CN113418609B - Raman spectrum testing system - Google Patents
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- 238000012360 testing method Methods 0.000 title claims abstract description 39
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- G01J3/44—Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
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Abstract
The utility model provides a Raman spectrum test system, including monochromatic light module, light path coupling and output module and signal detection module, wherein: the monochromatic light module comprises an ultrafast laser, the ultrafast laser is used for emitting ultrashort pulse laser, and the output wavelength of the ultrashort pulse laser is continuously adjustable; the light path coupling and output module is used for focusing the monochromatic light output by the monochromatic light module to the surface of a sample, exciting and collecting Raman scattered light, and filtering Rayleigh scattered light; and the signal detection module is used for receiving and detecting the Raman scattering light to obtain the Raman spectrum of the sample. The excitation light source of the Raman spectrum testing system has the characteristics of continuous adjustability in the ultra-wide band range, high power density, good monochromaticity and the like, the Raman spectrum testing system can conveniently switch different excitation wavelengths to realize Raman spectrum measurement, and the Raman spectrum testing system has the characteristics of simplicity in operation, high efficiency, strong adjustability, easiness in function expansion, wide application range and the like.
Description
Technical Field
The disclosure relates to the technical field of micro spectrometers, in particular to a Raman spectrum testing system.
Background
The Raman spectrum is used as a high-efficiency and nondestructive characterization technology for detecting material components and lattice vibration, and is widely applied to the fields of physics, chemistry, biomedicine, material science and the like. At present, the conventional single-grating-based raman spectrometer is usually used together with a single longitudinal mode laser and a cut-off filter matched with the laser wavelength. Lasers in the ultraviolet, visible, and near infrared wavelength ranges can be used as excitation light sources for raman spectroscopy, and commercially available gas, ion, or solid-state pumped continuous lasers typically have discrete single or multiple laser wavelengths, which are common raman spectroscopy excitation light sources. In a specific experiment requiring an excitation light source covering a wide energy range and similar output energy, it is often necessary to configure multiple and multiple types of lasers with discrete wavelengths for use. For example, when a spectrum whose raman signal intensity varies with the excitation light energy is studied (i.e., a "resonance profile" of a certain raman mode is measured), a plurality of lasers with similar output energies need to be used and matched with corresponding filters. The configuration has the advantages that firstly, the cost is high, the configuration is difficult to realize in a conventional laboratory, and secondly, the condition that the utilization rate of some lasers is low easily exists, so that the resource waste is caused. In a raman spectroscopy test system in the related art, a super-continuous white light source is used as a light source, and a plurality of optical elements are used for splitting light to obtain monochromatic light. Although the continuously adjustable monochromatic light can be obtained, the power of the obtained monochromatic light is greatly lost by using too many optical elements, the power of the monochromatic light reaching the surface of the sample is only hundreds of microwatts and is far less than the power which can be achieved by using a commercial single-frequency laser under the same condition, so that the application scene is limited, and the acquisition time is usually required to be prolonged for compensation in the actual Raman spectrum measurement. Therefore, finding suitable alternative light sources to increase the power of monochromatic light for application in measurement of more materials is an urgent technical problem.
At present, the tunable ultrafast laser is one of the main laser light sources for optical, optoelectronic, biological, medical research and military application research, and is widely applied to various spectrum researches related to nonlinear optics, and is a common instrument. The tunable ultrafast laser based on the nonlinear effect has the advantages that high-power pulse laser with continuously adjustable wavelength in a wide band range can be output, and the output of exciting light with different wavelengths can be realized according to different principles and configurations. However, the pulse width of the output pulse laser is usually in picosecond or femtosecond level, the corresponding spectral line width reaches more than ten nanometers, and the requirement of a narrow-line-width excitation light source required by Raman spectrum testing cannot be met, so that the output pulse laser cannot be applied to measurement of conventional Raman spectrum. Therefore, it is an urgent technical problem to reduce the line width of the pulsed laser by a simple and easy-to-operate method, so that the method can be applied to conventional raman spectroscopy measurement.
Disclosure of Invention
Technical problem to be solved
The present disclosure is directed to a raman spectroscopy test system to at least solve the problems of the prior art described above.
