Transmission laser spectrum test device based on single swept frequency light source

Abstract

The invention discloses a transmission-type laser spectrum testing device based on a single frequency-sweeping light source. The frequency-sweeping laser light source is divided into two laser beams by an optical fiber beam splitter. One laser beam is a frequency-doubled light of a fundamental frequency light, which is used to detect a Raman scattering signal. The other laser beam is a frequency-quadrupled light of the fundamental frequency light, which is used to detect a fluorescence signal by laser induction. The detection of LIF and RS is realized simultaneously by using a frequency-sweeping laser light source. The synchronous measurement of the Raman signal and the fluorescence signal can be realized by using a Raman single-photon detector, an adjustable narrow-band filter and a fluorescence detector, without using an expensive grating spectrometer and a planar array / linear array detector, thereby greatly reducing the volume and cost of the testing device of the invention and facilitating the miniaturization of the testing device.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectric detection, and in particular relates to a transmission-type laser spectrum testing device based on a single frequency-sweeping light source. Background Art

[0002] Laser spectroscopy has been widely used in the field of drug testing due to its characteristics of no sample pretreatment, fast and non-destructive. Common laser spectroscopy methods include laser Raman spectroscopy (RS) analysis and laser induced fluorescence spectroscopy (LIF). Among them, laser Raman spectroscopy is an analysis method that analyzes the scattered spectra of different incident light frequencies to obtain molecular vibration and rotation information, and is applied to molecular structure research. It is a "fingerprint" spectrum that can characterize molecular structure information. When a high-energy excitation laser is irradiated onto a sample, part of the laser is absorbed and re-radiated, and the frequency and intensity will change due to molecular vibration in the process. By measuring the scattered signal generated by this deviation from the initial frequency or intensity, the chemical substances present in the sample and their structural information can be identified. Due to the advantages of non-contact measurement, fast detection speed, no sample preparation, high sensitivity and resolution, it can quickly identify drugs hidden in various powders and solutions. Laser induced fluorescence spectroscopy is an optical spectroscopy method that uses a high-energy excitation laser beam to irradiate the sample to produce a fluorescence signal within a specific wavelength range. These fluorescence signals are related to the chemical substances present in the sample, and the substances present in the sample and their concentrations can be identified by measuring parameters such as their intensity, emission wavelength and lifetime.

[0003] With the emergence of new drugs and hazardous chemicals, their composition and structure are constantly changing, and the drugs actually seized are complex in composition, low in content, and adulterants usually contain highly fluorescent substances. The detection of drugs and hazardous chemicals is highly dependent on universal substrates and standard spectral libraries. If only a single spectrum is used, it is easy to miss the detection if the spectrum matching fails.

[0004] Therefore, it is urgent to optimize the existing spectral technology in response to the new development of drugs and hazardous chemicals, and to develop fast and accurate qualitative and quantitative analysis devices for drugs and hazardous chemicals. At present, the common method for obtaining Raman spectra and laser-induced fluorescence spectra is to use two fixed-wavelength laser light sources and use grating spectrum splitting modules and linear / area array detection modules for detection. This method greatly increases the size and cost of the instrument. On the other hand, traditional Raman and fluorescence spectra mostly use reflective detection methods, which have the problem of weak Raman and fluorescence signals, limiting their application in the field of on-site detection. Summary of the invention

[0005] The purpose of the present invention is to provide a transmission laser spectroscopy testing device based on a single swept-frequency light source, which can simultaneously detect LIF and RS by using one laser light source, effectively reduce system cost and realize system miniaturization, while obtaining high-quality fluorescence signals and Raman signals.

