A method for realizing a high-resolution and fast-deflected light beam

Abstract

The present invention discloses a method for achieving a high-resolution and fast-deflecting light beam, including: realizing the deflected state of diffracted light through a light beam deflecting device; the light beam deflecting device includes a pre-stage acousto-optic deflector, a plurality of post-stage acousto-optic deflectors, and a driving device; the pre-stage acousto-optic deflector and each post-stage acousto-optic deflector are arranged in series; the driving device is used to generate and control the driving signals applied to the pre-stage and post-stage acousto-optic deflectors; realizing the deflected state of diffracted light includes: when the target sound field completely covers the light passing area of the target post-stage acousto-optic deflector, switching the driving signal of the pre-stage acousto-optic deflector to enable the laser beam to pass through the target post-stage acousto-optic deflector; when the laser beam passes through the target post-stage acousto-optic deflector and maintains a preset duration, immediately switching the driving signal of the pre-stage acousto-optic deflector to enable the laser beam to pass through the next target post-stage acousto-optic deflector or turn off the laser beam. The present invention can reduce the conversion time while improving the resolution during the light beam deflection process.

Description

Technical Field

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

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

[0003] Currently, common beam deflection methods can generally be divided into mechanical and non-mechanical methods. The former usually uses a high-speed galvanometer, a multi-faceted rotating mirror, or a microelectromechanical system (MEMS) scanning mirror to achieve beam deflection. However, due to the influence of mechanical inertia and processing accuracy, it is difficult to achieve very high speeds and high resolutions.

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

[0005] The main parameters of the AOD include:

[0006] (1) Diffraction efficiency η: It 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 ability: Usually measured by the number of resolvable points N of the AOD.

[0008] (3) Conversion time τ: It refers to the time required for the beam to deflect from one position to another position.

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

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

[0011] Therefore, during the beam deflection process, how to reduce the switching time while improving the resolution is an urgent problem to be solved by those skilled in the art. Summary of the Invention

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

[0013] To achieve the above object, the present invention adopts the following technical solutions:

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

[0015] The beam deflection device includes: a pre-stage acousto-optic deflector, a plurality of post-stage acousto-optic deflectors, and a driving device; wherein:

[0016] The pre-stage acousto-optic deflector and each of the post-stage acousto-optic deflectors are connected in series;

[0017] The driving device is used to generate and control the driving signals applied to the pre-stage acousto-optic deflector and the post-stage acousto-optic deflectors to realize the deflection or switching of the laser beam;

[0018] The realization of the deflection state of diffracted light through the beam deflection device specifically includes:

[0019] When the target sound field completely covers the light passing area of the target post-stage acousto-optic deflector, switch the driving signal of the pre-stage acousto-optic deflector to make the laser beam pass through the target post-stage acousto-optic deflector;

[0020] After the laser beam passes through the target post-stage acousto-optic deflector and maintains a preset duration, immediately switch the driving signal of the pre-stage acousto-optic deflector to make the laser beam pass through the next target post-stage acousto-optic deflector or turn off the laser beam.

[0021] Further, the conversion time of the pre-stage acousto-optic deflector is less than that of the post-stage acousto-optic deflector; and the resolution of the post-stage acousto-optic deflector is greater than that of the pre-stage acousto-optic deflector.

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

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

[0024] Further, the pre-stage acousto-optic deflector and the post-stage acousto-optic deflector are made of fused quartz crystal or tellurium dioxide crystal.

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

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

[0027] or, a combination of a single-channel acousto-optic deflector and a multi-channel acousto-optic deflector.

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

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

[0030] Control the driving device to apply a single-frequency or a mixed driving signal of multiple frequencies in the post-stage acousto-optic deflector or the acousto-optic deflection channel, so as to achieve the emission of a single diffracted light beam or multiple diffracted light beams.

[0031] Further, it further includes: achieving a non-diffraction state through a beam deflection device, specifically:

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

[0033] Through the above technical solutions, compared with the prior art, the present invention discloses a method for realizing high-resolution and fast beam deflection, which has the following beneficial effects:

[0034] The present invention overcomes the physical limitations suffered when only one acousto-optic deflector is used by connecting a pre-stage acousto-optic deflector and a post-stage acousto-optic deflector in series, where the pre-stage acousto-optic deflector has a small light passing aperture and the post-stage acousto-optic deflector has a large light passing aperture. During the beam deflection process, it is possible to reduce the conversion time while improving the resolution.

