic waves through a transducer, and then uses the ultrasonic waves to change the refractive index of the transparent medium, thereby causing the light beam passing through the medium to diffract or deflect. By rapidly modulating the RF drive signal, AOD can achieve high-speed, high-precision and flexible beam deflection control without mechanical movement.

[0005] The main parameters of AOD include:

[0006] (1) Diffraction efficiency η: refers to the ratio of the diffracted light power to the incident light power. It is related to the material properties of the acousto-optic crystal, the acoustic power, and the beam parameters.

[0007] (2) Resolution: usually measured by the number of resolvable points N of AOD.

[0008] (3) Conversion time τ: refers to the time required for a light beam to be deflected from one position to another.

[0009] (4) Bandwidth Δf: refers to the RF frequency range in which the AOD can work effectively. A larger bandwidth means a larger deflection angle range.

[0010] The AOD parameters listed above are not independent of each other, where the number of resolvable points N is approximately equal to the time-bandwidth product, that is, N≈τΔf. Therefore, when the bandwidth is fixed, the usual AOD cannot simultaneously improve the resolution and reduce the conversion time, and limits the performance of AOD in many applications. For example, in applications such as laser scanning microscopes and lidar, higher resolution and faster conversion time mean that higher resolution images can be obtained in both time and space. Similarly, for applications such as lithography machines and laser direct writing systems, higher resolution and faster conversion time mean that more sophisticated processing can be achieved. In scientific experiments, higher resolution and faster conversion time mean that optical tweezers can manipulate a larger number of atoms or molecules with higher temporal precision, which is of great significance for quantum computing.

[0011] Therefore, in the process of beam deflection, how to improve the resolution while reducing the conversion time is an urgent problem that technicians in this field need to solve. Summary of the invention

[0012] In view of the above problems, the present invention provides a method for realizing high-resolution rapid deflection of a light beam, so as to at least solve some of the technical problems mentioned in the above background technology.

[0013] In order to achieve the above object, the present invention adopts the following technical solution:

[0014] The present invention provides a method for realizing high-resolution rapid deflection of a light beam, comprising: realizing a diffracted light deflection state through a light beam deflection device;

[0015] The beam deflection device comprises: a front-stage acousto-optic deflector, a plurality of rear-stage acousto-optic deflectors and a driving device; wherein:

[0016] The front-stage acousto-optic deflector and each of the rear-stage acousto-optic deflectors are arranged in series;

[0017] The driving device is used to generate and control the driving signal applied to the front-stage acousto-optic deflector and the rear-stage acousto-optic deflector to realize the deflection or switching of the laser beam;

[0018] The step of realizing the diffracted light deflection state by using a beam deflection device specifically includes:

[0019] When the target sound field completely covers the light passing area of ​​the target rear-stage acousto-optic deflector, the driving signal of the front-stage acousto-optic deflector is switched to make the laser beam pass through the target rear-stage acousto-optic deflector;

[0020] When the laser beam passes through the target rear-stage acousto-optic deflector and maintains for a preset time, the driving signal of the front-stage acousto-optic deflector is immediately switched to make the laser beam pass through the next target rear-stage acousto-optic deflector or turn off the laser beam.

[0021] Furthermore, the switching time of the front-stage acousto-optic deflector is shorter than the switching time of the rear-stage acousto-optic deflector; and the resolution of the rear-stage acousto-optic deflector is greater than the resolution of the front-stage acousto-optic deflector.

[0022] Furthermore, a light blocking device is provided directly behind the front-stage acousto-optic deflector.

[0023] Furthermore, a lens is provided directly in front of the rear-stage acousto-optic deflector.

[0024] Furthermore, the front-stage acousto-optic deflector and the rear-stage acousto-optic deflector are made of fused quartz crystal or tellurium dioxide crystal.

[0025] Further, the plurality of post-stage acousto-optic deflectors are: at least two single-channel acousto-optic deflectors;

[0026] or, a multi-channel acousto-optic deflector of at least two channels;

[0027] Or, a combination of a single-channel AOD and a multi-channel AOD.

