CN211602937U - Needle tip enhanced Raman spectrum microscopic imaging device - Google Patents

Abstract

The utility model provides a needle point enhanced Raman spectrum microscopic imaging device, which comprises an exciting light unit, a light source unit and a light source unit, wherein the exciting light unit is used for generating radial polarized light beams; the surface plasmon excitation unit is used for receiving the radial polarized light beam and exciting to generate surface plasmons; the scanning unit comprises a scanning probe, and the scanning probe and the surface plasmon polariton are hybridized to form a surface plasmon polariton field hybridization unit; the exciting light unit, the detecting unit and the scanning unit are all connected with the monitoring unit. The surface plasmon is generated by radial polarized light excitation and focused to generate a virtual surface plasmon probe, a gap structure formed between the scanning probe and the surface plasmon unit is hybridized with the surface plasmon to generate a surface plasmon field hybridization unit, the surface local electric field is enhanced, an enhanced Raman spectrum signal of a sample to be measured is obtained, and the microscopic imaging of the sample is further realized by utilizing the Raman spectrum obtained by measurement.

Description

Needle tip enhanced Raman spectrum microscopic imaging device

Technical Field

The utility model belongs to the technical field of the micro-spectrum image device, concretely relates to micro-image device of needle point reinforcing raman spectrum.

Background

Raman spectroscopy is a common spectroscopic method of detecting chemical bonds, symmetry, or other chemical composition and structural information of a sample molecule. A rapid, simple, reproducible and non-invasive qualitative and quantitative analysis can be provided.

Tip-Enhanced Raman spectroscopy (TERS) technology is a combination of Scanning Probe Microscopy (SPM) and Raman spectroscopy. The TERS technology can meet the analysis requirement on chemical substances on a surface interface in the nanometer science and the nanometer technology, and has high spatial resolution and obvious enhancement effect on molecular Raman signals. The principle is that an Ag or Au tip with the curvature radius of tens of nanometers is controlled to be very close to a sample (such as 1nm) through an SPM control system, when incident light irradiates on the tip with proper wavelength, the tip is excited by laser to generate physical mechanisms such as local surface plasmon resonance, lightning rod effect and the like, so that strong local electromagnetic field enhancement can be generated in the range of several nanometers to ten nanometers near the tip, and the metal tip can be regarded as a nano light source with high power density, so that the Raman signals of substrates or adsorbed molecules on the substrates which are positioned right below the tip are greatly enhanced. The high-spatial-resolution chemical composition imaging of the TERS technology provides powerful technical support for solving a plurality of important scientific problems of single molecule science, such as obtaining information of the morphology, chemical bonds and the like of a single molecule, and has the advantages of label-free, in-situ, real-time, rapid acquisition of biomass information and the like.

Surface Plasmon Polaritons (SPP) are electromagnetic waves bound to the interface between metal and dielectric material or the Surface of a metal film, which are formed by coupling and resonating free electrons and incident photons on the Surface of metal, and can localize a large amount of light wave energy on the interface between metal and dielectric material, thereby forming a strong near-field enhancement effect.

The TERS technology is classified into three typical Illumination modes, i.e., a Side Illumination Mode (in which a laser light source irradiates the tip of a probe at a certain angle from the Side of the probe), a Top Illumination Mode (in which a laser light source irradiates the tip of a probe from the Top of the probe), and a Bottom Illumination Mode (in which a laser light source irradiates the tip of a probe from below the probe), according to the difference in the relative positions of the laser beam and the tip of the probe.

Both the side illumination mode and the top illumination mode have the limitation of working distance, and an objective lens with too large numerical aperture cannot be used, so that the enhancement direction of a spectral signal is limited to a certain extent; while the bottom illumination mode can use an objective lens with a larger numerical aperture to increase the intensity of the incident light field and enhance the spectral signal, generally, for a transparent sample, a non-transparent sample will cause the laser emission intensity to decrease, thereby affecting the intensity of the spectral signal.

