Holographic exposure device with adjustable interference angle

Abstract

The utility model relates to optical device technical field especially relates to a holographic exposure device of interference included angle adjustable, include: laser, beam splitter, set up in the first optical path subassembly and second optical path subassembly of beam splitter side away from laser and substrate sample holder, the first optical path subassembly and second optical path subassembly symmetrical setting, substrate sample holder is located in the meeting place formed by the light beam of first optical path subassembly and the light beam of second optical path subassembly, the first optical path subassembly and second optical path subassembly include laser beam expanding system and tunable mirror group along the light propagation direction, tunable mirror group includes rotary table, set up on the mirror of rotary table and be used for control servo motor of rotary table. Through the rotary table drive mirror rotates and changes the reflection angle, makes the interference angle of two beams of light change, thereby changes the preparation sample wavelength, simultaneously cooperates the position of substrate sample holder, can realize different interference angle and realize preparation wavelength tunable function.

Description

Technical Field

[0001] This utility model relates to the field of optical device technology, and in particular to a holographic exposure device with adjustable interference angle. Background Technology

[0002] Traditional two-beam interferometry requires disassembling and reassembling all components after the initial setup for wavelength tuning. This process is time-consuming and lacks accuracy. Consequently, traditional volume Bragg grating fabrication techniques suffer from complex processes, difficulties in wavelength adjustment, and time-consuming setup.

[0003] Therefore, existing technologies still need to be improved and developed. Utility Model Content

[0004] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a holographic exposure device with adjustable interference angle, which aims to solve the problem that existing holographic exposure devices cannot adjust the interference angle.

[0005] The technical solution of this utility model is as follows: A holographic exposure apparatus with adjustable interference angle includes: a laser, a beam splitter for receiving a laser source emitted by the laser, a first optical path assembly and a second optical path assembly disposed on the side of the beam splitter opposite to the laser, and a substrate sample holder; the first optical path assembly and the second optical path assembly are symmetrically arranged; the substrate sample holder is located at the intersection formed by the beams from the first optical path assembly and the second optical path assembly. Both the first optical path component and the second optical path component include a laser beam expander and a tunable mirror group along the light propagation direction; the tunable mirror group includes a turntable, a mirror disposed on the turntable, and a servo motor for controlling the turntable.

[0006] The holographic exposure device with adjustable interference angle, wherein the linewidth of the laser source is ≤1MHz and the wavelength of the laser source is between 150nm and 400nm.

[0007] The holographic exposure device with adjustable interference angle, wherein the laser beam expanding system is a Keplerian structure or a Galilean structure.

[0008] The holographic exposure apparatus with adjustable interference angle, wherein the magnification of the laser beam expanding system is between 2 and 400 times.

[0009] In the aforementioned holographic exposure device with adjustable interference angle, the reflector is used to reflect the full beam of the laser beam expander system.

[0010] The holographic exposure device with adjustable interference angle includes a controller for controlling the operation of the servo motor.

[0011] The holographic exposure apparatus with adjustable interference angle includes a turntable comprising a base and a turntable rotatably connected to the base via gears; the reflector is disposed on the turntable.

[0012] The holographic exposure device with adjustable interference angle is wherein the reflector is fixed to the turntable by a fixing member; the adjustment accuracy of the turntable is less than 3″.

[0013] The holographic exposure apparatus with adjustable interference angle further includes a ball screw linear guide rail; the substrate sample holder is located on the ball screw linear guide rail and is slidably connected; the ball screw linear guide rail is perpendicular to the common plane of the tunable mirror group of the first optical path component and the tunable mirror group of the second optical path component.

[0014] In the holographic exposure apparatus with adjustable interference angle, the angle between the tunable mirror group of the first optical path component and the common plane of the tunable mirror group of the second optical path component and the common plane are complementary.