[0006] The technical solution of the present invention is a transmission-type laser spectrum test device based on a single swept-frequency light source, comprising a laser source, a laser light source control module, an optical fiber beam splitter, a sample to be tested, a collection device, and a host computer; the laser source is a swept-frequency laser light source; the collection device comprises a Raman single-photon detector and a fluorescence detector;

[0007] The frequency sweeping laser light source is connected to the optical fiber beam splitter through the main output optical fiber, the optical fiber beam splitter is connected to the double frequency module through the first splitting optical fiber, and is connected to the quadruple frequency module through the second splitting optical fiber; a first collimating lens and a first focusing mirror are sequentially arranged at the front end of the double frequency module; a second collimating lens and a second focusing mirror are sequentially arranged at the front end of the quadruple frequency module;

[0008] The host computer is connected to the Raman single-photon detector through a first signal transmission line, and is connected to the fluorescence detector through a second signal transmission line; a third focusing mirror, a bandpass filter and a long-wave pass filter are sequentially arranged at the front end of the Raman single-photon detector; a fourth focusing mirror and an adjustable narrow-band filter are sequentially arranged at the front end of the fluorescence detector;

[0009] A closed-loop optical path for detecting Raman scattering signals is formed by an optical fiber beam splitter, a frequency doubling module, a first collimating lens, a first focusing mirror, a sample to be tested, a long-wave pass filter, a band-pass filter, a third focusing mirror, a Raman single-photon detector and a host computer;

[0010] A closed-loop optical path for detecting fluorescence signals is formed by an optical fiber beam splitter, a quadruple frequency module, a second collimating lens, a second focusing mirror, a sample to be tested, an adjustable narrow-band filter, a fourth focusing mirror, a fluorescence detector and a host computer;

[0011] The swept-frequency laser light source is divided into two laser paths through an optical fiber beam splitter, wherein one laser path is a double frequency light of the fundamental frequency light of the swept-frequency laser light source, and is used to detect the Raman scattering signal through a closed-loop optical path for detecting the Raman scattering signal; the other laser path is a quadruple frequency light of the fundamental frequency light of the swept-frequency laser light source, and is used to laser-induced detect the fluorescence signal through a closed-loop optical path for detecting the fluorescence signal; and the detection of LIF and RS is simultaneously achieved by using one swept-frequency laser light source.

[0012] Further, the optical centers of the double frequency module, the first collimating lens, the first focusing mirror, the long-wave pass filter, the band-pass filter and the third focusing mirror are located in a straight line and the angle between the optical center and the center line of the sample to be measured is 0 degrees;

[0013] Furthermore, the optical centers of the quadruple frequency module, the second collimating lens, the second focusing mirror, the adjustable narrowband filter and the fourth focusing mirror are located in a straight line and the angle between the optical center and the center line of the sample to be measured is 45 degrees.

[0014] The present invention has the following beneficial effects:

[0015] 1. The present invention uses a frequency doubling method of a swept laser light source to output doubled frequency laser and quadruple frequency laser respectively, and simultaneously performs LIF and RS measurements to obtain richer information in drug and hazardous chemical detection.

[0016] 2. The present invention uses a swept-frequency laser light source 2 with continuously adjustable wavelength, which is divided into two laser beams through an optical fiber beam splitter 4. One laser beam is a second-harmonic light of the fundamental frequency light, which is used to detect Raman scattering signals; the other laser beam is a fourth-harmonic light of the fundamental frequency light, which is used to detect laser-induced fluorescence signals. By using a swept-frequency laser light source 2 to simultaneously realize the detection of LIF and RS, the cost of the test device is effectively reduced.

[0017] 3. The present invention adopts Raman single-photon detector 16, adjustable narrow-band filter 17 and fluorescence detector 19 to realize synchronous measurement of Raman signal and fluorescence signal, without using expensive grating spectrometer and planar array / linear array detector, which greatly reduces the volume and cost of the test device; compared with the traditional solution based on grating spectrometer combined with planar array / linear array detector, the cost is reduced by more than 30%, the volume is reduced by more than 50%, and the miniaturization of the test device is easy to realize.

