CN106546334A - Space autofocusing confocal laser Raman spectroscopic detection method and apparatus - Google Patents

Abstract

The invention discloses a space self-adjusting laser confocal Raman spectrum detection method and device. The method and device introduce focusing telescopic technology and confocal technology in spectrum detection, and use a dichroic spectroscopic system to detect Rayleigh scattered light. Perform non-destructive separation with Raman scattered light, use the characteristic that the maximum value of the confocal response curve of the detector corresponds to the focus position precisely, and precisely control the telescopic system to automatically adjust the focus by finding the maximum value of the response, so that the excitation beam is automatically focused on the measured object At the same time, the spectral information of the focus position of the laser spot is obtained, and the spectral detection of the spatial auto-focus is realized, thereby forming a method and a device capable of realizing the spatial self-adjustable spectral detection of the sample. The invention has the characteristics of automatic focus adjustment and accurate fixed point, and at the same time expands the detection range and improves the spectrum detection sensitivity.

Description

Spatial self-adjusting laser confocal Raman spectroscopy detection method and device

technical field

The invention relates to the technical field of spatial optical imaging and spectral measurement, in particular to a method and device for spatial self-adjusting laser confocal Raman spectrum detection.

Background technique

Laser confocal Raman spectroscopy testing technology is a new technology that combines spatial imaging technology and Raman spectroscopy analysis technology. In the case of interference from surrounding substances, the structure and composition of the material components of the photographed sample can be obtained, providing better molecular "fingerprint" features. It can not only observe the Raman spectrum signals of different micro-regions in the same layer of the sample, but also observe the Raman signals of different layers of the sample space depth, and perform spatial scanning on the sample to be tested, so as to achieve the goal of carrying out the test without damaging the sample. The effect of map detection. Laser confocal Raman spectroscopy testing technology has been widely used in physics, chemistry, biomedicine, petrochemical industry, environmental science, material science, geology, Xing investigation, archaeology and jewelry identification due to its non-destructive spectral tomography capability and high resolution and other fields.

At present, the existing laser confocal Raman spectrometer uses a microscopic system, which limits the detectable range of the system; uses a three-dimensional mobile platform as a sample carrying platform, which limits the size and shape of the sample; uses weak Raman scattered light for positioning, reducing The fixed-focus sensitivity of the system is improved; during the long-term spectral detection process, the system is prone to drift due to environmental and other factors, resulting in defocus, which reduces the reliability of the system's long-term work; the system can only perform spectral detection, and the mode is single; during the measurement process It needs to be protected from light, and the working environment is restricted.

Contents of the invention

The invention provides a spatially self-adjusting laser confocal Raman spectrum detection method and device, aiming to solve the problems that the detection range of the existing confocal Raman spectrum detection technology is difficult to improve and the spectrum detection mode is single.

The technical solution of the present invention is: a spatial self-adjusting laser confocal Raman spectrum detection method, which uses the light collection ability of the telescopic system to separate the scattered light collected by the system into Rayleigh scattered light through a dichroic spectroscopic system and Raman scattered light; the Rayleigh scattered light enters the confocal detection system to adjust the focal position of the telescope and the focusing of the excitation light, and the Raman scattered light enters the Raman spectrum detection system for spectral detection, using the confocal The characteristic that the maximum value M of the curve corresponds to the position of the focal point O precisely, by finding the maximum value to precisely control the focus of the excitation beam on the sample, and at the same time obtain the spectral information of the focal point position of the excitation spot to realize automatic spectral detection in a large spatial range, the method includes Follow the steps below:

1) The excitation light is generated by the laser beam system, and after passing through the dichroic spectroscopic system and the telescopic system, it is irradiated on the sample to be tested, and the Rayleigh scattered light and the Raman scattered light carrying the spectral characteristics of the sample are excited;

2) Through the focusing mechanism, the response of the confocal detection system is maximized, the excitation beam is automatically focused on the sample, and the position information [α, β, l] of the sample is obtained at the same time;

