CN119534428A - A micro-probe, optical fiber LIBS system and detection method - Google Patents

Abstract

The present application discloses a micro-probe, a fiber-optic LIBS system and a detection method, including an illumination fiber, a laser transmission fiber interface, a laser collimation optical path, a camera imaging optical path, a CMOS imaging sensor, and a CMOS flip control module. The probe is integrated with a fiber-optic LIBS system, which can penetrate into the narrow pipe gaps of a nuclear power plant to perform elemental quantitative analysis and material identification and tracing of foreign matter. The present application implements a fiber-optic LIBS micro-probe with the same optical path for laser focusing and spectrum collection, and by sharing the optical path and flipping the CMOS sensor, it implements the detection process of the camera aiming at the target, the sensor lifting, the laser shooting and returning the spectrum.

Description

Miniature probe, optical fiber type LIBS system and detection method

Technical Field

The application belongs to the technical field of laser-induced breakdown spectroscopy, and relates to a miniature probe, an optical fiber LIBS system and a detection method.

Background

Laser Induced Breakdown Spectroscopy (LIBS) is an atomic optical emission spectroscopy technology mainly used for elemental analysis, and is characterized in that plasma is excited on the surface of a substance by laser, and the spectral line of the element contained in the substance is identified by the plasma emission spectroscopy, so that the element content is quantitatively measured. The existing LIBS technology is mainly divided into a traditional type, an optical fiber type, a telescope type, a handheld type and the like. Fiber laser induced breakdown spectroscopy (FO-LIBS) systems simplify the optical system for laser transmission and plasma spectral collection by fiber optics, replacing the open optical configuration in conventional LIBS. Due to the long-distance optical transmission and spatial flexibility of the optical fiber, FO-LIBS provides a more viable solution for rapid analysis of material composition in confined spaces, occluded, radiated or underwater scenes. FO-LIBS is particularly suitable for severe environments such as nuclear power plants and offshore wind platforms.

In a nuclear power station, radioactive foreign matters with unknown components exist between narrow pipeline gaps (millimeter level) such as steam pipelines, the radioactive foreign matters can influence the normal operation of a nuclear power system, and the radioactive foreign matters need to be manually taken out for chemical component inspection after shutdown, so that efficiency is reduced and economic loss is caused. The FO-LIBS can be used for in-situ, non-stop and real-time element detection of radioactive foreign matters, so as to provide information such as the brand and source of the foreign matters. However, due to the narrow gap, the existing FO-LIBS probe cannot penetrate into a narrow area for detection. Most FO-LIBS probes today do not consider size limitations, where the optical paths of the focused laser and the spectral collection are separate, taking up a significant volume. In addition, most FO-LIBS probes do not take into account that the camera and illumination fibers are also needed to assist in locating the target under test during the probing process, and the size of the slit in the current FO-LIBS probe is necessarily exceeded if the camera and illumination fibers are added. Conventional endoscopes can meet the procedure of access slit monitoring, but cannot be combined with the LIBS system for element detection. The first reason is that the optical system is mainly used for imaging and can not collimate and refocus laser transmitted by the multimode optical fiber, the second LIBS optical feedback spectrum needs a very wide transmission wavelength range of the optical system, most of lenses of the endoscope can not be met, and the third reason is that the laser used by the LIBS is nanosecond pulse laser with higher power and can damage the optical lenses of the endoscope. At present, even though an endoscope is combined with the LIBS, the two optical path systems are separated, and the common optical path is not made, so that the size is reduced.

Disclosure of Invention

The application aims to solve the problems in the prior art and provides a miniature probe, an optical fiber LIBS system and a detection method.

In order to achieve the above purpose, the application is realized by adopting the following technical scheme:

in a first aspect, the present application provides a miniature probe comprising:

The front end of the shell is provided with an illumination optical fiber window and a shared lens, and the tail end of the shell is provided with an optical fiber cable interface;

the tail end of the optical fiber cable interface is provided with an illumination optical fiber, a signal cable beam combination and a laser-spectrum transmission optical fiber;

The illumination optical fiber and the signal cable are combined, the illumination optical fiber and the signal cable are arranged in the combined beam, and the illumination optical fiber is used for emitting illumination light beams through an illumination optical fiber window; the signal cable is used for receiving the spectrum incident by the common lens and outputting spectrum information to the spectrometer;

The laser-spectrum transmission optical fiber is used for collimating outgoing laser through the optical component and then emitting the outgoing laser through the shared lens.

