A portable infrared spectrometer suitable for VOCs detection

Abstract

The present invention relates to a portable infrared spectrometer, and in particular to a portable infrared spectrometer suitable for VOCs detection. It comprises a support rod and an angle mirror 1 and an angle mirror 2 arranged at both ends of the support rod, a rotating bearing is arranged in the middle of the support rod, and the rotating bearing can be driven to rotate by a motor to drive the support rod to rotate; an end reflector 1 and an oblique reflector 1 are arranged below the angle mirror 1; an end reflector 2 and an oblique reflector 2 are arranged below the angle mirror 2; a beam splitter / compensator is vertically arranged between the oblique reflector 1 and the oblique reflector 2, a laser emitting device is arranged on one side of the beam splitter / compensator, and a long optical path absorption device is arranged on the other side of the beam splitter / compensator. Therefore, the present invention has the following advantages: 1. The mechanical structure is stable and suitable for portable detection occasions. 2. A structure in which the optical path is equal to 8 times the mechanical stroke is realized, so that under the same spectral resolution, the mechanical stroke is greatly reduced, making the spectral scanning more stable.

Description

Technical Field

[0001] The invention relates to a portable infrared spectrometer, in particular to a portable infrared spectrometer suitable for VOCs detection. Background Art

[0002] The portable structure of the Fourier infrared spectrometer used in the existing VOcs detection technology basically adopts the Michelson type or its modified optical interference structure, which has the disadvantage of poor structural stability, especially when the measurement optical resolution requirement is high, and the optical mechanical stroke of the interferometer itself is small, resulting in a long movement distance of the interference scanning mirror. For portable instruments, long-distance interference scanning has a significant impact on spectral stability, which can easily lead to spectral distortion and reduce the accuracy of the measurement results. Summary of the invention

[0003] The above technical problems of the present invention are mainly solved by the following technical solutions:

[0004] A portable infrared spectrometer suitable for VOCs detection is characterized in that it includes a support rod and corner mirror 1 and corner mirror 2 arranged at both ends of the support rod, a rotating bearing is arranged in the middle of the support rod and can be driven by a motor to rotate the rotating bearing to drive the support rod to rotate; an end reflector 1 and an oblique reflector 1 are arranged below the corner mirror 1; an end reflector 2 and an oblique reflector 2 are arranged below the corner mirror 2; a beam splitter / compensator is vertically arranged between the oblique reflector 1 and the oblique reflector 2, a laser emitting device is arranged on one side of the beam splitter / compensator, and a long optical path absorption device is arranged on the other side of the beam splitter / compensator.

[0005] The invention is creative in that:

[0006] 1. A rotary bearing 3 is driven by a rotary motor and a rotary spring, so that the support rod on which the corner mirrors 1 and 2 are mounted swings to achieve a scanning effect.

[0007] 2. The introduction of two end mirrors magnifies the optical path difference by 1 times compared with the Rocksolid series (the optical path difference is approximately 4Rθ), allowing the support rod to obtain higher spectral resolution at the same swing angle (the spectral resolution is approximately the inverse of the optical path difference), while eliminating the beam shearing effect caused by a slight lateral shift of the corner mirror end point.

[0008] 3. Two oblique reflectors are introduced to make the infrared light beam form an interference beam at the beam splitter / compensator 6, and then directly pass through the long optical path absorption cell 10, so that the infrared light beam absorbs the VOCs component and generates an absorption spectrum signal, which is captured by the detector.

[0009] In the above-mentioned portable infrared spectrometer suitable for VOCs detection, the laser emitting device includes a laser and a parabolic mirror 1. The laser beam is emitted to the beam splitter / compensator through the parabolic mirror 1. The infrared light of the infrared light source can be reflected to the beam splitter / compensator through the parabolic mirror 1. A laser signal detector is provided between the parabolic mirror 1 and the beam splitter / compensator.

[0010] In the above-mentioned portable infrared spectrometer suitable for VOCs detection, the long optical path absorption device includes a parabolic mirror 2 and a long optical path absorption cell arranged between the parabolic mirror 2 and the beam splitter / compensator. The infrared light can enter the infrared signal detector arranged below the parabolic mirror 2 after being reflected by the parabolic mirror 2.

[0011] In the above-mentioned portable infrared spectrometer suitable for VOCs detection, the long optical path absorption cell model is C10, and the equivalent absorption optical path is 10 meters.

[0012] The present invention improves the portable structure of the Fourier infrared spectrometer used in the traditional VOCs detection technology and proposes an interference structure with 8 times the mechanical stroke. While obtaining the same spectral resolution, the interference mechanical stroke is smaller. At the same time, the structure has excellent anti-vibration ability and is particularly suitable for portable on-site VOCs detection.

[0013] Therefore, the present invention has the following advantages: 1. The mechanical structure is stable and suitable for portable detection occasions. 2. The structure that the optical path is equal to 8 times the mechanical stroke is realized, so that under the same spectral resolution, the mechanical stroke is greatly reduced, making the spectral scanning more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the main structure of the present invention.

[0015] Figure 2 Schematic diagram of the optical path of the present invention. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further specifically described below through embodiments and in conjunction with the accompanying drawings. In the drawings, support rod 1, corner mirror 1 2-1, corner mirror 2 2-2, rotating bearing 3, end reflector 1 4-1, end reflector 2 4-2, oblique reflector 1 5-1, oblique reflector 2 5-2, beam splitter / compensator 6, infrared light source 7, parabolic mirror 1 8-1, parabolic mirror 2 8-2, infrared signal detector 9, long optical path absorption cell 10, laser 11, laser signal detector 12.

