Optical coupling module for testing an element to be tested, test unit, method for operating an optical coupling module, method for producing an optical coupling module and control unit

Abstract

The approach presented here creates an optical coupling module (105) for testing an element (135) to be tested, wherein the optical coupling module (105) comprises a module carrier (107) with a test signal section (110) for outputting an optical test signal (125) to a coupling region (130) of the element (135) to be tested or for receiving an optical test signal (125) from the coupling region (130) of the element (135) to be tested, and a camera system (140) fixed to the module carrier (107) for detecting the position of the coupling region (130) of the element (135) to be tested in relation to the module carrier (107).

Description

[0001] The approach presented here creates an optical coupling module for testing an element under test, a test unit, a method for operating an optical coupling module, a method for manufacturing an optical coupling module, and a control unit according to the main claims. Such a module and method are generically known from US 2011 / 0 279 812 A1 and WO 2019 / 029 765 A1.

[0002] WO2021 / 078318 A1 discloses a wafer-level test method for testing optoelectronic chips arranged on a wafer, with electrical interfaces in the form of contact pads and fixed optical interfaces in the form of optical deflection elements. In three adjustment steps, the wafer with one of the chips is aligned to a contacting module such that the electrical interfaces of the chip and the contacting module are in contact with each other and the optical interfaces of the chip and the contacting module (2) assume a maximum position for optical coupling. The method is relatively complex.

[0003] US 2006 / 0 109 015 A1 describes an optoelectronic probe module for testing chips (devices under test - DUTs) with electrical and optical inputs and outputs. If, as described in US 2006 / 0 109 015 A1, the coupling efficiency of the optical signal is optimized by collimating or focusing the optical beam, the entire probe module must be adjusted with high precision in the sub-µm range, which is very complex.

[0004] US 2011 / 0 279 812 A1 discloses a contacting module for testing chips with electrical and optical inputs and outputs. The chip is mounted on a movable carrier, which allows it to be roughly aligned with the contacting module. Rough alignment is performed sensor-controlled based on a position monitor of the chip or the chip's alignment marks. This is complicated and prone to failure.

[0005] US Pat. No. 7,412,138 B1 discloses optoelectronic alignment structures for wafer-level testing of optical and optoelectronic chips. The wafer-level test system uses optical and electronic probes to locate and align an optoelectronic alignment structure and includes adjustment for maximum performance. The alignment process and the alignment structures are relatively complex.

[0006] For example, to test photonic integrated circuits in volume production, special units or test solutions are used, for example in the form of an optoelectronic probe card. A key feature here should be plug-and-play capability with existing wafer-level test equipment and wafer probers, which are used in volume production of conventional ICs. To enable this, the insufficient positioning accuracies of conventional wafer probers (currently ±1.5 µm) for reproducible optical coupling should be compensated for by a suitable, position-tolerance-insensitive, optical coupling principle. The required positioning accuracy is in the 1 µm or even sub-µm range. The exact value depends heavily on the coupling structure used on the PIC (grating) and the illumination / detection optics.Currently, UFO Probe technology can only measure PICs (PIC = photinic integrated coupler), in which the light is coupled to a surface via grating couplers (GCs). However, the currently used technology is difficult to use with evanescent couplers.

[0007] Because active alignment requires optimizing the position of a fiber array (or individual fiber), such position adaptation is relatively slow and therefore unsuitable for high-volume testing. Furthermore, the tracking system requires a large footprint, making this approach less suitable for use in a fully automated test environment (ATE). Another disadvantage of a typical test unit setup is that crosstalk makes coupling and decoupling very inefficient. Typical losses are in the range of several dB.

[0008] Against this background, an optical coupling module for testing an element to be tested is proposed, wherein the optical coupling module has the following features: - a module carrier with a test signal section for outputting an optical test signal to a coupling area of ​​the element to be tested or for receiving an optical test signal from the coupling area of ​​the element to be tested; and - a camera system fixed to the module carrier for detecting the position of the coupling area of ​​the element to be tested in relation to the module carrier.