In a second aspect, the present application provides a fiber optic LIBS system comprising:

The optical fiber cable interface of the miniature probe is respectively connected with the laser and the spectrometer through optical fibers;

and the signal input end of the display unit is connected with the signal cable of the miniature probe.

In a third aspect, the present application provides a method for detecting an optical fiber LIBS system, comprising the steps of:

Step 1, starting an illumination optical fiber, lifting a reflecting plate, extending into a pipeline slit and other scenes to position foreign matters, and observing the surrounding environment of a probe through a display to find the foreign matters;

Step 2, after the foreign matter is positioned, positioning the position to be detected of the foreign matter at the position of the center mark of the picture, and adjusting the focusing distance;

Step 3, after confirming that the error is avoided, adjusting system parameters, clicking a detection button, falling a reflecting mirror, and focusing laser on the surface of the sample to generate laser-induced plasma;

step 4, stopping the laser after the previously set time, collecting and displaying the spectrum in a display screen, and displaying related material information in a corresponding position of the software;

Step 5, lifting the reflecting mirror, and checking the state of the micro ablation pit of the foreign matter at the moment;

and 6, finishing detection, and pulling out the probe and the optical fiber from the detection scene.

Compared with the prior art, the application has the following beneficial effects:

The application adopts a common arrangement mode of camera imaging, laser focusing and targeting and plasma spectrum returning and collecting light paths to solve the problem that optical fiber LIBS equipment cannot penetrate into a narrow pipeline gap of a nuclear power station to detect foreign matters, and performs quantitative element analysis and material identification tracing of the foreign matters. The application realizes the optical fiber LIBS micro probe with the same optical path for laser focusing and spectrum collecting, and realizes the detection flow of the camera aiming target, the lifting of the sensor, the laser targeting and the return spectrum by sharing the optical path and turning over the CMOS sensor.

Drawings

For a clearer description of the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of the structure of the probe of the present application.

FIG. 2 is a cross-sectional view of a probe of the present application.

Fig. 3 is a schematic diagram of the LIBS system of the present application incorporating a probe.

Fig. 4 is a schematic diagram of a practical use scenario of the present application.

The device comprises a lighting optical fiber window 1, a common lens 2, a lighting optical fiber 3, a beam combining of the lighting optical fiber and a signal cable 4, a laser-spectrum transmission optical fiber 5, an optical fiber cable interface 6, a collimating lens 7, a CMOS sensor 8, a laser 9, a digital delay generator 10, a spectrometer 11, a display unit 12, a multimode optical fiber 13, a miniature probe 14, a laser-induced plasma 15 and a sample 16.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

It should be noted that like reference numerals and letters refer to like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the embodiments of the present application, it should be noted that, if the terms "upper," "lower," "horizontal," "inner," and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present application and simplifying the description, and does not indicate or imply that the apparatus or element to be referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

Furthermore, the term "horizontal" if present does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. As "horizontal" merely means that its direction is more horizontal than "vertical", and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the embodiments of the present application, it should also be noted that, unless explicitly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected through an intermediate medium, or communicating between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

The application is described in further detail below with reference to the attached drawing figures:

Referring to fig. 1, an embodiment of the present application discloses a micro probe, which comprises a housing, an optical fiber cable interface 6, an illumination optical fiber and signal cable combination 4, and a laser-spectrum transmission optical fiber 5. The front end of the shell is provided with an illumination optical fiber window 1 and a common lens 2, and the common lens 2 is a focusing lens. The tail end of the shell is provided with an optical fiber cable interface 6, the tail end of the optical fiber cable interface 6 is provided with an illumination optical fiber and signal cable combined beam 4 and a laser-spectrum transmission optical fiber 5, the illumination optical fiber and signal cable combined beam 4 is provided with an illumination optical fiber 3 and a signal cable, the illumination optical fiber 3 is used for emitting illumination light beams through an illumination optical fiber window 1, the signal cable is used for receiving spectrums incident by a common lens 2 and outputting spectrum information to a spectrometer, and the laser-spectrum transmission optical fiber 5 is used for emitting emitted lasers through the common lens 2 after being collimated by an optical component.

The optical assembly includes a collimator lens 7 disposed on the light path of the laser-spectrum transmission fiber 5, and the outgoing laser is focused by the collimator lens 7 onto the surface of the sample 16 to be measured through the common lens 2 to generate a laser-induced plasma 15. The optical path between the optical component and the common lens 2 is also provided with a reversible reflecting mirror, when the reflecting mirror is lifted, the optical fiber or spectrum incident by the common lens 2 can be reflected into the CMOS sensor 8, and the signal output end of the CMOS sensor 8 is connected with a spectrometer or a display unit.

