CN102297854A - High-efficiency multi-mode laser-induced fluorescence optical path exciting system - Google Patents

Abstract

The present invention provides a high-efficiency multi-mode laser-induced fluorescence optical path excitation system, which includes a laser emitting device, an excited device, a spectroscopic device, a photoelectric conversion device and a signal processing device, and is characterized in that the emitted light beam of the laser emitting device passes through A 1/2 wave plate is arranged on the optical path after collimation, the optical path after the emitted beam is polarized and split, or the splitted optical path after the emitted beam is divided into multiple beams by multiple polarized lights. The excitation system provided by the present invention can make the polarization state of the excitation light consistent with the polarization selectivity direction of the excited system, and can increase the intensity of the excited Raman fluorescence signal by 20% to 50% under the same power. When the original polarization state matches When the resistance is poor, it can be increased by 50% to 80% or even higher.

Description

High-efficiency multi-mode laser-induced fluorescence optical path excitation system

technical field

The invention relates to a fluorescence induction device, in particular to a high-efficiency multi-mode laser-induced fluorescence optical path excitation system. the

Background technique

The laser-induced fluorescence optical path excitation system is mainly used in the fields of protein, DNA and other biological analysis and detection, as well as spectral analysis instruments and equipment for organic chemistry of macromolecular groups. the

As shown in Figure 1, the basic principle and structure of its optical path device are: laser 1 generates laser beams, after passing through optical filter 2, it converges through converging lens 3, and enters the container 5, which is composed of incident window 4 and loaded with excited substances. The excited system composed of the excited substance 6 and the exit window 7, after the excited substance 6 absorbs the laser energy, the energy level transition emits fluorescence or Raman light 8, which passes through the collimating lens group 9, the light splitting element 10, and the imaging lens group 11 The spectroscopic system composed of other parts is used to split the light. The spectrum 12 of different wavelengths is separated according to the spatial position, and focused and imaged on the photoelectric sensor 13. After photoelectric conversion, the obtained electrical signal with a certain signal-to-noise ratio is transmitted to the back-end system for analysis and processing. . the

Among them, the laser 1 refers to the container 5 of the multi-mode laser loaded with the excited substance, which is usually made of transparent quartz, plexiglass, etc., and the material is required to transmit the spectrum of the excited effective fluorescence signal or Raman light signal well. . The photoelectric sensor 13 is a weak light signal sensor, and usually has a photomultiplier tube, a CCD or a photodiode. The excited substance 6 usually includes DNA, protein, macromolecular organic chemical substance or a substance to be detected that can be evenly suspended in the liquid and so on. the

The laser-induced fluorescence device improved in the patent of the present invention usually has the following two types: confocal optical path structure type and orthogonal optical path structure type. The technical characteristics of the confocal structure type are: the direction of the optical axis of the excitation light path and the detection light path are the same. The technical characteristics of the orthogonal structure type are: the laser incident direction is perpendicular to the fluorescence detection direction or forms an angle between 0° and 90°. the

These two types of optical paths are affected by the polarization of the light source and the polarization of the excited system on the excitation efficiency: the laser light emitted by the laser usually has a certain polarization state (polarization direction), while the excited system (especially the macromolecular organic Compound substances, holding containers made of crystal materials) usually have a certain polarization direction selectivity. If the two polarizations are inconsistent, the absorption efficiency of the excited substance will be reduced to varying degrees, and the fluorescence or Raman light signal excited by it will be reduced to a certain extent. The intensity will not reach the maximum stimulating effect. the

The intensity of the excited fluorescence or Raman signal is usually much weaker than that of the excitation light. For example, the intensity of fluorescence is usually only one percent to one ten thousandth of the intensity of the excitation light, and the Raman light is usually only ten thousandth of the intensity of the excitation light. One part to one millionth. Therefore, effectively improving the excitation efficiency and improving the signal-to-noise ratio are the key performance indicators of the laser-induced fluorescence detection system. the

There are usually two optimization methods that try to eliminate this polarization selectivity:

