CN108981822B - Reflected light elimination method for temperature deformation synchronous measurement - Google Patents

Reflected light elimination method for temperature deformation synchronous measurement Download PDF

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CN108981822B
CN108981822B CN201810986688.3A CN201810986688A CN108981822B CN 108981822 B CN108981822 B CN 108981822B CN 201810986688 A CN201810986688 A CN 201810986688A CN 108981822 B CN108981822 B CN 108981822B
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pixel point
intensity
temperature
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CN108981822A (en
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冯雪
唐云龙
岳孟坤
方旭飞
屈哲
朱相宇
李燕
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Tsinghua University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D21/00—Measuring or testing not otherwise provided for
    • G01D21/02—Measuring two or more variables by means not covered by a single other subclass
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
    • G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure
    • G01D3/036—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure on measuring arrangements themselves

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Abstract

The present disclosure relates to a reflected light elimination method for temperature deformation synchronous measurement, which comprises the steps of obtaining the initial temperature of a reference point of a measured piece and the initial light intensity of the reference point; heating the tested piece; collecting an image of a detected piece, and determining first radiant light intensity of pixel points on the image; calculating the first temperature of the pixel point and the radiation intensity of the blue light channel according to the first radiation intensity of the pixel point, the initial temperature of the reference point and the initial light intensity; determining the reflected light intensity of a blue light channel of a pixel point; correcting the first radiant intensity of the pixel point to obtain the corrected radiant intensity of the pixel point; calculating a second temperature of the pixel point according to the corrected radiation intensity of the pixel point, the corrected radiation intensity of the reference point and the initial temperature; and if the difference value of the second temperature and the first temperature of each pixel point meets the convergence condition, determining the second temperature of each pixel point as the temperature of the surface of the measured piece. The influence of reflected light can be effectively eliminated, and the measurement precision is improved.

Description

Reflected light elimination method for temperature deformation synchronous measurement
Technical Field
The disclosure relates to the technical field of measurement, in particular to a reflected light elimination method for synchronous measurement of temperature deformation.
Background
By using the CCD camera and through reasonable light path, light source and filter design, the reflected light and the radiated light on the surface of the object can be respectively received and processed. The radiation reflects the temperature of the object and is used to calculate the temperature field of the object. The reflected light reflects the topography of the object surface for calculating the displacement and deformation fields of the object.
At present, the temperature of a high-temperature environment actually tested is generally below 3000K, and according to the blackbody radiation theory, the radiation energy at the moment is strongest in a red light channel (R) wave band, second in a green light channel (G) and weakest in a blue light channel (B) in a visible light region. Therefore, a blue light channel is selected as a reflection light channel for testing displacement and deformation fields, a red light channel and a green light channel are respectively used as radiation light channels, and a red light channel and a green light channel are combined for testing temperature fields. Compared with a red light channel and a green light channel, the infrared emission temperature control method has the advantages that by adopting the colorimetric temperature measurement principle, under the condition that the emissivity of the material is approximate and the wavelength is irrelevant, the influence of the emissivity changing along with the temperature can be eliminated, and the relation between the emissivity of the material of the object and the temperature is corrected. The blue light source is selected as the light source for synchronously measuring temperature deformation in a high-temperature environment, so that the influence of the blue light source on radiation temperature measurement is avoided.
The principle of colorimetric thermometry is derived based on the ideal situation where there is no reflected light at all, which is present in the actual environment. When reflected light is present, the reflected light needs to be superimposed for calculation. Although the influence of the reflected light can be eliminated by using the brightness of the initially recorded image as the reflected light and subtracting the brightness of the initially recorded image from the brightness of the subsequent image, the reflected light cannot be eliminated well due to the correlation between the reflectivity of the object material and the temperature, resulting in inaccurate calculation results.
Disclosure of Invention
In view of this, the present disclosure provides a reflected light elimination method for temperature-deformation synchronous measurement, which can effectively eliminate the influence of reflected light in the temperature-deformation synchronous measurement, correct the result of the temperature-deformation synchronous measurement, and improve the precision of the temperature-deformation synchronous measurement.