[0009] A module carrier can be understood, for example, as a monolithic assembly in which light beams can be guided as test signals. For this purpose, the module carrier can, for example, have one or more waveguides or be designed to be transparent. A test signal section can be understood as the area of ​​the module carrier via which an optical test signal is coupled out of the module carrier and, for example, emitted to a coupling area of ​​the element to be tested in order to be coupled into the element to be tested there, or via which an optical test signal can be coupled into the module carrier and subsequently evaluated in a corresponding evaluation unit. A camera system in this case can be understood as an assembly with at least one image sensor which is designed and aligned to specifically detect a position of the coupling area of ​​the element to be tested.The camera system is firmly fixed to the module carrier or embedded on or in the module carrier.

[0010] The approach presented here is based on the realization that very precise positioning of the optical coupling module can be achieved by evaluating a signal from the camera system, which is fixed to the module carrier, very precisely and with minimal installation space requirements. For example, if the position of the optical coupling module is misaligned, the position of the module carrier in relation to the element to be tested can be quickly and easily adjusted. By fixing the camera system directly to the module carrier, it is also possible to avoid misalignments of the position of the optical coupling module in relation to the element to be tested due to tolerances or signs of wear in the system, which could lead, for example, to an insufficient power of an optical test signal being directed into or onto the coupling area.

[0011] A particularly advantageous embodiment of the approach proposed here is one in which the camera system comprises at least one image sensor and one imaging optical element, in particular wherein the image sensor and the imaging optical element are arranged on different and / or opposite sides of the module carrier. Such an embodiment offers the advantage of being able to achieve very precise focusing of the coupling region on the image sensor through the use of the image sensor in combination with the imaging optical element. At the same time, such an embodiment can have a very small installation space requirement.

[0012] Specifically, according to one embodiment of the approach proposed here, the imaging optical element can be designed as a microlens array or as a diffractive imaging system, in particular comprising at least one Fresnel lens or a metastructure. Such an embodiment offers the advantage of being able to form the imaging optical element particularly easily on or in the module carrier, whereby such an imaging optical element very efficiently enables corresponding observation of the position of the coupling region of the element to be tested.

[0013] The camera system can be fixed to the module carrier particularly securely if, according to one embodiment, the camera system is monolithically connected to and / or with the module carrier.

[0014] Another conceivable embodiment of the approach proposed here is one in which the camera system further comprises an illumination unit for illuminating the coupling region of the element to be tested, in particular wherein the illumination unit is arranged on the same side as an image sensor of the camera system or adjacent to the image sensor of the camera system. Such an embodiment offers the advantage of being able to clearly and precisely detect the position of the coupling region of the element to be tested, even independently of the output of an optical test signal. Specifically, for example, the illumination unit can also be designed to emit light with a different wavelength, shape, intensity, and / or duration than the optical test signal, so that indifference or interference in the light emitted by the illumination unit does not lead to a change in the optical test signal or an optical test signal.

[0015] A particularly advantageous embodiment is proposed in which the camera system is designed to detect the distance of the coupling region of the element to be tested from the module carrier. In this way, the positioning of the element to be tested in a z-direction, i.e., a height relative to the optical coupling module, can also be detected, so that, for example, an initial alignment of the element to be tested in an x- and / or y-direction is enabled, after which an adjustment of the height or an alignment of the element to be tested in a z-direction is carried out. In this way, for example, electrical contact elements such as contact needles can be protected if it can be avoided that an alignment of the element to be tested in an x- and / or y-direction occurs after a conversion has taken place.