[0028] Furthermore, each subsequent acousto-optic deflector or each acousto-optic deflection channel has one or more diffracted light beams; specifically:

[0029] Controlling the driving device to switch the driving signal applied to the front-stage acousto-optic deflector so that the diffracted light passes through the rear-stage acousto-optic deflector or the acousto-optic deflection channel;

[0030] The driving device is controlled to apply a single-frequency or multi-frequency mixed driving signal in the subsequent acousto-optic deflector or acousto-optic deflection channel, thereby realizing the emission of a single beam of diffracted light or multiple beams of diffracted light.

[0031] Furthermore, it also includes: achieving a non-diffraction state by a beam deflection device, specifically:

[0032] The driving device does not apply a driving signal to the front-stage acousto-optic deflector to achieve a non-diffraction state.

[0033] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method for realizing high-resolution rapid deflection of light beams, which has the following beneficial effects:

[0034] The present invention connects two stages of acousto-optic deflectors in series, wherein the aperture of the front stage acousto-optic deflector is small and the aperture of the rear stage acousto-optic deflector is large. This overcomes the physical limitations of using only one acousto-optic deflector. In the process of light beam deflection, the resolution can be improved while the conversion time can be reduced.

[0035] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0037] Figure 1 A schematic diagram of the change of light intensity over time when an acousto-optic deflector generates a light pulse provided by an embodiment of the present invention.

[0038] Figure 2 A schematic diagram of the optical path setting corresponding to the light beam deflection device provided in an embodiment of the present invention.

[0039] Figure 3 A schematic diagram of the rapid switching of an outgoing light beam by a driving signal sequence provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The embodiment of the present invention discloses a method for realizing high-resolution rapid deflection of a light beam, comprising: realizing a diffracted light deflection state through a light beam deflection device;

[0042] The above-mentioned beam deflection device comprises: a front-stage acousto-optic deflector, a plurality of rear-stage acousto-optic deflectors and a driving device; wherein: the front-stage acousto-optic deflector and each rear-stage acousto-optic deflector are arranged in series; the driving device is used to generate and control the driving signal applied to the front-stage acousto-optic deflector and the rear-stage acousto-optic deflector to realize the deflection or switching of the laser beam;

[0043] The above-mentioned diffracted light deflection state is achieved by the beam deflection device, specifically including: when the target sound field completely covers the light-transmitting area of ​​the target post-stage acousto-optic deflector, the driving signal of the front-stage acousto-optic deflector is switched to make the laser beam pass through the target post-stage acousto-optic deflector; when the laser beam passes through the target post-stage acousto-optic deflector and maintains for a preset time, the driving signal of the front-stage acousto-optic deflector is immediately switched to make the laser beam pass through the next target post-stage acousto-optic deflector or turn off the laser beam.

[0044] Next, the above-mentioned beam deflection device is described in detail:

[0045] A schematic diagram of the variation of light intensity over time in the generation of light pulses by an acousto-optic deflector (AOD) can be found in Figure 1 As shown. Since it takes time for ultrasound to cross the laser beam, the laser beam will have a rise time t1 and a fall time t2, t1=t2=D / 2v. Further, this limits the width t3 of the light pulse; it also limits the AOD conversion time t4 (the fall time of the previous pulse + the rise time of the next pulse), as shown Figure 1 As shown, t4= D / v.

[0046] In the embodiment of the present invention, the acousto-optic deflector (AOD) is divided into two stages, front and rear, and the conversion time of the front-stage acousto-optic deflector is less than the conversion time of the rear-stage acousto-optic deflector; and the resolution of the rear-stage acousto-optic deflector is greater than the resolution of the front-stage acousto-optic deflector; specifically: the front-stage acousto-optic deflector is used to improve the switching speed, and the rear-stage acousto-optic deflector is used to ensure the resolution. Since the conversion time is τ=D / v, the front-stage acousto-optic deflector can select a crystal with a relatively fast sound velocity v, and reduce the beam diameter D of the crystal, so that a rise time of less than 5ns (corresponding to a switching frequency of more than 100kHz) can be achieved. For example, for the front-stage acousto-optic deflector, an acousto-optic crystal fused quartz crystal can be used, the sound velocity v of the crystal is ≈6000m / s, combined with the light aperture D=60um, and its conversion time is τ=D / v=10ns. The rear-stage acousto-optic deflector selects a crystal with a slower sound velocity and designs a larger light aperture, thereby increasing the number of resolvable points of the AOD to more than 500. For example, the post-stage acousto-optic deflector can use a beam diameter of 2 cm and select a tellurium dioxide crystal with a sound velocity v≈4000m / s, and its conversion time is τ=D / v=5us.

