Visualization system, method for temperature stabilization of current optical system state of visualization system

Abstract

The invention relates to a method for temperature stabilization of a current optical system state of a visualization system and a visualization system. In order to operate a visualization system (1) in an improved manner, the visualization system comprises imaging optics (2) with adjustable zoom optics (3) and also adjustable focusing optics (4), according to the invention, at least one detection temperature (12) in the imaging optics (2) is detected directly and / or indirectly (e.g. By estimation) by means of at least one temperature detector (27), and once a currently detected temperature change (11) with respect to the detection temperature (12) exceeds a temperature threshold value (18), the detection temperature (12) is detected. If so, the focusing optics (4) and / or the zoom optics (3) are actively adjusted by means of a stabilization system (9) comprising one or more stabilization adjustment loops (10).

Description

Field of the Invention

[0001] The present invention relates to a method for temperature stabilization of the current optical system state of a visualization system (especially a medical one). The system includes imaging optics having: an adjustable zoom optics for determining the current zoom level; and an adjustable focusing optics for determining the current spatial position of the focal plane; and having at least one image sensor. In the method, at least one image of an object observed with the visualization system, such as a surgical area, is recorded by means of the at least one image sensor. Furthermore, the current optical system state is stabilized against temperature-induced fluctuations within the imaging optics by means of the method, the current optical system state including the current optical zoom level and the current spatial position of the focal plane.

[0002] Furthermore, the present invention relates to a visualization system which can preferably be designed as part of a robotic system and / or a medical visualization system. The visualization system has imaging optics which includes the following components: an adjustable zoom optics for determining the current optical zoom level; an adjustable focusing optics for determining the current spatial position of the focal plane; and at least one image sensor for recording at least one image of an object observed with the visualization system, such as a surgical area, and finally including at least one temperature detector which is set up for directly sensorially measuring and / or indirectly non-sensorially detecting at least one current temperature change of the detection temperature within at least one detection area. Background Art

[0003] Medical visualization systems in the form of endoscopes are already known in the prior art and are used as part of a robotic system in neurosurgery in order to visualize the surgical area for a neurosurgeon in an enlarged view on a display screen. In such an application, the endoscope is arranged by a robotic arm at different working distances (typically 200 - 550 mm) spaced apart from the surgical area to be observed, wherein the visualization system is designed with respect to a zoom optics for changing the optical zoom level (and thereby changing the corresponding image portion recorded by means of the image sensor) and a focusing optics for spatially determining the focal plane.

[0004] In such a visualization system, typically in addition to the stepper motors for adjusting the zoom optics and the focusing optics, a further plurality of electronic structural units are also installed, such as an image sensor, adjustment and readout electronics, and an electronic image processing unit. All of these electronic components exhibit electrical power losses which lead to heating of the overall system, especially the imaging optics.

[0005] During the operation of the visualization system, each component first heats up from an ambient temperature of approximately 25 °C to a temperature in the range of 40 °C to approximately 60 °C in a "warm-up" phase. During its own operation, the visualization system can also generate additional heat. This warm-up typically occurs before the surgeon generally begins to work with the visualization system. In this regard, this initial heating is relatively insignificant.

[0006] However, during the use of the visualization system, temperature changes of 10 °C and more can occur for different reasons (changing electrical loss heat, temperature changes in the operating room, etc.). In the worst case, this can lead to a focal plane change of several centimeters (up to 80 mm has been observed in extreme cases).

[0007] The change in temperature here not only affects the change in the refractive index of the corresponding lens material, but also the shape, its position, and if possible its orientation / tilt of the corresponding lens change. It should also be considered here that the mechanical structure in which the lens is held also undergoes thermo-mechanical stress, which affects the optical function. All these effects generally result in: the focal lengths of the focusing optics and the zoom optics and thus the resulting zoom level can change significantly due to temperature. Such thermal drift of the imaging optics can be particularly disturbing for the surgeon when using the visualization system.

[0008] This applies in particular when the visualization system has multiple parallel optical channels, for example for stereoscopic vision, and the spatial position of the observed object should be determined based on the measurement data of these two channels (such a design can also be provided in the visualization system according to the invention). Such a solution allows: optical tracking of, for example, measurement functions or objects within the real-time video image. In addition, this is also of interest, for example, for the documentation of medical operations or also allows for the specific positioning of objects within the field of view observed with the aid of a robotic system. However, all these functions are affected by the thermal drift described above.

[0009] In stereoscopic display, disturbing effects can also occur if the focal planes or zoom levels (and thus the size of the field of view) of the two stereoscopic paths change differently strongly due to temperature changes. Such mutual drift of the two optical channels of the visualization system can be caused, for example, by a non-uniform temperature distribution within the camera, and / or because the two optical paths are located at different positions within the overall system and are affected differently strongly by system components generating residual heat. Summary of the Invention

[0010] Against this background, the object of the present invention is to effectively counteract temperature effects, in particular thermal drift, which adversely affect the performance of the visualization system.

[0011] To achieve the above object, the features of claim 1 of the method according to the present invention are provided. In particular, to achieve the above object, in the method for temperature stabilization of the current optical system state of the visualization system as described at the beginning, it is proposed according to the present invention that: by means of a stabilization system including at least one stabilization adjustment loop, at least one current temperature change of the detection temperature in at least one detection area within the visualization system is continuously detected directly or indirectly, and once at least one temperature threshold for the at least one current temperature change is exceeded, the focusing optical device and / or the zoom optical device is actively adjusted by the at least one stabilization adjustment loop.

[0012] The direct detection of the change in the detection temperature can be achieved, for example, by means of a temperature sensor. However, the change can also be detected indirectly, for example, by means of a sensor that detects the length change caused by the temperature change or other temperature-induced mechanical changes within the imaging optical device.

[0013] In other words, the present invention thus proposes to stabilize the optical system state by means of a stabilization system with at least one stabilization adjustment loop and by detecting at least one temperature change of the detection temperature. Thereby, the shift caused particularly thermally of the zoom optical device and / or the focusing optical device can be balanced by corresponding readjustment (active readjustment based on the directly or indirectly detected temperature change). Thereby, it can be achieved that the temperature adjustment is carried out at a determined operating point - the user of the visualization system has just selected this operating point (i.e., for example, for the just set zoom level and / or the specific currently selected focal plane) - which keeps the operating point stable, more precisely, in particular according to whether and how the temperature within the visualization system (in particular the temperature within the housing that encloses the imaging optical device) changes.

[0014] Preferably, in the method, at least two detection temperatures can be evaluated, which are detected in different detection areas within the visualization system, preferably within the imaging optical device. Such a spatially distributed detection of the temperature is not mandatory; however, it can be advantageous and thus meaningful, for example, for stabilizing the optical zoom. The detection of the current temperature change can be achieved directly as described above (for example, by means of temperature measurement) or indirectly, for example, by detecting the position change caused by the temperature, from which the temperature change that has occurred can be inferred.