According to an aspect of the present disclosure, a reflected light elimination method for synchronous measurement of temperature deformation is provided, the method including:
step 1, before heating a measured piece, acquiring an initial temperature T of a reference point of the measured piece0And an initial light intensity (B) of a reference point of the measured objectR0，BG0，BB0) Wherein B isR0Representing the initial intensity of the red channel, BG0Representing the initial intensity of the green channel, BB0Representing the initial light intensity of the blue channel;
step 2, heating the tested piece;
step 3, collecting the image of the tested piece, and determining the first radiant intensity (B) of each pixel point on the image according to the imageR1，BG1) Wherein B isR1、BG1Respectively after heating the measured objectThe radiation intensity of the red light channel and the radiation intensity of the green light channel of the pixel point;
step 4, aiming at each pixel point on the image, according to the first radiation intensity (B) of the pixel pointR1，BG1) And the initial temperature T of the reference point0Initial light intensity (B)R0，BG0，BB0) Calculating the first temperature T1 of the pixel point and the radiation intensity B of the blue light channel by using the temperature measurement principle of the enhanced colorimetryB1Wherein B isB1The radiation intensity of the blue light channel of the pixel point is the radiation intensity of the blue light channel after the tested piece is heated;
and 5, aiming at each pixel point on the image, according to the light intensity relation of the blue light channel and B of the pixel pointB1Determining the reflected light intensity B of the blue light channel of the pixel pointref；
Step 6, aiming at each pixel point on the image, and according to B of the pixel pointrefCorrecting the B of the pixel pointR1、BG1Obtaining the corrected radiation intensity B of the red light channel and the green light channel of the pixel pointR1' and BG1’；
Step 7, aiming at each pixel point on the image, according to the corrected radiation intensity of the pixel point, the corrected radiation intensity of the reference point and T0Calculating a second temperature T2 of the pixel point by using an enhanced colorimetric temperature measurement principle;
and 8, if the difference value of the T2 and the T1 of each pixel point meets the convergence condition, determining the T2 of each pixel point as the temperature of the surface of the tested piece.
In one possible implementation, the method further includes:
if the difference value between T2 and T1 of any pixel point does not meet the convergence condition, the corrected radiation intensity (B) of the reference point is usedR0’，BG0') and the radiation intensity B of the blue light channelB0' initial radiation intensity determined as a reference point, corrected radiation intensity (B) of each pixel point on the imageR1’，BG1') determines the first radiation intensity for each pixel point and returns to step 4.
In one possible implementation, step 4 includes:
aiming at each pixel point on the image, and according to B of the pixel pointR1And BG1Initial light intensity of reference point BR0And BG0And T0Calculating the first temperature T1 of the pixel point by using the temperature measurement principle of the enhanced colorimetry;
for each pixel point on the image, according to T0、BR0、BB0And B of the pixel pointR1The first temperature T1, the radiation intensity B of the blue light channel of the pixel point is calculated by utilizing the temperature measurement principle of the enhanced colorimetryB1。
In a possible implementation manner, the step 5 is performed according to the relationship between the light intensity of the blue light channel and the B of the pixel pointB1Determining the reflected light intensity B of the blue light channel of the pixel pointrefThe method comprises the following steps:
the total light intensity B of the blue light channel of the pixel pointtolWith the intensity of radiation BB1The difference of the two is used as the reflected light intensity B of the blue light channel of the pixel pointref。
In one possible implementation, the method further includes:
the influence coefficient of the blue light channel on the radiation light of the red light channel K1 and the influence coefficient of the radiation light of the green light channel K2 on the image are obtained.
In a possible implementation manner, the step 6 is based on the B of the pixel pointrefCorrecting the B of the pixel pointR1、BG1Obtaining the corrected radiation intensity B of the red light channel and the green light channel of the pixel pointR1' and BG1', includes:
according to the reflected light intensity B of the blue light channel of the pixel pointrefAnd K1 correcting B of the pixel pointR1Obtaining the corrected radiation intensity B of the red light channel of the pixel pointR1’；
According to the reflected light intensity B of the blue light channel of the pixel pointrefAnd K2 correcting B of the pixel pointG1Obtaining the corrected radiation intensity B of the green light channel of the pixel pointG1’。
In one possible implementation, step 8 includes:
and when the average value of the difference values of T2 and T1 of all the pixel points meets the convergence condition, determining the T2 of each pixel point as the temperature of the surface of the measured piece.
In one possible implementation, step 8 includes:
and when the maximum value of the absolute values of the difference values of the T2 and the T1 of all the pixel points meets the convergence condition, determining the T2 of each pixel point as the temperature of the surface of the measured piece.
Acquiring an image of a heated measured piece obtained by collecting the image, calculating the radiant light intensity of a red light channel and the radiant light intensity of a green light channel of each pixel point on the image, and calculating the first temperature of each pixel point and the radiant light intensity of the blue light channel by combining the initial light intensity and the initial temperature of a reference point and utilizing an enhanced colorimetry temperature measurement principle; then the reflected light intensity of the blue light channel can be obtained according to the light intensity relation of the blue light channel, so that the radiation light intensity of the pixel point can be corrected according to the calculated reflected light intensity of the blue light channel, and the influence of the reflected light on the measurement result can be effectively eliminated.
And calculating to obtain a second temperature according to the corrected radiation intensity, and determining the second temperature of each pixel point as the temperature of the surface of the measured piece under the condition that the difference value between the second temperature and the first temperature of each pixel point meets the convergence condition.
According to the reflected light elimination method for temperature deformation synchronous measurement, the influence of reflected light in the temperature deformation synchronous measurement can be effectively eliminated, the result of the temperature deformation synchronous measurement is corrected, and the precision of the temperature deformation synchronous measurement is improved.
Other features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments, features, and aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.
Fig. 1 shows a schematic structural diagram of a temperature deformation synchronous measurement system according to an embodiment of the present disclosure.
