Coherent noise removing device

Abstract

The invention discloses a coherent noise removing device, and particularly relates to the technical field of optics. The coherent noise removing device comprises a laser light source, an electric control crystal, an electric field control module, a beam expanding lens group, a micro-lens array, a focusing lens group and a CCD camera which are sequentially arranged in the light path direction, the laser light source is a coherent light source and outputs parallel light beams, and the electric control crystal is used for generating refractive index changes and changing the optical path difference of a system. The electric field control module is used for changing the electric field change of the environment where the electric control crystal is located, the refractive index of the electric control crystal is in uniform gradient change along with the change of the electric field environment, then the optical path of the system is changed, the random phase is generated, and coherent noise elimination is achieved. According to the coherent noise removal device provided by the invention, the system can effectively generate random phase change through the electric control crystal and the high-frequency changing electric field, and the fixed phase relation of the coherent noise is destroyed, so that efficient coherent noise elimination is realized.

Description

Technical Field

[0001] The invention relates to the field of optical technology, and in particular to a coherent noise removal device. Background Art

[0002] With the progress of society, the semiconductor industry is developing rapidly. In high-precision equipment such as semiconductor detection equipment or photolithography machines, it is often necessary to use an optical system for illumination, in which the light sources used are various types such as mercury lamps and lasers. In optical systems that require laser illumination, due to the long coherence of the laser, large coherent noise occurs, resulting in poor homogenization of the light spot.

[0003] The traditional method to improve the spot homogenization capability is to increase the bandwidth of the laser or use a rotating scattering plate to eliminate coherent noise. However, the rotating scattering plate is prone to unstable jitter under high-speed rotation, which causes the performance of the optical system to deteriorate. It also has high requirements on the stability of the motor and the stability of rotation, and is costly.

[0004] Therefore, it is necessary to provide a coherent noise removal device to solve the above technical problems. Summary of the invention

[0005] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a coherent noise removal device. Through electrically controlled crystals and high-frequency changing electric fields, the system can effectively generate random phase changes and destroy the fixed phase relationship of coherent noise, thereby achieving efficient coherent noise elimination.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The device for removing coherent noise comprises: a laser light source, an electrically controlled crystal, an electric field control module, a beam expander lens group, a microlens array, a focusing lens group and a CCD camera which are sequentially arranged along an optical path direction, wherein the laser light source is a coherent light source and outputs a parallel light beam, the electrically controlled crystal is used to generate a refractive index change, change the optical path difference of the system and realize a random phase, the electric field control module is used to change the electric field change of the environment in which the electrically controlled crystal is located, and the refractive index of the electrically controlled crystal presents a uniform gradient change with the change of the electric field environment, thereby changing the optical path of the system to generate a random phase and realize the elimination of coherent noise, the beam expander lens group is used to amplify the optical path of the system, the microlens array is used to divide the light beam into sub-units to achieve a uniform light effect, and the focusing lens group converges the parallel light to the focal plane of the CCD camera and forms a uniform light spot.

[0008] Preferably, multiple groups of electrically controlled crystals and electric field control modules may be used to eliminate coherent noise, and the number of electrically controlled crystals corresponds to the number of electric field control modules.

[0009] Preferably, multiple groups of electrically controlled crystals and electric field control modules are used in series.

[0010] Preferably, the length of the electrically controlled crystals of each group of modules or the electric field strength and frequency of the electric field control modules are consistent or inconsistent.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] (1) Through electrically controlled crystals and high-frequency changing electric fields, the system can effectively generate random phase changes, destroying the fixed phase relationship of coherent noise, thereby achieving efficient coherent noise elimination. This is particularly suitable for noise-sensitive application environments such as high-precision optical systems and long-distance laser communications.

[0013] (2) Using a single or multiple sets of electrically controlled crystals and electric field control modules can be flexibly selected according to the actual application scenario to meet different denoising requirements. The use of multiple sets of modules can further enhance the beam phase modulation effect and improve the signal-to-noise ratio and overall performance of the system.

