CN112611464B - Transmission type temperature field measuring device and method based on infrared digital holographic technology - Google Patents
Transmission type temperature field measuring device and method based on infrared digital holographic technology Download PDFInfo
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- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
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- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
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- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
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- G01J5/58—Radiation pyrometry, e.g. infrared or optical thermometry using absorption; using extinction effect
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- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
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Abstract
The invention discloses a transmission type temperature field measuring device and method based on an infrared digital holographic technology, and belongs to the field of infrared digital holographic application. The device comprises an infrared laser, a beam splitter, a beam expander, a lens, a reflector, a temperature field detection cavity, an infrared focal plane array imaging sensor, an image processing unit and a U-shaped opaque shell. The device is protected and fixed by using the U-shaped light-tight shell, and only two lenses III and IV made of germanium are inlaid at the positions of round holes on the device, so that the interference of visible light is avoided, and the purpose of improving the measurement precision is achieved. According to the method, the fringe displacement is calculated by combining the image subtraction with the pixel point size, and the temperature field variation is calculated by the fringe displacement; the infrared digital holographic technology is used for measuring the temperature field, so that the real-time performance of temperature field detection can be ensured, and the resistance of the temperature field detection device to various interferences is improved.
Description
Technical Field
The invention discloses a transmission type temperature field measuring device and method based on an infrared digital holographic technology, and belongs to the field of infrared digital holographic application.
Background
The existing temperature field measuring means mainly comprise four types of probe contact type, schlieren quantitative detection type, infrared thermal imaging detection type and visible light holographic interference detection means, the probe contact type is most commonly used in daily life, the measuring precision is high, the real-time monitoring of the temperature can be realized, the nondestructive detection can not be realized during the measurement, the spatial range of a detectable temperature field is limited, and the method can not be applied to a plurality of industrial fields; the infrared thermal imaging detection formula is to detect the temperature by receiving infrared waves emitted by an object, has high detection speed but limited precision, is easily influenced by the use environment, and can drastically reduce the detection precision when facing the detection environment with smoke or flame, so that the detection method has lower practical application value in industrial production; the schlieren quantitative detection method is simple, but the measurement accuracy is slightly low, and the requirement of high-accuracy temperature field detection cannot be met.
Generally, in the conventional holographic interferometry means, interference fringes are generated by utilizing interference of two beams of coherent light, when physical quantity of an area through which object light passes changes, all changes of the physical quantity are reflected as changes of fringes, and the changes of the fringes are changes of wavelength levels of the light, so that the means can measure very small changes of the physical quantity. When the temperature field changes, the air density changes, the refractive index of the air is changed, the optical path of light propagating in the air is changed by changing the refractive index, after the optical path difference between two beams of coherent light changes, the observed phenomenon is that interference fringes are displaced, and the small change of the temperature field can be calculated by measuring the displacement of the fringes. The holographic interferometry measure is used for measuring the temperature field, so that the device and the method have the advantages of nondestructive detection and high-precision detection, but the temperature field detection device and the method based on the holographic interferometry measure with visible light as a light source have higher requirements on environmental stability and are easily interfered by the visible light due to the wavelength limitation of the visible light; the visible light wavelength is short, the space range of the detectable temperature field is limited, and the range of the detectable temperature field variation is limited; in addition, the detection accuracy is drastically reduced when the detection environment is faced with the presence of smoke or flame, and the detection device cannot be used in a scene requiring darkness; the above-mentioned disadvantages make such temperature field detection means impossible to apply on a large scale.
In order to solve the defects of the technical means, the infrared digital holographic technology is combined with the holographic interferometry means in consideration of various excellent characteristics of the infrared digital holographic, so that the anti-interference performance of the system can be greatly improved, the requirement of the system on stability is reduced, the application range of the system is expanded, and the device and the method for measuring and monitoring the high-precision temperature field in real time, which can be used in multiple scenes, are obtained.