[0016] The position of the coupling area of ​​the element to be tested can be determined very clearly if, according to one embodiment, the camera system is arranged on a boom of the module carrier and / or where an optical path of the optical test signal and a viewing direction of the camera system intersect, or where the optical path of the optical test signal and the viewing direction of the camera system are skewed to each other. By arranging the camera system on a boom of the module carrier, for example, it can be achieved that the camera system has the clearest possible viewing direction of the coupling area of ​​the element to be tested.In an arrangement of the camera system in which the optical path of the optical test signal crosses a viewing direction of the camera system or in which the optical path of the optical test signal and the viewing direction of the camera system are skewed to each other, a very compact optical coupling module can be realized in which the corresponding light path is guided through an interior of the module carrier, so that the module carrier has a very small installation space requirement overall.

[0017] A particularly advantageous embodiment of the approach proposed here is one in which the module carrier has an imaging optics system for outputting the optical test signal to or into the coupling region of the element to be tested, in particular wherein the imaging optics system has a curved mirror or a light deflection element for changing the beam direction of the optical test signal before it impinges on the coupling region of the element to be tested. Such an embodiment offers the advantage of enabling a high degree of flexibility in the design of the external shape and / or the installation space requirements of the module carrier through the design of the imaging optics system.

[0018] According to a further embodiment, a test unit for optical testing of a test element is presented, wherein the test unit has the following features: - a variant of an optical coupling module presented here; and - an evaluation unit designed to send an optical test signal through the optical coupling module to the element to be tested and to evaluate a test signal or evaluation signal received from the element to be tested.

[0019] Even with such an embodiment, the advantages mentioned above can be implemented in a technically simple, cost-effective and efficient manner.

[0020] A particularly precise measurement is achieved by an embodiment of the approach proposed here, in which a motion unit is provided to move the element to be tested in response to a signal from the camera system. Such an embodiment offers the advantage, for example, of correctly positioning the element to be tested prior to testing, in order to enable the best possible conversion or irradiation of the optical test signal into appropriately designed areas of the element to be tested.

[0021] Another very robust embodiment of the approach proposed here is one in which the test unit has at least one electrical contacting unit for contacting at least one electrical contact area of ​​the element to be tested. In particular, the contacting unit is designed to contact the electrical contact area of ​​the element to be tested after a movement of the element to be tested that occurred in response to a signal from the camera system. Such an embodiment offers the advantage of being able to reliably test additional functions of the element to be tested, and in particular, mechanical damage to the contacting unit can be largely avoided.

[0022] The above-mentioned advantages can also be realized in a further embodiment of the approach proposed here as a method for operating a variant of an optical coupling module presented here, the method comprising the following steps: - Evaluating the position of the element to be tested in relation to the module carrier using the camera system, and - Output of the optical test signal to or into the coupling area of ​​the element to be tested.

[0023] Also, according to another embodiment, a method for producing an optical coupling module according to a variant presented here can be realized, wherein the method comprises the following steps: - Providing the module carrier; and - Forming or attaching the camera system to or in the module carrier to produce the optical coupling module.

[0024] These methods can be implemented, for example, in software or hardware or in a mixture of software and hardware, for example in a control unit.

[0025] The approach presented here further provides a control unit configured to perform, control, or implement the steps of a variant of a method presented here in corresponding devices. This embodiment of the invention in the form of a control unit also allows the problem underlying the invention to be solved quickly and efficiently.

[0026] For this purpose, the control unit can have at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or an actuator for reading sensor signals from the sensor or for outputting data or control signals to the actuator, and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The computing unit can be, for example, a signal processor, a microcontroller, or the like, wherein the memory unit can be a flash memory or a magnetic storage unit.The communication interface can be designed to read in or output data wirelessly and / or wired, wherein a communication interface that can read in or output wired data can read this data, for example, electrically or optically from a corresponding data transmission line or output it to a corresponding data transmission line.

[0027] In this case, a control unit can be understood as an electrical device that processes sensor signals and outputs control and / or data signals depending on them. The control unit can have an interface that can be implemented in hardware and / or software. In a hardware implementation, the interfaces can, for example, be part of a so-called system ASIC, which contains a wide variety of functions of the control unit. However, it is also possible for the interfaces to be separate integrated circuits or to consist at least partially of discrete components. In a software implementation, the interfaces can be software modules that are present, for example, on a microcontroller alongside other software modules.