[0015] Beneficial Effects: This utility model provides a holographic exposure device with adjustable interference angle, comprising: a laser, a beam splitter for receiving laser light emitted by the laser, a first optical path assembly and a second optical path assembly disposed on the side of the beam splitter opposite to the laser, and a substrate sample holder; the first optical path assembly and the second optical path assembly are symmetrically arranged; the substrate sample holder is located at the intersection formed by the beams of the first optical path assembly and the second optical path assembly; both the first optical path assembly and the second optical path assembly include a laser beam expander and a tunable mirror assembly along the light propagation direction; the tunable mirror assembly includes a turntable, a mirror disposed on the turntable, and a servo motor for controlling the turntable. This invention is based on a tunable reflector assembly at both arms of the interference optical path. The reflector is rotated by the turntable to change the reflection angle, thereby changing the interference angle of the two beams and thus changing the wavelength of the prepared sample. In conjunction with the position of the substrate sample holder, different interference angles and tunable wavelengths can be achieved. Furthermore, this holographic exposure device has a simple structure and can directly change the interference angle to adjust the wavelength without rebuilding the interference field, reducing the uncertainty and setup time and cost in the debugging and preparation process. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a holographic exposure device with adjustable interference angle according to the present invention; Figure 2 This is a schematic diagram of the tunable mirror assembly. Figure 3 A schematic diagram illustrating the relationship of the interference angle adjustment; Explanation of reference numerals in the attached drawings: Laser 10, Beam splitter 20, Substrate sample holder 30, Laser beam expander system 40, Collimating lens 41, Tunable mirror assembly 50, Turntable 51, Base 511, Turntable 512, Mirror 52, Fixing component 53, Ball screw linear guide 60. Detailed Implementation

[0017] This invention provides a holographic exposure device with adjustable interference angle. To make the purpose, technical solution, and effects of this invention clearer and more explicit, the following provides a more detailed description of this invention. It should be understood that the specific embodiments described herein are merely illustrative of this invention and are not intended to limit this invention.

[0018] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," and "rear," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features.

[0019] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0020] like Figure 1As shown, this utility model provides a holographic exposure device with adjustable interference angle, including: a laser 10, a beam splitter 20 for receiving the laser source emitted by the laser 10, a first optical path assembly and a second optical path assembly disposed on the side of the beam splitter 20 away from the laser 10, and a substrate sample holder 30; the first optical path assembly and the second optical path assembly are symmetrically arranged; the substrate sample holder 30 is located at the intersection formed by the beams of the first optical path assembly and the second optical path assembly; Both the first optical path assembly and the second optical path assembly include a laser beam expander system 40 and a tunable mirror group 50 along the light propagation direction; for example Figure 2 As shown, the tunable reflector assembly 50 includes a turntable 51, a reflector 52 disposed on the turntable 51, and a servo motor (not shown) for controlling the turntable 51.

[0021] In this embodiment, based on the tunable reflector group at both arms of the interference optical path, the reflector is rotated by the turntable to change the reflection angle, thereby changing the interference angle of the two beams and thus changing the wavelength of the prepared sample. At the same time, in conjunction with the position of the substrate sample holder, different interference angles and the function of tunable preparation wavelength can be realized. Furthermore, this holographic exposure device has a simple structure and can directly change the interference angle to adjust the preparation wavelength without rebuilding the interference field, reducing the uncertainty and setup time cost in the debugging and preparation process.

[0022] Specifically, this invention splits a laser beam into two paths, which are then expanded and reflected separately, ultimately converging in space to form an interference field that acts on a substrate sample holder. Simultaneously, by controlling the angles and phases of the tunable mirror groups in the first and second optical path components, periodic nanostructures are etched onto the substrate fixed to the sample holder. In other words, by utilizing a laser, beam splitter, first optical path components, and second optical path components to generate two high-quality and highly uniform collimated parallel beams, and by using the tunable mirror groups to adjust the interference angle and the position of the substrate sample holder, high-precision and uniform exposure of arbitrary periodic nanostructures on the substrate sample holder is achieved.

[0023] In some embodiments, the linewidth of the laser source is ≤1MHz, and the wavelength of the laser source is between 150nm and 400nm. The generation of ultraviolet laser with good monochromaticity and long coherence length for exposure using this laser, with both the linewidth and wavelength within the aforementioned range, forms the basis of the energy and coherence of the entire device. Specifically, the laser light is first incident into the beam splitter and then precisely split into two beams of equal intensity and perpendicular propagation direction, serving as the starting point for forming two-beam interference.

[0024] In a preferred embodiment, the wavelength of the laser source is between 270nm and 360nm.