The first is to adjust the linearly polarized light or elliptically polarized light to circularly polarized light by setting a 1/4 wave plate of a specific wavelength, thereby reducing the influence of polarized light on the excited system. Its disadvantage is that it cannot affect the polarization direction selectivity of the excited system 4. The excited system 4 has a good absorption of laser energy conforming to its polarization selection direction, and the absorption efficiency of partial energy with inconsistent polarization directions is still low. the

The second is to accurately measure the polarization direction of the laser beam, and make the polarization selection direction of the excited system consistent with the polarization direction of the laser beam through a precise structural adjustment method. The difficulty of this optimization method is that for multi-mode laser products, the polarization directions of the outgoing beams and the polarization directions of multiple wavelengths of the same laser device are not always consistent; at the same time, for lasers that require In the beam splitting optical path design, the polarizing beam splitter designed and manufactured under the current technical conditions can only accurately split the S light component and the P light component of a specific wavelength among the various wavelengths emitted by the multi-mode laser. This difficulty is especially reflected in the mass production of products. Designers design and manufacture each situation individually to achieve the best situation, which lacks operability. the

Contents of the invention

In view of the above defects, the purpose of the present invention is to provide a high-efficiency multi-mode laser-induced fluorescence optical path excitation system to solve the technical problem of low excitation efficiency of laser-induced fluorescence optical path devices in the prior art. the

To achieve the above object, the present invention adopts the following technical solutions:

A high-efficiency multi-mode laser-induced fluorescence optical path excitation system includes a laser emitting device, an excited device, a spectroscopic device, a photoelectric conversion device, and a signal processing device. On the optical path after the beam emitted by the laser emitting device is collimated, A 1/2 wave plate is arranged on the optical path of the emitted beam after polarized splitting or the splitted optical path after the emitted beam is divided into multiple beams by multiple polarized lights. the

According to the excitation system described in the preferred embodiment of the present invention, the laser emitting device is a multi-mode laser, and the emitted light is filtered by a filter, then passes through a first reflector to change the direction of the optical path, and then passes through a polarizing beam splitter Light splitting, part of the light after splitting is reflected by the second reflector and then enters one side of the excited device, and the other part of the light is emitted from the other side of the excited device after passing through two corresponding third and fourth reflectors In, the two optical paths excite the excited substance in the excited device to emit fluorescence or Raman light, which is focused to the photoelectric conversion device by the spectroscopic device, and the obtained electrical signal is transmitted to the signal processing device. A 1/2 wave plate is arranged between the plate and the second reflection mirror, and between the third and fourth reflection mirrors. the

According to the excitation system described in a preferred embodiment of the present invention, the 1/2 wave plate is used to adjust the polarization mode of the specific wavelength of the excitation beam of the laser emitting device, so that the polarization direction of the beam is consistent with the polarization of the excited device selectivity in the same direction. the

According to the excitation system described in the preferred embodiment of the present invention, the excited device further includes a container provided with a transparent window, and the excited substance is contained in the container. the

According to the excitation system described in the preferred embodiment of the present invention, a converging lens is respectively arranged between the fourth reflecting mirror and the excited device, and between the second reflecting mirror and the excited device. the

According to the excitation system described in the preferred embodiment of the present invention, the spectroscopic device includes a collimating lens group, a grating, and an imaging lens group, and the collimating lens group is arranged in the light emitting direction of the excited device after the light is adjusted by the grating After entering the imaging lens group and focusing, the image is imaged to the photoelectric conversion device. the

According to the excitation system described in a preferred embodiment of the present invention, the 1/2 wave plate is installed on a wave plate installation and adjustment device, and the wave plate installation and adjustment device includes a mounting base, and is installed on the mounting base to be provided with The mounting frame of the runner, the wave plate frame locking ring used to lock the mounting frame and the wave plate pressure ring, the 1/2 wave plate is arranged on the mounting plate through the wave plate pressure ring and several washers on the shelf. the

Owing to adopting above technical characterictic, make the present invention compare with prior art, have following advantage and positive effect:

In the optical path of the multi-mode laser, any position on the optical path after collimation in the case of excitation of a single beam, any position on the optical path after splitting of the laser beam through a polarization beam splitter, or For any position on the optical path after the laser beam is divided into multiple beams through multiple polarization beam splitters, several 1/2 wave plates are set to adjust the polarization mode of the specific wavelength of the excitation beam (see Figure 5), Therefore, the polarization state of the excitation light is consistent with the polarization selectivity direction of the excited system, and the intensity of the excited Raman fluorescence signal can be increased by 20% to 50% under the same power. When the original polarization state matching is poor, it can Increase by 50% to 80% or even higher. the

Description of drawings

Figure 1 is a schematic diagram of the basic principle of the laser-induced fluorescence device;

Figure 2 is a schematic diagram of 1/2 wave plate polarization;

Figure 3 is an exploded view of the wave plate installation and adjustment device provided by the present invention;

Fig. 4 is a structure diagram of an embodiment of the present invention. the

Detailed ways

Several preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any alternatives, modifications, equivalent methods and schemes made on the spirit and scope of the present invention. In order to provide the public with a thorough understanding of the present invention, specific details are set forth in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details. the

The core idea of the present invention is: by setting a suitable wave plate device (one or more plates) at a suitable position in the optical path of the multi-mode laser to adjust the polarization mode of the specific wavelength of the excitation beam, so that the polarization of the excitation light The polarization selectivity direction of the state and the excited system is consistent, and the intensity of the excited Raman fluorescence signal can be increased by 20% to 50% at the same power. When the original polarization state matching is poor, it can be increased by 50% to 80%. or even higher. the

For the case of single-beam excitation, set it at any position on the optical path after collimation; for the case where the laser beam passes through the polarization beam splitter, set the polarization beam splitter at any position on the optical path after the split; When the polarizing beam splitter is divided into multiple beams of light, the polarizing beam splitter is arranged at any position on the optical path after the splitting. the

As shown in FIG. 2 , the basic principle of deflecting the vibration direction by the 1/2 wave plate 37 is the basic principle of optics, and will not be repeated here. The basic concept is briefly described as follows: the incident light is monochromatic light, and its polarization component is determined by the S component (vibration direction as shown in Figure 4) and the P component (vibration direction as shown in Figure 4). When there is only the S component or only the P component, it is called a line polarized light. The beam containing S component and P component is elliptically polarized light. The function of the bisection-to-one wave plate is to change the polarization direction by 90 degrees, that is, the vibration direction of the outgoing light and the vibration direction of the incident light are different by 90 degrees as shown in the figure. the

As shown in Figure 3, the 1/2 wave plate in the present invention is usually fixed in position by the following wave plate installation and adjustment device. The wave plate installation and adjustment device mentioned in the present invention includes a wave plate pressure ring 38, a rubber washer 39, two 1, 2 wave plates 40, a washer 41, a wave plate mounting frame 42, a wave plate mounting seat 43, a wave plate frame lock Ring 44, lock screw 46, lock screw 50 and other parts. the

Among them, the function of the wave plate pressure ring 38 is to fasten the wave plate on the wave plate mounting frame evenly under force, and the connection relationship between the wave plate pressure ring and the wave plate mounting frame is fastened with fine threads. Thread glue can be applied. The wave plate mounting frame 42 is installed in the round hole of the wave plate mounting seat as shown in the figure, the fit tolerance is +0.01-+0.05mm, it can rotate freely, but the amount of shaking is small. The installation height of the wave plate installation seat 43 is determined by the height of the actual system optical axis from the installation surface. The function of the rotating wheel 48 of the wave plate mounting frame 42 is to accurately rotate the angle of the wave plate manually or with other tooling, so as to obtain the best effect mentioned above. The function of the locking screw 46 is to fasten the locking ring 44 of the wave plate mounting frame and the wave plate mounting frame 42 together through the screw hole 49 after the debugging is completed, so as to reduce the position and angle changes of the wave plate caused by vibration. The function of the locking screw 50 is to make the wave plate mounting frame 43 and the wave plate mounting frame 42 tightly locked and installed in the screw hole position 45 . the