3) Let the Rayleigh scattered light and Raman scattered light corresponding to the sample area to be measured pass through the telescopic system again, and be shaped into parallel light by the telescopic system and transmitted to the dichroic spectroscopic system. Scattered light and Raman scattered light are separated;

4) Part of the Rayleigh scattered light is transmitted by the dichroic spectroscopic system, reflected by the first spectroscopic system and enters the confocal detection system. Using the first detector in the confocal detection system, the intensity response I[ α, β, l], the focal position of the telescopic system can be determined, so as to complete the automatic focusing of the telescopic system and focus the excitation beam on the sample;

5) The Raman scattered light is transmitted through the dichroic spectroscopic system, and enters the Raman spectrum detection system through the first spectroscopic system, and the Raman scattering signal I(λ) carrying the characteristics of the measured sample is measured by the Raman spectrum detection system , the spectral test can be carried out, where λ is the wavelength;

6) Send I(λ) to the data processing module for data processing, so as to obtain spectral information I(λ) including the position of the corresponding area of the measured sample, and object position information [α, β, l];

7) Rotate the detection system to scan the space along the α and β directions, and the telescopic system scans and adjusts the focus along the l direction, and repeats the above steps to measure a group of n items corresponding to the focal position of the objective lens that contain position information [α, β, l ] and sequence measurement information of I(λ) [I(λ), α, β, l];

8) Use the position information [α, β, l] corresponding to the distinguishable area δn to find out the spectral information In(λ) value corresponding to the δn area, and then reconstruct the value according to the relationship with the space coordinates [α, β, l] Reflect the information In(αn, βn, ln, λn) of the three-dimensional structure and spectral characteristics of the micro-area δn of the measured object, which realizes the spectral detection and three-dimensional geometric position detection of the micro-area δmin;

9) The three-dimensional scale and spectral characteristics corresponding to the minimum resolvable region δmin are determined by the following formula:

That is, confocal Raman spectroscopy detection in a large spatial range is realized.

Preferably, the maximum value M of the confocal curve corresponds to the focal point O position of the telescopic system, where the focus spot size is the smallest and the detection area is the smallest, and other positions of the confocal curve correspond to the out-of-focus area of the telescopic system, before or after focus The focused spot size in the area increases with the amount of defocus. Taking advantage of this feature, the excitation beam can be precisely focused on the sample by adjusting the focusing mechanism of the telescopic system.

Preferably, the excitation light beam can be a polarized light beam: linearly polarized, circularly polarized or radially polarized light, and can also be a structured light beam generated by pupil filtering technology, which can be used in conjunction with polarization modulation technology to compress the size of the focused spot for measurement and improve System angular resolution.

A space self-adjusting laser confocal Raman spectrum detection device, including an excitation beam system, a telescopic focusing system, a dichroic spectroscopic system, a first spectroscopic system, a Raman spectroscopic detection system, a confocal detection system and data processing Module; wherein the excitation beam system and the telescopic focusing system are placed in the reflection direction of the dichroic spectroscopic system along the optical path; the first spectroscopic system is in the transmission direction of the dichroic spectroscopic system; the Raman spectrum detection system is located in the first spectroscopic system The transmission direction; the confocal detection system is located in the reflection direction of the first spectroscopic system; the data processing module is connected with the Raman spectrum detection system, the confocal detection system and the telescopic focusing system.

Preferably, the excitation beam system may further include a polarization modulator and a pupil filter. It is used to generate polarized light and spatially structured beams to improve the optical performance of the system.

Preferably, the pupil filter for compressing the excitation spot can be located between the polarization controller and the dichroic beam splitting system, or between the dichroic beam splitting system and the telescopic system.

Preferably, the excitation beam system can also be placed in the transmission direction of the dichroic light-splitting system, the telescopic system can be placed in the transmission direction of the dichroic light-splitting system, and the first light-splitting system can be placed in the reflection direction of the first dichroic light-splitting system.