[0028] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out, implement and / or control the steps of the method according to one of the embodiments described above, in particular when the program product or program is executed on a computer, a control unit or generally a device.

[0029] Examples of the approach presented here are shown in the drawings and explained in more detail in the following description. It shows: Fig. 1 a schematic representation of an embodiment of a test unit with an embodiment of an optical coupling module; Fig. 2 a schematic representation of a further embodiment of a test unit with another embodiment of an optical coupling module; Fig. 3 a flowchart of an embodiment of a method for operating a variant of an optical coupling module presented here; Fig. 4 a flow diagram of an embodiment of a method for producing a variant of an optical coupling module presented here; Fig. 5 a block diagram of a control unit for executing a variant of the method for operating a variant of an optical coupling module presented here; and Fig. 6 a block diagram of a control unit for carrying out the method for producing a variant of an optical coupling module presented here.

[0030] In the following description of advantageous embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, whereby a repeated description of these elements is omitted.

[0031] Fig. 1 shows a schematic representation of an embodiment of a test unit 100 with an embodiment of an optical coupling module 105. The optical coupling module 105 comprises an imaging optics 110 on a module carrier 107, which is designed to generate an optical test signal 115, which is transmitted, for example, from an evaluation unit 120 via a waveguide 125 in the module carrier 105 to a coupling region 130 of an element under test 135 (DuT = device under test). This optical test signal 115 can be used, for example, to test the functionality of the element under test 135, which, for example, forms an optical component.The coupling region 130 can, for example, be designed as a grating coupler, so that very precise positioning of the optical coupling module 105 is required for coupling the optical test signal 115 into the coupling region 130, since otherwise the optical test signal 115 cannot be efficiently coupled into the coupling region 130. To ensure such precise positioning, the optical coupling module 105 has a camera system 140, which is arranged on a boom 145 of the optical coupling module 105. This boom 145 is provided as a projection above the imaging optics 110 and comprises, on an underside facing the coupling region 130, an imaging optics element 150 and, on the upper side opposite the imaging optics element 150, an image sensor 155, which can also be referred to as a camera chip.Furthermore, an illumination unit 160 is arranged next to or adjacent to the image sensor 155, which is designed to radiate an illuminating light through the (preferably transparent) cantilever 155 onto the coupled region 130. The imaging optical element 150 and the image sensor 155 can thus detect the position of the coupling region 130 in a corresponding beam path 165, wherein this detected position is then also fed, for example, to the evaluation unit 120 in a corresponding signal 170. In the evaluation unit 120, a movement unit 175 can then be controlled, for example, in accordance with the signal 170, in order to move the element 135 to be tested, which is formed, for example, as an optical integrated circuit on a wafer, in corresponding directions 177, so that precise irradiation of the optical test signal 125 into the coupled region 130 is possible.At the same time, it can also be ensured that the position of the element 135 to be tested is carried out at a corresponding depth below the optical coupling module 105 in order to avoid, for example, contact units 180, which are designed, for example, as contact needles of a test head 182, already being contacted with corresponding contact areas 185 during repositioning, so that a corresponding movement of the element 130 to be tested could potentially bend or otherwise damage these contact units 180. Once the element 135 to be tested is correctly adjusted, the distance between the optical coupling module 105 and the element 135 to be tested can be reduced, for example, so that the contact units 180 are electrically contacted with the corresponding contact areas 185.In this case, for example, the optical test signal 135 can be output to the coupled area 130, and a corresponding test signal 187 can be read in again via the coupled area 130, which can then be evaluated in the evaluation unit 120. This can then be used, for example, to test the correct functionality of the element 135 to be tested.