The existing needle-tip-enhanced Raman spectrum microscopic imaging device generally comprises a laser light source, a scanning probe microscope, a microscopic imaging system and a spectrometer, wherein the laser light source irradiates the tip end of a scanning probe of the scanning probe microscope to excite surface plasmons, the spectrometer detects Raman spectrum signals and Raman spectrum scanning imaging, and the microscopic imaging system scans and images a sample so as to know whether the Raman spectrum signals of the sample are enhanced or not and the enhancing degree. Since the intensity of raman spectrum signals is related to the intensity of incident light field and surface plasmons, it is common first practice to use an objective lens with a large numerical aperture to increase the incident light field intensity; the second approach is to use a metal film to form a Gap structure with the tip of the scanning probe to enhance the raman spectrum signal. However, the first approach is only effective for transparent samples, while for non-transparent samples the incident light field intensity is reduced; although the second method can solve the problem of the decrease of the incident light field intensity caused by the non-transparent sample, the intensity of the obtained raman spectrum signal still needs to be further improved.

SUMMERY OF THE UTILITY MODEL

The utility model discloses the technical problem that will solve lies in that the micro-imaging device of current raman spectrum signal intensity is lower, consequently provides a micro-imaging device of needle point reinforcing raman spectrum that raman spectrum signal intensity is strong, spatial resolution is high.

Therefore, the utility model provides a needle point reinforcing raman spectroscopy microscopic imaging device, include:

the excitation light unit is used for generating radial polarized light beams and enabling the radial polarized light beams to be incident to the surface plasmon excitation unit;

the surface plasmon excitation unit is used for receiving the radial polarized light beam and exciting to generate surface plasmons;

the scanning unit comprises a scanning probe, and the scanning probe and the surface plasmon are hybridized to form a surface plasmon field hybridization unit;

the detection unit is used for detecting the Raman spectrum of the sample to be detected and scanning and imaging;

the monitoring unit displays the Raman spectrum of the sample to be detected and performs imaging according to the characteristic spectrum of the sample to be detected;

the exciting light unit and the detecting unit are both connected with the monitoring unit, and the scanning unit is sequentially connected with the detecting unit and the monitoring unit.

Optionally, the surface plasmon excitation unit includes:

an objective lens; and

the metal film is plated on the objective lens, the radial polarized light beams are incident on the metal film and excited to generate the surface plasmons and are focused to generate the surface plasmon virtual probe, and the surface plasmon virtual probe and the scanning probe are hybridized to form the surface plasmon field hybridization unit.

Optionally, in the needle-tip-enhanced raman spectroscopy microscopic imaging apparatus, the thickness of the metal film is 40-50nm, and the numerical aperture of the objective lens is greater than 1.45.

Optionally, in the tip-enhanced raman spectroscopy microscopic imaging apparatus, a gap is formed between the scanning probe and the metal film, and the gap is smaller than 10 nm.

Optionally, the excitation light unit includes:

the laser element is used for generating a laser beam with a preset wavelength;

and the polarizing element, the collimating element and the vortex wave plate are sequentially arranged between the laser element and the objective lens along the output direction of the light path of the laser beam, and the laser beam is converted into radial polarized light through the polarizing element, the collimating element and the vortex wave plate and is incident to the objective lens.

Optionally, in the needle-tip-enhanced raman spectroscopy microscopic imaging apparatus, the radial polarized light is collimated by the lens group and then outputs parallel light.

Optionally, in the needle-tip-enhanced raman spectroscopy microscopic imaging apparatus, the surface plasmon excitation unit further includes:

and the beam splitting element is arranged between the light beam incidence end of the objective lens and the light beam exit end of the vortex wave plate and is used for transmitting the radial polarized light to the objective lens and exciting the radial polarized light on the metal film to generate the surface plasmon.

Optionally, in the needle-tip-enhanced raman spectroscopy microscopic imaging apparatus, the beam splitting element is a beam splitter or a dichroic mirror.