As shown in fig. 3, an embodiment of the present application provides a fiber optic LIBS system comprising a microprobe 14 and a display unit 12. The optical fiber cable interface 6 of the miniature probe is respectively connected with the laser 9 and the spectrometer 11 through optical fibers, and the signal input end of the display unit 12 is connected with the signal cable of the miniature probe. The laser 9, the spectrometer 11 and the display unit 12 are respectively connected with the digital delay generator 10, and the time sequences of the laser 9, the spectrometer 11 and the display unit 12 are controlled by the digital delay generator 10. The optical fiber is a multimode optical fiber 13.

The application has the structural principle that:

As shown in fig. 1-4, the optical fiber cable interface 6 is connected with the illumination optical fiber, the signal cable beam 4 and the laser-spectrum transmission optical fiber 5. The illumination fiber 3 continues to transmit the illumination beam from the illumination fiber 3 to the illumination fiber window 1. When the reversible CMOS sensor 8 falls down, the laser emitted by the laser-spectrum transmission optical fiber 5 is collimated by the collimating lens 7, and then the front-end focusing lens outputs focused laser from the focusing/returning/photographing common lens 2 to break down the surface of the sample 16. In a normal state, the reversible CMOS sensor 8 is kept lifted up, receives a wide-angle image transmitted from the focusing/returning/photographing common lens 2, and outputs the wide-angle image to the screen of the electronic device through the signal wires in the illumination optical fiber and signal cable beam combination 4.

The probe size is 5mm in diameter and 15mm in length. The focusing/returning/photographing shared lens 2, the collimating lens 7 and other optical lenses need to transmit light with the wavelength range of 185nm-1100nm, so that the Nd: YAG laser transmission and full-band spectrum transmission of 1064nm are satisfied. The optical fiber interface in the optical fiber cable interface 6 is an SMA-905 interface, and in order to ensure that the diameter is smaller than 5mm, the optical fiber adopts an armor scheme such as a plastic sheath. The collimating lens 7 should cooperate with the laser-spectrum transmission fiber 5, the focusing/return/camera lens 2, and the focusing lens to achieve a small focusing spot (< 500 microns) of the laser outside the probe 15mm. In addition, the focusing lens and the emergent window should be designed into equivalent wide-angle lenses at the same time so as to meet the imaging requirement of the detection camera.

In real time, the device should determine the focusing distance by the picture transmitted by the camera. A targeting support may also be added in front of the probe to fix the distance between the sample 16 and the probe.

According to the application, a small LIBS probe provided with a camera is designed, which comprises a probe shell, an optical fiber interface, an illumination optical fiber 3, a lens group, a reflecting mirror, a CMOS sensor, a microcontroller, an actuating connector and the like. The laser imaging device is characterized in that the probe is small in size and has a diameter of only 4-6 mm, a CMOS sensor and a camera are arranged, foreign matters to be detected can be imaged and positioned, and when laser targets are shot, a reflecting mirror falls down and the laser focusing and spectrum collecting share an imaging light path of the camera.

When the probe and the optical fiber extend into the scenes such as the slit, the illumination optical fiber 3 is started, and the environment conditions in the slit are transmitted to the CMOS sensor through the camera light path, so that the environment conditions are displayed on the screen, and a user can find the position of the foreign matter conveniently. After the foreign matter is found, aiming and focusing are carried out according to the camera. After the device is ready, a detection button is clicked, the CMOS sensor is lifted, laser passes through the probe to focus on the surface of the foreign matter to generate plasma, and the plasma spectrum is transmitted back to the optical fiber along the same optical path and then transmitted to the spectrometer 11 for analysis. At the end of the test, the CMOS sensor returns to its original position.

The lens of the present application is made of an ultraviolet fused silica material as much as possible.

The flip scheme of the CMOS sensor can also be realized by using mirror flip in the application, so that the precision sensor can be prevented from moving.

The microprobe of the present application is required to be used in conjunction with an optical fiber LIBS system. The 1064nm nanosecond laser pulse generated by the laser 9 enters the specially designed multimode optical fiber 13 through the optical fiber coupling module, and the SMA905 interface at the other end of the multimode optical fiber 13 is connected with the interface of the miniature probe 14, so that the laser pulse is focused on the surface of the sample 16. Because the light path is reversible, the self-luminescence of the laser-induced plasma 15 is recovered by the micro probe 14 along the same light path, and is input into the connected spectrometer 11 through the same multimode optical fiber 13, and then is displayed on the computer screen 12 for spectral analysis and data processing. The timing of all devices is controlled by a digital delay generator 10.