[0035] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0037] Figure 1 It is a schematic diagram showing the change of light intensity with time when the acousto-optic deflector provided by the embodiment of the present invention generates optical pulses.

[0038] Figure 2 It is a schematic diagram of the optical path setting corresponding to the beam deflection device provided by the embodiment of the present invention.

[0039] Figure 3 It is a schematic diagram of the fast switching and switching of the output light beam by the drive signal sequence provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

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

[0042] The above-mentioned beam deflection device includes: a pre-stage acousto-optic deflector, a plurality of post-stage acousto-optic deflectors, and a driving device; wherein: the pre-stage acousto-optic deflector and each post-stage acousto-optic deflector are connected in series; the driving device is used to generate and control the driving signals applied to the pre-stage acousto-optic deflector and the post-stage acousto-optic deflectors to realize the deflection or switching of the laser beam;

[0043] The above-mentioned realization of the deflected state of diffracted light through the beam deflection device specifically includes: when the target sound field completely covers the light passing area of the target post-stage acousto-optic deflector, switching the driving signal of the pre-stage acousto-optic deflector 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 a preset duration, immediately switch the driving signal of the pre-stage acousto-optic deflector 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 will be described in detail:

[0045] A schematic diagram of the variation of light intensity with time when an acousto-optic deflector (AOD) generates optical pulses can be seen in Figure 1 the figure shown. Since it takes time for the ultrasonic wave to cross the laser beam, the laser beam will have a rise time t1 and a fall time t2, where t1 = t2 = D / 2v. Further, this limits the width t3 of the optical pulse; it also limits the switching time t4 of the AOD (the fall time of the previous pulse + the rise time of the next pulse), as shown in Figure 1 the figure, where t4 = D / v.

[0046] In the embodiments of the present invention, the acousto-optic deflector (AOD) is divided into two stages, the front stage and the rear stage. The switching time of the front-stage acousto-optic deflector is less than that of the rear-stage acousto-optic deflector; and the resolution of the rear-stage acousto-optic deflector is greater than that 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 ability. Since the switching 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 as to achieve a rise time of less than 5 ns (corresponding to a switching frequency of more than 100 kHz). For example, for the front-stage acousto-optic deflector, fused silica crystal can be used. The sound velocity v of this crystal is approximately 6000 m / s. Combining with a light passing aperture D = 60 μm, its switching time is τ = D / v = 10 ns. The rear-stage acousto-optic deflector, on the other hand, selects a crystal with a slower sound velocity and designs a larger light passing aperture, so as to increase the resolvable points of the AOD to more than 500. For example, the rear-stage acousto-optic deflector can use a tellurium dioxide crystal with a beam diameter reaching 2 cm and a selected sound velocity v ≈ 4000 m / s, and its switching time is τ = D / v = 5 μs.

[0047] In the embodiments of the present invention, the front-stage acousto-optic deflector and the rear-stage acousto-optic deflector can use fused silica crystal or tellurium dioxide crystal.

[0048] For an ion trap quantum computer, the AOD is an important device for laser addressing. A high-resolution AOD means that the laser can manipulate more ion qubits and obtain a larger computing space. For example, for an AOD with 500 resolvable points, it can manipulate at most 500 ions, corresponding to a computing space of 2^500 dimensions, which means that it has a far greater acceleration ability for specific problems than classical computers. On the other hand, for a quantum computer to have practical application value, the calculation requires good fidelity. In laser operation, the decoherence of the phonon mode will affect the fidelity of the calculation. Short pulse widths and fast switching of the beam can quickly decouple the ions from the phonons, thereby reducing the influence of phonon mode decoherence and improving the fidelity of quantum computing.

[0049] In a laser direct writing system, the resolvable dot number of an AOD is the ratio of the laser direct writing area to the laser spot diameter. For example, for an AOD with a resolvable dot number of 500, a 1-mm direct writing area corresponds to a laser spot size of 2 μm, thus enabling fine lithography. On the other hand, the switching frequency of the AOD affects the speed of laser direct writing. For example, for a 100-kHz AOD with 500 steps, the switching time is only 5 ms, while for a 1-kHz AOD, it takes 500 ms. In comparison, the switching time required during the laser direct writing process can be significantly shortened, and with a higher-power laser source, the overall laser direct writing time can be greatly reduced.

