Thermal reflection thermal imaging automatic refocusing method and device based on dual-area detection

Abstract

The present application is applicable to the field of temperature detection of microelectronic devices based on optical principles, and provides a method and device for automatic refocusing of thermal reflection thermal imaging based on dual-area detection, the method comprising: based on the reference image and the temperature change of the measured object, obtaining the first area and the second area of ​​the reference image, calculating the clarity of the two areas, and adjusting the three-axis nano-displacement stage; after each adjustment of the three-axis nano-displacement stage, obtaining the current measurement image, calculating the clarity of the two areas; the current measurement image still contains the above two areas; if the temperature of the measured object, the displacement of the three-axis nano-displacement stage, and the clarity of the second area meet the preset temperature threshold condition, the second preset displacement threshold condition, and the second preset clarity condition, and meet the first preset displacement threshold condition and the first preset clarity condition, determine the measurement result. The present application can improve the accuracy of the temperature measurement results and lay the foundation for realizing photothermal reflection imaging temperature measurement at high spatial resolution.

Description

Technical Field

[0001] The present application belongs to the field of temperature detection of microelectronic devices based on optical principles, and in particular to a method and device for automatic refocusing of thermal reflection thermal imaging based on dual-region detection. Background Art

[0002] When visible light shines on the surface of a material, the reflectivity of the material to visible light changes with the temperature of the material. The change in the reflectivity of the material to visible light is linearly related to the change in the temperature of the material surface:

[0003]

[0004] In the formula, △R is the change in reflectivity; R is the reflectivity value at the initial temperature; △T is the temperature change of the material being measured, in K; CTR is the thermal reflectivity calibration coefficient, in K-1.

[0005] According to the above principle, the change in the material surface temperature △T can be calculated by measuring the change in reflectivity △R. This test has a weak effective signal and strong noise, so methods such as multi-frame averaging must be used to enhance the signal-to-noise ratio.

[0006] In order to realize thermal reflection temperature measurement, in addition to measuring the reflectivity and reflectivity change, it is also necessary to know the CTR of the material being measured. The expression of CTR can be written as follows:

[0007]

[0008] The measurement of visible CTR needs to be achieved by measuring the rate of change of reflectivity under changing temperature. The actual thermal reflection temperature measurement device generally uses a CCD camera to measure the visible light signal reflected from the surface of the material, and cannot directly measure the reflectivity. After measuring the light intensity, the CCD camera converts the light intensity into an electrical signal, which is then digitized by the readout circuit and finally expressed in digital form. The value output by the CCD camera is generally called the camera reading (counts), represented by C, so the data finally processed by the computer is the reading of each pixel of the CCD camera. Therefore, formula (2) is rewritten as formula (3):

[0009]

[0010] Where C is the CCD reading at the initial temperature, and ΔC is the change in CCD reading when the temperature changes by ΔT. It must be noted that the CCD reading C is different at different temperatures when the wavelength of the light source is fixed, and the CCD reading is also different at different wavelengths when the temperature is fixed.

[0011] During the entire temperature measurement process, the measured object will expand and contract due to changes in ambient temperature, self-heating when powered on, etc. Since the optical thermal reflection imaging temperature measurement technology has a spatial resolution of microns or even sub-microns, thermal expansion and contraction will cause the measured object to change in three-dimensional direction, which will seriously affect the accuracy of the temperature measurement results. The change in position in the vertical direction is manifested as a decrease in image clarity and blur, that is, defocus, which will seriously affect the accuracy of the measurement results. Since temperature changes take some time to stabilize, the defocus phenomenon will develop continuously and gradually during the temperature change period during the thermal reflection thermal imaging temperature measurement process.

[0012] The existing photothermal reflection imaging temperature measurement technology achieves clear focus by repeatedly adjusting the position or angle of the relevant components of the imaging system under the condition that the position of the calibration plate remains fixed. This requires a specific graphic structure on the calibration plate. During the thermal reflection thermal imaging temperature measurement process, the vertical position of the measured object will change dynamically with the heating or cooling process, requiring a method that can continuously track and focus. The measured objects in thermal reflection temperature measurement are power devices and there are many types, which do not have the specific graphic structure of the calibration plate. This method cannot meet the needs of automatic refocusing of thermal reflection thermal imaging temperature measurement. Summary of the invention

[0013] In order to overcome the problems existing in the related art, the embodiments of the present application provide a method and device for automatic refocusing of thermal reflection thermal imaging based on dual-area detection, which can improve the accuracy of temperature measurement results and lay the foundation for realizing photothermal reflection imaging temperature measurement with high spatial resolution.