[0015] A visualization system can for example be designed as a medical visualization system and / or as a stereoscope or a microscope or an endoscope, for example. This results in a further distinct advantage of the method according to the invention, namely that a corresponding temperature stabilization, for example within the scope of a stereoscopic surgical operation, avoids the stereoscopically acquired images of the surgical area being distorted due to temperature fluctuations and thus due to thermally induced changes in the zoom level and / or the spatial position of the focusing optics that may thereby change. Due to the temperature stabilization of the current optical system state of the visualization system, it is thus possible to ensure an unchanged high quality of the acquired images or the acquired image sequences, for example real-time video images. If the visualization system has a stereoscopic imaging system, then by means of the invention it is possible to prevent the corresponding optical system states of the corresponding optical channels from drifting relative to one another.

[0016] The visualization system can then be equipped with, for example, two parallel optical channels and two image sensors each, thereby implementing a stereoscopic imaging system that provides a spatial impression for the surgeon. The visualization system can also detect objects, such as surgical instruments, in real-time video images here. The visualization system can furthermore be set up to calculate the spatial position of the corresponding object in the world coordinate system on the basis of a model of the stereoscopic optics and using triangulation. For this purpose, it can be provided that first a location position in the camera coordinate system is assigned to each pixel of the image sensor within the corresponding camera coordinate system (in particular the left or right image sensor). Subsequently, a corresponding coordinate in the world coordinate system can be assigned to this location on the basis of the or a set zoom level and the focal plane / set current position of the focusing optics. Such a scheme allows, for example, a measurement function or the optical tracking of objects in real-time video images. This is also of interest, for example, for the documentation of medical operations and / or this can also enable the specific positioning of objects within the field of view observed with the aid of a robotic system.

[0017] The problem that exists in principle is that continuous adjustment of the optics, also due to mechanical tolerances, can cause image jitter, which can be very disturbing. To avoid continuous adjustment, it is proposed to introduce hysteresis: For this purpose, it can be provided that, in order to avoid image jitter of the at least one image acquired by the visualization system, the at least one stabilization control loop is designed to have artificial hysteresis. This artificial hysteresis can preferably be implemented electronically. This results in the advantage of a significantly improved operating characteristic for the user of the visualization system (for example for the surgeon performing a medical operation), since image jitter is avoided.

[0018] Then the regulation implemented by the stabilization control loop can be designed such that the regulation only intervenes when the numerical change in the current temperature change detected with reference to the detected probe temperature is above a threshold. If the stabilization system detects a temperature change above this threshold, then the state of the optical system can be actively readjusted, for example, by driving the corresponding stepper motor in order to adjust the zoom optical device and / or the focusing optical device accordingly. In contrast, if only a numerical temperature change below this threshold is detected, then the regulation does not intervene.

[0019] For example, the hysteresis can be configured such that in the case of detecting a small, short-term temperature increase of, for example, 20 °C to 21 °C, the regulation of the focusing optical device and / or the zoom optical device is not yet carried out. On the other hand, the stabilization system can intervene via the at least one stabilization control loop, for example, in the case of the temperature increasing from 20 °C to 22 °C, thereby actively adjusting the focusing optical device and / or the zoom optical device and possibly then (in this example) cooling down to 21 °C again. The hysteresis can thus be set or determined, for example, with respect to the respective lens position. This results in: the visualization system may still be in different system states (with respect to the current focal length of the focusing optical device and the current zoom level) at the same temperature. Because depending on whether the temperature approaches 21 °C starting from 22 °C or starting from 20 °C (as in the above example), different finally adjusted states of the optical system can be caused. Instead of manual hysteresis, fixed predefined temperature thresholds can also be set, where once one of these temperature thresholds is reached (i.e., the detected temperature reaches this value), then the stabilization system intervenes. This can be implemented, for example, such that an active readjustment occurs once at the attainment of a specific temperature (for example: 20 °C, 23 °C, 26 °C).

[0020] However, the present invention has recognized that the magnitude of the hysteresis should be limited for two reasons:

[0021] On the one hand, if the surgeon sets a high zoom factor, the so-called depth of field (DOF) can only be a few millimeters, i.e., for example, + / - 1.5 millimeters. In this case, once the current position of the focal plane has changed significantly due to temperature compared to the current DOF, i.e., for example, by 1.0 millimeter, the stabilization system must already intervene. Because if the stabilization system only intervenes, for example, when the position of the focal plane has changed by 2 millimeters, then, for example, the current real-time image seen by the surgeon will become unclear because the temperature stabilization did not intervene in a timely manner. This is considered to be unconditionally to be avoided. It can also be stipulated that the hysteresis is automatically adjusted by the stabilization system according to the currently selected zoom and / or according to the working state or according to the current position of the focal plane.

[0022] However, on the other hand, there are also situations such as the following, where a particularly large working distance from the observed object is selected and a particularly small zoom level is set, resulting in a particularly large field of view. If, in such a situation, the world coordinates of an object in the real-time image of the camera are now to be determined using the described triangulation scheme, this is particularly error-prone with respect to temperature-induced fluctuations in the focal length of the focusing optics and the optical zoom level. In this application, that is, an absolute accuracy of ideally 50 μm but at least 100 - 300 μm should be achieved with respect to the location resolution when determining the world coordinates of the object. In order to achieve such accuracy when determining the position of the object in space, it is necessary that temperature stabilization intervenes early on in order to keep the temperature-induced deviations as small as possible.

[0023] Preferably, artificial hysteresis is implemented electronically. This can ensure, for example, that the minimum adjustment path is followed respectively when adjusting the corresponding focusing optics / zoom optics, which is advantageous in order to achieve high precision during adjustment. Preferably, a stepper motor is used for this purpose, which has the advantage of very high repeat accuracy with respect to the position to be reached.

[0024] In particular, the at least one stabilization control loop - which is designed with artificial hysteresis - can automatically initiate different adjustments to the focusing optics and / or the zoom optics based on the current state of the optical system and / or based on the detected current direction of temperature change.

[0025] The surgeon thus does not have to adjust the state of the optical system himself again. Preferably, these different adjustments are also automatically initiated independently of whether a new target value for adjusting the focusing optics and / or the zoom optics has been pre-given exactly from outside the at least one stabilization control loop (for example by the surgeon).

[0026] It can be stipulated that at least one detection temperature is directly sensed by means of a temperature sensor. One temperature sensor or multiple temperature sensors can be designed here, for example, as thermocouples (for example by means of thin metal wires on a membrane) or as thermistors. In addition, for example, parasitic temperature sensors can also be read, which are already present in the microcontroller or the corresponding image sensor anyway. It is also possible to average the values of multiple temperature sensors or combine them according to calculation rules in order to achieve higher stability of the adjustment. This can be advantageous, so that when only local temperature changes are restricted (which would only result in a small temperature-induced shift of the optics), no (excessive) active readjustment has already been initiated.

