An infrared digital holography-based atmospheric humidity change detection device and method

Abstract

The application discloses an atmospheric humidity change detection device and method based on infrared digital holography, and belongs to the field of infrared holography technology. The atmospheric humidity measurement device comprises an infrared laser, a beam splitter I, a beam splitter II, a beam expander I, a beam expander II, a pinhole filter I, a pinhole filter II, a lens I, a lens II, an infrared lens I, an infrared lens II and a mirror I. The application applies fiber infrared holography technology to the measurement of atmospheric humidity. MATLAB programming is used to process the photographed infrared holographic interference pattern, so that the interference pattern contrast under the current atmospheric humidity is obtained. When the atmospheric humidity changes slightly, the corresponding interference holographic fringe pattern contrast will change obviously. The application of infrared digital holography to the detection of atmospheric humidity change can detect the slight change of atmospheric humidity, and real-time high-precision results are obtained, and the anti-interference capability is improved.

Description

Technical Field

[0001] This invention discloses an atmospheric humidity change detection device and method based on infrared digital holography, belonging to the application field of infrared digital holography. Background Technology

[0002] The recording process of digital holography is no different from that of traditional holography. Because the recorded information is digitized, it can be reproduced and processed by a computer without the need for a reference beam, allowing the computer to recreate the original image. After years of research, digital holography has been widely used in 3D information measurement and recording, encryption, and image recognition, requiring rapid information processing. Currently, holographic detection primarily uses visible light lasers as the light source. With the research into infrared characteristics and the development of infrared lasers and infrared CCDs, infrared holographic detection technology has gradually developed. Replacing the light source in holographic detection technology with an infrared laser leads to the concept of infrared holography. Infrared digital holography is an interdisciplinary study of infrared and digital holography, combining the technical characteristics of visible light digital holography and infrared light.

[0003] Semiconductor manufacturing plants require stable environments throughout the year, with stringent requirements for various air conditioning parameters such as temperature, humidity, and air cleanliness. Unlike other constant temperature and humidity systems, electronic products are highly sensitive to static electricity, and high humidity significantly impacts their quality. Therefore, precise humidity control is crucial to prevent damage from static electricity caused by low humidity and corrosion from condensation caused by excessive humidity. Furthermore, humidity sensing is essential not only in semiconductor manufacturing but also for ensuring proper conditions for valuable assets. For example, galleries, museums, and art collectors maintain stable environmental conditions for their collections, as moisture can be disastrous for paintings, drawings, prints, mosaics, and sculptures. In agriculture, water is paramount for healthy plants, making relative humidity critical. Therefore, precise control of temperature and humidity can significantly improve the performance of modern agriculture.

[0004] Currently, electronic humidity measurement methods have several theoretical and practical limitations. Electronic humidity sensors, due to the effects of dust, oil, and harmful gases, age and lose accuracy over time. Humidity sensors utilize semiconductor technology, thus requiring specific ambient temperatures; exceeding these temperatures will damage the sensor, making them more suitable for clean, room-temperature environments. Other types include cold mirror, fully absorption electrolytic, and thin-film capacitive sensors. However, these devices have limited measurement accuracy and require a certain response time, failing to meet the demands for high precision and timeliness.

