CN215525538U - LIBS backscattering collection target detection device - Google Patents
LIBS backscattering collection target detection device Download PDFInfo
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- CN215525538U CN215525538U CN202121472554.3U CN202121472554U CN215525538U CN 215525538 U CN215525538 U CN 215525538U CN 202121472554 U CN202121472554 U CN 202121472554U CN 215525538 U CN215525538 U CN 215525538U
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Abstract
The utility model discloses a LIBS back scattering collection target detection device, which comprises a laser and a spectroscope, wherein a light beam vertically bombards the surface of a target substance after being reflected by a plurality of reflectors and focused by a lens; the other beam passes through the light path adjusting device and then is focused by the lens to bombard the surface of the target substance, so that the two beams have optical path difference, and the incidence directions of the two beams bombarding the target substance are orthogonal; a scattering spectrum collecting means is provided in a range of scattering light of a plasma cloud generated on the surface of the target substance. By designing an orthogonal double-pulse femtosecond laser LIBS optical path diagram, the optical path difference of two optical paths is controlled, so that the spectral intensity generated by breakdown and ablation of the target is greatly improved. By arranging the collecting lens behind the high-reflection mirror M10, which is equivalent to arranging a telescope with a back view, the incident light which influences the collected spectrum is reflected by the M10, and simultaneously, the spectrum of the plasma plume can be collected as much as possible.
Description
Technical Field
The utility model relates to a monitoring device for a LIBS backscattering collection mode, in particular to a LIBS backscattering collection target detection device.
Background
The Laser Induced Breakdown Spectroscopy (LIBS) technology for measuring trace elements and nondestructive inspection is one of the current detection means, and the femtosecond pulse laser is focused to achieve extremely high power density, so that target substances (gas, liquid and solid) are further bombarded, the detection limit is reached, and the target substances are qualitatively and quantitatively analyzed.
In the prior art, the collection efficiency of scattered light of a plasma plume generated by LIBS is generally low, so that the spectral resolution is low, and therefore, a characteristic peak with weak intensity cannot be accurately distinguished, and some useful information is missed. Meanwhile, when the scattering spectrum is collected at the side face, the incident light with strong light intensity is collected at the same time, so that certain influence is generated on spectrum resolution.
Disclosure of Invention
Aiming at the defects of the prior art, the technical problems to be solved by the utility model are as follows: the spectrum intensity and the spectrum collection efficiency are improved, and the influence of incident light on the collected spectrum is reduced.
In order to solve the technical problems, the utility model adopts the following technical scheme:
a LIBS backscattering collection target detection device comprises a laser and a spectroscope BS2, wherein laser emitted by the laser can be divided into a first light beam and a second light beam through the spectroscope BS2, the first light beam is reflected through a plurality of reflectors (M1-M2, M10) and is focused through a lens R1 and then vertically bombards the surface of a target substance; the second light beam is reflected by a plurality of reflecting mirrors (M3-M9), focused by a lens R2 and then bombarded on the surface of the target substance, the optical path difference is formed between the first light beam and the second light beam, and the incidence directions of the first light beam and the second light beam for bombarding the target substance are orthogonal; a scattering spectrum collecting means is provided in a range of scattering light of a plasma cloud generated on the surface of the target substance.
Further, the collection device of the scattering spectrum comprises a collection lens R3 arranged on the side of the lens R1, which is far away from the target substance, and a collection optical fiber is arranged at the focus of the side of the collection lens R3, which is far away from the target substance, and the other end of the collection optical fiber is connected with an ICCD spectrometer which is connected with a computer.
Further, the focal length f =100mm of the lens R1 and the lens R2, and the diameter of the collecting lens R3 is larger than that of the lens R1 and the lens R2, and the focal length f =60 mm.
Further, a reflecting mirror M10 is provided between the lens R1 and the collecting lens R3, and a reflecting surface of the reflecting mirror M10 faces the lens R1.
Further, the reflector M10 is a coated high-reflectivity mirror.
Further, a spectroscope BS1 is arranged between the laser and the spectroscope BS2, and a power meter is arranged on the back side of the spectroscope BS 1.
Further, the splitting ratio of the splitting mirror BS1 is 90:10, and the splitting ratio of the splitting mirror BS2 is 50: 50.
Further, a diaphragm L1 is arranged between the spectroscope BS1 and the laser.
Furthermore, the optical element further comprises a plurality of stepping motors which are respectively arranged on the optical elements.