[0032] Fig. 2 shows a schematic representation of a further embodiment of a test unit 100 with another embodiment of an optical coupling module 105. In contrast to the Fig. In the embodiment shown in Figure 1, the camera system 140 is not arranged on a boom, but directly on the module carrier 105, so that a beam path of the optical test signal 125 and the beam path 165 intersect or are arranged skewed relative to each other. However, such an embodiment offers the advantage of a very compact component for the optical coupling module 105, since the module carrier 107 does not need to include a boom 145.

[0033] In the approach presented here, the prober technology is to be supplemented by an additional imaging system such as the camera system 140, with which the position of the gratings or the coupling region 130 relative to the optical coupling module 105 can be detected and quickly adjusted. This eliminates the need for a complex optimization process (similar to that described in active alignment). At the same time, no bulky structure is necessary, because the camera system 140 can be integrated directly into the optical coupling module 105 of the UFO Probe Card (OLGA) or the test unit 100 and then, via a feedback loop, readjust either the DuT or the element 135 to be tested (via the prober) or the optical coupling module 105 itself for each DuT 135 in one step. This method allows the testing of the element 135 to be tested to use illumination patterns adapted to the grating modes as test signals 125, so that overexposure is no longer necessary (orThis reduces the distance to a minimum). This allows the efficiency of the UFO probe technology to be increased by orders of magnitude. Because the imaging system or the camera system 140 and the coupling module 105 are advantageously connected monolithically (the camera system 140 is integrated in the coupling module 105, for example), very precise positioning can be achieved. Since the positional tolerances of the grating couplers as the coupling area 130 on a DuT 135 are typically very small, imaging only one (and optimizing for one) grating coupler is a particularly suitable design.

[0034] The adjustment of the probe is particularly suitable for readjustment, as it simplifies the setup of the probe card with the optical coupling module 105. Furthermore, a high-voltage supply for a piezo element, which can interfere with the electronic measurement process, is not required. Alternatively, the optical chip itself can also be readjusted, for example, via a piezo element.

[0035] Ideally, adjustments should be made in free-flying probe mode (i.e., before contacting, for example, the contact units 180) to avoid damage to the needles required for electronic contacting. For this purpose, the image plane of the imaging optical element 165 should ideally be located in the area of ​​the lowered wafer on or in which the element 135 to be tested is arranged.

[0036] The specific imaging system or camera system 140 should, for example, consist of a micro-optic system or an imaging optical element 150 and a miniaturized camera chip 155. For the camera 155, for example, a relatively small chip is required, the external dimensions of which should not exceed the dimensions of the optical coupling module 105. However, a relatively low resolution (240 x 320 pixels or less) is sufficient. The imaging of the DuT plane or the coupling region 130 onto the camera chip 155 can, for example, be achieved via a micro-optical imaging system 150. Either a microlens array or a diffractive imaging system (Fresnel lens or metastructure) can be used as the imaging optical element 150. The latter can be applied directly to the OLGA or the module carrier 107 using various methods (lithographic or laser-selective etching).Finally, for example, an illumination unit 160 can be provided near the camera system 140. An LED or OLED, for example, can be used for this purpose. The light from the illumination unit 160 can be imaged onto the grating or coupling region 130 using the same optics or the same imaging optics element 150 that also serves for image acquisition by the image sensor 155. A particularly suitable design of the illumination unit 160 is an LED that emits visible light, as this avoids unwanted coupling into the DuT or the element 135 under test, and allows the use of a cost-effective Si-based camera chip 155. The captured image can be evaluated using a suitable chip or the evaluation unit 120 and suitable software. Modern AI-based image recognition methods can be used for this purpose.