[0005] Water vapor can absorb some long-wave infrared light; these wavelengths are called the characteristic absorption wavelength range. When infrared light within this range shines through the atmosphere, the transmitted infrared energy is weakened if moisture is present. Different wavelengths of infrared light have different absorption coefficients in the atmosphere. Within certain wavelength ranges, infrared light transmittance is highly sensitive to changes in atmospheric water vapor content; even small changes in water vapor content can significantly affect the intensity of transmitted infrared light. The visibility of infrared holographic interference fringes depends on the intensity ratio. The two beams are the object beam and the reference beam, respectively. The reference beam remains constant, while the object beam changes due to variations in atmospheric water vapor content, leading to a change in the intensity ratio of the object and reference beams. This, in turn, alters the visibility of the interference fringes produced by the object-reference beam interference. By analyzing the magnitude of this change in fringe visibility, information about atmospheric water vapor variations can be obtained. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, this invention provides an atmospheric humidity change detection device and method based on infrared digital holography. Utilizing the characteristic that certain bands of infrared light are easily absorbed by water vapor, this atmospheric humidity change detection device and method based on infrared digital holography combines the characteristics of infrared light with the advantages of holographic technology. This ensures accuracy, and significantly improves recognition efficiency, convenience, and visualization, effectively overcoming the shortcomings of traditional equipment.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An atmospheric humidity change detection device based on infrared digital holography includes: an infrared laser, beam splitter I, beam splitter II, beam expander I, beam expander II, pinhole filter I, pinhole filter II, lens I, lens II, infrared lens I, infrared lens II, reflector I, reflector II, infrared CCD, computer, and an outer protective device. The infrared laser, beam splitter I, beam splitter II, beam expander I, beam expander II, pinhole filter I, pinhole filter II, lens I, lens II, reflector I, reflector II, and infrared CCD are fixed inside the opaque outer protective device. Infrared lenses I and II are disposed on the outer wall of the perforated portion of the outer protective device. The computer is externally connected to the outer CCD.

[0009] An infrared laser emits a laser beam, which is split into two beams by beam splitter I: a reference beam and an object beam. The reference beam is reflected by a mirror and then passes through beam expander II, pinhole filter II, and lens II in sequence to become a parallel beam. This parallel beam then reaches beam splitter II.

[0010] The object beam passes sequentially through beam expander I, pinhole filter I, and lens I to become a parallel beam. This parallel beam enters the air through infrared lens I, where the infrared light is partially absorbed. After passing through infrared lens II, it is reflected by mirror II and reaches beam splitter II. The reference beam and the object beam interfere on beam splitter II to form an interference hologram. The interference hologram is then transmitted to an infrared CCD and then to a computer, where the computer performs contrast calculations and comparisons of the hologram.

[0011] As a preferred embodiment of the present invention, taking advantage of the characteristic that infrared light can be absorbed by moisture in the atmosphere, an infrared laser with a wavelength of not less than 760nm is selected as the laser.

[0012] The infrared laser is model iFLEX-Agile. The iFLEX-Agile high-power continuous-wave optical parametric oscillator (OPO) can achieve any desired wavelength setting from 1.47μm to 2μm and 2.3μm to 3.8μm. The emission linewidth ranges from 500GHz to below 1MHz, depending on the configuration and specific application. Extended wavelength ranges can also be customized upon request, with narrow linewidths of less than 1MHz from 2300nm to 3800nm ​​and output power exceeding 1W.

[0013] Preferably, the infrared laser uses infrared light with a wavelength of 3.0–3.5 μm. Different wavelengths of infrared light have different transmittance in the atmosphere. The wavelength range of 3.0–3.5 μm selected in this invention is easily absorbed by moisture, and this characteristic can be used to accurately reflect changes in the moisture content of the air.

[0014] More preferably, the infrared laser selects infrared light with a wavelength of 3200nm. Infrared light of this wavelength is easily absorbed by water vapor, and the absorption rate varies significantly with different water vapor contents. This characteristic can be used to accurately reflect even the smallest changes in the moisture content of the air.

[0015] Lasers also have high coherence. Dust in the air, optical components, or the laser itself often cause some scattered light to interfere with the process. Pinhole filters can filter out stray light, making the quality of holographic imaging better.

[0016] In a preferred embodiment of the present invention, lens I and lens II are germanium lenses, silicon lenses or glass lenses.

[0017] In a preferred embodiment of the present invention, the beam splitter I and beam splitter II are germanium beam splitters, silicon beam splitters or glass beam splitters.

[0018] In a preferred embodiment of the present invention, the beam expander I and beam expander II are germanium beam expanders, silicon beam expanders or glass beam expanders.

[0019] In a preferred embodiment of the present invention, the sensing band of the infrared CCD includes the infrared laser band, and it has a high-sensitivity CCD image sensor, model TCH-1.4ICE, which receives images synchronously with the infrared laser.

[0020] In a preferred embodiment of the present invention, the infrared lens I and the infrared lens II can filter out stray light by using infrared light with an infrared band including the center band length of an infrared laser.