Furthermore, an attenuation sheet is arranged on the optical path of the first light beam and/or the second light beam.
Compared with the prior art, the utility model has the beneficial effects that:
1. the LIBS orthogonal double-optical-path design enables the spectral intensity to be improved by one order of magnitude compared with the single-pulse laser breakdown spectral intensity, two beams of pulse laser form an optical path difference through the orthogonal double-optical-path design, so that one beam of laser vertically reaches the surface of a target material to form a plasma cloud, the other beam of pulse laser is parallel to the surface of the target material to be shot into the plasma cloud, the plasma cloud is focused, the spectral intensity is improved, and the spectrum can penetrate through the plasma cloud cluster as much as possible to reach a collecting lens to be analyzed by a spectrometer.
2. A collecting lens with a larger diameter is erected right behind the incident light reflector, so that the spectrum is collected as much as possible within the divergence angle range of 2 pi of the plasma plume, and the collection efficiency of the spectrum is improved.
3. Since the scattered light is mixed with the reflected light component photons of the incident light and the photons pass through the high reflecting mirror M10 together, most of the incident light wavelength photons are reflected by the high reflecting mirror M10, and only the photons with inconsistent spectra are focused to the collecting optical fiber through the high reflecting mirror M10 by the following collecting lens so as to be analyzed by the ICCD spectrometer, so that the influence of the incident light on the collecting spectrum is reduced.
Drawings
FIG. 1 is a schematic structural view of the present invention;
in the figure: 1 laser, 2 power meter, 3 collection fiber, 4-ICCD spectrometer, 5 computer.
Detailed Description
The utility model is further illustrated with reference to the following figures and examples.
Example (b):
as shown in fig. 1, a LIBS backscatter collection target detection device includes a laser 1, and further includes a beam splitter BS2, laser light emitted by the laser 1 can be split into a first beam and a second beam by a beam splitter BS2, the first beam is reflected by a plurality of mirrors (M1-M2, M10) and focused by a lens R1 to vertically bombard a surface of a target substance; the second light beam is reflected by a plurality of reflecting mirrors (M3-M9), focused by a lens R2 and then bombarded on the surface of the target substance, the optical path difference is formed between the first light beam and the second light beam, and the incidence directions of the first light beam and the second light beam for bombarding the target substance are orthogonal; a scattering spectrum collecting means is provided in a range of scattering light of a plasma cloud generated on the surface of the target substance. A spectroscope BS1 is arranged between the laser 1 and the spectroscope BS2, and a power meter 2 is arranged on the back side of the spectroscope BS 1. The splitting ratio of the beam splitter BS1 is 90:10, and the splitting ratio of the beam splitter BS2 is 50: 50. A diaphragm L1 is arranged between the beam splitter BS1 and the laser 1.
The scattering spectrum collecting device comprises a collecting lens R3 arranged on the side, away from the target substance, of the lens R1, a collecting optical fiber 3 is arranged at the focus of the side, away from the target substance, of the collecting lens R3, the other end of the collecting optical fiber 3 is connected with an ICCD spectrometer 4, and the ICCD spectrometer 4 is connected with a computer 5. The focal length f =100mm of the lens R1 and the lens R2, and the diameter of the collecting lens R3 is larger than that of the lens R1 and the lens R2, and the focal length f =60 mm. A reflecting mirror M10 is arranged between the lens R1 and the collecting lens R3, and the reflecting surface of the reflecting mirror M10 is opposite to the lens R1. The reflector M10 is a coated high-reflectivity mirror.
The optical element is characterized by further comprising a plurality of stepping motors, wherein the stepping motors are respectively arranged on the optical elements. And an attenuation sheet is arranged on the optical path of the first light beam and/or the second light beam.
The utility model improves the spectral intensity by one order of magnitude compared with the single pulse laser breakdown spectral intensity through the LIBS orthogonal double-light-path design, two beams of pulse lasers form an optical path difference through the orthogonal double-light-path design, so that one beam of laser vertically reaches the surface of a target material to form a plasma cloud, the other beam of pulse laser is parallel to the surface of the target material to be emitted into the plasma cloud, and the plasma cloud is focused to ensure that the spectrum can penetrate through the plasma cloud cluster as much as possible to reach a collecting lens and be analyzed by a spectrometer;
as shown in FIG. 1, a collecting lens with a larger diameter is arranged right behind the incident light reflector, so that the spectrum is collected as much as possible within the divergence angle range of 2 π of the plasma plume, and meanwhile, when the reflected light component photons of the incident light are mixed with the scattered light and pass through the high reflector, most of the incident light wavelength photons are reflected by the high reflector, and only the photons not in accordance with the spectrum are focused to the collecting fiber 3 by the following collecting lens through the high reflector, so that we can analyze and discuss the photons by the spectrometer. The device can greatly improve the intensity of the collected spectrum, thereby being capable of analyzing and discussing the trace atomic molecular spectrum.
