Optical property inspection equipment

Abstract

The apparatus includes a detector (2) that receives light emitted from the object under test (900), a drive device that drives and positions the measurement position of either the object under test (900) or the detector (2), and an optical axis adjustment unit (4) that performs a search calculation for a position among the measurement positions at which the maximum amount of light is obtained from the object under test (900) based on position information (Ip) indicating the measurement position obtained from the drive device and an electrical signal (Se) output from the detector (2) each time positioning is performed, and adjusts the optical axis of the object under test (900).The optical axis adjustment unit (4) performs the search calculation using a regression method based on nonlinear modeling, taking into account the amount of positional deviation caused by the drive device.

Description

[Technical field]

[0001] The present disclosure relates to an optical property inspection apparatus. [Background technology]

[0002] When inspecting the optical characteristics of optical semiconductor devices such as semiconductor lasers and Mach-Zehnder modulators, it is necessary to precisely align the optical axis of the detector with respect to the emission end face. However, the optical axis position differs every time inspection is performed due to variations in the characteristics of the device and variations in the alignment accuracy of the device within the inspection equipment.

[0003] For example, when adjusting the optical axis between the output end face of an optical semiconductor element and a detector, the optical signal emitted from the optical semiconductor element is received by the detector, the received optical signal is converted into an electrical signal, etc., and the optical axis is adjusted while checking the signal strength. Therefore, when performed manually, there are issues that the inspection results depend on the skill of the operator and that optical axis adjustment takes time.

[0004] On the other hand, it is possible to operate the motor by program and automatically adjust the optical axis, but in the general method of obtaining the point where the maximum light intensity is obtained by performing a full search within a set range, the signal is obtained in detail even in unnecessary ranges, which increases the time for adjusting the optical axis. Alternatively, a method of shortening the time for adjusting the optical axis can be considered using an algorithm such as the hill climbing method. However, when the element before inspection, i.e., the characteristics of the element, are unknown, there is not necessarily one peak, and a method such as the hill climbing method may result in a locally optimal solution.

[0005] Therefore, it is conceivable that a regression method such as Gaussian process regression (see, for example, Patent Document 1) can be used to avoid convergence at a local optimum point and to find a global optimum point with fewer steps. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-85801 A (paragraph 0060, Fig. 12, Fig. 14) Summary of the Invention [Problem to be solved by the invention]

[0007] However, while typical regression methods take into account noise in the objective variable, they do not necessarily reach the global optimum when there is uncertainty in the explanatory variables, such as the motor's repeatability.

[0008] The present disclosure is devised to solve the above-mentioned problems, and aims to provide an optical property inspection device that can avoid convergence at a local optimum point and adjust the optical axis using a global optimum point obtained with fewer steps. [Means for solving the problem]

[0009] The optical characteristic inspection device of the present disclosure includes a detector that receives light emitted from an optical semiconductor element. the angular position of the exit surface of the exit light, the position along the optical axis of the exit light, the position in the direction perpendicular to the optical axis, The detector a position along the optical axis with respect to the exit surface, and a position in a direction perpendicular to the optical axis Any of of Measurement position As the optical axis adjustment unit performs the search calculation using a regression method with nonlinear modeling, taking into account a positional deviation caused by the drive unit; and the optical axis adjustment unit is provided with a convergence determination unit that determines a convergence state of the search calculation, and a re-search position setting unit that sets a re-search position from among a plurality of positions that may show the maximum light amount by weighting using variance or allocating using random numbers when the convergence determination unit determines that convergence has occurred to a certain extent. Effect of the Invention

[0010] According to the optical property inspection device disclosed herein, convergence at a local optimum point can be avoided by performing processing that takes into account uncertainty in the explanatory variables, thereby making it possible to obtain an optical property inspection device that is capable of adjusting the optical axis by finding the global optimum point with fewer steps. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram for explaining a configuration of an optical property inspection apparatus according to a first embodiment. [Diagram 2] 1 is a diagram simulating a two-dimensional distribution of the amount of light emitted from an optical semiconductor element to be inspected. [Diagram 3] 3A and 3B are diagrams showing the transition of search points in optical axis adjustment by full search and the transition of search points in optical axis adjustment using Gaussian process regression, respectively. [Figure 4] 4A and 4B are diagrams showing the initial stage and further progress of the search for measured values ​​in optical axis adjustment using Gaussian process regression and the range of twice the predicted mean value and standard deviation based on the measured values. [Diagram 5] FIG. 13 is a diagram showing a state at a stage where search has been completed to a certain extent for measured values ​​in optical axis adjustment using Gaussian process regression and a range twice the predicted average value and standard deviation based on the measured values. [Figure 6] 4 is a flowchart for explaining the operation of the optical property inspection apparatus according to the first embodiment. [Figure 7] 5 is a flowchart for explaining an operation in an optical axis adjustment step in the operation of the optical property inspection apparatus according to the first embodiment. [Figure 8] FIG. 2 is a block diagram showing a hardware configuration of a portion that executes arithmetic processing of the optical property inspection apparatus according to the first embodiment. [Figure 9] FIG. 2 is a block diagram for explaining a configuration of an optical property inspection apparatus according to a first modified example of the first embodiment. [Figure 10] FIG. 13 is a block diagram for explaining a configuration of an optical property inspection apparatus according to a second modified example of the first embodiment. [Figure 11] FIG. 11 is a block diagram for explaining the configuration of an optical property inspection apparatus according to a second embodiment. [Figure 12] FIG. 13 is a block diagram for explaining a configuration of an optical property inspection apparatus according to a modified example of the second embodiment. [Figure 13] FIG. 11 is a block diagram for explaining a configuration at a pre-stage of an optical property inspection apparatus according to a third embodiment. [Figure 14] FIG. 11 is a block diagram for explaining a configuration at a later stage of an optical property inspection apparatus according to a third embodiment. [Figure 15] 13 is a flowchart for explaining the operation of the optical property inspection apparatus according to the third embodiment. [Figure 16] FIG. 13 is a block diagram for explaining the configuration of an optical property inspection apparatus according to a first modified example of the third embodiment. [Figure 17] FIG. 13 is a block diagram for explaining the configuration of an optical property inspection apparatus according to a second modified example of the third embodiment. [Figure 18] FIG. 13 is a block diagram for explaining the configuration of an optical property inspection apparatus according to a fourth embodiment. [Figure 19] FIG. 13 is a block diagram for explaining the configuration of an optical property inspection apparatus according to a first modified example of the fourth embodiment. [Figure 20] FIG. 13 is a block diagram for explaining the configuration of an optical property inspection apparatus according to a second modified example of the fourth embodiment. [Figure 21] FIG. 13 is a block diagram for explaining the configuration of an optical property inspection apparatus according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In the optical property inspection device disclosed herein, in addition to light-emitting elements such as semiconductor lasers that emit light themselves and function as light sources, modulators such as Mach-Zehnder modulators are inspected. However, the following description will be given using an example in which a semiconductor laser is used as the inspected object, but when a modulator is the target, a separate light source is provided to input an optical signal to the modulator.