[0014] This application is implemented through the following technical solutions:

[0015] In a first aspect, an embodiment of the present application provides a method for automatic refocusing of thermal reflection thermal imaging based on dual-area detection, comprising: based on a reference image and a temperature change of a measured object, acquiring a first area and a second area of ​​the reference image, and calculating the clarity of the first area and the clarity of the second area; the reference image is a clearly focused image when the temperature remains unchanged;

[0016] Based on the temperature change of the measured object and the clarity of the first area and the clarity of the second area, the three-axis nano-displacement stage is adjusted; the temperature control device obtains the temperature change of the measured object; the measured object is placed on the temperature control device; the temperature control device is placed on the three-axis nano-displacement stage;

[0017] After adjusting the three-axis nano-displacement stage each time, a current measurement image is acquired, and the clarity of the first region and the clarity of the second region are calculated; the current measurement image still includes the first region and the second region;

[0018] Determine whether the temperature of the measured object, the displacement of the three-axis nano-displacement stage, and the clarity of the second region meet a preset temperature threshold condition, a second preset displacement threshold condition, and a second preset clarity condition;

[0019] If the temperature of the measured object, the displacement of the three-axis nano-translation stage, and the clarity of the second area meet the preset temperature threshold condition, the second preset displacement threshold condition, and the second preset clarity condition, then continue to adjust the three-axis nano-translation stage to determine whether the displacement of the three-axis nano-translation stage and the clarity of the first area meet the first preset displacement threshold condition and the first preset clarity condition;

[0020] If the displacement of the three-axis nano-translation stage and the first region clarity meet the first preset displacement threshold condition and the first preset clarity condition, a measurement result is determined.

[0021] In a possible implementation, the acquiring the first area and the second area, and calculating the definition of the first area and the definition of the second area include:

[0022] Acquiring the reference image;

[0023] Based on the reference image, a first area and a second area of ​​the reference image are acquired; the first area is a part of the reference image, the first area includes an image of a target area of ​​the test piece; the second area includes a pattern with obvious image contrast; the second area is larger than the first area;

[0024] Calculating the clarity of the first area based on the data of the first area;

[0025] The clarity of the second area is calculated based on the data of the second area.

[0026] In a possible implementation manner, the calculating the definition of the first area based on the data of the first area includes:

[0027] Acquire a pixel matrix within the first region, and perform horizontal and vertical differential operations on the pixel matrix within the first region;

[0028] Adding the difference operation results of the first area to obtain the data value of the clarity of the first area;

[0029] The calculating the definition of the second area based on the data of the second area includes:

[0030] Acquire a pixel matrix within the second area, and perform horizontal and vertical differential operations on the pixel matrix within the second area;

[0031] Adding the difference operation results of the second area to obtain a data value of the clarity of the second area;

[0032] The larger the data value of the clarity of the first area and the second area is, the higher the clarity is.

[0033] In a possible implementation, adjusting the three-axis nano-displacement stage based on the temperature change of the measured object and the clarity of the first region and the clarity of the second region includes:

[0034] Predicting the change direction of the vertical position of the measured object according to the temperature change of the measured object;

[0035] Based on the changing direction of the vertical position of the measured object, setting the stepping of the three-axis nano-displacement stage;

[0036] Based on the stepping of the three-axis nano-displacement stage, the measured object moves in the opposite direction to the changing direction of the vertical position.

[0037] In a possible implementation, the method based on the temperature change of the measured object and the clarity of the first area and the clarity of the second area further includes:

[0038] When the three-axis nano-translation stage moves for multiple times, the data value of the second area clarity is compared with the data value of the second area clarity last time, and if the data value of the second area clarity is greater than the data value of the second area clarity last time, the step of the three-axis nano-translation stage is the step of the three-axis nano-translation stage last time, and the moving direction is the same as the last moving direction;

[0039] If the data value of the second area clarity is smaller than the data value of the second area clarity last time, the stepping of the three-axis nano-displacement stage is recalculated, and the moving direction is opposite to the last moving direction.

[0040] In a possible implementation, the determining whether the temperature of the measured object, the displacement of the three-axis nano-displacement stage, and the clarity of the second region meet a preset temperature threshold condition, a second preset displacement threshold condition, and a second preset clarity condition includes:

[0041] If the temperature of the measured object, the displacement of the three-axis nano-displacement stage and the clarity simultaneously meet the preset temperature threshold condition, the second preset displacement threshold condition and the second preset clarity condition, then stop moving the three-axis nano-displacement stage;

[0042] If the temperature of the measured object, the displacement of the three-axis nano-displacement stage and the clarity do not simultaneously meet the preset temperature threshold condition, the second preset displacement threshold condition and the second preset clarity condition, continue to move the three-axis nano-displacement stage;

[0043] The preset temperature threshold condition is when the temperature fluctuation range of the measured object is less than the temperature threshold within a preset time period;

[0044] The second preset displacement threshold condition is that the step of the three-axis nano-displacement stage is smaller than the set displacement threshold;

[0045] The second preset definition condition is that the data value of the definition of the second area is greater than the data value of the definition of the second area last time.

