Target object surface nondestructive measurement device and method

Abstract

The invention relates to a nondestructive measurement device and method for the surface of a target object. The device comprises a first light source, a lens, a linear dichroscope, a first image sensor and a second image sensor, the first light source emits first exciting light to a target object with a photoluminescence material, and the characteristic that the transmittance of the linear dichroscope is increased along with the increase of the wavelength is utilized; image processing is carried out on a first gray level image of target object detection light which is obtained by a first image sensor and penetrates through a linear dichroscope and a second gray level image of target object detection light which is obtained by a second image sensor and reflects the linear dichroscope, a mass center spectrum of each point of a target object is obtained, and then surface information of the target object is obtained. Through the non-contact detection device, physical damage to the electrode and the surface of the Micro LED chip caused by the probe can be avoided, so that wafer-level Micro LEDs can be detected so as to intercept dead pixels, and the yield of Micro LED display screens is improved.

Description

Technical Field

[0001] The present application relates to the field of Micro-LED display technology, and in particular to a device and method for non-destructive measurement of the surface of a target object. Background Art

[0002] With the continuous advancement of the manufacturing process of micro-gallium nitride (GaN) light emitting diodes (LEDs), GaN-based micro-light emitting diode (MicroLED) displays with the advantages of low power consumption, long life, small size and high reliability are expected to become a new generation of display technology and shine in the fields of near-eye display, large-size high-definition display devices, flexible screens, etc.

[0003] Among the many technical links of Micro LED display, wafer-level Micro LED chip detection is a key link to intercept bad pixels, improve the yield rate of display screens, and reduce the manufacturing cost of the whole machine. For large-scale (millions of orders of magnitude) and small-size (<50μm) wafer-level Micro LED chip arrays, the existing detection methods have the disadvantages of low detection efficiency and high cost. Therefore, improving detection efficiency, improving detection accuracy, and reducing detection costs are the development trends of wafer-level Micro LED detection technology. Summary of the invention

[0004] Based on this, it is necessary to provide a device and method for non-destructive measurement of the surface of a target object, which can improve detection efficiency and reduce detection costs, in order to address the above technical problems.

[0005] In a first aspect, the present application provides a device for non-destructive measurement of a target surface, comprising:

[0006] A first light source is used to emit a first excitation light to a target object; the target object includes a photoluminescent material;

[0007] A lens receives and adjusts the target detection light excited by the first excitation light;

[0008] a linear dichroic mirror that transmits at least a portion of the target detection light and reflects at least a portion of the target detection light; the linear dichroic mirror has a transmittance that increases with an increase in wavelength and a reflectance that decreases with a decrease in wavelength;

[0009] A first image sensor is arranged on a transmission light path of the linear dichroic mirror to obtain a first grayscale image of the target object detection light transmitted by the linear dichroic mirror; and

[0010] A second image sensor is arranged on a reflection light path of the linear dichroic mirror to obtain a second grayscale image of the target object detection light reflected by the linear dichroic mirror;

[0011] The centroid spectrum of each point of the target object is obtained by performing image processing on the first grayscale image and the second grayscale image; and the surface information of the target object is obtained based on the centroid spectrum of each point of the target object.

[0012] In one of the embodiments, the target surface non-destructive measurement device further includes: a light homogenizer, which is located at the emission end of the first light source and is used to receive the first excitation light emitted by the first light source and perform light homogenization on the light intensity of the first excitation light.

[0013] In one embodiment, the target object surface non-destructive measurement device further includes: a collimator, which is located at the output end of the homogenizer and is used to receive the homogenized first excitation light and adjust the emission angle of the first excitation light to be perpendicular to the surface of the target object.

[0014] In one embodiment, the target surface non-destructive measurement device further includes: a first filter, located in the optical path between the lens and the linear dichroic mirror, for filtering out the excitation light reflected by the target and transmitting the detection light through the target.

[0015] In one embodiment, the target surface non-destructive measurement device further includes:

[0016] An aperture, located at the emission end of the first light source, capable of blocking part of the light spot of the first excitation light to obtain the second excitation light;

[0017] The lens is opposite to the aperture, receives the second excitation light, and collimates the second excitation light, thereby converting the divergent light into parallel light; and the lens also receives the third excitation light and converges the third excitation light; wherein the third excitation light is obtained by reflecting the second excitation light from the target object;

[0018] A second filter, located in the optical path between the lens and the lens, is used to filter out the target object detection light and transmit the third excitation light;

[0019] The third image sensor receives the third excitation light to obtain a spot image of the third excitation light; obtains the defocus amount of the lens according to the spot image of the third excitation light, and adjusts the distance between the lens and the target object based on the defocus amount.

[0020] In one embodiment, the target surface non-destructive measurement device further includes:

[0021] A second light source is used to emit a fourth excitation light to the target object; the wavelength of the fourth excitation light is greater than the wavelength of the first excitation light;

[0022] An aperture, located at the emission end of the second light source, capable of blocking a portion of the light spot of the fourth excitation light to obtain a fifth excitation light;

[0023] The lens is opposite to the aperture, receives the fifth excitation light, and collimates the fifth excitation light, thereby converting the divergent light into parallel light; and the lens also receives the sixth excitation light and converges the sixth excitation light; wherein the sixth excitation light is obtained by reflecting the fifth excitation light from the target object;

[0024] A second filter, located on the optical path between the lens and the lens, is used to filter out the target object detection light and transmit the fifth excitation light and the sixth excitation light;

[0025] The third image sensor receives the sixth excitation light and obtains a spot image of the sixth excitation light; obtains the defocus amount of the lens according to the spot image of the sixth excitation light, and adjusts the distance between the lens and the target object based on the defocus amount.

[0026] In one embodiment, the first filter is also used to filter out the sixth excitation light.

[0027] In a second aspect, the present application also provides a method for non-destructive measurement of a target surface, comprising:

[0028] Controlling the first light source to emit a first excitation light; the first excitation light is incident on the target after being adjusted by the lens, and the target is excited to emit a target detection light; the target detection light is incident on the linear dichroic mirror after being adjusted by the lens again, at least part of the target detection light passes through the linear dichroic mirror, and at least part of the target detection light is reflected by the linear dichroic mirror; the transmittance of the linear dichroic mirror increases with the increase of wavelength, and the reflectance decreases with the decrease of wavelength;

[0029] receiving, by a first image sensor, at least a portion of the target object detection light transmitted through the linear dichroic mirror, to generate a first grayscale image;

[0030] receiving, by a second image sensor, at least a portion of the target object detection light reflected by the linear dichroic mirror to generate a second grayscale image;

[0031] Performing image processing on the first grayscale image and the second grayscale image to obtain a centroid spectrum of each point of the target object;

[0032] Based on the centroid spectrum of each point of the target object, the surface information of the target object is obtained.

[0033] In one embodiment, performing image processing on the first grayscale image and the second grayscale image to obtain a centroid spectrum of each point of the target object includes:

[0034] Obtain the transmittance curve of a linear dichroic mirror;

[0035] The transmittance curve is fitted to obtain the relationship between the wavelength of light passing through the linear dichroic mirror and the transmittance;

[0036] Get the gray value G of the first pixel at the first position in the first gray image T , obtain the gray value G of the second pixel at the second position in the second gray image R ; wherein the first position and the second position correspond to the same point of the target object;

[0037] Obtaining a total grayscale value of the same point of the target object based on the first pixel grayscale value and the second pixel grayscale value;

[0038] Based on the total gray value and the relationship between the wavelength of light and the transmittance, the centroid spectrum of the same point of the target object is obtained, and then the centroid spectrum of each point of the target object is obtained.

[0039] In one embodiment, before receiving at least a portion of the target object detection light transmitted through the linear dichroic mirror by a first image sensor to generate a first grayscale image, the target object surface non-destructive measurement method further includes:

[0040] After part of the light spot of the first excitation light is blocked by the aperture, the second excitation light is obtained; the second excitation light is received and collimated by the lens, thereby converting the divergent light into parallel light; the collimated second excitation light passes through the second filter and the lens and is incident on the target object, and is reflected by the target object to obtain the third excitation light; the third excitation light passes through the second filter to remove the target detection light and is incident on the lens;

[0041] receiving, by a third image sensor, the third excitation light converged by the lens, and generating a spot image of the third excitation light;

[0042] Obtaining the defocus amount of the lens according to the spot image of the third excitation light;

[0043] Adjust the distance between the lens and the target based on the defocus amount.

