Gas detection imaging spectrometer based on DMD and transmission-type grating

Abstract

The invention discloses a gas detection imaging spectrometer based on a DMD and a transmission-type grating, the gas detection imaging spectrometer comprises a gas detection imaging spectrometer body, a base, an angle seat and a camera interface ring, the gas detection imaging spectrometer body solves the problem of detection errors caused by unstable ambient light, provides a reliable basis for gas characteristic absorption signal extraction, and improves the detection accuracy. The DMD virtual slit is combined with the transmission-type grating, the high spectral resolution of 2.83-2.88 nm is reserved, the contradiction between the traditional fixed slit resolution and the signal-to-noise ratio is solved through slit self-adaptive adjustment, the gas concentration detection error is smaller than or equal to + / -3%, the characteristic absorption spectral lines of natural gas and coal gas key components are matched, the integrated design gives consideration to miniaturization and environmental adaptability, and the device is suitable for large-scale popularization and application. The field mobile detection requirement can be met, secondary spectrums and stray light are inhibited through the synergistic effect of the light filtering unit, the PGP coaxial structure and the light source light filtering design, the ambient light interference resistance is high, and the detection stability is high.

Description

Technical Field

[0001] This invention relates to the field of gas detection imaging spectrometer technology, specifically a gas detection imaging spectrometer based on DMD and a transmission grating. Background Technology

[0002] Natural gas (mainly composed of methane, ethane, and propane) and coal gas (mainly composed of carbon monoxide and hydrogen) are commonly used fuels, and leak detection is crucial for safe production and environmental protection. Among existing gas detection technologies, gas chromatography, while highly accurate, has a long analysis time (up to 45 minutes) and requires specialized operation, making it difficult to meet the needs of rapid on-site detection. Traditional infrared spectroscopy can only indicate the presence of gas and cannot achieve quantitative analysis of multiple components. Conventional imaging spectrometers use a fixed slit design, which presents a trade-off between resolution and signal-to-noise ratio, and lacks specificity in screening for characteristic gas spectral lines, is easily affected by ambient light, and has limited detection sensitivity.

[0003] Meanwhile, existing DMD-based spectral detection technologies are mostly applied to the ultraviolet or infrared bands, failing to combine with the high-resolution spectral advantages of transmission gratings, and lacking customized stable light source adaptation designs—large fluctuations in ambient light intensity and incomplete spectral coverage result in weak gas characteristic absorption signals, insufficient detection accuracy and stability, making it difficult to adapt to the on-site rapid detection needs of multi-component gases such as natural gas and coal gas. Therefore, an improved technology is urgently needed to solve this problem in the existing technology. Summary of the Invention

[0004] The purpose of this invention is to provide a gas detection imaging spectrometer that overcomes the shortcomings of existing gas detection technologies and is based on a DMD and a transmission grating. By integrating a halogen lamp light source component, it achieves stable beam output in the 400-1000nm band. Combined with the DMD virtual slit and high-resolution spectroscopic design, it enables rapid identification and quantitative detection of multi-component gases such as natural gas and coal gas. This gas detection imaging spectrometer balances detection accuracy and field adaptability, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a gas detection imaging spectrometer based on DMD and a transmission grating, comprising a gas detection imaging spectrometer body, a base, a corner mount, and a camera interface ring, wherein the gas detection imaging spectrometer body is provided with a base, a corner mount, and a camera interface ring;

[0006] The base has a lens tube A inside, and inside the lens tube A, from left to right, there are filter A, lens A, lens B, lens C, cemented lens A, and lens D.

[0007] The interior of the corner bracket is provided with lens a, lens b, lens c, cemented lens a, and lens d in sequence from right to left;

[0008] The gas detection imaging spectrometer body (38) has a lens mounting plate at one end, which is installed in conjunction with the left end of the base. A cover plate is provided on one side of the outer wall of the base. The gas detection imaging spectrometer body has a camera interface ring at the other end, which is installed in conjunction with one end of the corner bracket.