Optionally, the needle-tip-enhanced raman spectroscopy microscopic imaging apparatus includes:

a filter element;

a spectrometer; and

a CCD image sensor;

the light filtering element, the spectrometer and the CCD image sensor are connected with the beam splitting element through a horizontal linear light path, Raman scattered light of a sample to be detected is coupled through the objective lens to obtain coupled light, the coupled light is reflected to the beam splitting element, the coupled light is transmitted by the light filtering element and then enters the spectrometer and the CCD image sensor, and the Raman spectrum of the sample to be detected is displayed and imaged according to the characteristic spectrum by the monitoring unit.

Optionally, in the tip-enhanced raman spectroscopy microscopic imaging apparatus, the scanning probe is a probe plated with a metal film.

The utility model discloses technical scheme has following advantage:

1. the utility model provides a micro-imaging device of needle point reinforcing raman spectrum, including exciting light unit, surface plasmon excitation unit, surface plasmon field hybridization unit, scanning unit, detecting element and monitor cell, exciting light unit produces radial polarized light and incides to surface plasmon excitation unit to excite and produce surface plasmon and focus and produce the virtual probe of surface plasmon, scanning unit includes the scanning probe, the virtual probe of surface plasmon and scanning probe carry out hybridization also be coupling oscillation, and an enhanced surface local field intensity is obtained in a gap structure formed between the scanning probe and the surface plasmon unit, the surface plasmon virtual probe and the scanning probe jointly act to enhance a surface local electric field to obtain an enhanced Raman spectrum signal, the intensity of the excitation local field is enhanced, and a sample to be detected is stimulated to generate surface enhanced Raman scattering.

2. The utility model provides a pair of needle point reinforcing raman spectroscopy micro-imaging device, adopt thickness to be 40-50 nm's metal film, and adopt numerical aperture NA to be greater than 1.45's objective makes the incident light intensity of incidenting to the sample that awaits measuring bigger, make the exciting light incide to arouse through objective and produce surface plasmon and focus on the metal film and form the virtual probe of surface plasmon, be less than 10nm through the clearance structure between control scanning probe and the metal film, make the virtual probe of surface plasmon produce the hybridization effect in clearance structure, arouse the enhancement of local electric field, the raman spectrum signal of reinforcing surface local field intensity, the spatial resolution who scans probe detection has still been improved simultaneously.

3. The utility model provides a pair of micro-imaging device of needle point reinforcing raman spectrum, scanning probe are for plating the probe of metallic film, produce radial polarized light through laser element, on inciting to objective, the metallic film of excitation objective produces surface plasmon and focuses on and produce the virtual probe of surface plasmon, produces the hybridization effect through producing between the clearance structure that surface plasmon and metallic probe formed, plays reinforcing raman spectrum signal's intensity.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a structural diagram of a needle-tip enhanced raman spectroscopy microscopic imaging apparatus in an embodiment of the present invention;

fig. 2 is a structural diagram of an excitation light unit and a surface plasmon excitation unit of the needle-tip-enhanced raman spectroscopy microscopic imaging apparatus in an embodiment of the present invention;

fig. 3 is an optical path diagram of the needle-tip enhanced raman spectroscopy microscopic imaging apparatus according to the embodiment of the present invention;

fig. 4 is a raman spectrogram of the analysis of the sample to be measured and a raman spectrogram of the analysis of the sample to be measured obtained by only using the metal film to obtain the surface plasmon virtual probe;

FIG. 5 is a Raman spectrum of a sample to be measured analyzed by a conventional Raman spectroscopy microimaging apparatus and a Raman spectrum of a sample to be measured by a microimaging apparatus without using a dummy probe and a scanning probe in the prior art;

FIG. 6 is a microscopic image of the spatial distribution of carbon nanotubes in a standard sample scanned by a scanning probe;

FIG. 7 is a resolution of the profile distribution of the dashed line in FIG. 6;

FIG. 8 illustrates spatial resolution of a sample under test according to an embodiment of the present invention;

fig. 9 is a raman spectrum of the carbon nanotube of the standard sample.

Description of reference numerals:

10-an excitation light unit; 101-a laser element; 102-a polarizing element; 103-a collimating element; 1031-a first convex lens; 1032-a second convex lens; 104-vortex wave plate;

20-surface plasmon excitation unit; 201-a beam splitting element; 202-objective lens;

30-a surface plasmon field hybridization unit;

40-a scanning unit; 401-scanning probe;

50-a detection unit; 501-a filter element; 5011-first filter; 5012-a second filter; 502-spectrometer; 503-CCD image sensor;

60-a monitoring unit;

70-lighting unit.