[0014] (3) By adjusting the length of the electrically controlled crystal or the electric field strength and frequency of the electric field control module, the system can optimize the processing of coherent noise with different characteristics, thereby providing a better denoising effect, so that the present invention can adapt to a variety of complex application environments.

[0015] (4) The design of multiple groups of modules not only enhances the denoising effect, but also reduces the impact of the failure of a single group of modules on the performance of the entire system to a certain extent, thereby improving the reliability and stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the coherent noise removal device provided by the present invention.

[0017] Among them, the names corresponding to the figure marks are: 1-laser light source, 2-electrically controlled crystal, 3-electric field control module, 4-beam expander lens group, 5-microlens array, 6-focusing lens group, 7-CCD camera. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The embodiments of the present invention include but are not limited to the following embodiments.

[0019] Example 1

[0020] like Figure 1As shown, the coherent noise removal device provided by the present invention comprises: a laser light source 1, an electrically controlled crystal 2, an electric field control module 3, a beam expander lens group 4, a microlens array 5, a focusing lens group 6 and a CCD camera 7 arranged in sequence along the optical path direction, wherein the laser light source 1 is a coherent light source and outputs a parallel light beam, the electrically controlled crystal 2 is used to produce a refractive index change, change the optical path difference of the system, and realize a random phase, the electric field control module 3 is used to change the electric field change of the environment in which the electrically controlled crystal 2 is located, and the refractive index of the electrically controlled crystal 2 presents a uniform gradient change with the change of the electric field environment, thereby changing the optical path of the system to produce a random phase and realize the elimination of coherent noise, the beam expander lens group 4 is used to amplify the optical path of the system, the microlens array 5 is used to divide the light beam into sub-units to achieve a uniform light effect, and the focusing lens group 6 converges the parallel light to the focal plane of the CCD camera 7 and forms a uniform light spot.

[0021] In this embodiment, the laser light source 1 emits parallel light, and the incident light source passes through the electrically controlled crystal 2. At this time, the electric field control module 3 applies a high-frequency changing electric field to the electrically controlled crystal 2 to change the refractive index of the material, and then expands the beam through the beam expander 4, and then enters the microlens array 5 for homogenization, and finally focuses on the CCD camera 7 by the converging lens group 6. Due to the high-frequency change of the optical path of the system, the coherent noise generated will be superimposed and integrated with each other, and finally present a uniform light spot.

[0022] Example 2

[0023] In a coherent noise removal device, multiple groups of electrically controlled crystals 2 and electric field control modules 3 may be used to eliminate coherent noise, and the number of electrically controlled crystals 2 corresponds to the number of electric field control modules 3 .

[0024] The system using multiple groups of electrically controlled crystals 2 and electric field control modules 2 for coherent noise elimination is to add multiple groups of modules after the first group of electrically controlled crystals 2 and electric field control modules 2 to achieve more thorough coherent noise elimination. By using multiple groups of electrically controlled crystals 2 and electric field control modules 3 in series, the modulation effect of the light beam phase can be further enhanced, thereby more effectively destroying the fixed phase relationship of the coherent noise and achieving a better coherent noise elimination effect. Each group of electrically controlled crystals 2 and electric field control modules 3 independently phase modulates the light beam, so that the phase of the light beam will change randomly after passing through each group of modules, thereby reducing the impact of coherent noise.

[0025] Furthermore, the use of multiple groups of electrically controlled crystals 2 and electric field control modules 3 can also improve the flexibility and adaptability of the system. By adjusting the length of the electrically controlled crystals 2 of each group of modules or the electric field strength and frequency of the electric field control module 3, different coherent noise characteristics can be optimized to achieve better denoising effect.