Disclosure of Invention
The invention aims to provide a transmission type temperature field measuring device based on an infrared digital holographic technology, which not only plays the high-precision measurement advantage of a holographic interferometry means, but also combines the advantages of strong infrared digital holographic anti-interference performance and real-time detection.
In order to meet the technical requirements, the technical scheme adopted by the invention is as follows:
a transmission type temperature field measuring device based on an infrared digital holographic technology comprises an infrared laser 1, a beam splitter I2, a beam expander I3, a beam expander II4, a lens I5, a lens II6, a reflecting mirror I7, a reflecting mirror II8, a lens III9, a lens IV10, a beam splitter II11, an infrared focal plane array imaging sensor 12, a microcomputer 13 and a U-shaped opaque shell 14.
The infrared focal plane array imaging sensor 12 is arranged inside a U-shaped opaque casing 14, and the microcomputer 13 is arranged outside the U-shaped opaque casing; the microcomputer 13 is connected with the infrared focal plane array imaging sensor 12 through a data cable; two round holes are formed in the side wall of the U-shaped light-tight shell 14 and used for accommodating a lens III9 and a lens IV10, the connecting line of the center points of the two round holes coincides with the light path of the infrared object beam, and the lens III9 and the lens IV10 are fixed in the round holes in the side wall of the U-shaped light-tight shell; the infrared laser 1 emits infrared laser, the infrared laser is split into two infrared lasers through a beam splitter I2, one infrared laser is collimated into a parallel infrared laser beam through a lens I5 after being expanded through a beam expander I3, the parallel infrared laser beam reaches a reflector I7, then reaches a lens III9 through reflection, and is emitted out of a U-shaped light-tight shell through the lens III9, then reaches a lens IV10, and then enters the U-shaped light-tight shell through the lens IV10, and the beam reaches a beam splitter II11 after passing through the lens IV10, and is called an infrared object beam; a temperature field measurement region is formed between the lens III9 and the lens IV10 along the optical path direction.
The other infrared laser beam split by the beam splitter I2 is collimated by the lens II6 into a parallel infrared laser beam after being expanded by the beam expander II4, and the parallel infrared laser beam reaches the reflector II8 and then reaches the beam splitter II11 after being reflected by the reflector II8, and the beam is called an infrared reference beam.
The infrared object beam and the infrared reference beam form a series of interference fringes, which are called infrared holographic interference patterns, on the beam splitter II11, and the infrared holographic interference patterns are received and recorded by the infrared focal plane array imaging sensor 12, and the received optical signals are converted into electrical signals, and then the electrical signals are transmitted to the microcomputer 13 for storage and data processing.
The infrared laser 1 selects an infrared laser with the laser emission wavelength of 10.64 mu m, and the infrared laser beam with the wavelength has weak attenuation effect in the air, so that the infrared laser beam can be prevented from being attenuated too fast in the air; meanwhile, the infrared laser beam with the wavelength is different from the infrared light with the wavelength of 780-7000 nm emitted by the flame, and the influence of the infrared light emitted by the flame on the interference pattern can be removed by means of image processing, so that the device can accurately measure the temperature field distribution of the flame.
Furthermore, according to the infrared laser 1 disclosed by the invention, the infrared laser with the laser emission wavelength of 10.64 mu m is selected, so that the penetrability of an object light beam and a reference light beam to a particle field such as smoke is greatly improved compared with that of a laser beam using a visible light wave band, and the device can accurately measure the temperature field distribution in an environment with the particle field such as smoke.
The inner side of the side wall of the U-shaped opaque housing 14 is pure black to absorb the infrared light entering the U-shaped opaque housing 14, so as to prevent the infrared light from being reflected back and forth in the U-shaped opaque housing 14 and being received by the infrared focal plane array imaging sensor 12 to influence the receiving of the interference fringe pattern by the infrared focal plane array imaging sensor 12.
The lens III9 and the lens IV10 are made of germanium materials, so that visible light is prevented from entering an optical path to influence interference patterns.