(II) technical scheme
In order to achieve the above object, the present disclosure provides a raman spectroscopy test system, comprising a monochromatic light module, a light path coupling and output module, and a signal detection module, wherein:
the monochromatic light module comprises an ultrafast laser, the ultrafast laser is used for emitting ultrashort pulse laser, and the output wavelength of the ultrashort pulse laser is continuously adjustable;
the optical path coupling and output module is used for focusing the monochromatic light output by the monochromatic light module to the surface of the sample, exciting and collecting Raman scattered light, and filtering Rayleigh scattered light;
and the signal detection module is used for receiving and detecting the Raman scattering light to obtain the Raman spectrum of the sample.
In some embodiments of the present disclosure, the monochromatic light module further includes:
the diffraction grating is used for enabling the ultrashort pulse laser to be diffracted and split, and in the light emitted by the diffraction grating, non-zero-order diffracted light is in a spectral band which is continuously arranged according to the wavelength;
the first reflector is used for reflecting the negative first-order diffracted light emitted by the diffraction grating;
the center of the aperture diaphragm is superposed with the optical axis of the negative first-order diffracted light reflected by the first reflecting mirror, the plane of the aperture diaphragm is vertical to the optical axis of the negative first-order diffracted light, and the beam width of the negative first-order diffracted light is limited according to the aperture size of the aperture diaphragm to obtain monochromatic light;
and the monochromatic light wavelength measuring device is used for measuring the wavelength of the monochromatic light.
In some embodiments of the disclosure, the diffraction grating and the first mirror are disposed on the same rotatable support, and the position of the negative first-order diffracted light relative to the aperture stop is adjusted by rotating the rotatable support to change a deflection angle of the diffraction grating and the first mirror relative to an optical axis of the ultrashort pulse laser.
In some embodiments of the present disclosure, the diffraction grating comprises a transmissive diffraction grating or a reflective diffraction grating.
In some embodiments of the present disclosure, the optical path coupling and outputting module comprises:
the beam splitter is fixed on a vertical two-dimensional angle adjusting frame and used for collimating the monochromatic light output by the monochromatic light module to a microscope objective;
a microscope objective lens, which is used for focusing the monochromatic light reflected by the beam splitter to the surface of the sample, exciting to obtain Raman scattered light, and collecting the Rayleigh scattered light from the sample and the Raman scattered light to transmit back to the beam splitter;
and the focusing lens is fixed on the three-dimensional adjusting frame, and the Raman scattering light can be accurately focused and incident to the signal detection module by adjusting the three-dimensional adjusting frame.
In some embodiments of the present disclosure, the optical path coupling and outputting module further comprises:
at least one tunable sideband filter positioned between the beam splitter and the focusing lens for filtering the Rayleigh scattered light.
In some embodiments of the disclosure, each of the tunable sideband filters is fixedly arranged on a two-dimensional vertically adjustable frame for adjusting a yaw angle of the tunable sideband filter relative to an optical axis of the raman scattered light.
In some embodiments of the present disclosure, a cut-off sideband of the tunable sideband filter is continuously adjustable with the yaw angle, and a transmittance of the tunable sideband filter for the raman scattered light is greater than or equal to 90%; the transmittance of the tunable sideband filter to the Rayleigh scattered light is less than 0.0001%.
In some embodiments of the present disclosure, the signal detection module comprises:
the spectrum detection device comprises a spectrometer and a detector, and is used for receiving the Raman scattering light and detecting to obtain the Raman spectrum of the sample. (III) advantageous effects
According to the technical scheme, the raman spectrum testing system disclosed by the invention has at least one or part of the following beneficial effects:
(1) The Raman spectrum testing system disclosed by the disclosure has the characteristics of continuously adjustable excitation light source in an ultra-wide spectral band range, high power density, good monochromaticity and the like by applying the ultra-fast laser with the output wavelength continuously adjustable in the wide spectral band range and using a small number of light splitting elements.
(2) The Raman spectrum testing system has the capability of continuously adjusting the cut-off side band of the excitation light and the filter, has the advantages of simplicity and convenience in operation, reasonable light path arrangement, high expandability and the like, and can conveniently realize the measurement of Raman spectrum under the excitation of any excitation light in the visible light to near infrared wave bands.