[0037] With reference to the above-described Fig. 1 and Fig. 2, two possible embodiments for implementing the camera system 140 on or in the module carrier 107 are presented. Both versions are approximately equivalent. In the version according to 0 of the Fig. 1, the camera system 140 is placed directly above the grating coupler or coupling area 130. For this purpose, the optical chip or image sensor 155 is supplemented by a cantilever 145 on its front side of the module carrier 107. This facilitates the design of the imaging optical element 150. The disadvantage of this design is the larger required installation space and the resulting larger minimum distance between the grating couplers or coupling area 130 and the contact areas 185 or the bond pads on the DuT or the element to be tested 135. The second design according to the illustration from Fig. 2 does not increase the space requirement of the optical chip or the optical coupling module 105 (or only insignificantly) because the imaging optical element 150 and the camera or the image sensor 155 are integrated into the existing optical coupling module 105 or are mounted there. The disadvantage of this design is, on the one hand, the complex design of the imaging optical element (a very high imaging angle should be served), and on the other hand, this design blocks the two-dimensional distribution of the optical coupling points across the coupling module 105. In addition, imaging here occurs through an area in the OLGA or the beam path 115 in which waveguides can be located, for example, for guiding the optical test signal 125. However, since these structures are relatively small, interference with the image by these waveguides is unlikely.

[0038] The illumination beam path 165 and the cable routing of the camera system 140 and the LED or the illumination unit 160 are not shown in the figures for reasons of clarity. Fig. 1 and Fig. 2. However, a particularly suitable embodiment is to route the cables along the fiber direction of the optical coupling module 105.

[0039] The depth of field of the imaging system or camera system 140 should be designed such that the positional tolerances of the probe chuck in the Z direction do not influence the image, but that the height of the wafer can be determined simultaneously in order to minimize the error in determining the position of the grating coupler or coupling region 130. This also has the advantage that the proposed system can also be used for precisely adjusting the height of the DuT 135 relative to the probe card or module carrier 107 or the optical coupling module 105, thus simplifying the contacting of the electrical pads or contact regions 185.

[0040] The approach presented here is particularly advantageous due to the integration of a second imaging system 140, so that an active feedback loop can be realized and the position tolerance can be actively compensated directly, i.e., without a slow optimization algorithm. In particular, the DuT or the element to be tested 135 does not need to be contacted and read out to optimize the coupled-in light. At the same time, the illumination system of the gratings or the output of the optical test signal 125 can be adjusted so that the illumination mode matches the mode of the grating coupler 130 well, thus enabling efficient coupling and decoupling. A further advantage of the invention is that the height of the DuT relative to the probe card or the optical coupling module 105 can be measured by the imaging system or camera system 140, and thus the typical overdrive of the prober or the coupling module 105 can be adjusted more precisely than conventional methods.

[0041] Fig. 3 shows a flow diagram of an embodiment of a method 300 for operating a variant of an optical coupling module presented here, wherein the method 300 comprises a step 310 of evaluating a position of the element to be tested with respect to the module carrier using the camera system and a step 320 of outputting the optical test signal to or into the coupling region of the element to be tested.

[0042] Fig. 4 shows a flow diagram of an embodiment of a method 400 for producing a variant of an optical coupling module presented here, wherein the method 400 comprises a step 410 of providing the module carrier and a step 420 of forming or attaching the camera system on or in the module carrier in order to produce the optical coupling module.

[0043] Fig. 5 shows a block diagram of a control unit 500 for executing a variant of the method 300 for operating a variant of an optical coupling module presented here, wherein the control unit 500 comprises a unit 510 for evaluating a position of the element to be tested with respect to the module carrier using the camera system and a unit 520 for outputting the optical test signal to or into the coupling region of the element to be tested.

[0044] Fig. 6 shows a block diagram of a control unit 600 for carrying out the method 400 for producing a variant of an optical coupling module presented here, wherein the control unit 600 has a unit 610 for providing the module carrier and a unit 620 for forming or fastening the camera system on or in the module carrier in order to produce the optical coupling module.

