CN112414992A

CN112414992A - Raman spectrum excitation enhancement module

Info

Publication number: CN112414992A
Application number: CN202011272754.4A
Authority: CN
Inventors: 蒋霖坤; 马宁; 尧伟峰; 倪天瑞; 李立强; 陈加龙
Original assignee: Polaris Scientific Instruments Suzhou Co ltd; Suzhou Lingxi Precision Instrument Co ltd
Current assignee: Polaris Scientific Instruments Suzhou Co ltd; Suzhou Lingxi Precision Instrument Co ltd
Priority date: 2020-11-13
Filing date: 2020-11-13
Publication date: 2021-02-26

Abstract

The invention relates to a Raman spectrum excitation enhancement module, and belongs to the field of spectrometers. The invention is characterized in that: laser emitted by the laser is reflected by the first reflector and the second reflector in sequence, then is converged by the first lens, then is reflected by the third reflector, passes through the small hole of the first concave reflector and the first window sheet in sequence and then is focused on one focus of the detection point, and then is focused on the other focus of the detection point after being reflected by the second concave reflector. In this way, the laser light is reflected between the first and second concave mirrors a plurality of times, each time focusing on two focal points at the detection point. The interior of a chamber defined by the first window sheet, the second window sheet, the third window sheet and the fourth window sheet is liquid or gas to be detected. Therefore, Raman signals generated by exciting the sample by the laser at the two focuses can be enhanced by 50-100 times, the Rayleigh scattering of the laser is filtered by the optical filter after the Raman signals at the two focuses are collected by the second lens, and the Raman optical signals are converged in the entrance slit of the spectrometer.

Description

Raman spectrum excitation enhancement module

Technical Field

The invention relates to a spectral analysis instrument, in particular to a Raman spectrum excitation enhancement module.

Background

Raman spectroscopy (Raman spectroscopy), is a scattering spectrum. The Raman spectroscopy is an analysis method for analyzing a scattering spectrum with a wavelength different from that of incident light to obtain information on molecular vibration and rotation based on a Raman scattering effect found by indian scientists c.v. Raman (Raman), and is applied to molecular structure research. With the development of laser technology, raman spectroscopy is increasingly used to detect various substances. Since different molecules have specific vibration and rotation energy levels, when laser light of a certain wavelength scatters with a certain substance molecule, a part of laser photons exchange energy with the substance molecule. After the energy exchange occurs, the laser photon wavelength changes. Because different vibration and rotation energy levels correspond to the change of the laser photon wavelength one by one, the vibration or rotation energy level difference of the molecules can be determined by analyzing the laser spectrum after scattering, and the scattered molecules are separated out according to the energy level difference to be the substance. Just as the owner of a fingerprint can be determined by a fingerprint, the species of molecules can be determined by raman spectroscopy. At the same time, the concentration of the molecule can be determined by the intensity of the raman spectrum. In recent years, with the increasing maturity of optical devices such as lasers, detectors, optical filters and the like, raman spectrometers are rapidly developed at home and abroad.

However, raman spectroscopy is mostly limited to high purity solid and liquid detection. For gas and low concentration liquid detection, it is generally difficult to detect a valid signal due to the weak raman optical signal. Thus for raman detection of gases and low concentrations of liquids, enhancement of the raman signal is required, common enhancement means include: a surface-enhanced chip; reinforcing the nano gold and silver particles in the liquid; hollow optical fibers with silvered inner walls, and the like. However, the existing enhancement mode has the defects of generating fluorescence swamping Raman signals, poor repeatability of enhanced signals, high price, short service life and the like.

Disclosure of Invention

The invention provides a Raman spectrum excitation enhancement module which can be used for detecting liquid and gas and aims at solving the problems that the existing Raman spectrum enhancement mode can generate fluorescence submerging Raman signals, the enhancement signal repeatability is poor, the price is high, the service life is short and the like.

The technical scheme of the invention is as follows: the Raman spectrum excitation enhancing module mainly comprises two reflectors, exciting light is reflected for multiple times between the two reflectors and converged into two focuses at the center positions of the two reflectors, and Raman signals are enhanced by 50-100 times at the focuses.

The Raman spectrum excitation enhancement module core device comprises: the device comprises a laser, a first reflector, a second reflector, a first lens, a third reflector, a first concave reflector, a small hole, a second concave reflector, a detection point, a cavity, a first window sheet, a second window sheet, a third window sheet, a fourth window sheet, a second lens, an optical filter and a spectrometer. Laser emitted by the laser is reflected by the first reflector and the second reflector in sequence, then is converged by the first lens, then is reflected by the third reflector, passes through the small hole of the first concave reflector and the first window sheet in sequence and then is focused on one focus of the detection point, and then is focused on the other focus of the detection point after being reflected by the second concave reflector. In this way, the laser light is reflected between the first and second concave mirrors a plurality of times, each time focusing on two focal points at the detection point. The interior of a chamber defined by the first window sheet, the second window sheet, the third window sheet and the fourth window sheet is liquid or gas to be detected. Therefore, Raman signals generated by exciting the sample by the laser at the two focuses can be enhanced by 50-100 times, the Rayleigh scattering of the laser is filtered by the optical filter after the Raman signals at the two focuses are collected by the second lens, and the Raman optical signals are converged in the entrance slit of the spectrometer.

The invention has the beneficial effects that:

1. the laser is reflected for multiple times between the first concave reflector and the second concave reflector, each reflection focuses on two focuses at the detection point, and Raman signals generated by exciting a sample by the laser at the two focuses can be enhanced by 50-100 times;

2. additional fluorescence is not generated while the signal is enhanced, so that the Raman signal is prevented from being interfered;

3. the scheme is suitable for analyzing the ultralow concentration of various gases and liquids by using a Raman spectrum technology;

4. the scheme can also be used for laser spectrum enhancement of various liquid and gas samples.