[0047] In the embodiment of the present invention, the front-stage acousto-optic deflector and the rear-stage acousto-optic deflector may be made of fused quartz crystal or tellurium dioxide crystal.

[0048] For ion trap quantum computers, AOD is an important device for laser addressing. High-resolution AOD means that the laser can manipulate more ion quantum bits and obtain a larger computing space. For example, for an AOD with 500 resolvable points, it can manipulate up to 500 ions, corresponding to a 2^500-dimensional computing space, which means that it has an acceleration capability far exceeding that of classical computers for specific problems. On the other hand, for quantum computers to have practical application value, calculations need to have good fidelity. In laser operations, the decoherence of phonon modes will affect the fidelity of calculations. Short pulse widths and rapid switching of light beams can quickly decouple ions and phonons, thereby reducing the impact of phonon mode decoherence and improving the fidelity of quantum computing.

[0049] In the laser direct writing system, the number of resolvable points of the AOD is the ratio of the laser direct writing area to the laser spot diameter. For example, for an AOD with a resolvable number of 500 points, a 1mm direct writing area corresponds to a 2um laser spot size, thereby achieving fine lithography. On the other hand, the switching frequency of the AOD will affect the speed of laser direct writing. For example, for a 100kHz AOD to step 500 times, the switching time only takes 5ms, while a 1kHz AOD takes 500ms. In comparison, the switching time required in the laser direct writing process can be greatly shortened, and the entire laser direct writing time can be greatly reduced with a higher power laser source.

[0050] A light blocking device is provided directly behind the front-stage acousto-optic deflector to block unnecessary light beams, ensuring that only light beams that have been correctly diffracted and guided can be transmitted to the rear-stage acousto-optic deflector.

[0051] A light blocking device is also provided directly to the rear of the above-mentioned rear-stage acousto-optic deflector to ensure that the required light beam continues to be transmitted to the subsequent components.

[0052] A lens is arranged directly in front of the above-mentioned rear-stage acousto-optic deflector. The waist size of the laser beam can be adjusted by the lens before the light beam enters the rear-stage acousto-optic deflector, so that the laser beam entering the rear-stage acousto-optic deflector has a larger diameter.

[0053] The above-mentioned multiple rear-stage acousto-optic deflectors are: at least two single-channel acousto-optic deflectors; or, a multi-channel acousto-optic deflector with at least two channels; or, a combination of a single-channel acousto-optic deflector and a multi-channel acousto-optic deflector. Multiple rear-stage acousto-optic deflectors or multiple channels of rear-stage acousto-optic deflectors can be arranged in one dimension or in two dimensions. However, they need to be arranged compactly to facilitate the overall optical path design and construction. When the front-stage acousto-optic deflector is installed with multiple rear-stage acousto-optic deflectors, it should be noted that the diffracted light beam emitted by the front-stage acousto-optic deflector needs to be able to be separated and shot into different rear-stage acousto-optic deflectors, and the placement angle of the rear-stage acousto-optic deflector needs to be able to meet the diffraction conditions.

[0054] Each subsequent acousto-optic deflector or each acousto-optic deflection channel has a beam of diffracted light or multiple beams of diffracted light; specifically: the driving device is controlled to switch the driving signal applied to the previous acousto-optic deflector, so that the diffracted light passes through the subsequent acousto-optic deflector or the acousto-optic deflection channel; the driving device is controlled to apply a single-frequency or a mixed-frequency driving signal in the subsequent acousto-optic deflector or the acousto-optic deflection channel, thereby realizing the emission of a single beam of diffracted light or multiple beams of diffracted light.

