Laser wavelength calibration device suitable for long-optical-path cavity
By utilizing the mirror leakage phenomenon in the laser wavelength calibration device and setting up a reference detector and a reference gas cell, the detection error problem caused by laser wavelength drift is solved, achieving efficient and accurate laser wavelength calibration and improving the signal-to-noise ratio.
Patent Information
- Application Number
- CN202422792343.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-15
- Publication Date
- 2025-11-14
- Estimated Expiration
- 2034-11-15
AI Technical Summary
In existing technologies, laser wavelength drift leads to gas detection errors, and the main detector has weak optical power and poor signal-to-noise ratio after beam splitting, making it difficult to scale up applications.
The method eliminates the need for a separate beam splitter and utilizes the light leakage phenomenon of the mirror coating. The reference detector and reference gas cell are placed behind the reflection point, and the leaked light is used as a reference light source. The laser wavelength is calibrated by using the gas information in the reference gas cell.
It achieves high-efficiency and high-precision calibration of the main laser beam, avoids the introduction of link connectors, improves the signal-to-noise ratio, and is suitable for laser wavelength calibration in long optical path cavities.
Smart Images
Figure CN223551596U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of sensor calibration technology, and more specifically, to a laser wavelength calibration device suitable for long optical path cavities. Background Technology
[0002] In the field of tunable semiconductor laser absorption spectroscopy for gas detection, the requirements for gas detection sensitivity are becoming increasingly stringent. Tunable semiconductor laser absorption spectroscopy technology, combined with a long optical path cavity, increases the effective optical path for gas absorption to achieve high-sensitivity detection. However, the laser's wavelength is affected by external environmental factors, causing drift and resulting in measurement errors.
[0003] Currently, wavelength calibration is achieved using a reference gas chamber sealed with a certain concentration of the target gas and a reference photodetector, through lock-in amplification technology. Specifically, the laser beam is split using a beam splitter (such as a fiber optic splitter or beam splitter). One beam passes through a long optical path to achieve high-sensitivity detection of gas concentration, while the other beam passes through the reference gas chamber sealed with a certain concentration of the target gas and illuminates the reference detector. The laser wavelength is calibrated by extracting the harmonic information of the target gas in the reference gas chamber.
[0004] The system has many link connectors, and the optical power reaching the main detector after being split by the beam splitter is weaker, resulting in a poor signal-to-noise ratio, which is not conducive to large-scale application.
[0005] In order to solve the above problems, people have been seeking an ideal technological solution. Utility Model Content
[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a laser wavelength calibration device suitable for long-path cavities that eliminates the need for a beam splitter path and utilizes the light leakage characteristics of mirror coating to set up a reference detector and reference gas cell, thereby ensuring the power of the main optical path.
[0007] To achieve the above objectives, the technical solution adopted by this utility model is: a laser wavelength calibration device suitable for long optical path cavities, comprising a laser, a main path detector, a reference detector, a reference gas chamber, and an optical cavity;
[0008] The laser serves as a light source, emitting a main laser beam into the optical cavity;
[0009] The optical cavity includes at least two opposing reflective surfaces, which increase the optical path of the main laser beam by reflecting the main laser beam. The reflective surfaces are reflective surfaces that exhibit light leakage.
[0010] The main laser beam forms several reflection points on each reflecting surface. The optical path input side of the reference gas chamber is located on the back side of the reflecting surface corresponding to any reflection point. The reference detector is located on the optical path output side of the reference gas chamber. The light transmitted from the reflection point serves as the reference path light, which passes through the reference gas chamber and reaches the reference detector.
[0011] The main path detector is located at the optical path output end of the optical cavity and is used to receive the main path laser beam.
[0012] Based on the above, the optical cavity is a Herriott cavity, comprising two concave mirrors with concave surfaces facing each other.
[0013] Based on the above, the reflection point corresponding to the installation of the reference gas chamber is one of the first N reflection points of the main laser beam in the optical cavity, where N is less than half of the reflection points in the optical cavity.
[0014] Based on the above, N is less than one-third of the total number of reflection points in the optical cavity.
[0015] Based on the above, the reference detector and the main detector are located on the same side or different sides of the optical cavity.
[0016] Based on the above, the optical cavity is a White cavity or a multiple reflection cavity.
[0017] Based on the above, the reflection point corresponding to the installation of the reference gas chamber is one of the first N reflection points of the main laser beam in the optical cavity, where N is less than half of the reflection points in the optical cavity.
