Laser wavelength measurement system based on Fizeau interferometer

Abstract

The invention relates to the technical field of laser detection, in particular to a laser wavelength measurement system based on a Fizeau interferometer, which comprises a Galileo beam expanding module, an attenuation piece, a Fizeau interference module, a linear array CMOS camera and a data processing module, wherein the Galileo beam expanding system is composed of a double-agglutination achromatic negative lens and a double-agglutination achromatic lens, the five-time beam expanding function is achieved on incident laser, and the influence of chromatic aberration in the broadband range is reduced; to-be-detected laser passes through the beam expanding system, passes through the attenuation piece and then enters the Fizeau interference module to be interfered, and an interference image is collected by the photoelectric imaging sensor and then is subjected to subsequent operation by the upper computer; the invention can provide a laser wavelength measuring device which is free of a moving device inside, wide in measuring range and low in cost for a laser in a wave band range of 633-852 nm.

Description

Technical Field

[0001] The present invention relates to the field of laser detection technology, and in particular to a laser wavelength measurement system based on a Fizeau interferometer. Background Art

[0002] In the field of quantum precision measurement, lasers are core components, and their performance directly determines the measurement accuracy and practicality of the system. Lasers exhibit differentiated application value in different spectral bands due to their wavelength specificity. Lasers in the visible to near-infrared bands are widely used in quantum precision measurement systems. Typical application scenarios include: optical path calibration and benchmark measurement of helium-neon lasers (632.8nm), and laser wavelength detection corresponding to atomic energy level transitions such as rubidium (D1 line 794.8nm / D2 line 780.0nm) and cesium (D1 line 894.3nm / D2 line 852.1nm). Traditional laser wavelength measurement methods often have problems such as complex systems, high costs, and limited measurement accuracy, making it difficult to meet the growing demand for quantum precision measurement. Therefore, seeking a laser wavelength measurement method and technology with a simple structure, low cost, and the ability to achieve high-precision measurement has become a key issue that needs to be urgently addressed in this field. Summary of the Invention

[0003] In view of this, the present invention addresses the deficiencies in the prior art and proposes a laser wavelength measurement system based on a Fizeau interferometer, aiming to solve at least one of the problems raised in the above background technology.

[0004] The present invention provides a laser wavelength measurement system based on a Fizeau interferometer, comprising: a laser, a Galilean beam expander module located behind the laser, an attenuation plate located behind the Galilean beam expander module, a Fizeau interferometer module located behind the attenuation plate, a linear array CMOS camera located behind the Fizeau interferometer module, and a data processing module located behind the linear array CMOS camera;

[0005] The Galilean beam expansion module is composed of a double cemented achromatic negative lens and a double cemented achromatic lens;

[0006] The attenuation plate is used to attenuate the light intensity of the laser emitted by the laser;

[0007] The Fizeau interference module is composed of a circular window and an optical wedge, the middle of the Fizeau interference module is glued by a gasket, and the internal filling of the Fizeau interference module is air;

[0008] The linear array CMOS camera is a photoelectric imaging device;

[0009] The data processing module is configured to manually screen effective signals and perform wavelet denoising on the signals, then use the AMPD peak detection algorithm to determine the peak point of the filtered signal, calculate the average fringe spacing by the distance between the first and last peak points and the number of fringes, and calculate the wavelength of the incident laser by the fringe spacing.

[0010] In some embodiments, the outer surface of the Fizeau interferometer module is coated with an anti-reflection film with a wavelength range of 600 to 900 nm.

[0011] In some embodiments, the average fringe spacing is calculated by the distance between the first and last peak points and the number of fringes, and the wavelength of the incident laser is calculated by the fringe spacing, including: the wavelength calculation formula is λ=2neα, where n is the refractive index of air, e is the calculated fringe spacing, and α is the wedge angle.

[0012] In some embodiments, the data processing module is further configured to perform calibration using a reference laser of known wavelength before performing wavelength measurement, and the calibrated wavelength is calculated by λ=e·λ0 / e0, where λ is the wavelength of the laser to be measured, e is the spacing of the laser stripes to be measured, λ0 is the wavelength of the reference laser, and e0 is the spacing of the reference laser stripes.

[0013] Compared with existing technologies, the present invention offers the following advantages: The beam expansion system, consisting of a double-cemented achromatic negative lens and a double-cemented achromatic lens, achieves fivefold beam expansion of the input laser, facilitating the acquisition of interference fringes. The Fizeau interferometer module, composed of a circular window and an optical wedge, causes laser light to interfere on the upper and lower surfaces of the air wedge, with a linear array CMOS camera capturing the interference image and light intensity curve. The incident laser light can be measured by processing the light intensity signal. The overall system features no internal moving components, a simple structure, a wide measurement band, and low cost.

[0014] The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure.

[0015] Other features and aspects of the present disclosure will become more apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A structural diagram of a laser wavelength measurement system based on a Fizeau interferometer provided in an embodiment of the present invention;

[0018] Figure 2 A structural diagram of a Fizeau interferometer module of a laser wavelength measurement system based on a Fizeau interferometer provided in an embodiment of the present invention;

[0019] Figure 3 Flowchart of a laser wavelength measurement system based on Fizeau interferometer provided in an embodiment of the present invention.

