A laser coaxial ion excitation device

Abstract

The present invention discloses a laser coaxial ion excitation device, which includes an optical path center and an ion transmission channel. The optical path center is empty, and the optical path center is coaxial with the ion transmission channel. The ion transmission channel is perpendicular to the matrix carrier. The laser focusing spot is non-uniformly focused. The optical path includes but is not limited to a laser transmission optical path, a visual monitoring optical path, a visual illumination optical path, and an optical intensity monitoring optical path. The structure of the laser coaxial ion excitation device is reasonably arranged, with a wide ion mass range and high resolution, and can effectively improve the ion excitation abundance.

Description

Technical Field:

[0001] The present invention relates to the field of matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis, and more specifically, to a laser coaxial ion excitation device. Background Art:

[0002] The existing matrix-assisted laser desorption ionization time-of-flight mass spectrometry equipment has a complex structure and a relatively large difficulty in laser excitation adjustment. During ion excitation, it is generally offset excitation. The spatial distribution of the excited ion cloud is asymmetric and relatively wide, which is not conducive to the flight of ions after excitation. The ionization efficiency is not ideal, the resolution is not ideal, and the preparation cost is high. The spatially non-uniform distribution, non-uniform ion charge distribution, and non-uniform ion generation time distribution generated by the existing offset excitation optical path are the key factors affecting the mass spectrometry detection results. Summary of the Invention:

[0003] The technical problem to be solved by the present invention is to provide a laser coaxial ion excitation device with a reasonable structural setting, forward excitation, and an adjustable focus symmetric non-uniform light spot.

[0004] The technical solution of the present invention is to provide a laser coaxial ion excitation device, including an optical path center and an ion transmission channel. The optical path center is empty, and the optical path center is coaxial with the ion transmission channel. The ion transmission channel is perpendicular to the matrix carrier. The laser focusing light spot is non-uniformly focused. The optical path includes but is not limited to a laser transmission optical path, a visual monitoring optical path, a visual illumination optical path, and a light intensity monitoring optical path. Among them, the laser transmission optical path includes but is not limited to an objective lens, a total reflection mirror, a folding mirror, a beam expander, and a laser; the visual monitoring optical path includes but is not limited to a laser transmission lens, a light source beam splitter, and a lens group, and the visual monitoring optical path forms a conjugate with the laser; the visual illumination optical path includes but is not limited to a visual light source, a laser transmission lens, and a light source beam splitter, and the visual illumination optical path forms a conjugate with the laser; the light intensity monitoring optical path includes but is not limited to a photosensitive sensor; the ion transmission channel includes but is not limited to a variable-curved surface ion lens, an ion filter screen, and an ion detection device. Among them, the laser is used as the laser light source, and the ion detection device is an existing structure.

[0005] After adopting the above structure, compared with the prior art, the present invention has the following advantages: The present invention has a reasonable structural setting. The excitation optical path performs excitation coaxially along the path of ion generation and ion flight. The spatial state generated by the excitation is symmetrically distributed at the excitation point. The ion cloud generated by laser desorption ionization is uniformly distributed in a space of about 10-200 μm at the excitation point. After focusing, the ion spatial difference is small. After ion flight, the mass spectrometry resolution can be effectively improved.

[0006] Preferably, the objective lens has a hollow structure, and the hollow part serves as the ion transmission channel. The objective lens is arranged perpendicular to the ion matrix carrier.

[0007] Preferably, the total reflection mirror is a hollow structure, the hollow part is an ion transport channel, and the rest is a reflecting mirror.

[0008] Preferably, the folding mirror is a total reflection mirror, which has a central reflecting surface and an annular reflecting surface. The central reflecting surface reflects the central light source to the annular reflecting surface, and the annular reflecting surface reflects the laser coaxially along the incident light, forming an annular laser transmission channel with a hollow center.

[0009] Preferably, the folding mirror has a hole or a fully transparent area in the center. The laser can directly reach the photosensitive sensor through the hole without reflection, so as to monitor or measure the laser intensity.