[0021] In a preferred embodiment of the present invention, the outer protective device is an opaque shell, and the inner wall is covered with a pure black material to absorb other infrared light entering the interior, so as to prevent interference with the infrared CCD and cause noise in the infrared hologram.

[0022] The atmospheric humidity change detection device based on infrared digital holography described in this invention can be used in different scenarios. Depending on the application scenario, the sensitivity requirements for atmospheric humidity changes are different, and the infrared laser can be adjusted to a suitable wavelength according to the requirements.

[0023] This invention claims protection for a method of using the infrared digital holographic atmospheric humidity change detection device, comprising the following steps:

[0024] S1: Turn on the infrared laser. The object beam passes through the atmosphere to be measured. After the infrared light is partially absorbed, it returns to the atmospheric humidity change detection device based on infrared digital holography. The object beam and the reference light wave superimpose to produce an interference hologram. The intensity information of the object beam is collected by using infrared light holography.

[0025] S2: Record the contrast of the interference hologram under normal conditions and the interference hologram after slight changes in atmospheric humidity. The records are made by an infrared CCD and transmitted to a computer for storage.

[0026] S3: By calculating the contrast of holograms, computers can identify minute changes in atmospheric moisture and assess the accuracy requirements for humidity changes in different scenarios.

[0027] In a preferred embodiment of the present invention, S1 specifically includes:

[0028] When the infrared laser is turned on, the emitted infrared laser light is split into two beams by beam splitter I: an object beam and a reference beam. In the reference beam's path, the infrared light is reflected by a mirror and then transmitted to beam expander II for beam amplification. It is then filtered by pinhole filter II, and after filtering, the laser light passes through lens II to become parallel light. In the object beam's path, the infrared laser light is transmitted to beam expander I for beam amplification, and then filtered by pinhole filter I. After filtering, the laser light passes through lens I to become parallel light. The parallel light passes through infrared lens I and then through the air to be measured. The infrared light is partially absorbed by the moisture in the air. After the transmitted beam is filtered by infrared lens II to remove stray light, the intensity information of the object beam changes. The reference beam and object beam interfere with each other on beam splitter II to obtain an interference hologram.

[0029] In a preferred embodiment of the present invention, S3 specifically includes:

[0030] Interference patterns of the hologram were acquired using a CCD when the atmospheric humidity remained constant. The fringe contrast of the hologram was calculated using Matlab. When the atmospheric humidity changed slightly, the atmosphere absorbed different proportions of infrared light in the object beam path, causing a change in the intensity ratio of the object beam to the reference beam. Interference occurred between the object and reference beams with different intensity ratios. The reference beam path was sealed and set to a constant value. The fringe contrast changed, and the changed fringe contrast was calculated. The changed image contrast was subtracted from the unchanged image contrast. If the difference was less than the reasonable range of image contrast variation corresponding to the allowable range of atmospheric humidity change, there was no effect. If the difference was greater than the reasonable range of image contrast variation, there was an effect.

[0031] Compared with existing traditional technologies, the beneficial effects of the present invention are as follows:

[0032] (1) Real-time monitoring and calculation by computer provides a faster response speed than traditional methods and instruments, meeting the needs of information technology.

[0033] (2) The measurement accuracy is high, which can meet the humidity change monitoring requirements of high-precision semiconductor manufacturing environment, and the system is relatively stable and will not cause time drift or other effects.

[0034] (3) The selected laser can be modulated with different wavelengths. The absorption intensity of infrared light of different wavelengths by the atmosphere is different. With this characteristic, it can be applied to the accuracy requirements of humidity changes in different environments. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the atmospheric humidity change detection device based on infrared digital holography according to the present invention.

[0036] Figure 2This is an external schematic diagram of the atmospheric humidity change detection device based on infrared digital holography according to the present invention.

[0037] Figure 3 This is a flowchart illustrating the method of using the atmospheric humidity change detection device described in this invention.