[0013] Embodiment 1 Figures 1 to 7 are intended to explain the configuration and operation of the optical property inspection apparatus of embodiment 1, and Figure 1 is a block diagram simulating the spatial arrangement of an object to be inspected and a part that detects light, in order to explain the configuration of the optical property inspection apparatus.

[0014] Figure 2 is a diagram simulating the two-dimensional distribution of the amount of light emitted from an optical semiconductor element, which is the object to be inspected (tested object), on a plane perpendicular to the optical axis, with the light appearing whiter as the light intensity increases. Figure 3A is a diagram showing the progression of search points during optical axis adjustment by full search, and Figure 3B is a diagram showing the progression of search points during optical axis adjustment using Gaussian process regression.

[0015] Also, Fig. 4A, Fig. 4B, and Fig. 5 show the measured value (x), the predicted average value (solid line) based on the measured value, and the range of twice the standard deviation (shaded) in the optical axis adjustment using Gaussian process regression, Fig. 4A shows the initial stage of the search, Fig. 4B shows the state after the search has progressed further, and Fig. 5 shows the state when the search has been completed to a certain extent as the stage for starting a re-search in the process considering the uncertainty. Fig. 6 is a flowchart for explaining the overall operation of the optical property inspection device, and Fig. 7 is a flowchart for explaining the operation in the optical axis adjustment process.

[0016] As shown in FIG. 1, the optical property inspection device 1 in embodiment 1 is a device that aligns (adjusts the optical axis) a detector 2 that detects light with the position of the optical axis Ao (optical axis position) with respect to the emission end face of an optical semiconductor element, which is an object to be inspected 900, and inspects the optical properties of the object to be inspected 900.

[0017] For the optical semiconductor element being the object under test 900, an object under test fixing jig 6 for positioning and fixing the object under test 900 and an object under test operating power supply 7 for operating (emitting light or modulating) the object under test 900 are provided. The object under test fixing jig 6 may have a counterbore in accordance with the maximum tolerance of the optical semiconductor element. By adopting such a design, it is possible to limit the optical axis adjustment range, and it is expected that the regression calculation will converge faster. Furthermore, if necessary for carrying out the inspection of the optical semiconductor element, an element for controlling the temperature, such as a Peltier element, may be provided. Furthermore, if it is difficult to fix the element position due to the usage environment, a mechanism for vacuum suction may be provided.

[0018] The device is equipped with a detector 2 arranged so that its detection surface faces the emission surface of the inspected object 900, a detector drive device 3 that mechanically drives the detector 2, and a photoelectric converter 5 that converts an optical signal So output by the detector 2 into an electrical signal Se. The device is also equipped with an optical axis adjustment unit 4 that sets a search point based on the amount of light (electrical signal Se) detected by the detector 2 and position information Ipd of the detector 2 output from the detector drive device 3, and controls the drive of the detector drive device 3 (outputs a drive signal Scd). The device is also equipped with an inspection control unit 8 that controls the overall operation of the optical property inspection.

[0019] For example, an optical fiber, a photodiode, a lensed fiber, a bulb-tipped fiber, etc. are used for the detector 2. In addition, it is preferable to appropriately select a material for the detector 2 in accordance with the wavelength of the emitted light from the object 900 to be inspected.

[0020] The detector driver 3 drives the detector 2 in the horizontal direction (perpendicular to the optical axis Ao) and in the emission direction relative to the emission surface of the inspected object 900. For example, a stepping motor or the like is used to drive the detector driver 3. Since the optical axis position of a laser diode or the like is generally about 10 μm, it is preferable to use a device with a finer resolution than that. For directions that require more precise adjustment, a combination of stepping motors or the like with different resolutions for the same direction may be used.

[0021] The optical axis adjustment unit 4 includes an optimum position search unit 41 that uses Gaussian process regression by nonlinear modeling using a kernel function and sets a search point based on the electrical signal Se and position information Ipd, and a variable processing unit 42 that processes explanatory variables in consideration of uncertainty. It also includes a convergence determination unit 43 that determines the state of convergence in two stages, quasi-convergence and complete convergence, and a re-search position setting unit 44 that sets a re-search position when quasi-convergence is determined.

[0022] By operating the detector driving device 3 in cooperation with the optical axis adjustment unit 4 described above, it is possible to move the detector 2 to coordinates where a high output of light emitted from the inspection object 900 can be obtained. When searching for the optimal point, for example, the position coordinates (position information Ipd: for example, XYZ) are used as explanatory variables, and the light amount (electrical signal Se) is used as a target variable to search for and set the optimal position. Also, a function for adjusting the angle may be added to the detector driving device 3. In that case, the angle information is also added to the explanatory variables.