Preferably, the Raman spectrum detection system can be an ordinary Raman spectrum detection system, comprising a fifth condenser placed in sequence along the optical path, a first spectrometer positioned at the focal point of the fifth condenser and a second detector positioned behind the first spectrometer, with It is used for the detection of the surface spectrum of the sample to be measured; it can also be a confocal Raman spectrum detection system, including the seventh condenser lens placed in sequence along the optical path, the third pinhole located at the focal position of the seventh condenser lens, and the third pinhole located behind the third pinhole The eighth condenser, the second spectrometer at the focal position of the eighth condenser and the third detector behind the second spectrometer are used to improve the signal-to-noise ratio and spatial resolution of the system and complete the spectral detection of the measured sample.

Preferably, the data processing module includes a confocal data processing module for processing position information, a data fusion module for processing position information and spectral information, and a data control module for controlling the focusing of the telescopic system.

The beneficial effect of the present invention is: a space self-adjusting laser confocal Raman spectrum detection method and device, which integrates telescopic technology, focusing technology, confocal technology and spectral detection technology, and uses the telescopic system to improve the light collection ability of the system , so that the system has a large spatial detection range; the precise positioning of the focus point of the confocal system greatly improves the spatial resolution of spectral detection; the system integrates confocal technology and focusing technology, which can realize automatic focus and automatic focus detection of samples; The system has three modes of spatial imaging, atlas imaging and spectral testing at the same time.

Description of drawings

With reference to the accompanying drawings, more objects, functions and advantages of the present invention will be clarified through the following description of the embodiments of the present invention, wherein:

Fig. 1 shows the laser confocal response curve of the present invention;

Fig. 2 shows the schematic diagram of the spatial self-adjusting laser confocal Raman spectrum detection method of the present invention;

Fig. 3 shows the schematic diagram of the spatial self-adjusting laser confocal Raman spectroscopy detection device of the present invention;

Fig. 4 shows the schematic diagram of Embodiment 1 of the spatial self-adjusting laser confocal Raman spectroscopy detection method and device of the present invention;

FIG. 5 shows a schematic diagram of Embodiment 2 of the spatial self-adjusting laser confocal Raman spectroscopy detection method and device of the present invention.

detailed description

The objects and functions of the present invention and methods for achieving the objects and functions will be clarified by referring to the exemplary embodiments. However, the present invention is not limited to the exemplary embodiments disclosed below; it can be implemented in various forms. The essence of the description is only to help those skilled in the relevant art comprehensively understand the specific details of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the laser confocal response curve of the present invention.

Fig. 2 is a schematic diagram of the spatial self-adjusting laser confocal Raman spectroscopy detection method of the present invention. As shown in Figure 2, the excitation beam system 600 generates excitation light, which is reflected by the dichroic spectroscopic system 900, and then focused on the sample 140 to be measured after being passed through the telephoto focusing system 100, and Rayleigh scattered light is excited on the sample. and the Raman scattered light carrying the spectral characteristics of the sample to be measured, the excited Raman scattered light and Rayleigh scattered light are collected back to the optical path by the system, after passing through the telescopic focusing system 100, and after being transmitted through the dichroic spectroscopic system 900 , the Raman scattered light and part of the Rayleigh scattered light are transmitted through the first spectroscopic system 150, part of the Rayleigh scattered light is reflected into the confocal detection system 170 for position detection, and the Raman scattered light is transmitted into the spectral detection system 220 for spectrum For detection, according to the confocal response curve, the data processing module controls the telephoto focusing mechanism to focus, so that the excitation light is focused on the sample, the confocal response curve is maximized, and the automatic focusing of the excitation beam is completed.

Fig. 3 is a schematic diagram of a spatial self-adjusting laser confocal Raman spectroscopy detection device of the present invention. As shown in FIG. 3 , the device includes an excitation beam system 600 sequentially placed along the optical path, a dichroic spectroscopic system 900 , a telephoto focusing system 100 , and a sample 140 to be measured, located at the first position in the transmission direction of the dichroic spectroscopic system 900 . The spectroscopic system 150, the spectral detection system 220 located in the transmission direction of the first spectroscopic system 150 and the confocal detection system 170 in the reflection direction also include a data processing module 340 connecting the spectral detection system 220, the confocal detection system 170 and the telescopic system 100 And computer control system 350.