[0038] In the diagram: 1-Infrared laser, 2-Beam splitter I, 3-Reflector I, 4-Beam expander I, 5-Beam expander II, 6-Pinhole filter I, 7-Pinhole filter II, 8-Lens I, 9-Lens II, 10-Infrared lens I, 11-Infrared lens II, 12-Reflector II, 13-Beam splitter II, 14-Infrared CCD, 15-Computer, 16-Outer protective device. Detailed Implementation

[0039] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0040] Example 1

[0041] like Figure 1 As shown, the atmospheric humidity change detection device based on infrared digital holography includes: an infrared laser 1, a beam splitter I 2, a reflector I 3, a beam expander I 4, a beam expander II 5, a pinhole filter I 6, a pinhole filter II 7, a lens I 8, a lens II 9, an infrared lens I 10, an infrared lens II 11, a reflector II 12, a beam splitter II 13, an infrared CCD 14, a computer 15, and an outer protective device 16. The infrared laser 1, beam splitter I 2, reflector I 3, beam expander I 4, beam expander II 5, pinhole filter I 6, pinhole filter II 7, lens I 8, lens II 9, reflector II 12, beam splitter II 13, and infrared CCD 14 are disposed inside the outer protective device 16; infrared lens I 10 and infrared lens II 11 are disposed on the sidewall of the outer protective device 16; the computer 15 is outside the outer protective device 16 and is connected to the infrared CCD 14 via a cable.

[0042] Inside the outer protective device 16, the infrared laser 1 emits a laser beam, which is split into two laser beams by the beam splitter I 2, namely a reference beam and an object beam. After being reflected by the reflector I 3, the reference beam passes through the beam expander II 5, the pinhole filter II 7 and the lens II 9 in sequence to become a parallel beam. The parallel beam reaches the beam splitter II 13.

[0043] The object beam passes sequentially through beam expander I 4, pinhole filter I 6, and lens I 8 to become a parallel beam. This parallel beam passes through infrared lens I 10 and enters the air where the infrared light is partially absorbed. After passing through infrared lens II 11, it is reflected by mirror II 12 and reaches beam splitter II 13. The reference beam and the object beam interfere on beam splitter II 13 to form an interference hologram. The interference hologram is then transmitted to infrared CCD 14 and then to computer 15, where the computer performs contrast calculation and comparison of the hologram.

[0044] Preferably, the infrared laser 1 described in this embodiment is an iFLEX-Agile model. The iFLEX-Agile high-power continuous-wave optical parametric oscillator (OPO) employs optimized optics to fine-tune specific wavelengths from NIR to MIR. Controlled via USB, this component enables rapid and reproducible setting of any desired wavelength from 1.47μm to 2μm and 2.3μm to 3.8μm without the need to replace optics or modules.

[0045] Preferably, iFLEX-Agile lasers feature narrow linewidth and high power; emission linewidths range from 500 GHz to below 1 MHz, depending on the configuration and specific application; iFLEX-Agile can also be customized to extend the wavelength range to 2,300 nm to 3,800 nm with narrow linewidths less than 1 MHz and output power greater than 1 W (depending on wavelength, excluding approximately 2.8 μm of OH absorption).

[0046] Preferably, lens I 8 and lens II 8 are germanium lenses; beam splitter I 2 and beam splitter II 13 are germanium beam splitters; and beam expander I 4 and beam expander II 5 are germanium beam expanders.

[0047] Preferably, the infrared CCD15 has an infrared laser band in its sensing band and a high-sensitivity CCD image sensor, model TCH-1.4ICE, which receives images synchronously with the infrared laser.

[0048] Preferably, the infrared lens I10 and infrared lens II11 can filter out stray light by using infrared light in the infrared band, including the center band length of the infrared laser 1.

[0049] Preferably, the outer protective device 16 is an opaque shell, and the inner wall is covered with a pure black material to absorb other infrared light entering the interior, so as to prevent interference with the infrared CCD 15 and the generation of noise in the infrared hologram.

[0050] This embodiment uses the infrared digital holographic atmospheric humidity change detection device to monitor minute changes in air humidity in a semiconductor manufacturing environment. The method includes the following steps:

[0051] S1: Turn on infrared laser 1. The object beam passes through the atmosphere to be measured. After the infrared light is partially absorbed, it returns to the atmospheric humidity change detection device based on infrared digital holography. The object beam and the reference light wave are superimposed to produce an interference hologram. The intensity information of the object beam is collected by using infrared light holography.

