Test system with test cavity capable of being vacuumized

Abstract

The invention relates to a test system (1) having a test chamber (2) in which an object to be tested can be arranged, the test chamber (2) having at least one chamber wall (3) which delimits the test chamber (2), the test chamber (2) being provided with a first vacuum generator (12) in order to be able to generate a vacuum in the test chamber (2), and the chamber wall (3) having an opening (4), according to the invention, the chamber wall (3) is provided with an opening (4) which is provided with a sensor module (5), the sensor module (5) having a carrier element (6) which is arranged on the chamber wall (3) in such a way as to close the opening (4), and a sensor (10), in particular an optical sensor, temperature sensor, pressure sensor, gas sensor or camera sensor, which is arranged on the side of the carrier element (6) facing the test chamber (2). According to the invention, a negative pressure chamber (17) associated with the opening (4) is formed on the side of the chamber wall (3) facing away from the test chamber (2), and the negative pressure chamber (17) is associated with a negative pressure generator (19) in order to be able to generate a negative pressure in the negative pressure chamber (17) independently of a vacuum in the test chamber (2).

Description

[0001] This application claims the benefit of German patent application No. DE 10 2023 200 859.9, filed on February 2, 2023, the contents of which are hereby incorporated by reference in their entirety into this application.

[0002] The present invention relates to a test system, in particular an optical test system, comprising a test chamber in which a test object can be arranged, wherein the test chamber has at least one chamber wall which delimits the test chamber, wherein the test chamber is provided with a first vacuum generator in order to be able to generate a vacuum in the test chamber, and wherein the chamber wall has at least one opening which is provided with at least one sensor module, wherein the sensor module comprises a support element and a sensor, in particular an optical sensor, a temperature sensor, a pressure sensor, a gas sensor or a camera sensor, wherein the support element is arranged on the chamber wall in such a way as to close the opening, and wherein the sensor is arranged on a side of the support element which faces the test chamber.

[0003] Furthermore, the invention relates to a method for operating the above-mentioned test system.

[0004] Optical test systems of the type mentioned above are known in the prior art.

[0005] To test delicate and particularly delicate optical objects, such as lenses, mirrors, and the like, it is known to inspect them in clean rooms. For this purpose, a test chamber is provided in which the object to be tested can be placed. A vacuum generator is then used to evacuate the test chamber, thereby removing interfering substances from the chamber. Simultaneously, a negative pressure is generated in the chamber, meaning a pressure level lower than the ambient pressure of the chamber. Conventional sensors, particularly camera sensors, are not designed for use in a vacuum. In particular, conventional camera sensors present the problem that the electronic components required for proper functioning of the camera sensor can "outgas" in a vacuum. "Outgassing" here refers specifically to contaminants escaping from the material of the sensor's electrical / electronic components and potentially causing contamination in the test chamber and, therefore, distorting the test results. Therefore, care is usually taken to avoid placing the electronic components of such sensors themselves in the vacuum of the test chamber.

[0006] To avoid this problem, it's common to separate the sensor from the rest of the sensor module's electronics and place only the sensor inside the test chamber, while the rest of the electronics are located outside. This significantly reduces outgassing issues. However, this approach comes with the caveat that the often sensitive or fragile sensor signals that must be transmitted from the sensor to the electronics are routed through vacuum feedthroughs, which can lead to other issues. These feedthroughs are particularly challenging and often costly to implement, especially for high-speed recording or signal processing. Signal integrity is also often compromised by vacuum feedthroughs.

[0007] An alternative approach is to use the sensor itself as the separation point between the test chamber and the external environment, so that only the portion of the sensor module that actually needs to be in vacuum—the sensor itself—is exposed to the negative vacuum pressure. This improves the outgassing problem, but the pressure differential between the test chamber and the external environment during testing can generate forces that adversely affect the sensor. These forces can cause the sensor to deform, distorting the measurement results. To avoid this, the sensor must be designed to be extremely strong, which also leads to high costs. For high-precision applications or measurements, even the slightest deformation of the sensor during operation is unacceptable, so the strength requirements are particularly high, and the cost of achieving the required strength is correspondingly high.

[0008] The technical problem to be solved by the present invention is to provide a test system, which at least alleviates or prevents the problem of outgassing and mechanical load of the sensor.

[0009] This object is achieved by a test system having the features of claim 1. The advantage of this test system is that the mechanical loading of the sensor is reliably reduced or completely avoided by inexpensive means, while at the same time not neglecting outgassing problems.