Drawings
Fig. 1 is a schematic structural diagram of a raman spectroscopy testing system in an embodiment of the present disclosure;
FIG. 2 is a spectrum diagram of ultra-short pulse laser light emitted by the ultrafast laser of FIG. 1 and monochromatic light emitted from the monochromatic light module;
FIG. 3 shows the G mode (1580 cm) of corner double-layer graphene measured by the Raman spectrum testing system in FIG. 1 under the excitation of monochromatic light with the energy of 2.14eV and 1.85eV respectively -1 ) (ii) a Raman spectrum of;
fig. 4 is a resonance profile of the raman intensity of the G mode of the corner double-layer graphene in the energy range of 1.68 to 2.21eV, measured by using the raman spectroscopy test system in fig. 1, and the raman intensities of the G mode of the corner double-layer graphene under different energy excitations are normalized by the first-order raman mode intensity of the diamond crystal.
[ description of main element symbols in the drawings ] of the embodiments of the present disclosure
10-a monochromatic light module;
101-ultrafast laser;
102-a diffraction grating;
103-a first mirror;
104-a first diaphragm;
105-a second diaphragm;
106-monochromatic light wavelength measuring device;
20-an optical path coupling and output module;
201-a second mirror;
202-a third mirror;
203-a beam splitter;
204-microscope objective;
205-sample;
206-a fourth mirror;
207-a first tunable sideband filter;
208-a second tunable sideband filter;
209-a focusing lens;
30-a signal detection module;
301-a slit;
302-a fifth mirror;
303-a diffraction grating;
304-a sixth mirror;
305-a detector.
Detailed Description
The utility model provides a Raman spectrum testing system, which comprises a monochromatic light module, a light path coupling and output module and a signal detection module, wherein the monochromatic light module comprises an ultrafast laser, the ultrafast laser is used for emitting ultrashort pulse laser, and the output wavelength of the ultrashort pulse laser is continuously adjustable; the light path coupling and output module is used for focusing the monochromatic light output by the monochromatic light module to the surface of the sample, exciting and collecting Raman scattered light and filtering Rayleigh scattered light; and the signal detection module is used for receiving and detecting the Raman scattering light to obtain the Raman spectrum of the sample. The Raman spectrum testing system disclosed by the disclosure has the characteristics of continuously adjustable excitation light source in an ultra-wide band range, high power density, good monochromaticity and the like by applying the ultra-fast laser with continuously adjustable output wavelength in the ultra-wide band range and using a small amount of light splitting elements.
To make the objects, technical solutions and advantages of the present disclosure more apparent, the present disclosure will be described in further detail below with reference to specific embodiments and the accompanying drawings. This disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity, and like reference numerals refer to like elements throughout.
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.
In those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.).
The present disclosure provides a raman spectroscopy test system, as shown in fig. 1, including a monochromatic light module 10, a light path coupling and output module 20 and a signal detection module 30, wherein the monochromatic light module 10 includes an ultrafast laser 101, the ultrafast laser 101 is used for emitting ultrashort pulse laser, and the output wavelength of the ultrashort pulse laser is continuously adjustable; the optical path coupling and output module 20 is configured to focus monochromatic light output by the monochromatic light module 10 onto the surface of the sample 205, excite and collect raman scattered light, and filter rayleigh scattered light; and the signal detection module 30 is configured to receive and detect the raman scattered light, so as to obtain a raman spectrum of the sample 205.
The light split by the ultrashort pulse laser through the diffraction grating 102 has enough monochromaticity, and further filtering is not needed by a band-pass filter. Therefore, the raman spectrum testing system can greatly increase the power of the monochromatic light reaching the surface of the sample 205 by milliwatt, and the linewidth of the monochromatic light is narrower, which is enough to meet the power and linewidth requirements of most raman spectrum measurements.
The monochromatic light module 10 further includes: a diffraction grating 102, a first mirror 103 and at least one aperture stop. The diffraction grating 102 is used for diffracting and splitting the ultrashort pulse laser, and the diffracted light of each level except the zero-order diffracted light in the light emitted by the diffraction grating 102 is a spectral band continuously arranged according to the wavelength; the first reflector 103 is used for reflecting the negative first-order diffracted light emitted by the diffraction grating 102; the center of an aperture diaphragm of at least one aperture diaphragm is superposed with the optical axis of the negative first-order diffracted light reflected by the first reflecting mirror 103, the plane of the aperture diaphragm is vertical to the optical axis of the aperture diaphragm, and the beam width of the negative first-order diffracted light is limited according to the aperture size of the aperture diaphragm to obtain monochromatic light; the monochromatic light wavelength measurement device 106 is used to measure the wavelength of the monochromatic light.