[0052] S2: Record the contrast of the interference hologram under normal conditions and the interference hologram after slight changes in atmospheric humidity. The records are made by infrared CCD 15 and transmitted to the computer for storage.

[0053] S3: Computer 16 calculates the contrast of the hologram. Changes in the hologram's contrast can reflect minute changes in atmospheric moisture. It evaluates the accuracy requirements for humidity changes in different semiconductor manufacturing scenarios, specifically:

[0054] Interference patterns of the hologram were acquired using a CCD when the atmospheric humidity remained unchanged. The fringe contrast of the hologram was calculated using Matlab. When the atmospheric humidity changed slightly, the atmosphere in the object-optical path absorbed different proportions of infrared light, causing a change in the intensity ratio between the object beam and the reference beam. Interference occurred between the object and reference beams with different intensity ratios. The reference beam path was sealed and set to a constant value. The fringe contrast changed at this time, and the changed fringe contrast was calculated. The changed image contrast was subtracted from the unchanged image contrast. If the difference was less than the reasonable range of image contrast corresponding to the allowable range of atmospheric humidity changes, there was no effect. If the difference was greater than the reasonable range of image contrast, it was considered to have an effect.

[0055] Example 2

[0056] The infrared digital holographic-based atmospheric humidity change detection device is used to monitor the appropriate conditions for valuable assets, such as galleries, museums, and unearthed artifacts, where humidity conditions are relatively harsh. The method for detecting atmospheric humidity changes using the infrared digital holographic-based atmospheric humidity change detection device includes the following steps:

[0057] S1: Turn on infrared laser 1. The object beam passes through the atmosphere to be measured. After the infrared light is partially absorbed, it returns to the atmospheric humidity change detection device based on infrared digital holography. The object beam and the reference light wave are superimposed to produce an interference hologram. The intensity information of the object beam is collected by using infrared light holography.

[0058] S2: Record the contrast of the interference hologram under normal conditions and the interference hologram after slight changes in atmospheric humidity. The records are made by infrared CCD 15 and transmitted to the computer for storage.

[0059] S3: Computer 16 calculates the contrast of the hologram. Changes in the contrast of the hologram can reflect minute changes in atmospheric moisture, and assesses the accuracy requirements for humidity changes in scenarios such as cultural relic protection.

[0060] Example 3

[0061] The infrared digital holographic atmospheric humidity change detection device described in this embodiment is used in agricultural production, where some plants are highly sensitive to changes in air moisture. The method for detecting changes in atmospheric humidity using the infrared digital holographic atmospheric humidity change detection device includes the following steps:

[0062] S1: Turn on infrared laser 1. The object beam passes through the atmosphere to be measured. After the infrared light is partially absorbed, it returns to the atmospheric humidity change detection device based on infrared digital holography. The object beam and the reference light wave are superimposed to produce an interference hologram. The intensity information of the object beam is collected by using infrared light holography.

[0063] S2: Record the contrast of the interference hologram under normal conditions and the interference hologram after slight changes in atmospheric humidity. The records are made by infrared CCD 15 and transmitted to the computer for storage.

[0064] S3: Computer 16 calculates the contrast of the hologram. Changes in the contrast of the hologram can reflect minute changes in atmospheric moisture. It evaluates the accuracy requirements for humidity change for different plants that are sensitive to humidity changes.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An atmospheric humidity change detection device based on infrared digital holography, characterized in that, include: Infrared laser (1), beam splitter I (2), reflector I (3), beam expander I (4), beam expander II (5), pinhole filter I (6), pinhole filter II (7), lens I (8), lens II (9), infrared lens I (10), infrared lens II (11), reflector II (12), beam splitter II (13), infrared CCD (14), computer (15), outer protective device (16); the infrared CCD (14) is set inside the outer protective device (16), and lens I (8) and lens II (9) are set on the outer wall of the hollow part of the outer protective device; the computer is connected to the outer CCD outside the device; The infrared laser emits a laser beam, which is split into two laser beams by beam splitter I (2), namely a reference beam and an object beam. The reference beam is reflected by mirror I (3) and then passes through beam expander II (5), pinhole filter II (7) and lens II (9) in sequence to become a parallel beam. The parallel beam reaches beam splitter II (13). The object beam passes through beam expander I (4), pinhole filter I (6), and lens I (8) in sequence to become a parallel beam. The parallel beam passes through infrared lens I (10) and passes through the atmosphere. After being filtered by infrared lens II (11), it is reflected by mirror II (12) and reaches beam splitter II (13). The reference beam and the object beam interfere on the beam splitter II (13) to form an interference holographic fringe pattern. The interference holographic fringe pattern is then transmitted to the infrared CCD (14) and then to the computer (15). The infrared holographic interferogram is processed by using MATLAB programming to obtain the contrast of the interferogram under the current atmospheric humidity. When the atmospheric humidity changes slightly, the contrast of the corresponding interference holographic fringe pattern will change more significantly.