Detailed Description

The technical solution of the present invention will be described clearly and completely with reference to the accompanying drawings, and obviously, the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Example 1

A tip-enhanced raman spectroscopy microscopic imaging apparatus of the present embodiment, as shown in fig. 1 to 9, includes an excitation light unit 10, a surface plasmon excitation unit 20, a surface plasmon field hybridization unit 30, an illumination unit 70, a scanning unit 40, a detection unit 50, and a monitoring unit 60; the excitation light unit 10 is configured to generate a radial polarized light beam, and to inject the generated radial polarized light beam onto the surface plasmon excitation unit 20; the surface plasmon excitation unit 20 is configured to receive the radial polarized light beam, irradiate the radial polarized light beam, and excite a surface plasmon field by using energy of the radial polarized light beam; a scanning unit 40 including a scanning probe 401; the scanning probe 401 is used for scanning a sample to be detected, the scanning probe is also used for hybridizing with a surface plasmon to obtain a surface plasmon field hybridization unit 30, a gap structure (not shown) is arranged between the scanning probe and the surface plasmon, namely a gap structure common in the field, the surface plasmon field hybridization unit is a surface enhanced local field formed in the gap structure, and a Raman spectrum signal of the sample to be detected is enhanced by utilizing a hybridization effect; the detection unit 50 is used for detecting the Raman spectrum of the sample to be detected and scanning and imaging; the monitoring unit 60 is used for imaging and displaying the Raman spectrum of the sample to be detected; the excitation light unit 10 and the detection unit 50 are both connected with the monitoring unit 60, and the scanning unit 40 is sequentially connected with the detection unit 50 and the monitoring unit 60; illumination unit 70 is disposed at the bottom of surface plasmon excitation unit 20, and is used to illuminate a sample to be measured.

The utility model discloses a research finds, to the hybridization effect of surface plasmon field hybridization unit 30 to the reinforcing effect of detection spectral signal with following several factors are relevant: the thickness of the metal film influences the strength of surface plasmons generated on the metal film by excitation and whether the surface plasmons can be generated by excitation; the numerical aperture of the objective lens influences the incident intensity of radial polarized light, so that the intensity of surface plasmons generated on the metal film by excitation is influenced; the structure of the gap between the scanning probe 401 and the metal film affects the surface local field strength and thus the intensity of the raman spectral signal of the surface local field strength.

The surface plasmon excitation unit 20 comprises an objective lens 202 and a metal film plated on the objective lens 202, specifically, the metal film is plated on a glass slide of the objective lens 202, the thickness of the metal film is selected to be 40-50nm, preferably 45nm, and a beam splitting element 201 is arranged at an incident end of the objective lens 202, namely, at the bottom as shown in fig. 3, specifically, the beam splitting element 201 is arranged between the light beam incident end of the objective lens 202 and the vortex wave plate 104, and is used for reflecting the radial polarized light generated by the excitation light unit 10 to the objective lens 202, and the radial polarized light is irradiated on the metal film through the objective lens to excite the surface plasmon and focus the surface plasmon virtual probe. Specifically, the objective lens 202 is a high-NA objective lens, and the numerical aperture NA of the high-NA objective lens needs to be greater than 1.45, for example, an objective lens with a numerical aperture NA of 1.49 or an objective lens with a numerical aperture NA of 1.70; the utility model discloses the people finds through experimental study that the numerical aperture of objective 202 has great influence to the production of surface plasmon, when measuring in the liquid environment, the objective of current high numerical aperture objective (NA ═ 1.25) can't arouse under the illumination of polarized light beam and produce surface plasmon, need numerical aperture NA > 1.45 can effectively arouse and produce surface plasmon, the special case even needs numerical aperture NA > 1.70's objective; for example, the utility model discloses a numerical aperture NA of the objective that needle point reinforcing raman spectroscopy microscopic imaging device adopted is 1.49, and the radial polarized light that the exciting light produced incides the sample that awaits measuring after beam splitting component reflects to objective 202, excites on the metallic film to produce surface plasmon and focus and produce the virtual probe of surface plasmon.