[0023] Gaussian process regression is generally linear. However, when multiple peaks exist, such as in the case of optical semiconductor elements, linear modeling, including Gaussian process regression, is unsuitable, and Gaussian process regression, which uses a kernel function to perform nonlinear modeling, is desirable.

[0024] Here, before explaining the operation of the optical property inspection device 1, we will explain the difference between a general search (full search) and Gaussian process regression, as well as the challenges and setting of search points using general Gaussian process regression by performing variable processing taking into account uncertainties.

[0025] Consider the case where the light amount distribution emitted from an optical semiconductor element, which is the object 900 to be inspected, has two peaks due to a peak split as shown in Fig. 2. For example, when the optical axis adjustment is performed by a full search, the search points (white circles) are set sequentially so as to cover the entire area, as shown in Fig. 3A. In this case, too, it is considered that a method of re-searching in detail for points closer to the peak is generally used.

[0026] On the other hand, when the optical axis is adjusted by Gaussian process regression, the area near the boundary (periphery) is searched first, and then the point with the highest expected value is set as the search point, as shown in Figure 3B. This behavior is expected to lead to a search point where high light intensity can be obtained with fewer search points than with a full search.

[0027] Although this type of Gaussian process regression is used, even in general Gaussian process regression, noise in the objective variable is taken into consideration when designing. However, in cases involving motor drive such as this one, it is necessary to consider a certain amount of noise in the explanatory variables as well, such as uncertainty typified by the repeatability of a stepping motor.

[0028] Considering noise in such input variables is considered a difficult problem in statistics, and simply applying Gaussian process regression may not be enough to achieve stable, accurate, and high-speed adjustment. In other words, although the optical axis adjustment can be completed at a relatively high speed, the calculation may not converge at the point where maximum light intensity is obtained because the input contains noise.

[0029] Therefore, in the optical property inspection device 1 disclosed herein, the drawbacks of Gaussian process regression are overcome by adding processing (variable processing by the variable processing unit 42) that takes into account that the position information (explanatory variable) of the stepping motor is probabilistically distributed depending on the repeatability and reproducibility of the stepping motor.

[0030] The future position deviation of the stepping motor is considered to have a Markov property because it is considered to be strongly dependent on the current motor position. Therefore, the difficulty can be avoided by adding a process that considers the Markov property to the explanatory variables. For example, when the optical axis search is completed to a certain extent (semi-convergence), an algorithm is provided that performs a process (process A) of probabilistically stopping at a position considered to be the optimal point several times. Alternatively, an algorithm is provided that performs a process (process B) of varying the probability of stopping at a position several times depending on the expected value at which the maximum light intensity is obtained.

[0031] The quasi-convergence is set as the timing when it is confirmed that there is no point where a higher expected value can be obtained within the range where the search and variance calculation have converged at the present time. In other words, it is the timing when the maximum light amount can be expected to be obtained by re-searching, and the timing of the quasi-convergence will be explained using Fig. 4A to Fig. 5. Note that, in the calculations (average prediction values) in the figures, the calculations are all performed taking into account noise in the objective variables, so the function (solid line) estimated from the measured data does not necessarily pass through the measurement points (x).

[0032] At the stage shown in Figure 4A, the number of searches is still insufficient, and it is not clear whether the x (explanatory variable) at which the maximum y (objective variable) is obtained is in the range of -3 to -2 or 1 to 2. In addition, the range of values ​​that needs to be searched has not been narrowed sufficiently. At this point, there is a high possibility that re-searching a point that has already been searched will be a waste of time, so it is not judged as quasi-convergence here and re-searching is not performed.

[0033] If we continue searching from here and reach the state shown in Figure 4B, we can see that the maximum point of y is likely to be in the range of x = (1.5 to 2.5). However, the data for x = 2 here contains an error due to the repeatability of the stepping motor. At this point, we can minimize the effect of the repeatability of the stepping motor by adding processing such as re-searching.

[0034] In addition, the operation of Process A: "probabilistically visiting the position thought to be the optimal point a certain number of times" or Process B: "variable probability of visiting the position a certain number of times based on the expected value at which maximum light intensity is obtained" that is performed when quasi-convergence is reached will be explained using the case shown in Figure 5.

[0035] In this case, we can see that the average value + 2σ is likely to show the maximum value in two places, near x = -3.0 and near x = 2.0. However, the reason that the maximum value is likely to be shown at x = -3.0 is simply because the variance is large. Therefore, in this case, the operation of Process B would be to weight the variance and design it so that it is easier to re-search for x = 2.0, which has a smaller variance.

[0036] Process A corresponds to the operation of probabilistically re-searching for X=2.0 or X=-3.0 (which one to go to is determined by random numbers, etc.) at the timing of quasi-convergence. It is believed that this probability will be set optimally by conducting experiments using actual objects. For example, the optimal probability is considered to be the probability that is obtained by changing the probability using various measurement objects, performing automatic optical axis adjustment, realizing peak adjustment, and minimizing takt time. Also, rather than fixing the probability, it is also possible to devise a way to affect the re-search probability by changing the re-search point or the magnitude of variance in its vicinity in addition to the above-mentioned probabilities.

[0037] Next, an operation that takes the Markov property into consideration will be described. For example, in the above example, suppose that the point x=2.0 is searched for by moving in the direction to increase x. In this case, if moving from x=0.0 in the direction to increase x and moving from x=4.0 in the direction to decrease x, the position accuracy is considered to differ due to inertia, considering physics. From x=0.0, due to inertia, it is easy to stop at a place slightly larger than x=2.0, and from x=4.0, it is easy to stop at a place slightly smaller than x=2.0. It is considered that the effect of noise on the objective variable can be minimized by the operation (processing) that assumes the tendency of position deviation due to inertia.

[0038] As described above, the operation of the optical property inspection device equipped with the optical axis adjustment unit 4 configured to perform additional processing such as re-searching for the Gaussian process regression that performs nonlinear modeling by using the kernel function will be described with reference to the flowcharts in Figs. 6 and 7.