[0017] Example:

[0018] The present invention includes a support rod, a first corner mirror and a second corner mirror provided at both ends of the support rod. A rotating bearing is provided in the middle of the support rod, and the rotating bearing can be driven by a motor to rotate, thereby driving the support rod to rotate; a first end mirror and a first inclined mirror are respectively provided below the first corner mirror; a second end mirror and a second inclined mirror are respectively provided below the second corner mirror; a beam splitter / compensator is vertically provided between the first inclined mirror and the second inclined mirror, a laser emission device is provided beside the beam splitter / compensator, and a long optical path absorption device is provided beside the beam splitter / compensator on the other side.

[0019] The laser emission device includes a laser and a first parabolic mirror. The laser beam is incident on the beam splitter / compensator through the first parabolic mirror, and the infrared light of the infrared light source can be reflected by the first parabolic mirror onto the beam splitter / compensator; a laser signal detector is provided between the first parabolic mirror and the beam splitter / compensator.

[0020] The long optical path absorption device includes a second parabolic mirror and a long optical path absorption cell provided between the second parabolic mirror and the beam splitter / compensator. The infrared light can be reflected by the second parabolic mirror and then enter an infrared signal detector provided below the second parabolic mirror. The model of the long optical path absorption cell is C10, and the equivalent absorption optical path is 10 meters.

[0021] During actual operation, a rotating bearing 3 is driven by a rotary motor and a rotary spring, so that the support rod carrying the first corner mirror and the second corner mirror swings, generating a spectral scanning effect. The equivalent optical path is as Figure 2 , Figure 2 In, the double-dot dash line is the rotation circular contour of the support rod, the short dashed line is the mechanical position of the support rod when it rotates through an angle θ. The long dashed line is the optical path of the support rod when it rotates through an angle θ. R is the equivalent radius of the support rod, θ is the swing angle of the support rod, and d is the distance between the incident light and the retroreflected light of the corner mirror.

[0022] The optical path difference generated during the swinging process of the support rod is 8Rθ + 4d(1 / cosθ - 1). Usually, d << R, and the spectral measurement data will be selected within a small range of the swing angle θ. At this time, the optical path can be approximately 8Rθ. Due to the introduction of the two end mirrors 4-1 and 4-2, the optical path difference is doubled compared to the Rocksolid series (the optical path difference is approximately 4Rθ), allowing the support rod to obtain a higher spectral resolution (the spectral resolution is approximately the reciprocal of the optical path difference) at the same swing angle, and at the same time eliminating the beam shear effect caused by the slight lateral displacement of the corner mirror end point.

[0023] Due to the above optical properties and the introduction of the rotary spring, this structure has excellent anti-vibration ability and is particularly suitable for portable on-site VOCs detection instruments.

[0024] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0025] Although this article uses more terms such as support rod 1, angle mirror 1 2-1, angle mirror 2 2-2, rotating bearing 3, end reflector 1 4-1, end reflector 2 4-2, oblique reflector 1 5-1, oblique reflector 2 5-2, beam splitter / compensator 6, infrared light source 7, parabolic mirror 1 8-1, parabolic mirror 2 8-2, infrared signal detector 9, long optical path absorption cell 10, laser 11, laser signal detector 12, etc., it does not exclude the possibility of using other terms. The use of these terms is only for more convenient description and explanation of the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. A portable infrared spectrometer suitable for VOCs detection, characterized in that: It includes a support rod, and a first corner mirror and a second corner mirror arranged at both ends of the support rod. A rotating bearing is provided in the middle of the support rod, and the rotating bearing can be driven by a motor to rotate, thereby driving the support rod to rotate; a first end mirror and a first inclined mirror are respectively arranged below the first corner mirror; a second end mirror and a second inclined mirror are respectively arranged below the second corner mirror; a beam splitter / compensator is vertically arranged between the first inclined mirror and the second inclined mirror, a laser emission device is arranged beside the beam splitter / compensator, and a long optical path absorption device is arranged beside the beam splitter / compensator on the other side. The rotating bearing is driven by a rotary motor and a rotary spring, so that the support rod mounted with the first corner mirror and the second corner mirror swings, generating a spectral scanning effect. The optical path difference generated during the swinging process of the support rod is 8Rθ + 4d(1 / cosθ - 1), where d << R, R is the equivalent radius of the support rod, θ is the swinging angle of the support rod, and d is the distance between the incident light and the retroreflected light of the corner mirror.

2. A portable infrared spectrometer suitable for VOCs detection according to claim 1, characterized in that: The laser emission device includes a laser and a first parabolic mirror. The laser beam is incident on the beam splitter / compensator through the first parabolic mirror, and the infrared light of the infrared light source can be reflected by the first parabolic mirror and incident on the beam splitter / compensator; a laser signal detector is arranged between the first parabolic mirror and the beam splitter / compensator.

3. A portable infrared spectrometer suitable for VOCs detection according to claim 1, characterized in that: The long optical path absorption device includes a second parabolic mirror and a long optical path absorption cell arranged between the second parabolic mirror and the beam splitter / compensator. The infrared light can be reflected by the second parabolic mirror and then enter the infrared signal detector arranged below the second parabolic mirror.

4. A portable infrared spectrometer suitable for VOCs detection according to claim 1, characterized in that: The model of the long optical path absorption cell is C10, and the equivalent absorption optical path is 10 meters.

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