Optical measuring devices and systems

Abstract

This disclosure discloses an optical measurement apparatus and system. The apparatus includes a beam splitter module comprising at least one optical element coated with an optical thin film, the transmittance and / or reflectance of which monotonically vary with wavelength within the measurement wavelength range; and at least two image sensors, each disposed downstream of the optical path of the beam splitter module. At least one of the image sensors is configured to receive a light beam output via the optical thin film and generate image information, wherein the image information is used to obtain a two-dimensional wavelength distribution map of the sample to be tested. The embodiments provided in this disclosure effectively shorten wavelength measurement time through the innovative combination of an optical thin film with monotonically varying transmittance and / or reflectance within the measurement wavelength range and a dual-path synchronous imaging architecture.

Description

Technical Field

[0001] This disclosure generally relates to the field of optical measurement technology, and more specifically, to an optical measurement device and system. Background Technology

[0002] In the field of modern optical measurement, measuring the wavelength distribution of luminescent samples is of great significance. Traditional measurement methods often suffer from problems such as slow speed, making it difficult to meet the current demand for high-efficiency detection.

[0003] In existing technologies, single-point measurement is typically used, employing equipment such as spectrometers to measure the wavelength of the luminescent sample point by point. This method is not only slow, but also struggles to guarantee uniformity and accuracy when measuring large-area luminescent samples. Furthermore, traditional methods are easily affected by ambient light during measurement, further compromising the reliability of the results.

[0004] In view of this, this application provides a system and method for rapidly measuring the two-dimensional wavelength distribution of luminescent samples, which can realize rapid measurement of the wavelength of luminescent samples and effectively improve measurement efficiency. Summary of the Invention

[0005] In order to at least address one or more of the technical problems mentioned above, this disclosure proposes an optical measurement device and system scheme in several aspects.

[0006] In a first aspect, this disclosure provides an optical measurement apparatus comprising: a beam splitter module including at least one optical element coated with an optical thin film, the transmittance and / or reflectance of the optical thin film varying monotonically with wavelength within a measurement band; and at least two image sensors disposed downstream of the optical path of the beam splitter module, at least one of the at least two image sensors being configured to receive a light beam output via the optical thin film and generate image information, wherein the image information is used to calculate and generate a two-dimensional wavelength distribution map of the sample to be tested.

[0007] In a second aspect, this disclosure provides an optical measurement system, comprising: an optical measurement device as described in the first aspect and a processor communicatively connected to an image sensor, the processor being configured to: calculate and generate a two-dimensional wavelength distribution map of a sample to be tested based on image information from the image sensor.

[0008] In a third aspect, this disclosure provides an optical measurement system, such as the optical measurement apparatus described in the first aspect and a bright-field / dark-field detection optical element group disposed within a beam-splitting module. The bright-field / dark-field detection optical element group includes a first filter, a second filter, a first optical path mode switching mechanism, and a second optical path mode switching mechanism. When the optical element is a filter element and the beam-splitting module further includes at least one compensation element, the first optical path mode switching mechanism and the second optical path mode switching mechanism are configured to synchronously respond to a control signal and perform the following switching operations: when the first optical path mode switching mechanism switches the filter element into the optical path and the second optical path mode switching mechanism switches the compensation element into the optical path, the optical measurement system is configured to measure the two-dimensional distribution of the emission wavelength of the sample to be detected; or, when the first optical path mode switching mechanism switches the first filter into the optical path and the second optical path mode switching mechanism switches the second filter into the optical path... The optical measurement system is configured to perform automatic bright-field / dark-field optical detection on the sample to be tested; or, when the optical elements include a first filter element and a second filter element respectively disposed on the optical paths of two beams, the first filter element being coated with a first optical thin film and the second filter element being coated with a second optical thin film, the first optical path mode switching mechanism and the second optical path mode switching mechanism are configured to synchronously respond to the control signal and perform the following switching operation: when the first optical path mode switching mechanism switches the first filter element into the optical path and the second optical path mode switching mechanism switches the second filter element into the optical path, the optical measurement system is configured to measure the two-dimensional distribution of the emission wavelength of the sample to be tested; or, when the first optical path mode switching mechanism switches the first filter element into the optical path and the second optical path mode switching mechanism switches the second filter element into the optical path, the optical measurement system is configured to perform automatic bright-field / dark-field optical detection on the sample to be tested.

[0009] The optical measurement apparatus and system provided in this disclosure include a beam splitting module comprising at least one optical element coated with an optical thin film, the transmittance and / or reflectance of which monotonically vary with wavelength within the measurement band; at least two image sensors, each disposed downstream of the optical path of the beam splitting module, at least one of which is configured to receive a light beam output via the optical thin film and generate image information, wherein the image information is used to calculate and generate a two-dimensional wavelength distribution map of the sample to be tested. Through the innovative combination of an optical thin film with monotonically varying transmittance and / or reflectance within the measurement band and a dual-path synchronous imaging architecture, it effectively shortens the wavelength measurement time compared to traditional spectral scanning methods.