[0039] 6, the object under test 900 is positioned and fixed on the object under test fixing jig 6 or the like (step S100). This operation may be performed manually using tweezers or the like, or automatically using a suction collet or the like based on a command from the inspection control unit 8. Next, the object under test 900 is connected to an object under test operating power supply 7 for operating the object under test 900 (step S110). This connection is performed by bringing a probe or the like into contact with the electrodes of the object under test 900.

[0040] After the object under test 900 is connected to the object under test operating power supply 7, the object under test operating power supply 7 is turned on to operate the object under test 900 (step S120). This operation may also be performed manually or automatically based on a command from the inspection control unit 8. In this case, the operating conditions are not important, but it is preferable to operate the object under conditions that allow continuous light emission (or modulation) when performing optical axis adjustment.

[0041] Next, as described above, the light emitted from the object under test 900 is received by the detector 2 while sequentially setting search points, and the process of adjusting the optical axis is performed (step S200). In the optical axis adjustment process, as shown in Fig. 7, variable processing is first performed considering noise in the objective variable (step S210). Then, using Gaussian process regression in which nonlinear modeling is performed using a kernel function, variance calculation is performed based on the setting of search points and the light intensity measurement results when moving to the set search points (step S220).

[0042] At this time, the detector 2 is moved to a position (driving signal Scd) specified by the optimum position search unit 41 using the detector driving device 3, whereby the detector 2 is moved to a position where a statistically high output can be expected to be obtained. Note that in step S220, the motor drive may be controlled assuming a position shift due to inertia, taking into consideration the above-mentioned Markov property.

[0043] The convergence state is judged (step S230), and if it is judged that convergence has not occurred, the process proceeds to step S220 and a re-search is performed. On the other hand, if it is judged that the optical axis search has been completed to a certain extent, that is, that the search has been quasi-converged, a re-search position is set by the above-mentioned processes A and B (step S250), and the process proceeds to step S220 and a re-search is performed. If it is judged that convergence has occurred completely, the optical axis adjustment process is terminated.

[0044] When the optical axis adjustment process is completed and the optical axis is adjusted, an optical characteristic inspection is performed (step S300: FIG. 6). In the optical characteristic inspection, the output of the inspected object operating power supply 7 is changed according to the inspection item, or the detector driving device 3 is driven in a pattern different from the optical axis adjustment according to the inspection item, and the optical characteristics of the inspected object 900 are inspected. When the inspection is completed, the inspected product is removed (step S400), and the inspection ends.

[0045] This makes it possible to avoid convergence at local optimum points and adjust the optical axis using a global optimum point obtained in fewer steps. In the case of nonlinear regression methods such as neural networks, by performing processing that takes uncertainty into account, similar to Gaussian process regression made nonlinear using a kernel function, it is possible to avoid convergence at local optimum points and adjust the optical axis using a global optimum point obtained in fewer steps.

[0046] On the other hand, algorithms that search for an optimal point by moving multiple points, such as swarm particle optimization, are also unsuitable for inspecting optical elements. In addition, since it is unclear whether the measurement object has an optical peak close to a simple normal distribution, the stochastic gradient descent method is also unsuitable. Furthermore, since the relationship between the optical peak and the position is generally nonlinear, it is considered difficult to apply the linear regression method alone. Linear modeling and probabilistic estimation methods are also unsuitable when multiple peaks exist. In other words, by using a nonlinear modeling method and performing processing that takes uncertainty into account, convergence at a local optimal point can be avoided, and optical axis adjustment can be made using a global optimal point obtained with fewer steps.

[0047] In the optical property inspection device 1 of the present disclosure, the part performing the arithmetic processing, such as the optical axis adjustment unit 4 or the inspection control unit 8, may be configured by one piece of hardware 400 including a processor 401 and a storage device 402, as shown in FIG. 8. Although not shown, the storage device 402 includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory. Also, instead of the flash memory, an auxiliary storage device such as a hard disk may be included. The processor 401 executes a program input from the storage device 402. In this case, the program is input from the auxiliary storage device to the processor 401 via the volatile storage device. Also, the processor 401 may output data such as the calculation result to the volatile storage device of the storage device 402, or may store the data in the auxiliary storage device via the volatile storage device.

[0048] First variant. In this first modified example, an example in which an object to be inspected is driven instead of a detector will be described. Fig. 9 is a block diagram simulating the spatial arrangement of an object to be inspected and a part that detects light in order to explain the configuration of an optical property inspection device according to the first modified example. For the sake of brevity, the internal configuration of the optical axis adjustment part is not depicted in the following description, as compared to Fig. 1.

[0049] 9, the optical property inspection device 1 according to the first modified example is provided with an inspected object driving mechanism 6M that movably supports the inspected object 900, instead of a fixing jig, for the inspected object 900. A signal Scs that controls the drive of the inspected object driving mechanism 6M is output from the optical axis adjustment unit 4 to the inspected object driving mechanism 6M, and position information Ips of the inspected object 900 is output from the inspected object driving mechanism 6M to the optical axis adjustment unit 4.

[0050] In this case, the moving direction (and position) of the light source, which is the inspected object 900, is not limited to XYZ in the Cartesian coordinate system, but may be the rθφ direction in the spherical coordinate system. In this first modified example, in order to correct the incident angle of light from the inspected object 900 to the detector 2, it is preferable to use a detector having a function of correcting the incident angle, such as a bulb-tipped fiber, as the detector 2. In this first modified example, by moving the light source side, especially in the angular direction, a global optimum solution can be obtained with a smaller amount of movement.

[0051] Moreover, it is preferable that the inspected object 900 and the inspected object driving mechanism 6M have a function for fixing the inspected object 900, such as a vacuum suction mechanism, so that the emission surface of the light source, which is the inspected object 900, accurately follows the movement. Since the light source side is moved, it is also necessary to have a mechanism for connecting the inspected object 900 and the inspected object operating power supply 7, such as a probe, which moves in the same manner as the inspected object 900.