The infrared object beam and the infrared reference beam are parallel light after beam expansion, and the maximum difference of the optical paths of the infrared object beam and the infrared reference beam is 1cm.
The infrared focal plane array imaging sensor 12 is used for receiving the infrared holograms, the sensitivity of the infrared focal plane array imaging sensor 12 is selected and matched with the power of the infrared laser 1, and the sensing wave band is required to be matched with the wavelength of the infrared laser 1, namely, the wave band of the wavelength of the selected infrared laser 1 can be sensed, so that a good imaging effect is achieved.
The infrared focal plane array imaging sensor 12 is replaced by a CCD image sensor with an induction wave band containing the wave band of the infrared laser 1, and the function realization of the whole device is not affected.
The microcomputer 13 can filter the received infrared hologram and redisplay the processed hologram so that the device can measure the temperature field distribution of flame and the temperature field distribution in the environment with particle fields such as smoke.
The transmission type temperature field measuring method based on infrared digital holographic technology relies on the basic theory of holographic interference measurement, and according to the phenomenon that the tiny change of the temperature field can cause the interference fringe to displace, the displacement of the fringe is calculated, so that the change value of the temperature field can be calculated, and the method comprises the following steps:
(1) The infrared laser 1 is turned on, the interference pattern generated on the time division beam mirror II11 at this time is collected with the CCD image sensor, and the collected interference pattern, which is called an initial temperature field infrared hologram, is stored in the microcomputer.
(2) Placing a desired measurement temperature field region in a recessed region of a U-shaped opaque housing (14) between lens III9 and lens IV10, and leaving the desired measurement temperature field region in the optical path; in general, since the optical path employed is a transmissive optical path, the desired measurement temperature field region is required to be transparent.
(3) After the object to be measured is stabilized, the interference pattern generated on the time division beam mirror II11 is collected by a CCD image sensor, and the collected interference pattern is stored in a microcomputer, and is called a temperature field infrared hologram after change.
(4) And performing image subtraction processing on the initial temperature field infrared hologram and the temperature field infrared hologram after the change, and calculating the displacement d of each interference fringe in the infrared holograms before and after the change of the temperature field.
(5) The fringe order N of each interference fringe is calculated from the obtained fringe displacement d.
(6) And combining the relation between the gas refractive index and the gas density described by the obtained fringe interference order N combined with the Grade-Dall relation with an ideal gas state equation to obtain a mathematical relation formula of temperature and fringe order, obtaining the temperature of each point through mathematical calculation, and reconstructing the temperature field distribution of a temperature field measurement area by integrating the temperature information of each point.
Further, the steps 3 to 6 are repeatedly executed to realize real-time monitoring of the temperature field.
Furthermore, the area of the temperature field to be measured in the step 2 may be the inside of the non-solid transparent object such as air, or may be the area above the surface of the solid object; when the desired temperature field region contains a physical object, the physical object may not block the propagation of the infrared object beam.
Further, in step 3, when the object to be measured in the temperature field measurement area is flame, the collected interference pattern needs to be filtered, and the adopted filter is a band-pass filter, so that the influence of infrared light emitted by the flame on the interference pattern is eliminated.
Further, in step 1 and step 3, when smoke exists in the temperature field measurement area, the collected interference pattern needs to be filtered, and the adopted filter is a low-pass filter, so that image noise formed by the smoke is removed.
Further, in step 4, the displacement d of the interference fringes at each point in the infrared hologram before and after the temperature field change is calculated by counting the number of pixels moved by the fringes and combining the width of each pixel.
Compared with the prior art, the invention has the following advantages:
(1) Compared with the traditional temperature field measurement by using the visible light digital holographic interferometry, the infrared digital holographic measurement system has the advantages that the infrared light wavelength is longer than the visible light wavelength, so that the whole temperature field measurement system can realize normal measurement of the temperature field under larger vibration amplitude, and the requirement of the system on environmental stability is reduced.