[0044] In one embodiment, before receiving at least a portion of the target object detection light transmitted through the linear dichroic mirror by a first image sensor to generate a first grayscale image, the target object surface non-destructive measurement method further includes:

[0045] The fourth excitation light emitted by the second light source is controlled; the wavelength of the fourth excitation light is greater than the wavelength of the first excitation light; a part of the light spot of the fourth excitation light is blocked by an aperture to obtain a fifth excitation light; the fifth excitation light is received and collimated by a lens, thereby converting the divergent light into parallel light; the collimated fifth excitation light passes through a second filter and a lens and is incident on a target object, and is reflected by the target object to obtain a sixth excitation light; the sixth excitation light passes through a second filter to remove the target object detection light and is incident on the lens;

[0046] receiving, by a third image sensor, the sixth excitation light converged by the lens, and generating a spot image of the sixth excitation light;

[0047] The defocus amount of the lens is obtained according to the spot image of the sixth excitation light, and the distance between the lens and the target object is adjusted based on the defocus amount.

[0048] The above-mentioned non-destructive measurement device and method for the surface of a target object emits excitation light to a target object having a photoluminescent material; and utilizes the characteristics of a linear dichroic mirror that a part of the incident light is reflected and a part is transmitted, and the linear dichroic mirror is arranged on the optical path of the target object detection light propagation; thereby, a first image sensor is arranged on the transmission optical path of the linear dichroic mirror, and a first grayscale image of the target object detection light transmitted by the linear dichroic mirror can be obtained; and a second image sensor is arranged on the reflection optical path of the linear dichroic mirror, and a second grayscale image of the target object detection light reflected by the linear dichroic mirror can be obtained; by performing image processing on the first grayscale image and the second grayscale image, a centroid spectrum of each point of the target object is obtained; and based on the centroid spectrum of each point of the target object, the surface information of the target object is obtained. Thus, on the basis of non-destructive testing of the target object, the surface information of the target object having a photoluminescent material is obtained, and further, based on the non-destructive testing, the surface defect information of the target object having a photoluminescent material can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are 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 creative work.

[0050] FIG1 is a schematic diagram of an optical path of a device for nondestructive measurement of a target surface in one embodiment;

[0051] FIG2 is a schematic diagram of an optical path of a target surface non-destructive measurement device in another embodiment;

[0052] FIG3 is a graph showing the transmittance of a linear dichroic mirror according to an embodiment;

[0053] FIG4 is a reflection and transmission image through a linear dichroic mirror in one embodiment;

[0054] FIG5 is a schematic diagram of a first light source homogenization shaping process in one embodiment;

[0055] FIG6 is a schematic diagram of an optical path of a target surface non-destructive measurement device according to another embodiment;

[0056] FIG7 is a schematic diagram of an optical path of a target surface nondestructive measurement device in yet another embodiment;

[0057] FIG8 is a schematic diagram of a flow chart of a method for non-destructive measurement of a target surface in one embodiment;

[0058] FIG9 is a schematic flow chart of a method for non-destructive measurement of a target surface in yet another embodiment;

[0059] FIG. 10 is a schematic flow chart of a method for non-destructive measurement of a target surface in another embodiment. DETAILED DESCRIPTION

[0060] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0061] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0062] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0063] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0064] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0065] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0066] At the current stage, the manufacturing process of Micro LED products mainly includes Micro LED epitaxy and Micro LED array preparation on sapphire substrates. The performance of Micro LED devices is also highly dependent on epitaxy technology, and the requirements for the consistency, uniformity and dislocation density of epitaxy wavelength are very high. In order to provide a non-destructive measurement solution for Micro LED, this application provides a non-destructive measurement device for the surface of a target object.

[0067] Please refer to FIG. 1 , which shows a schematic diagram of an optical path of a target surface non-destructive measurement device according to an embodiment of the present invention. The target surface non-destructive measurement device provided by the present invention according to an embodiment of the present invention includes:

[0068] A first light source 1 is used to emit a first excitation light to a target object 2; the target object 2 includes a photoluminescent material; a lens 3 receives and adjusts the target detection light excited by the first excitation light of the target object 2; a linear dichroic mirror 4 transmits at least a part of the target detection light and reflects at least a part of the target detection light; the transmittance of the linear dichroic mirror 4 increases with the increase of wavelength, and the reflectance decreases with the decrease of wavelength; a first image sensor 5 is arranged on the transmission light path of the linear dichroic mirror 4 to obtain a first grayscale image of the target detection light transmitted by the linear dichroic mirror 4; and a second image sensor 6 is arranged on the reflection light path of the linear dichroic mirror 4 to obtain a second grayscale image of the target detection light reflected by the linear dichroic mirror 4; wherein, by performing image processing on the first grayscale image and the second grayscale image, a centroid spectrum of each point of the target is obtained; and based on the centroid spectrum of each point of the target, surface information of the target is obtained. The first image sensor 5 or the second image sensor 6 may be a CCD (Charge-Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor) or a SCMOS (scientific CMOS).

[0069] Please refer to FIG. 2 at the same time, which shows a schematic diagram of the optical path of a target surface non-destructive measurement device in another embodiment of the present invention. A target surface non-destructive measurement device provided by another embodiment of the present invention includes:

[0070] The first light source 14' is used to emit a first excitation light to the target 2'; the target 2' includes a photoluminescent material; the lens 3' receives and adjusts the target detection light excited by the first excitation light of the target 2'; the linear dichroic mirror 4' transmits at least a part of the target detection light and reflects at least a part of the target detection light; the transmittance of the linear dichroic mirror 4' increases with the increase of wavelength, and the reflectivity decreases with the decrease of wavelength; the first image sensor 5' is arranged on the transmission light path of the linear dichroic mirror 4', and obtains a first grayscale image of the target detection light transmitted by the linear dichroic mirror 4'; and the second image sensor 6' is arranged on the reflection light path of the linear dichroic mirror 4', and obtains a second grayscale image of the target detection light reflected by the linear dichroic mirror 4'; wherein, by performing image processing on the first grayscale image and the second grayscale image, a centroid spectrum of each point of the target is obtained; and based on the centroid spectrum of each point of the target, surface information of the target is obtained. The first image sensor 5 ′ or the second image sensor 6 ′ may be a CCD (Charge-Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor) or a SCMOS (scientific CMOS).

[0071] Among them, photoluminescence (PL) refers to the process in which a substance re-radiates photons (or electromagnetic waves) after absorbing photons (or electromagnetic waves). From the perspective of quantum mechanics, this process can be described as the process in which a substance absorbs photons and transitions to an excited state of a higher energy level, then returns to a lower energy state and emits photons at the same time. It roughly goes through three main stages: absorption, energy transfer, and light emission. The absorption and emission of light both occur in transitions between energy levels and pass through excited states. The energy transfer is due to the movement of excited states. For semiconductor materials such as GaN, when it is irradiated with light whose photon energy is not less than its band gap, the valence band electrons will be excited to the conduction band and holes will be formed in the valence band. Unbalanced electrons and holes can cross the bandgap to undergo radiative recombination or radiative recombination through localized states in the bandgap, and their energy is released in the form of photons to form photoluminescence, thereby realizing the lighting of Micro LED lamp beads with GaN materials without power, for example, to achieve non-destructive testing.

[0072] It can be understood that for semiconductor materials with different doping ratios, the first light source 1 needs to be replaced with lasers with different wavelengths, which mainly depends on the band gap of the semiconductor material.

[0073] Exemplarily, light of a specific wavelength is emitted from the first light source 1, enters the main light path after turning the light path through the second beam splitter prism 16, and then is focused on the target object, such as the Micro LED sample, i.e., the surface of the target object, through the lens, so that the Micro LED lamp beads are excited and lit, wherein the lens can be an objective lens. The light emitted by the illuminated target object, i.e., the target detection light, is collected by the objective lens, and reaches the linear dichroic mirror 4 after passing through the second beam splitter prism 16 again. The linear dichroic mirror 4 is sensitive to the wavelength of light, and within the bandpass allowable range, its transmittance increases with the increase of wavelength, and its reflectivity decreases with the decrease of wavelength. After the light of a fixed wavelength enters the linear dichroic mirror 4, the light passing through the linear dichroic mirror 4 is collected by the first image sensor 5, and the light reflected by the linear dichroic mirror 4 is collected by the second image sensor 6. By processing the grayscale images, such as the first grayscale image and the second grayscale image, captured by the first image sensor 5 and the second image sensor 6, the centroid spectrum of the light emitted by the sample itself can be reversely deduced, and at the same time, the appearance defects of the sample lamp beads can be detected by processing the images.