[0046] In a possible implementation, if the temperature of the measured object, the displacement of the three-axis nano-displacement stage, and the clarity of the second region meet a preset temperature threshold condition, a second preset displacement threshold condition, and a second preset clarity condition, then continuing to adjust the three-axis nano-displacement stage includes:

[0047] The three-axis nano-displacement stage is adjusted based on the relative height between the first region and the second region; the relative height between the first region and the second region is obtained according to the structure of the measured object;

[0048] The nanostage is stepped in an initial step motion.

[0049] In a possible implementation, judging whether the displacement of the three-axis nano-displacement stage and the clarity of the first region meet a first preset displacement threshold condition and a first preset clarity condition, and determining a measurement result includes:

[0050] If the displacement of the three-axis nano-displacement stage and the clarity of the first region do not meet the first preset displacement threshold condition and the first preset clarity condition, continue to move the three-axis nano-displacement stage;

[0051] If the displacement of the three-axis nano-displacement stage and the clarity of the first region satisfy a first preset displacement threshold condition and a first preset clarity condition, determining a measurement result;

[0052] The first preset displacement threshold condition is that the step of the three-axis nano-displacement stage is smaller than the set displacement threshold;

[0053] The first preset definition condition is that the data value of the definition of the first area is greater than the data value of the definition of the first area last time.

[0054] In a possible implementation, if the displacement of the three-axis nano-displacement stage and the clarity of the first region do not satisfy a first preset displacement threshold condition and a first preset clarity condition, the three-axis nano-displacement stage continues to be moved;

[0055] The method of continuing to move the three-axis nano-translation stage comprises:

[0056] Based on the relative height of the first area and the second area, move the three-axis nano-translation stage;

[0057] When the three-axis nano-translation stage moves for multiple times, the data value of the first area definition is compared with the data value of the first area definition last time. If the data value of the first area definition is greater than the data value of the first area definition last time, the step of the three-axis nano-translation stage is the step of the three-axis nano-translation stage last time, and the moving direction is the same as the last moving direction;

[0058] If the data value of the first region definition is smaller than the data value of the first region definition last time, the stepping of the three-axis nano-displacement stage is recalculated, and the moving direction is opposite to the last moving direction.

[0059] In a second aspect, an embodiment of the present application provides a thermal reflection thermal imaging automatic refocusing device based on dual-area detection, comprising: a CCD camera, a fixing device, a light source, an objective lens, a temperature control device, a three-axis nano-displacement stage and an optical platform; the CCD camera is used to obtain a reference image;

[0060] The fixing device is arranged on the optical platform and is used to fix the CCD camera, the light source and the objective lens;

[0061] The temperature control device is arranged on the three-axis nano-displacement platform, and is used to place the measured object and obtain the temperature change of the measured object;

[0062] The three-axis nano-displacement stage is arranged on the optical platform and is used for adjusting the position movement of the measured object.

[0063] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0064] In the embodiment of the present application, the second area is first focused by setting a preset temperature threshold condition, a second preset displacement threshold condition and a second preset clarity condition, and then the first area is focused by setting the first preset displacement threshold condition and the first preset clarity condition, so that the image of the measured object is always kept clear, and image blur and data errors caused by defocus are eliminated. This is a key technology for realizing photothermal reflection temperature measurement, which can improve the accuracy of temperature measurement results and lay the foundation for realizing photothermal reflection imaging temperature measurement at high spatial resolution.

[0065] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0067] Figure 1 is a structural diagram of an automatic refocusing device provided in one embodiment of the present application;

[0068] Figure 2 is a flow chart of an automatic refocusing method provided by an embodiment of the present application;

[0069] Figure 3 is a reference image containing a rectangular area provided by an embodiment of the present application;

[0070] Figure 4 This is a diagram of image changes and image clarity changes during the automatic refocusing process provided by an embodiment of the present application. DETAILED DESCRIPTION

[0071] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0072] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0073] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0074] It should also be understood that the term "relative" used in the present specification and the appended claims refers to relative positions in mechanical movement.