In order to enable the utility model discloses a needle point reinforcing raman spectroscopy microscopic imaging device has higher signal, the utility model people discover through research that the thickness of metal film has very important effect to the production of surface plasmon, the thickness of metal film if too thin then can not arouse and produce the surface plasmon, the thickness of metal film too thick can cause the surface plasmon that arouses and produce can't pierce through the metal film, can't produce the hybridization effect with the clearance structure between scanning probe 401 and the metal film, can't form surface plasmon field hybridization unit, thereby can't realize surface plasmon near field reinforcing; the thickness of the metal film obtained by the utility model through multiple times of experimental optimization is more than 25nm, preferably 40-50nm, and more preferably 45 nm; the metal film with the thickness can ensure the efficiency and the effect of the surface plasmon excitation. The material of the metal film may be conventional gold, silver, aluminum, or the like, and is not particularly limited and described.

For the gap structure between the scanning probe 401 and the metal film, the utility model is obtained by theoretical research and multiple test optimization, the gap structure is preferably larger than 1nm and smaller than 10nm, the surface plasmon virtual probe generated by surface plasmon focusing and the scanning probe generate hybridization effect in the gap structure to form a new surface plasmon optical field, and the local field strength is high; research of utility model people obtains that tunneling effect is possible to occur when the gap structure is less than 1nm, so that the hybrid field strength is reduced; when the size is larger than 10nm, for example, 15nm, the utility model discloses a research finds that the hybrid field intensity of this gap structure can also sharply reduce to make the sensitivity of scanning probe 401 detection reduce.

In order to ensure the detection sensitivity of the scanning probe 401, in use, the monitoring unit 60 controls the scanning probe 401 to move, so that the scanning probe 401 and the surface plasmon virtual probe generated by the excitation of the surface of the metal film can be aligned, and as the intensity of the surface plasmon virtual probe at the position of the central region becomes larger, the more the scanning probe 401 scans the position and the surface plasmon virtual probe pair becomes aligned, the scattered light will be enhanced, so that the higher the detection sensitivity of the scanning probe 401 is, the stronger the resulting raman spectrum signal is. The surface plasmons penetrate through the metal film and are subjected to hybridization reaction with the gap structure in the propagation process to generate coupling oscillation, and the surface plasmons virtual probe generated on the surface of the metal film by exciting light and the scanning probe 401 act together to enhance Raman spectrum signals of surface local field intensity.

As for the excitation light unit 10, the excitation light unit 10 includes a laser element 101, a polarization element 102, a collimating element 103, and a vortex wave plate 104, the laser element 101 is configured to generate a laser beam having a preset wavelength, such as a visible light wavelength range, and the laser beam is incident to the polarization element 102; the polarizing element 102 converts the incident laser beam into linearly polarized light, and the linearly polarized light is incident on the collimating element 103; the collimating element 103 performs beam expanding and collimating on the incident linearly polarized light to obtain parallel light, and the parallel light is incident to the vortex wave plate 104; the vortex wave plate 104 converts the parallel light into radial polarized light, and the radial polarized light is incident to the surface plasmon excitation unit 20, that is, to the objective lens, and is irradiated on the metal film to be excited to generate surface plasmons, and laser is focused to generate the surface plasmon virtual probe. Specifically, as shown in fig. 3, the laser element 101 is, but not limited to, a conventional he-ne laser, the polarizing element 102 is, but not limited to, a conventional polarizer, the collimating element 103 is, but not limited to, a positive lens group, the positive lens group includes two first convex lenses 1031 and second convex lenses 1032 coaxially arranged at intervals, a focal length of the first convex lenses 1031 is smaller than a focal length of the second convex lenses 1032, and the laser beam is collimated by the first convex lenses 1031 and the second convex lenses 1032 and then outputs parallel light; a positive lens and a negative lens may be used as long as the light beams emitted from the laser element 101 can be collimated to output parallel light; in physical position, the laser element 101, the collimating element 103 and the vortex wave plate 104 are located on the same horizontal straight-line optical path and are all located at the bottom of the surface plasmon excitation unit 20, that is, the laser beam is incident to the surface plasmon excitation unit 20 from the bottom; more specifically, along the optical path direction, a mirror is disposed behind the vortex wave plate 104, that is, to the left of the vortex wave plate 104 as shown in the figure, an included angle between the mirror and the horizontal direction is 135 °, and a mirror disposed along the vertical direction is further disposed above the mirror, the number of the mirrors may be other, for example, one, three, and the like, and the radial polarized light is reflected by the two mirrors in sequence and then enters the surface plasmon excitation unit 20. To the utility model discloses a radial polarized light is annular vortex light beam, can effectually utilize the energy of incident light to deexcite the surface plasmon light field to the focus obtains the virtual probe of surface plasmon.