[0052] Further, in the first modified example, a mechanism for moving the detector 2 is not shown, but a mechanism for moving the detector 2 may be provided.

[0053] Second variant. In this second modified example, an example in which a lens is arranged in front of a detector will be described. Fig. 10 is a block diagram simulating the spatial arrangement of an object to be inspected and a part that detects light, in order to explain the configuration of an optical property inspection device according to the second modified example.

[0054] 10, the optical property inspection device 1 according to the second modified example has a lens 2op inserted between the exit surface of the inspected object 900 and the detector 2 in the configuration described in the first modified example. With such a configuration, the detector 2 does not necessarily need to have a function for correcting the incident angle of light.

[0055] The lens 2op may be, for example, a convex lens, a spherical convex lens, or an aspheric lens. In addition, in the second modified example, a mechanism for moving not only the detector 2 but also the inspected object 900 and the lens 2op may be provided. It is preferable to provide an appropriate moving mechanism depending on the space of the device and the emission characteristics of the light source.

[0056] Embodiment 2 In the second embodiment, instead of the single detector used in the first embodiment, a detector bundle is provided in which multiple detectors are bundled so that their incident surfaces are arranged in an arc shape. Fig. 11 is a block diagram simulating the spatial arrangement of an object to be inspected and a part that detects light, in order to explain the configuration of an optical property inspection device according to the second embodiment. Note that the operation of setting the search points is the same as in the first embodiment, and Figs. 2 to 7 described in the first embodiment are used.

[0057] The optical property inspection device 1 according to the second embodiment is provided with a detector bundle 2G in which a plurality of detectors 2 are bundled so that their incident surfaces are arranged in an arc shape, instead of the single detector 2 described in the first embodiment. The optical axis adjustment unit 4 sets a search point based on the amount of light (electrical signal SeG) detected by each detector 2 of the detector bundle 2G and the position information IpG of the detector bundle 2G output from the detector drive device 3. Then, the optical axis adjustment unit 4 controls the driving of the detector drive device 3 (outputs a drive signal ScG) based on the set search point.

[0058] The detector bundle 2G is arranged such that the incident surface is arcuate on the plane including the optical axis Ao, and the position in the emitted light direction (distance from the light source) is shifted. This eliminates the need to move it in the emitted light direction. Therefore, the detector bundle moving device 3G can be reduced by one axis compared to the detector bundle moving device 3G described in the first embodiment, and the objective variable can be reduced, which has the effect of allowing the regression calculation to converge faster.

[0059] In the figure, the incident surface of each detector 2 constituting the detector bundle 2G is configured to be convexly offset when viewed from the light source, but it may also be configured to be concave or other, and it is preferable to appropriately determine the shape depending on the characteristics of the optical semiconductor element to be measured.

[0060] Variations. The arrangement of the incident surfaces of the detectors is not limited to an arc shape as long as the distance from the light source is different. In this modified example, an example is described in which the incident surfaces of multiple detectors are arranged in a straight line so that the distance from the light source is different. Fig. 12 is a block diagram simulating the spatial arrangement of the inspected object and the part that detects light, in order to explain the configuration of the optical property inspection device according to the modified example.

[0061] The optical property inspection device 1 according to the modified example may be shifted in a straight line as shown in Fig. 12. The distance of the detector bundle 2G from the light source is not changed in an arc shape with the center of the arrangement as the apex or bottom, but is changed monotonically, for example, from one edge to the opposite edge. By adopting such a configuration, if the area of ​​the detector bundle 2G is sufficiently large, the optical axis adjustment can be completed by simply moving it in one axial direction.

[0062] Embodiment 3 In the first and second embodiments, examples of performing optical axis adjustment without preliminary measurement have been described. In the third embodiment, an example of performing optical axis adjustment after acquiring light quantity mapping information will be described. FIGS. 13 to 15 are for explaining the configuration and operation of the optical property inspection device according to the third embodiment, in which FIG. 13 is a block diagram simulating the spatial arrangement of the inspected object and the part acquiring the light quantity mapping when acquiring the light quantity mapping information, and FIG. 14 is a block diagram simulating the spatial arrangement of the inspected object and the part detecting light in a state in which the equipment is replaced after acquiring the light quantity mapping information. Also, FIG. 15 is a flow chart for explaining the operation of the optical property inspection device. Note that the setting operation of the search point is the same as in the first embodiment, and FIGS. 2 to 6 described in the first embodiment are used.

[0063] As shown in Fig. 13, the optical property inspection apparatus 1 according to the third embodiment places a camera 2C in a preliminary step with respect to the emission surface of an object to be inspected 900 fixed to an object to be inspected fixing jig 6. A CCD (Charge-Coupled Device) image sensor, a CMOS (Complementary Metal-Oxide-Semiconductor) sensor, or the like is used as the sensor of the camera 2C. The camera 2C is supported by a camera moving device 3C that is movable in at least one axial direction (the direction of the arrow in the figure) in order to adjust the position of the camera 2C in the emission light direction. This allows the camera 2C to acquire light quantity mapping information of the light emitted from the light source (step S130), as shown in Fig. 15.

[0064] Based on the mapping information obtained here, the equipment is replaced with a configuration such as that shown in Fig. 14 (step S140). At that time, in the optical axis adjustment (step S200), the movement range of the detector 2 is searched only within the range of the resolution of the camera 2C and the resolution of the stepping motor from the coordinate point where the maximum light amount on the light amount mapping is obtained. In other words, by obtaining the light amount mapping information in advance, accurate optical axis adjustment can be performed with fewer search points.

[0065] First variant. The device used to acquire the light quantity mapping information is not limited to a camera. In this first modified example, an example in which a phosphor is used instead of a camera will be described. Fig. 16 is a block diagram simulating the spatial arrangement of an object to be inspected, a part for acquiring light quantity mapping information, and a part for detecting light, of an optical property inspection device according to the first modified example.