[0027] Alternatively or additionally, it may be provided that at least one detection temperature is detected indirectly. The indirect detection of the detection temperature can be achieved, for example, by a calculation based on the current electrical power loss of the electronic components of the visualization system. Additionally or alternatively, the electronic activity level of the electrical components can also be taken into account for the indirect detection of the detection temperature.

[0028] The corresponding detection temperature is preferably additionally detected continuously by the stabilization system as the corresponding current temperature. Additionally, the mentioned current temperature change (based on the correspondingly detected detection temperature) can be determined relative to the stored reference temperature. The reference temperature can preferably be adapted / updated by the stabilization system once the stabilization system, more precisely a stabilization control loop, intervenes in a closed-loop / open-loop manner. In particular, the state of the optical system can thus be actively matched to the new reference temperature, so that the state of the optical system also remains stable at this new reference temperature (i.e., even if the temperature changes within the imaging system, it does not cause a change in the focal plane or zoom level that is perceptible to the surgeon).

[0029] In the method, it can also be provided that the temperature-induced change in the spatial position of at least one component of the imaging optics (such as a movable lens) is detected sensorially. For this purpose, the visualization system can include a position sensor by which such a position change can be detected sensorially. Such a temperature-induced movement within the optomechanical imaging system can thus also initiate a temperature regulation algorithm that stabilizes the state of the optical system. Because the detection temperature can also be detected at least indirectly via such a position change.

[0030] Therefore, in other words, it can be provided that once at least one position threshold for the at least one sensorially detected temperature-induced position change is exceeded, the focusing optics and / or the zoom optics are actively adjusted by the at least one stabilization control loop. By temperature-induced, it can be understood here that the spatial position of the component changes unintentionally based on a temperature change, in particular a temperature change exceeding a determined threshold.

[0031] In another advantageous design of the invention, it can be provided that the corresponding adjustment of the focusing optics and / or the zoom optics is not carried out as early according to the current state of the optical system, in particular according to the current adjustment of the focusing optics and the currently set zoom level, with reference to the detected at least one current temperature change. Depending on which optical system state the imaging optics is exactly in, the stabilization system will intervene in a closed-loop manner at different magnitudes of temperature change in order to stabilize the current state of the optical system. This can prevent, for example, that in the first system state, frequent but actually unnecessarily early adjustments of the optics occur, while in the second system state, the adjustment does not occur early enough.

[0032] In particular, the at least one temperature threshold can be adjusted according to the current state of the optical system, so that the temperature stabilization intervenes when there is a small temperature change in the detected temperature according to the current state of the optical system or only when there is a larger temperature change.

[0033] In an advantageous design of the present invention, it can be provided that the at least one stabilization control loop also operates when no new optical system state is pre-given by the visualization system itself or by the user as a specified target. In particular, this enables the continuously set optical system state to be stabilized relative to temperature fluctuations by the stabilization system (active autonomous regulation implemented by the stabilization system).

[0034] Therefore, the optical system state can be continuously stabilized by the stabilization system, more precisely, the user does not perceive the open-loop control intervention of the stabilization system in the real-time image recorded by the at least one image sensor. The user of the visualization system, such as a surgeon, can thus use the visualization system without interference.

[0035] In another advantageous design of the present invention, it can be provided that in the case of exceeding the at least one temperature threshold and / or the at least one position threshold, the at least one stabilization control loop drives at least one actuator of the focusing optical device and / or the zoom optical device. Thereby, a corresponding early active readjustment of the zoom optical device and / or the focusing optical device can be generated.

[0036] In particular, the actuator can be a stepper motor.

[0037] The at least one stabilization control loop can drive the corresponding actuator in particular via a separate corresponding control loop. Then, the actuator can be regulated in a closed-loop manner by means of the separate control loop.

[0038] In a preferred design of the visualization system, it is provided that the stabilization system (for example, via a corresponding stabilization control loop) drives at least two actuators of the zoom optical device, in particular at least two stepper motors, and at least one actuator of the focusing optical device. For example, the stabilization system can intervene in an open-loop manner into at least two separate control loops for adjusting the zoom optical device and at least one further control loop of the focusing optical device, so as to adjust the corresponding actuators closed-loop controlled by the corresponding control loops in such a way that the detected temperature change, which causes a change in the system state, can be compensated. One of the control loops of the stabilization system can also act on the two actuators of the zoom optical device in an open-loop manner at the same time, for example, in the case where the zoom optical device is constructed by two movable lens pairs that can move towards or away from each other.

[0039] As described above, one, in particular a corresponding (sub) stabilization control loop, as part of a superior stabilization system, can also drive multiple actuators, where these actuators can also be assigned to the same optical function: Thus, a zoom optical device can include, for example, two optically movable lens groups relative to each other. In such a case, both of these lens groups can be driven by corresponding assigned stabilization control loops to compensate for temperature effects.

[0040] Here, different adjustment paths A and B (for a current optical system state) can be stored for each of the two lens groups respectively (i.e., for example: zoom group 1: A µm / K, zoom group 2: B µm / K). Additionally, it can be advantageous that the respective actuators (as already described above) can be acted upon by different sub-stabilization control loops, i.e., can be driven by multiple different sub-stabilization control loops of the superior stabilization control loop. Such an adjustment architecture can be understood in the sense of the present invention as a single large overall stabilization control loop, the individual sub-control loops of which can compensate for different temperature-induced interference parameters in order to thereby stabilize the optical system state as desired with respect to temperature changes. Thus, for example, one of the respective stabilization control loops - which in particular should stabilize the focusing optical device - can also be arranged to additionally drive the zoom optical device. Conversely, a stabilization control loop - which in particular should stabilize the zoom optical device - can also be arranged to additionally drive the focusing optical device.

[0041] In particular, the respective actuators can be driven to adjust the focusing optical device and / or the zoom optical device along the optical z-axis of the imaging optical device. It can be provided here that the at least one stabilization control loop drives the respective actuators mediated by a separate corresponding control loop, by means of which the actuator can be regulated in a closed-loop manner.

[0042] The stabilization control loop, in particular the corresponding sub-control loop, can also be designed such that multiple control loops act on one actuator simultaneously. For example, the visualization system can be designed parfocally so that the focus does not change with zoom. In such a design, it may be necessary for the sub-control loop that adjusts the zoom of the stabilization control loop to also act on the actuator for the focus, so that this control loop can cause simultaneous adjustment of the focusing optics and the zoom optics. This may be necessary, for example, in the case where the focus has changed due to tolerances or other artifacts, although the system was originally designed parfocally. The control loop responsible for zoom can also act on the focus actuator in such a way that, although the second sub-control loop responsible for the focus does not recognize the cause for changing the focus, for example because the detected temperature change in the focus part is still below a specific threshold.