Example 1

Fig. 4 is a schematic diagram of Embodiment 1 of the spatial self-adjusting laser confocal Raman spectroscopy detection method and device of the present invention.

As shown in Figure 4, a spatial self-adjusting laser confocal Raman spectroscopy detection method, the specific test method includes the following steps:

The laser 610 in the excitation beam system 600 generates excitation light, diverges and expands the beam through the first negative lens 620 , and collimates it into a parallel beam through the first condenser lens 630 .

The parallel light beam is reflected by the dichroic spectroscopic system 900, diverges after passing through the telescopic focusing mirror 110, and after being focused by the telescopic focusing mirror 130, focuses on the sample 140 to be tested, and excites Rayleigh scattered light and Raman scattered light carrying the spectral properties of the sample being measured.

The excited Raman scattered light and Rayleigh scattered light are collected back to the optical path by the telescopic light collecting mirror 130, after passing through the telescopic focusing mirror 110, the beam aperture is compressed, and after being transmitted through the dichroic spectroscopic system 900, the Raman scattered light and Part of the Rayleigh scattered light is transmitted and split by the first spectroscopic system 150 .

Part of the Rayleigh scattered light is reflected into the confocal detection system 170, converged by the fourth condenser lens 200, transmitted through the second pinhole 190, forms a light intensity response signal on the first detector 180, and is sent to the data processing module 340 , and then sent to the computer control system 350 after being processed. After the computer control system 350 processed, a control signal was formed and sent to the data processing module 340. The data processing module 340 generated a focus control signal and controlled the telephoto focus adjustment mechanism 120 to perform focus adjustment. , at the same time the signal of the first detector 180 will track and change to form a new control cycle, and this process continues until the first detector 180 has the maximum response, and the focusing mechanism 120 completes the focusing of the excitation light, at which time the Raman scattering The light is transmitted into the spectral detection system 220 for spectral detection.

Using the spatial self-adjusting laser confocal Raman spectrum detection device, the focusing mechanism 120 completes the focusing of the excitation light through the confocal detection response curve. At this time, the Raman scattered light is transmitted into the spectrum detection system 220 for spectrum detection, and the Raman scattering The light is converged by the fifth concentrator 240 and enters the first spectrometer 250, and the Raman scattered light is reflected by the incident slit 260, the plane mirror 270 and the first concave reflective concentrator 280 and reaches the spectral grating 300, and the light beam is diffracted by the spectral grating 300 and is The second concave reflective condenser 290 reflects and focuses to the second detector 230 . Due to the diffraction effect of the grating, the light of different wavelengths in the Raman spectrum is separated from each other, and what comes out of the spectrometer is the Raman spectrum of the sample.

During the measurement process, when the measured sample 140 is scanned in space, the first detector 180 in the confocal detection system 170 measures the intensity response that reflects the distance change of the measured sample 140 as I(α, β, l), and the The resulting intensity response I(α, β, l) is sent to the data processing module 340 for processing.

The Raman scattered light spectrum signal carrying the spectral information of the measured sample 140 detected by the second detector 230 in the Raman spectrum detection system 220 is I(λ), where λ is the wavelength;

Send I(λ), I(α, β, l) to the computer control system 350 for data processing, thereby obtaining a three-dimensional Measurement information I(α, β, l, λ).

The measured sample 140 is scanned along the α and β directions, the telephoto focusing mechanism 120 is scanned along the l direction, and the above steps are repeated to measure a group of n near the focal position of the corresponding objective lens that contains position information [α, β, 1] and I (λ) sequence measurement information [I(λ), α, β, l].

Use the position information [α, β, l] corresponding to the resolvable area δn to find out the spectral information In(λ) value corresponding to the δn area, and then reconstruct the reflected Measuring the information In(αn, βn, ln, λn) of the three-dimensional structure and spectral characteristics of the micro-area δn of the object, that is, realizing the spectral detection and three-dimensional geometric position detection of the micro-area δmin.