[0074] As shown in FIG3 , it is a transmittance curve of the linear dichroic mirror 4. The horizontal axis represents the wavelength in nm (nanometers), and the vertical axis represents the transmittance of the linear dichroic mirror 4. The linear dichroic mirror 4 is sensitive to the wavelength of light. Within the passband allowable range (400-700 nm), its transmittance increases with the increase of wavelength, and its reflectivity decreases with the decrease of wavelength. The dotted line in FIG3 is the transmittance curve of the linear dichroic mirror 4, and the solid line is the transmittance curve obtained by fitting the transmittance curve. The R 2 The value reaches above 0.99. 2 The R-squared value is an indicator used to measure the goodness of fit of a model, especially in a linear regression model, where it indicates the degree of linear relationship between the independent variable and the dependent variable. 2 The value ranges from 0 to 1. The closer the value is to 1, the better the model fit and the better the linearity.

[0075] Therefore, under the condition that the linear curve of the linear dichroic prism is known, the transmission wavelength can be inverted by fitting its linear relationship. For example, the linear relationship of the linear dichroic prism is T = kλ+b, then λ = (Tb) / k. As shown in Figure 4, the reflection and transmission images collected through the linear dichroic mirror in the same field of view are taken. The gray value of the pixel at a certain position on the reflection image is G R , take the pixel gray value G at the same position on the transmission image T , we can calculate the sum of the grayscale at the same position on the two images as G, so we can calculate T = G T / G, then λ = ((G T / G)-b) / k.

[0076] In Figure 4, the bright area is the area illuminated by the light spot. The left picture is the image reflected by the linear dichroic mirror, and the right picture is the image transmitted by the linear dichroic mirror. The bright spot is the LED. The one clearly framed in the right picture is a typical LED lamp bead in the field of view. The specific judgment of the bad point can be determined by inverting the overall wavelength distribution of a single lamp bead. Uniformity is an important indicator for judging the quality of lamp beads, and the uniformity of wavelength is calculated based on the grayscale of the target shot. For example, in Figure 4, a lamp bead is a nearly rectangular white area. There will be some dark spots in a white area. This is the bad point area of ​​the lamp bead, which can be clearly observed. Of course, there are some that cannot be observed by the naked eye, and the difference with the surrounding pixel values ​​is not much, which requires more accurate calculation of pixel areas.

[0077] More importantly, the emission wavelength of Micro LED lamp beads is itself an important indicator to describe whether the LED is qualified and whether it can emit light of a specific wavelength without any discoloration or color cast.

[0078] In this embodiment, by emitting excitation light to a target having a photoluminescent material, and utilizing the characteristics that a linear dichroic mirror partially reflects and partially transmits incident light, and that the transmittance of the linear dichroic mirror increases with increasing wavelength and the reflectance decreases with decreasing wavelength, the linear dichroic mirror is arranged on the optical path of the target detection light propagation; thereby, a first image sensor is arranged on the transmission optical path of the linear dichroic mirror, and a first grayscale image of the target detection light transmitted by the linear dichroic mirror can be obtained; and a second image sensor is arranged on the reflection optical path of the linear dichroic mirror, and a second grayscale image of the target detection light reflected by the linear dichroic mirror can be obtained; by performing image processing on the first grayscale image and the second grayscale image, a centroid spectrum of each point of the target is obtained; and based on the centroid spectrum of each point of the target, surface information of the target is obtained. Thus, on the basis of performing nondestructive testing on the target, surface information of the target having a photoluminescent material is obtained, and further, based on the nondestructive testing, surface defect information of the target having a photoluminescent material can be obtained. The photoluminescence method of this embodiment can effectively capture the state of the lamp bead after it is lit. Of course, according to the captured image, the defects on the surface of the lamp bead, such as foreign matter, scratches, etc., can be detected first. These are similar to AOI (‌‌Automated Optical Inspection). Secondly, the bad pixel area may be stimulated to light up, but the luminous brightness is different from that of the normal area, or the bad pixel area will not be lit at all. Therefore, based on the wavelength distribution of the inverted lamp bead, the bad pixel at a certain point of the lamp bead can be detected.

[0079] In this embodiment, a contactless detection device composed of a first light source, a lens, a linear dichroic mirror, a first image sensor and a second image sensor can prevent the probe from causing physical damage to the electrode and surface of the Micro LED chip, thereby enabling wafer-level Micro LED detection to intercept bad pixels and improve the yield rate of the Micro LED display.

[0080] In one of the embodiments, the target object surface non-destructive measurement device further includes: a homogenizer 7, which is located at the emission end of the first light source 1 and is used to receive the first excitation light emitted by the first light source 1 and perform homogenization processing on the light intensity of the first excitation light.

[0081] Exemplarily, light of a specific wavelength is emitted from the first light source 1, homogenized by the light homogenizer 7, and then enters the main light path after turning the light path through the second beam splitter prism 16, and then focuses on the target object, such as the surface of the Micro LED sample, through the lens, so that the Micro LED lamp beads are excited and lit, wherein the lens can be an objective lens. The light emitted by the illuminated target, that is, the target detection light, is collected by the objective lens, and reaches the linear dichroic mirror 4 after passing through the second beam splitter prism 16 again. The linear dichroic mirror 4 is sensitive to the wavelength of light. Within the bandpass allowable range, its transmittance increases with the increase of wavelength, and its reflectivity decreases with the decrease of wavelength. After the light of a fixed wavelength enters the linear dichroic mirror 4, the light passing through the linear dichroic mirror 4 is collected by the first image sensor 5, and the light reflected by the linear dichroic mirror 4 is collected by the second image sensor 6. By processing the grayscale images captured by the first image sensor 5 and the second image sensor 6, such as the first grayscale image and the second grayscale image, the centroid spectrum of the light emitted by the sample itself can be reversely deduced, and at the same time, the appearance defects of the sample lamp beads can be detected by processing the images.

[0082] Among them, the photoluminescence of GaN semiconductor materials needs to satisfy the requirement that the photon energy is greater than its band gap, so as to excite the valence band electrons. Therefore, in this example, a semiconductor laser that meets the requirements is used as an excitation light source. The semiconductor laser has a narrow bandwidth, and its central wavelength drifts and energy is stable. It can make the Micro LED lamp beads stably light up during detection, but the light field distribution of the laser's output beam is a Gaussian distribution, that is, the light intensity of the beam gradually decreases from the center of the beam to the edge, as shown in the distribution form of the left figure of Figure 5. The central energy distribution is dense and the light intensity is the highest. The farther away from the center, the sparser the energy distribution and the weaker the light intensity. From the principle of photoluminescence, it can be seen that the photoluminescence intensity of the Micro LED lamp beads excited by light of different intensities is different. The linear dichroic mirror inversion wavelength used in this example is based on the lamp beads in the field of view of the image sensor being excited by a beam of the same light intensity. When the excitation beam is a Gaussian beam, it is necessary to perform beam analysis calibration on the Gaussian beam, which greatly increases the calculation process and cost, and introduces more errors. Therefore, the Gaussian beam is first shaped by the homogenizer 7 so that the beam emitted to the surface of the MicroLED lamp beads is evenly distributed.

[0083] Among the various beam shaping methods, the liquid core fiber homogenization method has low cost, wide transmission spectrum range, and better homogenization rate than traditional quartz fiber. Therefore, optionally, the energy distribution of the laser output light is converted from Gaussian distribution to uniform distribution spot by using liquid core homogenization fiber. As shown in Figure 5, after the Gaussian beam is homogenized, its light intensity distribution becomes uniform distribution, and circular and square spots can be selected according to actual conditions. The uniformly distributed spot can make the excited sample uniformly distributed in the field of view, avoiding the need to calibrate the incident light power again at different spot positions during measurement.

[0084] For semiconductor materials with different doping ratios, the first light source needs to be replaced with lasers of different wavelengths, which mainly depends on the band gap of the semiconductor material. Therefore, the input end of the homogenizer, such as the homogenizing optical fiber, has multiple interfaces that can transmit light of different wavelengths.

[0085] In this embodiment, in order to ensure that the intensity of the excitation light emitted by the light source can be evenly distributed when irradiating the target object, a homogenizer is used to perform light homogenization processing, so that the light intensity reaches a relatively uniform state on the surface of the target object, thereby avoiding differences in excitation effects caused by uneven light intensity and improving the accuracy and reliability of measurement.

[0086] In one embodiment, the target object surface non-destructive measurement device further includes: a collimator 8, which is located at the output end of the homogenizer 7 and is used to receive the homogenized first excitation light and adjust the emission angle of the first excitation light to be perpendicular to the surface of the target object.