[0010] According to the present invention, this is achieved by constructing a vacuum chamber associated with an opening on the side of the chamber wall facing away from the test chamber, and providing the vacuum chamber with a second vacuum generator to generate a negative pressure in the vacuum chamber independently of the vacuum in the test chamber. Specifically, the present invention provides for generating a negative pressure on the side facing away from the test chamber, which counteracts the vacuum or negative pressure in the vacuum chamber during testing. This reduces or prevents mechanical loading on the sensor caused by the pressure difference between the vacuum in the test chamber and the negative pressure in the vacuum chamber. In this case, the other electronic components of the sensor module are also arranged on the side of the support element facing away from the test chamber and are therefore located in the vacuum chamber. In particular, the sensor has a sensor surface that is arranged on the side of the support element facing the test chamber and is therefore located in the test chamber. The vacuum chamber is preferably designed to, together with the support element, completely surround or enclose the other electronic components of the sensor module, i.e., electronic components other than the sensor, which are preferably arranged on the side of the support element facing away from the test chamber. By controlling the vacuum generator independently of the first vacuum generator, the vacuum in the vacuum chamber can be adjusted to the desired level, thereby achieving the aforementioned advantages. Here, the vacuum is at least set so that the pressure in the vacuum chamber is lower than the ambient pressure of the test system. Preferably, the vacuum in the vacuum chamber is between the ambient pressure and the pressure in the vacuum chamber. Alternatively, the pressure in the vacuum chamber corresponds to the pressure in the vacuum chamber, thereby completely preventing mechanical stress on the sensor. This can prevent both outgassing of electronic components into the test chamber and mechanical overloading of the sensor, depending on the application, the object being measured, and the camera sensor being used. Optionally, a single vacuum chamber is assigned to multiple openings in the chamber wall, each of which is equipped with at least one sensor or sensor module. Alternatively, each of the multiple openings in the chamber wall is assigned a single vacuum chamber, each with its own vacuum generator, or multiple vacuum chambers are equipped with a common vacuum generator. In the latter case, the multiple vacuum chambers are interconnected so that the desired pressure can be generated in the vacuum chamber using a common vacuum generator.

[0011] According to a preferred extended design of the present invention, the negative pressure chamber is composed of a covering element placed on the chamber wall or the support element. The covering element is shaped so that on the one hand, it forms a negative pressure chamber together with the chamber wall and / or the support element, that is, a three-dimensional space with a specific volume greater than zero, and on the other hand, it is suitable for generating a vacuum between the covering element and the support element and / or the chamber wall with the sensor module, that is, in the negative pressure chamber or the volume. The covering element can be made of different sizes, thicknesses and different materials. The covering element is designed as a suction hood, in particular a suction bell or a basin-shaped / cup-shaped placement element. Therefore, a negative pressure chamber that matches the sensor module or sensor can be created on the support element or the chamber wall only by a suitable covering element. Here, the negative pressure chamber is formed between the covering element and the chamber wall of the test chamber and / or between the covering element and the support element. Therefore, the covering element is preferably designed to be placed on the chamber wall or the support element and to form a sealed connection with the chamber wall or the support element. The covering element has, for example, a rectangular longitudinal section, a cylindrical, polygonal, circular, in particular a perfectly circular or elliptical cross section and / or a bell shape.

[0012] Preferably, the negative pressure generator is a second vacuum generator. The second vacuum generator is, for example, of the same model as the first vacuum generator. Optionally, the second vacuum generator is of a lower power model because it is not necessary to completely balance the pressure difference between the test chamber and the negative pressure chamber.

[0013] Furthermore, it is preferably provided that the first and / or second vacuum generator is designed as a suction device, in particular as a backing vacuum pump, a single-stage vacuum pump or a turbo pump. Conventional vacuum generators are thus used, which are inexpensive to obtain and can reliably maintain vacuum and / or negative pressure for a long time.

[0014] According to a preferred embodiment of the present invention, the first vacuum generator and the negative pressure generator are designed and / or configured via a regulating device such that, at least during testing operation, the pressure in the test chamber is lower than the pressure in the negative pressure chamber. This ensures that any forces generated by the pressure differential in the direction of the test chamber are absorbed by the sensor. Deformations or loads on the camera sensor in the direction of the test chamber are less critical than in the opposite direction. This advantageous design ensures that reverse load conditions cannot occur.

[0015] Furthermore, it is preferably provided that a first pressure sensor is arranged in the test chamber and / or a second pressure sensor is arranged in the negative pressure chamber. These pressure sensors enable precise setting of the pressure in the test chamber and the negative pressure chamber, and in particular enable adjustment of the required pressure difference between the test chamber and the negative pressure chamber to a desired value or complete compensation of the pressure difference. Optionally, a third pressure sensor is also provided outside the test system, in particular on the outside of the test chamber that is not located within the negative pressure chamber, for detecting the ambient pressure. Optionally, the first and second pressure sensors are designed as differential pressure sensors.