The diffraction grating 102 includes a transmissive diffraction grating or a reflective diffraction grating (not shown).
The diffraction grating 102 and the first reflector 103 are arranged on the same rotatable support, and the deflection angle of the diffraction grating 102 and the first reflector 103 relative to the optical axis of the ultrashort pulse laser is changed through rotation, so that the position of the negative first-order diffracted light relative to the aperture diaphragm is adjusted.
The optical path coupling and outputting module 20 includes: a beam splitter 203, a microscope objective 204 and a focusing lens 209. The beam splitter 203 is fixed on a vertical two-dimensional angle adjusting frame and is used for collimating monochromatic light output by the monochromatic light module 10 to the microscope objective 204; the microscope objective 204 is used for focusing the monochromatic light reflected by the beam splitter 203 to the surface of the sample 205, exciting and collecting the rayleigh scattered light and the raman scattered light from the sample 205 to transmit back to the beam splitter 203; the focusing lens 209 is fixed to a three-dimensional adjusting frame, and the three-dimensional adjusting frame is adjusted to accurately focus the raman scattered light to the signal detection module 30.
The optical path coupling and output module 20 further includes: at least one tunable sideband filter, for example: fig. 1 of this embodiment includes two tunable sideband filters, a first tunable sideband filter 207 and a second tunable sideband filter 208. The tunable sideband filter is located between the beam splitter 203 and the focusing lens 209, and can filter rayleigh scattered light to obtain pure raman scattered light.
The tunable sideband filter 207 is fixedly arranged on a two-dimensional vertically adjustable frame for finely adjusting the working angle thereof, and the two-dimensional vertically adjustable frame is fixedly arranged on a rotatable support for adjusting the deflection angle thereof relative to incident light. The focusing lens 209 is placed on the three-dimensional adjusting frame, and by adjusting the three-dimensional adjusting frame, the raman scattered light can be accurately focused and incident to the signal detection module 30; at least one second reflecting mirror 201, wherein the second reflecting mirrors 201 are all arranged on a vertical two-dimensional angle adjusting frame and are used for reflecting the monochromatic light irradiated on the surface of the sample 205 to the center of the beam splitter 203; at least one third mirror 202, the third mirror 202 for causing the raman scattered light reflected by the surface of the sample 205 of the beam splitter 203 to be incident on the focusing lens 209.
The cut-off sidebands of the tunable sideband optical filter 207 and the tunable sideband optical filter 208 are continuously adjustable along with the working angle, the cut-off wavelengths of the s wave and the p wave are not different in a certain range in the adjusting process, the transmittance of the tunable sideband optical filter 207 and the tunable sideband optical filter 208 to Rayleigh scattering light is more than or equal to 90%, and the transmittance of the tunable sideband optical filter 207 and the tunable sideband optical filter 208 to Rayleigh scattering light is less than 0.0001%.
The signal detection module 30 in the raman spectroscopy test system in the embodiment of the present disclosure includes: a spectroscopic probe apparatus comprising: a single grating spectrometer and detector 305, configured to receive the raman scattered light and perform detection, so as to obtain a raman spectrum of the sample 205.
The signal detection module 30 also includes responsive control circuitry. The single-grating spectrometer in the signal detection module 30 includes a slit 301, a fifth mirror 302, a diffraction grating 303, a sixth mirror 304, and a detector 305, where the raman scattering light from the slit 301 enters the fifth mirror 302, the signal light reflected by the fifth mirror 302 irradiates the diffraction grating 303, and the signal light dispersed by the diffraction grating 303 is collected by the sixth mirror 304 and reflected to the detector 305 for detection.
In some embodiments of the present disclosure, the mirror, beam splitter, tunable sideband filter are all fixed on two-dimensional vertically adjustable mounts, each of which can achieve fine adjustment in two dimensions. Part of the two-dimensional vertically adjustable frame is placed on a rotatable support that is removably placed on a post fixed to the spectrometer base. Based on the method, when different wavelengths of monochromatic light are switched and the cut-off sideband of the tunable sideband filter is changed, the light path can be quickly aligned and adjusted.
In addition, in some embodiments of the present disclosure, during the test using the raman spectroscopy test system, the monochromatic light wavelength measurement device 106 is also used to measure the wavelength of the monochromatic light after passing through the diaphragms 104 and 105; alternatively, the monochromatic light wavelength measuring device 106 may be a fiber optic spectrometer or other device capable of measuring the wavelength of the excitation light.