[0010] Preferably, the wavelength of the visual light source is different from that of the laser, which synchronously monitors the state of the substrate carrier and can also be used to observe the laser excitation focusing adjustment state. The visual light source is a parallel light or a quasi-parallel light source.

[0011] Preferably, the total reflection mirror is a single hollow total reflection mirror for fixed-focus ion excitation or a hollow scanning mirror group for line scanning or area scanning ion excitation. Among them, the hollow scanning mirror group includes one hollow scanning mirror or two hollow scanning mirrors.

[0012] Preferably, a focusing lens group can be added between the beam expander and the folding mirror, but it is not necessary. The focusing lens group can be linked with the visual monitoring device to adjust the focusing position of the laser beam.

[0013] Preferably, the detection surface of the ion detection device is coaxial with the ion transport channel, and the photosensitive sensor is coaxial with the laser.

[0014] Furthermore, the variable-curved surface ion lens is coaxial with the ion output channel, and the variable-curved surface ion lens is a controllable variable-curved surface lens. The controllable variable-curved surface lens can be an electro-controlled variable-curved surface lens, a hydraulic variable-curved surface lens, or a pneumatic variable-curved surface lens, and preferably an electro-controlled variable-curved surface lens. Brief Description of the Drawings:

[0015] Figure 1 This is a schematic diagram of the present invention.

[0016] Figure 2 This is a schematic diagram of the focused energy of the present invention.

[0017] Figure 3 This is a schematic diagram of the ion intensity of the present invention. Detailed Description of the Invention:

[0018] The present invention will be further described below in conjunction with the drawings and specific embodiments:

[0019] As shown in Figures 1-3As shown in the figure, a laser coaxial ion excitation device includes an optical path center and an ion transmission channel. The optical path center is empty and is coaxial with the ion transmission channel. The ion transmission channel is perpendicular to the substrate carrier. The laser focusing spot is non-uniformly focused. The optical path includes but is not limited to a laser transmission optical path, a visual monitoring optical path, a visual illumination optical path, and a light intensity monitoring optical path. Among them, the laser transmission optical path includes but is not limited to an objective lens 10, a total reflection mirror 9, a folding mirror 8, a beam expander 4, and a laser 3. The visual monitoring optical path includes but is not limited to a laser transmission lens 5, a light source beam splitter 6, and a lens group 7. The laser transmission lens 5, the light source beam splitter 6, and the lens group 7 are arranged in sequence. The visual monitoring optical path forms a conjugate with the laser 3 and is monitored through a camera 1. The visual illumination optical path includes but is not limited to a visual light source 2, a laser transmission lens 5, and a light source beam splitter 6. The visual illumination optical path forms a conjugate with the laser 3. The light intensity monitoring optical path includes but is not limited to a photosensitive sensor 12. The ion transmission channel includes but is not limited to an ion filter screen and an ion detection device. Among them, the laser serves as a laser light source, enters the laser transmission optical path, passes through the beam expander 4, the laser transmission lens 5, the folding mirror 8, the total reflection mirror 9 in sequence, and enters the objective lens 10 and the photosensitive sensor 12. The ion detection device is an existing structure and will not be elaborated. Among them, the energy of the laser focusing laser spot is non-uniformly focused from the center to the periphery, and the size of the focusing spot is 10 μm to 500 μm.

[0020] Preferably, the objective lens is a hollow structure, and the hollow part serves as the ion transmission channel. The objective lens is arranged perpendicular to the substrate carrier. Similarly, the total reflection mirror is a hollow structure, the hollow part is the ion transmission channel, and the rest is a reflecting mirror. Further, the folding mirror is a total reflection mirror, which has a central reflecting surface and an annular reflecting surface. The central reflecting surface reflects the central light source to the annular reflecting surface, and the annular reflecting surface reflects the laser coaxially along the incident light, forming an annular laser transmission channel with an empty center. And, the folding mirror has a hole or a fully transparent area in the center, and the laser can directly reach the photosensitive sensor without reflection through the hole, so as to monitor or measure the laser intensity.

