CN212059105U - High-resolution and high-sensitivity Raman spectrometer - Google Patents

Abstract

The utility model relates to a high resolution high sensitivity Raman spectrometer belongs to the spectrum appearance field. The utility model provides a cylindrical lens which adopts two or more pieces with certain inclination angles and is placed in front of a light-sensitive surface of a detector to compress the vertical height of a facula at a focus; a wide-spectrum high-sensitivity Raman spectrometer is provided, a concave reflecting mirror is adopted to replace a traditional lens to serve as a Raman light collecting element, a Raman light excitation and collection device is separated, a dichroic mirror is omitted, and the low wave number part of a Raman spectrum is expanded to be below 100cm < -1 >; the relationship between the focal length and the deflection angle of the two concave mirrors when the aberration is minimum is determined.

Description

High-resolution and high-sensitivity Raman spectrometer

Technical Field

The utility model relates to a raman spectroscopy appearance, in particular to high resolution high sensitivity raman spectroscopy appearance.

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 (man), 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.

The existing raman spectrometer generally uses a dichroic mirror with an inclination angle of 45 degrees to reflect laser and transmit raman light. Since dichroic mirrors generally do not transmit low wavenumber raman light in the 0-200cm-1 band, such raman spectrometers with dichroic mirrors are not capable of detecting substances with characteristic peaks in the 0-200cm-1 band. Especially for a raman spectrometer with a laser source in the ultraviolet band, such as a 266nm uv raman spectrometer, the dichroic mirror is not only expensive, but also generates fluorescence. In addition, for ultraviolet band laser, the double-cemented achromat lens cannot be used, and the chromatic aberration of the single lens and the aspheric lens is large, so that the sensitivity of the Raman spectrometer is low. Moreover, some detectors with small detection heights cannot completely receive the raman light, so that the sensitivity of the raman spectrometer is low. These existing technical bottlenecks limit the wide application of raman spectrometers.

SUMMERY OF THE UTILITY MODEL

The utility model discloses a to the present existing raman spectroscopy appearance be difficult to detect to the low wave number raman light of 0-200cm-1 wave band, ultraviolet raman spectroscopy appearance is because the lens colour difference causes sensitivity low greatly, and some detect highly less detector can not receive raman light scheduling problem completely, provide a wide spectrum high sensitivity raman spectroscopy appearance. The concave reflectors are adopted to replace lenses to be used as Raman light collecting elements, and the relation between the focal lengths and the inclination angles of the two concave reflectors when the aberration is minimum is provided. Two cylindrical lenses with certain inclination angles are placed in front of the light-sensitive surface of the detector, so that the sensitivity and the resolution of the Raman spectrometer are further improved. Thus, the low wavenumber part of the Raman spectral range is extended to 100cm-1 or less, and the sensitivity and resolution of the Raman spectrometer can be significantly improved.

The technical scheme of the utility model is that: a high resolution and high sensitivity Raman spectrometer.

The utility model discloses a device includes: the device comprises a slit, a first concave reflector, a light filter, a grating, a second concave reflector, a first cylindrical lens, a second cylindrical lens and a detector. The Raman light transmitted through the slit is collimated after being reflected by the first concave reflector, and then laser is filtered by one or more optical filters. The grating diffracts the Raman light with different wavelengths to different angles in the horizontal direction, and then the Raman light is reflected by the second concave reflector and focused on the photosensitive surface of the detector. The first cylindrical lens and the second cylindrical lens are positioned between the second concave reflecting mirror and the photosensitive surface of the detector. The detector may be a CCD, CMOS or other photosensitive element. The first cylindrical lens and the second cylindrical lens are each deflected by a small angle, typically 0-20 °, with respect to the photosensitive surface of the detector. The first cylindrical lens and the second cylindrical lens can be respectively a cylindrical concave lens and a cylindrical convex lens, can be two cylindrical convex lenses, and can also be replaced by one or more cylindrical lenses, and each cylindrical lens can be a convex lens or a concave lens, and respectively deflects a certain angle relative to the photosensitive surface of the detector.