[0026] The use of multiple groups of modules can also reduce the impact of the failure of a single group of modules on the performance of the entire system to a certain extent, and improve the reliability and stability of the system.

[0027] When a single group or multiple groups of electrically controlled crystals 2 and electric field control modules 3 are used to eliminate coherent noise in the present invention, a decision needs to be made based on multiple factors such as application scenarios, characteristics of coherent noise, and system requirements.

[0028] Application of single set of electrically controlled crystal and electric field control module:

[0029] Simple coherent noise cancellation needs: In some cases, coherent noise may not be serious or have little impact on system performance. In this case, a single set of electrically controlled crystals and electric field control modules may be sufficient to meet the needs without adding additional complexity and cost.

[0030] Preliminary experiment or verification stage: When developing a new optical system or conducting technical verification, a single set of electrically controlled crystals and electric field control modules may be used for preliminary experiments. This helps to quickly evaluate the feasibility and effectiveness of the technology and provides a basis for subsequent optimization and improvement.

[0031] Specific application scenarios: In some specific application scenarios, such as some specific laser communication systems or precision measurement equipment, due to the relatively simple characteristics of the light beam and the propagation path, a single set of electrically controlled crystals and electric field control modules may be able to achieve satisfactory coherent noise elimination effects.

[0032] Application of multiple groups of electrically controlled crystals and electric field control modules:

[0033] Complex coherent noise environment: When the coherent noise is very serious, or there are multiple types of coherent noise, a single set of electrically controlled crystals and electric field control modules may not be able to achieve the ideal elimination effect. In this case, using multiple sets of modules can gradually reduce the coherent noise and improve the signal-to-noise ratio and performance of the system.

[0034] Systems with high precision requirements: In optical systems that require high-precision measurement or control, such as high-resolution imaging, precision positioning, etc., the presence of coherent noise will seriously affect the performance of the system. The use of multiple sets of electrically controlled crystals and electric field control modules can more effectively eliminate coherent noise and improve the stability and reliability of the system.

[0035] Long-distance transmission or complex optical paths: In long-distance laser communications or systems with complex optical paths, the light beam will be affected by various factors during transmission and generate coherent noise. Multiple sets of electrically controlled crystals and electric field control modules can phase modulate the light beam and eliminate coherent noise at different locations, thereby ensuring high-performance operation of the entire system.

Claims

1. A coherent noise removal device, characterized in that: include: A laser light source (1), an electrically controlled crystal (2), an electric field control module (3), a beam expander lens group (4), a microlens array (5), a focusing lens group (6) and a CCD camera (7) are sequentially arranged along an optical path. The laser light source (1) is a coherent light source that outputs a parallel light beam. The electrically controlled crystal (2) is used to generate a refractive index change, change the optical path difference of the system, and achieve a random phase. The electric field control module (3) is used to change the electric field change of the environment in which the electrically controlled crystal (2) is located. As the electric field environment changes, the refractive index of the electrically controlled crystal (2) presents a uniform gradient change, thereby changing the optical path of the system to generate a random phase and achieve the elimination of coherent noise. The beam expander lens group (4) is used to amplify the optical path of the system. The microlens array (5) is used to divide the light beam into sub-units to achieve a uniform light effect. The focusing lens group (6) focuses the parallel light onto the focal plane of the CCD camera (7) and forms a uniform light spot.

2. The coherent noise removal device according to claim 1, characterized in that: Multiple groups of electrically controlled crystals (2) and electric field control modules (3) can be used to eliminate coherent noise, and the number of electrically controlled crystals (2) corresponds to the number of electric field control modules (3).

3. The coherent noise removal device according to claim 2, characterized in that: A plurality of groups of electrically controlled crystals (2) and electric field control modules (3) are used in series.

4. The coherent noise removal device according to claim 2, characterized in that: The length of the electrically controlled crystal (2) or the electric field strength and frequency of the electric field control module (3) of each group of modules are consistent or inconsistent.

Images