[0010] Furthermore, the optical measurement system with dual working modes can meet different detection needs and adapt to a variety of detection tasks. Attached Figure Description

[0011] The above and other objects, features, and advantages of exemplary embodiments of this disclosure will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this disclosure are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0012] Figure 1 A schematic diagram of the structure of an optical measuring device 100 according to some embodiments of this disclosure is shown;

[0013] Figure 2 A schematic diagram of the structure of an optical measuring device 200 according to some embodiments of this disclosure is shown;

[0014] Figure 3 A schematic diagram of a portion of the optical path in some embodiments of this disclosure is shown;

[0015] Figure 4(a) shows the relationship between transmittance and wavelength in some embodiments of this disclosure;

[0016] Figure 4(b) shows a schematic diagram of the structure of a filter element according to some embodiments of this disclosure;

[0017] Figure 5 A schematic diagram of the structure of an optical measuring device 500 according to some embodiments of this disclosure is shown;

[0018] Figure 6(a) illustrates a schematic diagram showing that the transmittance of some embodiments of this disclosure decreases monotonically with wavelength;

[0019] Figure 6(b) illustrates a schematic diagram showing that the transmittance of some embodiments of this disclosure increases monotonically with wavelength;

[0020] Figure 7 A schematic diagram of the structure of an optical measuring device 700 according to some embodiments of this disclosure is shown;

[0021] Figure 8 A schematic diagram of the structure of an optical measuring device 800 according to some embodiments of this disclosure is shown;

[0022] Figure 9 A schematic diagram of the structure of an optical measurement system 900 according to some embodiments of this disclosure is shown;

[0023] Figure 10 A schematic diagram of the structure of an optical measurement system 1000 according to some embodiments of this disclosure is shown;

[0024] Figure 11 A schematic diagram of the structure of an optical measurement system 1100 according to some embodiments of this disclosure is shown. Detailed Implementation

[0025] The technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, not all of them. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0026] It should be understood that the terms “comprising” and “including” used in this disclosure and claims indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0027] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this disclosure. As used in this disclosure and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this disclosure and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0028] As used in this specification and claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0029] The specific embodiments disclosed herein will now be described in detail with reference to the accompanying drawings.

[0030] Figure 1 A schematic diagram of the structure of an optical measuring device 100 according to some embodiments of this disclosure is shown. Figure 1 As shown, the optical measurement device 100 may include an imaging illumination module 1, a beam splitting module 2, and at least two image sensors 3.

[0031] According to the propagation direction of the detection light signal, the imaging illumination module 1 is located downstream of the optical path of the sample to be detected and is configured to converge the detection signal beam generated by the sample to the beam splitter module 2.

[0032] Beam splitter 2, located downstream of the optical path of imaging illumination module 1, includes at least one optical element coated with an optical thin film. The transmittance and / or reflectance of the optical thin film varies monotonically with wavelength within the measurement band. Beam splitter 2 is configured to split the incident light beam into two beams, wherein at least one of the two beams is transmitted through the optical thin film to the image sensor corresponding to that beam.

[0033] At least two image sensors 3 are respectively disposed in the two optical paths split by the beam splitting module 2, wherein at least one of the at least two image sensors is configured to receive the light beam output through the optical thin film and generate image information, wherein the image information is used to calculate and generate a two-dimensional wavelength distribution map of the sample to be detected.

[0034] The statement that the transmittance and / or reflectance of the optical thin film monotonically change with wavelength within the measurement wavelength range means that when a light beam passes through the optical thin film within the measurement wavelength range, its transmittance and / or reflectance monotonically increase or decrease with wavelength. The optical thin film can be deposited on the surface of an optical element. This optical element can be a filter element or a cubic beam splitter.

[0035] Two image sensors 3, after acquiring image information, transmit the image information to a computing device (not shown in the figure). The computing device calculates and generates a two-dimensional wavelength distribution map of the sample to be tested based on the image information. The computing device can be a processor, or a computer, server, or other device configured to perform calculations. The computing device generates the two-dimensional wavelength distribution map of the sample to be tested based on the image information. For example, the wavelength distribution map can be obtained by using the inverse function of the transmittance function of a pre-calibrated optical thin film and finding the corresponding wavelength value based on the transmittance ratio. Alternatively, a wavelength calculation method based on multi-wavelength fitting or a wavelength calculation method based on machine learning can be used. Furthermore, wavelength distribution data obtained from different methods can be fused to improve the reliability and accuracy of the measurement results. For example, weighted averaging, Kalman filtering, and other methods can be used to fuse wavelength distributions calculated based on physical models and predicted by machine learning.

[0036] The embodiments disclosed herein employ an optical thin film whose transmittance and / or reflectance monotonically change with wavelength within the measurement band and a dual-path imaging optical path to convert wavelength differences into light intensity differences. Then, the wavelength distribution is inferred from the light intensity distribution, thereby effectively shortening the wavelength measurement time.

[0037] The following is combined Figure 2 The optical measurement device based on the microscope optical path provided in this disclosure is further described. Figure 2A schematic diagram of the structure of an optical measurement device 200 according to some embodiments of this disclosure is shown. The optical measurement device 200 includes an imaging illumination module 1, a beam splitting module 2, a first image sensor 31, and a second image sensor 32.

[0038] like Figure 2 As shown, the imaging illumination module 1 may include an infinite-corrected objective 11, a tube lens 12, and a light source 13. The infinite-corrected objective 11 is positioned in the optical path, and the tube lens 12 is positioned downstream of the optical path of the infinite-corrected objective 11. The infinite-corrected objective 11 can be selected from various options, such as 5X, 10X, 20X, etc. The light source 13 is positioned next to the infinite-corrected objective 11. When the optical measurement device is used for photofluorescence wavelength measurement, the light source 13 is configured as an excitation source.

[0039] In some embodiments, when the sample to be tested cannot emit light on its own and requires external energy to generate light radiation or emission, the sample to be tested can be excited to produce fluorescence by an excitation light source. The excitation light source can be configured to provide external energy to the sample to be tested to excite it to produce fluorescence radiation. For example, if the sample to be tested is a micro-LED epitaxial wafer, an external excitation light source is needed to stimulate its emission for subsequent measurement and analysis of its luminescence characteristics. For example, if the sample to be tested is a blue or green micro-LED epitaxial wafer, the light source 13 can be configured as an excitation light source with a wavelength of 340-365 nm. As another example, if the sample to be tested is a red micro-LED epitaxial wafer, the light source 13 can be configured as an excitation light source with a wavelength of 520 nm or 532 nm.