2. The atmospheric humidity change detection device based on infrared digital holography as described in claim 1, characterized in that: The infrared laser (1) is model iFLEX-Agile. The infrared laser (1) is used as a detection light source. Its wavelength is not less than 1000nm and it is located in the wavelength region where the absorption rate of the infrared atmospheric window is relatively obvious.

3. The atmospheric humidity change detection device based on infrared digital holography as described in claim 1, characterized in that: The outer protective device (16) is sealed and opaque, and the components inside the device are fixed inside the outer protective device.

4. The atmospheric humidity change detection device based on infrared digital holography as described in claim 1, characterized in that: The infrared lens I (10) and infrared lens II (11) are germanium lenses, silicon lenses or glass lenses, and the permissible band of the infrared lens is matched with the center band of the infrared laser; the lens I (8) and lens II (9) are germanium lenses, silicon lenses or glass lenses.

5. The atmospheric humidity change detection device based on infrared digital holography as described in claim 1, characterized in that, The beam splitter I (2) and beam splitter II (13) are germanium beam splitters, silicon beam splitters or glass beam splitters.

6. The atmospheric humidity change detection device based on infrared digital holography as described in claim 1, characterized in that, The beam expander I (4) and beam expander II (5) are germanium beam expanders, silicon beam expanders or glass beam expanders.

7. The atmospheric humidity change detection device based on infrared digital holography as described in claim 1, characterized in that, The sensing band of the infrared CCD (14) includes the infrared laser band.

8. The method of using the atmospheric humidity change detection device based on infrared digital holography as described in any one of claims 1-7, comprising the following steps: S1: Turn on the infrared laser (1). The laser beam is split into an object beam and a reference beam by beam splitter I (2). The object beam passes through the atmospheric environment to be measured. The object beam and the reference beam are superimposed on beam splitter II by using infrared holography. S2: The object beam and the reference beam successfully interfere on the beam splitter II (13) to form a holographic interference pattern, which is recorded by the infrared CCD (14) and transmitted to the computer (15) for storage; S3: The computer (15) performs contrast analysis on the holographic interferograms collected at different time periods, and can determine that the humidity of the atmosphere has changed slightly.

9. The method of using the atmospheric humidity change detection device based on infrared digital holography according to claim 8, characterized in that: The method for contrast analysis of holographic interferograms includes the following steps: S1: Use a CCD to collect the interference pattern of the atmospheric humidity in the object's optical path when the humidity of the target atmosphere remains unchanged, and use Matlab to calculate the holographic fringe contrast; the program automatically selects two pixels of a pair of bright and dark fringes in the fringe pattern whose fringe contrast is closest to 1: these two positions are selected to read the maximum brightness value I. max and minimum brightness value I min The contrast of the stripe pattern was calculated to be (I max -I min ) / (I max + I min ); S2: When the atmospheric humidity changes slightly, the atmosphere absorbs different proportions of infrared light in the object light path, causing the intensity ratio of the object light to the reference light to change. Object and reference lights with different intensity ratios interfere with each other. The reference light path is closed and set to a constant value. The intensity of the object light changes, resulting in simulated interference patterns with different fringe contrasts. The contrast of the changed fringe is calculated. S3: Subtract the changed image contrast from the unchanged image contrast. If the difference is less than the image contrast change range corresponding to the allowable range of atmospheric humidity change, it is considered to have no effect. If the difference is greater than the corresponding image contrast change range, it is considered to have an effect.

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