[0043] In an advantageous design of the present invention, it can be provided that once the at least one current temperature change detected for the temperature exceeds the assigned temperature threshold still allowed for the current optical system state, the stabilization system adjusts the focusing optics and / or the zoom optics in an open-loop manner. Preferably, this is carried out independently of the corresponding target values previously set by the user or by the visualization system for the adjustment of the focusing optics and / or for the adjustment of the zoom optics.

[0044] In particular, no target actual values for the corresponding adjustment parameters of the focusing optics and / or the zoom optics, such as the last pre-given focal length or the last pre-given optical zoom level, occur. As a result, the stabilization system can thus also intervene in a stabilizing manner with respect to the optical system state in the case where exactly no new instructions for the adjustment of the focusing optics and / or for the adjustment of the zoom optics are output by the user or by the visualization system.

[0045] In an advantageous variant of the method, it can be provided that the stabilization system adjusts the focusing optics and / or the zoom optics in an open-loop manner based on a corresponding temperature model. Here, the stabilization system can in particular deviate from the respective target value pre-given last (by the user or by the system itself) in order to stabilize the current optical system state with respect to the detected at least one current temperature change. The corresponding temperature model can here model the necessary temperature-dependent adjustment of the focusing optics (for example ΔFL(T, ΔT, FL, ZL)) or the zoom optics (for example ΔZL(T, ΔT, FL, ZL)), for example as a function of the current detected temperature T, the detected change ΔT of the detected temperature (where it can be taken into account whether the change ΔT is positive or negative), the current focal length FL, and / or the current zoom level ZL. It should be mentioned here that the magnitude of the focal length FL determines the spatial position of the resulting focal plane (i.e., the plane that is imaged sharply onto the image sensor) along the optical axis. In order for the surgeon to obtain a clear image, the focal plane must therefore coincide with the observed area.

[0046] Therefore, preferably, the temperature model here takes into account the current optical system state (FL, ZL), in particular the current focal length FL of the focusing optics and / or the current zoom level ZL of the zoom optics.

[0047] Another advantageous design of the invention provides that the stabilization system - preferably based on the previously described temperature model or another temperature model - calculates a suitable compensatory adjustment for the zoom optics and / or the focusing optics, in particular a corresponding suitable adjustment path Δz along an optical z-axis or the previously described optical z-axis, based on the detected at least one current temperature change. Thereby, for example, a suitable adjustment path Δz can be determined for any detected temperature change, along which the focusing optics and / or the zoom optics must be actively readjusted accordingly.

[0048] From the calculated adjustment, the stabilization system can regenerate the corresponding drive signals for adjusting the zoom optics and / or the focusing optics (in particular by intervening in the respective individual adjustment loops). In this way, the current optical system state can be stabilized in a temperature-dependent manner.

[0049] In another advantageous design, it can be provided in the method that the stabilization system takes into account the detected value of the current detected temperature T and adjusts the at least one temperature threshold ΔT max(T), the stabilization system intervenes in an open-loop control from the at least one temperature threshold value (for example as a result of the adjustment of the reference temperature). This adjustment is preferably carried out after the stabilization system has intervened in an open-loop control. The temperature-induced adjustment of the temperature threshold value and / or the reference temperature mainly enables the stabilization system to intervene sometimes early and sometimes late, depending on the current position of the detected temperature, depending on the required situation. The regulation is therefore adaptive here, depending on the temperature actually existing in the detection area. In particular, the corresponding temperature model (ΔFL (T, ΔT, FL, ZL), ΔZL (T, ΔT, FL, ZL)) can be adjusted accordingly according to the detected value of the detected temperature T. Therefore, different control signals can be generated by the corresponding stabilization control loop according to the currently detected detection temperature even in the case of a relative temperature change ΔT of the same size (relative to the currently stored reference temperature).

[0050] The claimed method can furthermore include the detection of a current change ΔT in the detection temperature in at least two spatially different detection regions, preferably within the imaging optics. This results in the advantage that the probability of detecting a current change in the detection temperature as early as possible can be increased, so that readjustment can be made as early as possible. If, for example, a change in the detection temperature is only ascertained in one spatial detection region, there is the risk that (for example due to thermal inertia) the temperature change in the spatial detection region in which the actual cause of the heating is located cannot be detected accurately or early enough, and that the focusing optics and / or zoom optics can then be readjusted too late. Preferably, the respective current detection temperature T is additionally detected in at least two spatially different detection regions.

[0051] Additionally or alternatively, it can be provided that the at least one current temperature change ΔT is used as an input variable of the at least one stabilization control loop, so that the stabilization control loop, in particular a corresponding stabilization control loop, of the stabilization system is triggered by, in particular only by, the temperature change. It can thus be largely excluded that other non-thermal influencing factors lead to undesired active adjustments of the zoom and / or focus optics. In particular, the stabilization control loop, in particular a corresponding stabilization control loop, is then not triggered by a change in the current target value for the optical system state.

[0052] As already mentioned, the respective temperature threshold value, based on which the respective stabilization control loop of the stabilization system intervenes in an open-loop manner, can be dependent on the state of the optical system and / or at least one (ie, in particular, a plurality of) associated current detection temperatures, which are measured in the detection region. As a result, the stabilization system can intervene in an open-loop manner sometimes more intensively / early and sometimes less intensively / early, depending on the requirements:

[0053] For example, a small depth of field (small DOF) can be generated when setting a high zoom factor. In this case, once the current position of the focal plane has changed significantly due to temperature compared to the current DOF, i.e., for example, by 1.0 mm, the adjustment must have intervened. Because if the adjustment only intervenes when the position of the focal plane changes by 2 mm, for example, the current real-time image seen by the surgeon will become unclear because the temperature stabilization does not intervene in time. This is considered to be unconditionally to be avoided.

[0054] In contrast, in the case of a large working distance and a small zoom level, a large field of view and a relatively large depth of field are generated. Therefore, it can be meaningful that a small temperature-induced drift of the focal plane is not immediately compensated by the stabilization system by an early adjustment of the focal length.

[0055] In contrast, if the world coordinates of an object in the camera real-time image are determined using the described triangulation scheme in such a case (for example, for the purpose of navigation or measurement functions), this is particularly error-prone with respect to the temperature-induced fluctuations of the focal length of the focusing optics and the optical zoom level. In such a case, it can therefore be advantageous to reduce the at least one temperature threshold since which the stabilization system initiates the adjustment of the imaging optics.

[0056] In other words, it can then be stipulated that the at least one temperature threshold is adjusted according to the current operating mode of the visualization system (navigation / measurement / real-time video imaging in the case of a large working distance and a small zoom level).

