Sensing device and metering system incorporating such sensing device

Abstract

The invention relates to a sensing device and a metering system incorporating such a sensing device. A sensing device for a metrology system includes a measurement region and a body. The body comprises at least one light source adapted to emit light onto a workpiece and at least one sensor arranged to receive the light from the light source after the light has been reflected by the workpiece. The sensing device also includes at least one heat exchanger having an inlet and an outlet for exchanging heat between the measurement region and an exterior of the measurement region.

Description

Technical Field

[0001] The present disclosure generally relates to a sensing device for a metering system, and to a metering system incorporating such a device. The present disclosure further relates to a method for controlling temperature in a metering system. Background Art

[0002] Measuring parts using advanced metrology systems is becoming an increasingly important part of manufacturing today.

[0003] Non-contact inspection of parts is an area within metrology that shows great results and can significantly reduce the time required to inspect a part compared to measurement systems that require the workpiece to be brought into contact with, for example, a probe. In a non-contact metrology system, a light beam such as a laser is typically used for measurement, such that the laser beam is directed at the workpiece and a reflection of the laser beam is received by a sensor.

[0004] As the complexity of manufactured parts increases and as technology advances, minimizing measurement errors and increasing measurement capabilities become increasingly important. This is especially true in technical fields where accuracy and repeatability are critical.

[0005] Therefore, any improvement to a non-contact metrology system that improves accuracy or increases repeatability, for example by reducing the variance between measurements, is a welcome benefit.

[0006] Therefore, improvements are needed when it comes to contactless metering systems. Summary of the invention

[0007] It is an object of the present invention to address at least some of the above problems and issues. It is an object of embodiments of the present invention to provide a sensing device for a metrology system comprising a heat exchanger such that heat can be transferred away from a measurement area of ​​the sensing device in order to improve the performance of the sensing device and / or the performance of the metrology system as a whole.

[0008] According to one aspect, a sensing device for a metrology system is provided, the sensing device having a measurement region and comprising a body. The body comprises at least one light source and at least one sensor, wherein the at least one light source is adapted to emit light onto a workpiece, and the at least one sensor is adapted to receive the light from the light source after the light is reflected by the workpiece. The sensing device further comprises at least one heat exchanger, the at least one heat exchanger comprising an inlet and an outlet, the inlet and the outlet being used to exchange heat between the measurement region and an exterior of the measurement region.

[0009] According to another aspect, a metrology system for inspecting a three-dimensional workpiece is provided. The metrology system comprises a housing containing at least one sensing device according to embodiments described herein, wherein the heat exchanger of the sensing device is adapted to exchange heat between an interior of the housing and an exterior of the housing.

[0010] According to another aspect, a method for improving the performance of a metrology system according to embodiments herein is provided. The method comprises exchanging heat between a measuring area of ​​a sensing device inside the housing and outside the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The solution will now be described in more detail by means of exemplary embodiments and with reference to the accompanying drawings, in which:

[0012] Figure 1 is a view of a sensing device according to an embodiment.

[0013] Figure 2 Another view of a sensing device according to an embodiment is shown.

[0014] Figure 3 A sensing device according to another embodiment is shown.

[0015] Figure 4 is a diagram of a metering system including three sensing devices according to an embodiment.

[0016] Figure 5 The steps of a method according to an embodiment are schematically shown. DETAILED DESCRIPTION

[0017] Briefly, the present disclosure relates to a sensing device for a metrology system. The sensing device includes a body having at least one light source, such as a laser, e.g., a laser profiler, the body being adapted to measure a workpiece by emitting a light beam on the workpiece and then receiving the light beam with a sensor after the light beam is reflected by the workpiece. The sensing device also includes a heat exchanger attached to or incorporated into the body. The heat exchanger may be a fluid heat exchanger using air as a cooling fluid.