[0055] In summary, the beam deflection device provided by the embodiment of the present invention, by connecting two AODs in series, wherein the conversion time of the front AOD is fast and the resolution of the rear AOD is high. This overcomes the physical limitations of using only one AOD, and can achieve an acousto-optic deflector with a conversion time of about 10ns and a resolution of 500 points. The optical path of the present invention is set as follows Figure 2 As shown, the laser source outputs a beam with a smaller waist diameter (for example, a laser with a wavelength of 600nm and a waist diameter of 60um) into the acousto-optic deflection device. The beam waist is adjusted to the front stage acousto-optic deflector (i.e. Figure 2 The position of crystal 1 in the crystal 1 is determined by the diffraction of the light beam according to the driving signal applied to crystal 1. Since the waist diameter of the light beam passing through the crystal is very small, the diffracted light can be switched or deflected to the subsequent acousto-optic deflector (i.e. Figure 2 Crystal 2 or Crystal 3 in the image).

[0056] In order to combine the advantages of the front-stage AOD and the rear-stage AOD, the embodiment of the present invention uses a method for realizing high-resolution rapid deflection of the light beam, applies the above-mentioned beam deflection device, and realizes rapid switching and switching of the light beam of the device through a driving signal sequence. Specifically, it is used to realize rapid switching between different diffracted light deflection states (i.e., the diffracted light is deflected by the front-stage acousto-optic deflector and then incident on the rear-stage acousto-optic deflector) and non-diffraction states. Among them:

[0057] (1) Realize arbitrary diffraction light deflection state, including:

[0058] When the target sound field completely covers the light passing area of ​​the target rear-stage acousto-optic deflector, the driving signal of the front-stage acousto-optic deflector is switched to make the laser beam pass through the target rear-stage acousto-optic deflector;

[0059] When the laser beam passes through the target rear-stage acousto-optic deflector and maintains for a preset time, the driving signal of the front-stage acousto-optic deflector is immediately switched to make the laser beam pass through the next target rear-stage acousto-optic deflector.

[0060] (2) Achieving a diffraction-free state, specifically including:

[0061] The driving device is controlled not to apply a driving signal to the front-stage acousto-optic deflector to achieve a diffraction-free state.

[0062] For example, Figure 3 In the process, the driving signal s2 (t i ) and s3(t j ). Among them, s2(t i ) represents the i-th target sound field propagating in crystal 2, s3(t j ) represents the jth target sound field propagating in crystal 3. Figure 3The sound field in the crystal propagates to the right. When the n-1th sound field s2(t n-1 ) completely leaves the light-transmitting area of ​​crystal 2 (the square frame in the figure) and at the same time the nth segment of the sound field s2 (t n ) completely covers the light-transmitting area of ​​crystal 2, the driving signal of crystal 1 is switched to make the light beam pass through crystal 2. At this time, the diffracted light is affected by s2(t n ) The sound field is modulated. At the same time, the driving device outputs a signal to the crystal 3 to generate the next target sound field s3 (t m ).

[0063] In the m-1th sound field s3(t m-1 ) completely leaves the light-transmitting area of ​​crystal 3 (i.e., the mth segment of the sound field s3(t m ) completely covers the light-transmitting area of ​​crystal 3), and the diffracted light is affected by s2 (t n )When the modulation time of the sound field reaches the preset time, the driving signal of crystal 1 is immediately switched to make its laser beam incident on crystal 3, so that the diffracted light is diverted from the original light s2(t n ) The modulation of the sound field is quickly switched to s3(t m ) Modulation of the sound field. This conversion time can be as short as tens of nanoseconds, which is impossible for the high-resolution AOD itself to achieve.

[0064] At the same time, the driving device outputs a signal to crystal 2 to generate the next target sound field s2 (t n+1 ). Similarly, by applying the above steps, the diffracted light can be quickly switched to the next deflection state.

[0065] Specifically, the above-mentioned quantum computer and laser direct writing system are used as examples respectively.