[0009] The left end of the gas detection imaging spectrometer is equipped with a digital micromirror device (DMD) and an incident optics module, and a halogen lamp light source assembly is located directly below the incident optics module.

[0010] Preferably, a lens barrel retaining ring is provided on one side of the filter A, a spacer A is provided between the filter A and the lens A, a spacer B is provided between the lens A and the lens B, a spacer C is provided between the lens B and the lens C, a Mylar plate A is provided between the lens C and the lens A, and a spacer D is provided on one side of the lens A.

[0011] Preferably, a spacer b is provided between the lens a and the lens b inside the corner mount, a spacer c is provided between the lens b and the lens c, a Mylar plate a is provided between the lens c and the cemented lens a, and a spacer d is provided between the cemented lens a and the lens d.

[0012] Preferably, the left end of the corner bracket is provided with a slotted plate mounting ring and a slotted plate, and the right end of the corner bracket is provided with a grating mounting ring, a grating pressure ring, a grating, a prism mounting ring, and a prism.

[0013] Preferably, the incident optical module includes a converging lens and a dustproof window, and the object-side NA of the converging lens is 0.205.

[0014] Preferably, the internal signal processing module of the digital micromirror device (DMD) incorporates a spectral correction algorithm to compensate for spectral shifts caused by temperature changes (5~40℃), resulting in a concentration detection accuracy error of ≤±3%.

[0015] Preferably, the halogen lamp light source assembly includes a halogen lamp, a quartz collimating lens, an ultraviolet cutoff filter, an aperture, and a high-precision DC regulated power supply. The halogen lamp light source has a power of 5-20W, emitting a broad-spectrum beam of 300-2500nm, with the core covering the target wavelength band of 400-1000nm. The quartz collimating lens has a focal length of 10-20mm, the ultraviolet cutoff filter has a cutoff wavelength of 400nm to eliminate ultraviolet stray light, and the aperture of the aperture is 2-5mm.

[0016] The halogen lamp light source assembly is connected to the incident optical module via a three-dimensional adjustment frame. The distance between the lamp body and the converging lens is 5~10cm. The assembly is equipped with a heat dissipation structure to control the surface temperature of the lamp body to ≤80℃ and the beam coupling efficiency to ≥85%.

[0017] Preferably, the assembly and debugging process of a gas detection imaging spectrometer based on DMD and transmission grating includes the following steps:

[0018] Install the halogen lamp, quartz collimating lens, ultraviolet cut-off filter, and aperture in sequence, ensuring that the coaxiality error of each component is ≤0.02mm; connect the regulated power supply and cooling fan, test the stability of the light source output, and ensure that the light intensity fluctuation is ≤±2% / h; connect the light source component to the incident optical module through the three-dimensional adjustment frame, and adjust the position to align the beam center with the axis of the converging lens, with a coupling efficiency ≥85%;

[0019] Assemble the components in the following order: incident optical module → DMD → transmission grating spectral module → detector module. Ensure that the coaxiality error of each component is ≤0.01mm. Adjust the PGP coaxial structure so that the grating lines are perpendicular to the tilt direction of the prism. After fixing, maintain a gap of 2mm.

[0020] The micromirror array is driven by a controller, and three virtual slit widths of 20μm, 50μm and 100μm are set respectively. The light transmission consistency of the slit is calibrated using a halogen lamp light source, and the error is controlled within ±5%.

[0021] Using standard gas samples (5% methane, 1% carbon monoxide, 2% ethane, and 1% propane), characteristic absorption spectra were collected under standard conditions (25℃, 1 atm) by excitation with a halogen lamp. A standard spectral library was established and stored in the signal processing module. The spectral line matching accuracy was ≥98% through algorithm optimization.