[0016] Particularly preferably, a differential pressure sensor is arranged in the opening between the negative pressure chamber and the test chamber. This differential pressure sensor cooperates with both the test chamber and the negative pressure chamber to detect the differential pressure between the test chamber and the negative pressure chamber. This makes it particularly advantageous to detect and regulate the pressure ratio between the two chambers.

[0017] According to a preferred embodiment of the present invention, the vacuum generator is connected to the test chamber via a first connecting element, and / or the negative pressure generator is connected to the negative pressure chamber via a second connecting element. The first and / or second connecting element allows for an advantageous arrangement of the vacuum generator and / or negative pressure generator outside or inside the test chamber or negative pressure chamber, thereby ensuring optimal space utilization and positioning.

[0018] In particular, for this purpose, the corresponding connecting element is designed as a hose, a pipe or a flange.

[0019] Preferably, the support element has a circular, polygonal, particularly triangular or quadrilateral, symmetrical or asymmetrical outer contour. The circular outer contour ensures a favorable pressure distribution of the support element against the chamber wall during the test operation. In particular, the support element rests flatly with its outer edge or via a flange against the chamber wall, thereby preventing suction into the test chamber due to the negative pressure existing in the test chamber in a form-fitting manner. In particular, the chamber wall has a support region, particularly annular, corresponding to the edge region, with an opening formed in this support region, and the sensor is located in this opening.

[0020] Preferably, the support element has a flange, in particular annular, preferably circular, shape, on which the cover element can be arranged or is arranged in a sealing manner. The cover element thus cooperates with the support element, and the support element, in particular, rests in a sealing manner against the chamber wall, so that the support element is located between the cover element and the chamber wall. Alternatively, the cover element rests against the chamber wall.

[0021] Furthermore, it is preferably provided that the device for fixing the covering element to the support element or the chamber wall is arranged at one end on the support element or the chamber wall and / or at the other end on the covering element. This device enables, in particular, a form-fitting fixing of the covering element to the support element or the chamber wall. This ensures, in particular, that the covering element can be easily replaced to adapt to different boundary conditions.

[0022] The method according to the invention, having the features of claim 13, is characterized in that, for the test process, the vacuum generator and the vacuum generator are controlled so that a negative pressure is established in the vacuum chamber that is less than the ambient pressure but at most as low as the pressure in the test chamber. Ambient pressure is understood here to mean the air pressure in the immediate, especially direct, surroundings of the test system or test chamber and the vacuum chamber, outside the vacuum chamber and the test chamber, which should also be referred to as atmospheric pressure. This ensures that the sensor is subjected to a pressure differential that can only exert forces acting from the vacuum chamber toward the test chamber. If the pressure in the vacuum chamber is set so that it equals the pressure in the vacuum chamber, the camera sensor is not mechanically stressed by the pressure differential or the lack of a pressure differential. This achieves the aforementioned advantages. The current pressures in the test chamber and the vacuum chamber are preferably monitored in order to set or regulate a predetermined pressure differential between the test chamber and the vacuum chamber. For this purpose, a regulating device, such as a controller, a circuit, or a microprocessor, is used.

[0023] Further advantages and preferred features and feature combinations are apparent from the above description and the claims. The invention is explained in more detail below with reference to the accompanying drawings. In the drawings:

[0024] Figure 1 A simplified cross-sectional view showing an advantageous testing system;

[0025] Figure 2 showing a perspective view of a support element of a testing system; and

[0026] Figure 3 Shown is a simplified perspective view of a cover element of a testing system.

[0027] Figure 1 In a simplified sectional view, an advantageous test system 1 is shown, which according to the present embodiment is designed for carrying out an optical test process. For this purpose, the test system 1 has a test chamber 2 which is bounded by a chamber wall 3. In particular, the test chamber 2 is designed so that a vacuum can be generated therein. For this purpose, the test chamber 2 has a substantially closed chamber wall 3 and a Figure 1 The chamber wall 3 is only partially open, in particular to provide a closable opening (not shown in the figure) through which a test object can be introduced into the test chamber 2. The chamber wall 3 also has an opening 4, which is equipped with a sensor module 5 with a sensor 10 for testing, in particular measuring, the test object positioned in the test chamber.

