High-throughput laser direct writing device and method

Abstract

The invention relates to a high-flux laser direct writing device and a high-flux laser direct writing method. The device mainly comprises two core elements, namely a digital micromirror array DMD and an acousto-optic deflector AOD. The light source forms a linear light beam after being modulated, the linear light beam is controlled by the AOD to perform one-dimensional scanning, the scanning direction is orthogonal to the linear direction, and the scanning surface covers the surface of the DMD. The linear light beam modulated by the DMD is conjugated to the focal plane of the objective lens through a 4F system formed by the lens and the objective lens, two-dimensional graph processing can be completed through single scanning, and the laser direct writing processing efficiency can be greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano optics technology and optical component manufacturing, and particularly relates to a high-throughput laser direct writing device and method. Background Technology

[0002] Laser direct writing technology has advantages such as small thermal effects, no mask required, low environmental requirements and three-dimensional processing. Since its first proposal, it has attracted great attention and has always been a research hotspot in the field of micro-nano processing. It is not only one of the core technologies for high-end chip manufacturing, but also an indispensable research cornerstone for many cutting-edge scientific fields such as biomedicine, optical communication, optical storage, information science, microfluidics, and measurement and sensing.

[0003] Processing speed is an important indicator in laser direct writing technology. Traditional single-point scanning technology is very mature, but its processing efficiency is low and it is difficult to meet the growing processing needs.

[0004] Increasing the number of system channels can significantly improve the processing efficiency of laser direct writing. However, under high parallelism conditions, the independent control capability of each channel is difficult to guarantee, and the system complexity and operation difficulty increase significantly. Usually, only large-area repetitive structures can be processed.

[0005] Furthermore, in multi-channel parallel systems, it is difficult to maintain consistent spot quality and intensity distribution, further limiting the improvement of writing accuracy. This constitutes the "impossible triangle" in laser direct writing technology, namely, it is difficult to simultaneously achieve high throughput, accuracy, and flexibility. For example, the invention patents with publication numbers CN118466124A and CN114326322A, which are high-throughput super-resolution laser direct writing systems based on microlens arrays and DMDs, increase the laser direct writing throughput to four times, but the improvement in writing speed is limited. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a high-throughput laser direct writing device and method. This device, based on a digital micromirror array (DMD) and an acousto-optic deflector (AOD), enables high-throughput and high-precision processing of arbitrary graphics. In this invention, the light source is modulated to form a linear beam. The AOD controls the linear beam to perform a one-dimensional scan, with the scanning direction orthogonal to the linear direction, and the scanning surface covering the DMD surface. The linear beam modulated by the DMD is conjugated to the focal plane of the objective lens by a 4F system formed by the lens and objective lens. A single scan can complete the processing of a two-dimensional graphic, significantly improving the efficiency of laser direct writing.

[0007] The technical solution adopted in this invention is as follows: This invention provides a high-throughput laser direct writing device, comprising a laser arranged sequentially along the optical path, a shaping module for shaping the laser beam into a linear beam, an acousto-optic deflector for controlling the deflection angle of the linear beam, a beam expanding module for covering the scanning surface of the linear beam onto the surface of a digital micromirror array, the digital micromirror array for pattern modulation of the linear beam, and a processing module for imaging the modulated linear beam onto a focal plane for direct writing.

[0008] Preferably, the shaping module includes a Powell prism for shaping the laser emitted by the laser into linear light.

[0009] Furthermore, the shaping module also includes at least one cylindrical lens for collimating the linear light emitted from the Powell prism (which introduces a divergence angle) to form a collimated beam with a linear cross-section.

[0010] The linear light obtained by shaping is deflected by AOD, and the scanning surface is covered by the beam expansion module to make the scanning surface cover the DMD surface. Then, a one-dimensional scan is performed on the DMD surface.

[0011] The digital micromirror array includes multiple (hundreds of thousands) independently controllable sub-micromirrors, which are used as dynamic masks to generate arbitrary inscription patterns and modulate the scanned linear light.

[0012] Preferably, the processing module includes a lens and an objective lens arranged sequentially, forming a 4F system for conjugate imaging of the linear beam modulated by the digital micromirror array onto the focal plane of the objective lens. The processing module also includes a writing platform disposed behind the objective lens. Laser writing is performed on the writing platform.

[0013] In some embodiments of the present invention, when the laser is a femtosecond laser, the high-throughput laser direct writing device further includes a dispersion compensation element for compensating for the dispersion caused by the acousto-optic deflector, which is disposed in the input and output optical paths of the acousto-optic deflector.

[0014] Furthermore, the dispersion compensation element includes a triangular prism and a lens group; The triangular prisms are sequentially positioned in front of the acousto-optic deflector, and the linear light passes through the triangular prisms and the reflector in sequence before being collimated into the acousto-optic deflector.