[0022] Fix each module to the aluminum alloy shell, install dustproof and waterproof windows, control the shell size to 60×60×200mm, and weigh ≤1.2kg. Connect the power module (supports DC 12V power supply) and the alarm module to complete the system integration.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) The gas detection imaging spectrometer body 38 provides a continuous and stable light beam of 400-1000nm, with light intensity fluctuation ≤±2% / h and coupling efficiency ≥85%, solving the detection error problem caused by unstable ambient light and providing a reliable basis for the extraction of gas characteristic absorption signals;

[0025] (2) The combination of DMD virtual slit and transmission grating not only retains the high spectral resolution of 2.83nm-2.88nm, but also solves the contradiction between the resolution and signal-to-noise ratio of traditional fixed slits through adaptive slit adjustment, with a gas concentration detection error ≤±3%;

[0026] (3) The optical path and light source in the 400-1000nm band were specifically optimized to match the characteristic absorption spectra of key components of natural gas and coal gas. The response time for simultaneous detection of multiple components is ≤3s, which is far superior to the efficiency of gas chromatography.

[0027] (4) The integrated design takes into account both miniaturization and environmental adaptability. The working temperature range is 5-40℃ and the IP54 protection rating can meet the needs of mobile on-site testing. Through the synergistic effect of the filter unit, PGP coaxial structure and light source filter design, secondary spectrum and stray light are suppressed, the ability to resist ambient light interference is strong and the detection stability is high;

[0028] (5) This invention overcomes the defects of existing gas detection technology and provides a gas detection imaging spectrometer based on DMD and transmission grating. By integrating halogen lamp light source components, it achieves stable beam output in the 400-1000nm band. Combined with DMD virtual slit and high-resolution spectral design, it can quickly identify and quantitatively detect multi-component gases such as natural gas and coal gas, taking into account both detection accuracy and on-site adaptability. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the gas detection imaging spectrometer of the present invention;

[0030] Figure 2 This is a schematic diagram of the internal component structure of the gas detection imaging spectrometer of the present invention;

[0031] Figure 3 This is a block diagram of the optical path system of the present invention;

[0032] Figure 4 This is a graph showing the spectral shift of the present invention;

[0033] Figure 5 This is a schematic diagram of the spectral distortion curve of the present invention.

[0034] In the diagram: 1. Lens mounting plate; 2. Base; 3. Corner mount; 4. Camera interface ring; 5. Slit plate mounting ring; 6. Slit plate; 7. Lens barrel A; 8. Lens barrel retaining ring; 9. Filter A; 10. Spacer A; 11. Lens A; 12. Spacer B; 13. Lens B; 14. Spacer C; 15. Lens C; 16. Mylar plate A; 17. Cemented lens A; 18. Spacer D; 19. Lens D; 20. Grating mounting ring; 21. Grating retaining ring; 22. Grating; 2 3. Prism mounting ring; 24. Prism; 25. Lens tube B; 26. Filter mounting ring; 27. Filter B; 28. Cover plate; 29. ​​Lens a; 30. Spacer b; 31. Lens b; 32. Spacer c; 33. Lens c; 34. Mylar plate a; 35. Cemented lens a; 36. Spacer d; 37. Lens d; 38. Gas detection imaging spectrometer body; 39. Digital micromirror device (DMD); 40. Halogen lamp light source assembly; 41. Incident optics module. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Please see Figures 1-5 The present invention provides a technical solution: a gas detection imaging spectrometer based on DMD and transmission grating, comprising a gas detection imaging spectrometer body 38, a base 2, a corner mount 3, and a camera interface ring 4, characterized in that: the gas detection imaging spectrometer body 29 is provided with a base 2, a corner mount 3, and a camera interface ring 4.

[0037] The base 2 has a lens barrel A7 inside, and from left to right inside the lens barrel A7 are a filter A9, a lens A11, a lens B13, a lens C15, a cemented lens A17, and a lens D19.

[0038] A lens barrel retaining ring 8 is provided on one side of the filter A9. A spacer ring A10 is provided between the filter A9 and the lens A11. A spacer ring B12 is provided between the lens A11 and the lens B13. A spacer ring C14 is provided between the lens B13 and the lens C15. A Mylar plate A16 is provided between the lens C15 and the lens A17. A spacer ring D18 is provided on one side of the lens A17.

[0039] The interior of the corner mount 3, from right to left, is equipped with lens a29, lens b31, lens c33, cemented lens a35, and lens d37.