Fig. 2 shows a flowchart of a reflected light elimination method for temperature deformation simultaneous measurement according to an embodiment of the present disclosure.
Fig. 3 shows a flowchart of a reflected light elimination method for temperature deformation simultaneous measurement according to an embodiment of the present disclosure.
Fig. 4A is a graph showing the result of non-elimination of reflected light in an exemplary temperature deformation synchronization measurement.
Fig. 4B is a diagram illustrating the result of eliminating reflected light in the temperature deformation synchronization measurement according to an example of the present disclosure.
Fig. 5 shows a schematic diagram of the results of a simultaneous measurement of temperature deformation according to an example of the present disclosure.
Detailed Description
Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present disclosure. It will be understood by those skilled in the art that the present disclosure may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present disclosure.
Fig. 1 shows a schematic structural diagram of a temperature-deformation synchronous measurement system according to an embodiment of the present disclosure.
As shown in fig. 1, the system may include: the device comprises a tested piece 1, an experiment chamber 2, a wind tunnel observation window 3, a photosensitive lens 4, a filter 5, an image acquisition unit 6, a blue light source 7, an infrared thermometer 8, a synchronous control device 9 and an image processing unit 10.
The blue light source 7 is electrically connected with the synchronous control device 9, the image acquisition unit 6 and the infrared thermometer 8 are respectively electrically connected with the synchronous control device 9 through signal lines, and the synchronous control device 9 is electrically connected with the image processing unit 10. The filter 5 and the photosensitive lens 4 are arranged in sequence in front of the image acquisition unit 6. The blue light source 7 provides an illumination light source for the tested piece 1 in the experiment chamber 2 through the wind tunnel observation window 3. The image acquisition unit 6 acquires the image of the measured piece 1 through the wind tunnel observation window 3, and the infrared thermometer 8 acquires the temperature data of the measured piece 1 through the wind tunnel observation window 3.
The tested piece 1 may be made of a thermal protection material, such as a silicon carbide material, a modified carbon/carbon material, or the like. The object 1 to be measured can be made into a flat plate, and the shape of the flat plate can be rectangular, square and the like.
The experiment chamber 2 can be arranged in an electric arc wind tunnel and is used for the ablation experiment of the tested piece 1. The high-pressure airflow can be heated by the electric arc heater during the operation of the electric arc wind tunnel, and is expanded and accelerated by the spray pipe to form high-temperature jet flow, so that the ablation test is performed on a tested piece arranged in the experiment cabin at the outlet of the spray pipe. The temperature in the experiment chamber 2 can be 700-2600 ℃, and can be used for synchronously measuring the temperature deformation of the tested piece 1 in a high-temperature environment.
The wind tunnel observation window 3 can be arranged on the wall of the experiment chamber 2, and the related data of the tested piece 1 can be collected through the wind tunnel observation window 3. One or more wind tunnel observation windows 3 may be installed, and the shape of the wind tunnel observation window 3 may be rectangular, circular, and the like, and for example, may be circular, which enables the light received by the object 1 to be more uniform.
The photosensitive lens 4 may be a component in the image capturing unit 6, and may record light changes and convert the light into an electrical signal to be transmitted to the image capturing unit 6.
The filter 5 may be installed between the photosensitive lens 4 and the image pickup unit 6. The filter 5 can be used for filtering the light of the red light wave band and the green light wave band, so that most of red light and green light are attenuated, and the light of the blue light wave band can be completely passed through, therefore, the influence of reflected light caused by the red light and the green light on the deformation data of the tested piece 1 can be reduced, and the precision of the deformation data of the tested piece 1 is improved. The image acquisition unit 6 may be configured to process (e.g., analog-to-digital convert, store, etc.) the received electrical signals to obtain an image of the object 1. The image acquisition unit 6 may be a CMOS camera, a CCD camera, or the like.
The blue light source 7 may refer to a light source capable of emitting electromagnetic waves having a wavelength between 400nm and 450nm, for example: LED blue light lamps, etc. The blue light source 7 can be used as a light source for synchronous measurement of temperature deformation, and can avoid the influence of radiation light on the test temperature as much as possible.
The infrared thermometer 8 can be used to obtain the temperature of the piece 1 under test. The infrared thermometer 8 can accurately measure its surface temperature by measuring the infrared energy radiated from the object itself. The infrared thermometer 8 may be a point thermometer, a thermal infrared imager, or the like.
The synchronous control device 9 can control the infrared thermometer 8 and the image acquisition unit 6 to work synchronously. The synchronization control device 9 may be a PLC (Programmable Logic Controller) or the like.
The image processing unit 10 can receive the temperature signal sent by the infrared thermometer 8 and the image of the measured object 1 collected by the image collecting unit 6. According to the collected image of the detected object 1, the image processing unit 10 may obtain the radiation light intensity value of each pixel point on the image of the detected object 1.