[0018] It has been found that the performance of various components in a non-contact metrology system, including sensors and light sources, can be negatively impacted by excessive heat. This is at least in part due to the heat distorting the light beam used to measure the workpiece, but the heat can also negatively impact other components in the system. However, unless the accuracy required by the system is very high, such as on a sub-micron scale, the negative impact on performance is usually not noticeable.

[0019] The present disclosure is based on the recognition that the performance of a contactless metering system can be improved if heat can be moved away from a measuring area of ​​a sensor in a good manner. To this end, an improved sensing device is provided that includes a heat exchanger that can exchange heat between a measuring area of ​​the sensing device and outside of the measuring area. In some embodiments, when the sensing device is installed in a closed metering system, the sensing device can be connected to the outside of the enclosed area so that heat can be exchanged between the enclosed area and the outside.

[0020] One way that the performance of the sensing device can be improved is that the standard deviation between subsequent measurements can be reduced. During testing, it has been found that the standard deviation of a high-precision sensing device can be improved from a few microns to less than one micron. In some tests, the standard deviation was about 2.3 (two and three tenths) microns without any heat exchange, and about 0.6 (six tenths) microns with heat exchange using a sensing device as described herein.

[0021] Although the above implementation is based on noting that too much heat has a negative impact on the sensor of the contactless metrology system, the idea of ​​exchanging heat can also be naturally applied in the other direction. In other words, in the case where the temperature is lower than the optimal temperature of the system, the heat can be transferred to the measurement area around the sensing device instead of away from the sensing device. Therefore, the present disclosure is not only focused on removing heat from the sensing device, but also on controlling the temperature in the measurement area around the sensing device.

[0022] It may also be the case that the main problem is not the temperature of the sensor and / or the metrology system itself, but the temperature gradient between the laser and / or the sensor and the ambient temperature of the metrology system. Therefore, in some embodiments, the present disclosure may be viewed as a method for reducing the temperature gradient between the sensor and / or the laser and / or the sensing unit and the ambient air of the metrology system and / or the ambient temperature of the workpiece.

[0023] In tests that have been performed in conjunction with the present invention, it has been demonstrated that the temperature of lasers and / or sensors used in a metrology system can be reduced from about 30 degrees Celsius to about 15 to 20 degrees Celsius. The temperature inside the metrology system can be controlled to be maintained at about 20 degrees Celsius, with small temperature gradients inside the metrology system.

[0024] For purposes of this disclosure, the term "non-contact metrology system" is intended to refer to a metrology system that has the ability to measure a workpiece without having any mechanical parts physically contact the workpiece.

[0025] refer to Figure 1 , shows a sensing device 100 according to an embodiment.

[0026] The sensing device 100 comprises a body 105. The body 105 comprises a light source 110, such as a laser, which may be a line laser. The light source 110 is adapted to emit a light beam 115 onto a workpiece 150 so as to measure the workpiece 150 with the aid of a sensor 120 adapted to receive the light beam 115 after it has been reflected by the workpiece 150. The sensor 120 may be a camera having a field of view 125, wherein the field of view 125 is aimed at the portion of the workpiece 150 intended to be measured. In some embodiments, the sensor 120 is a CMOS type sensor.

[0027] In some embodiments, the body has a housing for electronics and wiring associated with components of the body, such as sensor 120 and light source 110. Heat generated by components of the sensing device, such as sensor 120 and light source, may be generated and / or contained in the body, at least to some extent.

[0028] The body 105 further comprises a heat exchanger 130 arranged to exchange heat from the inside of the measurement region 160 to the outside of the measurement region 160. In some embodiments, the heat exchanger 130 is adapted to transfer heat from the body 105 into the heat exchanger 130 and then from the heat exchanger to the outside of the measurement region 160.

[0029] For purposes of this disclosure, measurement region 160 is intended to mean the area around the sensor where the sensor is negatively affected by temperature changes. Measurement region 160 is typically a volume, but in some embodiments it may be a two-dimensional area.