[0075] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0076] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0077] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0078] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0079] Figure 1 It is a structural diagram of a heat reflection thermal imaging automatic refocusing device based on dual-region detection, and the heat reflection thermal imaging automatic refocusing method based on dual-region detection of the present invention is implemented based on the device.

[0080] In one embodiment, referring to Figure 1 A device for automatic refocusing of thermal reflection thermal imaging based on dual-area detection may include: a CCD camera 1, a fixing device 2, a light source 3, an objective lens 4, a temperature control device 5, a three-axis nano-displacement stage 6 and an optical platform 7. The CCD camera 1 is used to obtain all images; the fixing device 2 is arranged on the optical platform 7, and is used to fix the CCD camera 1, the light source 3 and the objective lens 4; the temperature control device 5 is arranged on the three-axis nano-displacement stage 6, and is used to place the DUT and obtain the temperature change of the DUT; the three-axis nano-displacement stage 6 is arranged on the optical platform 7, and is used to adjust the position movement of the DUT.

[0081] In one embodiment, see Figure 2, a device for automatic refocusing of thermal reflection thermal imaging based on dual-area detection, and a method for automatic refocusing of thermal reflection thermal imaging based on dual-area detection are described as follows:

[0082] Step 101: Acquire a first region and a second region of a reference image, and calculate the definition of the first region and the definition of the second region.

[0083] Wherein, based on the reference image and the temperature change of the measured object, the first area and the second area of ​​the reference image are obtained, and the clarity of the first area and the clarity of the second area are calculated; the reference image is a clearly focused image when the temperature remains unchanged.

[0084] See also Figure 3 , obtain the first area and the second area, and calculate the clarity of the first area and the second area, including: under a preset temperature condition, obtain a reference image A3; based on the reference image A3, obtain the first area A1 and the second area A2; the first area A1 is a part of the reference image A3, and the first area A1 includes a target area image A4 of the test piece; the second area A2 includes a graphic with obvious image contrast; the second area A2 is larger than the first area A1; based on the data of the first area A1, calculate the clarity of the first area A1; based on the data of the second area A2, calculate the clarity of the first area A2.

[0085] Exemplarily, the reference image refers only to the image in the initial state and when the temperature of the test piece does not change; the subsequent clarity data is also obtained by measuring the image of the test piece. Each time the nano-stage is adjusted, an image must be acquired first, and then the first and second areas mentioned above are acquired. The first and second areas are also images, and then the data on the image is acquired.

[0086] For example, for a device under test, the temperature changes in different areas are different. Some position changes are due to self-heating, and some temperature changes are due to heat conduction or other reasons. Therefore, the first area mentioned above must contain an image of the part to be measured, that is, the image of the target area of ​​the device under test.

[0087] Specifically, a first area A1 is selected on the reference image A3. The area should contain the target observation area, not any arbitrary area. The readings of each pixel in the rectangular area will form a matrix, with M1 rows corresponding to the image Y direction and N1 columns corresponding to the image X direction. At the same time, a larger second area A2 is selected on the image. The second area A2 should contain graphics with obvious image contrast, not any arbitrary area. The readings of each pixel in the second area A2 will form a matrix, with M2 rows corresponding to the image Y direction and N2 columns corresponding to the image X direction. Obtain the readings C[m][n] of each pixel in the rectangular area, where m is the number of rows in the rectangular area (0...M) and n is the number of columns in the rectangular area (0...N).

[0088] In the X direction, perform the difference operation:

[0089]

[0090] In the Y direction, perform the difference operation:

[0091]

[0092] Equation (4) and equation (5) are added together, and the sum is used as the definition data F.

[0093] Wherein, based on the data of the first area A1, the clarity of the first area A1 is calculated, including: obtaining the pixel matrix in the first area A1, performing differential operations on the pixel matrix in the first area A1 in the horizontal and vertical directions; adding the differential operation results of the first area A1 to obtain the data value of the clarity of the first area A1. Based on the data of the first area A2, the clarity of the first area A2 is calculated, including: obtaining the pixel matrix in the first area A2, performing differential operations on the pixel matrix in the first area A2 in the horizontal and vertical directions; adding the differential operation results of the first area A2 to obtain the data value of the clarity of the first area A2. Wherein, the larger the data value of the clarity of the first area A1 and the first area A2, the higher the clarity.

[0094] Step 102: adjusting the three-axis nano-translation stage based on the temperature change of the measured object and the clarity of the first area and the clarity of the second area.

[0095] The temperature control device obtains the temperature change of the measured object; the measured object is placed on the temperature control device; and the temperature control device is placed on the three-axis nano-displacement platform.