[0087] Exemplarily, light of a specific wavelength is emitted from the first light source 1, homogenized by the light homogenizer 7, collimated by the collimator 8, and then enters the main light path after turning the light path through the second beam splitter prism 16, and then focuses on the target object, such as the surface of the Micro LED sample, through the lens, so that the Micro LED lamp beads are excited and lit, wherein the lens can be an objective lens. The light emitted by the illuminated target object, that is, the target detection light, is collected by the objective lens, and reaches the linear dichroic mirror 4 after passing through the second beam splitter prism 16 again. The linear dichroic mirror 4 is sensitive to the wavelength of light. Within the passband allowable range, its transmittance increases with the increase of wavelength, and its reflectivity decreases with the decrease of wavelength. After the light of a fixed wavelength enters the linear dichroic mirror 4, the light passing through the linear dichroic mirror 4 is collected by the first image sensor 5, and the light reflected by the linear dichroic mirror 4 is collected by the second image sensor 6. By processing the grayscale images captured by the first image sensor 5 and the second image sensor 6, such as the first grayscale image and the second grayscale image, the centroid spectrum of the light emitted by the sample itself can be reversely deduced. At the same time, by processing the images, the appearance defects of the sample lamp beads can be detected.

[0088] In this embodiment, the purpose of collimating the excitation light is to ensure that the light beam of the excitation light source can illuminate the surface of the target object perpendicularly. If there is an angle between the light beam and the surface of the material, the incident angle of the photon will no longer be uniform, which will cause the propagation path of the photon inside the material and the excitation effect to change. Through the collimation process, the light beam can be incident on the surface of the material at a perpendicular angle, thereby ensuring the consistency and repeatability of the excitation effect.

[0089] In one embodiment, the target surface non-destructive measurement device further includes: a first filter 9, located in the optical path between the lens 3 and the linear dichroic mirror 4, for filtering out the excitation light reflected by the target and transmitting the detection light through the target.

[0090] Exemplarily, light of a specific wavelength is emitted from the first light source 1, passes through the light homogenizer 7 and the collimator 8, turns the light path through the second beam splitter prism 16, and then enters the main light path, and then is focused on the target object, such as the surface of the Micro LED sample, through the lens, so that the Micro LED lamp beads are excited and lit, wherein the lens can be an objective lens. The light emitted by the illuminated target object, i.e., the target detection light, and the light reflected by the first light source 1 on the target object 2 are collected by the objective lens at the same time, and then pass through the second beam splitter prism 16 again to reach the first filter 9. The first filter 9 selects the wavelength of the light, allowing the light emitted by the sample itself, i.e., the light of the wavelength band of the target detection light, to pass through, and preventing the light of the wavelength band reflected back by the first light source 1 from passing through. The target detection light emitted by the target itself passes through the first filter 9 and reaches the linear dichroic mirror 4. The linear dichroic mirror 4 is sensitive to the wavelength of the light. Within the passband allowable range, its transmittance increases with the increase of the wavelength, and its reflectivity decreases with the decrease of the wavelength. After the light of fixed wavelength enters the linear dichroic mirror 4, the light transmitted through the linear dichroic mirror 4 is collected by the first image sensor 5, and the light reflected by the linear dichroic mirror 4 is collected by the second image sensor 6. By processing the grayscale images captured by the first image sensor 5 and the second image sensor 6, such as the first grayscale image and the second grayscale image, the centroid spectrum of the light emitted by the sample itself can be reversely deduced, and at the same time, the appearance defects of the sample lamp beads can be detected by processing the images.

[0091] In one embodiment, please refer to FIG. 6, which is a schematic diagram of the optical path of the target surface non-destructive measurement device in another embodiment. Another embodiment of the present invention provides a target surface non-destructive measurement device, which also includes: an aperture 10, located at the emission end of the first light source 1, capable of blocking part of the light spot of the first excitation light to obtain a second excitation light; a lens 11, opposite to the aperture 10, receiving the second excitation light, the lens 11 collimates the second excitation light, thereby converting the divergent light into parallel light; and the lens 11 also receives the third excitation light and converges the third excitation light; wherein the third excitation light is obtained by the target reflecting the second excitation light; a second filter 12, located on the optical path between the lens 3 and the lens 11, is used to filter out the target detection light and pass the third excitation light; a third image sensor 13, receives the third excitation light and obtains a light spot image of the third excitation light; the defocus amount of the lens is obtained according to the light spot image of the third excitation light, and the distance between the lens and the target is adjusted based on the defocus amount. The third image sensor 13 may be a CCD (Charge-Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), a SCMOS (scientific CMOS), or an AF CCD (Auto Focus Charge-Coupled Device).

[0092] Exemplarily, light of a specific wavelength is emitted from the first light source 1, and the first light source 1 emits a circular light spot. After passing through the homogenizer 7 and the collimator 8, the aperture 10' in the emission path will prevent half of the light spot of the first light source 1 from entering the light path. Therefore, the light of the first light source 1 passes through the first dichroic prism 15 in the form of a semicircle, is converged into parallel light by the lens 11, passes through the second filter 12, and then passes through the second dichroic prism 16 to turn the light path and enter the main light path, and then passes through the lens 3 to focus on the surface of the Micro LED sample, i.e., the target object 2, so that the Micro LED lamp beads are excited and lit, wherein the lens 3 can be an objective lens. The light emitted by the illuminated target, i.e., the target detection light, and the light reflected by the first light source 1 on the sample are collected by the objective lens at the same time, and reach the first filter 9 after passing through the second dichroic prism 16. The first filter 9 selects the wavelength of the light, allowing the light emitted by the sample itself, i.e., the target detection light, to pass through, and preventing the light of the band reflected back by the first light source 1 from passing through. The light emitted by the target 2 itself, i.e., the target detection light, passes through the first filter 9 and reaches the linear dichroic mirror 4. The linear dichroic mirror 4 is sensitive to the wavelength of light. Within the bandpass allowable range, its transmittance increases with the increase of wavelength, and its reflectivity decreases with the decrease of wavelength. After the light of a fixed wavelength enters the linear dichroic mirror 4, the light passing through the linear dichroic mirror 4 is collected by the first image sensor 5, and the light reflected by the linear dichroic mirror 4 is collected by the second image sensor 6. By processing the grayscale images captured by the first image sensor 5 and the second image sensor 6, such as the first grayscale image and the second grayscale image, the centroid spectrum of the light emitted by the sample itself can be reversely deduced, and at the same time, the appearance defects of the sample lamp beads can be detected by processing the images. Furthermore. The light of the first light source 1 reflected back will be passed by the second filter 12, while the possible interference light, such as the target detection light emitted by the sample itself, will be blocked by the second filter 12, and will be reflected to the third image sensor 13 after passing through the lens 11 and the first beam splitter prism 15 again. The third image sensor 13 collects the direction and radius of the semicircular light spot reflected by the first light source 1 to determine whether the sample is out of focus, thereby performing rapid automatic focusing.

[0093] For typical lens imaging, the focal length, object distance, and image distance of the lens satisfy the Gaussian formula (1):

[0094] 1 / f = 1 / u + 1 / v (1)

[0095] Where f represents the focal length of the optical system, u represents the object distance of the corresponding optical system, and v represents the image distance of the corresponding optical system.

[0096] According to the optical path formed by the lens 3 and the lens 11 in the device of FIG. 6 , the defocus amount z and the radius R of the semicircle detected by the third image sensor 13 can be established. x The mathematical relationship between them is shown in formula (2):

[0097] R x = (2f2 / f1)×z×tanθ (2)

[0098] Wherein f1 is the focal length of lens 3, f2 is the focal length of lens 11, z is the defocus amount, and tanθ is the constant NA (numerical aperture) of the lens.

[0099] Specifically, when the sample is detected, if a defocus amount z occurs, the third image sensor 13 can detect a semicircular light spot, where the defocus amount z and the radius R of the light spot are x In a linear relationship, when the system is defocused, z>0, then R x >0, producing an upper semicircle; when the focus is down and z<0, R x <0, the lower semicircle is generated. Thus, the radius and direction of the semicircle can be quickly calculated by the third image sensor 13 in cooperation with the measurement algorithm, thereby calculating the defocus amount z, and the motor is controlled to move quickly to the target position through the signal output, thereby achieving system focusing. Optionally, the system is fixed, the wafer moves, and real-time focusing and real-time acquisition are performed.

[0100] In this example, the first grayscale image and the second grayscale image acquired by the first image sensor 5 and the second image sensor 6 are collected by using a linear dichroic mirror to invert the wavelength, and the actual wavelength of the corresponding target detection light is deduced by calculating the grayscale of the same pixel position of the two images. Therefore, the consistency of the image size, position deviation accuracy and imaging clarity of the first image sensor 5 and the second image sensor 6 obtained is very high. Placing the first image sensor 5 and the second image sensor 6 in the same optical path can effectively avoid the errors caused by the image size and position deviation. Furthermore, in this example, an objective lens such as a microscope objective lens is used, which has a small depth of field, and a small height difference at different positions of the same target object will cause a difference in imaging clarity. Therefore, an autofocus component is added to eliminate the error of inconsistent imaging clarity caused by the height difference at different positions of the same product, thereby improving the detection accuracy.