Fig. 2 shows a flowchart of a reflected light elimination method for temperature deformation simultaneous measurement according to an embodiment of the present disclosure. The method may be applied to the system shown in fig. 1, for example to the image processing unit 10. As shown in fig. 2, the method may include:
step 1, before heating the tested piece 1, obtaining the initial temperature T of the reference point of the tested piece 10And the initial light intensity (B) of the reference point of the piece 1 under testR0，BG0，BB0) Wherein B isR0Representing the initial intensity of the red channel, BG0Representing the initial intensity of the green channel, BB0Representing the initial intensity of the blue channel.
In one possible implementation, as shown in figure 1,before heating the object 1, a point on the object 1 may be selected as a reference point a of the object 1. The image processing unit 10 turns on the blue light source through the synchronization control device 9. The image processing unit 10 can control the infrared thermometer 8 to obtain the initial temperature T of the reference point a of the measured piece 1 through the synchronous control device 90The image of the measured object 1 is collected by the image collecting unit 6, and the initial light intensity (B) of the reference point a of the measured object 1 can be obtained according to the collected image of the measured object 1R0，BG0，BB0). For example, the image of the reference point a of the tested piece 1 is collected by the image collecting unit 6, the R, G, B brightness value of the reference point a can be obtained, and the initial light intensity (B) of the reference point a is obtained by analyzing according to the linear relationship between the light intensity of the pixel point and the brightness value thereof by using software such as MATLAB and the likeR0，BG0，BB0)。
The above manner of acquiring the initial temperature and the initial light intensity of the reference point of the measured object is only some examples of the disclosure, and the disclosure is not limited thereto, and the initial temperature value and the initial light intensity value of the reference point of the measured object may also be determined by other manners, for example, the light intensity of each pixel point may also be recorded in the process of scanning the measured object by an interference microscope and other devices, which are not listed.
And 2, heating the tested piece.
In one possible implementation, the test piece may be heated in a vacuum environment.
In one example, as shown in fig. 1, the experiment chamber of the arc wind tunnel is closed, the interior of the experiment chamber is vacuumized, and when the processed experiment chamber meets the vacuum condition, the image processing unit 10 turns on the arc through the synchronous control device 9, and pneumatically heats the tested piece 1.
Step 3, collecting the image of the tested piece, and determining the first radiant intensity (B) of each pixel point on the image according to the imageR1，BG1) Wherein B isR1、BG1Respectively representing the radiation intensity of a red light channel and the radiation intensity of a green light channel of each pixel point after the tested piece is heated;
each pixel point on the image may include a pixel point corresponding to the reference point a.
In a possible implementation manner, as shown in fig. 1, after the detected object 1 is heated, the image processing unit 10 can control the image acquisition unit 6 to acquire the image of the detected object 1 through the synchronous control device 9, can acquire the R, G, B brightness value of each pixel point on the image of the detected object 1 in real time, and analyzes and acquires the first radiant light intensity (B) of each pixel point according to the linear relationship between the radiant light intensity of the pixel point and the brightness value thereof by using software such as MATLAB and the likeR1，BG1) Obtaining the radiation intensity B of the red light channel of each pixel pointR1The radiant intensity B of the green channelG1。
Step 4, aiming at each pixel point on the image, according to the first radiation intensity (B) of the pixel pointR1，BG1) And the initial temperature T of the reference point0Initial light intensity (B)R0，BG0，BB0) Calculating the first temperature T1 of the pixel point and the radiation intensity B of the blue light channel by using the temperature measurement principle of the enhanced colorimetryB1Wherein B isB1The radiant intensity of the blue light channel of the pixel point is the radiant intensity after the tested piece is heated.
In one possible implementation, as shown in fig. 1, in step 3, a first radiant intensity (B) of each pixel point on the image of the detected piece 1 is obtainedR1，BG1) The blue light source 7 is used as an illumination light source of the arc wind tunnel, so that the red light channel and the green light channel of each pixel point on the image of the detected piece 1 have radiation light and reflection light caused by the blue light source 7, and therefore, the influence of the blue light source on the measured temperature needs to be effectively eliminated.
The initial light intensity (B) of the reference point a of the measured piece 1 obtained according to the step 1R0，BG0，BB0) Initial temperature T0, and first radiant intensity (B) obtained in step 3R1，BG1) According to the temperature measurement principle of the enhanced colorimetry, the first temperature T1 of each pixel point and the radiation intensity of the blue light channel of each pixel point after the tested piece 1 is heated can be calculated.
Specifically, step 4 may include:
step 41, aiming at each pixel point on the image, according to B of the pixel pointR1And BG1Initial light intensity of reference point BR0And BG0And T0And calculating the first temperature T1 of the pixel point by using the temperature measurement principle of the enhanced colorimetry.
