WO2021115062A1

WO2021115062A1 - Panoramic infrared spectral imaging system

Info

Publication number: WO2021115062A1
Application number: PCT/CN2020/129522
Authority: WO
Inventors: 焦国华; 罗栋; 陈巍; 周志盛; 刘鹏; 章逸舟; 陈良培; 谈宇光; 方浩华
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2019-12-10
Filing date: 2020-11-17
Publication date: 2021-06-17
Also published as: CN110793634A

Abstract

A panoramic infrared spectral imaging system, comprising an optical system, an infrared focal plane detector, a numerical control rotary table, a signal and image processing module, a display module, and a controller module. The optical system comprises a front tele-objective, a slit, a collimating lens, a reflecting grating, and an imaging lens. By adopting the reflecting grating and utilizing spectral imaging of the reflecting grating, high real-time performance is achieved, and various gas types can be quickly and accurately recognized; moreover, a numerical control rotary table is used, the field of view in the horizontal direction is expanded in a rotating mode, and panoramic detection in the horizontal direction can be achieved.

Description

A panoramic infrared spectrum imaging system

Technical field

The invention relates to the field of gas detection, in particular to a panoramic infrared spectrum imaging system.

Background technique

With the rapid development of petroleum, chemical industry, metallurgy, and electric power, there are more and more toxic, harmful, flammable and explosive gases that must be used or generated in the production process. Gas leakage detection has been a routine maintenance work for related companies in the above fields. , The research and development of gas leak detection equipment has important application significance for enterprise safety, personal safety and environmental protection. At present, some specific remote optical detection equipment have appeared in the world, which can be used to monitor in real time whether there are gas leaks in industrial sites such as chemical plants, refineries, and gas storage facilities. However, at present, such equipment usually can only detect a few specific gases, and the monitoring angle is too small and the equipment is expensive, so the cost performance is low.

In 2009, the Ministry of Housing and Urban-Rural Development of the People’s Republic of China formulated the "Petrochemical Flammable Gas and Production Safety" by detecting the concentration of leaked combustible gas or toxic gas and calling the police in time to prevent personal injury and fire and explosion accidents. Design Specification for Toxic Gas Detection and Alarm", in which the appendix lists as many as about one hundred common combustible or toxic gases. At present, there is no remote optical detection system on the market that can detect so many types of gas leaks.

Infrared imaging detection technology for gas leakage is mainly divided into active and passive according to whether there is a laser light source. In the application scenarios of remote detection of gas leakage, considering the attenuation of the laser light source in the air, a high-power laser radiation source is required. The resulting laser light source has a large volume and weight and poor safety, so it is mainly used at present Passive infrared imaging technology. Passive infrared imaging technology mainly includes thermal imaging technology and spectral imaging technology.

Among them, the thermal imaging technology mainly relies on collecting the radiation intensity of a certain infrared band of the target scene to achieve thermal imaging. Because the infrared characteristic absorption peaks of the measured gas are different, the lens and the infrared focal plane detector are switched between narrow bands with different cut-off frequencies. The filter or the long-pass filter method can realize the gas leak detection partly matched with the narrow band range of the filter. Typical products are the Second Slight series of gas imagers from Bertin Technology in France. It uses two broadband long-pass infrared filters, the reference filter and the active filter. The spectral area transmitted by the reference filter is not affected by the detected gas, while the spectral area transmitted by the active filter contains the infrared absorption band of the detected gas. In this way, the infrared collected by using these two filters The difference operation of the image can be used for the identification of the detected gas cloud.

As for the spectral imaging technology, according to the different principle of light splitting, it is mainly divided into dispersion type and interference type. A typical example is the FIRST series imaging spectrometer of Telops, Canada, which is based on the principle of Michelson interference to image gas leakage. It first obtains the interference fringe information of the observed target, and then performs inverse Fourier transform on the obtained information to reconstruct the spectral and spatial domain information of the target gas and scene. This product uses a refrigerated HgCdTe detector, which can image and detect a variety of gases.

In the existing technical solutions, for example, the Second Slight series gas imager of Bertin Technology Company of France has a fast response speed and very good real-time performance, but the type of gas it can detect strongly depends on the number of filters possessed on its runner. From the point of view of spectrum principle, the more the number of filters, the higher the spectral resolution. However, in actual products, the number of filters is often limited, usually around 6, so the types of gases that can be identified are very different. limited.