[0101] In one embodiment, please refer to FIG. 7 , which is a schematic diagram of the optical path of a target surface non-destructive measurement device in yet another embodiment. Another embodiment of the present invention provides a non-destructive measurement device for the surface of an object, which also includes: a second light source 1', which is used to emit a fourth excitation light to the object; the wavelength of the fourth excitation light is greater than the wavelength of the first excitation light; an aperture 10', which is located at the emission end of the second light source 1' and can block part of the light spot of the fourth excitation light to obtain a fifth excitation light; a lens 11', which is opposite to the aperture 10' and receives the fifth excitation light, and the lens 11' collimates the fifth excitation light, thereby converting the divergent light into parallel light; and the lens 11' also receives a sixth excitation light and converges the sixth excitation light; wherein the sixth excitation light is obtained by reflecting the fifth excitation light from the object; a second filter 12', which is located on the optical path between the lens 3' and the lens 11', and is used to filter out the target detection light and transmit the fifth excitation light and the sixth excitation light; a third image sensor 13', which receives the sixth excitation light and obtains a light spot image of the sixth excitation light; the defocus amount of the lens is obtained according to the light spot image of the sixth excitation light, and the distance between the lens and the object is adjusted based on the defocus amount. The third image sensor 13 ′ may be a CCD (Charge-Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), a SCMOS (scientific CMOS), or an AF CCD (Auto Focus Charge-Coupled Device).

[0102] Exemplarily, light of a specific wavelength is emitted from the first light source 14', passes through the light homogenizer 7' and the collimator 8', enters the main light path after turning the light path through the second dichroic prism 16', passes through the third dichroic prism 17', and then is focused onto the Micro LED sample, i.e., the surface of the target object, through the lens 3', so that the Micro LED lamp beads are excited and lit, wherein the lens 3' may be an objective lens. The light emitted by the illuminated target object, i.e., the target detection light, and the light reflected from the first light source 14' onto the sample are collected by the objective lens at the same time, and reach the first filter 9' after passing through the third dichroic prism 17' and the second dichroic prism 16'. The first filter 9' selects the wavelength of light, allowing the light emitted by the sample itself, i.e., the target detection light, to pass through, and preventing the light of the wavelength band reflected back from the first light source 14' from passing through. The light emitted by the target 2' itself passes through the first filter 9' and reaches the linear dichroic mirror 4'. The linear dichroic mirror 4' is sensitive to the wavelength of light. Within the bandpass allowable range, its transmittance increases with the increase of wavelength, and its reflectivity decreases with the decrease of wavelength. After the light of a fixed wavelength enters the linear dichroic mirror 4', the light passing through the linear dichroic mirror 4' is collected by the first image sensor 5', and the light reflected by the linear dichroic mirror 4' is collected by the second image sensor 6'. By processing the grayscale images captured by the first image sensor 5' and the second image sensor 6', such as the first grayscale image and the second grayscale image, the centroid spectrum of the light emitted by the sample itself can be reversely deduced, and at the same time, by processing the image, the appearance defects of the sample lamp beads can be detected. The second light source 1' is a laser light source with a wavelength greater than that of the first light source 14', and its wavelength will be blocked by the first filter 9'. The second light source 1' emits a circular light spot, and the aperture 10' in the emission path will prevent half of the light spot of the second light source 1' from entering the light path. Therefore, the light from the second light source 1' passes through the first dichroic prism 15' in the form of a semicircle, is collimated into parallel light by the lens 11', and then passes through the second filter 12' to enter the third dichroic prism 17'. After being reflected by the third dichroic prism 17', it passes through the lens 3 and enters the sample surface. Similarly, the light from the second light source 1' reflected back will pass through the second filter 12', while possible interfering light such as the reflected light from the first light source 14' and the target detection light emitted by the sample itself will be blocked by the second filter 12'. The light from the second light source 1' reflected back is the sixth excitation light. The direction and radius of the semicircular light spot reflected back from the second light source 1' are collected by the third image sensor 13' to determine whether the sample is out of focus, so as to perform fast automatic focusing. The third image sensor 13' can be an AF CCD (AutoFocus Charge-Coupled Device, autofocus CCD).

[0103] For typical lens imaging, the focal length, object distance, and image distance of the lens satisfy the Gaussian formula (3):

[0104] 1 / f = 1 / u + 1 / v (3)

[0105] Where f represents the focal length of the optical system, u represents the object distance of the corresponding optical system, and v represents the image distance of the corresponding optical system.

[0106] According to the optical path formed by the lens 3' and the lens 11' in the device of FIG. 7, the defocus amount z and the radius R of the semicircle detected by the third image sensor 13' can be established. x The mathematical relationship between them is shown in formula (4):

[0107] R x =(2f2 / f1)×z×tanθ (4)

[0108] Wherein f1 is the focal length of the lens 3', f2 is the focal length of the lens 11', z is the defocus amount, and tanθ is the fixed value NA (numerical aperture) of the lens.

[0109] Specifically, when the sample is detected, if a defocus amount z occurs, the third image sensor 13' can detect a semicircular light spot, where the defocus amount z and the radius R of the light spot are x In a linear relationship, when the system is defocused, z>0, then R x >0, producing an upper semicircle; when the focus is down and z<0, R x <0, the lower semicircle is generated. Thus, the radius and direction of the semicircle can be quickly calculated by the third image sensor 13' in cooperation with the measurement algorithm, thereby calculating the defocus amount z, and the motor is controlled to move quickly to the target position through the signal output, thereby achieving system focusing. Optionally, the system is fixed, the wafer moves, and real-time focusing and real-time acquisition are performed.

[0110] In this example, the first grayscale image and the second grayscale image acquired by the first image sensor 5' and the second image sensor 6' are collected by using a linear dichroic mirror to invert the wavelength. The actual wavelength of the corresponding target detection light is deduced by calculating the grayscale of the same pixel position of the two images. Therefore, the image size, position deviation accuracy and imaging clarity consistency of the first image sensor 5' and the second image sensor 6' are very high. Placing the first image sensor 5' and the second image sensor 6' in the same optical path can effectively avoid the errors caused by image size and position deviation. Further, in this example, an objective lens such as a microscope objective lens is used, which has a small depth of field. The slight height difference at different positions of the same target object will cause a difference in imaging clarity. Therefore, an autofocus component is added to eliminate the error of inconsistent imaging clarity caused by the height difference at different positions of the same product, thereby improving the detection accuracy; and the autofocus system is integrated into the PL detection device, which can simultaneously complete the spectrum detection and AOI detection items, improve the detection rate, and reduce the cost.

[0111] Exemplarily, please refer to FIG. 7 again. In one embodiment, the first filter 9 is also used to filter out the sixth excitation light.

[0112] It can be understood that placing the target surface non-destructive measurement device into the automated testing equipment, combined with the robot and control system, can realize a fast and automatic testing process, and complete the sorting of OK (good) products and NG (Not Good) products, thereby improving the production yield of Micro LED.

[0113] Based on the same inventive concept, the present application also provides a method for non-destructive measurement of a target surface, as shown in FIG8 , including the following steps 802 to 810 .

[0114] Step 802, control the first light source to emit a first excitation light; the first excitation light is adjusted by the lens and incident on the target, exciting the target to emit a target detection light; the target detection light is adjusted by the lens again and incident on the linear dichroic mirror, at least part of the target detection light passes through the linear dichroic mirror, and at least part of the target detection light is reflected by the linear dichroic mirror; the transmittance of the linear dichroic mirror increases with the increase of wavelength, and the reflectance decreases with the decrease of wavelength.

[0115] Step 804 : receiving at least a portion of the target object detection light transmitted through the linear dichroic mirror via a first image sensor to generate a first grayscale image.

[0116] Step 806 : receiving at least a portion of the target object detection light reflected by the linear dichroic mirror via a second image sensor to generate a second grayscale image.

[0117] Step 808: Perform image processing on the first grayscale image and the second grayscale image to obtain a centroid spectrum of each point of the target object.

[0118] Step 810, obtaining surface information of the target object based on the centroid spectrum of each point of the target object.

[0119] For example, please refer to FIG. 1 again. The non-destructive measurement method of the target surface proposed in this embodiment includes: controlling the first light source 1 to emit a first excitation light. The first excitation light is adjusted by the lens 3 and incident on the target 2, exciting the target 2 to emit a target detection light. The target detection light is adjusted by the lens 3 again and incident on the linear dichroic mirror 4, at least part of the target detection light passes through the linear dichroic mirror 4, and at least part of the target detection light is reflected by the linear dichroic mirror 4; the transmittance of the linear dichroic mirror 4 increases with the increase of wavelength, and the reflectivity decreases with the decrease of wavelength. The first image sensor receives at least part of the target detection light that passes through the linear dichroic mirror 4 to generate a first grayscale image; the second image sensor receives at least part of the target detection light reflected by the linear dichroic mirror 4 to generate a second grayscale image. The first grayscale image and the second grayscale image are image processed to obtain the centroid spectrum of each point of the target; based on the centroid spectrum of each point of the target 2, the surface information of the target 2 is obtained.