According to the blackbody radiation law and the enhanced colorimetry temperature measurement principle, the relation between the radiation intensity and the temperature of the red light channel and the green light channel of each pixel point can be obtained as follows:
Figure BDA0001779869570000091
wherein, BRG0Is the ratio of the initial light intensity of the red light channel to the initial light intensity of the green light channel of the reference point a of the measured object 1, BRG1Is the ratio of the first radiant intensity of the red light channel and the green light channel of a certain pixel point on the image of the tested piece 1, C2Is the radiation constant, λRIs the wavelength, lambda, of red light radiated by the red light channel when the measured item 1 is heatedGIs the wavelength of the green light radiated by the green light channel when the object 1 is heated, T1 is the first temperature value after the object 1 is heated, T0Is the initial temperature of the reference point a of the measured piece 1.
For each pixel point, the first radiant intensity (B) of the pixel point is measuredR1，BG1) And the initial intensity of the reference point a (B)R0，BG0) Initial temperature T0Substituting into the above relation, the first temperature T1 of each pixel point can be calculated:
Figure BDA0001779869570000101
step 42, aiming at each pixel point on the image, according to T0、BR0、BB0And B of the pixel pointR1The first temperature T1, the radiation intensity B of the blue light channel of the pixel point is calculated by utilizing the temperature measurement principle of the enhanced colorimetryB1。
According to the blackbody radiation law and the enhanced colorimetry temperature measurement principle, the relation between the radiation intensity and the temperature of the red light channel and the blue light channel of each pixel point can be obtained as follows:
Figure BDA0001779869570000102
wherein, BRB0The ratio of the initial intensity of the red light channel to the initial intensity of the blue light channel at the reference point a of the measured object 1, BRB1Is the ratio of the first radiant intensity of the red light channel and the blue light channel of a certain pixel point on the image of the tested piece 1, lambdaBIs the wavelength of blue light emitted by the blue light source.
After the first temperature T1 of the pixel point is calculated in step S41, the first radiant light intensity B of the pixel point is measuredR1Temperature T1, and initial light intensity at reference point a (B)R0，BB0) Initial temperature T0Substituting into the above relation, the corrected radiation intensity B of the blue light channel of each pixel point can be calculatedB1：
Figure BDA0001779869570000103
For the reference point a, in order to distinguish from the initial light intensity, the radiation intensity of the blue light channel of the reference point calculated by the above process is recorded as BB0’。
Through the above process, the intensity of the radiation caused by the blue light source 7 can be calculated.
And 5, aiming at each pixel point on the image, according to the light intensity relation of the blue light channel and B of the pixel pointB1Determining the reflected light intensity B of the blue light channel of the pixel pointref。
The red light channel, the green light channel and the blue light channel of each pixel point can respectively receive the reflected light and the radiation light, so that the total light intensity of each light channel can be the sum of the reflected light intensity and the radiation light intensity of the light channel. Taking the blue light channel as an example, as shown in FIG. 1, the image is collected by the image collecting unit6, collecting the image of the tested piece 1 to obtain the total light intensity B of the blue light channel of each pixel point on the image of the tested piece 1tol. Calculating according to the step 4 to obtain the radiation intensity B of the blue light channel of each pixel pointB1. Therefore, the intensity of the reflected light of the blue light channel of each pixel point on the image of the tested piece 1 can be Bref＝Btol-BB1。
Step 6, aiming at each pixel point on the image, and according to B of the pixel pointrefCorrecting the B of the pixel pointR1、BG1Obtaining the corrected radiation intensity B of the red light channel and the green light channel of the pixel pointR1' and BG1’；
As described above, the blue light source 7 serves as an illumination light source of the arc wind tunnel, and each pixel point on the image of the detected piece 1 has the reflected light generated by the blue light source 7. According to the influence coefficient of the blue light source 7 on the radiation light of the red light channel and the green light channel of each pixel point and the reflected light intensity B of the blue light channel of the pixel pointrefThe radiation intensity of the red light channel and the green light channel of each pixel point can be corrected to obtain the corrected radiation intensity B of the red light channel of each pixel pointR1' and the modified radiant intensity B of the green channelG1', and the corrected radiation intensity of the reference point a of the measured object 1 is (B)R0’，BG0’)。
In one possible implementation, the method may further include: the influence coefficient of the blue light channel on the radiation light of the red light channel K1 and the influence coefficient of the radiation light of the green light channel K2 on the image are obtained.
Wherein K1 and K2 are related to the response of the image acquisition unit 6 to the blue light source 7 and the bandwidth of the filter 5, wherein the response curve of the image acquisition unit 6 to the blue light source 7 influences the response height of the blue light source to the red light and the green light. When the image acquisition unit 6 leaves the factory, the response curve of the blue light source 7 is determined, and then the response height of the blue light source to the red light and the green light is also determined to be unchanged. The bandwidth of the filter 5 can affect the band of light passing through the light source, and the wider the bandwidth, the wider the band of light passing through, the more unwanted light will pass through, and the measurement accuracy will be affected. The narrower the bandwidth of the filter 5, the narrower the light band passed through, and the higher the measurement accuracy. For example, in the case where the image pickup unit 6 has determined, the narrower the bandwidth of the filter 5, the smaller the values of K1 and K2, and the higher the measurement accuracy.
In one example, the image processing unit 10 may calculate K1 and K2 from the response parameters of the image pickup unit 6 to the blue light source 7 and the bandwidth of the filter 5.