[0030] In embodiments where the sensing device 100 is located inside a metrology system that includes a housing, the measurement region 160 may be a portion of the housing of the metrology system or the entire housing.

[0031] The body 105 may be made of any suitable material, preferably a material that is relatively inexpensive and has a relatively high thermal conductivity, such as aluminum.

[0032] In some embodiments, the majority of the body 105 comprises a material that is thermally non-conductive or at least has very low thermal conductivity, while the portion of the body 105 that faces the heat exchanger 130 comprises a thermally conductive material.

[0033] In some embodiments, heat exchanger 130 may include an inlet 135 and an outlet 137 (see, e.g., Figure 4 ) for exchanging heat between the measurement region 160 and the outside of the measurement region 160. In some embodiments, the heat exchanger 130 may be a phase change heat exchanger. In some embodiments, the phase change heat exchanger may include a liquid as a cooling fluid that changes phase to a vapor during the heat exchange process.

[0034] In some embodiments, the fluid in the heat exchanger 130 can be air. In some embodiments, the fluid can be a liquid, such as water, ethylene glycol, or a dielectric fluid. In some embodiments, the heat exchanger 130 also includes a cooler or heater 139, which is positioned at the inlet 135 and is suitable for cooling or heating the heat exchanger fluid before the heat exchanger fluid enters the inlet of the heat exchanger. In some embodiments, the cooler 139 is a vortex tube.

[0035] In some embodiments, the heat exchanger 130 comprises aluminum. In some embodiments, the heat exchanger 130 comprises copper. In some embodiments, the heat exchanger 130 comprises a plastic composite material.

[0036] In some embodiments, heat exchanger 130 may include cooling channel 133 or multiple cooling channels suitable for transferring heat through the heat exchanger. In some embodiments, heat exchanger may include one cooling channel connected to inlet 135 at one end and to outlet 137 at one end.

[0037] In some embodiments, the outlet 137 of the heat exchanger can be relatively long so as to transfer heat relatively far away from the light source 110 and the sensor 120. In some embodiments, the outlet of the heat exchanger can be between 0.1 and 2 meters. In some embodiments, it can be about 1 meter.

[0038] In some embodiments, the sensing device 100 may further include a power cord 170 suitable for connecting the sensing device 100 to a power source.

[0039] In some embodiments, the sensing device 100 further includes a temperature sensor 145, which in some embodiments may also be positioned on the body 105. In some embodiments, such as Figure 1 In the illustrated embodiment, the temperature sensor 145 is positioned at a distance away from the main body 105 , but is still connected to the main body 105 via a connection device 147 .

[0040] In such an embodiment, the temperature sensor is arranged to measure the temperature of the measurement region 160 , and thus the temperature of the measurement region 160 of the sensing device 100 is defined as the temperature measured by the sensor associated with the sensing device 100 .

[0041] In some embodiments, the sensing device 100 may also include one or more heat sinks 140 for facilitating heat exchange performed by the heat exchanger. The heat sink may include any suitable material for conducting heat, such as aluminum or copper.

[0042] In some embodiments, the heat exchanger 130 is attached to the body 105 of the sensing device, for example, by using a bracket in the body 105. Such brackets may be conventionally intended to secure the body 105 in a metering system. In some embodiments, the heat exchanger 130 may be incorporated into the body 105 so that it is integral with the body 105.

[0043] In some embodiments, sensing device 100 may also include a bracket suitable for securing sensing device 130 in a metering system. In embodiments where the heat exchanger is attached to body 105 via brackets in body 105, heat exchanger 130 may include a similar or same type of bracket on the exterior.

[0044] See now Figure 2 , another view of the sensing device 100 is shown. Figure 2 In the illustrated embodiment, the sensing device 100 includes a cooling channel 133 that is housed inside the heat exchanger 130. The cooling channel 133 is connected to an inlet 135 at one end and to an outlet 137 at one end, and is adapted to transfer heat through the heat exchanger 130. In some embodiments, for example Figure 2 In the illustrated embodiment, the heat exchangers are located on two faces of the body 105 and have an L-shape.