[0020] Among them: 1. Laser; 2. Double-cemented achromatic negative lens; 3. Double-cemented achromatic lens; 4. Attenuation plate; 5. Fizeau interferometer module; 6. Linear array CMOS camera; 7. Data processing module; 1-1. Circular window; 1-2. Optical wedge. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0022] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0023] 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 the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0025] See Figure 1-3 As shown, a laser wavelength measurement system based on a Fizeau interferometer according to an embodiment of the present application includes: a laser 1, a Galilean beam expander module located behind the laser 1, an attenuation plate 4 located behind the Galilean beam expander module, a Fizeau interferometer module 5 located behind the attenuation plate 4, a linear array CMOS camera 6 located behind the Fizeau interferometer module 5, and a data processing module 7 located behind the linear array CMOS camera 6;

[0026] The Galilean beam expansion module is composed of a double cemented achromatic negative lens 2 and a double cemented achromatic lens 3;

[0027] The attenuation plate 4 is used to attenuate the light intensity of the laser emitted by the laser 1;

[0028] The Fizeau interference module 5 is composed of a circular window 1-1 and an optical wedge 1-2. The middle of the Fizeau interference module 5 is glued together by a gasket, and the internal filling of the Fizeau interference module 5 is air.

[0029] The linear array CMOS camera 6 is a photoelectric imaging device;

[0030] The data processing module 7 is configured to manually screen the effective signals and perform wavelet denoising on the signals, then use the AMPD peak detection algorithm to determine the peak point of the filtered signal, calculate the average fringe spacing by the distance between the first and last peak points and the number of fringes, and calculate the wavelength of the incident laser by the fringe spacing.

[0031] Specifically, the Galilean beam expansion module consists of a double-cemented achromatic negative lens 2 and a double-cemented achromatic lens 3, achieving a five-fold beam expansion of the incident laser. Its double-cemented nature can reduce the impact of chromatic aberration over a wide wavelength range.

[0032] Attenuation plate 4 is used to attenuate the laser light intensity. Linear array CMOS camera 6 experiences saturation when the light intensity reaches a threshold, making it difficult to discern interference fringes. After passing through the attenuation plate, the light intensity is weakened, allowing linear array CMOS camera 6 to capture the complete interference fringes. Fizeau interferometer module 5 consists of a circular window 1-1 and a slightly angled optical wedge 1-2.

[0033] The data processing module 7 is configured to manually screen effective signals and perform wavelet denoising on the signals, which can effectively suppress background noise while retaining the signal peak characteristics. The AMPD peak detection algorithm is then used to determine the peak point of the filtered signal. The average fringe spacing is calculated by the distance between the first and last peak points and the number of fringes, and the wavelength of the incident laser is calculated by the fringe spacing.

[0034] The Fizeau interferometer module 5 consists of a circular window 1-1 and an optical wedge 1-2, glued together with a gasket in the middle. The module is filled with air, and the laser is reflected from the upper and lower surfaces of the air wedge. To enhance laser transmittance, an antireflection coating is applied to the outer surfaces of the Fizeau interferometer module 5. The coating has a wavelength range of 600 to 900 nm and a transmittance of approximately 95%. To enhance laser reflection in the air gap, an antireflection coating with a transmittance of 30% and a reflectance of 70% is applied to the air wedge surface, which enhances the intensity of optical interference. The optical path design ensures that the expanded and collimated laser enters the Fizeau interferometer module at an angle of incidence of 0°, meaning that the light is incident as perpendicularly as possible to the surface.

[0035] The linear array CMOS camera 6 is a photoelectric imaging device that can capture images of interference fringes and record light intensity curves. The fringe spacing can be calculated based on the light intensity peak point.

[0036] In some specific embodiments, the outer surface of the Fizeau interferometer module 5 is coated with an anti-reflection film, and the wavelength range is 600 to 900 nm.

[0037] In some specific embodiments, the average fringe spacing is calculated by the distance between the first and last peak points and the number of fringes, and the wavelength of the incident laser is calculated by the fringe spacing, including: the wavelength calculation formula is λ=2neα, where n is the refractive index of air, e is the calculated fringe spacing, and α is the wedge angle.

[0038] In some specific embodiments, the data processing module 7 is further configured to perform calibration using a reference laser of known wavelength before performing wavelength measurement, and the calibrated wavelength is expressed by λ=e·λ0 / e0, where λ is the wavelength of the laser to be measured, e is the spacing of the laser stripes to be measured, λ0 is the wavelength of the reference laser, and e0 is the spacing of the reference laser stripes.