[0066] In the optical property inspection device 1 according to the first modification, a phosphor 2L may be used instead of a camera as a configuration for acquiring light quantity mapping information, as shown in Fig. 16. A phosphor 2L corresponding to the emission wavelength of the light source is arranged at the end of the light emitted from the light source (inspection subject 900) so as to spread perpendicularly to the optical axis Ao. In addition, a detector 2 is arranged so as to penetrate the center of the phosphor 2L.

[0067] When performing the optical axis adjustment, the camera 2C captures an image of the phosphor 2L while the light source is emitting light, thereby obtaining mapping data regarding the spread of light from the light source based on the light emission state of the phosphor 2L, and simultaneously performing the optical axis adjustment. In other words, the light quantity distribution information acquisition (step S130) described in Fig. 15 is performed in parallel in step S200, and the equipment replacement (step S140) is skipped. In this case, the light emission state of the phosphor 2L is used as the objective variable, and the optical axis adjustment can be completed quickly by using a statistical method such as Gaussian process regression.

[0068] In this case, the phosphor 2L has an area that takes into consideration the spread of the emitted light from the light source, specifically, 1 × 1 cm 2 In this modification, the optical axis may be adjusted in a dark room in order to detect the light emission state of the phosphor 2L more precisely.

[0069] Second variant. Alternatively, an AD conversion board may be used to connect the photoelectric converter that converts an optical signal into an electric signal to the optical axis adjustment unit. Fig. 17 is a block diagram showing the spatial arrangement of the inspection object and the light detection unit of the optical property inspection device according to the second modified example.

[0070] In the optical property inspection device 1 according to the second modification, as shown in Fig. 17, the optical axis adjustment unit 4A is configured by a computer equipped with an AD conversion board. This electrically connects the computer and the photoelectric converter 5 via the AD conversion board. For example, by synchronizing the motor movement period with the timing of acquiring a signal from the AD conversion board, it becomes possible to continuously acquire the output of the photoelectric converter 5 that converts the optical output So at a specific position into an electrical signal Se. With this configuration, it becomes possible to acquire electrical signal data even before moving to a point where a statistically high output is obtained, and as a result, regression is performed using a large amount of data, and as a result, the regression calculation can be expected to converge quickly.

[0071] Embodiment 4 In this fourth embodiment, an example will be described in which equipment for measuring the position and angle of the object to be inspected is provided in the optical axis adjustment. Fig. 18 is a block diagram for explaining the configuration and operation of an optical property inspection device according to the fourth embodiment, simulating the spatial arrangement of a part for checking the installation state of the object to be inspected and a part for detecting light. Note that the optical axis adjustment operation is the same as in the first embodiment, and Figs. 2 to 5 and Fig. 7 described in the first embodiment, and Fig. 15 described in the third embodiment are used.

[0072] 18, the optical property inspection apparatus 1 according to the fourth embodiment has a detector 2 supported by a detector drive device 3 on the emission surface side of an optical semiconductor element (light source) which is an object under inspection 900. In this case, the detector 2 may be a single detector 2, or the detectors 2 may be bundled together to increase the effective light receiving area.

[0073] The light source, which is the object under inspection 900, is imaged using camera 6C before the optical axis is adjusted. From the image information of the light source obtained, position information of the emission end face and arrangement information such as the inclination angle of the light source are obtained using image processing technology. This corresponds to replacing the light quantity distribution information acquisition (step S130) described in FIG. 15 of the third embodiment with light source arrangement information acquisition. Also, the equipment replacement (step S140) is skipped.

[0074] The range in which the detector 2 is moved is limited based on the position information of the light source obtained by image processing. With this configuration, the optical axis adjustment can be completed more quickly. Machine learning may be performed using the position information of the light source obtained by image processing, the tilt angle, and the converged position information Ip of the detector 2 (detector driving device 3) as learning data. By using machine learning, it becomes possible to set the initial position of the detector 2 to a point closer to the optimal point, and it becomes possible to further limit the range of movement of the detector 2.

[0075] First variant. To acquire the arrangement information of the light source, a laser displacement meter or the like may be used in combination with a camera. In this first modified example, an example of acquiring the arrangement information of the light source by combining a camera and a one-dimensional laser displacement meter will be described. Fig. 19 is a block diagram simulating the spatial arrangement of an inspected object of the optical property inspection device according to the first modified example, a part for acquiring the arrangement information of the inspected object, and a part for detecting light.

[0076] In the optical property inspection device 1 according to the first modification, as a configuration for acquiring the arrangement information, a camera 6C and a one-dimensional laser displacement meter 6D are combined as shown in Fig. 19. When, for example, a plate-shaped optical semiconductor element is used as the light source, the one-dimensional laser displacement meter 6D is arranged so as to irradiate the main surface with laser light from a position separated along the normal to the main surface with respect to the light source which is the inspected object 900. With such a configuration, in addition to the position and tilt information of the light source acquired by the camera 6C, height information from the one-dimensional laser displacement meter 6D can be acquired.

[0077] In addition, by acquiring multiple points as light source height information using the one-dimensional laser displacement meter 6D, it becomes possible to acquire information on the vertical tilt of the light source. By inputting the light source height information and vertical tilt information into the prediction algorithm, it becomes possible to predict an initial position closer to the optimal point, and the optical axis adjustment can be completed more quickly. In this case, the initial position may also be optimized using machine learning or the like.

[0078] Second variant. A two-dimensional laser displacement meter may be used as the laser displacement meter. Fig. 20 is a block diagram simulating the spatial arrangement of the object to be inspected in the optical property inspection device according to the second modification, the part that acquires the position information of the object to be inspected, and the part that detects light. The optical property inspection device 1 according to the second modification is provided with a two-dimensional laser displacement meter 6D2 as shown in Fig. 20, instead of the combination of the camera 6C and the one-dimensional laser displacement meter 6D in the first modification.