Generally speaking, the angle sensitivity of the optical path to the wave plate is generally about 1-3°. This structure adopts the wave plate mounting frame 42 with a large roller (the diameter of the wheel is twice the diameter of the wave plate). For example, if the diameter of the wave plate is 12mm, then the diameter of the roller is more than 24mm, and the adjustment amount is 0.5mm to 1.5mm. This precision can be achieved by spinning the wheel with bare hands, by virtue of the perception of the hand. Also can design such adjusting stick 47, process a circular hole every 30 degrees on the roller (see the holes arranged on 48, the diameter 2mm of the hole, depth 5mm, totally 12), during adjustment, the stick tooling 47 Insert one end into a hole, hold the other end, and adjust the angle of the wave plate through the handle. The small stick tooling 47 can be designed at about 50 mm to 100 mm. At this time, the adjusted angular positioning range can reach 1.7 mm to 5.1 mm, and the angular positioning accuracy that can be achieved is more than 2 to 4 times higher than the above method. the

Please refer to FIG. 4 , which discusses a schematic diagram of a specific embodiment of the present invention, which includes a laser 51. After passing through an optical filter 52, the direction of the light path is changed through a reflector 53, and after passing through a polarization splitter 54, it is changed through reflectors 55, 56, and 57. In the direction of the light path, through the converging lenses 58 and 59 with the same focal length and relative aperture, it enters the excited device consisting of the container 60 containing the excited substance and the excited substance 61. The excited substance 61 absorbs part of the laser energy and emits fluorescence or The Raman light 62 is usually designed with a transparent window 63 on the container 60 loaded with the excited substance, passes through a spectroscopic device including a collimating lens group 64, a spectroscopic element such as a grating 65 and an imaging lens group 66, and is focused and imaged onto a photoelectric sensor 67, thereby The electrical signal with a certain signal-to-noise ratio is transmitted to the signal processing device 66 for analysis and processing. the

The laser 51 mentioned in this example refers to a multi-mode laser. The container 60 containing the excited substance 61 is usually made of transparent quartz, plexiglass, etc., and the material is required to transmit the spectrum of the excited effective fluorescence signal or Raman light signal well. The photoelectric sensor 67 is a weak light signal sensor, and usually has a photomultiplier tube, a CCD or a photodiode. Excited substances 61 usually include DNA, proteins, macromolecular organic chemical substances or substances to be detected that can be uniformly suspended in liquid, etc. In this example, the purpose of using dual optical paths with opposite incidence is to make the excitation effect at both ends uniform. Because the length of the container 60 in the direction of the optical axis 69 is relatively large, when the light energy of a single light path penetrates the material, the energy will gradually decrease, and the excitation effect on the other section will be significantly reduced. the stimulating effect. At the same time, it is known that the detected system has polarization selectivity (that is, the container containing the detected substance or the detected substance has certain polarization selectivity). There are two kinds of Raman light-labeled dyes for the detected substances, which are 6-FAM (maximum absorption wavelength 494nm, maximum emission wavelength 518nm) and HEX (maximum absorption wavelength 533nm, maximum emission wavelength 559nm) of TaKaRa Company in Japan. the

The laser is an argon ion gas laser. The laser power is 50mW, and the beam diameter is 1mm. It contains 6 main spectral lines of 458nm, 476nm, 488nm, 497nm, 502nm, and 514.5nm. The energy of the 488nm and 514.5nm spectral lines accounts for more than 80% of the total energy. The 514.5nm energy ratio is about 2:1. the

In the method involved in the patent of the present invention, two identical 1/2 wave plates 70 and 71 are placed in the optical path device through the adjustment installation device shown in FIG. 3 . the

The reasons for placing this position are: (1) The number of optical components and optical performance parameters at both ends of the excited substance are exactly the same, and the state of the wave plate is exactly the same at this position, and the position is spatially interchangeable; (2) The position of the The optical path is long, which is suitable for setting the wave plate structure on the structure, leaving room for the debugging of the wave plate. the

The laser power is 50mW. After splitting, the maximum energy density on the surface of each wave plate is 50000w/m ² . It is advisable to use titanium dioxide (TiO ₂ ), a coating material that can withstand high radiation energy, as the anti-reflection coating material (the material can withstand energy The density is as high as 2x10 ⁶ w/m ² or more, the data is available for public consultation), and it is suitable for long-term work.