For the part before the slit, the utility model has four embodiments.

In a first embodiment, an apparatus comprises: the laser device comprises a laser device, a laser focusing lens, a first small hole, a first concave reflector with a hole, a second small hole and a detection point. The laser emitted by the laser passes through the laser focusing lens and passes through the first small hole and the second band of the concave reflector with holesThe second small hole of the hole concave surface reflector is focused on a detection point, and the sample is placed at the detection point for Raman optical detection. Raman light generated at the detection point penetrates through the second small hole, is reflected and collimated by the first concave reflector with the hole, and is reflected and focused on the slit by the second concave reflector with the hole. The focal length and the deflection angle of the first concave reflector with holes and the second concave reflector with holes need to satisfy the following relations:

wherein f1 and f2 are focal lengths of the first holed concave reflector and the second holed concave reflector respectively, theta 1 is an included angle between a normal line of a central point of the first holed concave reflector and a connecting line of a central point and a detection point, and theta 2 is an included angle between a normal line of a central point of the second holed concave reflector and a connecting line of a central point of the slit. Meanwhile, the distance between the center of the first perforated concave reflector and the detection point is as follows: x1 is f1 cos (θ 1), and the center of the second concave perforated mirror is f2 cos (θ 2) away from the entrance slit x 2.

In a second embodiment, an apparatus comprises: the laser comprises a laser, a laser focusing lens, a first small hole, a first concave reflector with a hole, a second small hole, a detection point, a slit and a plane reflector. Laser emitted by the laser passes through the laser focusing lens, is reflected by the plane reflector, passes through the second small hole and is focused on the detection point, Raman light generated by the detection point passes through the second small hole, is reflected by the first perforated concave reflector and is collimated, and then passes through the first small hole and is focused on the slit after being reflected by the second perforated concave reflector. In a second embodiment, in the first embodiment, θ 1 is 0 and θ 2 is 0, and the first holed concave mirror and the second holed concave mirror are coaxial and do not deflect.

In a third embodiment, an apparatus comprises: the laser device, the laser focusing lens, the first aperture, the first concave reflector with aperture, the third concave reflector and the detection point. Laser emitted by the laser is focused on a detection point through the laser focusing lens, and Raman light generated by the detection point is collimated after being reflected by the first concave reflector with the hole and then focused on the slit through the third concave reflector. Focal length and deflection angle of first concave reflector with holes and third concave reflectorThe following relationships are required:

wherein f1 and f3 are focal lengths of the first perforated concave mirror and the third concave mirror, respectively, θ 1 is an angle between a normal of a center point of the first perforated concave mirror and a connecting line of the center point and the detection point, and θ 3 is an angle between a normal of a center point of the third concave mirror and a connecting line of the center point and the slit center point. Meanwhile, the distance between the center of the first perforated concave reflector and the detection point is as follows: x1 is f1 cos (θ 1), and the center of the third concave mirror is away from the entrance slit x3 is f3 cos (θ 3). The optical filter is positioned between the first concave reflecting mirror and the grating or between the first perforated concave reflecting mirror and the third concave reflecting mirror. The first cylindrical lens and the second cylindrical lens are positioned between the two concave reflectors and the detector or positioned between the third concave reflector and the slit.

In a fourth embodiment, an apparatus comprises: the laser device, the laser focusing lens, the detection point, the fourth concave reflecting mirror and the third concave reflecting mirror. Laser emitted by the laser is focused on a detection point through the laser focusing lens, and Raman light generated by the detection point is collimated after being reflected by the fourth concave reflector and then focused on the slit through the third concave reflector. The focal length and the deflection angle of the fourth concave reflector and the third concave reflector meet the following relations:

wherein f4 and f3 are focal lengths of the fourth concave reflector and the third concave reflector respectively, theta 4 is an included angle between a normal line of a central point of the fourth concave reflector and a connecting line of the central point and the detection point, and theta 3 is an included angle between a normal line of a central point of the third concave reflector and a connecting line of the central point and the slit central point. Meanwhile, the distance between the center of the fourth concave reflector and the detection point is as follows: x4 is f4 cos (θ 4), and the center of the third concave mirror is away from the entrance slit x3 is f3 cos (θ 3). The optical filter is located between the first concave reflector 9 and the grating 11, or between the fourth concave reflector and the third concave reflector.