(2) Compared with the traditional temperature field measurement by using a visible light digital holographic interferometry means, the infrared digital holographic temperature field measurement device and method provided by the invention have the advantage that the infrared digital holographic technology is applied to the transmission type temperature field measurement, and the infrared light has far stronger penetrability to the particle fields such as smoke and the like than the visible light, so that the temperature field measurement device and method provided by the invention can realize accurate measurement to the temperature field in the environment with the particle fields such as smoke and the like as interference.
(3) Compared with the traditional temperature field measurement by using a visible light digital holographic interferometry means, the infrared digital holographic measurement device uses infrared light with the wavelength of 10.64 mu m as a light source, is different from infrared light with the wavelength of 780nm-7000nm emitted by flame, and can remove the influence of infrared light emitted by flame on interference patterns by means of image processing, so that the device can more accurately measure the temperature field distribution of flame.
(4) According to the transmission type temperature field measuring device based on the infrared digital holographic technology, the whole device is protected and fixed by the U-shaped opaque shell, the inner side of the side wall of the used U-shaped opaque shell is pure black, and only two lenses lll and IV made of germanium are inlaid at the positions of round holes on the device, so that interference of visible light is avoided, and the temperature field measuring precision is improved.
(5) The invention relates to a transmission type temperature field measuring method based on an infrared digital holographic technology, which adopts an image subtraction method to process an initial temperature field infrared hologram and a changed temperature field infrared hologram, takes the number of pixel points as a basic unit of displacement of stripes, and can quickly calculate the displacement of the stripes by combining the size of the pixel points, and reconstruct temperature field distribution according to the displacement of the stripes; compared with the prior algebraic reconstruction method and other temperature field reconstruction methods, the method has the advantages of small operand and high temperature field reconstruction speed.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
fig. 1 is a schematic overall structure of an embodiment of the present invention:
in the figure: 1-infrared laser, 2-beam splitter I, 3-beam expander I, 4-beam expander II, 5-lens I, 6-lens II, 7-mirror I, 8-mirror II, 9-lens III, 10-lens IV, 11-beam splitter II, 12-infrared focal plane array imaging sensor, 13-microcomputer and 14-opaque shell.
Fig. 2 is a schematic three-dimensional shape of a U-shaped opaque housing according to an embodiment of the invention.
Fig. 3 is a schematic of the workflow of the present invention.
Fig. 4 is a diagram showing the relative positions of a planar heating plate as a measured object and an infrared object beam in embodiment 3 of the present invention, wherein the arrow line is a schematic representation of the bottom of the propagation range of the infrared object beam, and the arrow direction represents the propagation direction of the infrared object beam, and the three-dimensional coordinate is an indication mark of the three-dimensional direction.
FIG. 5 is an example of an initial temperature field infrared hologram recorded in operation 1 of example 3 of the present invention.
Fig. 6 is an example of the temperature field infrared hologram after change recorded in operation 3 in example 3 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the scope of the present invention is not limited to the above.
Example 1
As shown in fig. 1, the present embodiment provides a transmission type temperature field measurement device based on an infrared digital holographic technology, which includes an infrared laser 1, a beam splitter I2, a beam expander I3, a beam expander II4, a lens I5, a lens II6, a reflector I7, a reflector II8, a beam splitter II11, an infrared focal plane array imaging sensor 12, and a U-shaped opaque housing 14, wherein a microcomputer 13 is disposed outside the U-shaped opaque housing and connected with the infrared focal plane array imaging sensor 12 through a data cable, and a lens III9 and a lens IV10 are disposed on the side wall of the U-shaped opaque housing.