[0096] Among them, based on the temperature change and clarity of the measured object, the three-axis nano-displacement stage 6 is adjusted, including: predicting the change direction of the vertical position of the measured object according to the temperature change of the measured object; setting the stepping of the three-axis nano-displacement stage 6 each time based on the change direction of the vertical position of the measured object; and moving in the opposite direction of the change direction of the vertical position of the measured object based on each stepping of the three-axis nano-displacement stage 6.

[0097] Among them, adjusting the three-axis nano-translation stage 6 based on the temperature change and clarity of the measured part also includes: after the three-axis nano-translation stage 6 moves multiple times, comparing the data value of the clarity of the first area A2 with the data value of the clarity of the first area A2 last time, if the data value of the clarity of the first area A2 is greater than the data value of the clarity of the first area A2 last time, the step of the three-axis nano-translation stage 6 is the step of the three-axis nano-translation stage 6 last time, and the moving direction is the same as the last moving direction; if the data value of the clarity of the first area A2 is smaller than the data value of the clarity of the first area A2 last time, recalculating the step of the three-axis nano-translation stage, and the moving direction is opposite to the last moving direction.

[0098] Exemplarily, calculate the step of the three-axis nano-displacement stage 6 based on the frame rate of the camera 1, the resonance frequency of the three-axis nano-displacement stage 6, and the initial step.

[0099] Exemplarily, monitor the temperature T of the measured object with a thermocouple or other temperature measuring instrument. As the temperature of the measured object changes and defocus occurs to the measured object, the clarity data will necessarily become smaller. At this time, use the nano-displacement stage 6 based on piezoelectric ceramics to adjust the position of the Z-axis in real time. Predict the direction of the vertical position change of the measured object according to whether the temperature rises or falls. Generally, when the temperature rises, the vertical position of the measured object rises; when the temperature drops, the vertical position of the measured object drops. According to the predicted direction of the position change, set the nano-displacement stage 6 to move in the opposite direction of the vertical position change of the measured object with the initial step l0. Immediately collect an image after each movement is completed, and calculate its clarity data F x ; x is the number of displacements of the nano-displacement stage 6. It changes according to the depth of field of the objective lens 4 used, generally about 1 μm.

[0100] Exemplarily, after the nano-displacement stage 6 moves 2 times, compare the clarity data F 21 and F 22 , if F 21 <F 22 , then the nano-displacement stage 6 continues to move in the original direction with the step l0; if F 21 >F 22 , then the nano-displacement stage 6 moves in the opposite direction with the step l0.

[0101] Exemplarily, when the number of movements x is greater than or equal to 3, if F 2(x-1) <F 2x , then the nano-displacement stage 6 continues to move in the original direction with the step l0; if F 2(x-1) >F 2x , then the nano-displacement stage 6 moves in the opposite direction with the step kl0 (0 < k < 1), and the value of k is related to the frame rate of the CCD camera 1, the resonance frequency of the nano-displacement stage 6, etc.

[0102] Step 103, after each adjustment of the three-axis nano-displacement stage, obtain the current measurement image, and calculate the clarity of the first region and the clarity of the second region.

[0103] Wherein, the current measurement image still includes a first region and a second region.

[0104] Exemplarily, based on the data of the first area A1 of the current measurement image, the clarity of the first area A1 is calculated, including: obtaining the pixel matrix in the first area A1, performing differential operations on the pixel matrix in the first area A1 in the horizontal and vertical directions; adding the differential operation results of the first area A1 to obtain the data value of the clarity of the first area A1. Based on the data of the first area A2, the clarity of the first area A2 is calculated, including: obtaining the pixel matrix in the first area A2, performing differential operations on the pixel matrix in the first area A2 in the horizontal and vertical directions; adding the differential operation results of the first area A2 to obtain the data value of the clarity of the first area A2. The larger the data value of the clarity of the first area A1 and the first area A2, the higher the clarity.

[0105] Step 104 , determining whether the temperature of the test piece, the displacement of the three-axis nano-displacement stage, and the second region clarity meet a preset temperature threshold condition, a second preset displacement threshold condition, and a second preset clarity condition.

[0106] It is determined whether the temperature of the test piece, the displacement of the three-axis nano-displacement stage 6, and the clarity of the first area A2 meet the preset temperature threshold condition, the second preset displacement threshold condition, and the second preset clarity condition. If so, step 104 is executed, otherwise, step 102 is executed.

[0107] If the temperature of the measured object, the displacement and clarity of the three-axis nano-displacement stage 6 simultaneously meet the preset temperature threshold condition, the second preset displacement threshold condition and the second preset clarity condition, the movement of the three-axis nano-displacement stage 6 is stopped.