[0079] With this configuration, it is possible to obtain the surface morphology of the light source, which is the object under inspection 900, and it is possible to obtain the inclination of the light source's emission surface, the inclination in the vertical direction, and the horizontal position information, i.e., the arrangement information, all at once. When determining the initial position of the detector 2 based on the information obtained by the two-dimensional laser displacement meter 6D2, it is possible to set the initial position near the point where the maximum amount of light is obtained. In addition, since the inclination information is available, it is also possible to reduce the search range. As a result, it is possible to reduce the inspection time and calculation time.

[0080] Embodiment 5. In each of the above embodiments, an example in which optical axis adjustment is performed on optical semiconductor elements as objects to be inspected one by one will be described. In this fifth embodiment, an example in which a plurality of light sources as objects to be inspected at once will be described. FIG. 21 is a block diagram illustrating the configuration and operation of an optical property inspection device according to the fifth embodiment, which illustrates the spatial arrangement of two light sources as objects to be inspected and a portion that detects light. Note that the optical axis adjustment operation is the same as in the first embodiment, and FIGS. 2 to 7 described in the first embodiment will be used.

[0081] 21, the optical property inspection apparatus 1 according to the fifth embodiment uses two optical semiconductor elements 900a and 900b as an object under inspection 900. In addition, as a detector, a detector bundle 2G in which a plurality of detectors 2 are bundled together is used. For simplicity, the number of light sources is two, but three or more may be used.

[0082] As the test subject operating power supply 7, for example, a pulse signal with a known period is applied alternately to the optical semiconductor element 900a and the optical semiconductor element 900b, and the pulse signal is used as a trigger to acquire an electrical signal SeG from the photoelectric converter 5. With this configuration, it becomes possible to distinguish and acquire the optical signals of the multiple optical semiconductor elements 900a, 900b, without moving the detector bundle 2G.

[0083] Furthermore, the destination of detector bundle 2G is determined by using Gaussian process regression by nonlinear modeling using the above-mentioned kernel function, and processing is performed taking uncertainty into consideration. For example, detector bundle 2G is first moved so that the regression calculation of one optical semiconductor element of inspected object 900 converges, and the information from the first movement is reused for the regression calculation from the second optical semiconductor element.

[0084] By using such a configuration, it is expected that the convergence time of the average regression calculation per optical semiconductor element can be shortened. In this case, it is preferable that the performance of the computer used as the optical axis adjustment unit 4, for example, the specifications of the memory and the CPU (Central Processing Unit), be appropriately selected according to the number of optical semiconductor elements. Furthermore, multiple computers may be used as necessary.

[0085] In this configuration, when an optical fiber is used as a detector, it is not necessary to use only one, and a bundle of optical fibers may be used similarly to the detector bundle 2G. In addition, when the pitch between the light sources supported by the fixture 6 for fixing the object to be inspected is within a range of, for example, the pitch distance of about ±1 mm, a detector or detector bundle corresponding to the number of light sources matching the pitch interval between the optical semiconductor elements may be provided.

[0086] In addition, the multiple optical semiconductor elements do not necessarily need to be arranged in a plane, and may be arranged three-dimensionally. As in the fourth embodiment, the object under inspection 900 may be imaged and height information obtained using the camera 6C, the one-dimensional laser displacement meter 6D, the two-dimensional laser displacement meter 6D2, etc., and the destination of the detector bundle 2G may be determined or the range of movement may be limited using the information.

[0087] Furthermore, to determine the initial position of the detector bundle 2G, the camera 2C, phosphor 2L, etc. may be used to obtain in advance information on the light intensity distribution of the light emitted from the light source, as in the second embodiment or its modified example, and the initial position may then be determined. The field of view of the camera 2C and the area of ​​the fluorescent surface of the phosphor 2L used in this case are appropriately determined according to the arrangement of the multiple light sources.

[0088] In addition, although various exemplary embodiments and examples are described in this disclosure, various features, aspects, and functions described in one or more embodiments are not limited to application of a specific embodiment, but can be applied to the embodiments alone or in various combinations. Therefore, countless modifications not exemplified are expected within the scope of the technology disclosed in this specification. For example, the following are included: modifying, adding, or omitting at least one component; and extracting at least one component and combining it with a component of another embodiment.

[0089] As described above, the optical property inspection apparatus 1 of the present disclosure includes the detector 2 that receives the light emitted from the optical semiconductor element (object under inspection 900), a driving device (detector driving device 6, detector bundle moving device 6G, camera moving device 3C, object under inspection driving mechanism 6M) that positions and drives the measurement position of either the optical semiconductor element (object under inspection 900) or the detector 2, and an optical axis adjustment unit 4 that controls driving of the driving device and performs a search calculation for a position at which the maximum amount of light is obtained from the optical semiconductor element (object under inspection 900) among the measurement positions based on position information Ip indicating the measurement position obtained from the driving device and light amount information (electrical signal Se) output from the detector 2 each time positioning is performed, and adjusts the optical axis of the optical semiconductor element (object under inspection 900). The optical axis adjustment unit 4 performs the search calculation using a regression method by nonlinear modeling (for example, linear process regression performed by nonlinear modeling using a kernel function, or a neural network) taking into account the amount of positional deviation caused by the driving device. This suppresses the effects of noise, and even if a peak split occurs, convergence at a local optimum point is avoided, making it possible to adjust the optical axis using a global optimum point obtained in fewer steps.

[0090] In this case, if the optical axis adjustment unit 4 is provided with a convergence determination unit 43 that determines the convergence state of the search calculation, and a re-search position setting unit 44 that sets a re-search position when the convergence determination unit 43 determines that convergence has occurred to a certain extent, the effect of noise can be further reduced.

[0091] Furthermore, if the re-search position setting unit 44 sets the re-search position from among a plurality of positions that may show the maximum light amount by weighting using variance or by allocating using random numbers, the effect of noise can be reduced more reliably.