The infrared laser 1 selects an infrared laser with the laser emitting wavelength of 10.64 mu m, the attenuation effect of the infrared laser beam with the wavelength in the air is weak, the infrared laser beam can be prevented from being attenuated too fast in the air, meanwhile, the wavelength of the infrared laser beam is different from the wavelength of infrared light with the wavelength of 780nm-7000nm emitted by the flame, and the influence of the infrared light emitted by the flame on the interference pattern can be removed by an image processing method, so that the device can accurately measure the temperature field distribution of the flame. The infrared laser 1 emits infrared laser, the infrared laser is split into two infrared lasers through a beam splitter I2, one infrared laser is collimated into a parallel infrared laser beam through a lens I5 after being expanded through a beam expander I3, the parallel infrared laser beam reaches a reflector I7, then reaches a lens III9 after being reflected, and is emitted out of a U-shaped light-tight shell through the lens III9, then reaches a lens IV10, and then enters the U-shaped light-tight shell through the lens IV10, and the beam reaches a beam splitter II11 after passing through the lens IV10, wherein the beam is called an infrared object beam; the other infrared laser beam split by the beam splitter I2 is collimated by the lens II6 into a parallel infrared laser beam after being expanded by the beam expander II4, the parallel infrared laser beam reaches the reflector II8 and then reaches the beam splitter II11 after being reflected by the reflector II8, and the beam is called an infrared reference beam; a temperature field measuring area is arranged between the lens III9 and the lens IV10 along the direction of the light path; the infrared object beam and the infrared reference beam form a series of interference fringes, called an infrared holographic interference pattern, on a beam splitter II11, which is received and recorded by an infrared focal plane array imaging sensor 12.
The sensitivity of the infrared focal plane array imaging sensor 12 is selected to be matched with the power of the infrared laser 1, and the sensing wave band of the sensor needs to be matched with the wavelength of the infrared laser 1, namely, the wave band of the wavelength of the selected infrared laser 1 can be sensed, so that a better imaging effect is achieved. The infrared focal plane array imaging sensor 12 converts the received optical signals into electrical signals, which are then transmitted to a microcomputer for storage and data processing. To this end, temperature information of the measured temperature field is stored in the microcomputer.
The infrared laser 1, the beam splitter I2, the beam expander I3, the beam expander II4, the lens I5, the lens II6, the reflector I7, the reflector II8, the beam splitter II11 and the infrared focal plane array imaging sensor 12 are fixed in the U-shaped opaque shell 14, so that the stability of the device is enhanced, and the imaging quality is ensured.
The infrared laser 1 is of the type CO2-ULR-75, the infrared focal plane array imaging sensor 12 is of the type cube817, and the lens III9 and the lens IV10 are germanium lenses.
The inner side of the side wall of the U-shaped opaque housing 14 is pure black to absorb the infrared light entering the U-shaped opaque housing 14, so as to prevent the infrared light from being reflected back and forth inside the U-shaped opaque housing 14 and being received by the infrared focal plane array imaging sensor 12, thereby affecting the receiving of the interference fringe pattern by the infrared focal plane array imaging sensor 12.
The infrared focal plane array imaging sensor 12 described in the present embodiment may also be replaced with a CCD image sensor whose sensing band includes the wavelength band of the infrared laser 1.
Example 2
The example provides a transmission type temperature field measurement method based on an infrared digital holographic technology, which specifically comprises the following steps:
step 1: the infrared laser 1 is turned on, the interference pattern generated on the time division beam mirror II11 at this time is collected with the CCD image sensor, and the collected interference pattern, which is called an initial temperature field infrared hologram, is stored in the microcomputer.
Step 2: the desired measurement temperature field area is placed in the recessed area of the U-shaped opaque housing 14 between lens III9 and lens IV10 and is in the optical path, which in this embodiment is measured by the temperature field distribution of the air in the temperature field measurement area and its small variations in temperature.
Step 3: after the temperature field area to be measured is stable, the interference pattern generated on the time division beam mirror II11 is acquired by a CCD image sensor, and the acquired interference pattern is stored in a microcomputer and is called a changed temperature field infrared hologram.
Step 4: and performing image subtraction processing on the initial temperature field infrared hologram and the temperature field infrared hologram after the change, and calculating the displacement d of each interference fringe in the infrared holograms before and after the change of the temperature field.
Step 5: the fringe order N of each interference fringe is calculated from the obtained fringe displacement d.