[0040] Next, continue to refer to Figure 2 The beam splitting module 2 includes a cubic beam splitter 21. The cubic beam splitter 21 is positioned downstream of the optical path of the tube mirror 12 and upstream of the optical paths of the filter element 22 and the compensation element 23. The cubic beam splitter 21 is configured to split the incident beam into two beams according to a preset splitting ratio, with each beam incident on its corresponding optical element. For example, one beam is incident on the filter element 22, and the other beam is incident on the compensation element 23.

[0041] The beam splitting module 2 also includes a filter element 22 and a compensation element 23. One surface of the filter element 22 is coated with an optical thin film whose transmittance monotonically varies with wavelength within the measurement wavelength range. The compensation element 23 is made of the same material as the filter element 22 and has the same thickness. The compensation element 23 is configured to perform optical path compensation on the incident beam and transmit the compensated outgoing beam to the corresponding second image sensor 32.

[0042] refer to Figure 3 The optical path of a typical microscope shown can aid in understanding. Figure 2 This diagram illustrates the imaging optical path of an optical measurement device based on a microscope's optical path. (Example:) Figure 3 As shown, fluorescence is generated at a certain position of the sample to be tested. The fluorescence is collimated into parallel light by the infinity calibration objective 11 and continues to propagate upward to the tube lens 12. The tube lens 12 converges the parallel light onto the image sensor to form a real image.

[0043] The optical measurement device 200 is assumed to be used to measure micro-LED epitaxial wafers, and the light source 13 in the optical measurement device 200 is configured as an excitation light source.

[0044] Excitation light emitted from light source 13 shines obliquely onto the sample to be tested from the side. Fluorescence is generated at various locations on the sample to be tested according to... Figure 3 The light beam propagates to the cubic beam splitter 21. The cubic beam splitter 21 splits the incident beam into two beams with a 50:50 splitting ratio. One beam is vertically upward along the incident direction, and the other is deflected 90° to become horizontal. In the vertical direction, the beam is incident on the filter element 22, which modulates the incident beam before exiting to the first image sensor 31. In the horizontal direction, the beam is incident on the compensation element 23, which compensates for the optical path of the incident beam before exiting to the second image sensor 32.

[0045] The transmittance of the filter element 22 varies monotonically with wavelength within the measurement band, causing different light beams within the measurement band to exhibit different transmittances after passing through the optical thin film coated on the filter element 22, thereby achieving wavelength modulation. The compensation element 23 is configured to perform optical path compensation for the incident beam to ensure that the two beams pass through the same glass and air thickness during imaging, so that the two signals have the same imaging characteristics, such as aberrations and dispersion, thus ensuring the same image quality.

[0046] Although the actual transmittance change is not a simple linear function, it can be approximated using a polynomial function. From a mathematical perspective, a polynomial function can more flexibly fit the trend of actual transmittance changing with wavelength. While not a strictly linear relationship, it can reflect the trend of transmittance changing with wavelength to a certain extent. Let's assume the polynomial function used to describe actual transmittance is expressed as:

[0047] Formula (1)

[0048] Where λ represents wavelength; t0 represents transmittance at wavelength λ = 0 nm; a1 represents the slope of the straight line formed by the change of transmittance with wavelength λ; a2 represents the coefficient of the quadratic power function of transmittance with wavelength λ; and a3 represents the coefficient of the cubic power function of transmittance with wavelength λ.

[0049] As shown in Figure 4(a), the polynomial function describing the true transmittance based on formula (1) shows a monotonically increasing trend with increasing wavelength within a certain measurement wavelength range (e.g., 400nm to 700nm). Designing a filter element where the transmittance exhibits a strictly linear relationship with wavelength within the measurement wavelength range—that is, a transmittance-wavelength curve that is a straight line with a constant slope—is almost impossible. In actual manufacturing, considering various process limitations and technical challenges, the transmittance of the filter element may exhibit slope deviations and nonlinearities with wavelength changes, making it currently impossible to achieve a perfectly linear change as ideally designed.

[0050] To describe the principle of wavelength measurement, assuming that the second-order and higher-order terms in formula (1) are omitted to approximate the transmittance, the transmittance can be approximated using formula (2):

[0051] Formula (2)

[0052] In the above formula (2), λ represents the wavelength; t0 represents the transmittance when the wavelength λ is 0 nm; a1 represents the slope of the straight line formed by the change of transmittance with wavelength.

[0053] The process of calculating and generating the two-dimensional wavelength distribution map of the sample to be tested is further described below. The brightness of the image acquired by the first image sensor 31 via the filter element 22 is denoted as T(x,y). T(x,y) changes accordingly with the wavelength as the transmittance of the filter element 22 varies within the measurement wavelength range. The brightness of the image acquired by the second image sensor 32 via the compensation element 23 is denoted as R(x,y). R(x,y) is not affected by the wavelength value and is used as a reference. The relationship between the image brightness of the two beams is approximately expressed as:

[0054] Formula (3)

[0055] Where (x, y) represents a location point on the sample to be tested. Combining formulas (2) and (3), we can derive:

[0056] Formula (4)

[0057] In formula (4), λ(x,y) represents the wavelength value corresponding to position (x,y) on the sample to be tested. T(x,y) represents the brightness value of position (x,y) detected by the first image sensor 31; R(x,y) represents the brightness value of position (x,y) detected by the second image sensor 32. This disclosure simplifies wavelength measurement into image brightness calculation, enabling rapid measurement of the emission wavelength of the sample to be tested.