[0108] If the temperature of the measured object, the displacement and clarity of the three-axis nano-displacement stage 6 do not simultaneously meet the preset temperature threshold condition, the second preset displacement threshold condition and the second preset clarity condition, the three-axis nano-displacement stage 6 continues to be moved.

[0109] The preset temperature threshold condition is that the temperature fluctuation range of the measured object is less than the temperature threshold within the preset time period; the second preset displacement threshold condition is that the step of the three-axis nano-displacement stage 6 is less than the set displacement threshold; the second preset clarity condition is that the data value of the clarity of the first area A2 is greater than the data value of the clarity of the first area A2 last time.

[0110] For example, the temperature threshold T is set th (determined according to the required test accuracy, generally less than 0.5°C), when the temperature fluctuation of the measured object measured by the thermocouple is less than T th If kl0 is less than the set displacement threshold l th (generally less than 10% of the depth of field of the objective lens used) and F 2(x-1) <F 2xWhen the nanometer displacement stage 6 stops moving, the CCD camera is controlled to collect an image as an image for calculating the effective measurement result.

[0111] Step 105 , adjusting the three-axis nano-displacement stage, and determining whether the displacement of the three-axis nano-displacement stage and the clarity of the first region meet a first preset displacement threshold condition and a first preset clarity condition.

[0112] If the displacement of the three-axis nano-displacement stage and the clarity of the first region meet the first preset displacement threshold condition and the first preset clarity condition, step 105 is executed; otherwise, step 102 is executed.

[0113] Specifically, if the displacement of the three-axis nano-displacement stage 6 and the clarity of the first area A1 do not meet the first preset displacement threshold condition and the first preset clarity condition, the three-axis nano-displacement stage 6 continues to be moved.

[0114] If it is determined whether the displacement of the three-axis nano-displacement stage 6 and the clarity of the first area A1 meet the first preset displacement threshold condition and the first preset clarity condition, the measurement result is determined.

[0115] The first preset displacement threshold condition is that the step of the three-axis nano-displacement stage 6 is smaller than the set displacement threshold; the first preset clarity condition is that the clarity data value of the first area A1 is larger than the clarity data value of the first area A1 last time.

[0116] If the displacement of the three-axis nanometer displacement stage 6 and the clarity of the first area A1 do not meet the first preset displacement threshold condition and the first preset clarity condition, then continue to move the three-axis nanometer displacement stage 6, including:

[0117] Based on the relative height between the first area A1 and the first area A2, the three-axis nano-translation stage 6 is moved; after the three-axis nano-translation stage 6 has moved for multiple times, the data value of the clarity of the first area A1 is compared with the data value of the clarity of the first area A1 last time; if the data value of the clarity of the first area A1 is greater than the data value of the clarity of the first area A1 last time, the stepping of the three-axis nano-translation stage 6 is the same as the stepping of the three-axis nano-translation stage 6 last time, and the moving direction is the same as the last moving direction; if the data value of the clarity of the first area A1 is smaller than the data value of the clarity of the first area A1 last time, the stepping of the three-axis nano-translation stage 6 is recalculated, and the moving direction is opposite to the last moving direction.

[0118] Exemplarily, the specific direction of adjusting the nano displacement stage is: if the first area position is higher than the second area position, the initial moving direction of the nano displacement stage is downward movement; conversely, if the first area position is lower than the second area position, the initial moving direction of the nano displacement stage is upward movement.

[0119] Exemplarily, if the position of the first region A1 is higher than that of the first region A2 (the relative height of the two regions can be known according to the combined structure of the measured part), the nano-displacement stage 6 starts to move downward in the vertical direction with an initial step l0, and an image is collected immediately after each movement, and the clarity data F of the first region A2 is calculated 1x (where x is the displacement times of the nano-displacement stage).

[0120] Exemplarily, when the nano-displacement stage 6 moves 2 times, the clarity data F 11 and F 12 are compared. If F 11 <F 12 , the nano-displacement stage 6 continues to move in the original direction with a step l0; if F 11 >F 12 , the nano-displacement stage 6 moves in the opposite direction with a step l0.

[0121] Exemplarily, when the number of movements x is greater than or equal to 3, if F 1(x-1) <F 1x , the nano-displacement stage 66 continues to move in the original direction with a step l0; if F 1(x-1) >F 1x , the nano-displacement stage 6 moves in the opposite direction with a step kl0 (0 < k < 1), and the value of k is related to the frame rate of the CCD camera 1, the resonance frequency of the nano-displacement stage 6, etc.

[0122] Step 106, determine the measurement result.