The beneficial effects of the utility model reside in that:

1. a concave reflecting mirror is adopted to replace a traditional lens to serve as a Raman light collecting element, a Raman light excitation and collection device is separated, a dichroic mirror is omitted, and the low wave number part of a Raman spectrum is expanded to be below 100cm < -1 >.

2. When the minimum aberration is provided, the relationship between the focal lengths and the deflection angles of the two concave reflectors improves the sensitivity and the resolution of the Raman spectrometer.

3. Two cylindrical lenses with a certain inclination angle are placed in front of a light-sensitive surface of the detector or in front of the slit, so that the sensitivity and the resolution of the Raman spectrometer are improved.

Drawings

Fig. 1 is a schematic structural view of a device according to a first embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a second embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an apparatus according to a third embodiment of the present invention;

fig. 4 is a schematic structural view of a device according to a fourth embodiment of the present invention;

Detailed Description

The present invention will be further explained with reference to the accompanying drawings and examples.

The first embodiment of the present invention, the device is shown in fig. 1: the laser device comprises a laser device 1, a laser focusing lens 2, a first small hole 3, a first perforated concave reflector 4, a second perforated concave reflector 5, a second small hole 6, a detection point 7, a slit 8, a first concave reflector 9, an optical filter 10, a grating 11, a second concave reflector 12, a first cylindrical lens 13, a second cylindrical lens 14 and a detector 15. The laser 1 may be at different laser wavelengths, e.g. 213nm, 266nm, 532nm, 785nm, 1064nm, etc. The laser 1 can be either continuous laser or pulse laser, but generally requires the laser line width to be less than or equal to 0.2nm, and if the laser emitted from the laser 1 also contains other wave bands, a narrow band filter is required to be placed between the laser 1 and the laser focusing lens 2 to filter out the other wave bands. If the divergence angle of the laser emitted by the laser 1 is large, a group of laser collimation beam expanding lenses, generally a concave lens and a convex lens, or two convex lenses, are required to be inserted into the laser focusing lens 2, and the two lenses form a telescope system for collimating and expanding the laser. The laser focusing lens 2 may be a single lens, a double cemented lens or an aspheric lens. For laser light sources (such as 532nm, 785nm and 1064nm) in visible light and near infrared bands, the laser focusing lens 2 is generally a double cemented lens or a single lens; for a laser light source in the ultraviolet band (e.g. 213nm, 266nm), the laser focusing lens 2 is generally an aspheric lens or a single lens. The first holed concave reflector 4 is a concave mirror with a first small hole 3 with the diameter of about 10mm at the center. Similarly, the second concave reflector 5 with holes is a concave mirror with a second small hole 6 with a diameter of about 10 mm. The laser focused by the laser focusing lens 2 passes through the first small hole 3 and the second small hole 6 and then is focused on the detection point 7, and the sample to be detected is positioned at the detection point 7. For a solid sample, the detection point 7 needs to be located on the surface of the sample; for liquid or gas samples, the probe point 7 is located inside the liquid or gas sample to be measured in the container, since it is typically contained in a transparent container. For liquid or gas samples, the laser focusing lens 2 needs to have the same focal length as or close to the first concave mirror 9 to ensure the confocal condition, so that the laser focusing lens 2 needs to be fixed near the first small hole 3 before or after the first small hole. A window piece can be added between the second concave reflector 12 and the detection point, so that the whole machine is sealed. The Raman light generated at the detection point 7 is transmitted through the second small hole 6, is reflected by the first concave reflector with holes 4, is collimated, and is focused on the slit 8 through the second concave reflector with holes 5. Afterwards, the raman light is collimated after being reflected by the first concave reflecting mirror 9, then laser is filtered by one or more optical filters 10, then the raman light with different wavelengths is diffracted to different angles in the horizontal direction by the grating 11, and then the raman light is reflected by the second concave reflecting mirror 12 and focused on the photosensitive surface of the detector 15. The first cylindrical lens 13 and the second cylindrical lens 14 are located between the second concave reflecting mirror 12 and the photosensitive surface of the detector 15. The detector 15 may be a CCD, CMOS or other light sensitive element.