[0058] In some embodiments, the filter element 22 can be formed by bonding two prisms together with an inclined plane, wherein one of the prisms has an optical thin film whose transmittance varies monotonically with wavelength within the measurement band. For example, it can be deposited on the inclined plane of the prism by precision ion sputtering or vacuum evaporation. Figure 4(b) shows a schematic diagram of the tilt angle of the prism inclined plane. The tilt angle of the prism inclined plane can be designed to be 10°, that is, the tilt angle of the prism inclined plane satisfies the angle between the prism inclined plane and the incident light of the prism at 80°. The prism inclined plane with this angle design can effectively deflect the reflected light out of the detection light path.

[0059] In some embodiments, the filter element 22 may also be made of flat glass. For example, it may be made by coating an optical thin film on one surface of the flat glass, the transmittance of which varies monotonically with wavelength within the measurement band. However, the surface of the flat glass may reflect the incident light back into the original optical path, causing imaging stray light.

[0060] In some embodiments, the sample to be tested can be an OLED display sample or a micro LED. After the sample to be tested is powered on, subsequent measurement and analysis of its luminescence characteristics can be performed.

[0061] Continue to refer to Figure 2 In some embodiments, a first flat beam splitter 14 and / or a second flat beam splitter 16 may be tilted between the infinity calibration objective 11 and the tube mirror 12. The first flat beam splitter 14 is configured to reflect the light beam emitted by the light source 15 and then illuminate the sample to be tested through the infinity calibration objective 11. When the optical measurement device is used for photofluorescence wavelength measurement, the light source 15 can be configured as an excitation source.

[0062] The second flat beam splitter 16 is configured to reflect a portion of the emitted beam from the infinity calibration objective 11 and transmit it to the re-examination camera or autofocus module 17. When the second flat beam splitter 16 reflects a portion of the light to the re-examination camera, the re-examination camera is configured to repeatedly observe and inspect the sample during the experiment or test, allowing the operator to monitor the imaging of the sample, promptly identify and adjust imaging conditions such as focus and illumination intensity, to obtain a clearer and more accurate image.

[0063] When the second flat-panel beam splitter 16 reflects a portion of the light to the autofocus module, the autofocus module is configured to perform autofocus on the microscope. The autofocus module is configured to determine, based on the received light, whether the distance between the objective lens and the sample is at the optimal imaging position using a built-in focus feedback system. If not at the optimal position, the system will drive the objective lens to move along the optical axis until the optimal focus is achieved, thus ensuring image clarity and accuracy. In this way, the second flat-panel beam splitter 16 not only achieves a reasonable allocation of the light path but also simultaneously meets multiple functional requirements such as imaging, monitoring, and autofocus, improving operational convenience.

[0064] In some embodiments, to prevent excitation light from entering the image sensor, a switchable filter 18 can be provided between the infinity calibration objective 11 and the tube lens 12 to filter the light beam. The switchable filter 18 includes multiple long-pass filters, which can be selectively switched into the optical path via a mechanical element switching mechanism. Each long-pass filter is configured to filter the incident light beam so that light beams with wavelengths greater than or equal to the cutoff wavelength can pass through, while blocking light beams with wavelengths less than the cutoff wavelength. Each long-pass filter has a different cutoff wavelength. For example, when using a 365nm excitation source, the cutoff wavelength of the long-pass filter is 400nm to block wavelengths below 400nm while allowing light beams above 400nm to pass through. When using a 520nm or 532nm excitation source, the cutoff wavelength of the long-pass filter is 580nm to block wavelengths below 580nm while allowing light beams above 580nm to pass through. A mechanical component switching mechanism is configured to switch one of at least two long-pass filters into the optical path.

[0065] Since different measurement tasks may require long-pass filters with different cutoff wavelengths, the switchable filter 18 allows switching between long-pass filters with different cutoff wavelengths, thereby selecting a suitable long-pass filter with a suitable cutoff wavelength to meet diverse measurement needs. The same optical measurement system can be adapted to wavelength measurements of various types of samples. For example, when the sample is an OLED display or a micro-LED epitaxial wafer, the appropriate long-pass filter can be switched according to its luminescence characteristics and detection requirements.

[0066] In some embodiments, depending on the characteristics of the sample to be detected, the image sensor may be a monochrome area scan camera, a line scan camera, or a time-delay integration (TDI) camera, etc. This disclosure does not limit the type of camera.

[0067] The embodiments provided in this disclosure form a dual-path imaging optical path by passing the light beam emitted by the sample to be tested through a filtering optical element and a compensation element, respectively. This allows the wavelength difference to be converted into a light intensity difference, and then the wavelength distribution can be inferred from the light intensity distribution, thereby effectively shortening the wavelength measurement time.

[0068] The following is combined Figure 5 Figures 6(a) and 6(b) further illustrate the microscope-based optical measurement apparatus provided in some other embodiments of this disclosure. Figure 5 A schematic diagram of the structure of an optical measuring device 500 according to some embodiments of this disclosure is shown. Figure 2 Compared to the illustrated optical measurement device 200, the beam-splitting module 2 of the optical measurement device 500 is replaced by a first filter element 24 coated with a first optical thin film and a second filter element 25 coated with a second optical thin film. The first optical thin film has transmittance that decreases monotonically with wavelength within the measurement wavelength range, while the second optical thin film has transmittance that increases monotonically with wavelength within the measurement wavelength range.