Specifically, the present disclosure is implemented such that the method includes operations S1 to S4 as follows:
operation S1: setting the output wavelength of the ultra-short pulse laser output by the ultra-fast laser 101, which should be covered in the working range of other optical elements in the device;
operation S2: the rotatable support where the transmission grating 102 and the first reflecting mirror 103 are located in the monochromatization optical module 10 is rotated, and the deflection angle of the diffraction grating 102 and the first reflecting mirror 103 relative to the incident light path is changed, so that the position where the negative first-order spectral band of the ultra-short pulse laser output by the ultrafast laser 101 reaches the first diaphragm 104 after being split by the transmission grating 102 is changed. The first diaphragm 104 and the second diaphragm 105 are used for limiting the size of the monochromatic light beam and filtering monochromatic light with different wavelengths to obtain monochromatic light irradiated to the surface of the sample 205. The wavelength of the monochromatic light emitted via the second diaphragm 105 is measured with a monochromatic light wavelength measuring device 106.
Operation S3: monochromatic light emitted from the monochromatic light module 10 is incident to the second reflecting mirror 201 by configuring the first reflecting mirror 103, and is reflected to the beam splitter 203 by the third reflecting mirror 202, and then the monochromatic light reflected by the beam splitter 203 is focused to the surface of the sample 205 by the microscope objective lens 204. Meanwhile, the rayleigh scattered light and the raman scattered light from the sample 205 are collected by the microscope objective 204, incident on the beam splitter 203, and reflected by the third mirror 202 to the first tunable sideband filter 207 and the second tunable sideband filter 208. The first tunable sideband filter 207 and the second tunable sideband filter 208 on the rotatable support are rotated to change their yaw angles with respect to the incident light and adjust their cut-off sidebands to the appropriate wavenumber, depending on the wavelength of the incident monochromatic light. The first tunable sideband filter 207 and the second tunable sideband filter 208 filter and attenuate the Rayleigh scattered light to at least 1/10 of the original 6 And most of the raman scattered light is transmitted through the single grating spectrometer, and is focused by the focusing lens 209 into the slit 301 of the single grating spectrometer in the signal detection module 30 for detection by the single grating spectrometer.
Operation S4: and repeating the operation S2 and the operation S3, and performing the test of the next monochromatic wavelength only by slightly adjusting the optical element in the optical path.
Application examples of a raman spectroscopy test system of the present disclosure are listed below.
The first embodiment is as follows:
as shown in fig. 1, the present embodiment discloses a raman spectroscopy testing system, which includes a monochromatic light module 10, an optical path coupling and output module 20, and a signal detection module 30.
As an optional embodiment, the Raman spectrum testing system is used for testing the Raman spectra of the corner double-layer graphene G mode and the diamond crystal first-order Raman mode to obtain a Raman spectrum resonance profile of which the ratio continuously changes within 1.68eV to 2.21eV along with the excitation wavelength of monochromatic light.
The monochromating optical module 10 at least comprises an ultrafast laser 101, a transmission grating 102, a reflecting mirror 103 and two diaphragms 104 and 105, and the monochromating optical module 10 is used for emitting and selecting monochromatic light. Optionally, a monochromatic light wavelength measuring device 106 is included for measuring the wavelength of the monochromatic light after passing through the second aperture 105.
Alternatively, the ultrafast laser 101 in the monochromating optical module 10 includes: the device comprises a Chameleon Ultra II self-mode-locking titanium gem laser, a tunable laser and a tunable laser, wherein the Chameleon Ultra II self-mode-locking titanium gem laser is used for providing a broadband tunable range of 680-1080 nm; the device comprises a Chameleon Compact OPO optical parametric oscillator, a tunable optical parametric oscillator and a tunable optical parametric oscillator, wherein the Chameleon Compact OPO optical parametric oscillator is used for being matched with a titanium sapphire laser to provide a broadband tunable range of 1000-1600 nm; the second harmonic accessory is used for being matched with the titanium sapphire laser and the optical parametric oscillator to provide frequency multiplication output and can respectively provide broadband tunable ranges of 340-540 nm and 500-800 nm. In most of the output wavelength range, it can provide output over hundreds of milliwatts, thereby ensuring that the ultrashort pulse laser still has enough power to excite the sample 205 after being split by the grating.