[0050] A light-blocking device is provided directly behind the front acousto-optic deflector described above, which is used to block unwanted light beams to ensure that only the light beams that have undergone correct diffraction and guiding can be transmitted to the rear acousto-optic deflector.

[0051] A light-blocking device is also provided directly behind the rear acousto-optic deflector described above, which is used to ensure that the required light beams continue to be transmitted to the subsequent components.

[0052] A lens is provided directly in front of the rear acousto-optic deflector described above. Before the light beam enters the rear acousto-optic deflector, the beam waist size of the laser beam can be adjusted through the lens, so that the laser beam incident on the rear acousto-optic deflector has a larger diameter.

[0053] The multiple rear acousto-optic deflectors described above 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. The multiple rear acousto-optic deflectors or multiple channels of the rear acousto-optic deflector can be arranged in one dimension or two dimensions. However, they need to be arranged compactly to facilitate the overall optical path design and construction. When installing the front acousto-optic deflector with multiple rear acousto-optic deflectors, it should be noted that the diffracted light beams emitted by the front acousto-optic deflector need to be separated and enter different rear acousto-optic deflectors, and the placement angles of the rear acousto-optic deflectors need to meet the diffraction conditions.

[0054] Each rear acousto-optic deflector or each acousto-optic deflection channel has one diffracted light beam or multiple diffracted light beams; specifically: control the driving device to switch the driving signal applied to the front acousto-optic deflector to make the diffracted light pass through the rear acousto-optic deflector or the acousto-optic deflection channel; control the driving device to apply a single-frequency or a mixed driving signal of multiple frequencies in the rear acousto-optic deflector or the acousto-optic deflection channel, so as to achieve the emission of a single diffracted light beam or multiple diffracted light beams.

[0055] In summary, the beam deflection device provided by the embodiments of the present invention has two cascaded AODs in series, where the front-stage AOD has a fast conversion time and the rear-stage AOD has a high resolution. It overcomes the physical limitations when only one AOD is used, and can achieve an acousto-optic deflector with a conversion time of about 10 ns and a resolvable number of points reaching 500. The optical path of the present invention is set as shown in Figure 2 As shown, a laser source emits a beam with a small output beam waist diameter (for example, a laser with a wavelength of 600 nm and a beam waist diameter of 60 μm) into the acousto-optic deflection device. The beam waist of the beam is adjusted to the position of the front-stage acousto-optic deflector (i.e., the crystal 1 in Figure 2 ). At this time, the beam will undergo corresponding diffraction according to the driving signal applied to the crystal 1. Since the beam waist diameter of the beam passing through the crystal is very small, the diffracted light can be switched or deflected to the rear-stage acousto-optic deflector (i.e., the crystal 2 or crystal 3 in Figure 2 ) at a very high speed.

[0056] In order to combine the advantages of the front-stage AOD and the rear-stage AOD, the embodiments of the present invention adopt a method for achieving high-resolution and fast beam deflection, applying the above-mentioned beam deflection device, and realizing fast switching and toggling of the output beam of the device through a driving signal sequence. Specifically, it is used to achieve fast switching between different deflected states of diffracted light (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 the non-diffraction state. Among them:

[0057] (1) To achieve any deflected state of diffracted light, specifically including:

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

[0059] After the laser beam passes through the target rear-stage acousto-optic deflector and maintains a preset duration, immediately switch the driving signal of the front-stage acousto-optic deflector to make the laser beam pass through the next target rear-stage acousto-optic deflector.

[0060] (2) To achieve the non-diffraction state, specifically including:

[0061] Control the driving device not to apply a driving signal to the front-stage acousto-optic deflector to achieve the non-diffraction state.

[0062] For example, in Figure 3 , driving signals s2(t i ) and s3(t j ) are continuously output to the crystals 2 and 3 respectively. Among them, s2(t i ) represents the i-th segment of the target sound field propagating in the crystal 2, and s3(t j ) represents the j-th segment of the target sound field propagating in the 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 method for realizing a high-resolution fast-deflecting light beam provided by the present invention above, through timing control, the driving signals of the front and rear stages can be well coordinated, and the switching speed of the diffraction light frequency, amplitude, and phase can be greatly increased while ensuring the resolution ability remains unchanged.

[0069] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0070] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can 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 these embodiments shown herein, but rather will be accorded 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; 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.

2. 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.

3. 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.

4. A 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.

5. The 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.

6. A method for realizing high-resolution rapid deflection of a light beam according to claim 5, 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.

7. A 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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