The focal length and the deflection angle of the first perforated concave reflector 4 and the second perforated concave reflector 5 need to satisfy the following relations:

wherein f1 and f2 are the focal lengths of the first holed concave reflector 4 and the second holed concave reflector 5 respectively, theta 1 is the angle between the normal of the central point of the first holed concave reflector 4 and the connecting line of the central point and the detection point 7, and theta 2 is the angle between the normal of the central point of the second holed concave reflector 5 and the connecting line of the central point of the slit 8. Meanwhile, the distance between the center of the first holed concave reflecting mirror 4 and the detection point 7 is as follows: x1 is f1 cos (θ 1), and the center of the second concave mirror with holes 5 is f2 cos (θ 2) away from the entrance slit x 2.

A first cylindrical lens 13 and a second cylindrical lens 14 are inserted between the second concave mirror 12 and the detector 15 in order to compress the light in the vertical direction without substantially changing the transmission of the light in the horizontal direction. The necessity of the first cylindrical lens 13 and the second cylindrical lens 14 is particularly obvious for the detector 15 with a smaller photosensitive height because the photosensitive heights of different detectors 15 in the vertical direction are different. Here, the first cylindrical lens 13 and the second cylindrical lens 14 are each deflected by a small angle, typically 0 to 10 °, with respect to the photosensitive surface of the detector 15. This has the advantage that the horizontal phase difference of the focus corresponding to each wavelength on the photosensitive surface of the detector 15 can be further eliminated, thereby improving the resolution of the spectrometer. The first cylindrical lens 13 and the second cylindrical lens 14 may be a cylindrical concave lens and a cylindrical convex lens, respectively, may be two cylindrical convex lenses, and may also be replaced by one or more cylindrical lenses, each cylindrical lens may be a convex lens or a concave lens, and each cylindrical lens is respectively deflected by a certain angle relative to the light-sensing surface of the detector 15, but it must be ensured that the whole cylindrical lens group is equivalent to one cylindrical convex lens.

The second embodiment of the present invention, the device is shown in fig. 2: the laser device comprises a laser device 1, a laser focusing lens 2, a first small hole 3, a first perforated concave reflector 4, a second perforated concave reflector 5, a second small hole 6, a detection point 7, a slit 8, a first concave reflector 9, an optical filter 10, a grating 11, a second concave reflector 12, a first cylindrical lens 13, a second cylindrical lens 14, a detector 15 and a plane reflector 16. Laser emitted by the laser 1 is reflected by the plane reflector 16 after passing through the laser focusing lens 2 and then focused on the detection point 7 after passing through the second small hole 6, Raman light generated by the detection point 7 passes through the second small hole 6 and then is reflected by the first holed concave reflector 4 and then is collimated, the Raman light is reflected by the second holed concave reflector 5 and then passes through the first small hole 3 and is focused on the slit 8, the optical filter 10 is positioned between the first concave reflector 9 and the grating 11, and the optical filter 10 can also be positioned between the slit 8 and the first concave reflector 9 or between the first holed concave reflector 4 and the slit 8. In a second embodiment, in the first embodiment, θ 1 is 0 and θ 2 is 0, and the first holed concave mirror and the second holed concave mirror are coaxial and do not deflect. The rest is the same as the first embodiment and is not repeated.