[0040] An internal spacer b30 is provided between lens a29 and lens b31 inside the corner mount 3. An internal spacer c32 is provided between lens b31 and lens c33. A Mylar sheet a34 is provided between lens c33 and cemented lens a35. An internal spacer d36 is provided between cemented lens a35 and lens d37.

[0041] A lens mounting plate 1 is provided at one end of the gas detection imaging spectrometer body 38. The lens mounting plate 1 is installed in conjunction with the left end of the base 2. A cover plate 28 is provided on one side of the outer wall of the base 2. A camera interface ring 4 is provided at the other end of the gas detection imaging spectrometer body 38. The camera interface ring 4 is installed in conjunction with one end of the corner bracket 3.

[0042] The left end of the gas detection imaging spectrometer body 38 is equipped with a digital micromirror device (DMD) 39 and an incident optics module 41. A halogen lamp light source assembly 40 is located directly below the incident optics module 41. The incident optics module 41 includes a converging lens and a dustproof window. The object-side NA of the converging lens is 0.205. The halogen lamp light source assembly 40 provides a continuous and stable light beam of 400-1000nm with light intensity fluctuation ≤±2% / h and coupling efficiency ≥85%, solving the detection error problem caused by unstable ambient light and providing a reliable basis for the extraction of gas characteristic absorption signals.

[0043] The left end of the corner bracket 3 is provided with a slit plate mounting ring 5 and a slit plate 6, and the right end of the corner bracket 3 is provided with a grating mounting ring 20, a grating pressure ring 21, a grating 22, a prism mounting ring 23, and a prism 24.

[0044] The Digital Micromirror Device (DMD) 39's internal signal processing module incorporates a spectral correction algorithm to compensate for spectral shifts caused by temperature variations (5-40℃), achieving a concentration detection accuracy error of ≤±3%. The DMD's virtual slit, combined with a transmission grating, retains the high spectral resolution of 2.83nm-2.88nm while resolving the conflict between resolution and signal-to-noise ratio in traditional fixed slits through adaptive slit adjustment, resulting in a gas concentration detection error of ≤±3%.

[0045] The halogen lamp light source assembly 40 includes a halogen lamp, a quartz collimating lens, an ultraviolet cut-off filter, an aperture, and a high-precision DC regulated power supply. The halogen lamp light source has a power of 5-20W and emits a broad-spectrum beam of 300-2500nm, with the core covering the target wavelength band of 400-1000nm. The quartz collimating lens has a focal length of 10-20mm, the ultraviolet cut-off filter has a cut-off wavelength of 400nm to eliminate ultraviolet stray light, and the aperture of the aperture is 2-5mm.

[0046] The halogen lamp light source assembly 40 is connected to the incident optical module via a three-dimensional adjustment frame. The distance between the lamp body and the converging lens is 5~10cm. The assembly is equipped with a heat dissipation structure to control the surface temperature of the lamp body to ≤80℃ and the beam coupling efficiency to ≥85%.

[0047] The assembly and debugging process of a gas detection imaging spectrometer based on DMD and transmission grating includes the following steps:

[0048] Install the halogen lamp, quartz collimating lens, ultraviolet cut-off filter and aperture in sequence, ensuring that the coaxiality error of each component is ≤0.02mm; connect the regulated power supply and cooling fan, test the stability of the light source output, and ensure that the light intensity fluctuation is ≤±2% / h; connect the light source component and the incident optical module through the three-dimensional adjustment frame, adjust the position so that the beam center is aligned with the axis of the converging lens, and the coupling efficiency is ≥85%.

[0049] Assemble the components in the following order: incident optics module → DMD → transmission grating spectral module → detector module. Ensure that the coaxiality error of each component is ≤0.01mm. Adjust the PGP coaxial structure so that the grating lines are perpendicular to the tilt direction of the prism. After fixing, maintain a gap of 2mm.

[0050] The micromirror array is driven by a controller, and three virtual slit widths of 20μm, 50μm, and 100μm are set respectively. The light transmission consistency of the slits is calibrated using a halogen lamp light source, and the error is controlled within ±5%.