For the surface plasmon excitation unit 20, the surface plasmon excitation unit includes an objective lens 202, a metal film (not shown) and a beam splitting element 201, the beam splitting element 201 is a semi-reflective and semi-transparent structure, but not limited to a conventional beam splitter or dichroic mirror, the beam splitting element 201 is disposed at the bottom end of the objective lens 202, and is located on the optical path of the laser beam, the beam splitting element 201 is disposed at an angle of 135 ° with the horizontal direction, the radial polarized light is divided into two parts, i.e., a first beam and a second beam, after being incident on the beam splitting element 201, the first beam is reflected and vertically incident on the objective lens 202, and the second beam is transmitted through the beam splitting element 201. To objective 202, a layer of metal film has been plated on objective 202's the glass substrate, and the sample that awaits measuring is placed on the glass substrate, and surface plasmon produces and pierces through the metal film and enters into in the clearance structure and the metal film on the scanning probe produces the hybridization effect in order to form surface plasmon field hybridization unit 30 between the interface of sample that awaits measuring and metal film, the utility model discloses a surface plasmon field hybridization unit is the enhancement mode of surface plasmon.

The laser beam is incident on the metal film on the objective lens 202, the scanning probe 401 detects the raman scattering light of the sample to be detected and obtains coupled light under the coupling action of the objective lens 202, the coupled light is reflected to the beam splitting element 201 and then transmitted to the detection unit 50 through the filter element 501, and the monitoring unit 60 performs imaging display on the raman spectrum of the sample to be detected. Specifically, a light filtering element 501, a lens, a spectrometer 502 and a CCD image sensor 503 are sequentially disposed on a reflection light path of the beam splitting element 201, and in physical position, the beam splitting element 201, the light filtering element 501, the lens, the spectrometer 502 and the CCD image sensor 503 are on the same horizontal straight light path, and the horizontal straight light path is parallel to the horizontal straight light path of each component of the excitation light unit 10; the filter element 501 includes a first filter 5011, that is, a filter located on the left side in fig. 3, and a second filter 5012, that is, a filter located on the right side in fig. 3, where the two filters symmetrically arranged from left to right constitute the filter element, the left filter, that is, the first filter 5011, is arranged at an angle of, for example, 135 ° with respect to the horizontal line, the right filter, that is, the second filter 5012, is arranged at an angle of, for example, 45 ° with respect to the horizontal line, and the laser beam is reflected by the reflector onto the first filter 5011 and reflected to the beam splitting element 201, so that a part of the light path of the laser beam incident on the metal film and the light path reflected by the sample to be measured are coincident, that. The structure and operation of the filter element and the lens are not limited or described herein; spectrometer 502 is also a conventional raman spectrometer of the prior art and the specific structure and operation are not limited or described. The filter element is arranged to filter out the excitation light wavelength and only allow the raman spectrum wavelength of the sample to be measured to pass through and be incident on the spectrometer and the CCD image sensor. The filter element 501 may filter out light of the sample to be measured reflected by the metal film, so that the probe light is transmitted and incident to the spectrometer 502 and the CCD image sensor 503.