In addition, the imaging field of view of the Second Slight series gas imager is 30°×24°, and the imaging field of view of the FIRST series imaging spectrometer from Telops in Canada is 6.4°×5.1°. It can be seen that the field of view is not large and cannot be achieved. Panoramic automatic measurement on the horizontal plane.

Therefore, there is currently a need for a solution that can identify more gas types and can realize panoramic automatic measurement on the horizontal plane.

Technical solutions

Aiming at the defects in the prior art, the present invention proposes a panoramic infrared spectroscopy imaging system. By adopting a reflective grating and using the spectral imaging of the reflective grating, the real-time performance is high, and multiple gas types can be quickly and accurately identified; and With the CNC turntable, the horizontal field of view angle is extended by rotating mode, and horizontal panoramic detection can be realized.

Specifically, the present invention proposes the following specific embodiments:

The embodiment of the present invention proposes a panoramic infrared spectrum imaging system, including: an optical system, an infrared focal plane detector, a numerically controlled turntable, a signal and image processing module, a display module, and a controller module; the optical system includes: a front view Far objective lens, slit, collimating lens, reflection grating, imaging lens;

The front telephoto objective lens, the slit, the collimating lens, the reflection grating, the imaging lens, and the infrared focal plane detector are sequentially arranged along the incident light direction;

The optical system and the signal and image processing module are all arranged on the numerically controlled turntable;

The infrared focal plane detector and the infrared focal plane detector are connected to the signal and image processing module, so as to use the signal and image processing module to analyze the bands of different spectral bands acquired by the infrared focal plane detector. Image processing to obtain processed image data;

The controller module realizes a wireless network connection with the signal and image processing module, and is respectively connected with the display module and the numerical control turntable to control the rotation of the numerical control turntable, and to transfer the processed image data After processing, the infrared spectrum image data of the preset target scene is obtained and displayed on the display module and spectral matching is performed to determine whether there is a gas leak in the target scene, and to identify different types of gas.

In a specific embodiment, the reflection grating includes: a plane grating or a curved grating.

In a specific embodiment, when the optical system is placed vertically on the numerically controlled turntable, the optical system further includes: a mirror; wherein,

The reflecting mirror is arranged in front of the front telephoto objective lens in the direction of incident light.

In a specific embodiment, the optical lens of the front telephoto objective lens is made of zinc sulfide, zinc selenide, and germanium materials.

In a specific embodiment, the aperture of the optical lens of the front telephoto objective lens is greater than a preset value, and the focal length is greater than a preset threshold value.

In a specific embodiment, the infrared focal plane detector is a wide-band uncooled focal plane infrared detector, and the response wavelength of the infrared focal plane detector includes the 3-14 μm band.

In a specific embodiment, the reflection grating covers the 3-14 μm band corresponding to the splitting wavelength.

In a specific embodiment, the numerically controlled turntable is a single-axis numerically controlled turntable.

In a specific embodiment, the rotation range of the numerical control turntable is 360° in the horizontal direction.

In a specific embodiment, the "determining whether there is a gas leak in the target scene and identifying different types of gas" includes:

Compare the obtained infrared spectrum image data of the preset target scene with the absorption spectrum curves of different gases in the preset standard spectrum library to determine whether there is a gas leak in the target scene, and compare the gas in the target scene Perform category recognition.

Therefore, an embodiment of the present invention proposes a panoramic infrared spectroscopy imaging system, including: an optical system, an infrared focal plane detector, a numerically controlled turntable, a signal and image processing module, a display module, and a controller module; the optical system includes: A front telephoto objective lens, a slit, a collimating lens, a reflection grating, an imaging lens; the front telephoto objective lens, the slit, the collimating lens, the reflection grating, The imaging lens, the infrared focal plane detector; the optical system and the signal and image processing module are all set on the numerically controlled turntable; the infrared focal plane detector is connected to the signal and image processing module , To process the infrared spectrum image data acquired by the infrared focal plane detector through the signal and image processing module to obtain processed image data; the controller module and the signal and image processing module realize wireless Network connection, and respectively connected with the display module and the numerical control turntable to control the rotation of the numerical control turntable, and process the processed image data to obtain the infrared spectrum image data of the preset target scene The display module performs display to determine whether there is a gas leak in the target scene, and to identify different types of gas. By adopting the reflective grating and using the spectral imaging of the reflective grating, the real-time performance is very high, and various gas types can be quickly and accurately identified; and the numerical control turntable is used to rotate, which greatly expands the horizontal field of view. Achieve panoramic detection in the horizontal direction.

Description of the drawings

In order to explain the technical solutions of the embodiments of the present invention more clearly, the following will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative work.