[0018] 4. The sample 23 to be tested in the present invention is excited by transmission. Compared with the reflective excitation method, the generated Raman and fluorescence signals are enhanced by 3-5 times. In order to ensure the quality of the fluorescence signal and the Raman signal, a long-wave pass filter 13 and a band-pass filter 14 are used to filter out interference such as scattering and back noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0020] Figure 2 is a Raman spectrum of a sample tested in an embodiment of the present invention;

[0021] Figure 3 is a fluorescence spectrum of a sample tested in an embodiment of the present invention;

[0022] Explanation of the accompanying numbers: 1-laser light source control module, 2-sweep laser light source, 3-main output optical fiber, 4-optical fiber beam splitter, 5-first light-splitting optical fiber, 6-double frequency module, 7-first collimating lens, 8-first focusing mirror, 9-second light-splitting optical fiber, 10-quadruple frequency module, 11-second collimating lens, 12-second focusing mirror, 13-long wave pass filter, 14-band pass filter, 15-third focusing mirror, 16-Raman single photon detector, 17-adjustable narrow band filter, 18-fourth focusing mirror, 19-fluorescence detector, 20-first signal transmission line, 21-second signal transmission line, 22-host computer, 23-sample to be tested. DETAILED DESCRIPTION

[0023] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein; on the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0024] like Figure 1 As shown, this embodiment discloses a transmission-type laser spectrum testing device based on a single swept-frequency light source.

[0025] The laser light source control module 1 is a current source with adjustable current, which is used to drive the swept-frequency laser light source 2 to work; the swept-frequency laser light source 2 (model ss3388-100, Micro-Optics Corporation of America) is a laser light source with continuously adjustable wavelength, and its emission wavelength scanning range is 1240-1380nm; the laser generated by the swept-frequency laser light source 2 is output through the main output optical fiber 3, and the laser output from the main output optical fiber 3 is divided into two lasers through the optical fiber beam splitter 4, which are output through the first splitting optical fiber 5 and the second splitting optical fiber 9 respectively; the laser power ratio output from the first splitting optical fiber 5 and the second splitting optical fiber 9 is 90:10, 80:20, 70:30 or 60:40.

[0026] The laser output by the first splitting optical fiber 5 is coupled to the double frequency module 6 to obtain visible light with a wavelength of 620nm-690nm. After the visible light is vertically incident on the first collimating lens 7 to compress the divergence angle, it is vertically compressed to a diameter of less than 1-3mm by the first focusing lens 8, and then vertically incident on the surface of the sample to be tested 23 to generate a scattering signal; the scattered signal passes through the sample to be tested 23 and vertically incident on the long-wave pass filter 13 to filter out the Rayleigh scattered light and the background light with a shorter wavelength, and then vertically incident on the bandpass filter 14, and the bandpass filter 14 further filters out other stray light except the Raman scattered light, so as to improve the test signal-to-noise ratio; the Raman scattered light then vertically passes through the third focusing lens 15 to enter the Raman single photon detector 16 (model S12426-05, Hamamatsu, Japan) to obtain a transmission Raman scattering signal of the corresponding wavelength, and the Raman scattering signal is then transmitted to the host computer 22 through the first signal transmission line 20 to obtain the Raman spectrum curve of the sample to be tested 23, as shown in FIG. Figure 2 shown.

[0027] Since the Raman frequency shift (the difference between the Raman scattered light frequency and the incident light frequency) is related to the laser wavelength, the present invention can obtain the Raman scattered light of the sample to be tested excited by lasers of different wavelengths by changing the emission wavelength of the swept-frequency laser light source 2.

[0028] The laser output by the second splitting optical fiber 9 is coupled to the quadruple frequency module 10 to output an ultraviolet laser with a wavelength of 310-345nm. The ultraviolet laser passes vertically through the second collimating lens 11 to compress the divergence angle, and then passes vertically through the second focusing lens 12 to compress the light spot to a diameter of 1-3mm, and is incident on the sample to be tested 23 at an incident angle of 45 degrees to generate a fluorescence signal. The fluorescence signal is transmitted through the sample to be tested 23 at a transmission angle of 45 degrees and then vertically incident on the adjustable narrowband filter 17 on the other side of the sample. The function of the adjustable narrowband filter 17 is to only pass fluorescence with a wavelength range of 350-750nm and a wavelength interval of 2-5 nm. Then, it passes vertically through the fourth focusing lens 18 and then vertically incident on the fluorescence detector 19 (model PMM02, American Sorebo Company) to obtain a fluorescence signal of the corresponding wavelength. The fluorescence signal is transmitted to the host computer 22 through the second signal transmission line 21 to obtain a fluorescence spectrum curve of the sample to be tested 23, as shown in FIG. Figure 3 Compared with visible light excitation, ultraviolet laser light source excitation of samples will produce stronger fluorescence spectrum.