[0045] In some embodiments, such as Figure 3 In the illustrated embodiment, heat exchangers 130 are positioned on three faces of body 105. In some embodiments, heat exchangers may be positioned on four faces of body 105, typically excluding the face where light source 110 and sensor 120 are positioned and the face where inlet 135 and outlet 137 are positioned.

[0046] See now Figure 4 , will now further refer to Figure 1 A metrology system 200 incorporating at least one sensing device 100 according to the present disclosure is described. Figure 4 A cross-section of such a metrology system 200 is shown comprising three sensing devices 100 according to embodiments described herein.

[0047] The metering system 200 is preferably a contactless metering system, comprising an enclosure 205 (represented by dashed lines), such as a cabinet, wherein the enclosure has a mechanism for opening and closing an entrance to the enclosure, such as a door (not shown). The enclosure may also include a wall or other barrier separating an interior of the enclosure from an exterior of the enclosure.

[0048] The metrology system 200 typically, but not necessarily, also includes other components, such as a stage 220 on which the workpiece 150 can be positioned. The stage 220 can be a rotary stage that is adapted to rotate so that the workpiece 150 is scanned by the sensing device while the stage is rotating or while the workpiece 150 is moved by a linear translation stage.

[0049] In some embodiments, the metering system 200 may further include a cooling unit adapted to cool the interior of the housing 205. The cooling unit may be a piezoelectric cooling unit. The cooling unit may include one or more fans.

[0050] The system 200 may also include a fixture 230 on which the sensing device 100 is positioned and / or fastened. In some embodiments, the fixture 230 is positioned on a movable component (such as a movable arm) so that the sensing device 100 can be moved around inside the housing. The sensing device 100 can be attached to the fixture 230 via a bracket and positioned on the sensing device body 105 or on the heat exchanger 130.

[0051] The system 200 also includes at least one sensing device 100 according to any embodiment described herein positioned inside the housing 210. In some embodiments, for example Figure 4 In the embodiment shown in , the metering system 200 includes a plurality of sensing devices 100. In some embodiments, the metering system 200 includes at least two sensing devices 100.

[0052] In some embodiments, each sensing device 100 is associated with a corresponding measurement region. In some embodiments, the measurement region may be the same as the interior of the housing. In some embodiments, the temperature of the measurement region of a particular sensing device is defined as the temperature measured by the sensor associated with the sensing device.

[0053] In some embodiments, particularly in embodiments where the sensing device 100 of the metering system 200 does not include its own temperature sensor 145, the metering system may include a temperature sensor for the sensing device. The temperature sensor for the sensing device may then be located at a distance from the sensing device 100 without being physically connected to the sensing device.

[0054] In some embodiments, the metering system further comprises a temperature detector located inside the housing and adapted to measure the temperature of the housing. In some embodiments, the temperature detector of the metering system 200 may be used in conjunction with a temperature sensor of the sensing device or the metering system itself, which will be described in detail later in this disclosure.

[0055] By incorporating the sensing device inside the housing 205 of the metering system 200, the heat exchanger 130 of the sensing device can be connected to the outside of the housing 205, and heat can be exchanged from the inside of the housing to the outside of the housing. In some embodiments, the housing is only partially enclosed relative to the outside of the metering system. In some embodiments, the housing is completely enclosed from the outside.

[0056] When operating at the level of accuracy sometimes required of a non-contact metrology system, such as the system 200 described herein, there may be relevant advantages in exchanging heat between the interior of the housing and the exterior of the housing, rather than simply exchanging heat from an area surrounding the sensing device's laser 110 and / or sensor 120 to another area of ​​the interior of the housing. In the event that heat is transferred out of the housing 205, such heat is typically heat generated by the operation of the sensing device 105 and / or from other parts of the metrology system 205.