FIG. 1 is a schematic structural diagram of a panoramic infrared spectrum imaging system proposed by an embodiment of the present invention;

2 is a schematic structural diagram of a panoramic infrared spectrum imaging system proposed by an embodiment of the present invention;

3 is a schematic diagram of the imaging system principle of a panoramic infrared spectrum imaging system proposed by an embodiment of the present invention;

4 is a schematic diagram of some gas absorption peaks in the HITRAN database involved in a panoramic infrared spectrum imaging system proposed by an embodiment of the present invention.

Embodiments of the present invention

Hereinafter, various embodiments of the present disclosure will be described more fully. The present disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of the present disclosure to the specific embodiments disclosed herein, but the present disclosure should be understood to cover those falling within the spirit and scope of the various embodiments of the present disclosure All adjustments, equivalents and/or alternatives.

The terms used in the various embodiments of the present disclosure are only used for the purpose of describing specific embodiments and are not intended to limit the various embodiments of the present disclosure. As used herein, the singular form is intended to also include the plural form, unless the context clearly dictates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meanings as commonly understood by those of ordinary skill in the art to which various embodiments of the present disclosure belong. The terms (such as those defined in commonly used dictionaries) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having idealized or overly formal meanings, Unless clearly defined in various embodiments of the present disclosure.

Example

The embodiment of the present invention discloses a panoramic infrared spectrum imaging system, as shown in FIG. 1 or 2, including: an optical system, an infrared focal plane detector, a numerically controlled turntable, a signal and image processing module, a display module, and a controller module; The optical system includes: front telephoto objective lens, slit, collimator lens, reflection grating, imaging lens;

The optical system, the infrared focal plane detector, and the signal and image processing module are all arranged on the numerically controlled turntable;

The infrared focal plane detector is connected to the signal and image processing module to process strip images of different spectral bands acquired by the infrared focal plane detector through the signal and image processing module to obtain processed Image data;

Specifically, the front telephoto objective lens can image the target in the field of view at the slit;

The image at the slit passes through a collimating lens and spectrally splitting through a reflection grating, and then passes through an imaging lens, so that it can be imaged at different positions of the infrared focal plane detector at different wavelengths.

All optical systems, signal and image processing modules in this part are located on the single-axis CNC turntable, and will be rotated by the single-axis CNC turntable after the system is started. The core of the signal and image processing module can be an FPGA (Field Programmable Gate Array) chip, which uses wireless data transmission with the lower fixed controller module to detect the infrared focal plane in real time The infrared spectrum image data obtained by the detector is transmitted to the controller module.

The controller module controls the single-axis CNC turntable. After one rotation, the infrared spectrum image data of the target panorama in the horizontal direction is obtained through wireless data transmission. This data contains the horizontal panorama infrared spectrum image under different bands, and can be used by the display module. Display and compare with the absorption spectrum curves of different gases in the preset standard spectrum library to determine whether there is a gas leak in the target scene, and to identify different types of gases.

Regarding the reflection grating, take a plane grating as an example. A plane grating is an element formed by scoring a series of notches on a high-precision plane. This series of notches can produce a diffraction effect on incident light. According to the principle of light diffraction, the sine value of the diffraction angle is proportional to the wavelength, so it contains different wavelength components. After the incident light with the same incident angle is reflected by the plane grating, the light of different wavelength components will have different exit angles. To achieve the purpose of light splitting.

Regardless of whether it is a flat grating or a curved grating, the principle of its light splitting effect remains unchanged, and the curved grating can be selected in a targeted manner, so that whether it is a flat grating or a curved grating, the corresponding wavelength region remains unchanged.

The schematic diagram of the principle of the spectral imaging system of the reflection grating is shown in Figure 3. The incident light is condensed by the front telephoto objective lens and then passes through the vertical slits, and then passes through the collimating lens to generate parallel light. The parallel light then passes through the reflective grating to produce diffracted light, and finally is focused on the focal plane of the infrared focal plane detector through the imaging lens to form striped images of different spectral bands.

The information in the horizontal direction obtained by the infrared focal plane detector is the spectral information, which represents different wavelength bands; the information obtained in the vertical direction is the spatial information, which represents the imaging of the vertical strip-shaped target object surface. The spectral resolution of the panoramic infrared spectral imaging system will be determined by the horizontal pixel size of the infrared focal plane detector.

With the rotation of the numerical control turntable, the different frame rate images acquired by the panoramic infrared spectrum imaging system are equivalent to horizontal scanning and imaging of the target surface.