The three-dimensional scale and spectral characteristics corresponding to the minimum resolvable region δmin are determined by the following formula:

That is, the spatial self-adjusting laser confocal Raman spectroscopy detection is realized.

Micromap Imaging

I _σmin (α,β,l)=I _n (α,β,l) 3D shape imaging

I _σmin (α,β,l)=I _n (λ) Spectral measurement

It can be seen from Fig. 4 that the focus position of the excitation spot can be accurately captured through the maximum point of the response curve 210 of the confocal detection system 170, and the excitation spectrum corresponding to the focus position O is extracted from the measurement sequence data, that is, the Spectral detection and three-dimensional geometric position detection of micro area.

As shown in Figure 4, the spatially self-adjusting laser confocal Raman spectroscopy detection device includes a laser beam system 600 located in the reflection direction of the dichroic spectroscopic system 900, and a telephoto system placed in sequence along the optical path in the transmission direction of the dichroic spectroscopic system 900 The focusing mirror 110, the telescopic light collecting mirror 130 and the measured sample 140, the first spectroscopic system 150 located in the transmission direction of the dichroic spectroscopic system 900, the Raman spectrum detection system 220 located in the transmission direction of the first spectroscopic system 150, located in The confocal detection system 170 in the reflection direction of the first spectroscopic system, and the data processing module 340 connected with the confocal detection system 170, the Raman spectrum detection system 220 and the telescopic focusing mechanism 120, and the data processing module 340 connected through the serial port Computer control system 350 .

Wherein, the excitation beam generating system 600 is used to generate the excitation beam, including a laser 610 , a first negative lens 620 and a first condenser lens 630 sequentially placed along the optical path.

The Raman spectroscopy detection system 220 includes a fifth condenser lens 240 sequentially placed along the optical path, a first spectrometer 250 located at the focal point of the fifth condenser lens 240 and a second detector 230 located behind the first spectrometer 250 .

Wherein, the first spectrometer 250 includes an incident slit 260 , a plane mirror 270 , a first concave reflective condenser 280 , a spectral grating 300 and a second concave reflective condenser 290 sequentially placed along the optical path.

The confocal detection system 170 includes a fourth condenser lens 200 , a second pinhole 190 located at the focal point of the fourth condenser lens 200 , and a first detector 180 .

The data processing module 340 and the computer control system 350 are used to fuse and process the collected data and generate control signals.

Example 2

Fig. 5 is a schematic diagram of Embodiment 2 of the spatial self-adjusting laser confocal Raman spectroscopy detection method and device of the present invention. Compared with Embodiment 1, this embodiment is different in that: as shown in Figure 5, the excitation beam system 600 is placed in the transmission direction of the dichroic spectroscopic system 900, and the telephoto focusing system 100 is placed in the dichroic spectroscopic system 900 in the transmission direction, the first spectroscopic system 150 is placed in the reflection direction of the dichroic spectroscopic system 900 .

The specific embodiment of the present invention has been described above in conjunction with the accompanying drawings, but these descriptions can not be interpreted as limiting the scope of the present invention, the protection scope of the present invention is defined by the appended claims, any claims on the basis of the present invention The changes made are within the protection scope of the present invention.

Claims (9)

1. a kind of space autofocusing confocal laser Raman spectroscopic detection method, the method comprise the steps:

1) exciting light is produced by laser beam system, after dichroic optical system and telescopic system, is radiated at detected sample On product, and inspire Rayleigh scattering light and be loaded with the Raman diffused light of sample spectra characteristic；

2) by focus adjusting mechanism, make the response of confocal detection system maximum, complete excitation beam and be autofocusing on sample, while Obtain the positional information [α, β, l] of sample；

3) Rayleigh scattering light and Raman diffused light in correspondence sample region is made to again pass by telescopic system, and by telescopic system It is shaped to directional light and is transmitted through dichroic optical system, Jing dichroic optical systems is carried out to Rayleigh scattering light and Raman diffused light Separate；

4) part Rayleigh scattering light is transmitted by dichroic optical system, and the first beam splitting systems of Jing are reflected into confocal detection system, Using the first detector in confocal detection system, intensity response I [α, β, l] of reflection sample position information is measured, will be excited Light beam is focused on sample；