The transmission grating 102 and the first mirror 103 of the monochromatic light module 10 are fixed on a rotatable support so that their deflection angle with respect to the incident light path can be adjusted. When the transmission grating 102 and the first reflecting mirror 103 are placed as shown in fig. 1, the negative first-order spectral band of the ultra-short pulse laser output by the ultrafast laser 101 after being split by the transmission grating 102 reaches the first diaphragm 104, the position where the negative first-order diffraction spectral band reaches the diaphragm 104 can be changed by the deflection angle of the transmission grating 102 and the first reflecting mirror 103 relative to the incident light source, the size of the monochromatic light beam is limited by the diaphragm 104, and the diaphragm 105 is used for further limiting the size of the monochromatic light beam emitted by the diaphragm 104.
Optionally, the type of the transmission grating 102 in the monochromatic optical module 10 is FSTG-XVIS1274-920, the operating band is 360-830 nm, and the grating resolution is1274 mm- 1 。
The optical path coupling and outputting module 20 includes at least a second reflecting mirror 201 and a third reflecting mirror 202, a beam splitter 203, a micro objective 204, a fourth reflecting mirror 206, a first tunable sideband optical filter 207, a second tunable sideband optical filter 208, and a focusing lens 209, and is configured to reflect the monochromatic light obtained by the monochromatic light module 10 to the center of the beam splitter 203 through the two reflecting mirrors 201 and 202, guide the monochromatic light beam to the micro objective 204 by the beam splitter 203, focus the monochromatic light beam to the sample 205 through the micro objective 204, collect the rayleigh scattered light and the raman scattered light from the sample 205 through the micro objective 204, then reflect the collected light to the center of the beam splitter 203, obtain pure raman scattered light through the tunable sideband optical filters 207 and 208, and further focus the raman scattered light to the subsequent signal detecting module 30 through the focusing lens 209.
Optionally, in the optical path coupling and output module 20, the second reflecting mirror 201, the third reflecting mirror 202, and the fourth reflecting mirror 206 are all fixed on a two-dimensional vertically adjustable frame, so that their angles are two-dimensionally adjustable; the second reflecting mirror 201 is adjusted so that the monochromatic light beam can be incident on the center of the beam splitter 203.
Optionally, in the optical path coupling and output module 20, the beam splitter 203, the first tunable sideband filter 207 and the second tunable sideband filter 208 are respectively disposed on a two-dimensional vertically adjustable frame in a pluggable manner, so that the position and the yaw angle thereof can be precisely adjusted.
Further, the transmittance of the beam splitter 203 was 55% and the reflectance was 45%. The two-dimensional vertically adjustable mount of the beam splitter 203 also includes adjustment threads that enable further fine adjustment of the position and angle of the filters supported on the two-dimensional vertically adjustable mount.
Optionally, the tunable sideband filters 207 and the tunable long-wave sideband filters 208 are TLPs 01-628 (the tunable energy range of the cut-off sideband is 1.97-2.21 eV, and the tunable wavelength range of the cut-off sideband is 628-561 nm) and TLPs 01-704 (the tunable energy range of the cut-off sideband is 1.76-1.97 eV, and the tunable wavelength range of the cut-off sideband is 704-628 nm), and have a transmittance of greater than 90% in the pass band. Its two-dimensional vertically adjustable mount is fixed to a rotatable mount that is removably positioned on a post fixed to the spectrometer base, enabling further fine adjustment of the position and yaw angle of the tunable sideband filters 207 and 208.
Optionally, in the optical path coupling and output module 20, a leica microobjective with a numerical aperture NA =0.9 is used as the microobjective 204, and the diameter of the monochromatic spot of the sample 205 is1 to 2 μm.
The power of the monochromatic light reaching the surface of the sample 205 through the microscope objective 204 can reach the milliwatt level, which is enough to meet the power requirement of most Raman spectrum measurement.
Alternatively, the power of the monochromatic light reaching the surface of the sample 205 through the microscope objective 204 is reduced to 0.5mW using an attenuation sheet to avoid heating the sample 205 and burning the sample 205.
Optionally, the focusing lens 209 is disposed on the three-dimensional translation adjusting frame, and by adjusting three translation axes of the three-dimensional translation adjusting frame, the position of the focusing lens 209 can be adjusted not only in the two-dimensional vertical direction, but also in a direction perpendicular to the slit 301, so that the raman scattered light can be accurately incident and focused on the slit 301 of the signal detection module 30 for detection by the signal detection module 30.