[0018] Based on the above, N is less than one-third of the total number of reflection points in the optical cavity.
[0019] Based on the above, the reference detector and the main detector are located on the same side or different sides of the optical cavity.
[0020] Based on the above, the reflective surface is a coated reflective surface.
[0021] This utility model has substantial features and progress compared to the prior art. Specifically, this utility model has the following advantages:
[0022] This solution utilizes the fact that most concave mirrors on the market are manufactured using a coating process, which results in a certain degree of light leakage, a physical phenomenon that is currently difficult to overcome with technology. Furthermore, laser light has a relatively high intensity, leading to a higher degree of light leakage compared to ordinary light. By combining these factors, a reference detector is installed behind the reflection point, using the leaked light as the light source for the reference detector. This completely avoids the introduction of the link connector, preserves the high efficiency and high precision of the main laser beam, and simultaneously serves the purpose of calibration. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the structure of the laser wavelength calibration device suitable for long optical path cavities in Embodiment 1 of this utility model.
[0024] Figure 2 This is a schematic diagram of the laser wavelength calibration device suitable for long optical path cavities in Embodiment 2 of this utility model.
[0025] Figure 3 This is a schematic diagram of the structure of the laser wavelength calibration device suitable for long optical path cavities in Embodiment 3 of this utility model.
[0026] Figure 4 This is one of the structural schematic diagrams of the laser wavelength calibration device suitable for long optical path cavities in Embodiment 4 of this utility model.
[0027] Figure 5 This is the second schematic diagram of the laser wavelength calibration device suitable for long optical path cavities in Embodiment 4 of this utility model.
[0028] In the diagram: 1. Laser; 2. Main path detector; 3. Reference detector; 4. Reference gas chamber; 5. Optical cavity; 6. White cavity; 7. Multiple reflection cavity. Detailed Implementation
[0029] The technical solution of this utility model will be further described in detail below through specific embodiments.
[0030] like Figure 1 As shown, a laser wavelength calibration device suitable for long optical path cavities includes a laser 1, a main path detector 2, a reference detector 3, a reference gas chamber 4, and an optical cavity 5.
[0031] The laser 1 serves as a light source, emitting the main laser beam into the optical cavity 5.
[0032] The optical cavity 5 includes at least two opposing reflective surfaces. The reflective surfaces are coated reflective surfaces, which increase the optical path of the main laser beam by reflecting the main laser beam. The reflective surfaces are reflective surfaces that have light leakage.
[0033] The main laser beam forms several reflection points on each reflecting surface. The optical path input side of the reference gas chamber 4 is located on the back side of the reflecting surface corresponding to any reflection point. The reference detector 3 is located on the optical path output side of the reference gas chamber. The light transmitted from the reflection point serves as the reference path light, which reaches the reference detector after passing through the reference gas chamber.
[0034] The main path detector is located at the optical path output end of the optical cavity and is used to receive the main path laser beam.
[0035] Example 1
[0036] like Figure 1 As shown, in this embodiment, the optical cavity is a Herriott cavity, which includes two concave mirrors with their concave surfaces facing each other. By adjusting and controlling the operating current and operating temperature of the laser 1, the laser emits light containing the absorption peak wavelength of the gas "fingerprint". The light is reflected multiple times by the Herriott cavity 5 and then shines on the main detector 2, achieving highly sensitive detection of gas concentration.
[0037] Currently, the concave mirror of the Herriott cavity uses a coating process. Due to process performance issues, some light will be transmitted through the mirror. In this embodiment, the transmitted light passes through the reference gas chamber 4, which is filled with standard gas. Finally, the light reaches the reference detector 3, which is converted into an electrical signal by the transimpedance amplification and filtering circuit. The microprocessor extracts the harmonic information of the target gas in the reference gas chamber through lock-in amplification technology to achieve laser wavelength calibration.
[0038] Specifically, the microprocessor determines whether the position of the harmonic information exceeds the set position range. If it does, it controls the laser temperature through a PID algorithm to make the position of the harmonic information conform to the set position range requirements, thereby achieving laser wavelength calibration.
[0039] To improve the light intensity of the reference optical path, the reflection point corresponding to the reference gas chamber is installed as one of the first N reflection points of the main laser beam in the optical cavity, where N is less than half of the reflection points in the optical cavity, and in a more preferred embodiment, N is less than one-third of the total number of reflection points in the optical cavity.