[0120] For example, please refer to FIG. 2 again, which shows a method for nondestructive measurement of a target surface in another embodiment of the present invention, including: controlling a first light source 14' to emit a first excitation light. The first excitation light is adjusted by a lens 3' and incident on a target 2', exciting the target 2' to emit a target detection light. The target detection light is adjusted by the lens 3' again and incident on a linear dichroic mirror 4', at least part of the target detection light passes through the linear dichroic mirror 4', and at least part of the target detection light is reflected by the linear dichroic mirror 4'; the transmittance of the linear dichroic mirror 4' increases with the increase of the wavelength, and the reflectance decreases with the decrease of the wavelength. A first grayscale image is generated by receiving at least part of the target detection light that passes through the linear dichroic mirror 4' through a first image sensor; a second grayscale image is generated by receiving at least part of the target detection light that is reflected by the linear dichroic mirror through a second image sensor. The first grayscale image and the second grayscale image are image processed to obtain a centroid spectrum of each point of the target; and the surface information of the target is obtained based on the centroid spectrum of each point of the target.

[0121] In this embodiment, the target object detection light is separated by a linear dichroic mirror and then incident on the first image sensor and the second image sensor respectively, and the first grayscale image and the second grayscale image are respectively obtained. The centroid spectrum of each point of the target object is obtained by performing image processing on the first grayscale image and the second grayscale image; and the surface information of the target object is obtained based on the centroid spectrum of each point of the target object, which can prevent the probe from causing physical damage to the electrode and surface of the Micro LED chip, so that the Micro LED at the wafer level can be detected to intercept bad pixels and improve the yield rate of the Micro LED display.

[0122] In one embodiment, the centroid spectrum of each point of the target object is obtained by performing image processing on the first grayscale image and the second grayscale image, including: obtaining a transmittance curve of a linear dichroic mirror; fitting the transmittance curve to obtain a relationship between the wavelength and transmittance of a light wave passing through the linear dichroic mirror; obtaining a grayscale value G of a first pixel at a first position in the first grayscale image. T , obtain the gray value G of the second pixel at the second position in the second gray image R ; The first position and the second position correspond to the same point of the target object; the total grayscale value of the same point of the target object is obtained based on the first pixel grayscale value and the second pixel grayscale value; the centroid spectrum of the same point of the target object is obtained based on the total grayscale value and the relationship between the wavelength of the light wave and the transmittance, and then the centroid spectrum of each point of the target object is obtained.

[0123] Specifically, as shown in FIG3 , it is a transmittance curve of the linear dichroic mirror 4. The horizontal axis represents the wavelength in nm (nanometers), and the vertical axis represents the transmittance of the linear dichroic mirror 4. The linear dichroic mirror 4 is sensitive to the wavelength of light. Within the passband allowable range (400-700 nm), its transmittance increases with the increase of wavelength, and its reflectivity decreases with the decrease of wavelength. The dotted line in FIG3 is the transmittance curve of the linear dichroic mirror 4, and the solid line is the transmittance curve obtained by fitting the transmittance curve. The R 2 The value reaches above 0.99. 2 The R-squared value is an indicator used to measure the goodness of fit of a model, especially in a linear regression model, where it indicates the degree of linear relationship between the independent variable and the dependent variable. 2 The value ranges from 0 to 1. The closer the value is to 1, the better the model fit and the better the linearity.

[0124] Therefore, under the condition that the linear curve of the linear dichroic prism is known, the wavelength of the light wave passing through the linear dichroic mirror can be inverted by fitting its linear relationship. For example, the linear relationship of the linear dichroic prism is T = kλ+b, then λ =(Tb) / k, where λ is the wavelength of the light wave passing through the linear dichroic mirror, k and b are constants, and T represents the transmittance of the linear dichroic mirror. As shown in Figure 4, the reflection and transmission images of the linear dichroic mirror collected in the same field of view are taken. The grayscale value G of the reflection pixel at a certain position on the reflection image is taken. R , take the transmission pixel gray value G at the same position on the transmission image T , we can calculate the total grayscale of the same position on the two images, that is, the sum of the grayscales is G, so we can calculate T = G T / G, then λ = ((G T / G)-b) / k, that is, the wavelength λ of the light wave passing through the linear dichroic mirror and the sum of the grayscale G at the same position on the two images and the pixel grayscale value G at the same position on the transmission image T Furthermore, the wavelength λ of the light wave passing through the linear dichroic mirror is related to the grayscale value G of the transmitted pixel. T It is proportional to the ratio of the total grayscale G.

[0125] In one of the embodiments, before generating a first grayscale image by receiving at least part of the target detection light transmitted through the linear dichroic mirror through the first image sensor, the target surface non-destructive measurement method further includes: obtaining a second excitation light after a part of the light spot of the first excitation light is blocked by an aperture; the second excitation light is received and collimated by a lens, thereby converting the divergent light into parallel light; the collimated second excitation light passes through a second filter and a lens and is incident on the target, and is reflected by the target to obtain a third excitation light; the third excitation light passes through a second filter to remove the target detection light and is incident on the lens; the third excitation light is received by a third image sensor after being converged by the lens to generate a spot image of the third excitation light; the defocus amount of the lens is obtained according to the spot image of the third excitation light, and the distance between the lens and the target is adjusted based on the defocus amount.

[0126] For example, please refer to Figure 6 again. Figure 6 shows a method for non-destructive measurement of a target surface in another embodiment of the present invention, including: controlling the first light source 1 to emit a first excitation light. The first excitation light is adjusted by the lens 3 and incident on the target 2, exciting the target 2 to emit a target detection light. The target detection light is again adjusted by the lens 3 and incident on the linear dichroic mirror 4, at least part of the target detection light passes through the linear dichroic mirror 4, and at least part of the target detection light is reflected by the linear dichroic mirror 4; the transmittance of the linear dichroic mirror 4 increases with the increase of wavelength, and the reflectance decreases with the decrease of wavelength. Part of the spot of the first excitation light is also blocked by the aperture 10, so as to obtain the second excitation light; the second excitation light is received and collimated by the lens 11, so as to convert the divergent light into parallel light; the collimated second excitation light passes through the second filter 12 and the lens 3 and is incident on the target 2, and is reflected by the target 2 to obtain the third excitation light; the third excitation light passes through the second filter 12 to remove the target detection light and is incident on the lens 11; the third excitation light converged by the lens 11 is received by the third image sensor to generate a spot image of the third excitation light; the defocus amount of the lens is obtained according to the spot image of the third excitation light, and the distance between the lens and the target is adjusted based on the defocus amount. The first image sensor receives at least part of the target detection light passing through the linear dichroic mirror 4 to generate a first grayscale image; the second image sensor receives at least part of the target detection light reflected by the linear dichroic mirror 4 to generate a second grayscale image. The first grayscale image and the second grayscale image are processed to obtain a centroid spectrum of each point of the target object; and based on the centroid spectrum of each point of the target object 2, surface information of the target object 2 is obtained.

[0127] In this example, the first grayscale image and the second grayscale image acquired by the first image sensor 5 and the second image sensor 6 are collected by using a linear dichroic mirror to invert the wavelength, and the actual wavelength of the corresponding target detection light is deduced by calculating the grayscale of the same pixel position of the two images. Therefore, the consistency of the image size, position deviation accuracy and imaging clarity of the first image sensor 5 and the second image sensor 6 obtained is very high. Placing the first image sensor 5 and the second image sensor 6 in the same optical path can effectively avoid the errors caused by the image size and position deviation. Furthermore, in this example, an objective lens such as a microscope objective lens is used, which has a small depth of field, and a small height difference at different positions of the same target object will cause a difference in imaging clarity. Therefore, an autofocus component is added to eliminate the error of inconsistent imaging clarity caused by the height difference at different positions of the same product, thereby improving the detection accuracy.