The single-grating spectrometer in the signal detection module 30 includes a slit 301, a fifth mirror 302, a diffraction grating 303, a sixth mirror 304, and a detector 305, where raman scattered light from the slit 301 enters the fifth mirror 302, signal light reflected by the fifth mirror 302 is irradiated onto the diffraction grating 303, and the signal light dispersed by the diffraction grating 303 is collected by the sixth mirror 304 and reflected to the detector 305 for detection.
The signal acquisition and analysis process of the raman spectrum of the present embodiment includes the following operations S5 to S8:
operation S5: setting the central wavelength of the ultrashort pulse laser output by the ultrafast laser 101 to a value that should be covered within the working range of other optical elements in the device;
operation S6: the rotatable bracket where the transmission grating 102 and the first reflecting mirror 103 are located in the monochromatization optical module 10 is rotated, the deflection angle of the transmission grating 102 and the first reflecting mirror 103 relative to the incident light path is changed, and the position where the minus first-order diffraction light spectral band of the ultra-short pulse laser output by the ultrafast laser 101 reaches the first diaphragm 104 after being split by the transmission grating 102 is changed. The first aperture 104 and the second aperture 105 are used for limiting the size of the monochromatic light beam to obtain monochromatic light irradiated to the surface of the sample 205. The wavelength of the monochromatic light emitted via the second diaphragm 105 is measured with the monochromatic light wavelength measuring device 106.
Operation S7: monochromatic light emitted from the monochromatic light module 10 is incident to the second reflecting mirror 201 by configuring the first reflecting mirror 103, and is reflected to the beam splitter 203 by the third reflecting mirror 202, and then the monochromatic light reflected by the beam splitter 203 is focused to the surface of the sample 205 by the microscope objective lens 204. Meanwhile, the monochromatic light reflected light and the raman scattered light from the sample 205 are collected by the microscope objective 204, and then enter the beam splitter 203, and are reflected by the third mirror 202 to the first tunable sideband filter 207 and the second tunable sideband filter 208. The first tunable sideband filter 207 and the second tunable sideband filter 208 on the rotatable support are rotated to change their yaw angles with respect to the incident light and adjust their cut-off sidebands to the appropriate wavenumber, depending on the wavelength of the incident monochromatic light. The first tunable sideband filter 207 and the second tunable sideband filter 208 filter and attenuate the Rayleigh scattered light to at least 1/10 of the original 6 Most of the raman scattered light is transmitted through the focusing lens 209 and focused into the slit 301 of the single grating spectrometer in the signal detection module 30 for detection by the single grating spectrometer.
Operation S8: and repeating the operation S6 and the operation S7, and performing the test of the next monochromatic wavelength only by slightly adjusting the optical element in the optical path.
As shown in fig. 2, a spectrum diagram of the ultra-short pulse laser emitted by the ultra-fast laser 101 and the monochromatic light emitted by the monochromatic light module 10 with an energy of about 1.85eV is shown, and it can be seen from the diagram that the half-width of the ultra-short pulse laser emitted by the ultra-fast laser 101 is 13.6meV, and the half-width of the monochromatic light emitted by the monochromatic light module 10 is less than 1.0meV, so that the ultra-short pulse laser and the monochromatic light module have very good monochromaticity.
Next, the resonance profile of the G-mode of the corner double-layer graphene is tested by using the raman spectroscopy test system of the present embodiment.
As shown in FIG. 3, the Raman spectrum testing system of the present embodiment is used to measure the G mode (about 1580 cm) of corner double-layer graphene under the excitation of monochromatic light with energy of 2.14eV and 1.85eV respectively -1 ) The raman spectrum of (a).
Since the intensity of the raman signal is related to the laser power, obtaining the resonance intensity spectrum requires normalizing the excitation light power. As shown in fig. 4, in this embodiment, in order to obtain the relationship that the raman intensity of the G mode of the corner double-layer graphene measured by the raman spectroscopy testing system of this embodiment varies in the energy range of 1.68 to 2.21eV with respect to the monochromatic excitation light, the raman intensity of the G mode of the corner double-layer graphene under different energy excitations has been normalized by the first-order raman mode intensity of the diamond crystal, so as to obtain the resonance profile of the G mode of the corner double-layer graphene in this range.
It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only directions referring to the drawings, and are not intended to limit the protection scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. In the event of possible confusion for understanding of the present disclosure, conventional structures or configurations will be omitted, and the shapes and sizes of the components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure.