[0040] In this embodiment, the reference chamber is set behind the first emission point, and the reference detector and the main path detector are located on different sides of the optical cavity.
[0041] Example 2
[0042] The main difference between this embodiment and Embodiment 1 is:
[0043] like Figure 2 As shown, the reference detector and the main path detector are located on the same side of the optical cavity, and the reference gas chamber is set behind any of the first few emission points.
[0044] Example 3
[0045] like Figure 3 As shown, the optical cavity is a White cavity 6, comprising three concave mirrors arranged in an M-shape with their concave surfaces facing each other. In other embodiments, the number of concave mirrors can be increased as needed.
[0046] The reference gas chamber is installed at one of the first N reflection points of the main laser beam in the optical cavity. N is less than half of the reflection points in the optical cavity. In a preferred embodiment, N is less than one-third of the total number of reflection points in the optical cavity. In this embodiment, the reference gas chamber 4 is installed on the back of the first few reflection points on the same side of the optical cavity as the main detector.
[0047] In other embodiments, the mirrors can be mounted on different concave mirrors located on different sides of the optical cavity.
[0048] Example 4
[0049] like Figure 4 and Figure 5 As shown, the optical cavity is a multi-reflection cavity 7 with multiple mirrors, and the reference gas chamber 4 is installed on the back of one of the mirrors. Figure 4 and Figure 5 Two installation positions are shown in the diagram.
[0050] In summary, this application utilizes the characteristics of multiple reflections in optical cavities and the objective phenomenon of light leakage in coated reflective materials. By installing the light-leaking area in the reference chamber and using the leaked light as the light source for the reference optical path, the results of the main path detection are calibrated. This avoids the complexity of multi-link structures, resulting in a more streamlined structure and higher efficiency.
[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it; although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of this utility model or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the technical solution claimed by this utility model.
Claims
1. A laser wavelength calibration device suitable for long optical path cavities, characterized in that: Includes laser, main path detector, reference detector, reference gas chamber and optical cavity; The laser serves as a light source, emitting a main laser beam into the optical cavity; The optical cavity includes at least two opposing reflective surfaces, which increase the optical path of the main laser beam by reflecting the main laser beam. The reflective surfaces are reflective surfaces that exhibit light leakage. The main laser beam forms several reflection points on each reflecting surface. The optical path input side of the reference gas chamber is located on the back side of the reflecting surface corresponding to any reflection point. The reference detector is located on the optical path output side of the reference gas chamber. The light transmitted from the reflection point serves as the reference path light, which passes through the reference gas chamber and reaches the reference detector. The main path detector is located at the optical path output end of the optical cavity and is used to receive the main path laser beam.
2. The laser wavelength calibration device suitable for long optical path cavities according to claim 1, characterized in that: The optical cavity is a Herriott cavity, which includes two concave mirrors with their concave surfaces facing each other.
3. The laser wavelength calibration device suitable for long optical path cavities according to claim 2, characterized in that: The reflection point corresponding to the reference gas chamber is one of the first N reflection points of the main laser beam in the optical cavity, where N is less than half of the reflection points in the optical cavity.
4. The laser wavelength calibration device suitable for long optical path cavities according to claim 3, characterized in that: The number N is less than one-third of the total number of reflection points in the optical cavity.
5. The laser wavelength calibration device suitable for long optical path cavities according to claim 3 or 4, characterized in that: The reference detector and the main detector are located on the same side or different sides of the optical cavity.
6. The laser wavelength calibration device suitable for long optical path cavities according to claim 1, characterized in that: The optical cavity is a White cavity or a multiple reflection cavity.
7. The laser wavelength calibration device suitable for long optical path cavities according to claim 6, characterized in that: The reflection point corresponding to the reference gas chamber is one of the first N reflection points of the main laser beam in the optical cavity, where N is less than half of the reflection points in the optical cavity.
8. The laser wavelength calibration device suitable for long optical path cavities according to claim 7, characterized in that: The number N is less than one-third of the total number of reflection points in the optical cavity.
9. The laser wavelength calibration device suitable for long optical path cavities according to claim 7 or 8, characterized in that: The reference detector and the main detector are located on the same side or different sides of the optical cavity.
10. The laser wavelength calibration device suitable for long optical path cavities according to claim 1, characterized in that: The reflective surface is a coated reflective surface.