[0128] In one of the embodiments, before generating a first grayscale image by receiving at least part of the target detection light transmitted through the linear dichroic mirror through the first image sensor, the target surface non-destructive measurement method also includes: controlling the second light source to emit a fourth excitation light; the wavelength of the fourth excitation light is greater than the wavelength of the first excitation light; a part of the light spot of the fourth excitation light is blocked by an aperture to obtain a fifth excitation light; the fifth excitation light is received and collimated by a lens, thereby converting the divergent light into parallel light; the collimated fifth excitation light passes through the second filter and the lens and is incident on the target, and is reflected by the target to obtain a sixth excitation light; the sixth excitation light passes through the second filter to remove the target detection light and is incident on the lens; the sixth excitation light is received by the third image sensor after being converged by the lens to generate a spot image of the sixth excitation light; the defocus amount of the lens is obtained according to the spot image of the sixth excitation light, and the distance between the lens and the target is adjusted based on the defocus amount.

[0129] For example, please refer to Figure 7 again. Figure 7 shows a method for non-destructive measurement of a target surface in another embodiment of the present invention, including: controlling the first light source 14' to emit a first excitation light. The first excitation light is adjusted by the lens 3' and incident on the target 2', exciting the target 2' to emit a target detection light. The target detection light is again adjusted by the lens 3' and incident on the linear dichroic mirror 4', at least part of the target detection light passes through the linear dichroic mirror 4', and at least part of the target detection light is reflected by the linear dichroic mirror 4'; the transmittance of the linear dichroic mirror 4' increases with the increase of wavelength, and the reflectance decreases with the decrease of wavelength. The second light source 1' is controlled to emit a fourth excitation light; the wavelength of the fourth excitation light is greater than the wavelength of the first excitation light; a part of the spot of the fourth excitation light is blocked by the aperture 10', and a fifth excitation light is obtained; the fifth excitation light is received and collimated by the lens 11', thereby converting the divergent light into a parallel light; the collimated fifth excitation light passes through the second filter 12' and the lens 3' and is incident on the target 2, and is reflected by the target 2 to obtain a sixth excitation light; the sixth excitation light passes through the second filter 12' to remove the target detection light and is incident on the lens 11'; the sixth excitation light converged by the lens 11' is received by the third image sensor to generate a spot image of the sixth excitation light; the defocus amount of the lens is obtained according to the spot image of the sixth excitation light, and the distance between the lens and the target is adjusted based on the defocus amount. The first image sensor receives at least part of the target detection light passing through the linear dichroic mirror 4' to generate a first grayscale image; the second image sensor receives at least part of the target detection light reflected by the linear dichroic mirror to generate a second grayscale image. The first grayscale image and the second grayscale image are processed to obtain a centroid spectrum of each point of the target object; and based on the centroid spectrum of each point of the target object 2, surface information of the target object 2 is obtained.

[0130] In this example, the first grayscale image and the second grayscale image acquired by the first image sensor 5' and the second image sensor 6' are collected by using a linear dichroic mirror to invert the wavelength. The actual wavelength of the corresponding target detection light is deduced by calculating the grayscale of the same pixel position of the two images. Therefore, the consistency of the image size, position deviation accuracy and imaging clarity acquired by the first image sensor 5' and the second image sensor 6' is very high. Placing the first image sensor 5' and the second image sensor 6' in the same optical path can effectively avoid the errors caused by image size and position deviation. Furthermore, in this example, an objective lens such as a microscope objective lens is used, which has a small depth of field, and a small height difference at different positions of the same target object will cause a difference in imaging clarity. Therefore, an autofocus component is added to eliminate the error of inconsistent imaging clarity caused by the height difference at different positions of the same product, thereby improving the detection accuracy.

[0131] In an exemplary embodiment, as shown in FIG. 9 , the present application further provides a method for non-destructive measurement of a target surface, including steps 902 to 922 below.

[0132] Step 902, control the first excitation light emitted by the first light source; after the first excitation light passes through the light homogenizer and the collimator, part of the light spot is blocked by the aperture to obtain the second excitation light; after the second excitation light passes through the first dichroic prism, it is received and collimated by the lens, thereby converting the divergent light into parallel light; the collimated second excitation light passes through the second filter, is deflected by the second dichroic prism, and is incident on the target object through the lens, and is reflected by the target object to obtain the third excitation light; and at the same time, the target object is excited to emit target detection light; after the third excitation light passes through the lens, it is deflected again by the second dichroic prism, filtered out the target detection light, and then is incident on the lens.

[0133] Step 904 : receiving the third excitation light converged by the lens through a third image sensor to generate a spot image of the third excitation light.

[0134] Step 906 , obtaining the defocus amount of the lens according to the spot image of the third excitation light.

[0135] Step 908: adjusting the distance between the lens and the target object based on the defocus amount.

[0136] In step 910, the target detection light is adjusted by the lens again and then incident on the first filter through the second beam splitter prism. After the third excitation light reflected by the target is filtered out by the first filter, the light is incident on the linear dichroic mirror. At least part of the target detection light passes through the linear dichroic mirror, and at least part of the target detection light is reflected by the linear dichroic mirror. The transmittance of the linear dichroic mirror increases with the increase of wavelength, and the reflectance decreases with the decrease of wavelength.

[0137] Step 912: Receive at least a portion of the target detection light transmitted through the linear dichroic mirror via a first image sensor to generate a first grayscale image.

[0138] Step 914: Receive at least a portion of the target object detection light reflected by the linear dichroic mirror via a second image sensor to generate a second grayscale image.

[0139] Step 916, obtaining a transmittance curve of the linear dichroic mirror; fitting the transmittance curve to obtain a relationship between the wavelength of light passing through the linear dichroic mirror and the transmittance.

[0140] Step 918: Obtain the grayscale value G of the first pixel at the first position in the first grayscale image. T , obtain the gray value G of the second pixel at the second position in the second gray image R ; wherein the first position and the second position correspond to the same point of the target object.

[0141] Step 920, based on the grayscale value of the first pixel and the grayscale value of the second pixel, obtain the total grayscale value of the same point of the target object; based on the total grayscale value and the relationship between the wavelength of the light wave and the transmittance, obtain the centroid spectrum of the same point of the target object, and then obtain the centroid spectrum of each point of the target object.

[0142] Step 922, based on the centroid spectrum of each point of the target object, obtain the surface information of the target object.

[0143] In an exemplary embodiment, as shown in FIG. 10 , the present application further provides a method for non-destructive measurement of a target surface, including the following steps 1002 to 1020 .

[0144] Step 1002, control the first light source to emit a first excitation light. After passing through the light homogenizer and the collimator, the first excitation light is deflected to the third dichroic prism via the second dichroic prism; the first excitation light passing through the third dichroic prism is adjusted by the lens and incident on the target, exciting the target to emit a target detection light; the first excitation light is also reflected by the target at the same time. The target detection light and the first excitation light reflected by the target are adjusted by the lens again and incident on the second dichroic prism via the third dichroic prism; the target detection light passes through the second dichroic prism and is incident on the first filter, and stray light is filtered out via the first filter; the stray light includes the first excitation light and the sixth excitation light reflected by the target. The target detection light is incident on the linear dichroic mirror, at least part of the target detection light passes through the linear dichroic mirror, and at least part of the target detection light is reflected by the linear dichroic mirror; the transmittance of the linear dichroic mirror increases with the increase of wavelength, and the reflectance decreases with the decrease of wavelength.

[0145] Step 1004, control the second light source to emit a fourth excitation light; the wavelength of the fourth excitation light is greater than the wavelength of the first excitation light; a part of the light spot of the fourth excitation light is blocked by the aperture to obtain a fifth excitation light. After the fifth excitation light passes through the first beam splitter prism, it is received and collimated by the lens, thereby converting the divergent light into parallel light; the collimated fifth excitation light passes through the second filter, is deflected by the third beam splitter prism, and is incident on the target object through the lens, and is reflected by the target object to obtain the sixth excitation light. After passing through the lens, the sixth excitation light is deflected again by the third beam splitter prism, filtered out by the second filter, and then incident on the lens to remove the target detection light.

[0146] Step 1006 , receiving the sixth excitation light converged by the lens through the third image sensor, and generating a spot image of the sixth excitation light.

[0147] Step 1008 , obtaining the defocus amount of the lens according to the spot image of the sixth excitation light, and adjusting the distance between the lens and the target object based on the defocus amount.

[0148] Step 1010 : receiving at least a portion of the target object detection light transmitted through the linear dichroic mirror via a first image sensor to generate a first grayscale image.

[0149] Step 1012: Receive at least a portion of the target object detection light reflected by the linear dichroic mirror via a second image sensor to generate a second grayscale image.

[0150] Step 1014, obtaining a transmittance curve of the linear dichroic mirror; fitting the transmittance curve to obtain a relationship between the wavelength of light passing through the linear dichroic mirror and the transmittance.

[0151] Step 1016, obtaining the grayscale value G of the first pixel at the first position in the first grayscale image T , obtain the gray value G of the second pixel at the second position in the second gray image R ; wherein the first position and the second position correspond to the same point of the target object.