The probe provided by the application works as follows:

(1) Before the probe is used, the inspection optical fiber and the signal wire are connected, the illumination optical fiber 3 emits light normally, the camera images normally when the reflector is lifted, the laser focusing is normal when the reflector falls, and the spectrometer 11 collects signals normally;

(2) The illumination optical fiber 3 is started, the reflecting plate is lifted up, the reflecting plate stretches into scenes such as a pipeline slit and the like to position foreign matters, the surrounding environment of the probe is observed through the display, and the foreign matters are found;

(3) After the foreign matter is positioned, the position to be detected by the foreign matter is positioned at the center mark of the picture, and the focusing distance is adjusted;

(4) After confirming that the error is not found, adjusting system parameters, clicking a detection button, falling a reflecting mirror, and focusing laser on the surface of a sample 16 to generate laser-induced plasma 15;

(5) Stopping the laser after the previously set time, collecting and displaying the spectrum in a display screen, and displaying related material information in a corresponding position of the software;

(6) The reflector is lifted up, and the state of the micro ablation pit of the foreign matter at the moment is checked;

(7) And (5) finishing detection, and pulling out the probe and the optical fiber from a detection scene such as a pipeline slit.

The above is only a preferred embodiment of the present application, and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (8)

1. A miniature probe, comprising:

The front end of the shell is provided with an illumination optical fiber window (1) and a shared lens (2), and the tail end of the shell is provided with an optical fiber cable interface (6);

The optical fiber cable interface (6), the end of the optical fiber cable interface (6) is provided with an illumination optical fiber and signal cable beam combination (4) and a laser-spectrum transmission optical fiber (5);

The system comprises an illumination optical fiber and signal cable combination (4), wherein the illumination optical fiber and signal cable combination (4) is provided with an illumination optical fiber (3) and a signal cable, the illumination optical fiber (3) is used for emitting illumination light beams through an illumination optical fiber window (1), and the signal cable is used for receiving a spectrum incident by a common lens (2) and outputting spectrum information to a spectrometer;

And the laser-spectrum transmission optical fiber (5) is used for collimating outgoing laser through the optical component and then emitting the outgoing laser through the common lens (2).

2. The microprobe according to claim 1, wherein the optical assembly comprises a collimator lens (7) disposed on an exit optical path of the laser-spectrum transmission fiber (5), and the outgoing laser light is focused by the collimator lens (7) onto a surface of the sample (16) to be measured through the common lens (2) to generate the laser-induced plasma (15).

3. The miniature probe according to claim 1, wherein a reflecting mirror capable of turning over is further arranged on an optical path between the optical component and the common lens (2), and when the reflecting mirror is lifted, an optical fiber or spectrum incident by the common lens (2) can be reflected into a CMOS sensor (8), and a signal output end of the CMOS sensor (8) is connected with a spectrometer or a display unit.

4. A microprobe according to claim 1, wherein the common lens (2) is a focusing lens.

5. A fiber optic LIBS system comprising:

the microprobe (14) according to any one of claims 1 to 4, wherein the fiber optic cable interface (6) of the microprobe (14) is connected to the laser (9) and the spectrometer (11) via optical fibers, respectively;

And the signal input end of the display unit (12) is connected with the signal cable of the miniature probe.

6. The fiber optic LIBS system according to claim 5 wherein the laser (9), spectrometer (11) and display unit (12) are each connected to a digital delay generator (10), the timing of the laser (9), spectrometer (11) and display unit (12) being controlled by the digital delay generator (10).

7. The fiber optic LIBS system according to claim 5 wherein the optical fiber is a multimode optical fiber (13).

8. A detection method using the optical fiber LIBS system according to any one of claims 5 to 7 comprising the steps of:

step 1, starting an illumination optical fiber (3), lifting a reflecting plate, extending into a pipeline slit and other scenes to position foreign matters, and observing the surrounding environment of a probe through a display to find the foreign matters;

Step 2, after the foreign matter is positioned, positioning the position to be detected of the foreign matter at the position of the center mark of the picture, and adjusting the focusing distance;

Step 3, after confirming that the error is avoided, adjusting system parameters, clicking a detection button, falling a reflecting mirror, focusing laser on the surface of a sample (16) to generate laser-induced plasma (15);

step 4, stopping the laser after the previously set time, collecting and displaying the spectrum in a display screen, and displaying related material information in a corresponding position of the software;

Step 5, lifting the reflecting mirror, and checking the state of the micro ablation pit of the foreign matter at the moment;

and 6, finishing detection, and pulling out the probe and the optical fiber from the detection scene.