[0057] See now Figure 5 , will now further refer to Figure 1 and Figure 2 A method for improving the performance of a metrology system 200 according to the present disclosure is described. In some embodiments, the method may be a method for improving the performance of a sensor in the metrology system 200. In some embodiments, the method may be a method for exchanging heat between a measurement region of a sensing device and an exterior of the measurement region.

[0058] The method includes, in the metering system 200, exchanging 406 heat between an interior of the housing 205 and an exterior of the housing 205. In some embodiments, the exchanging 406 includes transferring heat from an interior of the housing 205 of the metering system 200 to an exterior of the housing 205. In some embodiments, the exchanging 406 includes transferring heat from an exterior of the housing 205 of the metering system 200 to an interior of the housing 205. The exchanging 406 is performed such that there is no, or at least no significant, heat exchange from the heat transferred to the interior of the housing 205 using the exchanger.

[0059] In an embodiment where the heat exchanger 130 of the sensing device 100 is a fluid heat exchanger using air as the fluid, exchanging 406 includes introducing the fluid into the heat exchanger, where the fluid is heated or cooled before being introduced into the heat exchanger, depending on whether the metering system 200 is to be cooled or heated. The heating or cooling can be performed by a cooler or heater 139 of the sensing device, where the cooler or heater 139 is located outside the housing. The exchanging 406 then also includes conducting heat out of the housing or into the housing by passing the fluid through the heat exchanger.

[0060] As will be appreciated, if the method is performed so as to cool the metering system 200, heat will be exchanged from the interior of the housing to the exterior of the housing. If the method is performed so as to heat the metering system 200, heat will be exchanged from the exterior of the housing to the interior of the housing.

[0061] In some embodiments, the exchange 406 may be preceded by detecting 402 a temperature in the measurement region 160 of the sensing device and determining 404 that the detected temperature deviates from a desired temperature. Depending on whether the detected temperature is below or above the desired temperature, the exchange will include exchanging heat from or to the interior of the metering system 200. The detection 402 may be performed by a temperature sensor of the sensing device 100 or a temperature detector of the metering system 200.

[0062] In some embodiments, the method includes continuously exchanging 406 heat between the interior of the housing and the exterior of the housing as long as the metering system 200 and / or the sensing device 100 are powered.

[0063] In some embodiments, detection 402 may be performed by a temperature sensor of the sensing device and a temperature detector of the metering system. In such embodiments, detection 402 may include detecting a first temperature using a temperature detector of the metering system 200 and then comparing it to a second temperature detected by the temperature sensor of the sensing device 100. In the event that the first temperature is different from the second temperature, it may be used as a determination of a temperature deviation from an expected temperature, where it is important to have the same temperature everywhere within the metering system 200.

[0064] In some embodiments, both the first temperature and the second temperature may deviate from a desired temperature, wherein the desired temperature is known or determined prior to detecting 402. Thus, in some embodiments, the method may first include the step of setting or determining the desired temperature prior to detecting 402.

[0065] In some embodiments, the sensing device 100 and / or the metering system 200 may include processing circuitry and memory. The processing circuitry may include one or more programmable processors, application specific integrated circuits, field programmable gate arrays, or a combination thereof adapted to execute instructions. The memory contains instructions executable by the processing circuitry, whereby the sensing device and / or system may be operated to perform a method according to any embodiment described herein.

[0066] The part of the sensing device 100 and / or the metering system 200 that performs the method may be a set of devices, wherein the functions for performing the method are distributed on different physical entities or virtual devices of the system. In other words, it may be a cloud solution, i.e., parts of the device / system may be deployed as cloud computing resources that may be distributed in the system.