[0069] As shown in Figure 6(a), the transmittance of the first optical film of the first filter element 24 monotonically decreases with wavelength within the measurement wavelength range (400nm to 700nm). Light with a wavelength of 400nm has a transmittance of 80% after passing through the first optical film. Light with a wavelength of 700nm has a transmittance of 20% after passing through the first optical film. As shown in Figure 6(b), the transmittance of the second optical film of the second filter element 25 monotonically increases with wavelength within the measurement wavelength range (400nm to 700nm). Light with a wavelength of 400nm has a transmittance of 20% after passing through the second optical film. Light with a wavelength of 700nm has a transmittance of 80% after passing through the second optical film. To facilitate the description of the monotonically changing relationship between the first filter element 24 coated with the first optical film and the second filter element 25 coated with the second optical film in the embodiments, the changes in transmittance of the first filter element 24 and the second filter element 25 are approximately complementary, that is, the sum of the transmittances of the first filter element 24 and the second filter element 25 is approximately 1, and the sum is approximately constant. However, in actual engineering, due to various undesirable factors, such as film absorption, inconsistency of the coating film, and nonlinearity, it is difficult to precisely maintain the sum of the transmittance of the first filter element 24 and the second filter element 25 at a constant value of 1. They usually exhibit a certain degree of fluctuation or deviation, and cannot fully achieve the theoretically ideal complementary state. However, these do not affect the monotonic change trend of transmittance and the implementation of its monotonic change principle.

[0070] In other embodiments, the transmittance of the first optical film may monotonically increase with wavelength within the measurement band, while the transmittance of the second optical film may monotonically decrease with wavelength within the measurement band.

[0071] The following is combined Figure 5 Further explanation of the working principle of wavelength measurement, and the imaging optical path of the optical measurement device 500. Figure 2 The illustrated imaging optical paths are similar. For example... Figure 5 As shown, the cubic beam splitter 21 splits the light beam into two beams according to the beam splitting ratio (e.g., 50:50). One beam passes through the first filter element 24 and enters the first image sensor 31, while the other beam passes through the second filter element 25 and enters the second image sensor 32.

[0072] Assuming an arbitrary point (x, y) on the sample to be tested, the light emitted from this point (x, y) reaches the image sensor through the optical path. The image brightness detected by each image sensor exhibits different variations due to the modulation of different filter elements. Let the image brightness acquired by the first image sensor 31 be denoted as T1(x, y), and the image brightness acquired by the second image sensor 32 be denoted as T2(x, y). By summing the two image brightnesses, we obtain the image brightness A(x, y). Since the transmittance changes of the first filter element 24 and the second filter element 25 are approximately complementary, the sum of T1(x, y) and T2(x, y) eliminates the influence of wavelength; that is, the image brightness A(x, y) is not affected by wavelength. Therefore, the image brightness A(x, y) can be used as a reference. By subtracting the two image brightnesses, we obtain the image brightness B(x, y), which is relative to... Figure 2 Regarding the image brightness detected by the first image sensor 31 after passing through the filtering light element 22, the image brightness B(x,y) is the difference between T1(x,y) and T2(x,y), which can be used to represent the double sensitivity change of image brightness affected by wavelength. Finally, through the image brightness A(x,y) (equivalent to based on... Figure 2 In the embodiments, R(x, y) serves as a reference benchmark and B(x, y) is the image brightness (equivalent to based on...). Figure 2 In the embodiments, the image brightness T(x, y) is referenced based on Figure 2 The calculation method described in the embodiments can also be used to calculate the wavelength.

[0073] This disclosed embodiment forms a dual-path imaging optical path by using two filter elements coated with optical thin films whose transmittance varies monotonically with wavelength within the measurement band. Based on differential image processing, the wavelength distribution is inferred from the light intensity distribution, which effectively shortens the wavelength measurement time and significantly improves the wavelength sensitivity of the optical measurement device.

[0074] The following is combined Figure 7 The optical measurement device based on the microscope optical path provided in this disclosure is further described. Figure 7 A schematic diagram of the structure of an optical measuring device 700 according to some embodiments of this disclosure is shown. Figure 2Compared to the illustrated optical measurement device 200, the optical measurement device 700 differs in that the beam-splitting module 2 is replaced by a customized cubic beam-splitting prism 26. An optical thin film with monotonically varying transmittance and reflectance along the wavelength within the measurement band is coated on the inclined surface of the cubic beam-splitting prism 26. For example, the transmittance of this optical thin film monotonically increases with wavelength within the measurement band, while the reflectance monotonically decreases with wavelength within the measurement band. The cubic beam-splitting prism 26 can be formed by bonding two prisms together with inclined surfaces, with an optical thin film of monotonically varying transmittance and reflectance along the wavelength within the measurement band coated on the inclined surface of one of the prisms. The angle of the inclined surface of the prism can be designed to form a 45° angle with the bottom surface of the prism.

[0075] The following is combined Figure 7 Further explanation of the working principle of wavelength measurement, imaging optical path and Figure 2 The illustrated imaging optical paths are similar. For example... Figure 7 As shown, the cubic beam splitter 25 splits the incident light beam into two beams, one of which directly enters the first image sensor 31, and the other directly enters the second image sensor 32. When the beams are incident on the optical thin film of the cubic beam splitter 25, the transmittance of the optical thin film monotonically increases with wavelength within the measurement wavelength range, while the reflectance monotonically decreases with wavelength within the measurement wavelength range. In some embodiments, the transmittance of the optical thin film monotonically decreases with wavelength within the measurement wavelength range, while the reflectance monotonically increases with wavelength within the measurement wavelength range. Figure 7 The optical measuring device 700 shown uses a different method for calculating and generating image information than... Figure 5 The calculation and processing method of the optical measuring device 500 shown is similar; see [link to relevant documentation]. Figure 5 The details regarding image information calculation and generation processes will not be elaborated here.