[0028] The sensor module 5 has a support element 6, which is provided, for example, at Figure 2. According to the present embodiment, the support element 6 is designed to be circular and has a flange 7 on its outer edge and a recess 8 in the center, which is rectangular in this example. The flange 7 is therefore designed to be annular, in this example a circular ring, with a circular outer contour. The flange 7 is also designed for planar support on the side of the chamber wall 3 facing away from the test chamber 2. According to the present embodiment, the recess 8 is provided with a step 9, so that the sensor 10 can be arranged or arranged on the step 9 of the recess 8 and thus in the opening 4, in particular by means of the support 24, as shown. Figure 1 Preferably, a sealing element 25 , in particular elastically deformable, is arranged between the flange 7 and the chamber wall 3 , preferably in the form of an O-ring or other vacuum seal.

[0029] According to the present embodiment, the sensor 10 is designed as a camera sensor, which is located in particular in the recess 8 and is arranged or oriented on the carrier element 6 in the direction of the test chamber 2 in order to detect a test object positioned in the test chamber 2. Electronic components 11 designed for controlling the sensor 10 and for acquiring and optionally preprocessing the signals acquired by the sensor 10 are arranged on the side of the carrier element 6 facing away from the test chamber 2. The sensor 10 is embedded in the carrier element 6 in a sealing manner at the edge, so that the sensor 10 inserted into the opening 4 completely seals the recess 8 and the opening 4 at the edge and / or at the end, i.e., it seals the chamber wall 3 at this location.

[0030] The test chamber 2 is furthermore provided with a first vacuum generator 12 in the form of a suction device, which is optionally connected to the test chamber 2 via a connecting element 13 , in particular a tube.

[0031] The test system 1 also has a cover element 15. Figure 1 In the example shown, the cover element 15 is designed to be at least substantially cup-shaped or U-shaped in longitudinal section, with a particularly circular cross-section. The cover element 15 faces the chamber wall 3 with its open end and rests sealingly against the flange 7 of the support element 6 with its free end face 16, particularly via a further, particularly elastically deformable, sealing element 26, such as an O-ring. Consequently, the cover element 15 and the chamber wall 3 together form a negative pressure chamber 17 on the side facing away from the test chamber 2, in which the electronic component 11 is located. To this end, the cover element 15 is arranged on the chamber wall 3 such that it covers or surrounds the opening 4 and the sensor module 5 arranged in / on the opening 4.

[0032] The covering element 15 is connected, for example, via a connecting element 18 in the form of a tube to a second vacuum generator 19 , which is preferably likewise designed as a suction device.

[0033] By controlling the vacuum generator 12 , a negative pressure can be generated in the test chamber 2 . Preferably, a first pressure sensor 20 is also arranged in the chamber, which monitors the pressure prevailing in the test chamber 2 .

[0034] By controlling the vacuum generator 19, the vacuum in the vacuum chamber 17 can also be set. Preferably, a second pressure sensor 21 is also arranged in this chamber, by which the current vacuum in the vacuum chamber 17 can be monitored. Optionally, the pressure sensors 20, 21 form differential pressure sensors and are arranged near or in the opening 4. Alternatively or additionally, a differential pressure sensor 27 can be arranged on the carrier element 6, for example, in a further recess 28 next to the recess 8, which interacts with both the test chamber 2 and the vacuum chamber 17.

[0035] exist Figure 3 The figure shows, as an example, a perspective view of an embodiment of the cover element 15, exemplarily designed as a suction cup. Optionally, the cover element 15 can be designed as a suction bell. The cover element 15 advantageously has a flange-shaped support section 22, which is designed for sealing support on the chamber wall 3, in particular the support element 6, and is particularly designed to partially accommodate a sealing element 26. Optionally, and as shown in the figure, a plurality of threaded holes 29 or other holes designed for fixing are preferably formed in the support section 22, through which fixing screws can be passed to mount the cover element on the chamber wall. Preferably, the flange 7 and the chamber wall 3 have threaded holes corresponding to the threaded holes 29. For assembly, the fixing screws are preferably subsequently inserted through the aligned threaded holes and tightened in such a way that the corresponding threaded holes are sealed in a medium-tight manner, in particular by at least one sealing element. As mentioned above, the cover element 15 is advantageously designed to be circular in cross-section to ensure favorable force transmission and distribution. Alternatively, the cover element 15 is designed for sealing support directly on the chamber wall 3 next to the support element 6. Optionally, the chamber wall 3 has a flange or an outward turn or projection in the form of the aforementioned flange.