The utility model also comprises a scanning platform (not shown), the scanning probe 401 is movably arranged on the scanning platform, the scanning platform is connected with the monitoring unit 60, and the synchronization of the monitoring unit 60, the image sensor 503 and the scanning platform is realized; a sample to be detected is placed on the scanning platform, and the monitoring unit 60 can control the scanning probe 401 to move to perform scanning detection on the sample to be detected, so that a Raman spectrogram of the sample to be detected is obtained and is displayed on the monitoring unit 60 in an imaging manner; the scanning probe 401 is sequentially connected with the spectrometer 502 and the monitoring unit 60, the scanning probe 401 is used for detecting the surface morphology and the spectrum information of the sample to be detected and transmitting the information to the spectrometer, the spectrometer is used for detecting the Raman spectrum of the sample to be detected and is used for Raman spectrum scanning imaging of the sample to be detected, and the Raman spectrum scanning imaging of the sample to be detected is transmitted to the monitoring unit 60 for imaging display. Optionally, the scanning platform of the present invention is but not limited to an atomic force microscope, and the scanning probe 401 is but not limited to an atomic force microscope probe, because the accuracy of the atomic force microscope is higher, the present invention is preferably an atomic force microscope and an atomic force microscope probe; the utility model discloses a scanning probe is metal probe or plates the probe of metallic film. The scanning probe 401 can be disposed on the scanning platform by a conventional atomic force microscope probe micro-cantilever (not shown), and the specific structure and operation principle are not limited and described herein.

The monitoring unit 60 of the present invention comprises a control system (not shown) and a display system (not shown), and the present invention is preferably a computer or a computer.

The utility model discloses an illumination element 70 includes light source, beam splitting mirror, lens and camera, and light source, beam splitting mirror and beam splitting component 201 are in same vertical light path, and the spectroscope is located beam splitting component bottom and is 45 contained angles with the water flat arrangement, and the camera sets up in the left side of beam splitting mirror, and lens are located between beam splitting mirror and the camera, and lens, camera and beam splitting mirror are located same horizontal straight line light path; light reflected by the sample is partially transmitted through the back of the beam splitting element 201 and reflected by the beam splitter to the camera. The illumination source is preferably a white light source.

The utility model discloses a micro-imaging device of needle point reinforcing raman spectrum's raman spectral signal reinforcing can learn through the raman spectrogram of the sample that awaits measuring of spectrum appearance test, as shown in figure 4, a shows in the figure that the utility model discloses a micro-imaging device surveys the raman spectral signal intensity of the sample that awaits measuring that obtains, and what b shows adopts the focusing to form virtual probe on the metallic film, surveys the raman spectral signal intensity of the sample that awaits measuring that obtains through virtual probe; as shown in fig. 5, the conventional raman spectroscopy micro-imaging device shown in fig. c also has no raman spectroscopy signal intensity of the sample to be measured obtained by detecting the virtual probe, and d shown in the figure is the raman spectroscopy signal intensity of the sample to be measured obtained by detecting the gap structure between the scanning probe and the metal film without generating the virtual probe of the surface plasmon by the metal film, and it can be obviously seen from fig. 4 and 5 that the raman spectroscopy signal intensity of the needle-tip-enhanced raman spectroscopy micro-imaging device of the present invention is higher.

The resolution of the needle-tip enhanced raman spectroscopy micro-imaging device of the utility model is also enhanced, as shown in fig. 6 to 9, the resolution is calibrated by using the carbon nanotube as a standard sample, and fig. 6 is a nanotube space distribution micro-image obtained by scanning the needle-tip enhanced raman spectroscopy micro-imaging device of the utility model; FIG. 7 is a graph of the profile corresponding to the dashed line in FIG. 6, with the abscissa indicating the spatial position of the carbon nanotubes, where the spatial position indicates the spatial dimension of the carbon nanotubes, and the ordinate indicating the height of the carbon nanotubes, resulting in a scan resolution of 43 nm; FIG. 8 shows that the spatial resolution of the sample to be measured scanned by the needle-tip enhanced Raman spectroscopy microscopic imaging apparatus of the present invention reaches 13.5 nm; fig. 9 corresponds to a raman spectrum of the carbon nanotube of the standard sample.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications can be made without departing from the scope of the invention.