[0066] During quantum computing, a 100ns light pulse can be applied in state 2 to address a one-dimensional ion lattice consisting of 500 ions. The irradiated ions gain momentum and become entangled with the phonons in the lattice. After this light pulse ends, it is immediately switched to state 3 and another 100ns light pulse is applied to disentangle these ions from the phonons, leaving only the entanglement between the ions, thus completing a fast quantum entanglement operation.

[0067] During the laser direct writing process, material A on the substrate surface can be exposed for 100ns in state 2. After the exposure is completed, it takes 10ns to switch to state 3 and continue to expose B, thereby shortening the time required for the overall lithography without affecting the lithography area and spot size.

[0068] Based on the above method of realizing high-resolution rapid deflection of light beams provided by the present invention, the driving signals of the front and rear stages can be well coordinated through timing control, which can greatly improve the switching speed of the diffracted light frequency, amplitude and phase while ensuring the resolution remains unchanged.

[0069] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0070] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for realizing high-resolution rapid deflection of a light beam, characterized in that: include: A diffracted light deflection state is achieved by a beam deflection device; The beam deflection device comprises: a front-stage acousto-optic deflector, a plurality of rear-stage acousto-optic deflectors and a driving device; wherein: The front-stage acousto-optic deflector and each of the rear-stage acousto-optic deflectors are arranged in series; The driving device is used to generate and control the driving signal applied to the front-stage acousto-optic deflector and the rear-stage acousto-optic deflector to realize the deflection or switching of the laser beam; The step of realizing the diffracted light deflection state by using a beam deflection device specifically includes: When the target sound field completely covers the light passing area of ​​the target rear-stage acousto-optic deflector, the driving signal of the front-stage acousto-optic deflector is switched to make the laser beam pass through the target rear-stage acousto-optic deflector; When the laser beam passes through the target rear-stage acousto-optic deflector and maintains for a preset time, the driving signal of the front-stage acousto-optic deflector is immediately switched to make the laser beam pass through the next target rear-stage acousto-optic deflector or turn off the laser beam.

2. A method for realizing high-resolution rapid deflection of a light beam according to claim 1, characterized in that: The switching time of the front-stage acousto-optic deflector is shorter than the switching time of the rear-stage acousto-optic deflector; and the resolution of the rear-stage acousto-optic deflector is greater than the resolution of the front-stage acousto-optic deflector.

3. A method for realizing high-resolution rapid deflection of a light beam according to claim 1, characterized in that: A light blocking device is provided directly behind the front-stage acousto-optic deflector.

4. A method for realizing high-resolution rapid deflection of a light beam according to claim 1, characterized in that: A lens is arranged directly in front of the rear-stage acousto-optic deflector.

5. The method for realizing high-resolution rapid deflection of a light beam according to claim 1, characterized in that: The front-stage acousto-optic deflector and the rear-stage acousto-optic deflector are made of fused quartz crystal or tellurium dioxide crystal.

6. A method for realizing high-resolution rapid deflection of a light beam according to claim 1, characterized in that: The multiple post-stage acousto-optic deflectors are: at least two single-channel acousto-optic deflectors; or, a multi-channel acousto-optic deflector of at least two channels; Or, a combination of a single-channel AOD and a multi-channel AOD.

7. A method for realizing high-resolution rapid deflection of a light beam according to claim 6, characterized in that: Each subsequent acousto-optic deflector or each acousto-optic deflection channel has one or more diffracted lights; specifically: Controlling the driving device to switch the driving signal applied to the front-stage acousto-optic deflector so that the diffracted light passes through the rear-stage acousto-optic deflector or the acousto-optic deflection channel; The driving device is controlled to apply a single-frequency or multi-frequency mixed driving signal in the subsequent acousto-optic deflector or acousto-optic deflection channel, thereby realizing the emission of a single beam of diffracted light or multiple beams of diffracted light.

8. The method for realizing high-resolution rapid deflection of a light beam according to claim 1, characterized in that: Also includes: The non-diffraction state is achieved by a beam deflection device, specifically: The driving device does not apply a driving signal to the front-stage acousto-optic deflector to achieve a non-diffraction state.

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