The third embodiment of the present invention, the device is shown in fig. 3: the laser device comprises a laser device 1, a laser focusing lens 2, a first small hole 3, a first holed concave reflector 4, a third concave reflector 16, a detection point 7, a slit 8, a first concave reflector 9, an optical filter 10, a grating 11, a second concave reflector 12, a first cylindrical lens 13, a second cylindrical lens 14 and a detector 15. The third embodiment differs from the first embodiment in that the second perforated concave mirror 5 is replaced with a third concave mirror 16. Laser emitted by the laser 1 is focused on a detection point 7 through the laser focusing lens 2, Raman light generated by the detection point 7 is collimated after being reflected by the first concave reflector 4 with holes, and then is focused on the slit 8 through the third concave reflector 16. The focal length and the deflection angle of the first concave reflector 4 with holes and the third concave reflector 16 need to satisfy the following relations:

wherein f1 and f3 are the focal lengths of the first holed concave reflector 4 and the third concave reflector 16 respectively, θ 1 is the angle between the normal of the center point of the first holed concave reflector 4 and the line connecting the center point with the detection point 7, and θ 3 is the angle between the normal of the center point of the third concave reflector 16 and the line connecting the center point with the center point of the slit 8. Meanwhile, the distance between the center of the first holed concave reflecting mirror 4 and the detection point 7 is as follows: x1 is f1 cos (θ 1), and the center of the third concave mirror 16 is away from the entrance slit x3 is f3 cos (θ 3). The filter 10 may be located between the first concave reflector 9 and the grating 11, or may be located between the first concave reflector and the gratingBetween the first perforated concave mirror 4 and the third concave mirror 16. The rest is the same as the first embodiment and is not repeated.

The fourth embodiment of the present invention, the device is shown in fig. 4: the laser device comprises a laser 1, a laser focusing lens 2, a detection point 7, a fourth concave reflector 17, a third concave reflector 16, a slit 8, a first concave reflector 9, an optical filter 10, a grating 11, a second concave reflector 12, a first cylindrical lens 13, a second cylindrical lens 14 and a detector 15. Laser emitted by the laser 1 is focused on the detection point 7 through the laser focusing lens 2, and Raman light generated by the detection point 7 is collimated after being reflected by the fourth concave reflecting mirror 17 and then focused on the slit 8 through the third concave reflecting mirror 16. The focal length and the deflection angle of the fourth concave reflector 17 and the third concave reflector 16 satisfy the following relations:

wherein f4 and f3 are the focal lengths of the fourth concave reflector 17 and the third concave reflector 16, respectively, θ 4 is the angle between the normal of the center point of the fourth concave reflector 17 and the line connecting the center point with the detection point 7, and θ 3 is the angle between the normal of the center point of the third concave reflector 16 and the line connecting the center point with the center point of the slit 8. Meanwhile, the distance between the center of the fourth concave reflecting mirror 17 and the detection point 7 is as follows: x4 is f4 cos (θ 4), and the center of the third concave mirror 16 is away from the entrance slit x3 is f3 cos (θ 3). The filter 10 may be located between the first concave mirror 9 and the grating 11, or between the fourth concave mirror 17 and the third concave mirror 16. The rest is the same as the first embodiment and is not repeated.

Above, only the preferred embodiment of the present invention is described, but not to limit the present invention in any form, and although the present invention has been disclosed with the preferred embodiment, but not to limit the present invention, any skilled person familiar with the art can make some changes or modifications to equivalent embodiments with equivalent changes within the technical scope of the present invention, but all the technical matters of the present invention do not depart from the technical scope of the present invention.

Claims (10)

1. A high resolution high sensitivity raman spectrometer, the apparatus comprising: slit, first concave surface speculum, grating, second concave surface speculum, first post lens, second post lens, detector, characterized by: the detection light penetrating through the slit is reflected and collimated by the first concave reflector, the Raman light with different wavelengths is diffracted to different angles in the horizontal direction by the grating, and the Raman light is focused on a photosensitive surface of the detector after being reflected by the second concave reflector, converged by the first cylindrical lens and the second cylindrical lens.