[0025] In some embodiments, the laser beam expander system is a Keplerian or Galilean structure.

[0026] In some embodiments, the magnification of the laser beam expander system is between 2 and 400 times.

[0027] In some embodiments, the laser beam expander system 40 consists of a lens and a pinhole filter. Its function is not only to expand the diameter of the laser beam, but more importantly, to perform spatial filtering through the pinhole filter to remove optical noise, thereby obtaining a quasi-ideal Gaussian beam with a perfect wavefront and uniform intensity distribution, laying the foundation for obtaining uniform interference fringes in the future.

[0028] Specifically, the lens surface in the laser beam expander system is coated with an anti-reflection film, with a transmittance of ≥95% at the ultraviolet laser wavelength. This allows the expanded divergent beam to be efficiently converted into large-aperture parallel light, while ensuring the consistency of the light intensity of the two beams, which is crucial for the contrast of the interference fringes.

[0029] In some embodiments, the laser beam expander system 40 further includes a collimating lens 41.

[0030] In some embodiments, the reflector is used to reflect the full beam of the laser beam expander system.

[0031] In a preferred embodiment, the reflector is rectangular in shape; the dimensions of the reflector are (180mm-250mm) × (90mm-150mm).

[0032] In some embodiments, the tunable reflector assembly further includes a controller (not shown) for controlling the operation of the servo motor.

[0033] In a preferred embodiment, the tunable reflector group consists of a metal film reflector with a length × width of 200mm × 100mm and a high-precision turntable driven by a servo motor. The function of the tunable reflector group is to perform high-precision pointing control of the light beam. By controlling the turntable to rotate precisely by an angle θ, the reflection angle of the light beam can be changed, thereby ultimately changing the intersection angle α of the two beams in the interference field, and realizing the continuous tunability of the interference fringe period.

[0034] In some embodiments, the controller includes, but is not limited to, a programmable logic controller (PLC); for example, it includes, but is not limited to, one of ABB PM825, ABB PM865K01, and Velocio Ace 1430. Preferably, the controller is pre-stored with a control program for the turntable at the factory. By inputting the deflection angle θ of the turntable into the controller, precise rotation of the turntable can be achieved. Alternatively, by pre-storing an existing algorithm for the deflection angle θ into the controller, and by inputting a known value, the algorithm in the controller automatically obtains the deflection angle θ, thereby achieving control of the turntable.

[0035] In some implementations, such as Figure 2 As shown, the turntable 51 includes a base 511 and a turntable 512 rotatably connected to the base 511 via gears; the reflector 52 is disposed on the turntable 512. The base 511 and the turntable 512 form a rotating structure, and the servo motor drives the gears to rotate, thereby causing the turntable to rotate at a certain angle, thus adjusting the angle of the reflector.

[0036] In some implementations, such as Figure 2 As shown, the reflector 52 is fixed to the turntable 51 by a fixing member 53; the adjustment accuracy of the turntable 51 is less than 3″. Fixing the reflector with a fixing member can improve the stability of the reflector; while setting a grating ruler feedback device can improve the rotation accuracy of the tunable reflector assembly.

[0037] In a preferred embodiment, the turntable 51 is provided with a grating ruler feedback element, and the subdivision accuracy of the grating ruler feedback element is 1 arcsecond.

[0038] In some implementations, such as Figure 1 As shown, the holographic exposure apparatus further includes a ball screw linear guide 60; the substrate sample holder 30 is located on the ball screw linear guide 60 and is slidably connected; the ball screw linear guide 60 is perpendicular to the common plane of the tunable mirror group of the first optical path component and the tunable mirror group of the second optical path component. The substrate sample holder 30 is located at the converging center of the two interference light paths. The ball screw linear guide is used to precisely control the movement of the substrate sample holder along a one-dimensional direction. This displacement is used to accurately position the substrate on the substrate sample holder in the interference field after angle adjustment, ensuring accurate exposure area, and can be used to achieve phase-stepping or multi-channel stitching exposure.