In use, the femtosecond pulse laser 1 emits a beam spot diameter 100mm, power 102mW, center wavelength 102nm, frequency 103Hz, pulse width 101fs near infrared femtosecond pulse laser, beam limiting is carried out on a light beam through a diaphragm S1, a beam of parallel light is obtained through shaping, the beam of parallel light is reflected to M2 on a displacement platform through a plane mirror M1 and reaches a spectroscope BS1 for light splitting, two beams of pulse light pass through different optical paths on the displacement platform, the first beam of pulse light is vertically incident to the surface of a target, the first beam of pulse light is focused to the position of the surface of the target through a lens R1, and the target is ablatedAnd generating a high-temperature high-density plasma cloud, adjusting the optical path of the other pulse beam by the displacement platform, and enabling the pulse which is later than the vertical incidence to reach the plasma cloud generated by the former beam in a direction parallel to the surface of the target material so as to generate a double-pulse enhanced spectrum.
The working principle is shown in the figure, the laser induced excitation spectrum of the target is obtained through the light path design, the target atom or ion species and relative content are obtained through the spectral peak position corresponding to the spectral wavelength (NIST database), and the method has the advantage that multi-element simultaneous measurement can be carried out.
In the LIBS spectrum collection process, the molecular spectrum and the atomic ion spectrum are collected by the ICCD spectrometer 4 together, when the spectrum analysis is carried out, the molecular spectrum and the background which are biased to the continuous spectrum need to be removed, the atomic and ion spectrum information is analyzed and discussed separately, and the molecular spectrum occupies the dominant position in the high-frequency band and mainly analyzes the spectrum information of the band larger than 400 nm.
The device ensures the stability of the output power of the pulse laser through the observation of the power meter 2, and ensures the smooth operation of the subsequent experiment.
The pulse intensity is continuously adjusted through the attenuation sheet, so that the intensity between the two pulse lasers is periodically changed, and the influence of different pulse phase differences and pulse intensity changes on the spectral enhancement of the plasma is discussed.
The device excites atoms of several target sample atoms and ions with different valence states by using a Laser Induced Breakdown Spectroscopy (LIBS) method, and reversely deduces the composition of the target sample; and calculating the target material content through the peak area ratio of the excitation characteristic spectrum peak, thereby qualitatively and quantitatively calibrating the content of different substances in the target material.
The influence and contribution of different target material contents on the whole detection sample can be further obtained through LIBS spectrum experimental data, an ordered target material molecule screening mode is obtained through measuring LIBS spectrum characteristics, and the target material can be rapidly detected in a nondestructive mode and multiple elements.
Biological detection agents with different contents are discussed through further analysis, because LIBS experiments can generate laser-induced breakdown spectra, people can distinguish the interior of a cup of the biological detection agent through atomic or molecular spectral characteristic peaks, and further discuss the content of the biological detection agent through the peak area ratio of the characteristic spectrum, and meanwhile, a group of calibrated standard substances can be used for quantitative discussion, because the LIBS detection technology has the advantages of real-time, nondestructive, long-distance and multi-element simultaneous measurement,
the device bright spot can accurately control two bundles of femtosecond laser pulses to successively reach a time difference value through the stepping motor, and further can accurately control two bundles of pulses through adjusting the stepping motor so that a double-pulse laser induced breakdown spectroscopy (DP-LIBS) excitation spectrum can be promoted by one to two orders of magnitude, thereby greatly improving the detection limit, easily distinguishing a few weak atomic or molecular spectrums, providing a scientific detection method for detecting trace or even trace biological detection targets, and greatly improving the detection capability and detection efficiency.