[0036] exist Figure 1The controller 23 shown in the example is designed to acquire the measured values ​​of sensors 20 and 21 and to control the vacuum generator 12 and the vacuum generator 19. To conduct the test process, the test chamber 2 is evacuated by controlling the vacuum generator 12. This creates a vacuum, ensuring favorable measurement results. Furthermore, the vacuum generator 19 is controlled to also generate a negative pressure in the vacuum chamber 17, which forms another vacuum. The negative pressure set in the vacuum chamber 17 is lower than the ambient pressure of the test system 1 and is at most as low as the negative pressure in the test chamber 2. This ensures that the pressure difference between the test chamber 2 and the vacuum chamber 17 always forces the sensor 10 or camera sensor in the direction of the test chamber 2. This ensures that the pressure difference always forces the sensor 10 or camera sensor in the direction of the test chamber 2. This ensures optimal measurement results. Optionally, the same negative pressure can be set in the test chamber 2 and the vacuum chamber 17, so that the sensor 10 is not mechanically stressed during the test process.

[0037] Since the sensor 10 faces the test chamber 2 and the other electronic components 11 are located in the negative pressure chamber 17 , the electronic components 7 can only release air into the negative pressure chamber 17 , that is, the purity or cleanliness of the test chamber 2 is maintained during the test.

[0038] This results in an advantageous test system 1 which, on the one hand, prevents contamination of the test chamber 2 due to outgassing effects of electronic components and, on the other hand, ensures safe operation of the camera sensor 10 by avoiding mechanical loads.

Claims

1. A test system (1) comprising a test chamber (2) in which a test object can be arranged, wherein: The test chamber (2) has at least one chamber wall (3) defining the test chamber (2), wherein the test chamber (2) is provided with a first vacuum generator (12) so as to be able to generate a vacuum in the test chamber (2), and wherein the chamber wall (3) has at least one opening (4) provided with at least one sensor module (5), wherein the sensor module (5) has a support element (6) and a sensor (10), in particular an optical sensor, a temperature sensor, a pressure sensor, a gas sensor or a camera sensor, the support element being arranged on the chamber wall (3) in such a manner as to close the opening (4), the sensor being arranged on the side of the support element (6) facing the test chamber (2), characterized in that a negative pressure chamber (17) assigned to the opening (4) is constructed on the side of the chamber wall (3) facing away from the test chamber (2), and the negative pressure chamber (17) is provided with a negative pressure generator (19) so as to be able to generate a negative pressure in the negative pressure chamber (17) independently of the vacuum in the test chamber (2).

2. The test system according to claim 1, wherein: The negative pressure chamber (17) is formed by a covering element (15) placed on the chamber wall (3) or the support element (6).

3. The test system according to any one of the preceding claims, characterized in that The negative pressure generator (19) is a second vacuum generator.

4. The test system according to any one of the preceding claims, characterized in that The first vacuum generator (12) and / or the second vacuum generator are each designed as a suction device.

5. The test system according to any one of the preceding claims, characterized in that The first vacuum generator (12) and the vacuum generator (19) are designed and / or regulated by a regulating device in such a way that, at least during test operation, the pressure in the test chamber (2) is lower than the pressure in the vacuum chamber (17).

6. A test system according to any one of the preceding claims, characterized in that A first pressure sensor (20) is arranged in the test chamber (2), and / or a second pressure sensor (21) is arranged in the negative pressure chamber (17).

7. A test system according to any one of the preceding claims, characterized in that A differential pressure sensor (25) is arranged in the opening between the negative pressure chamber (17) and the test chamber (2).

8. A test system according to any one of the preceding claims, characterized in that The vacuum generator (12) is connected to the test chamber (2) via a first connecting element (13), and / or the negative pressure generator (19) is connected to the negative pressure chamber (17) via a second connecting element (18).

9. The test system according to any one of the preceding claims, characterized in that The corresponding connecting elements (13, 18) are designed as hoses, pipes or flanges.

10. The test system according to any one of the preceding claims, characterized in that The support element (6) has a circular, polygonal, symmetrical or asymmetrical outer contour.

11. The test system according to any one of the preceding claims, characterized in that The carrier element (6) has a flange (7) on which the covering element (15) can be arranged in a sealing manner or is arranged.

12. The test system according to any one of the preceding claims, characterized in that The device for fixing the covering element (15) on the support element (6) or the chamber wall (3) is arranged on the support element (6) or the chamber wall (3) at one end and / or on the covering element (15) at the other end.

13. A method for operating a test system according to any one of claims 1 to 12, characterized in that: For the test process, the vacuum generator (12) and the vacuum generator (19) are controlled so that a vacuum is set in the vacuum chamber (17), which is less than the ambient pressure but at most as low as the pressure in the test chamber (2).

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