Drawings

Fig. 1 is a schematic structural diagram of an apparatus according to a first embodiment of the raman spectroscopy excitation enhancing module of the present invention;

fig. 2 is a schematic structural diagram of an apparatus according to a second embodiment of the raman spectroscopy excitation enhancing module of the present invention.

Detailed Description

The invention is further described with reference to the following figures and examples.

A first embodiment of a raman spectroscopy module, the apparatus is shown in fig. 1: the laser device comprises a laser 1, a first reflector 2, a second reflector 3, a first lens 4, a third reflector 5, a first concave reflector 6, a small hole 7, a second concave reflector 8, a detection point 9, a chamber 10, a first window sheet 11, a second window sheet 12, a third window sheet 13, a fourth window sheet 14, a second lens 15, an optical filter 16 and a spectrometer 17. The laser output wavelengths can be 266nm, 405nm, 532nm, 785nm, 808nm, 1064nm, and the like. The emergent laser of the laser is reflected by the first reflector 2 and the second reflector 3 in sequence, is converged by the first lens 4, is reflected by the third reflector 5, sequentially passes through the small hole 7 of the first concave reflector 6 and the first window sheet 11, and then is focused on one focus of the detection point 9, and is reflected by the second concave reflector 8 and then is focused on the other focus of the detection point 9. The first reflector 2, the second reflector 3 and the third reflector 5 are all fixed on the two-dimensional mirror frame and used for finely adjusting angles. Thus, the laser light is reflected between the first concave mirror 6 and the second concave mirror 8 a plurality of times, each time focusing on two focal points at the detection point 9. Aiming at different laser excitation wavelengths, the two surfaces of the first window sheet 11, the second window sheet 12, the third window sheet 13 and the fourth window sheet 14 are respectively plated with a transmission increasing and reflecting film for the excitation wavelengths, and the transmissivity is more than 99.5%. The liquid or gas to be measured is arranged in the chamber 10 enclosed by the first window sheet 11, the second window sheet 12, the third window sheet 13 and the fourth window sheet 14. Therefore, Raman signals generated by exciting the sample by the laser at the two focuses can be enhanced by 50-100 times, the Raman signals at the two focuses are collected by the second lens 15, the Rayleigh scattering of the laser is filtered by the optical filter 16, and the Raman optical signals are converged in the entrance slit of the spectrometer 17. The optical filter is one or more than one optical filter, and an included angle of 2-3 degrees is formed between the optical filters.

The first embodiment of the raman spectroscopy module, the apparatus is shown in fig. 2: for the purpose of shaping the signal light and making the structure compact, a fiber bundle 18 is used for connection between the optical filter 16 and the spectrometer 17. The optical fiber bundle 18 is composed of one or more optical fibers, the numerical aperture of the optical fiber bundle needs to be matched with the numerical aperture of the spectrometer, the end face connected with the spectrometer is a row of optical fibers, and the end face of the optical fiber at the focusing position of the second lens 15 is a row of optical fibers or a plurality of rows of optical fibers.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A raman spectroscopy excitation enhancement module, the apparatus comprising: the device comprises a laser, a first reflector, a second reflector, a first lens, a third reflector, a first concave reflector, a small hole, a second concave reflector, a detection point, a chamber, a first window sheet, a second window sheet, a third window sheet, a fourth window sheet, a second lens, an optical filter and a spectrometer; the method is characterized in that: the laser is reflected by the first reflector and the second reflector in sequence, is converged by the first lens, is reflected by the third reflector, sequentially passes through the small hole of the first concave reflector and the first window sheet, and then is focused on one focus of the detection point, and is reflected by the second concave reflector, and then is focused on the other focus of the detection point, the laser is reflected for multiple times between the first concave reflector and the second concave reflector, each reflection is focused on two focuses of the detection point, the interior of a chamber enclosed by the first window sheet, the second window sheet, the third window sheet and the fourth window sheet is liquid or gas to be detected, Raman signals at the two focuses are collected by the second lens, the Rayleigh scattering of the laser is filtered by the optical filter, and the Raman optical signals are converged in the entrance slit of the spectrometer.

2. The raman spectral excitation enhancement module of claim 1, wherein: the first reflector, the second reflector and the third reflector are all fixed on a two-dimensional mirror frame which can finely adjust angles.

3. The raman spectral excitation enhancement module of claim 1, wherein: the first lens can move back and forth along the optical axis.

4. The raman spectral excitation enhancement module of claim 1, wherein: the two surfaces of the first window sheet, the second window sheet, the third window sheet and the fourth window sheet are respectively plated with a transmission and reflection increasing film corresponding to laser wavelength, and the transmissivity is more than 99%.

5. The raman spectral excitation enhancement module of claim 1, wherein: the edge of the first concave reflector is provided with a small hole with the diameter of 1-3mm, and laser passes through the small hole.

6. The raman spectral excitation enhancement module of claim 1, wherein: in order to achieve the purpose of convenient processing, the first concave reflector is replaced by a nonporous concave reflector, and laser passes through the edge of the nonporous concave reflector.

7. The raman spectral excitation enhancement module of claim 1, wherein: in order to achieve the purposes of Raman signal light shaping and size reduction, an optical fiber bundle is connected between the optical filter and the spectrometer.

8. The raman spectroscopy excitation enhancement module of claim 7, wherein: the optical fiber bundle consists of 1-100 optical fibers, the numerical aperture of the optical fiber bundle is matched with the numerical aperture of the spectrometer, the end surface connected with the spectrometer is a row of optical fibers, and the end surface of the optical fiber bundle at the focusing position of the second lens is 1-5 rows of optical fibers.