2. A high resolution high sensitivity raman spectrometer according to claim 1, wherein: the first cylindrical lens and the second cylindrical lens are respectively inclined at a certain angle.

3. A high resolution high sensitivity raman spectrometer according to claim 1, wherein: the first and second cylindrical lenses are replaced with one of the following cases: three cylindrical lenses inclined at a certain angle respectively; four cylindrical lenses inclined at a certain angle respectively.

4. A high resolution high sensitivity raman spectrometer according to claim 1, wherein: further comprising: the laser device comprises a laser device, a first small hole, a first holed concave reflector, a second small hole, a detection point and a slit, wherein emergent laser of the laser device passes through the first small hole of the first holed concave reflector and the second small hole of the second holed concave reflector and then focuses on the detection point, a sample is placed at the detection point to be subjected to Raman light detection, Raman light generated at the detection point penetrates through the second small hole and then is reflected and collimated by the first holed concave reflector, and then is reflected and focused on the slit through the second holed concave reflector.

5. The high resolution high sensitivity raman spectrometer of claim 4, wherein: the first hole concaveThe focal length and the deflection angle of the surface reflector and the second concave reflector with holes satisfy the following relations:

f1 and f2 are focal lengths of the first holed concave reflector and the second holed concave reflector respectively, θ 1 is an included angle between a normal of a center point of the first holed concave reflector and a connecting line of the center point and a detection point, θ 2 is an included angle between a normal of a center point of the second holed concave reflector and a connecting line of a center point of the slit, a distance x1 between the center of the first holed concave reflector and the detection point is f1 cos (θ 1), and a distance x2 between the center of the second holed concave reflector and the incident slit is f2 cos (θ 2).

6. The high resolution high sensitivity raman spectrometer of claim 4, wherein: a plane reflector is added, laser emitted by the laser device is reflected by the plane reflector after passing through the laser focusing lens, passes through the second small hole and is focused on the detection point, Raman light generated by the detection point passes through the second small hole, is reflected by the first perforated concave reflector and is collimated, and then passes through the first small hole after being reflected by the second perforated concave reflector and is focused on the slit.

7. The high resolution high sensitivity raman spectrometer of claim 4, wherein: the second concave reflector with holes is replaced by a third concave reflector, laser emitted by the laser is focused on a detection point, Raman light generated by the detection point is collimated after being reflected by the first concave reflector with holes, and then is focused on the slit through the third concave reflector.

8. A high resolution high sensitivity raman spectrometer according to claim 7, wherein: the focal length and the deflection angle of the first concave reflector with the holes and the third concave reflector meet the following relations:

wherein f1 and f3 are the first concave reflector with holes and the third concave reflectorThe reflector focal length is theta 1 which is an included angle formed by connecting a normal line of a center point of the first perforated concave reflector with a center point and a detection point, theta 3 which is an included angle formed by connecting a normal line of a center point of the third perforated concave reflector with the center point and a slit center point, the distance x1 between the center of the first perforated concave reflector and the detection point is f1 cos (theta 1), and the distance x3 between the center of the third perforated concave reflector and the incident slit is f3 cos (theta 3).

9. A high resolution high sensitivity raman spectrometer according to claim 7, wherein: and further replacing the first holed concave reflector with a fourth concave reflector, focusing laser emitted by the laser on a detection point, reflecting the Raman light generated by the detection point by the fourth concave reflector, collimating the Raman light, and focusing the Raman light on the slit by the third concave reflector.

10. A high resolution high sensitivity raman spectrometer according to claim 9, wherein: the focal length and the deflection angle of the fourth concave reflector and the third concave reflector meet the following relations:

wherein, f4, f3 are fourth concave mirror, third concave mirror focus respectively, and theta 4 is fourth concave mirror central point normal and central point and probing point line contained angle, theta 3 is third concave mirror central point normal and central point and slit central point line contained angle, fourth concave mirror center and probing point distance: x4 is f4 cos (θ 4), and the center of the third concave mirror is away from the entrance slit x3 is f3 cos (θ 3).

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