The method for calculating the fringe order N is as follows:
taking a certain stripe as an example, when the stripe interval in the initial temperature field infrared hologram is x, the stripe order N, the stripe displacement d and the stripe interval x in the initial temperature field infrared hologram satisfy the relation: n=d/x. Since the fringe spacing x and the fringe displacement d in the initial temperature field infrared hologram can be calculated by counting the number of pixels and combining the width of each pixel, the fringe order N can be obtained by the relational expression.
Step 6: and calculating the density field of a temperature field measurement area according to the relation between the gas refractive index and the gas density described by combining the obtained fringe interference order N with the Grade St-Del relation, calculating the temperature of each point according to an ideal gas state equation, and reconstructing the temperature field distribution of air in the temperature field measurement area according to the temperature information of each point.
The method for calculating the temperature of each point is as follows:
the relationship between gas refractive index and gas density described by the gladeston-dil relationship is:
the ideal gas state equation is:
the combination of the two formulas can obtain a relation between the refractive index and the temperature:
through mathematical calculation, the mathematical relationship between temperature and the fringe order N can be obtained:
wherein K is the fringe order, mu is the air molar mass, R is the gas universal constant, P is the gas pressure, T0 is the ambient temperature of the environment where the device is located, lambda is the wavelength of light waves, and N is the fringe order obtained in step 5; to this end, the temperature can be calculated.
Further, the steps 3 to 6 are repeatedly executed to realize real-time monitoring of the temperature field.
Further, the minute changes of the air temperature values at all positions in the temperature field detection area within a certain time range can be obtained by comparing the temperature field distribution within different time.
Further, when the measured object placed in the opaque housing 14 in step 2 is a non-transparent solid object, the measured object may not block the propagation of the infrared object beam, in which case only the temperature field distribution above the object surface may be measured.
Further, in step 3, when the object to be measured in the temperature field measurement area is flame, the collected interference pattern needs to be filtered, and the adopted filter is a band-pass filter, so that the influence of infrared light emitted by the flame on the interference pattern is eliminated.
Further, in step 1 and step 3, when smoke exists in the temperature field measurement area, although the infrared light has strong penetrability to particle fields such as smoke, the situation that the infrared light is blocked by the particle fields and the temperature field cannot be measured cannot occur, the particle fields are recorded together with the interference patterns as image noise, the acquired interference patterns need to be filtered, and the adopted filter is a low-pass filter, so that the image noise formed by the smoke is removed.
Example 3
According to the transmission type temperature field measuring device based on the infrared digital hologram technology and the transmission type temperature field measuring method based on the infrared digital hologram technology provided in the embodiment 1 and the embodiment 2, the temperature field distribution above the surface of a planar heating plate is measured. The planar heating plate is placed in the temperature field measurement area as required in the foregoing description, and does not block the propagation of the infrared object beam, and as shown in fig. 3, the upper surface of the planar heating plate is tangent to the bottom of the propagation range of the infrared object beam.
The specific measurement steps are as follows:
step 1: the infrared laser 1 is turned on, an initial temperature field infrared hologram generated on the time division beam mirror II11 is collected with a CCD image sensor, and the collected interference pattern is stored in a microcomputer.
Step 2: the planar heating plate in the heated state is placed in the recessed area of the U-shaped opaque housing 14 between lens III9 and lens IV10, with the upper surface of the planar heating plate tangential to the bottom of the infrared object beam propagation range.
Step 3: after the whole device is stable, the CCD image sensor is used for collecting the infrared hologram of the temperature field after the change generated on the time division beam splitter II11, and the collected interference pattern is stored in the microcomputer.
Step 4: and performing image subtraction processing on the initial temperature field infrared hologram and the temperature field infrared hologram after the change, and calculating the displacement d of each interference fringe in the infrared holograms before and after the change of the temperature field.
Step 5: the fringe order N of each interference fringe is calculated from the obtained fringe displacement d.