[0029] The sample 23 to be tested may be a packaged transparent or translucent solid sample or a liquid sample.

[0030] The transmission laser spectroscopy testing device based on a single swept-frequency light source proposed in the present invention has the advantages of non-invasiveness, low cost, high sensitivity, high spatial and temporal resolution, etc. It has broad application prospects in the fields of hazardous chemicals detection, drug detection, etc. It can not only provide surface and deep structure information of the sample to be tested, but also realize multiple functions such as chemical composition identification.

Claims

1. A transmission-type laser spectrum testing device based on a single frequency-sweeping light source, comprising a laser source, a laser light source control module (1), an optical fiber beam splitter (4), a sample to be tested (23), a collection device, and a host computer (22); characterized in that: The laser source is a frequency-sweeping laser light source (2); the collection device comprises a Raman single-photon detector (16) and a fluorescence detector (19); The frequency sweeping laser light source (2) is connected to the optical fiber beam splitter (4) via the main output optical fiber (3); the optical fiber beam splitter (4) is connected to the double frequency module (6) via the first splitting optical fiber (5), and is connected to the quadruple frequency module (10) via the second splitting optical fiber (9); a first collimating lens (7) and a first focusing lens (8) are sequentially arranged at the front end of the double frequency module (6); a second collimating lens (11) and a second focusing lens (12) are sequentially arranged at the front end of the quadruple frequency module (10); The host computer (22) is connected to the Raman single-photon detector (16) via a first signal transmission line (20), and is connected to the fluorescence detector (19) via a second signal transmission line (21); a third focusing mirror (15), a bandpass filter (14), and a long-wave pass filter (13) are sequentially provided at the front end of the Raman single-photon detector (16); and a fourth focusing mirror (18) and an adjustable narrow-band filter (17) are sequentially provided at the front end of the fluorescence detector (19); A closed-loop optical path for detecting Raman scattering signals is formed by an optical fiber beam splitter (4), a frequency doubling module (6), a first collimating lens (7), a first focusing mirror (8), a sample to be tested (23), a long-wave pass filter (13), a band-pass filter (14), a third focusing mirror (15), a Raman single-photon detector (16) and a host computer (22); A closed-loop optical path for detecting a fluorescence signal is formed by an optical fiber beam splitter (4), a quadruple frequency module (10), a second collimating lens (11), a second focusing mirror (12), a sample to be tested (23), an adjustable narrow-band filter (17), a fourth focusing mirror (18), a fluorescence detector (19) and a host computer (22); The swept-frequency laser light source (2) is divided into two laser beams by an optical fiber beam splitter (4), wherein one laser beam is a double frequency light of the fundamental frequency light of the swept-frequency laser light source (2), and is used to detect the Raman scattering signal through a closed-loop optical path for detecting the Raman scattering signal; the other laser beam is a quadruple frequency light of the fundamental frequency light of the swept-frequency laser light source (2), and is used to laser-induced detect the fluorescence signal through a closed-loop optical path for detecting the fluorescence signal; and by using one swept-frequency laser light source (2), the detection of LIF and RS is simultaneously achieved.

2. The transmission laser spectrum testing device based on a single frequency sweeping light source according to claim 1, characterized in that: The optical centers of the double frequency module (6), the first collimating lens (7), the first focusing mirror (8), the long-wave pass filter (13), the band-pass filter (14) and the third focusing mirror (15) are located in a straight line, and the angle between the optical center and the center line of the sample to be measured (23) is 0 degrees.

3. The transmission-type laser spectrum testing device based on a single frequency-sweeping light source according to claim 2, characterized in that: The optical centers of the quadruple frequency module (10), the second collimating lens (11), the second focusing mirror (12), the adjustable narrowband filter (17) and the fourth focusing mirror (18) are located in a straight line, and the angle between the optical center and the center line of the sample to be measured (23) is 45 degrees.

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