[0067] According to other embodiments, the device and / or system may further include a communication unit, which may be considered to include conventional means for communicating with associated devices. The instructions executable by the processing circuit may be arranged as a computer program stored in, for example, a memory. The processing circuit and the memory may be arranged in a sub-arrangement. The sub-arrangement may be a microprocessor and appropriate software and storage means therefor, a programmable logic device, a PLD or other electronic components / processing circuits configured to perform the above method.

[0068] The computer program may include computer readable code means which, when run in the sensing device 100 and / or the metering system 200, cause the device / system to perform the method steps described in any of the described embodiments. The computer program may be carried by a computer program product connectable to the processing circuit. The computer program product may be a memory. The memory may be implemented as, for example, a RAM (random access memory), a ROM (read only memory) or an EEPROM (electrically erasable programmable ROM). In addition, the computer program may be carried by a separate computer readable medium, such as a CD, a DVD or a flash memory, from which the program may be downloaded to the memory. Alternatively, the computer program may be stored on a server or any other entity connected to the device 100 and / or the system 200. The computer program may then be downloaded from the server to the memory.

[0069] Although the above description contains a number of specific contents, these should not be interpreted as limiting the scope of the concept described herein, but rather as providing only an illustration of some exemplary embodiments of the concept described. It should be understood that the scope of the concept currently described fully encompasses other embodiments that are obvious to those skilled in the art, and the scope of the concept currently described is therefore not limited. Unless explicitly stated, reference to an element in the singular is not intended to mean "one and only one", but rather "one or more". All structural and functional equivalents of the elements of the above-described embodiments known to those of ordinary skill in the art are expressly incorporated herein by reference, and are intended to be covered herein. In addition, the device or method does not necessarily solve each problem that the concept currently described seeks to solve, because it is covered herein. In a figure representing a method step, a dotted line generally indicates that the feature within the dotted line is optional.

Claims

1. A sensing device for a metering system, the sensing device having a measurement area and comprising: A subject, the subject comprising: at least one light source arranged to emit light onto a workpiece; at least one sensor arranged to receive the light from the light source after the light is reflected by the workpiece; and At least one heat exchanger comprising an inlet and an outlet for exchanging heat between the measurement region and an exterior of the measurement region.

2. The sensing device according to claim 1, wherein: The heat exchanger is a fluid heat exchanger.

3. The sensing device according to claim 2, wherein: The fluid is air. 4 . The sensing device according to claim 3 , further comprising a temperature sensor for detecting a temperature in the measurement area of ​​the sensing device. The sensing device according to claim 4 , further comprising a heat sink.

6. The sensing device according to claim 5, wherein: The heat exchanger is attached to the body.

7. The sensing device according to claim 6, wherein: The heat exchanger is attached to the body via brackets of the sensing device, wherein the heat exchanger comprises similar brackets.

8. The sensing device according to claim 7, wherein: The heat exchanger is integrated into the body.

9. The sensing device according to claim 8, wherein: The heat exchanger is located inside the main body.

10. A metrology system for inspecting a three-dimensional workpiece, comprising: Housing, comprising: At least one sensing device according to claim 1, wherein the heat exchanger of the sensing device is arranged to exchange heat between the interior of the housing and the exterior of the housing.

11. A metering system according to claim 10, comprising at least two sensing devices according to claim 1.

12. The metering system of claim 11, further comprising a temperature sensor located inside the housing for each sensing device.

13. The metering system of claim 12, further comprising a temperature detector for sensing a temperature of the metering system inside the housing.

14. A method for improving the performance of a metering system according to claim 10, wherein: The method comprises: Heat is exchanged between a measuring area of ​​a sensing device inside the housing and the outside of the housing.

15. The method according to claim 14, wherein: The method further comprises, before the exchanging: detecting the temperature of the measurement area; and It is determined that the temperature deviates from the desired temperature.

16. The method according to claim 15, wherein: The heat exchange is continuously performed while the light source is functioning.

17. The method according to claim 16, wherein: The determination is further based on a temperature detected by a temperature sensor of the metering system.

Images