[0021] Preferably, the wavelength of the visual light source is different from that of the laser, and the state of the substrate carrier is synchronously monitored, and it can also be used for monitoring the adjustment of laser excitation focusing. The visual light source is a parallel light or a quasi-parallel light source, such as a halogen lamp light source or an LED lamp light source.

[0022] In addition, the total reflection mirror is a single hollow total reflection mirror for fixed-focus ion excitation or a hollow scanning mirror group for line scanning or surface scanning ion excitation. Among them, the hollow scanning mirror group includes one hollow scanning mirror or two hollow scanning mirrors. And, a focusing lens group 13 can be added between the beam expander and the folding mirror, but it is not necessary. The focusing lens group can be linked with the visual monitoring device to adjust the focusing position of the laser beam. Moreover, the detection surface of the ion detection device is coaxial with the ion transmission channel, and the photosensitive sensor is coaxial with the laser.

[0023] Furthermore, the energy of the laser focus laser spot is non-uniformly focused from the center to the periphery, and the size of the focused spot is 10 μm to 500 μm.

[0024] Through the above settings, the coaxial excitation focuses on the spatial distribution of ions: the excitation optical path is excited coaxially along the path of ion generation and ion flight. The spatial state generated by the excitation is symmetrically distributed at the excitation point. The ion cloud generated by laser desorption ionization is uniformly distributed in the space of about 10-200 μm at the excitation point. After focusing, the ion spatial difference is small. After the ions fly, the mass spectrometry resolution can be effectively improved.

[0025] The uniform distribution of non-uniform energy focusing mode improves the excitation efficiency of a wide range of mass-to-charge ratios: when the mass range is small during mass spectrometry detection, the laser energy required for matrix carrier laser ionization and analysis is roughly the same. Uniform excitation energy is required at the excitation point to generate uniformly excited ions. When the mass range is wide during mass spectrometry detection, different laser energies are required to excite ions of different molecular weights, and the excitation needs to be differentiated so that the number of ions excited by large and small molecular weights in the mass range is basically balanced, and the mass range can be extended over a large range. The hollow optical path design forms a non-uniform laser energy distribution at the excitation point. When the laser intensity is constant, by adjusting the energy distribution at the excitation point, it can adapt to the mass range of 100-1,000,000 molecular weights; when the molecular weight range is narrow, such as 1000-3000, or 4000-8000, the focusing mode of Figure 2 2 can be selected, and the excitation efficiency and molecular weight distribution reach equilibrium; when the mass range is large and the mass-to-charge ratio is high, such as 10,000-500,000, Figure 2 The focusing mode of 3 can be selected, the laser energy is relatively concentrated, the number of small molecular weight ions is small, and the number of large molecular weight excitations is large; when the mass range is large and the mass-to-charge ratio is low, 100-100,000, Figure 2 The focusing mode of 1 can be selected, so that the excitation efficiency of lower molecular weights is low and the excitation of higher molecular weights is high; the non-uniformly distributed laser energy at the excitation point can effectively balance the excitation energy required by the molecular weight and the difference in the number of high and low molecular weight excitations in the mass range. The beneficial effects are shown in Figure 3 The dotted line. When the laser distribution at the excitation point is uniform, as the molecular weight increases, the excitation efficiency of the ions shows a downward trend. By adjusting the laser energy at the excitation point, the ion intensity can be made basically flat within the mass range, as shown in Figure 3 The solid line. When the ion abundance curve is basically uniform, the laser intensity or the amplification factor of the ion detector can be increased to meet the sensitivity requirements. At the same time, the requirements of resolution and sensitivity are taken into account.

[0026] Coaxial high-speed dynamic scanning: When a single hollow total reflector is selected, the focal point can be fixed to excite the matrix carrier. When a hollow scanning mirror group is selected, the laser can be scanned and excited along a predetermined trajectory to form linear, planar, and curved scanning modes. After the scanning data is synthesized, a scanning image of points, lines, and planes of the matrix carrier can be formed.