[0039] In some embodiments, a stepper motor (not shown) is mounted on the ball screw linear guide 60 to control the movement of the substrate sample holder on the ball screw linear guide; the stepper motor is controlled by the controller. Precise movement of the substrate sample holder can be achieved by inputting the displacement d of the substrate sample holder to the controller. Alternatively, by pre-storing an existing algorithm for the displacement d to the controller, and by inputting a known value, the algorithm in the controller automatically obtains the displacement d, thereby achieving control of the substrate sample holder.

[0040] Specifically, when the holographic exposure device needs to change the target exposure wavelength or fringe period, the controller in the tunable mirror group calculates the angle θ that the mirror needs to rotate according to the optical formula, and then controls the servo motor to drive the turntable to rotate synchronously by angle θ, thereby precisely adjusting the interference angle from the reference angle β to the target angle α; the accuracy of 1 arcsecond ensures the ultimate precision of angle control; at the same time, the rotation of the mirror angle will cause a slight shift in the interference field in space. At this time, the substrate sample holder needs to be moved by a corresponding displacement d through the ball screw linear guide rail, so that the substrate is always at the center of gravity position where the interference field energy is strongest and the fringes are clearest.

[0041] In some embodiments, the angle between the tunable mirror group of the first optical path component and the common plane of the tunable mirror group of the second optical path component is complementary to the angle between the tunable mirror group of the first optical path component and the common plane.

[0042] In some embodiments, the substrate on the substrate sample holder is a PTR (photothermal refractive glass) substrate.

[0043] To more clearly illustrate the principle of interference angle adjustment in the holographic exposure device of this invention, a schematic diagram of the interference angle adjustment relationship is shown below. Figure 3 As shown in the diagram, this schematic clearly illustrates the ultraviolet laser interference optical path adjustment model based on two tunable mirror groups. First, Figure 3 In this context, β (origin exposure angle) is the reference angle for initial calibration of the device. It defines the initial angle between the central axis of the interference field formed after the ultraviolet laser beam is reflected by the mirror and the optical reference axis. Secondly, α (target exposure angle) is the final target to be achieved, i.e., the target direction in which the central axis of the interference field must point to achieve a specific target wavelength or ideal interference conditions. θ (rotation angle of the turntable containing the mirror) serves as the bridge connecting the starting point and the target, representing the angle value at which the turntable needs to rotate synchronously to achieve the transition from β to α. These three elements form a set relationship of α = β + θ, meaning that by precisely controlling the turntable rotation angle θ, the system's exposure angle can be linearly changed from the initial calibration value β to the target value α.

[0044] In addition to the angle parameter, H (beam offset distance) refers to the perpendicular distance in space between the center of the ultraviolet laser beam spot after reflection by the mirror and the central axis of the interference field. It directly reflects the collimation state and mirror symmetry of the optical path. d refers to the translation distance of the substrate relative to the initial calibration position (origin 0). After the angle adjustment is completed, it is usually necessary to fine-tune the position d of the substrate to compensate for the possible spot position shift caused by the angle change, thereby ensuring that the interference pattern falls precisely on the expected position of the substrate.

[0045] In this embodiment, the adjustment process of the entire device is as follows: β is determined from the initial calibration, the target α is calculated, and then the turntable is driven to rotate by an angle θ to complete the core angle change. Finally, the substrate (d) is translated according to the optical path (H) for precise positioning compensation. The rotation of the turntable and the linear displacement of the substrate work together to achieve precise control of the exposure angle and position, thus meeting the requirements of high-quality interferometric exposure tuning.

[0046] For example, using ultraviolet exposure wavelength as =325nm, target fabrication wavelength is Taking 975nm as an example, the details are as follows: Step 1: Based on the grating equation Where n is the average refractive index of the photothermal refractive material, n=1.498, the exposure angle is obtained as β=29.955°, the center point of convergence of the two beams of light is the origin 0, and at this time the substrate sample holder coincides with the origin 0.

[0047] Step 2: Fix the PTR substrate onto the substrate sample holder and expose it to a certain dose of ultraviolet light; Step 3: Place the UV-exposed sample in a Magee furnace for development at 500-550℃; Step 4: The wavelength of the fabricated grating can be obtained through testing. =975.8nm; Step 5: Use the existing wavelength =975.8nm adjusted to the target fabrication wavelength =975nm, the required exposure angle can be calculated using the following formula. ;

[0048] According to the required angle and current interference angle The turntable adjustment range of the first optical path component and the second optical path component can be obtained as follows: for ; The distance between the center of the mirror and the central axis of the interference field is H, and the displacement distance of the linear guide rail from the origin 0 of the exposure interference center to the new exposure interference center is... Calculated as ; Step 6: Repeat steps 2 and 3 to obtain a volume Bragg grating with a wavelength of 976nm.