Step 6: and calculating the density field of a temperature field measurement area according to the relation between the gas refractive index and the gas density described by combining the obtained fringe interference order N with the Grade St-Del relation, calculating the temperature of each point according to an ideal gas state equation, and reconstructing the temperature field distribution of air in the temperature field measurement area according to the temperature information of each point.
Furthermore, in the whole temperature field measurement process, the steps 3 to 6 are automatically repeated, so that the temperature field above the upper surface of the planar heating plate in the heating state is monitored in real time.
FIG. 5 is an example of an initial temperature field infrared hologram recorded in operation 1 of example 3 of the present invention.
Fig. 6 is an example of the temperature field infrared hologram after change recorded in operation 3 in example 3 of the present invention.
As can be seen from comparing fig. 5 with fig. 6, when a planar heating plate in a heating state is placed in the temperature field measurement area, each interference fringe is obviously displaced, at this time, any point on the fringe in fig. 6 can be selected, compared with fig. 5, the fringe displacement of the point is obtained by counting the pixel points, the current temperature value of the point is calculated according to the methods from step 4 to step 6, and the same method can be applied to the calculation of the temperature value of any point on fig. 6 as an example, so as to realize the measurement of the whole temperature field in the area photographed by fig. 6.
Steps 4 to 6 are implemented by running a self-programming program in the microcomputer 13, and the specific implementation method of embodiment 2 is described in detail, so that a repeated description will not be made.
Claims (9)
1. A transmission type temperature field measuring device based on infrared digital holographic technology is characterized in that: the infrared laser comprises an infrared laser (1), a beam splitter I (2), a beam expander I (3), a beam expander II (4), a lens I (5), a lens II (6), a reflector I (7), a reflector II (8), a lens III (9), a lens IV (10), a beam splitter II (11), an infrared focal plane array imaging sensor (12), a microcomputer (13) and an opaque shell (14);
the infrared focal plane array imaging sensor (12) is arranged inside the U-shaped opaque casing (14), and the microcomputer (13) is arranged outside the U-shaped opaque casing; the microcomputer (13) is connected with the infrared focal plane array imaging sensor (12) through a data cable; two round holes are formed in the side wall of the U-shaped light-tight shell (14) and used for accommodating a lens III (9) and a lens IV (10), the connecting line of the center points of the two round holes coincides with the light path of the infrared object beam, and the lens III (9) and the lens IV (10) are fixed in the round holes in the side wall of the U-shaped light-tight shell;
the infrared laser (1) emits infrared laser, the infrared laser is split into two infrared lasers through a beam splitter I (2), one infrared laser is collimated into a parallel infrared laser beam through a lens I (5) after being expanded through a beam expander I (3), the parallel infrared laser beam reaches a reflector I (7), then reaches a lens III (9) through reflection, is emitted out of a U-shaped opaque shell through the lens III (9), then reaches a lens IV (10), then enters the U-shaped opaque shell through the lens IV (10), and reaches a beam splitter II (11) after passing through the lens IV (10), and the beam is called an infrared object beam; a temperature field measuring area is arranged between the lens III (9) and the lens IV (10) along the light path direction;
the other infrared laser beam split by the beam splitter I (2) is collimated into a parallel infrared laser beam by the lens II (6) after being expanded by the beam expander II (4), and the parallel infrared laser beam reaches the reflector II (8) and then reaches the beam splitter II (11) after being reflected by the reflector II (8), and is called as an infrared reference beam;
the infrared object beam and the infrared reference beam form a series of interference fringes on a beam splitter II (11), the series of interference fringes are called infrared holographic interference patterns, the infrared holographic interference patterns are received and recorded by an infrared focal plane array imaging sensor (12), the received optical signals are converted into electric signals, and the electric signals are transmitted to a microcomputer (13) for storage and data processing;
the infrared object beam and the infrared reference beam are parallel light after beam expansion, and the maximum difference of the optical paths of the infrared object beam and the infrared reference beam is 1cm.