[0057] If the visualization system is designed, for example, to be parfocal, the zoom optics and the focusing optics can be adjusted independently of each other. In such a case, the temperature drift acting on the imaging optics always has the same effect, regardless of the zoom level exactly selected. Thus, if active adjustment (readjustment) of the focusing optics is necessary at a high zoom level, this temperature stabilization / compensation will also be necessary at a low zoom level. However, with regard to navigation implemented with the visualization system, this means that, in the case of initially setting a high zoom level, once the zoom level is reduced, the absolute error in position determination automatically increases (for example, from initially 1.5 mm to finally 20 mm). Thus, compared to the case of a high zoom level, in the case of a low zoom level, the temperature-induced drift of the focusing optics more strongly affects the determined absolute position. With regard to the desired temperature stabilization, this means that the temperature-induced path drift of the focal plane is more of a problem in the case of a high zoom level; while in the case of a low zoom level, if the visualization system is used (especially automatically) to navigate or measure a path in the field of view, the loss of accuracy is more of a problem. However, the adjustment paths required for temperature stabilization of the focusing optics respectively are the same in both cases in the parfocal design of the visualization system (i.e., independent of the current zoom level).

[0058] In one design variant, it can be provided that the current optical system state is stabilized only indirectly by adjusting the at least one temperature threshold. This adjustment can be made, for example, due to an externally initiated change in the system state. Thus, the stabilization system changes by itself and autonomously, and the adjustment is matched to the changed system state. The externally initiated change in the system state can here be, for example, a desired change in the focusing optics and / or the zoom optics.

[0059] Additionally or alternatively, it can be provided that the current optical system state is stabilized by actively adjusting the current settings of the focusing optics and / or the zoom optics, in particular due to detecting an exceedance of the at least one temperature threshold.

[0060] In both cases, it can then occur that the stabilization system intervenes because the at least one temperature threshold ΔT(T) is temperature-dependent (and is exactly adjusted by the stabilization system) and the currently detected temperature T has changed, such that the previously detected current temperature change now exceeds the adjusted temperature threshold ΔT(T).

[0061] To solve the object mentioned at the beginning, the present invention proposes features of the claims directed to the visualization system in parallel. In particular, in a visualization system of the type described at the beginning, according to the present invention, the imaging optics are arranged in a dust-proof housing, and the at least one detection area is located within the housing. Thereby, the following advantages can be achieved: The temperature detector is arranged close to the source causing the temperature rise, thereby enabling rapid detection of the temperature rise. Here, it is particularly preferred that the at least one temperature detector is arranged adjacent to the focusing optics.

[0062] The dust-proof property of the housing furthermore allows the housing to be cleaned from the outside with a disinfection mechanism, while liquid cannot enter the interior of the visualization system. In particular, it can be provided that the housing is airtight and / or metallic.

[0063] The at least one temperature detector can, for example, directly and sensorially detect the at least one current temperature change (which is generated in the housing, for example, due to electrical power loss). Furthermore, it can be provided additionally or alternatively that the heat generated in the housing (for example, due to electrical power loss) can be detected by the temperature detector at least indirectly or directly.

[0064] The temperature detector in the sense of the present invention can hereby be understood not only as a general temperature sensor, but also as a parasitic temperature sensor - as is often already implemented in electronic components - or also as the following (preferably electronic) detector, which, based on the information called up (for example, the current activity level of an electronic component such as an image sensor or an actuator or an IC (integrated circuit)), estimates the temperature change, for example, by means of calculation, and thereby enables the temperature change to be detected indirectly.

[0065] Additionally, according to the present invention, it is provided that the visualization system includes a stabilization system with at least one stabilization control loop, such that the stabilization system can actively stabilize the current optical system state of the visualization system based on the measured and / or indirectly detected at least one current temperature change. Thereby, for example, it can be prevented that the focusing optics and / or the zoom optics are excessively displaced due to thermally induced effects (which would adversely affect the operation of the system).

[0066] Preferably, the visualization system, in particular its stabilization system, is arranged to perform the method according to the present invention, in particular as described above and / or as claimed.

[0067] In the claimed visualization system, furthermore, it can be advantageously provided that the at least one temperature detector is arranged adjacent to the optical lens of the imaging optics within the housing, for example, on the lens mount.

[0068] Alternatively or additionally, it can be provided that the at least one temperature detector is arranged at at least one position within the housing at which the thermal expansion of the opto-mechanical components of the imaging optical device (which is determined empirically and / or simulated, in particular by means of "finite element method (FEM)", as calculated) significantly influences the position and / or orientation of the focusing optical device, more precisely the position and / or orientation with respect to the optical z-axis of the imaging optical device. Since precisely these points are particularly critical with regard to the stabilization of the optical system state, the stabilization system can intervene in a closed-loop control manner early enough if significant temperature changes occur at these positions.

[0069] Alternatively or additionally, the at least one temperature detector can be arranged at at least one position within the housing at which the thermal expansion of the opto-mechanical components of the imaging optical device significantly influences the orientation of the zoom optical device with respect to the optical z-axis of the imaging optical device.

[0070] In a further advantageous design of the invention, it can be provided that the visualization system comprises at least one stepper motor which is configured to adjust the focusing optical device and / or the zoom optical device (in particular via a mechanical spindle). Thus, for example, the current focal length of the focusing optical device and / or the zoom optical device can be actively readjusted as necessary by means of the detected temperature changes, more preferably in such a way that the user of the visualization system does not perceive any noticeable changes in the real-time video image.

[0071] Preferably, at least two stepper motors are designed for adjusting the zoom optical device and at least one stepper motor is designed for adjusting the focusing optical device.

[0072] For example, it can be provided that a classical lens made of glass is moved along the optical z-axis or an optical z-axis by means of a corresponding stepper motor. The stepper motor drives the mechanical spindle here, and the inevitable mechanical play still allows tolerances of a few micrometers, so that an accuracy of a few micrometers can be achieved when adjusting the corresponding lens along the z-axis.

[0073] In particular, each of the stepper motors can be coupled (in particular via its own control loop) to the at least one stabilization control loop, in particular the corresponding stabilization control loop, so that the stabilization system can drive the corresponding stepper motor in an open-loop control manner.

[0074] In an advantageous embodiment of the visualization system, it can be provided that the visualization system has at least one control unit for actuating and thus adjusting the focusing optics and / or the zoom optics (in particular by means of at least one stepper motor). Here, the stabilization system is provided for stabilizing the current optical system state by means of the control unit. Thus, an adjustment loop for temperature stabilization of the optical system state is produced (however, not for temperature regulation).

[0075] Preferably, even if neither the user nor the visualization system itself is pursuing a change in the system state or is predefining a change in the system state with a new target for the system state, the stabilization system stabilizes the optical system state by means of the control unit.

[0076] Advantageously, it can be provided in an embodiment of the visualization system that an artificial, preferably electronically implemented hysteresis is designed in the stabilization system, in particular as detailed previously. By providing artificial / electronic hysteresis, it is possible to ensure, as already mentioned, in particular that a minimum adjustment path is followed when adjusting the respective focusing optics / zoom optics, which is advantageous in order to achieve high precision during adjustment, especially in the case of using stepper motors. The artificial hysteresis can be designed here in particular based on at least one (preferably variable) temperature threshold.