Claims

[1] Optical coupling module (105) for testing an element to be tested (135), the optical coupling module (105) having the following features: - a module carrier (107) with a test signal section (110) for outputting an optical test signal (125) to a coupling region (130) of the element to be tested (135) or for receiving an optical test signal (125) from the coupling region (130) of the element to be tested (135); and - a camera system (140) fixed to the module carrier (107) for detecting the position of the coupling region (130) of the element (135) to be tested in relation to the module carrier (107). [2] Optical coupling module (105) according to claim 1, wherein the camera system (140) has at least one image sensor (155) and one imaging optical element (150), in particular wherein the image sensor (155) and the imaging optical element (150) are arranged on different and / or opposite sides of the module carrier (107). [3] Optical coupling module (105) according to claim 2, wherein the imaging optical element (150) is designed as a microlens array or as a diffractive imaging system, in particular having at least one Fresnel lens or a metastructure. [4] Optical coupling module (105) according to one of the preceding claims, wherein the camera system (140) is monolithically connected to and / or with the module carrier (107). [5] Optical coupling module (105) according to one of the preceding claims, wherein the camera system (140) further comprises an illumination unit (160) for illuminating the coupling region (130) of the element to be tested (135), in particular wherein the illumination unit (160) is arranged on the same side as an image sensor (155) of the camera system (140) or adjacent to the image sensor (155) of the camera system (140). [6] Optical coupling module (105) according to one of the preceding claims, wherein the camera system (140) is designed to detect a distance of the coupling region (130) of the element to be tested (135) from the module carrier (107). [7] Optical coupling module (105) according to one of the preceding claims, in which the camera system (140) is arranged on a boom (145) of the module carrier (107) and / or in which an optical path of the optical test signal (125) and a viewing direction of the camera system (140) intersect or in which the optical path of the optical test signal (125) and the viewing direction of the camera system (140) are aligned skew to one another. [8] Optical coupling module (105) according to one of the preceding claims, wherein the module carrier (107) has an imaging optics (110) for outputting the optical test signal (125) to the coupling region (130) of the element to be tested (135), in particular wherein the imaging optics (110) has a curved mirror or a light deflection element for changing a beam direction of the optical test signal (125) before it impinges on the coupling region (130) of the element to be tested (135). [9] Test unit (100) for optically testing a test element (135), the test unit (100) having the following features: - an optical coupling module (105) according to one of the preceding claims; and - an evaluation unit (120) which is designed to send an optical test signal (125) through the optical coupling module (105) to the element to be tested (135) and to evaluate a test signal or evaluation signal (187) received from the element to be tested (135). [10] Test unit (100) according to claim 9, comprising a movement unit (175) for moving the element to be tested (135) in response to a signal from the camera system (140). [11] Test unit (100) according to one of the preceding claims 9 or 10 with at least one electrical contacting unit (185) for contacting at least one electrical contact area (185) of the element (135) to be tested, in particular wherein the contacting unit (180) is designed to make contact with the electrical contact area (185) of the element (135) to be tested after a movement of the element (135) to be tested which has occurred in response to a signal (170) of the camera system (140). [12] Method (300) for operating an optical coupling module (105) according to one of claims 1 to 8, wherein the method (300) comprises the following steps: - evaluating (310) a position of the element to be tested (135) with respect to the module carrier (107) using the camera system (140), and - Outputting (320) the optical test signal (125) to or into the coupling area (130) of the element to be tested (135). [13] Method (400) for manufacturing an optical coupling module (105) according to one of claims 1 to 8, wherein the method (400) comprises the following steps: - providing (410) the module carrier (107); and - forming (420) or attaching the camera system (140) to or in the module carrier (107) in order to produce the optical coupling module (105). [14] Control unit (500, 600) which is arranged to carry out and / or control the steps (310, 320; 410, 420) of one of the methods (300; 400) according to one of the preceding claims 12 or 13 or 13 in corresponding units (510, 520; 610, 620). [15] Computer program which is configured to execute and / or control the steps (310, 320; 410, 420) of one of the methods (300; 400) according to one of the preceding claims 12 or 13 or 13.

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