Specifically, in this solution, the optical system can be placed horizontally on the CNC turntable, so that the reflector can be omitted, and in order to save space, the entire optical system value can also be placed on the CNC turntable; if the optical system is placed vertically When on the numerically controlled turntable, in this solution, a reflector is set before the front telescope objective in the direction of the incident light, so that the reflector and the front telescope are sequentially arranged along the direction of the incident light. The objective lens, the slit, the collimating lens, the reflection grating, the imaging lens, and the infrared focal plane detector realize detection.

Optical lenses made of zinc sulfide, zinc selenide, and germanium materials (such as germanium glass) can be used. Optical lenses made of this material have high transmittance to the medium-wave and long-wave infrared bands.

In addition, in order to ensure more accurate measurement, the optical lens of the front telephoto objective adopts a large aperture and a large focal length.

In a specific embodiment, in order to avoid a large device volume and excessive power consumption, the infrared focal plane detector is selected as a wide-band uncooled focal plane infrared detector, which makes the overall device small, easy to operate and Maintenance and lower overall power consumption. The response wavelength of the infrared focal plane detector includes the 3-14 μm band.

Specifically, in this solution, an uncooled infrared focal plane detector is used, and its wide band only needs to cover the 3-14 μm band.

Specifically, in gas detection, since most of the absorption peaks of heteronuclear diatoms and polyatomic molecules are located in the 3-14 μm infrared band, the 3-14 μm band is called the fingerprint region of gas molecules. The corresponding spectral ranges of medium-wave infrared detectors and long-wave infrared detectors are 3～5μm and 8～14μm, respectively. The atmospheric transmittance of infrared radiation in these two spectral ranges is relatively high, which can avoid the influence of the atmosphere on imaging to a large extent. It is the atmospheric infrared transmission window.

Infrared imaging of gas leakage is to use medium-wave or long-wave infrared focal plane detectors to image the infrared 3～14μm band. According to the characteristics of dynamic diffusion during gas leakage and the absorption characteristics of gas molecules in this infrared band, the gas leakage point and Gas diffusion area.

Therefore, the response wavelength of the infrared focal plane detector is required to include the 3-14 μm band. Correspondingly, the corresponding split wavelength of the reflection grating covers the 3-14 μm band, so as to cover the absorption characteristic peak of the gas to be detected.

Specifically, the controller module can be used to control the rotation speed of the numerical control turntable, and the controller module can be used to obtain the real-time deflection angle of the numerical control turntable. In the actual application process, the panoramic infrared spectrum imaging system in this solution is generally more than 1 to 2km away from the measured scene, so the panoramic infrared spectrum imaging system in this solution does not need to have a large vertical direction. The angle of view (that is, no need to use a two-axis turntable), therefore, a single-axis CNC turntable can be used.

In a specific embodiment, in order to ensure panoramic measurement, the rotation range of the numerically controlled turntable is 360° in the horizontal direction.

Specifically, the process of judging whether there is a gas leak in the target scene and identifying different types of gas, that is, the process of processing spectral images, is mainly based on the spectral matching method to determine whether there is a gas leak in the target scene, and The type of leaked gas is judged.

The spectral matching method refers to comparing the image spectrum obtained by the infrared focal plane detector with the absorption spectrum curves of different gases in the HITRAN infrared spectrum library to perform spectral matching, thereby determining the gas category. Figure 4 shows a schematic diagram of the absorption peaks of some gases in the 3-12μm band. The data comes from the HITRAN database. The HITRAN database contains the par format spectral data of dozens of common gas molecules under different environmental conditions, which is very suitable for use as a standard database for comparison. It is also possible to use other databases storing absorption spectrum curves of different gases as a standard spectrum library for comparison, and it is not limited to the above one.

Therefore, in general, the uncooled infrared focal plane detector is used in this solution, so the overall device volume can be small. In addition, the reflective grating-type spectral imaging technology is adopted, which has high real-time performance and can quickly detect a variety of gas types. Accurate identification, also uses the single-axis CNC turntable's rotation mode, which greatly expands the horizontal field of view, and can realize horizontal panoramic detection.