[0077] Preferably, the artificial hysteresis is designed in the stabilization system such that the intervention of the stabilization system in the case of temperature changes (which stabilizes the current optical system state) is carried out in such a way as to avoid perceptible image jitter of the images acquired by the visualization system for the user. This results in significantly improved operating characteristics of the visualization system for the user, such as a surgeon. The images acquired by the visualization system can be, for example, real-time video images, for example within the scope of a stereoscopic observation method.

[0078] Additionally or alternatively, in a visualization system of the type described at the beginning, in particular in the visualization systems already claimed or mentioned, the features of claim 18 are provided in parallel. In particular, for this purpose, according to the invention, it is proposed that the visualization system, in particular the stabilization system of the visualization system, is set up to carry out the method already mentioned or claimed. Thus, the already mentioned advantages of the method can be advantageously achieved.

[0079] The invention will now be further described with the aid of various embodiments, but the invention is not limited to these embodiments. Further improvements of the invention can be obtained from the following description of the preferred embodiments in combination with the general description, the claims and the drawings. Description of the Drawings

[0080] In the following description of different preferred embodiments of the present invention, elements that are functionally consistent with each other also receive consistent reference numerals in the case of different configurations or shapes. In the figures:

[0081] Figure 1 shows a schematic view of a visualization system according to the present invention;

[0082] Figure 2 shows the time curve of the detected temperature, which is automatically detected inside the housing of the imaging optics of the Figure 1 visualization system;

[0083] Figure 3 shows Figure 1 a schematic view of the stabilization adjustment loop of the stabilization system of the visualization system of

[0084] Figure 4 shows Figure 1 the schematic system architecture of the stabilization system of the visualization system of

[0085] Figure 5 and finally Figure 1 shows a typical application scenario in which the visualization system according to the present invention can be applied.

[0086] Figure 1 shows a visualization system 1 according to the present invention, which is formed as part of a robotic system 26 as shown in Figure 5 and with which a neurosurgical operation can be performed. The entire visualization system 1 - which includes the components described in claim 13 - is hereby assembled on the movable arm of the robotic system 26 and can thus be placed at different working distances relative to the patient's head and thus relative to the surgical area 8. Here, the surgeon can observe on the display screen 46 as a real-time image the images recorded by the image sensor 6 of the visualization system 1.

[0087] In order to be able to generate different views of the surgical area 8 during the surgical operation, the visualization system 1 has: an adjustable zoom optics 3 with which the current optical zoom level 17 can be set; and an adjustable focusing optics 4 with which the focusing optics can determine on which current focal plane 5 the imaging optics 2 is focused, for which see the structure of the imaging optics 2 according to Figure 1 The focusing optics 4 hereby includes two optical lenses 29, one of which - which serves as a focusing lens 36 - can be moved along the optical z-axis by means of the shown stepping motor 20 in order to thereby adjust the focal length 23.

[0088] The zoom optics 3 includes two zoom structural components, each of which includes a plurality of optical lenses 29 and can be adjusted respectively by actuators 19 in the form of respective associated stepping motors 20.

[0089] Furthermore, it can be seen in Figure 1 that the imaging optics 2 is designed for stereoscopic observation and has two parallel optical channels 47a and 47b, which end in respective image sensors 6a and 6b. The two optical channels jointly utilize the focusing optics 4 here, while adjustable zoom optics 3 are respectively designed in the respective channels 47a / 47b and are adjustable respectively independently of one another by means of two respectively associated actuators 19. The respective individual images generated by these two image sensors 6a and 6b can be used here to generate a stereoscopic observation view of the surgical area 8. Between the respective image sensors 6a / 6b and the respective zoom optics 3, here in each of the two optical channels 47a and 47b, an objective lens 33 / 34 is provided. The actuator 19 for adjusting the lower zoom optics 3 of the second optical channel 47b is not shown in Figure 1 for the sake of clarity.

[0090] Each of the optical channels 47a and 47b has a respective temperature detector 27 here, which is arranged at different positions within the housing 28, which encloses the imaging optics 2 overall dust-tight. In the example of Figure 1 , these temperature detectors 27 are designed in the form of respective temperature sensors 15, which can directly and sensorially measure the respective detection temperature 12 within the respective detection area 13. However, alternatively, it is also possible, for example, to detect only some of these detection temperatures 12 indirectly, i.e., non-sensorially. For this purpose, the respective temperature detector 27 can be arranged, for example, to estimate a change in the local detection temperature 12, for example, based on the detected active level of an electronic component generating heat loss power, in order to indirectly detect the temperature change thereby. The temperature detectors 27 arranged at different positions within the imaging optics 2 and the respective detection areas 13 detected by them are shown here in Figure 1 as dashed ellipses, where the temperature detectors 27 are naturally not placed in the respective imaging light paths in order not to interfere with the respective optical imaging. But all of these detection areas 13 are located within the housing 28 (shown as dashed lines in Figure 1 ), which isolates the imaging optics 2 from the outside world.

[0091] As already mentioned at the beginning, significant temperature changes can occur for different reasons, which during the use of the visualization system 1 (see Figure 5This results in the current state of the optical system - which includes the current optical zoom level 17 and the current spatial position of the focal plane determined by means of the focusing optics 4 (where the respective optical zoom level 17 can even deviate slightly between the two optical channels 47a and 47b) - changing in an undesirable way. For example, it may happen that the position of the current focal plane is displaced due to thermal drift in the imaging optics 2 in such a way that the surgeon no longer obtains a clear image of the surgical area 8, which can be very disturbing. In order to prevent such a situation prophylactically and in particular to enable the neurosurgeon to concentrate on the actual surgery and not have to manually adjust the visualization system 1 himself, the latter has a stabilization system 9, which can actively stabilize such temperature-induced fluctuations in the state of the optical system by means of a stabilization control loop 10. Here, the stabilization system 9 continuously detects the respective detection temperature 12 (directly or at least indirectly).

[0092] In Figure 1 the system 1 shown here has a plurality of such stabilization control loops 10, where Figure 3 one of these control loops 10 is shown exemplarily: Starting from the current temperature 25 (which is continuously detected as the detection temperature 12 by one of the temperature detectors 27 in the detection area 13 monitored by the temperature detectors 27), the comparator 41 compares this current measured value with the current reference temperature 40 (= the value stored / saved currently, which serves as the reference point for the control loop). By means of this comparison, the stabilization system 9 thus detects the current temperature change 11 relative to the current reference temperature 40 and, therefrom, calculates in a calculation step 42 new positions for the focusing optics 4 and the zoom optics 3 of the optical channels 47a / 47b (in which the temperature detectors 27 are arranged).