[0123] Exemplarily, if kl0 is less than the set displacement threshold l th (generally less than 10% of the depth of field of the used objective lens) and F 1(x-1) <F 1x , the nano-displacement stage 6 stops moving, and the CCD camera 1 is controlled to collect an image as the measurement result.

[0124] The above measurement result is the refocused image, as well as data such as the pixel points and clarity optical signals of the refocused image.

[0125] Exemplarily, referring to Figure 4 , the clarity of the image refocused by the automatic refocusing method of thermal reflection thermal imaging based on dual-region detection of the present invention can be restored to the same position as the original clarity after defocusing.

[0126] The method of the present invention focuses on the second area first by setting a preset temperature threshold condition, a second preset displacement threshold condition and a second preset clarity condition to prevent the camera from being unable to track the object when the object is too small and changes too quickly with the temperature. Then, the first preset displacement threshold condition and the first preset clarity condition are set to focus on the first area, so that the image of the object under test always remains clear, image blur and data errors caused by defocusing are eliminated, and the accuracy of the temperature measurement results is improved.

[0127] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0128] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A thermal reflection thermal imaging automatic refocusing method based on dual-area detection, characterized in that: include: Based on the reference image and the temperature change of the measured object, a first area and a second area of ​​the reference image are acquired, and the clarity of the first area and the clarity of the second area are calculated; The reference image is a clearly focused image when the temperature remains unchanged; the first area includes an image of a target area of ​​the test piece; and the second area includes a graphic with a clear image contrast; The method comprises: adjusting the three-axis nano-displacement stage based on the temperature change of the measured object and the clarity of the first region and the clarity of the second region; a temperature control device acquires the temperature change of the measured object; the measured object is placed on the temperature control device; the temperature control device is placed on the three-axis nano-displacement stage; and adjusting the three-axis nano-displacement stage based on the temperature change of the measured object and the clarity of the first region and the clarity of the second region, comprising: Predicting the change direction of the vertical position of the measured object according to the temperature change of the measured object; Based on the change direction of the vertical position of the measured object, setting the initial step of the three-axis nano-displacement stage; Based on the initial step of the three-axis nano-displacement stage, move in a direction opposite to the change direction of the vertical position of the measured object; The method of adjusting the three-axis nanometer displacement stage based on the temperature change of the measured object and the clarity of the first area and the clarity of the second area also includes: When the three-axis nano-translation stage moves for multiple times, the data value of the second area clarity is compared with the data value of the second area clarity last time, and if the data value of the second area clarity is greater than the data value of the second area clarity last time, the step of the three-axis nano-translation stage is the step of the three-axis nano-translation stage last time, and the moving direction is the same as the last moving direction; If the data value of the second area definition is smaller than the data value of the second area definition last time, recalculating the step of the three-axis nanometer displacement stage based on the initial step, and the moving direction is opposite to the last moving direction; After adjusting the three-axis nano-displacement stage each time, a current measurement image is acquired, and the clarity of the first region and the clarity of the second region are calculated; the current measurement image still includes the first region and the second region; Determine whether the temperature of the measured object, the displacement of the three-axis nano-displacement stage, and the clarity of the second region meet a preset temperature threshold condition, a second preset displacement threshold condition, and a second preset clarity condition; If the temperature of the measured object, the displacement of the three-axis nano-translation stage, and the clarity of the second area meet the preset temperature threshold condition, the second preset displacement threshold condition, and the second preset clarity condition, then continue to adjust the three-axis nano-translation stage to determine whether the displacement of the three-axis nano-translation stage and the clarity of the first area meet the first preset displacement threshold condition and the first preset clarity condition; If the displacement of the three-axis nano-translation stage and the clarity of the first region meet the first preset displacement threshold condition and the first preset clarity condition, a measurement result is determined.

2. The automatic refocusing method for thermal reflection thermal imaging based on dual-area detection according to claim 1, characterized in that: The acquiring the first area and the second area of ​​the reference image, and calculating the definition of the first area and the definition of the second area, comprises: Acquiring the reference image; Based on the reference image, a first area and a second area of ​​the reference image are acquired; the first area is a part of the reference image, the first area includes an image of a target area of ​​the test piece; the second area includes a pattern with obvious image contrast; the second area is larger than the first area; Calculating the clarity of the first area based on the data of the first area; The clarity of the second area is calculated based on the data of the second area.