[0027] Real-time monitoring of the excitation or focusing process: Through the coaxial monitoring light source and monitor, the real-time images of the excitation and focusing processes can be observed, and then the required states to be achieved for excitation and focusing can be confirmed.

[0028] Closed-loop monitoring of the excitation energy: At present, after the laser is output, the laser energy cannot be effectively monitored, and it cannot be confirmed whether the excitation is successful or whether the excitation energy and excitation delay can meet the expected requirements. Another benefit of the present invention is that through the photosensitive sensor, it can be monitored whether the energy of each laser pulse has been output as expected during laser excitation, and whether the excitation delay meets the expected use; when monitoring the laser energy, the photosensitive sensor can be but not limited to a photosensitive resistor, a photodiode, etc. corresponding to the laser wavelength. When monitoring the laser excitation delay time, it can be but not limited to a photosensitive triode, an optical fiber photoelectric sensor, etc. corresponding to the laser wavelength.

[0029] Thus, the whole structure is reasonably and simply arranged, with good use effects, a wide ion mass range, high resolution, and can effectively improve the ion excitation abundance.

Claims

1. A laser coaxial ion excitation device, comprising an optical path center and an ion transmission channel, characterized in that: The optical path center is empty and coaxial with the ion transmission channel, which is perpendicular to the matrix carrier. The laser focusing spot is non-uniformly focused. The optical path includes a laser transmission optical path, a visual monitoring optical path, a visual illumination optical path, and a light intensity monitoring optical path; The laser transmission optical path includes an objective lens, a total reflection mirror, a folding mirror, a beam expander, and a laser. The folding mirror is a total reflection mirror with a central reflection surface and an annular reflection surface. The central reflection surface reflects the central light source to the annular reflection surface, and the annular reflection surface reflects the laser coaxially along the incident light to form an annular laser transmission channel with an empty center. Moreover, the folding mirror has a hole or a fully transparent area in the center, and the laser passes through the hole and reaches the photosensitive sensor directly without reflection to monitor or measure the laser intensity; The visual monitoring optical path includes a laser transmission lens, a light source beam splitter, and a lens group. The laser transmission lens, the light source beam splitter, and the lens group are arranged in sequence. The visual monitoring optical path is conjugate with the laser and is monitored by a camera. The visual illumination optical path includes a visual light source, a laser transmission lens, and the light source beam splitter. The visual illumination optical path is conjugate with the laser.

2. The laser coaxial ion excitation device according to claim 1, characterized in that: The light intensity monitoring optical path includes a photosensitive sensor; the ion transmission channel includes a variable-curved surface ion lens, an ion filter screen, or an ion detection device.

3. The laser coaxial ion excitation device according to claim 2, characterized in that: The objective lens has a hollow structure, and the hollow part serves as the ion transmission channel. The objective lens is arranged perpendicular to the matrix carrier.

4. The laser coaxial ion excitation device according to claim 2, characterized in that: The total reflection mirror has a hollow structure, the hollow part is the ion transmission channel, and the rest is the reflection mirror.

5. The laser coaxial ion excitation device according to claim 2, characterized in that: The visual light source has a different wavelength from the laser, synchronously monitors the state of the matrix carrier, and can also be used for laser excitation focusing adjustment.

6. The laser coaxial ion excitation device according to claim 2, characterized in that: The total reflection mirror is a single hollow total reflection mirror for fixed-focus ion excitation or a hollow scanning mirror group for line scanning or area scanning ion excitation. Among them, the hollow scanning mirror group includes one hollow scanning mirror or two hollow scanning mirrors.

7. The laser coaxial ion excitation device according to claim 2, characterized in that: A focusing lens group is added between the beam expander and the folding mirror, and the focusing lens group is linked with the visual monitoring device to adjust the focusing position of the laser beam.

8. The laser coaxial ion excitation device according to claim 1, characterized in that: The energy of the laser focusing laser spot is non-uniformly focused from the center to the periphery, and the size of the focusing spot is 10 μm to 500 μm.

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