[0093] If, for example, a significant temperature change 11 relative to the current reference temperature 40 is detected in the area of the jointly used focusing optics 4, then the stabilization system 9 can not only intervene in a closed-loop control manner (regelnd) (eingreifen) on the focusing optics 4 and actively adjust the focusing optics accordingly, but can also act on the two zoom optics 3 of the two optical channels 47a, 47b in a supplementary open-loop control manner (steuernd) (only one such path is shown for one lens 29 in Figure 3 ). In the example shown in Figure 3 , the stabilization system 9, more precisely the shown stabilization control loop 10, thus causes a corresponding change 43 in the position or setting of the focusing optics 4 and / or the zoom optics 3.

[0094] Here, the stabilization system 9 calculates the exact magnitude and direction of the respective active adjustment to be made to the focusing optics 4 and / or the zoom optics 3 according to the corresponding temperature model. The corresponding temperature model for determining the required active adjustment (e.g., ΔFL(T, ΔT, FL, ZL)) describes here the temperature characteristics of the respective optics 3 / 4, more precisely according to the exactly adopted reference temperature 40 (=T), the detected temperature change 11 (=ΔT), and the currently set zoom level (ZL) and the focal length (FL) of the focusing optics 4 (which gives the current position of the focal plane).

[0095] Therefore, in step 43, the focusing optics 4 and / or the zoom optics 3 are actively adjusted by the stabilization control loop 10. Naturally, steps 42 and 43 only occur if the previously detected current temperature change 11 has actually exceeded the current temperature threshold 18.

[0096] Since the probe temperature 12 is continuously detected, the reference temperature 40 is also updated in step 44 (dashed arrow), which can be achieved, for example, by measurement 48 or alternatively by means of an updated estimate of the probe temperature 12. As a reference, in particular, the temperature detected at the moment of actively adjusting the imaging optics 2 can be applied: If, for example, a temperature of 25 °C is detected, which is already above the threshold 18 of 24 °C, and subsequently the active adjustment of the imaging optics 2 is carried out, then the new reference value can be adjusted to 25 °C. In other words, preferably, the reference temperature 40 of the specific probe temperature 12 for the specific probe area 13 is updated whenever the associated stabilization control loop 10 / stabilization system 9 intervenes in an open-loop manner on the imaging optics 2.

[0097] The reference temperature 40 can be determined, for example, according to a calculation rule based on the temperature detected at the moment of compensation. But it can also be determined, for example, that an adjustment is made when a certain first temperature threshold is exceeded (e.g., T = 23 °C) and the next adjustment is only made when a certain second temperature threshold is also exceeded (e.g., T = 26 °C).

[0098] Therefore, temperature stabilization in the sense of the present invention can in principle be achieved in two ways:

[0099] A) The at least one temperature threshold remains unchanged. If, in such a case, an adjustment is carried out, for example, due to exceeding the first temperature threshold of 23.0 °C and subsequently a temperature of 25.80 °C is measured, then the adjustment is only carried out again when the temperature further increases and the second temperature threshold of 26 °C is reached. Therefore, this scenario A) provides immutable thresholds, so that the stabilization system always intervenes at the same temperature.

[0100] B) However, it is also possible to shift the reference temperature, for example by means of temperature increments (see: Figure 2 ), in other words, the imaging optics are regulated in accordance with the currently measured temperature of, for example, 25.8°C, and the temperature thresholds are shifted upward by a fixed value, for example, 1.5°C, i.e., for example, to 27.3°C as an upper threshold and 24.3°C as a lower threshold. This variant B) therefore provides for active thresholds to be carried over as long as the stabilization system intervenes in a closed-loop controlled manner, so that the temperature (from which the stabilization system intervenes) can be continuously varied. The value of the corresponding temperature threshold shift can be derived from at least one temperature currently detected by the stabilization system 9.

[0101] In addition Figure 3 It can be seen that the stabilization control loop generates a corresponding control signal 49, which is used to adjust the zoom optical device 3 and / or the focusing optical device 4 (in Figure 3 In the example shown, only one of these signals 49 is shown by way of example. In the example shown, the stabilization system 9, more precisely the stabilization control loop 10 shown, intervenes in a separate control loop 22, which controls one of the lens actuators 19 in order to thereby move the lens 29 by a certain distance Δz1.

[0102] In this way, the stabilization control loop 10 can, in step 43, for example, pass control parameters 50 for adjusting the corresponding lens position to a suitable control loop 22, so that the actuator 19 then causes a corresponding adjustment of the lens 29. This can indeed occur noticeably if neither the visualization system 1 nor the user predetermines a new visual system state as a predetermined target. Of course, even if neither the robot system 26 nor the user wants to set a different focal plane, the stabilization system 9 can still respond autonomously to the detected current temperature change 11 and actively adjust the focusing optics 4, in particular taking into account the current optical system state, in order to preventively suppress temperature-induced drifts of the optical system state. The imaging is thus actively stabilized, so that the surgeon can concentrate on the surgical operation.

[0103] The challenge in such a control concept is that the operating surgeon does not feel disturbed by the fact that the stabilization system 9 continuously and thus disturbingly adjusts the zoom optics 3 and / or the focus optics 4. For this reason, the stabilization control loop 10 is equipped with an artificial hysteresis, so that the visualization system 1 can be in different optical system states at the same temperature, depending on how the currently detected detection temperature 12 was reached, i.e., for example, due to a temperature increase or a temperature drop.

[0104] This approach can be well suited, for example, to Figure 2Implementation: There, the time curve of the detected probe temperature 12 detected by means of the temperature sensor 15 of the visualization system 1 is visible. The stabilization system 9 here detects the current temperature change 11 at regular time intervals as the difference between the currently detected probe temperature 12 and the currently stored reference temperature 40. As long as the continuously detected temperature change 11 ΔT remains within the boundaries determined by the two temperature thresholds 38, 39, the stabilization system 9 does not intervene.

[0105] However, after the upper temperature threshold 38 has been exceeded at time t1, the stabilization system 9 thus intervenes in a stabilizing manner to unchangedly change the state of the optical system that was previously changed due to the occurring temperature change 11, such that the state of the optical system is stabilized again. The adjustment of the focusing optics 4 and / or the zoom optics 3 caused by the intervention of the stabilization system 9 is shown here by the changing hatching in Figure 2 In the present invention, exceeding the temperature threshold 18 is understood here as exceeding the corresponding temperature boundary 38 / 39: This can occur in the positive or negative direction, as can be well understood according to Figure 2 As can be understood. According to the design, the temperature thresholds 38, 39 can also be at different distances from the reference temperature 40 (= asymmetric temperature interval).

[0106] It can be seen here that the stabilization control loop 10 has a hysteresis 14. If two times A and C are compared with each other: Although the same probe temperature 12 exists / is detected at these two times, the two optical devices 3 and 4 are in different settings, because in other words, point A is reached within the two boundaries 38 and 39 by a slight temperature increase, while point C is reached after the temperature has dropped and after the upper temperature threshold 38 has been exceeded starting from time B.