Claims (10)

1. A needle tip enhanced Raman spectroscopy microscopic imaging apparatus, comprising:

an excitation light unit (10) for generating a radially polarized light beam and making the radially polarized light beam incident on the surface plasmon excitation unit (20);

the surface plasmon excitation unit (20) is used for receiving the radial polarized light beam and exciting to generate surface plasmons;

a scanning unit (40) comprising a scanning probe (401), wherein the scanning probe (401) is hybridized with the surface plasmon to form a surface plasmon field hybridization unit (30);

the detection unit (50) is used for detecting the Raman spectrum of the sample to be detected and scanning and imaging;

the monitoring unit (60) displays the Raman spectrum of the sample to be detected and images according to the characteristic spectrum of the sample to be detected;

the excitation light unit (10) and the detection unit (50) are both connected with the monitoring unit (60), and the scanning unit (40) is sequentially connected with the detection unit (50) and the monitoring unit (60).

2. The needle-tip-enhanced raman spectroscopy microscopic imaging device according to claim 1, wherein said surface plasmon excitation unit (20) comprises:

an objective lens (202); and

and the metal film is plated on the objective lens (202), the radial polarized light beams are incident on the metal film and excited to generate the surface plasmons and are focused to generate the surface plasmon virtual probe, and the surface plasmon virtual probe and the scanning probe (401) are hybridized to form the surface plasmon field hybridization unit.

3. The needle-tip enhanced raman spectroscopy microscopic imaging device according to claim 2, wherein said metal film has a thickness of 40-50nm, and said objective lens (202) has a numerical aperture greater than 1.45.

4. The tip-enhanced Raman spectroscopy microscopic imaging apparatus according to claim 3, wherein a gap is formed between the scanning probe (401) and the metal film, and the gap is less than 10 nm.

5. The needle-tip enhanced Raman spectroscopy microscopic imaging apparatus according to claim 4, wherein the excitation light unit (10) comprises:

a laser element (101) for generating a laser beam of a predetermined wavelength;

and the polarizing element (102), the collimating element (103) and the vortex wave plate (104) are sequentially arranged between the laser element (101) and the objective lens (202) along the output direction of the optical path of the laser beam, and the laser beam is changed into radial polarized light through the polarizing element (102), the collimating element (103) and the vortex wave plate (104) and is incident to the objective lens (202).

6. The needle-tip enhanced Raman spectroscopy microscopic imaging apparatus according to claim 5, wherein said collimating element (103) is a lens group; and the radial polarized light is collimated by the lens group and then outputs parallel light.

7. The needle-tip-enhanced raman spectroscopy microscopic imaging apparatus according to claim 5, wherein said surface plasmon excitation unit (20) further comprises:

and the beam splitting element (201) is arranged between the beam incident end of the objective lens (202) and the beam emergent end of the vortex wave plate (104) and is used for transmitting the radial polarized light to the objective lens (202) and exciting and generating the surface plasmon on the metal film.

8. The needle-tip enhanced raman spectroscopy microscopic imaging apparatus according to claim 7, wherein said beam splitting element (201) is a beam splitter or a dichroic mirror.

9. The needle-tip enhanced raman spectroscopy microscopic imaging apparatus according to claim 7, wherein said detecting unit (50) comprises:

a filter element (501);

a spectrometer (502); and

a CCD image sensor (503);

the light filtering element (501), the spectrometer (502) and the CCD image sensor (503) are connected with the beam splitting element (201) through a horizontal straight line light path, Raman scattering light of a sample to be detected is coupled through the objective lens (202) to obtain coupled light and is reflected to the beam splitting element (201), the coupled light is transmitted through the light filtering element (501) and then enters the spectrometer (502) and the CCD image sensor (503), and the Raman spectrum of the sample to be detected is displayed and imaged according to a characteristic spectrum through the monitoring unit (60).

10. The tip-enhanced raman spectroscopy microscopic imaging apparatus according to any one of claims 1 to 9, wherein said scanning probe (401) is a probe plated with a metal film.

Images