In another example, the image processing unit 10 may also store the above calculated K1 and K2 locally, acquired each time needed.
In this embodiment, step 6 may include:
step 61, according to the reflected light intensity B of the blue light channel of the pixel pointrefAnd K1 correcting B of the pixel pointR1Obtaining the corrected radiation intensity B of the red light channel of the pixel pointR1’。
For example, the image processing unit 10 may calculate the corrected radiant intensity B of the red light channel of each pixel point according to the following formulaR1’：
B′R1＝BR1－K1﹡Bref。
Step 62, according to the blue light channel reflected light intensity B of the pixel pointrefAnd K2 correcting B of the pixel pointG1Obtaining the corrected radiation intensity B of the green light channel of the pixel pointG1’。
For example, the image processing unit 10 may calculate the corrected radiant intensity B of the green channel of each pixel point according to the following formulaG1’：
B′G1＝BG1－K2﹡Bref。
The above manners of correcting the radiation light of the red light channel and the green light channel of each pixel point are only some examples of the disclosure, and the disclosure is not limited thereto, and the radiation light of the red light channel and the green light channel of the pixel point may also be corrected by other manners, which are not listed.
Acquiring an image of a heated measured piece obtained by collecting the image, calculating the radiant light intensity of a red light channel and the radiant light intensity of a green light channel of each pixel point on the image, and calculating the first temperature of each pixel point and the radiant light intensity of the blue light channel by combining the initial light intensity and the initial temperature of a reference point and utilizing an enhanced colorimetry temperature measurement principle; then the reflected light intensity of the blue light channel can be obtained according to the light intensity relation of the blue light channel, so that the radiation light intensity of the pixel point can be corrected according to the calculated reflected light intensity of the blue light channel, and the influence of the reflected light on the measurement result can be effectively eliminated.
Step 7, aiming at each pixel point on the image, according to the corrected radiation intensity of the pixel point, the corrected radiation intensity of the reference point and T0Calculating a second temperature T2 of the pixel point by using an enhanced colorimetric temperature measurement principle;
as shown in FIG. 1, according to step 6, the corrected radiation intensity B of the red light channel of each pixel point on the image of the tested object 1 can be obtainedR1' corrected radiation intensity B of green light channelG1', the radiant intensity B of the blue light channelB1And the corrected radiation intensity (B) of the reference point a of the piece 1 to be measuredR0’，BG0') and the radiation intensity B of the blue light channelB0’。
Correcting radiation intensity of red light channel and green light channel of each pixel point on the image of the tested piece 1, correcting radiation intensity of red light channel and green light channel of reference point a, and initial temperature T of reference point a0Substituting into the relation among the red light channel, the green light channel and the temperature of each pixel:
Figure BDA0001779869570000131
the second temperature T2 of the pixel point is calculated,
Figure BDA0001779869570000132
the calculated first temperature may be further calibrated by calculating the second temperature further based on the corrected intensity of radiation.
And 8, if the difference value of the T2 and the T1 of each pixel point meets the convergence condition, determining the T2 of each pixel point as the temperature of the surface of the tested piece.
As shown in fig. 1, the first temperature T1 and the second temperature T2 of each pixel point on the image of the tested piece 1 are calculated according to the step 4 and the step 7.
The difference between the second temperature T2 and the first temperature T1 is obtained, and a temperature residual r of each pixel point on the image of the tested piece 1 can be obtained, that is, r is T2-T1. And when the temperature residual meets the convergence condition, determining the second temperature T2 of each pixel point as the temperature of the tested piece 1.
In one possible implementation manner, when the average value of the difference values of T2 and T1 of all the pixel points meets the convergence condition, determining T2 of each pixel point as the temperature of the surface of the measured piece;
in another possible implementation manner, when the maximum value of the absolute values of the difference values of T2 and T1 of all the pixel points meets the convergence condition, T2 of each pixel point is determined as the temperature of the surface of the measured object.
Wherein the convergence condition may be set to 10 degrees celsius. Taking this as an example, in one example, it is determined that the convergence condition is satisfied when the maximum value of the absolute values of the temperature residuals of each pixel point on the image of the measured piece 1 is less than or equal to 10 ℃. For example, when | rmaxAnd when the | is less than or equal to 10, determining the second temperature T2 of each pixel point as the temperature of the tested piece.
In another example, the convergence condition is determined to be satisfied when the average value of the temperature residuals of each pixel point on the image of the object 1 is less than or equal to 10 degrees celsius, for example, the temperature residuals of each pixel point are r respectively1、r2、r3……rnAverage value of temperature residual errors of pixel points
Figure BDA0001779869570000141
And when r is less than or equal to 10, determining the second temperature T2 of each pixel point as the temperature of the surface of the measured piece.
Of course, the convergence condition may also be set to be less than 5 degrees celsius, 30 degrees celsius, and the like, and the specific value of the convergence condition may be flexibly set according to experimental requirements, and is not limited herein.