[0051] Using standard gas samples (5% methane, 1% carbon monoxide, 2% ethane, and 1% propane), characteristic absorption spectra were collected under standard conditions (25℃, 1 atm) by excitation with a halogen lamp. A standard spectral library was established and stored in the signal processing module. Through algorithm optimization, the spectral matching accuracy was achieved to ≥98%. The signal processing module uses an ARM Cortex-M4 processor and has built-in characteristic absorption spectral libraries for natural gas (methane, ethane, propane) and coal gas (carbon monoxide, hydrogen). It integrates temperature compensation algorithms and spectral comparison algorithms, and the data processing speed is ≥1000 frames / second.

[0052] Fix each module to the aluminum alloy shell, install dustproof and waterproof windows, control the shell size to 60×60×200mm, and weigh ≤1.2kg. Connect the power module (supports DC 12V power supply) and the alarm module to complete the system integration.

[0053] The gas detection imaging spectrometer 38 provides a continuous and stable beam of 400-1000nm, with light intensity fluctuation ≤±2% / h and coupling efficiency ≥85%, solving the detection error problem caused by unstable ambient light and providing a reliable foundation for the extraction of gas characteristic absorption signals. The combination of DMD virtual slit and transmission grating retains the high spectral resolution of 2.83nm-2.88nm, while resolving the contradiction between resolution and signal-to-noise ratio in traditional fixed slits through adaptive slit adjustment. The gas concentration detection error is ≤±3%. The optical path and light source are specifically optimized for the 400-1000nm band to match the characteristic absorption spectra of key components of natural gas and coal gas. The response time for simultaneous detection of multiple components is ≤3s, far exceeding the efficiency of gas chromatography. The integrated design takes into account both miniaturization and environmental adaptability. The operating temperature range is 5-40℃, and the IP54 protection rating can meet the needs of mobile on-site detection. Through the synergistic effect of the filter unit, PGP coaxial structure and light source filter design, secondary spectrum and stray light are suppressed, resulting in strong resistance to ambient light interference and high detection stability.

[0054] This invention overcomes the shortcomings of existing gas detection technologies and provides a gas detection imaging spectrometer based on DMD and a transmission grating. By integrating a halogen lamp light source component, it achieves stable beam output in the 400-1000nm band. Combined with the DMD virtual slit and high-resolution spectroscopic design, it can quickly identify and quantitatively detect multi-component gases such as natural gas and coal gas, while taking into account both detection accuracy and field adaptability.

[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A gas detection imaging spectrometer based on DMD and a transmission grating, comprising a gas detection imaging spectrometer body (38), a base (2), a corner mount (3), and a camera interface ring (4), characterized in that: The gas detection imaging spectrometer body (29) is provided with a base (2), a corner mount (3), and a camera interface ring (4); The base (2) is provided with a lens tube A (7) inside, and from left to right inside the lens tube A (7) are a filter A (9), a lens A (11), a lens B (13), a lens C (15), a cemented lens A (17), and a lens D (19). The corner bracket (3) is provided with lens a (29), lens b (31), lens c (33), cemented lens a (35), and lens d (37) from right to left inside. The gas detection imaging spectrometer body (38) has a lens mounting plate (1) at one end, which is installed in conjunction with the left end of the base (2). A cover plate (28) is provided on one side of the outer wall of the base (2). The gas detection imaging spectrometer body (38) has a camera interface ring (4) at the other end, which is installed in conjunction with one end of the corner bracket (3). The left end of the gas detection imaging spectrometer body (38) is equipped with a digital micromirror device (DMD) (39) and an incident optical module (41), and a halogen lamp light source assembly (40) is provided directly below the incident optical module (41).

2. The gas detection imaging spectrometer based on DMD and transmission grating according to claim 1, characterized in that: The filter A (9) is provided with a lens barrel pressure ring (8) on one side, a spacer A (10) is provided between the filter A (9) and the lens A (11), a spacer B (12) is provided between the lens A (11) and the lens B (13), a spacer C (14) is provided between the lens B (13) and the lens C (15), a Mylar plate A (16) is provided between the lens C (15) and the lens A (17), and a spacer D (18) is provided on one side of the lens A (17).