[0015] The dispersion compensation element also includes a reflector for changing the direction of the light path. The reflector is located between the triangular prism and the acousto-optic deflector, so that the outgoing light path through the triangular prism can be collimated into the acousto-optic deflector.

[0016] The present invention also provides a high-throughput laser direct writing method, based on the above-described apparatus, comprising the following steps: S1. Shape the laser light generated by the laser into linear light; S2. Control the linear light to be deflected by the acousto-optic deflector, and then pass through the beam expander module so that the scanning surface covers the target surface of the digital micromirror array; S3. Using the independently controllable sub-micromirrors on the digital micromirror array, the linear light scanned to its target surface is dynamically patterned. S4. The modulated linear light is conjugated to its focal plane through the processing module, and laser direct writing is performed in the processing area located on the focal plane.

[0017] The beneficial effects of the present invention are: the laser direct writing device and method of the present invention combine two high-throughput optical modulation devices, an acousto-optic deflector and a digital micromirror array, and use the shaped linear light for scanning. A single one-dimensional scan can complete the two-dimensional writing of any pattern, which greatly improves the efficiency of laser direct writing processing while ensuring the system's writing flexibility and accuracy. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the yz and xz plane optical paths of the structure of this invention.

[0020] The diagram is labeled as follows: 1-Laser, 2-Powell prism, 3-Cylindrical lens, 4-Triangular prism, 5-Mirror, 6-Acousto-optic deflector, 7-Lens group, 8-Beam expander module, 9-Digital micromirror array, 10-Lens, 11-Objective lens, 12-Writing platform. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that, unless otherwise specified, the features in the following embodiments and implementation methods can be combined with each other.

[0023] Depend on Figure 1As shown, the present invention provides a high-throughput laser direct writing device, comprising a laser 1 arranged sequentially along the optical path, a shaping module for shaping the beam into linear light, an acousto-optic deflector 6 for controlling the deflection angle of the linear light, a beam expanding module 8 for covering the scanning surface of the linear light onto the surface of a digital micromirror array 9, a digital micromirror array 9 for pattern modulation of the linear light, and a processing module for imaging the modulated linear light onto the focal plane for direct writing processing.

[0024] In this invention, the shaping module includes a Powell prism 2, which shapes the laser light generated by the laser 1 into a linear beam. The linear beam is then collimated by a cylindrical lens 3 to straighten the divergence angle introduced by the Powell prism 2, thus forming a collimated beam with a linear cross-section.

[0025] The cylindrical lens 3 of the present invention is at least one, in Figure 1 In this invention, a single laser beam is used, in which case the laser shaping effect is better as a linear light.

[0026] The shaped linear light is then deflected by AOD (6) and the scanning surface is covered by the beam expansion module 8 to make the scanning surface cover the surface of DMD (9). Then, a one-dimensional scan is performed on the surface of DMD (9).

[0027] AOD controls the deflection direction of the linear beam, and the scanning direction is perpendicular to the linear beam.

[0028] The digital micromirror array (DMD) of this invention comprises multiple independently controllable sub-micromirrors, reaching hundreds of thousands in number, which can be used as dynamic masks to generate arbitrary inscription patterns and modulate the scanning linear light. Each sub-micromirror of the DMD can be independently switched on and off, and in conjunction with linear light scanning, a single one-dimensional scan can complete the scanning and inscription of a two-dimensional pattern.

[0029] The processing module of the present invention includes a lens 10 and an objective lens 11 arranged sequentially, which constitute a 4F system. A linear beam encoded and modulated by DMD (9) is conjugated to the focal plane of the objective lens 11 through the 4F system composed of lens 10 and objective lens 11 for laser writing processing. The processing module also includes a writing platform 12 disposed behind the objective lens 11, on which laser writing processing is performed.

[0030] The linear light modulated by DMD is conjugated to the focal plane of the objective lens by the 4F system consisting of lens 2 and objective lens for laser direct writing.

[0031] The deflection angle of AOD satisfies an approximate relationship. ,in The wavelength of light For sound wave frequency, Let $\frac{1}{2}$ be the speed of sound propagation in the crystal. Therefore, light of different wavelengths will have different deflection angles after passing through an AOD (Alternating Dispersion Device), making the AOD essentially a dispersive device. Continuous light sources have extremely narrow spectra, with different spectral components almost completely overlapping, so dispersion can be considered nonexistent, and dispersion compensation is unnecessary. However, femtosecond lasers have wider spectra, and after passing through an AOD, they will produce a significant spatial dispersion effect. Therefore, when using a femtosecond laser as a light source, dispersion compensation must be considered. See also... Figure 2 The beam distributions of the yz and xz cross sections are shown respectively. This invention provides a high-throughput laser direct writing device comprising a laser (a femtosecond laser) 1, a Powell prism 2, a cylindrical lens 3, a triangular prism 4, a reflector 5, an acousto-optic deflector 6, a lens group 7, a beam expander 8, a digital micromirror array 9, a lens 10, an objective lens 11, and a writing platform 12.