[0039] It should be understood that the laser emitted by the laser 1 first passes through a Galilean beam expansion module (composed of a double-cemented achromatic negative lens 2 and a double-cemented achromatic lens 3) to achieve five-fold beam expansion. The purpose of beam expansion is to increase the laser spot size to facilitate the subsequent collection and analysis of interference fringes, while reducing the influence of chromatic aberration within a wide band and improving the measurement accuracy of the system. The expanded laser passes through an attenuation plate 4 for light intensity attenuation. Since the linear array CMOS camera 6 will saturate when the light intensity is too high, resulting in the inability to distinguish the interference fringes, the light intensity is adjusted to an appropriate range through the attenuation plate 4 to ensure that the camera can collect complete interference fringes. The attenuated laser enters the Fizeau interferometer module 5. The module consists of a circular window 1-1 and an optical wedge 1-2, which are glued together by a gasket in the middle and filled with air. The laser is reflected on the upper and lower surfaces of the air wedge to form interference fringes. To enhance the transmittance and reflectivity of the laser, the outer surface of the Fizeau interferometer module 5 is coated with an antireflection coating (wavelength range 600-900nm, transmittance approximately 95%). The surface of the air wedge is coated with an antireflection coating with a transmittance of 30% and a reflectance of 70% to enhance interference intensity. The interference fringes are captured by a linear array CMOS camera, and the light intensity curve is recorded. Because the laser is incident perpendicularly to the Fizeau interferometer module 5 at an angle of incidence of 0°, the interference fringes are clear and easy to analyze.

[0040] This system has no moving components and a simple structure, avoiding the errors caused by the complex mechanical adjustments and moving parts found in traditional interferometers, thereby improving system stability and reliability. The antireflection coating applied to the outer surface of the Fizeau interferometer module 5 covers a wavelength range of 600 to 900 nm, making it suitable for laser measurement from the visible to the near-infrared range. This wide measurement band meets the measurement requirements of a wide range of laser wavelengths. The system uses a linear array CMOS camera 6 as the optoelectronic imaging element, significantly reducing costs compared to traditional high-precision sensors. Furthermore, the system's simple structure eliminates the need for complex optical components or mechanical devices, further reducing costs. A Galilean beam expander module achieves fivefold beam expansion, minimizing chromatic aberration. Attenuators optimize light intensity to ensure clear interference fringes. Wavelet denoising and AMPD peak detection algorithms improve signal processing accuracy, ultimately achieving high-precision laser wavelength measurement. The system's simple structure and clear operational procedures eliminate the need for complex adjustments and calibration. Furthermore, the lack of moving components reduces maintenance costs and failure rates, ensuring long-term stable operation. The system can be widely used in fields such as quantum precision measurement, laser wavelength calibration, and spectral analysis, and is particularly well-suited for scenarios requiring high-precision, low-cost, and wide-band laser wavelength measurement. Based on the principle of the Fizeau interferometer, this application achieves high-precision, low-cost, and wide-band laser wavelength measurement through a simple optical structure and efficient data processing algorithms. The system has a simple structure, high stability, and easy operation, making it suitable for a variety of laser wavelength measurement scenarios and possessing significant technical advantages and application value.

[0041] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A laser wavelength measurement system based on Fizeau interferometer, characterized in that: include: A laser, a Galilean beam expander module located behind the laser, an attenuation plate located behind the Galilean beam expander module, a Fizeau interferometer module located behind the attenuation plate, a linear array CMOS camera located behind the Fizeau interferometer module, and a data processing module located behind the linear array CMOS camera; The Galilean beam expansion module is composed of a double cemented achromatic negative lens and a double cemented achromatic lens; The attenuation plate is used to attenuate the light intensity of the laser emitted by the laser; The Fizeau interference module is composed of a circular window and an optical wedge, the middle of the Fizeau interference module is glued by a gasket, and the internal filling of the Fizeau interference module is air; The linear array CMOS camera is a photoelectric imaging device; The data processing module is configured to manually screen effective signals and perform wavelet denoising on the signals, then use the AMPD peak detection algorithm to determine the peak point of the filtered signal, calculate the average fringe spacing by the distance between the first and last peak points and the number of fringes, and calculate the wavelength of the incident laser by the fringe spacing.

2. The laser wavelength measurement system based on Fizeau interferometer according to claim 1, characterized in that: The outer surface of the Fizeau interferometer module is coated with an antireflection film with a wavelength range of 600 to 900 nm.

3. The laser wavelength measurement system based on Fizeau interferometer according to claim 2, characterized in that: The average fringe spacing is calculated by the distance between the first and last peak points and the number of fringes, and the wavelength of the incident laser is calculated by the fringe spacing. The wavelength calculation formula includes: λ=2neα, where n is the refractive index of air, e is the calculated fringe spacing, and α is the wedge angle.

4. The laser wavelength measurement system based on Fizeau interferometer according to claim 3, characterized in that: The data processing module is further configured to perform calibration using a reference laser of known wavelength before wavelength measurement, and the calibrated wavelength is calculated by λ=e·λ0 / e0, where λ is the wavelength of the laser to be measured, e is the spacing of the laser stripes to be measured, λ0 is the wavelength of the reference laser, and e0 is the spacing of the reference laser stripes.

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