5) Raman diffused light Jing dichroic optical systems transmission, the first beam splitting systems of Jing are transmitted into Raman spectroscopic detection system, The Raman scattering signal I (λ) for being loaded with sample characteristic is measured using Raman spectroscopic detection system, wherein λ is wavelength；

6) I (λ) is sent to data processing module carries out data processing, so as to obtain comprising sample corresponding region position Spectral information I (λ) and object location information [α, β, l]；

7) rotation detection system, is carried out to space along α, and β scanning directions, telescopic system carry out focusing along l scanning directions, in repetition State the one group of n sequence measuring information [I comprising positional information [α, β, l] and I (λ) that step measures correspondence objective focus positions (λ), α, β, l]；

8) spectral information In (λ) value in correspondence δ n regions using the corresponding positional informationes [α, β, l] of distinguishable region δ n, is found out, Further according to information In of the relation with space coordinatess [α, β, l], reconstruct reflection measured object microcell δ n three dimensional structures and spectral characteristic (α n, β n, ln, λ n)；

9) three dimension scale and spectral characteristic of the minimum distinguishable region δ min of correspondence is determined by following formula：。

2. space autofocusing confocal laser Raman spectroscopic detection method according to claim 1, it is characterised in that confocal song Correspondence telescopic system focus O position at line maximum M, focused spot size is minimum herein, and the region of detection is minimum, confocal curves The out of focus region of other positions correspondence telescopic system, the focused spot size before Jiao or in defocused region is with defocusing amount increase Increase.

3. space autofocusing confocal laser Raman spectroscopic detection method according to claim 1, it is characterised in that exciting light Beam can be polarized beam：Linear polarization, circular polarization or radial polarisation light, can also be the structure light generated by pupil filtering technology Beam.

4. a kind of space autofocusing confocal laser Raman spectroscopic detection device, including excitation beam system, focusing system of looking in the distance, two To color beam splitting system, the first beam splitting system, Raman spectroscopic detection system, confocal detection system and data processing module；Wherein, swash Luminous beam system and focusing system of looking in the distance are placed sequentially in the reflection direction of dichroic optical system along light path；First beam splitting system In the transmission direction of dichroic optical system；Raman spectroscopic detection system is located at the transmission direction of the first beam splitting system；It is confocal Detection system is located at the reflection direction of the first beam splitting system；Data processing module and Raman spectroscopic detection system and confocal detection system System and focusing system connection of looking in the distance.

5. space autofocusing confocal laser Raman spectroscopic detection device according to claim 4, it is characterised in that exciting light Beam system can also include light polarization modulator and iris filter.

6. space autofocusing confocal laser Raman spectroscopic detection device according to claim 5, it is characterised in that for pressing Contracting excites the iris filter of hot spot to may be located between Polarization Controller and dichroic optical system, may be located on dichroic Between beam splitting system and telescopic system.

7. space autofocusing confocal laser Raman spectroscopic detection device according to claim 4, it is characterised in that exciting light Beam system can also be placed on the transmission direction of dichroic optical system, and telescopic system is placed on the transmission side of dichroic optical system To the first beam splitting system is placed on the reflection direction of dichroic optical system one.

8. space autofocusing confocal laser Raman spectroscopic detection device according to claim 4, it is characterised in that Raman light Spectrum detection system can be normal Raman spectroscopy detection system, including the 5th condenser lenss being sequentially placed along light path, positioned at the 5th First spectrogrph of condenser lenss focal position and the second detector after the first spectrogrph；Can also be confocal Raman spectra Detection system, including the 7th condenser lenss being sequentially placed along light path, positioned at the 3rd pin hole of the 7th condenser lenss focal position, is located at The 8th condenser lenss after 3rd pin hole, positioned at the second spectrogrph of the 8th condenser lenss focal position and after the second spectrogrph 3rd detector.

9. space autofocusing confocal laser Raman spectroscopic detection device according to claim 4, it is characterised in that at data Reason module includes confocal data processing module and data fusion module, also including data control block.