3. The automatic refocusing method for thermal reflection thermal imaging based on dual-area detection according to claim 2, characterized in that: The calculating the clarity of the first area based on the data of the first area includes: Acquire a pixel matrix within the first region, and perform horizontal and vertical differential operations on the pixel matrix within the first region; Adding the difference operation results of the first area to obtain the data value of the clarity of the first area; The calculating the definition of the second area based on the data of the second area includes: Acquire a pixel matrix within the second area, and perform horizontal and vertical differential operations on the pixel matrix within the second area; Adding the difference operation results of the second area to obtain a data value of the clarity of the second area; The larger the data value of the clarity of the first area and the second area is, the higher the clarity is.

4. The automatic refocusing method for thermal reflection thermal imaging based on dual-area detection according to claim 1, characterized in that: The determining whether the temperature of the measured object, the displacement of the three-axis nano-displacement stage and the second area clarity meet a preset temperature threshold condition, a second preset displacement threshold condition and a second preset clarity condition comprises: If the temperature of the measured object, the displacement of the three-axis nano-displacement stage and the clarity simultaneously meet the preset temperature threshold condition, the second preset displacement threshold condition and the second preset clarity condition, then stop moving the three-axis nano-displacement stage; If the temperature of the measured object, the displacement of the three-axis nano-displacement stage and the clarity do not simultaneously meet the preset temperature threshold condition, the second preset displacement threshold condition and the second preset clarity condition, continue to move the three-axis nano-displacement stage; The preset temperature threshold condition is when the temperature fluctuation range of the measured object is less than the temperature threshold within a preset time period; The second preset displacement threshold condition is that the step of the three-axis nano-displacement stage is smaller than the set displacement threshold; The second preset definition condition is that the data value of the definition of the second area is greater than the data value of the definition of the second area last time.

5. The automatic refocusing method for thermal reflection thermal imaging based on dual-area detection according to claim 1, characterized in that: If the temperature of the measured object, the displacement of the three-axis nano-displacement stage, and the clarity of the second region meet a preset temperature threshold condition, a second preset displacement threshold condition, and a second preset clarity condition, then continue to adjust the three-axis nano-displacement stage, including: The three-axis nano-displacement stage is adjusted based on the relative height between the first region and the second region; the relative height between the first region and the second region is obtained according to the structure of the measured object; The nanostage is stepped in an initial step motion.

6. The automatic refocusing method for heat reflection thermal imaging based on dual-area detection according to claim 1, characterized in that: Determining whether the displacement of the three-axis nano-displacement stage and the clarity of the first region meet a first preset displacement threshold condition and a first preset clarity condition, and determining a measurement result, includes: If the displacement of the three-axis nano-displacement stage and the clarity of the first region do not meet the first preset displacement threshold condition and the first preset clarity condition, continue to move the three-axis nano-displacement stage; If the displacement of the three-axis nano-displacement stage and the clarity of the first region satisfy a first preset displacement threshold condition and a first preset clarity condition, determining a measurement result; The first preset displacement threshold condition is that the step of the three-axis nano-displacement stage is less than the set displacement threshold; The first preset definition condition is that the data value of the definition of the first area is greater than the data value of the definition of the first area last time.

7. The automatic refocusing method for heat reflection thermal imaging based on dual-area detection according to claim 6, characterized in that: If the displacement of the three-axis nano-displacement stage and the clarity of the first region do not meet the first preset displacement threshold condition and the first preset clarity condition, continue to move the three-axis nano-displacement stage; The method of continuing to move the three-axis nano-translation stage comprises: Based on the relative height of the first area and the second area, move the three-axis nano-translation stage; When the three-axis nano-translation stage moves for multiple times, the data value of the first area definition is compared with the data value of the first area definition last time. If the data value of the first area definition is greater than the data value of the first area definition last time, the step of the three-axis nano-translation stage is the step of the three-axis nano-translation stage last time, and the moving direction is the same as the last moving direction; If the data value of the first area definition is smaller than the data value of the first area definition last time, the step of the three-axis nano-displacement stage is recalculated based on the initial step, and the moving direction is opposite to the last moving direction.

8. A thermal reflection thermal imaging automatic refocusing device based on dual-area detection, characterized in that: Used to implement the automatic refocusing method of thermal reflection thermal imaging based on dual-area detection as described in any one of claims 1 to 7, comprising: a CCD camera, a fixing device, a light source, an objective lens, a temperature control device, a three-axis nano-displacement stage and an optical platform; The CCD camera is used to acquire all images; The fixing device is arranged on the optical platform and is used to fix the CCD camera, the light source and the objective lens; The temperature control device is arranged on the three-axis nano-displacement platform, and is used to place the measured object and obtain the temperature change of the measured object; The three-axis nano-displacement stage is arranged on the optical platform and is used for adjusting the position movement of the measured object.

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