[0076] Compared to Figure 2 The optical measurement device 200 shown, and the optical measurement device 700 proposed in this embodiment, form a dual-path imaging optical path by setting an optical thin film on a cubic beam splitter whose transmittance and reflectance change monotonically with wavelength within the measurement band, so as to realize the wavelength distribution by inversely inferring the wavelength distribution from the light intensity distribution, and can also effectively shorten the wavelength measurement time.

[0077] Figure 8 A schematic diagram of the structure of an optical measuring device 800 according to some embodiments of this disclosure is shown. Figure 2Compared to the illustrated optical measuring device 200, the imaging illumination module 1 of the optical measuring device 800 employs a different design. In the optical measuring device 800, the imaging illumination module 1 replaces the cubic beam splitter 191 and the imaging lens 192. The cubic beam splitter 191 is positioned in the imaging optical path, splitting the detection signal beam emitted from the sample to be tested. The imaging lens 192, positioned downstream of the optical path of the cubic beam splitter 191, is configured to converge the incident beam into an imaging beam.

[0078] like Figure 8 As shown, the imaging illumination module 1 also includes a light source 13 and / or a light source 15, a switchable filter 18, etc. The working principle of the switchable filter 18 is similar to... Figure 2 The descriptions are the same, so I won't repeat them here.

[0079] The light source 13 in the optical measuring device 800 is configured as an excitation source, shining obliquely onto the sample to be tested from the side. The fluorescence excited from the sample is transmitted through the cubic beam splitter 191 to the imaging lens 192. The imaging lens 192 focuses the beam onto a switchable filter 18 located in the optical path. A long-wavelength filter in the switchable filter 18 filters the beam, and the filtered beam is then incident on the beam splitter module 2. The beam splitter module 2 can employ... Figure 2 or Figure 5 or Figure 7 The described beam splitter module, and the internal optical path of beam splitter module 2 can be found in the section on... Figure 2 , Figure 5 or Figure 7 The relevant descriptions will not be repeated here.

[0080] and Figure 2 Compared to the illustrated optical measurement device 200, the imaging illumination module 1 of the optical measurement device 800 uses a cubic beam splitter prism 191 and an imaging lens 192 to achieve imaging. In the imaging optical path, the magnification can be changed by adjusting the distance L between the imaging illumination module 1 and the beam splitter 2 and the distance WD between the imaging illumination module 1 and the sample to be tested, thereby flexibly meeting the imaging requirements of different magnifications.

[0081] In some embodiments, the imaging lens 192 may be a Gaussian lens, an FA lens, or the like.

[0082] In some embodiments, the cubic beam splitter 191 can be replaced by a flat beam splitter for introducing coaxial illumination or excitation light sources.

[0083] The optical measurement device 800 provided in this embodiment adopts a technical solution based on an independently designed imaging lens, which is suitable for low-magnification imaging, such as optical magnification less than 5X.

[0084] Some embodiments disclosed herein also provide an optical measurement system incorporating Automated Optical Inspection (AOI) functionality to effectively address the problems of large space occupation, low switching efficiency, and high cost caused by the need for separate equipment for emission wavelength measurement and automated optical inspection. Specifically, the automated optical inspection is used to image and detect the reflected or scattered light from the sample.

[0085] The following is combined Figure 9 The optical measurement system 900 provided in this embodiment will be described in detail. Figure 9 The optical measurement system 900 is shown to be based on, for example... Figure 2 The optical measurement device 200 is described, and its beam-splitting module 2 is improved by adding a bright-field / dark-field detection optical element group. The bright-field / dark-field detection optical element group includes a first filter 281, a second filter 282, a first optical path mode switching mechanism 283, and a second optical path mode switching mechanism 284. The first optical path mode switching mechanism 283 and the second optical path mode switching mechanism 284 are configured to synchronously respond to a control signal and perform a switching operation. When the first optical path mode switching mechanism 283 switches the filter element 22 into the optical path and the second optical path mode switching mechanism 284 switches the compensation element 23 into the optical path, the optical measurement system 900 is configured to measure the two-dimensional distribution of the emission wavelength of the sample to be tested. When the first optical path mode switching mechanism 283 switches the first filter 281 into the optical path and the second optical path mode switching mechanism 284 switches the second filter 282 into the optical path, the optical measurement system 900 is configured to perform automatic bright-field / dark-field optical detection on the sample to be tested.

[0086] The working principle of the optical measurement system 900 will be explained below, taking a micro-LED epitaxial wafer as an example. Figure 9 As shown, when the optical measurement system 900 is in wavelength measurement mode, the light source 13 is configured as an excitation source, tilting to illuminate the sample to be tested to generate fluorescence. Similar to the aforementioned... Figure 2 , Figure 5 and Figure 8 The optical measuring device described is the same, and the working principle of measuring wavelength can be found in the previous related descriptions.

[0087] When the optical measurement system 900 is in AOI working mode, the light source 13 is configured as a 450nm illumination source, illuminating the sample to be tested at an angle to form a dark field illumination path. The light source 15 is configured as a 650nm illumination source, and the illumination light is coaxially incident on the sample to be tested through the first flat beam splitter 14 to form a bright field illumination path.

[0088] The first filter 281 and the second filter 282 in the optical path filter the two beams output by the cubic beam splitter 21, so that the image sensor 31 and the image sensor 32 can synchronously detect the dark field image or the bright field image.

[0089] Light source 13 illuminates the sample under test at an angle. The beam emitted by the sample propagates along the imaging optical path to the cubic beam splitter prism 21, where it is split into two beams. One beam passes through filter 281 and enters the first image sensor 31, while the other passes through filter 282 and enters the second image sensor 32. Filter 281 allows bright field light (650nm) to pass through while blocking dark field light (450nm); filter 282 allows dark field light to pass through while blocking bright field light. Therefore, a dark field image can be acquired at the second image sensor 32.