3. A gas detection imaging spectrometer based on DMD and a transmission grating according to claim 1, characterized in that: The corner mount (3) has a spacer b (30) between the lens a (29) and the lens b (31), a spacer c (32) between the lens b (31) and the lens c (33), a Mylar plate a (34) between the lens c (33) and the cemented lens a (35), and a spacer d (36) between the cemented lens a (35) and the lens d (37).

4. A gas detection imaging spectrometer based on DMD and transmission grating according to claim 1, characterized in that: The left end of the corner bracket (3) is provided with a slit plate mounting ring (5) and a slit plate (6), and the right end of the corner bracket (3) is provided with a grating mounting ring (20), a grating pressure ring (21), a grating (22), a prism mounting ring (23), and a prism (24).

5. A gas detection imaging spectrometer based on DMD and transmission grating according to claim 1, characterized in that: The incident optical module (41) includes a converging lens and a dustproof window, and the object-side NA of the converging lens is 0.

205.

6. A gas detection imaging spectrometer based on DMD and transmission grating according to claim 1, characterized in that: The digital micromirror device (DMD) (39) has a built-in spectral correction algorithm in its internal signal processing module to compensate for spectral shifts caused by temperature changes (5~40℃), and the concentration detection accuracy error is ≤±3%.

7. A gas detection imaging spectrometer based on DMD and transmission grating according to claim 1, characterized in that: The halogen lamp light source assembly (40) includes a halogen lamp, a quartz collimating lens, an ultraviolet cut-off filter, an aperture, and a high-precision DC regulated power supply. The halogen lamp light source power is 5-20W, emitting a 300-2500nm broad-spectrum beam, with the core covering the 400-1000nm target wavelength band. The focal length of the quartz collimating lens is 10-20mm, the ultraviolet cut-off filter has a cut-off wavelength of 400nm to eliminate ultraviolet stray light, and the aperture of the aperture is 2-5mm. The halogen lamp light source assembly (40) is connected to the incident optical module via a three-dimensional adjustment frame. The distance between the lamp body and the converging lens is 5~10cm. The assembly is equipped with a heat dissipation structure to control the surface temperature of the lamp body to ≤80℃ and the beam coupling efficiency to ≥85%. The assembly and debugging process of the gas detection imaging spectrometer based on DMD and transmission grating as described in claim 1 includes the following steps: Install the halogen lamp, quartz collimating lens, ultraviolet cut-off filter, and aperture in sequence, ensuring that the coaxiality error of each component is ≤0.02mm; connect the regulated power supply and cooling fan, test the stability of the light source output, and ensure that the light intensity fluctuation is ≤±2% / h; connect the light source component to the incident optical module through the three-dimensional adjustment frame, and adjust the position to align the beam center with the axis of the converging lens, with a coupling efficiency ≥85%; Assemble the components in the following order: incident optical module → DMD → transmission grating spectral module → detector module. Ensure that the coaxiality error of each component is ≤0.01mm. Adjust the PGP coaxial structure so that the grating lines are perpendicular to the tilt direction of the prism. After fixing, maintain a gap of 2mm. The micromirror array is driven by a controller, and three virtual slit widths of 20μm, 50μm and 100μm are set respectively. The light transmission consistency of the slit is calibrated using a halogen lamp light source, and the error is controlled within ±5%. Using standard gas samples (5% methane, 1% carbon monoxide, 2% ethane, and 1% propane), characteristic absorption spectra were collected under standard conditions (25℃, 1 atm) by excitation with a halogen lamp. A standard spectral library was established and stored in the signal processing module. The spectral line matching accuracy was ≥98% through algorithm optimization. Fix each module to the aluminum alloy shell, install dustproof and waterproof windows, control the shell size to 60×60×200mm, and weigh ≤1.2kg. Connect the power module (supports DC 12V power supply) and the alarm module to complete the system integration.

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