[0152] Step 1018, based on the first pixel grayscale value and the second pixel grayscale value, obtain the total grayscale value of the same point of the target object; based on the total grayscale value and the relationship between the wavelength of the light wave and the transmittance, obtain the centroid spectrum of the same point of the target object, and then obtain the centroid spectrum of each point of the target object.

[0153] Step 1020, obtaining surface information of the target object based on the centroid spectrum of each point of the target object.

[0154] The above-mentioned non-destructive measurement method of the target surface is to emit excitation light to the target having photoluminescent material; and utilize the characteristics that the linear dichroic mirror partially reflects and partially transmits the incident light, and the transmittance of the linear dichroic mirror increases with the increase of wavelength, and the reflectance decreases with the decrease of wavelength, so as to arrange the linear dichroic mirror on the optical path of the target detection light propagation; thereby, the first image sensor is arranged on the transmission optical path of the linear dichroic mirror, and the first grayscale image of the target detection light transmitted by the linear dichroic mirror can be obtained; and the second image sensor is arranged on the reflection optical path of the linear dichroic mirror, and the second grayscale image of the target detection light reflected by the linear dichroic mirror can be obtained; by performing image processing on the first grayscale image and the second grayscale image, the centroid spectrum of each point of the target is obtained; and based on the centroid spectrum of each point of the target, the surface information of the target is obtained. Thus, on the basis of non-destructive testing of the target, the surface information of the target having photoluminescent material is obtained, and further, based on the non-destructive testing, the surface defect information of the target having photoluminescent material can be obtained. In addition, by integrating the autofocus system into the PL detection device, spectral detection and AOI detection items can be completed simultaneously, thereby improving the detection rate and reducing the cost.

[0155] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0156] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0157] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A non-destructive measuring device for a target surface, characterized in that: include: A first light source, used to emit a first excitation light to a target object; the target object includes a photoluminescent material; A lens, receiving and adjusting the target detection light excited by the first excitation light; a linear dichroic mirror, transmitting at least a portion of the target detection light and reflecting at least a portion of the target detection light; the transmittance of the linear dichroic mirror increases with increasing wavelength, and the reflectance decreases with decreasing wavelength; A first image sensor is arranged on a transmission light path of the linear dichroic mirror to obtain a first grayscale image of the target object detection light transmitted by the linear dichroic mirror; as well as A second image sensor is arranged on a reflection light path of the linear dichroic mirror to obtain a second grayscale image of the target detection light reflected by the linear dichroic mirror; Wherein, by performing image processing on the first grayscale image and the second grayscale image, a centroid spectrum of each point of the target object is obtained; And based on the centroid spectrum of each point of the target object, the surface information of the target object is obtained.

2. The target surface non-destructive measurement device according to claim 1, characterized in that: Also includes: A light homogenizer is located at the emission end of the first light source, and is used to receive the first excitation light emitted by the first light source and perform light homogenization processing on the light intensity of the first excitation light.

3. The target surface non-destructive measurement device according to claim 2, characterized in that: Also includes: A collimator, located at the output end of the light homogenizer, is used to receive the homogenized first excitation light and adjust the emission angle of the first excitation light to be perpendicular to the surface of the target object.

4. The target surface non-destructive measurement device according to claim 1, characterized in that: Also includes: The first filter is located on the optical path between the lens and the linear dichroic mirror, and is used to filter out the excitation light reflected by the target and to transmit the detection light through the target.

5. The target surface non-destructive measurement device according to any one of claims 1 to 4, characterized in that: Also includes: An aperture, located at the emission end of the first light source, capable of blocking a portion of the light spot of the first excitation light to obtain a second excitation light; a lens, opposite to the aperture, receiving the second excitation light, the lens collimating the second excitation light, thereby converting the divergent light into parallel light; and the lens also receiving the third excitation light, and converging the third excitation light; wherein the third excitation light is obtained by the target reflecting the second excitation light; A second filter, located on the optical path between the lens and the lens, for filtering out the target detection light and transmitting the third excitation light; The third image sensor receives the third excitation light and obtains a spot image of the third excitation light; obtains a defocus amount of the target surface non-destructive measurement device according to the spot image of the third excitation light, and adjusts the distance between the lens and the target based on the defocus amount.

6. The target surface non-destructive measurement device according to any one of claims 1 to 4, characterized in that: Also includes: a second light source, used to emit a fourth excitation light to the target object; the wavelength of the fourth excitation light is greater than the wavelength of the first excitation light; an aperture, located at the emission end of the second light source, capable of blocking a portion of the light spot of the fourth excitation light to obtain a fifth excitation light; a lens, opposite to the aperture, receiving the fifth excitation light, the lens collimating the fifth excitation light, thereby converting the divergent light into parallel light; and the lens also receiving the sixth excitation light, and converging the sixth excitation light; wherein the sixth excitation light is obtained by the target reflecting the fifth excitation light; a second filter, located on the optical path between the lens and the lens, for filtering out the target object detection light and transmitting the fifth excitation light and the sixth excitation light; The third image sensor receives the sixth excitation light and obtains a spot image of the sixth excitation light; obtains a defocus amount of the lens according to the spot image of the sixth excitation light, and adjusts the distance between the lens and the target object based on the defocus amount.

7. A method for non-destructive measurement of a target surface, characterized in that: The method comprises: Controlling a first light source to emit a first excitation light; the first excitation light is incident on a target after being adjusted by a lens, and excites the target to emit a target detection light; the target detection light is incident on a linear dichroic mirror after being adjusted by the lens, at least a portion of the target detection light passes through the linear dichroic mirror, and at least a portion of the target detection light is reflected by the linear dichroic mirror; the transmittance of the linear dichroic mirror increases with an increase in wavelength, and the reflectance decreases with a decrease in wavelength; receiving, by a first image sensor, at least a portion of the target object detection light transmitted through the linear dichroic mirror to generate a first grayscale image; receiving, by a second image sensor, at least a portion of the target object detection light reflected by the linear dichroic mirror to generate a second grayscale image; Performing image processing on the first grayscale image and the second grayscale image to obtain a centroid spectrum of each point of the target object; Based on the centroid spectrum of each point of the target object, the surface information of the target object is obtained.

8. The method according to claim 7, characterized in that The performing image processing on the first grayscale image and the second grayscale image to obtain a centroid spectrum of each point of the target object includes: Obtaining a transmittance curve of the linear dichroic mirror; Fitting the transmittance curve to obtain the relationship between the wavelength of light passing through the linear dichroic mirror and the transmittance; Obtain the grayscale value G of the first pixel at the first position in the first grayscale image T , obtain the grayscale value G of the second pixel at the second position in the second grayscale image R ; wherein the first position and the second position correspond to the same point of the target object; Obtaining a total grayscale value of the same point of the target object based on the first pixel grayscale value and the second pixel grayscale value; Based on the total gray value and the relationship between the wavelength of the light wave and the transmittance, the centroid spectrum of the same point of the target object is obtained, and then the centroid spectrum of each point of the target object is obtained.

9. The method according to claim 7 or 8, characterized in that: The method further comprises: receiving at least part of the target detection light transmitted through the linear dichroic mirror through the first image sensor and generating the first grayscale image, and obtaining a second excitation light after blocking part of the light spot of the first excitation light through an aperture; receiving and collimating the second excitation light through a lens, thereby converting the divergent light into parallel light; the collimated second excitation light passes through a second filter and the lens and is incident on the target, and is reflected by the target to obtain a third excitation light; the third excitation light passes through the second filter to remove the target detection light and is incident on the lens; receiving, by a third image sensor, the third excitation light converged by the lens, and generating a spot image of the third excitation light; Obtaining the defocus amount of the lens according to the spot image of the third excitation light; The distance between the lens and the target object is adjusted based on the defocus amount.

10. The method according to claim 7 or 8, characterized in that: Before the step of receiving at least a portion of the target object detection light transmitted through the linear dichroic mirror by the first image sensor to generate the first grayscale image, the step further includes: Control the second light source to emit a fourth excitation light; the wavelength of the fourth excitation light is greater than the wavelength of the first excitation light; a part of the light spot of the fourth excitation light is blocked by an aperture to obtain a fifth excitation light; the fifth excitation light is received and collimated by a lens, thereby converting the divergent light into parallel light; the collimated fifth excitation light passes through the second filter and the lens and is incident on the target object, and is reflected by the target object to obtain a sixth excitation light; the sixth excitation light passes through the second filter to remove the target detection light and is incident on the lens; receiving, by a third image sensor, the sixth excitation light converged by the lens, and generating a spot image of the sixth excitation light; The defocus amount of the lens is obtained according to the spot image of the sixth excitation light, and the distance between the lens and the target object is adjusted based on the defocus amount.

Images