[0032] The femtosecond laser dispersion caused by AOD is compensated by introducing a triangular prism 4 and a lens group 7. The lens group 7 can consist of multiple lenses, as long as they can achieve the effect of compensating for the femtosecond laser dispersion caused by AOD, typically 2 to 3 lenses. The reflector 5 is used to change the direction of the light path, so that the outgoing light path after passing through the triangular prism can be collimated and enter the acousto-optic deflector 6.

[0033] Example 1 Using a circular laser spot with a diameter of 1 mm, and selecting a Powell prism with a divergence angle of 30°, the divergence angle formula is applied. At a distance of z = 8 mm, a linear beam with a length of L = 4.3 mm can be obtained. Therefore, a cylindrical lens with a focal length of 8 mm can be selected to correct its divergence angle. Subsequently, a beam expander module composed of two cylindrical lenses can be used to expand the long axis of the linear beam by a factor of 3, thereby correcting the beam into a linear beam with a cross-section of 12.9 mm × 1 mm.

[0034] Taking the DMD of Texas Instruments DLP9500 as an example, the number of micromirrors is 1920×1080, the diameter of the sub-micromirrors is 10.8 micrometers, and the target surface size is 11.7mm×20.7mm. Then the linear light scanning area can effectively cover the surface of the DMD.

[0035] AOD scan rate can reach 10 7 At Hz, a single line during scanning corresponds to the switching information carried by 1080 sub-micromirrors. Using a 40x objective lens, a processing area of ​​292.5 μm × 517.5 μm can be achieved in a single scan, with a single scan time of only 0.1 μs and a processing throughput of 1.08 × 10⁻⁶. 10 The single-channel laser direct writing system takes 151 seconds to process the same area (292.5 μm × 517.5 μm) at a scanning speed of 10 mm / s.

[0036] It is evident that this method can shorten the processing time by 1.5 × 10⁻⁶. 10 This can significantly improve processing efficiency.

[0037] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A high-throughput laser direct writing device, characterized in that, The system includes a laser arranged sequentially along the optical path, a shaping module for shaping the beam into linear light, an acousto-optic deflector for controlling the deflection angle of the linear light, a beam expanding module for covering the scanning surface of the linear light onto the surface of a digital micromirror array, the digital micromirror array for pattern modulation of the linear light, and a processing module for imaging the modulated linear light onto the focal plane for direct writing processing.

2. The high-throughput laser direct writing device according to claim 1, characterized in that, The shaping module includes a Powell prism for shaping the laser emitted by the laser into linear light.

3. The high-throughput laser direct writing device according to claim 2, characterized in that, The shaping module also includes at least one cylindrical lens for collimating the linear light emitted from the Powell prism to form a collimated beam with a linear cross-section.

4. The high-throughput laser direct writing device according to claim 1, characterized in that, The digital micromirror array includes multiple independently controllable sub-micromirrors used as dynamic masks to modulate the scanned linear light.

5. The high-throughput laser direct writing device according to claim 1, characterized in that, The processing module includes a lens and an objective lens arranged in sequence. The lens and the objective lens constitute a 4F system, which is used to conjugate the linear beam modulated by the digital micromirror array onto the focal plane of the objective lens.

6. The high-throughput laser direct writing device according to claim 1, characterized in that, The processing module also includes an inscription platform located behind the objective lens.

7. The high-throughput laser direct writing device according to claim 1, characterized in that, When the laser is a femtosecond laser, the high-throughput laser direct writing device further includes a dispersion compensation element for compensating for the dispersion caused by the acousto-optic deflector, which is disposed in the input and output optical paths of the acousto-optic deflector.

8. The high-throughput laser direct writing device according to claim 7, characterized in that, The dispersion compensation element includes a triangular prism and a lens group; The triangular prisms are sequentially positioned in front of the acousto-optic deflector, and the linear light passes through the triangular prisms and the reflector in sequence before being collimated into the acousto-optic deflector.

9. The high-throughput laser direct writing device according to claim 8, characterized in that, The dispersion compensation element also includes a reflector for changing the direction of the light path, the reflector being disposed between the triangular prism and the acousto-optic deflector.

10. A high-throughput laser direct writing method, based on the apparatus according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Shape the laser light generated by the laser into linear light; S2. Control the linear light to be deflected by the acousto-optic deflector, and then pass through the beam expander module so that the scanning surface covers the target surface of the digital micromirror array; S3. Using the independently controllable sub-micromirrors on the digital micromirror array, the linear light scanned to its target surface is dynamically patterned. S4. The modulated linear light is conjugated to its focal plane through the processing module, and laser direct writing is performed in the processing area located on the focal plane.

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