2. The infrared digital holography-based transmission type temperature field measuring device according to claim 1, wherein: the infrared laser (1) is an infrared laser with the laser emitting wavelength of 10.64 mu m.
3. The infrared digital holography-based transmission type temperature field measuring device according to claim 1, wherein: the lens III (9) and the lens IV (10) are germanium lenses; the inner side of the side wall of the U-shaped opaque outer shell (14) is pure black.
4. The infrared digital holography-based transmission type temperature field measuring device according to claim 1, wherein: the infrared focal plane array imaging sensor (12) is replaced by a CCD image sensor with an induction wave band comprising the wavelength band of the infrared laser (1).
5. A method for measuring a temperature field using the device according to any one of claims 1 to 4, comprising the steps of:
(1) Turning on an infrared laser (1), collecting an interference pattern generated on a time division beam splitter II (11) by using a CCD image sensor or an infrared focal plane array imaging sensor (12), and storing the collected interference pattern in a microcomputer, wherein the interference pattern is called an initial temperature field infrared hologram;
(2) Placing a desired measurement temperature field region in a recessed region of a U-shaped opaque housing (14) between lens III (9) and lens IV (10) and leaving the desired measurement temperature field region in the optical path;
(3) After the temperature field area to be measured is stable, acquiring an interference pattern generated on a time division beam splitter II (11) by using a CCD image sensor or an infrared focal plane array imaging sensor (12), and storing the acquired interference pattern in a microcomputer, wherein the interference pattern is called a changed temperature field infrared hologram;
(4) Performing image subtraction processing on the initial temperature field infrared hologram and the temperature field infrared hologram after the change, and calculating the displacement d of each interference fringe in the infrared holograms before and after the change of the temperature field;
(5) Calculating the fringe order N of each interference fringe according to the obtained fringe displacement d;
(6) And combining the relation between the gas refractive index and the gas density described by the obtained fringe interference order N combined with the Grade-Dall relation with an ideal gas state equation to obtain a mathematical relation formula of temperature and fringe order, obtaining the temperature of each point through mathematical calculation, and reconstructing the temperature field distribution of a temperature field measurement area by integrating the temperature information of each point.
6. The method according to claim 5, wherein: and (3) repeatedly executing the steps (3) to (6) to realize real-time monitoring of the temperature field.
7. The method according to claim 5, wherein: in the step (3), when the object to be measured in the temperature field measurement area is flame, filtering processing is required to be carried out on the acquired interference pattern, and the adopted filter is a band-pass filter, so that the influence of infrared light emitted by the flame on the interference pattern is eliminated.
8. The method according to claim 5, wherein: in the step (1) and the step (3), when smoke exists in the temperature field measurement area, the acquired interference pattern is subjected to filtering treatment, and the adopted filter is a low-pass filter, so that image noise formed by the smoke is removed.
9. The method according to claim 5, wherein: the method for calculating the displacement d of the interference fringes of each point in the infrared hologram before and after the temperature field changes is as follows: the displacement d of the interference fringes is calculated by counting the number of pixels in which the fringes move and combining the width of each pixel.
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| CN108732903A (en) * | 2018-05-08 | 2018-11-02 | 昆明理工大学 | A kind of scene of a fire search and rescue device based on infrared holographic technique |
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| CN110045587A (en) * | 2019-03-13 | 2019-07-23 | 昆明理工大学 | It is a kind of to be used for the device that the scene of a fire is searched and rescued based on optical fiber infrared holography |
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| CN108732903A (en) * | 2018-05-08 | 2018-11-02 | 昆明理工大学 | A kind of scene of a fire search and rescue device based on infrared holographic technique |
| CN108917943A (en) * | 2018-08-14 | 2018-11-30 | 岭南师范学院 | A kind of flame temperature field measurement device and method based on projection background stration technique |
| CN110045587A (en) * | 2019-03-13 | 2019-07-23 | 昆明理工大学 | It is a kind of to be used for the device that the scene of a fire is searched and rescued based on optical fiber infrared holography |
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