Unless otherwise indicated, the numerical parameters set forth in the specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". In general, the meaning of the expression is meant to encompass variations of a specified number by ± 10% in some embodiments, by ± 5% in some embodiments, by ± 1% in some embodiments, by ± 0.5% in some embodiments.
The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element relative to another or relative to a method of manufacture, and is used merely to allow a given element having a certain name to be clearly distinguished from another element having a same name.
In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.
The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.
Claims (6)
1. A Raman spectrum testing system comprises a monochromatic light module, a light path coupling and output module and a signal detection module, wherein:
the monochromatic light module comprises an ultrafast laser, at least one aperture diaphragm, a diffraction grating, a first reflecting mirror and a monochromatic light wavelength measuring device, wherein the ultrafast laser is used for emitting ultrashort pulse laser, and the output wavelength of the ultrashort pulse laser is continuously adjustable; the diffraction grating is used for enabling the ultrashort pulse laser to be diffracted and split, and in light emitted by the diffraction grating, non-zero-order diffracted light is in a spectral band which is continuously arranged according to wavelength; the first reflector is used for reflecting the negative first-order diffracted light emitted by the diffraction grating; the center of the aperture diaphragm is superposed with the optical axis of the negative first-order diffraction light reflected by the first reflector, the plane of the aperture diaphragm is vertical to the optical axis of the negative first-order diffraction light, and the beam width of the negative first-order diffraction light is limited according to the aperture size of the aperture diaphragm to obtain monochromatic light; the monochromatic light wavelength measuring device is used for measuring the wavelength of the monochromatic light;
the light path coupling and output module is used for focusing the monochromatic light output by the monochromatic light module to the surface of a sample, exciting and collecting Raman scattered light, and filtering Rayleigh scattered light;
the signal detection module is used for receiving the Raman scattering light and detecting the Raman scattering light to obtain a Raman spectrum of the sample;
the diffraction grating and the first reflector are arranged on the same rotatable support, and the deflection angle of the diffraction grating and the first reflector relative to the optical axis of the ultrashort pulse laser is changed by rotating the rotatable support, so that the position of the negative first-order diffracted light relative to the aperture diaphragm is adjusted;
wherein the diffraction grating comprises a transmissive diffraction grating or a reflective diffraction grating;
the monochromatic light module does not comprise a wide-band pass filter and a tunable narrow-band filter.
2. A raman spectroscopy testing system according to claim 1 wherein the optical path coupling and output module comprises:
the beam splitter is fixed on a vertical two-dimensional angle adjusting frame and used for collimating the monochromatic light output by the monochromatic light module to a microscope objective;
a microscope objective lens, which is used for focusing the monochromatic light reflected by the beam splitter to the surface of the sample, exciting to obtain Raman scattered light, and collecting the Rayleigh scattered light and the Raman scattered light from the sample to transmit back to the beam splitter;
and the focusing lens is fixed on the three-dimensional adjusting frame, and the Raman scattering light can be accurately focused and incident to the signal detection module by adjusting the three-dimensional adjusting frame.
3. A raman spectroscopy test system according to claim 2 wherein the optical path coupling and output module further comprises:
at least one tunable sideband filter positioned between the beam splitter and the focusing lens for filtering out the Rayleigh scattered light.
4. A raman spectroscopy test system according to claim 3 wherein each of the tunable sideband filters is fixedly mounted on a two-dimensional vertically adjustable mount for adjusting the yaw angle of the tunable sideband filter relative to the optical axis of the raman scattered light.
5. A Raman spectroscopy test system according to claim 4, wherein a cut-off sideband of the tunable sideband filter is continuously adjustable with the yaw angle, and a transmittance of the tunable sideband filter to the Raman scattered light is greater than or equal to 90%; the transmittance of the tunable sideband filter to the Rayleigh scattered light is less than 0.0001%.
6. A raman spectroscopy testing system according to claim 1 wherein the signal detection module comprises: the spectrum detection device comprises a spectrometer and a detector, and is used for receiving and detecting the Raman scattering light to obtain the Raman spectrum of the sample.
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| CN110289538A (en) * | 2019-07-01 | 2019-09-27 | 重庆文理学院 | A kind of high efficiency based on ultra-short pulse laser and the continuously adjustable extreme ultraviolet generation system of wavelength |
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