[0092] If an angle correcting lens 2op is disposed between the optical semiconductor element (object under test 900) and the detector 2, correction of the angle of incidence becomes unnecessary.

[0093] If a detector bundle 2G is provided in which detectors at different distances from the emission surface of the optical semiconductor element (test object 900) are bundled together, the objective variable can be reduced by omitting movement in the bundled direction (overlapping detectors 2), thereby enabling faster regression calculations.

[0094] If a camera 2C is provided that captures the light intensity distribution of the emitted light, and the optical axis adjustment unit 4 narrows down the range in the search calculation based on the light intensity distribution information of the emitted light obtained from the camera 2C, the number of calculations can be reduced and the regression calculation can be performed faster.

[0095] Alternatively, a phosphor 2L that receives the emitted light and a camera 2C that captures the light emission state of the phosphor 2L may be provided, and the optical axis adjustment unit 4 may narrow down the range in the search calculation based on the light emission distribution information of the phosphor 2L obtained from the camera 2C, thereby reducing the number of calculations and enabling faster regression calculations.

[0096] By providing an element camera (camera 6C) for photographing the optical semiconductor element (object under test 900), and the optical axis adjustment unit 4 setting the initial position in the search calculation based on information indicating the position of the optical semiconductor element (object under test 900) obtained from the element camera (camera 6C), the number of calculations can be reduced and regression calculations can be performed quickly.

[0097] The optical axis adjustment unit 4 is equipped with laser displacement meters (one-dimensional laser displacement meter 6D, two-dimensional laser displacement meter 6D2) that measure the position of the optical semiconductor element (object under test 900), and even if the initial position in the search calculation is set based on information indicating the position of the optical semiconductor element (object under test 900) obtained from the laser displacement meters, the number of calculations can be reduced and regression calculations can be performed quickly.

[0098] The object under test 900 is provided with an object under test operating power supply 7 which operates a plurality of optical semiconductor elements 900a, 900b individually, and the optical axis adjustment unit 4 controls the object under test operating power supply 7 so that the plurality of optical semiconductor elements 900a, 900b emit light at mutually different timings. By using the result of a search calculation for one of the plurality of optical semiconductor elements 900a, 900b for the search calculation for the other element, the number of calculations can be reduced and regression calculations can be performed at high speed. [Explanation of symbols]

[0099] 1: optical property inspection device, 2: detector, 2C: camera, 2G: detector bundle, 2L: phosphor, 2op: lens, 3: detector drive device, 3C: camera movement device, 3G: detector bundle movement device, 4: optical axis adjustment unit, 41: optimum position search unit, 42: variable processing unit, 43: convergence judgment unit, 44: re-search position setting unit, 5: photoelectric converter, 6: inspected object fixing jig, 6C: camera (camera for element), 6D: one-dimensional laser displacement meter (laser displacement meter), 6D2: two-dimensional laser displacement meter (laser displacement meter), 6M: inspected object drive mechanism, 7: inspected object operating power supply, 8: inspection control unit, 900: inspected object (optical semiconductor element), Ip: position information, Scd: drive signal, Se: electrical signal.

Claims

1. A detector that receives light emitted from an optical semiconductor device. A drive device for positioning and driving the measurement position of either the optical semiconductor element or the detector, and The system includes an optical axis adjustment unit that controls the drive of the drive unit and, each time positioning is performed, calculates the search for the position among the measurement positions from which the maximum light intensity can be obtained from the optical semiconductor element based on the position information indicating the measurement position obtained from the drive unit and the light intensity information output from the detector, and adjusts the optical axis of the optical semiconductor element. The optical axis adjustment unit performs the search calculation using a regression method based on nonlinear modeling, taking into account the amount of positional displacement caused by the drive device. The optical axis adjustment unit includes: An optical properties inspection apparatus characterized by comprising a convergence determination unit for determining the convergence state of the search calculation, and a re-search position setting unit that, when the convergence determination unit determines that it has converged to a certain extent, sets a re-search position from among a plurality of positions that may show the maximum light intensity by weighting by variance or distribution by random numbers.

2. The optical properties inspection apparatus according to claim 1, characterized in that an angle correction lens is arranged between the optical semiconductor element and the detector.

3. The optical property inspection apparatus according to claim 1, characterized in that the detector comprises a detector bundle in which detectors at different distances from the emission surface of the optical semiconductor element are bundled together.

4. The system includes a camera that captures the light intensity distribution of the emitted light, The optical characteristic inspection apparatus according to claim 1, characterized in that the optical axis adjustment unit narrows down the range in the search calculation based on the light intensity distribution information of the emitted light acquired from the camera.

5. A phosphor that receives the emitted light, and The system includes a camera for capturing images of the light emission state of the phosphor. The optical property inspection apparatus according to claim 1, characterized in that the optical axis adjustment unit narrows down the range in the search calculation based on the emission distribution information of the phosphor acquired from the camera.

6. The device is equipped with a camera for photographing the aforementioned optical semiconductor device, The optical characteristic inspection apparatus according to claim 1, characterized in that the optical axis adjustment unit sets the initial position in the search calculation based on information indicating the position of the optical semiconductor element obtained from the element camera.

7. The system includes a laser displacement meter for measuring the position of the aforementioned optical semiconductor element, The optical property inspection apparatus according to claim 1, characterized in that the optical axis adjustment unit sets the initial position in the search calculation based on information indicating the position of the optical semiconductor element obtained from the laser displacement meter.

8. The device under test is equipped with a power supply for operating each of the multiple optical semiconductor elements individually. The optical axis adjustment unit controls the power supply for the object under inspection so that it emits light from a plurality of optical semiconductor elements at different timings, and uses the result of the search calculation for one of the plurality of optical semiconductor elements for the search calculation for the other elements, as described in any one of claims 1 to 7.

Images