[0049] It should be noted that this process can be obtained based on known conditions. and d Then and d The input is entered into the controller to adjust the turntable and substrate sample holder; alternatively, the process can be automatically calculated by an algorithm pre-stored in the controller.

[0050] In summary, the present invention provides a holographic exposure device with adjustable interference angle, comprising: a laser, a beam splitter for receiving laser light emitted by the laser, a first optical path assembly and a second optical path assembly disposed on the side of the beam splitter opposite to the laser, and a substrate sample holder; the first optical path assembly and the second optical path assembly are symmetrically arranged; the substrate sample holder is located at the intersection formed by the beams of the first optical path assembly and the second optical path assembly; both the first optical path assembly and the second optical path assembly include a laser beam expander and a tunable mirror assembly along the light propagation direction; the tunable mirror assembly includes a turntable, a mirror disposed on the turntable, and a servo motor for controlling the turntable. This invention is based on a tunable reflector assembly at both arms of the interference optical path. The reflector is rotated by the turntable to change the reflection angle, thereby changing the interference angle of the two beams and thus changing the wavelength of the prepared sample. In conjunction with the position of the substrate sample holder, different interference angles and tunable wavelengths can be achieved. Furthermore, this holographic exposure device has a simple structure and can directly change the interference angle to adjust the wavelength without rebuilding the interference field, reducing the uncertainty and setup time and cost in the debugging and preparation process.

[0051] It should be understood that the application of this utility model is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A holographic exposure device with adjustable interference angle, characterized in that, include: A laser, a beam splitter for receiving laser light emitted by the laser, a first optical path assembly and a second optical path assembly disposed on the side of the beam splitter opposite to the laser, and a substrate sample holder; the first optical path assembly and the second optical path assembly are symmetrically arranged; the substrate sample holder is located at the intersection formed by the beams from the first optical path assembly and the second optical path assembly; Both the first optical path component and the second optical path component include a laser beam expander and a tunable mirror group along the light propagation direction; the tunable mirror group includes a turntable, a mirror disposed on the turntable, and a servo motor for controlling the turntable.

2. The holographic exposure apparatus with adjustable interference angle according to claim 1, characterized in that, The linewidth of the laser source is ≤1MHz, and the wavelength of the laser source is between 150nm and 400nm.

3. The holographic exposure apparatus with adjustable interference angle according to claim 1, characterized in that, The laser beam expander system is either a Keplerian or Galilean structure.

4. The holographic exposure apparatus with adjustable interference angle according to claim 1, characterized in that, The magnification of the laser beam expander system is between 2 and 400 times.

5. The holographic exposure apparatus with adjustable interference angle according to claim 1, characterized in that, The reflector is used to reflect the full beam of the laser beam expander system.

6. The holographic exposure apparatus with adjustable interference angle according to claim 1, characterized in that, The tunable reflector assembly also includes a controller for controlling the operation of the servo motor.

7. The holographic exposure apparatus with adjustable interference angle according to claim 1, characterized in that, The turntable includes a base and a turntable rotatably connected to the base via gears; the reflector is disposed on the turntable.

8. The holographic exposure apparatus with adjustable interference angle according to claim 1, characterized in that, The reflector is fixed to the turntable by a fastener; the adjustment accuracy of the turntable is less than 3″.

9. The holographic exposure apparatus with adjustable interference angle according to claim 1, characterized in that, The holographic exposure apparatus further includes a ball screw linear guide; the substrate sample holder is located on the ball screw linear guide and is slidably connected; the ball screw linear guide is perpendicular to the common plane of the tunable mirror group of the first optical path component and the tunable mirror group of the second optical path component.

10. The holographic exposure apparatus with adjustable interference angle according to claim 1, characterized in that, The angle between the tunable mirror group of the first optical path component and the common plane of the tunable mirror group of the second optical path component and the common plane are complementary to each other.

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