For the 1/2 wave plate mentioned in the method involved in the patent of the present invention, if the system gives priority to the Raman light emitted by the 6-FAM dye, the 1/2 wave plate at the wavelength position of 488nm can be designed; if the system gives priority to the HEX dye For the emitted Raman light, a 1/2 wave plate at the wavelength position of 514.5nm can be designed. If two dyes are to be balanced, the wavelength of the 1/2 wave plate should be between 488nm and 514.5nm. the

Its efficiency can be calculated as shown in Table 1. the

Table 1

The X11, X12, X21, and X22 data in the above table are experimental measurement data. It is only used as an example to illustrate the method and is for reference only. Substituting into the formulas (2), (3) and (4) in Article 2 of the content of the invention, the value of the characteristic wavelength λ that can be calculated is 501.25nm, which is the wavelength design value of the 1/2 wave plate. the

The preferred embodiments of the invention are provided only to help illustrate the invention. The preferred embodiments are not exhaustive in all detail, nor are the inventions limited to specific embodiments described. Obviously, many modifications and variations can be made based on the contents of this specification. This description selects and specifically describes these embodiments in order to better explain the principle and practical application of the present invention, so that those skilled in the art can make good use of the present invention. The invention is to be limited only by the claims, along with their full scope and equivalents. the

Claims (7)

1. A high-efficiency multimodal laser-induced fluorescence optical path excitation system, comprising a laser emitting device, an excited device, a spectroscopic device, a photoelectric conversion device and a signal processing device, is characterized in that the beam emitted by the laser emitting device is collimated A 1/2 wave plate is arranged on the direct optical path, the optical path of the emitted beam after polarized splitting, or the splitted optical path after the emitted beam is divided into multiple beams by multiple polarized lights. 2. The excitation system as claimed in claim 1, wherein the laser emitting device is a multi-mode laser, and after the emitted light is filtered by a filter, the direction of the light path is changed by a first reflector and then passed by a The polarizing beam splitter splits the light, and part of the light after the split is reflected by the second reflector and then enters one side of the excited device, and the other part of the light passes through two corresponding third and fourth reflectors and passes through the other side of the excited device. One side is injected, and the two optical paths excite the excited substance in the excited device to emit fluorescence or Raman light, which is focused to the photoelectric conversion device by the spectroscopic device, and the electrical signal is transmitted to the signal processing device. A 1/2 wave plate is arranged between the polarization beam splitter and the second reflector, and between the third and fourth reflectors. 3. The excitation system according to claim 1, wherein the 1/2 wave plate is used to adjust the polarization mode of the specific wavelength of the excitation beam of the laser emitting device, so that the polarization direction of the beam is consistent with the excited The polarization selectivity direction of the device is consistent. 4. The excitation system according to claim 1, wherein the excited device further comprises a container provided with a transparent window, and the excited substance is contained in the container. 5. The exciting system according to claim 1, wherein a converging mirror is arranged between the fourth reflecting mirror and the excited device, and between the second reflecting mirror and the excited device. lens. 6. The excitation system according to claim 1, wherein the spectroscopic device comprises a collimator lens group, a grating, and an imaging lens group, and the collimator lens group is arranged in the light exit direction of the excited device through the grating The adjusted light enters the imaging lens group to be focused and then imaged to the photoelectric conversion device. 7. The excitation system according to claim 1, wherein the 1/2 wave plate is installed on a wave plate installation and adjustment device, and the wave plate installation and adjustment device includes a mounting seat, and is installed on the mounting seat A mounting frame with a runner, a wave plate frame locking ring for locking the mounting frame and a wave plate pressure ring are arranged on the top, and the 1/2 wave plate is arranged on the wave plate through the wave plate pressure ring and several washers. on the mounting bracket.

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