The method can further measure the types and contents of multiple elements and multiple molecules in a complex organism by using a similar experimental method, provides reliable technical support for simultaneous quantitative analysis of the multiple elements, greatly improves the detection limit, provides reliable support for obtaining new atom or molecule measurement and new test data for quantitative analysis, greatly simplifies a new detection mode, obviously improves the resolution of a detection result, lays a foundation for innovation of the new detection mode, and is also carried out in a coaxial double-pulse light beam enhancement and double-pulse orthogonal post-step enhancement mode. Further, LIBS orthogonal double-pulse spectrum enhancement technology is utilized to carry out species and content quantitative resolution on the biological detection object, so that multispectral simultaneous detection can be rapidly, accurately and visually carried out in an actual combat environment, and a complete multispectral spectrogram with clear resolution can be obtained.
Laser Induced Breakdown Spectroscopy (LIBS) technology basic working principle: the laser generates a beam of ultra-strong light (10)14-16W/cm2) Ultra-short (fs magnitude) pulse laser is focused through a lens to generate self-focusing and self-defocusing effects to form a light filament, the light filament is focused on a target surface to be measured to form a high-temperature high-density plasma cloud, and a plasma plume is erected on the position of the high-temperature high-density plasma cloudThe plasma spectrum is collected by a large-area lens, the spectrum is guided into an enhanced charge coupled device (Intensified CCD) -ICCD through an optical fiber at the back of the lens, and the collected spectrum is subjected to time-space change analysis. The type and the content of each target material are qualitatively and quantitatively given on the basis of the time-space change analysis, and corresponding atom or molecular structure characteristic spectrum information is further obtained, so that a specific biological sample to be detected can be reversely calibrated. Particular emphasis is here given to: a group of standard substances of the object to be detected needs to be determined, and calibration needs to be carried out at the moment.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the technical solutions, and although the present invention has been described in detail by referring to the preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention can be made without departing from the spirit and scope of the technical solutions, and all the modifications and equivalent substitutions should be covered by the claims of the present invention.
Claims (10)
1. A LIBS backscattering collection target detection device comprises a laser and a scattering spectrum collection device, wherein the laser can emit laser to bombard the surface of a target to generate a plasma cloud, and scattered light generated by the plasma cloud can be collected and analyzed by the scattering spectrum collection device; the laser device is characterized by further comprising a beam splitter BS2, wherein laser emitted by the laser device can be divided into a first light beam and a second light beam through the beam splitter BS2, the first light beam is reflected through a plurality of reflecting mirrors and is focused through a lens R1 to vertically bombard the surface of a target substance; the second light beam passes through the light path adjusting device, is focused by the lens R2 and then bombards the surface of the target substance, so that the first light beam and the second light beam have optical path difference, and the incidence directions of the first light beam and the second light beam for bombarding the target substance are orthogonal.
2. The LIBS backscatter collection target detection device of claim 1, wherein the collection device comprises a collection lens R3 disposed on a side of the lens R1 facing away from the target material, and a collection fiber is disposed at a focal point of the collection lens R3 facing away from the target material, and the other end of the collection fiber is connected to an ICCD spectrometer, and the ICCD spectrometer is connected to a computer.
3. The LIBS backscatter collection target detection apparatus of claim 2, wherein the focal length f =100mm for the lens R1 and the lens R2, and the diameter of the collection lens R3 is larger than that of the lens R1 and the lens R2, and the focal length f =60 mm.
4. The LIBS backscatter collecting target detection apparatus of claim 3, wherein a mirror M10 is disposed between the lens R1 and the collecting lens R3, and a reflective surface of the mirror M10 faces the lens R1.
5. The LIBS backscatter collecting target detection device of claim 4, wherein the mirror M10 is a coated high-reflectivity mirror.
6. The LIBS backscatter collecting target detection device of any one of claims 1-5, wherein a spectroscope BS1 is further provided between the laser and spectroscope BS2, and a power meter is provided on the back side of spectroscope BS 1.
7. The LIBS backscatter collection target detection device of claim 6, wherein the splitting ratio of the beam splitter BS1 is 90:10 and the splitting ratio of the beam splitter BS2 is 50: 50.
8. The LIBS backscatter collection target detection device of claim 6, wherein a stop L1 is disposed between the beam splitter BS1 and the laser.
9. The LIBS backscatter collection target detection apparatus of claim 6, further comprising a plurality of stepper motors, the stepper motors being respectively disposed on the optical elements.
10. The LIBS backscatter collection target detection device of claim 6, wherein an attenuation plate is further disposed in the optical path of the first beam and/or the second beam.
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