Therefore, an embodiment of the present invention proposes a panoramic infrared spectroscopy imaging system, including: an optical system, an infrared focal plane detector, a numerically controlled turntable, a signal and image processing module, a display module, and a controller module; the optical system includes: A front telephoto objective lens, a slit, a collimating lens, a reflection grating, an imaging lens; the front telephoto objective lens, the slit, the collimating lens, the reflection grating, The imaging lens, the infrared focal plane detector; the optical system and the signal and image processing module are all set on the numerically controlled turntable; the infrared focal plane detector is connected to the signal and image processing module , To process the infrared spectrum image data acquired by the infrared focal plane detector through the signal and image processing module to obtain processed image data; the controller module and the signal and image processing module realize wireless Network connection, and respectively connected with the display module and the numerical control turntable to control the rotation of the numerical control turntable, and process the processed image data to obtain the infrared spectrum image data of the preset target scene The display module performs display to determine whether there is a gas leak in the target scene, and to identify different types of gas. By adopting the reflective grating and using the spectral imaging of the reflective grating, the real-time performance is very high, and multiple gas types can be quickly and accurately identified. In addition, a numerical control turntable is used to expand the horizontal field of view in a rotating manner, which can realize horizontal panoramic detection.

Those skilled in the art can understand that the accompanying drawings are only schematic diagrams of preferred implementation scenarios, and the modules or processes in the accompanying drawings are not necessarily necessary for implementing the present invention.

Those skilled in the art can understand that the modules in the device in the implementation scenario can be distributed in the device in the implementation scenario according to the description of the implementation scenario, or can be changed to be located in one or more devices different from the implementation scenario. The modules of the above implementation scenarios can be combined into one module or further divided into multiple sub-modules.

The above serial numbers of the present invention are only for description, and do not represent the pros and cons of implementation scenarios.

What has been disclosed above are only a few specific implementation scenarios of the present invention, but the present invention is not limited to these, and any changes that can be thought of by those skilled in the art should fall into the protection scope of the present invention.

Claims

A panoramic infrared spectrum imaging system, which is characterized by comprising: an optical system, an infrared focal plane detector, a numerically controlled turntable, a signal and image processing module, a display module, and a controller module; the optical system includes: a front telephoto objective lens , Slit, collimating lens, reflective grating, imaging lens;

The front telephoto objective lens, the slit, the collimating lens, the reflection grating, the imaging lens, and the infrared focal plane detector are sequentially arranged along the incident light direction;

The optical system, the infrared focal plane detector, and the signal and image processing module are all arranged on the numerically controlled turntable;

The infrared focal plane detector is connected to the signal and image processing module to process the strip images of different spectral bands acquired by the infrared focal plane detector through the signal and image processing module to obtain the processed image Image data;

The controller module realizes a wireless network connection with the signal and image processing module, and is respectively connected with the display module and the numerical control turntable to control the rotation of the numerical control turntable, and to transfer the processed image data After processing, the infrared spectrum image data of the preset target scene is obtained and displayed on the display module and spectral matching is performed to determine whether there is a gas leak in the target scene, and to identify different types of gas.
A panoramic infrared spectral imaging system according to claim 1, wherein the reflection grating comprises: a plane grating or a curved grating.
The panoramic infrared spectrum imaging system of claim 1, wherein when the optical system is placed vertically on the numerically controlled turntable, the optical system further comprises: a mirror; wherein,

The reflecting mirror is arranged in front of the front telephoto objective lens in the direction of incident light.
The panoramic infrared spectrum imaging system of claim 1, wherein the optical lens of the front telephoto objective lens is made of zinc sulfide, zinc selenide, and germanium materials.
The panoramic infrared spectrum imaging system of claim 1 or 4, wherein the aperture of the optical lens of the front telephoto objective lens is greater than a preset value, and the focal length is greater than a preset threshold value.
A panoramic infrared spectral imaging system according to claim 1 or 4, wherein the infrared focal plane detector is a wide-band uncooled focal plane infrared detector, and the response wavelength of the infrared focal plane detector is Contains 3～14μm band.
A panoramic infrared spectral imaging system according to claim 1, wherein said reflection grating corresponds to a split wavelength covering the 3-14 μm band.
The panoramic infrared spectrum imaging system of claim 1, wherein:

The numerical control turntable is a single-axis numerical control turntable.
A panoramic infrared spectrum imaging system according to claim 1 or 8, wherein the rotation range of the numerically controlled turntable is 360° in the horizontal direction.
The panoramic infrared spectroscopy imaging system according to claim 1, wherein the "determining whether there is a gas leak in the target scene and identifying different types of gas" includes:

Compare the obtained infrared spectrum image data of the preset target scene with the absorption spectrum curves of different gases in the preset standard spectrum library to determine whether there is a gas leak in the target scene, and compare the gas in the target scene Perform category recognition.