[0090] Light source 15 illuminates the sample under test as a coaxial light source through infinity calibration objective lens 11. The beam emitted from the sample propagates along the imaging optical path to cubic beam splitter prism 21, where it is split into two beams. One beam passes through filter 281 and enters the first image sensor 31, while the other passes through filter 282 and enters the second image sensor 32. Filter 281 allows bright-field light (650nm) to pass through while blocking dark-field light (450nm), thus the first image sensor 31 acquires a bright-field image. Then, the dark-field image or the bright-field image is input into a computing device (not shown in the figure). The computing device processes the data to obtain the bright-field / dark-field AOI detection results.

[0091] In some embodiments, the first optical path mode switching mechanism 283 and the second optical path mode switching mechanism 284 may be mechanical switching mechanisms.

[0092] In some embodiments, the first filter 281 may be a bandpass filter or a long-wavelength filter. The second filter 282 may be a bandpass filter or a short-wavelength filter.

[0093] In some embodiments, the beam splitter 2 can employ... Figure 5 , Figure 8 The switching process of the first filter element 24 and the second filter element 25 shown is the same as the switching operation described above, and will not be repeated here.

[0094] The embodiments disclosed herein utilize an optical measurement system with dual operating modes to meet different detection needs and adapt to various detection tasks.

[0095] Figure 10 A schematic diagram of the structure of an optical measurement system 1000 according to some embodiments of this disclosure is shown. The internal structure of the imaging illumination module 1 in the optical measurement system 1000 differs from that in the optical measurement system 900. Specifically, the imaging illumination module 1 employs... Figure 8 The internal structure shown. Figure 10 The optical measurement system 1000 shown is Figure 9 The dual-mode operating principle of the optical measurement system 900 shown is the same, the difference being that... Figure 10 The optical measurement system 1000 shown uses an independently designed imaging lens, which is suitable for low-magnification imaging, such as when the optical magnification is less than 5X.

[0096] In some embodiments, when the imaging illumination module 1 employs an independent imaging lens scheme, a dome light source can also be used as the illumination or excitation light source. Since the imaging lens has a larger object distance (WD) compared to the microscope objective, a dome light source can be installed below the imaging lens. For example, when the first image sensor 31 and the second image sensor 32 are line scan cameras or TDI cameras, a line scan dome light source can be selected.

[0097] Figure 11 A schematic diagram of the structure of an optical measurement system 1100 according to some embodiments of this disclosure is shown. For example... Figure 11 As shown, the optical measurement system 1100 includes an optical measurement device 1101 and a processor 1102. The optical measurement device 1101 can employ, for example... Figure 2 , Figure 5 , Figure 8 The optical measuring device described, or such as Figure 9 or Figure 10 The optical measurement system described herein includes a processor 1102 that is communicatively connected to an image sensor and configured to calculate and generate a two-dimensional wavelength distribution map of the sample to be tested based on image information from the image sensor. The specific calculation and generation process can be found in the descriptions of the preceding embodiments and will not be repeated here.

[0098] In summary, the embodiments disclosed herein, through the innovative combination of an optical thin film whose transmittance and / or reflectance monotonically vary with wavelength within the measurement band and a dual-path synchronous imaging architecture, effectively shorten the wavelength measurement time compared to traditional spectral scanning methods. Furthermore, the dual-mode optical measurement system meets different detection requirements to adapt to various detection tasks.

[0099] Considering the uneven illumination of the sample surface by the light source, the differences in light transmission efficiency of the imaging optical path at different field-of-view positions, and the differences in transmission efficiency of the imaging optical path for different wavelengths, all of these factors can affect the accuracy of wavelength measurement results. Therefore, some embodiments of this disclosure also provide a calibration method for an optical measurement system. By setting up calibration devices such as a diffuse reflector, an integrating sphere light source, and a spectrometer, these problems can be addressed to improve the accuracy of the measurement results.

[0100] Assume the sample to be tested is placed on the sample stage of the optical measurement system, and a diffuse reflector is placed next to the sample. Before measuring the sample, the sample stage is moved to move the diffuse reflector below the objective lens or imaging lens, and an image is captured by an imaging camera to obtain the reflection image of the diffuse reflector. The reflection image carries the light intensity distribution information of the excitation source or illumination source, which can be used for uniformity calibration of the excitation source or illumination source.

[0101] The integrating sphere light source is placed below the objective lens or imaging lens of the optical measurement system, with the sphere's exit port facing the objective lens or imaging lens. The light intensity at the exit port of the integrating sphere light source can be considered uniform, which can be used to calibrate the transmission efficiency differences of the imaging optical path at various fields of view. Through its uniform illumination characteristics, the integrating sphere light source can ensure the elimination of brightness unevenness or efficiency deviations caused by optical path design or environmental factors during imaging at different field-of-view positions.

[0102] The integrating sphere light source also includes three monochromatic light sources (RGB), which are connected to the spectrometer via optical fibers. Different monochromatic light sources on the integrating sphere are sequentially activated, such as the RGB sources. The imaging optical path is used to image the light outlet of the integrating sphere, acquiring the imaging intensity images of each monochromatic light at various points within the imaging field of view. Simultaneously, the wavelength of each monochromatic light source is precisely measured using the spectrometer. The imaging intensity images of each monochromatic light are analyzed to calculate the relative transmission efficiency at each point within the imaging field of view. Then, a calibration model is established based on the relative transmission efficiency data to eliminate the influence of differences in the transmission efficiency of the imaging optical path on the measurement results. The spectrometer can be used to accurately measure wavelengths to calibrate the deviation of the imaging optical path's transmission efficiency for different wavelengths of light. By using the combination of RGB light sources and a spectrometer, the response characteristics of the imaging system at different wavelengths can be calibrated, thereby eliminating deviations caused by inconsistent responses of optical components to different wavelengths.