And calculating to obtain a second temperature according to the corrected radiation intensity, and determining the second temperature of each pixel point as the temperature of the surface of the measured piece under the condition that the difference value between the second temperature and the first temperature of each pixel point meets the convergence condition.
According to the reflected light elimination method for temperature deformation synchronous measurement, the influence of reflected light in the temperature deformation synchronous measurement can be effectively eliminated, the result of the temperature deformation synchronous measurement is corrected, and the precision of the temperature deformation synchronous measurement is improved.
The image processing unit 10 can separate the blue light channel, obtain the radiation light and the reflected light of the blue light channel, and obtain the deformation data of the image of the tested piece 1 according to the reflected light.
Fig. 3 shows a flowchart of a reflected light elimination method for temperature deformation simultaneous measurement according to an embodiment of the present disclosure.
As shown in fig. 3, when the difference between the second temperature T2 and the first temperature T1 of each pixel point on the image of the test object satisfies the convergence condition, the second temperature T2 is determined as the temperature of the surface of the test object.
When the difference value between the second temperature T2 and the first temperature T1 of any pixel point on the image of the measured piece does not meet the convergence condition, the corrected radiant intensity (B) of the reference point of the measured pieceR0’，BG0') and the radiation intensity B of the blue light channelB0' determining the initial intensity of a reference point of the measured object, and correcting the intensity of the radiation (B) of each pixel point on the imageR1’，BG1') determining the first radiant light intensity of each pixel point, returning to the step 4, continuing to calculate the first temperature and the second temperature according to the steps 4-7, then judging whether the iterated first temperature and the iterated second temperature meet the convergence condition, and if not, repeating the above processes until the convergence condition is met.
As shown in FIG. 1, the difference between the second temperature T2 and the first temperature T1 of each pixel point on the image of the object 1When the convergence condition is not satisfied, the corrected radiation intensity B of the red light channel of each pixel point on the image of the detected piece 1 isR1' corrected radiation intensity B of green light channelG1' determining the corrected radiation intensity (B) of the reference point a of the measured object 1 as the first radiation intensity of the second iterationR0’，BG0') and the radiation intensity B of the blue light channelB0' determination as initial light intensity for the second iteration, the initial temperature of reference point a is still T0。
Fig. 4A is a graph showing the result of non-elimination of reflected light in an exemplary temperature deformation synchronization measurement.
As shown in fig. 4A, the x and y axes respectively represent the positions of the pixels. The right side is a temperature color bar corresponding to 700-. When the arc is heated, the temperature of the measured piece is gradually decreased from the center to the periphery, the temperature of the center is high, and the temperature of the edge is lowest. According to the temperature color bar, the higher the temperature is, the lighter the color is; the lower the temperature, the darker the color. The temperature color of the measured piece synchronously measured based on temperature deformation is gradually deepened from the center to the periphery, but the color of the peripheral edge of the measured piece is lighter than that of the central position. Therefore, the reflected light exists in the environment of synchronous measurement of temperature deformation, the temperature measurement result of the measured piece based on synchronous measurement of temperature deformation does not accord with the trend of true temperature value, and the measurement result is inaccurate.
Fig. 4B shows a schematic diagram of the result of eliminating reflected light in a temperature deformation simultaneous measurement according to an example of the present disclosure.
According to the measurement result of the reflected light elimination method for synchronous measurement of temperature deformation of the present disclosure, as can be seen from fig. 4B, the color of the temperature of the measured object based on the synchronous measurement of temperature deformation gradually deepens from the center to the periphery, that is, the temperature of the measured object gradually decreases from the center to the periphery. Therefore, the temperature measurement result of the measured piece based on the temperature deformation synchronous measurement reflected light elimination method is consistent with the trend of the true temperature value, and the accuracy of temperature measurement can be improved.
Fig. 5 shows a schematic diagram of results of simultaneous measurement of temperature deformation according to an example of the present disclosure.
As shown in fig. 5, the x-axis represents the positions of the pixels, and the y-axis represents the temperature value corresponding to each pixel. The square frame is a true temperature value of the measured piece, the true distribution trend of the true temperature value is approximately Gaussian distribution, wherein the true value of the measured piece can mean that the measured piece is heated under the condition of no external light, and the temperature value of the measured piece is measured by an infrared thermometer; the dotted line is the temperature value of the measured piece measured synchronously with the temperature deformation before the reflected light is eliminated; and the solid line is the temperature value of the measured piece synchronously measured by the temperature deformation after the reflected light is eliminated. Therefore, the temperature value obtained after the reflected light is eliminated is closer to the true temperature value than the temperature value of the measured piece measured synchronously by the temperature deformation with the reflected light. Therefore, the reflected light elimination method based on the temperature-deformation synchronous measurement of the measured piece can effectively eliminate the influence of reflected light in the temperature-deformation synchronous measurement, correct the result of the temperature-deformation synchronous measurement and improve the precision of the temperature-deformation synchronous measurement.
Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein were chosen in order to best explain the principles of the embodiments, the practical application, or technical improvements to the techniques in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims (8)

1. A reflected light elimination method for synchronous measurement of temperature deformation is characterized by comprising the following steps:
step 1, before heating a measured piece, acquiring an initial temperature T of a reference point of the measured piece0And an initial light intensity (B) of a reference point of the measured objectR0，BG0，BB0) Wherein B isR0Representing the initial intensity of the red channel, BG0Representing the initial intensity of the green channel, BB0Representing the initial light intensity of the blue channel;
step 2, heating the tested piece;
step 3, collecting the image of the tested piece, and determining the first radiant intensity (B) of each pixel point on the image according to the imageR1，BG1) Wherein B isR1、BG1Respectively representing the radiation intensity of a red light channel and the radiation intensity of a green light channel of each pixel point after the tested piece is heated;
step 4, aiming at each pixel point on the image, according to the first radiation intensity (B) of the pixel pointR1，BG1) And the initial temperature T of the reference point0Initial light intensity (B)R0，BG0，BB0) Calculating the first temperature T1 of the pixel point and the radiation intensity B of the blue light channel by using the temperature measurement principle of the enhanced colorimetryB1Wherein B isB1The radiation intensity of the blue light channel of the pixel point is the radiation intensity of the blue light channel after the tested piece is heated;
and 5, aiming at each pixel point on the image, according to the light intensity relation of the blue light channel and B of the pixel pointB1Determining the reflected light intensity B of the blue light channel of the pixel pointref；
Step 6, aiming at each pixel point on the image, and according to B of the pixel pointrefCorrecting the B of the pixel pointR1、BG1Obtaining the corrected radiation intensity B of the red light channel and the green light channel of the pixel pointR1' and BG1', and a corrected radiation intensity of the reference point (B)R0’，BG0') wherein, BR0' corrected radiation intensity of Red channel as reference point, BG0' a corrected radiant intensity of the green channel as a reference point;
step 7, aiming at each pixel point on the image, according to the corrected radiation intensity of the pixel point, the corrected radiation intensity of the reference point and T0Calculating a second temperature T2 of the pixel point by using an enhanced colorimetric temperature measurement principle;
and 8, if the difference value of the T2 and the T1 of each pixel point meets the convergence condition, determining the T2 of each pixel point as the temperature of the surface of the tested piece.
2. The reflected light removal method of claim 1, further comprising:
if the difference value between T2 and T1 of any pixel point does not meet the convergence condition, the corrected radiation intensity (B) of the reference point is usedR0’，BG0') and the radiation intensity B of the blue light channelB0' determination of initial intensity as reference point, correction of radiation intensity at each pixel point on the image (B)R1’，BG1') determines the first radiation intensity for each pixel point and returns to step 4.
3. The reflected light removal method according to claim 1, wherein step 4 includes:
aiming at each pixel point on the image, and according to B of the pixel pointR1And BG1Initial light intensity of reference point BR0And BG0And T0Calculating the first temperature T1 of the pixel point by using the temperature measurement principle of the enhanced colorimetry;
for each pixel point on the image, according to T0、BR0、BB0And B of the pixel pointR1The first temperature T1, the radiation intensity B of the blue light channel of the pixel point is calculated by utilizing the temperature measurement principle of the enhanced colorimetryB1。
4. The reflected light elimination method of claim 1, wherein in step 5, the relationship between the intensity of the blue light channel and the B value of the pixel point is determinedB1Determining the reflected light intensity B of the blue light channel of the pixel pointrefThe method comprises the following steps:
the total light intensity B of the blue light channel of the pixel pointtolWith the intensity of radiation BB1The difference of the two is used as the reflected light intensity B of the blue light channel of the pixel pointref。
5. The reflected light removal method of claim 1, further comprising:
the influence coefficient of the blue light channel on the radiation light of the red light channel K1 and the influence coefficient of the radiation light of the green light channel K2 on the image are obtained.
6. The reflected light removal method of claim 5, wherein B in step 6 is determined according to the pixel pointrefCorrecting the B of the pixel pointR1、BG1Obtaining the corrected radiation intensity B of the red light channel and the green light channel of the pixel pointR1' and BG1', includes:
according to the reflected light intensity B of the blue light channel of the pixel pointrefAnd K1 correcting B of the pixel pointR1Obtaining the corrected radiation intensity B of the red light channel of the pixel pointR1’；
According to the reflected light intensity B of the blue light channel of the pixel pointrefAnd K2 correcting B of the pixel pointG1Obtaining the corrected radiation intensity B of the green light channel of the pixel pointG1’。
7. A reflected light removal method according to claim 1, wherein step 8 includes:
and when the average value of the difference values of T2 and T1 of all the pixel points meets the convergence condition, determining the T2 of each pixel point as the temperature of the surface of the measured piece.
8. A reflected light removal method according to claim 1, wherein step 8 includes:
and when the maximum value of the absolute values of the difference values of the T2 and the T1 of all the pixel points meets the convergence condition, determining the T2 of each pixel point as the temperature of the surface of the measured piece.
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