[0103] The above calibration method can solve problems such as the non-uniformity of the excitation or illumination source, the difference in transmission efficiency of the imaging optical path at each field of view, and the difference in transmission efficiency of the imaging optical path at each wavelength.

[0104] While numerous embodiments of this disclosure have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and intent of this disclosure. It should be understood that various alternatives to the embodiments of this disclosure described herein may be employed in the practice of this disclosure. The appended claims are intended to define the scope of this disclosure and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. An optical measuring device, characterized in that, The optical measuring device includes: The beam splitting module includes at least one optical element coated with an optical thin film, the transmittance and / or reflectance of which vary monotonically with wavelength within the measurement band. At least two image sensors are respectively disposed downstream of the optical path of the beam splitter module. At least one of the at least two image sensors is configured to receive a light beam output through the optical thin film and generate image information, wherein the image information is used to calculate and generate a two-dimensional wavelength distribution map of the sample to be detected. The beam splitting module also includes a cubic beam splitting prism, which is disposed upstream of the optical path of the optical element and is configured to split the incident beam to be detected into two beams, at least one of which is transmitted via the optical thin film to the image sensor corresponding to that beam.

2. The optical measuring device according to claim 1, characterized in that, When the optical element is a filter element, the beam splitting module further includes at least one compensation element. The compensation element is made of the same material as the filter element and has the same thickness as the filter element. The other beam of the two beams is transmitted to the image sensor corresponding to that beam via the compensation element.

3. The optical measuring device according to claim 1, characterized in that, The optical element includes a first filter element and a second filter element respectively disposed on the optical paths of the two beams. The first filter element is coated with a first optical thin film, and the second filter element is coated with a second optical thin film. The transmittance of the first optical thin film increases monotonically with wavelength within the measurement wavelength range, and the transmittance of the second optical thin film decreases monotonically with wavelength within the measurement wavelength range; or the transmittance of the first optical thin film decreases monotonically with wavelength within the measurement wavelength range, and the transmittance of the second optical thin film increases monotonically with wavelength within the measurement wavelength range. At least one of the two light beams is transmitted to the image sensor corresponding to that light beam via the optical thin film, including: one of the two light beams is transmitted to the image sensor corresponding to that light beam via the first optical thin film; the other light beam is transmitted to the image sensor corresponding to that light beam via the second optical thin film.

4. The optical measuring device according to claim 1, characterized in that, The optical measurement device further includes an imaging illumination module, which is located upstream of the optical path of the beam splitter and is configured to converge the detection signal beam generated by the sample to be tested to the beam splitter.

5. The optical measuring device according to claim 4, characterized in that, The imaging illumination module includes at least one infinity calibration objective and a tube lens, or the imaging illumination module includes a cubic beam splitter and an imaging lens.

6. The optical measuring device according to claim 5, characterized in that, When the imaging illumination module includes a cubic beam splitter and an imaging lens, the optical measurement device further includes a dome light source, which is disposed below the cubic beam splitter.

7. The optical measuring device according to claim 1, characterized in that, The cubic beam splitter is formed by bonding two prisms together with an inclined plane. The optical thin film is coated on the inclined plane of either of the two prisms. The transmittance of the optical thin film increases monotonically with wavelength within the measurement wavelength range, and the reflectance of the optical thin film decreases monotonically with wavelength within the measurement wavelength range; or the transmittance of the optical thin film decreases monotonically with wavelength within the measurement wavelength range, and the reflectance of the optical thin film increases monotonically with wavelength within the measurement wavelength range.

8. An optical measurement system, characterized in that, The optical measurement system includes: an optical measurement device as described in any one of claims 1-7 and a processor communicatively connected to the image sensor, the processor being configured to: calculate and generate a two-dimensional wavelength distribution map of the sample to be tested based on image information from the image sensor.

9. An optical measurement system, characterized in that, The optical measurement system includes: an optical measurement device as described in any one of claims 1-6 and a bright field / dark field detection optical element group disposed in the beam splitting module, wherein the bright field / dark field detection optical element group includes a first filter, a second filter, a first optical path mode switching mechanism, and a second optical path mode switching mechanism; When the optical element is a filter element and the beam splitting module further includes at least one compensation element, the first optical path mode switching mechanism and the second optical path mode switching mechanism are configured to synchronously respond to the control signal and perform the following switching operations: When the first optical path mode switching mechanism switches the filter element into the optical path and the second optical path mode switching mechanism switches the compensation element into the optical path, the optical measurement system is configured to measure the two-dimensional distribution of the emission wavelength of the sample to be tested; or... When the first optical path mode switching mechanism switches the first filter into the optical path and the second optical path mode switching mechanism switches the second filter into the optical path, the optical measurement system is configured to perform automatic bright-field / dark-field optical detection on the sample to be tested; or... When the optical element includes a first filter element and a second filter element respectively disposed on the optical paths of the two beams, the first filter element is coated with a first optical thin film, and the second filter element is coated with a second optical thin film, the first optical path mode switching mechanism and the second optical path mode switching mechanism are configured to synchronously respond to the control signal and perform the following switching operation: When the first optical path mode switching mechanism switches the first filter element into the optical path and the second optical path mode switching mechanism switches the second filter element into the optical path, the optical measurement system is configured to measure the two-dimensional distribution of the emission wavelength of the sample to be tested; or... When the first optical path mode switching mechanism switches the first filter into the optical path and the second optical path mode switching mechanism switches the second filter into the optical path, the optical measurement system is configured to perform automatic bright field / dark field optical detection on the sample to be tested.

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