[0107] In contrast, at time t2, the currently detected probe temperature 12 is again below the lower temperature threshold 39, and subsequently the stabilization control loop 10 intervenes again in a closed-loop control manner in order to re-stabilize the state of the optical system. The resulting changed settings for the two optical elements 3 and 4 are again shown by different hatching. It is also visible that when the stabilization control loop 10 intervenes in a controlled manner / in a manner of adjusting the optical elements 3 and / or 4, the stored reference temperature 40 and the positions of the upper and lower temperature thresholds 38, 39 are always adjusted accordingly. Thus, the stabilization control loop 10 intervenes, for example, at time t2 already at a probe temperature 12 at which the stabilization control loop did not intervene during the time period t0 to t1. In other words, the temperature thresholds 38, 39 are thus selected here respectively according to the currently stored reference temperature 40. Here, the system can also match the size of the temperature interval (in which the stabilization control loop 10 does not yet intervene) defined by the two temperature thresholds 38, 39 according to the height of the currently stored reference temperature 40 (and thus determine an earlier or later intervention according to the application and / or the requirements of the applied imaging optical device 2).

[0108] Figure 4 Shows a possible implementation of the stabilization system 9 according to the invention: The stabilization system includes a control unit 31, which is implemented by means of a microcontroller 45, and the control unit / microcontroller is set for: calculating a new position of the focusing optical element 4 or the zoom optical element 3 according to a plurality of corresponding probe temperatures 12 detected by means of temperature sensors 15.1, 15.2 and 15.3 (calculation step 42). Here, the microcontroller 45 also takes into account the current temperature threshold 18. The current temperature threshold, like the corresponding current reference temperature 40, is also adjusted by the control unit 31 respectively according to the current state of the optical system and according to at least one of the three different probe temperatures 12.

[0109] The microcontroller 45 implements a plurality of stabilization control loops 10 here, which can be configured, for example, similar to Figure 3 the stabilization control loop. The control unit 31 / microcontroller 45 intervenes here respectively in an open-loop control manner in the corresponding individual control loops 22 by means of the corresponding drive signals 49 to operate the respectively assigned actuators 19 in the control loops. In this way, the control unit 31 can, as shown in Figure 1 , actively adjust the two structural components of the zoom optical element 3 and the common focusing optical element 4 when necessary and thus finally stabilize the zoom level 17 and the focal length 23 and thus the position of the focal plane.

[0110] In summary, to improve the operation of the visualization system 1 (which includes an imaging optics 2 with an adjustable zoom optics 3 and an also adjustable focusing optics 4), it is proposed to detect at least one detection temperature 12 directly or indirectly (e.g., by estimation) within the imaging optics 2 by means of at least one temperature detector 27, and as long as the currently detected temperature change 11 regarding the detection temperature 12 exceeds a temperature threshold 18, actively adjust the focusing optics 4 and / or the zoom optics 3 by means of a stabilization system 9 that includes one or more stabilization adjustment loops 10 (see Figure 1 ). List of reference numerals

[0111] 1 Visualization system

[0112] 2 Imaging optics

[0113] 3 Zoom optics

[0114] 4 Focusing optics

[0115] 5 Focal plane

[0116] 6 Image sensor

[0117] 7 Object being observed

[0118] 8 Surgical area

[0119] 9 Stabilization system

[0120] 10 Stabilization adjustment loop

[0121] 11 Temperature change

[0122] 12 Detection temperature

[0123] 13 Detection area

[0124] 14 Hysteresis

[0125] 15 Temperature sensor

[0126] 16 Electronic component

[0127] 17 Zoom level

[0128] 18 Temperature threshold

[0129] 19 Actuator

[0130] 20 Stepper motor

[0131] 21 Z-axis

[0132] 22 Adjustment loop

[0133] 23 Focal length

[0134] 24 Adjustment path

[0135] 25 Currently detected temperature

[0136] 26 Robot system

[0137] 27 Temperature detector

[0138] 28 Housing

[0139] 29 Lens

[0140] 30 Lens holder

[0141] 31 Control unit

[0142] 32 Thermistor

[0143] 33 Objective lens 1

[0144] 34 Objective lens 2

[0145] 35 Motor

[0146] 36 Focusing lens

[0147] 37 Time axis

[0148] 38 Upper temperature threshold

[0149] 39 Lower temperature threshold

[0150] 40 Reference temperature

[0151] 41 Comparator

[0152] 42 Calculate the new position of the focusing optical device / zoom optical device

[0153] 43 Change the position

[0154] 44 Update the detected detection temperature (as the current measurement value / as the reference temperature for the adjustment loop)

[0155] 45 Microcontroller

[0156] 46 Display screen

[0157] 47 Optical channel

[0158] 48 Measurement of 12

[0159] 49 Drive control signal

[0160] 50 Control parameter

[0161] 15.1 Temperature sensor 1

[0162] 15.2 Temperature sensor 2

[0163] 15.3 Temperature sensor 3

[0164] 19.1 Actuator 1

[0165] 19.2 Actuator 2

[0166] 19.3 Actuator 3

Claims

1. Method for temperature stabilization of a current optical system state of a visualization system (1), in particular a medical visualization system, comprising an imaging optical device (2), the imaging optical device comprising: - an adjustable zoom optic (3) for determining a current optical zoom level (17), and - an adjustable focusing optical device (4) for determining the current spatial position of the focal plane (5), and comprising: - at least one image sensor (6), - acquiring at least one image of an object (7), for example an operating area (8), observed by the visualization system (1) with the at least one image sensor (6), and - using the method to stabilize the current optical system state with respect to temperature-induced fluctuations in the imaging optical system (2), the current optical system state comprising the current optical zoom level (17) and the current spatial position of the focal plane, It is characterized in that - continuously, directly or indirectly detecting at least one current temperature change (11) of a detected temperature (12) in at least one detection area (13) in the visualization system (1) by means of a stabilization system (9) comprising at least one stabilization control loop (10), and - actively regulating the focusing optics (4) and / or the zoom optics (3) by the at least one stabilization control loop (10) as soon as at least one temperature threshold value (18) for the at least one current temperature change (11) is exceeded.

2. The method according to claim 1, wherein: In order to avoid image jitters in the at least one captured image, the at least one stabilization control loop (10) is designed with an artificial hysteresis (14), preferably implemented electronically. - in particular, the at least one stabilization control loop (10) automatically initiates different adjustments of the focusing optics (4) and / or the zoom optics (3) depending on the current optical system state and depending on the direction of the detected current temperature change (11), It is preferably irrelevant whether a new target value for adjusting the focusing optical system (4) and / or the zoom optical system (3) is specified from outside the at least one stabilization control loop (10).

3. The method according to any one of the preceding claims, wherein: - directly by means of a temperature sensor (15) and / or - indirectly, in particular by calculating the current electrical power loss of the electronic component (16) based on the visualization system (1) To detect the probe temperature (12); and / or - continuously detecting the corresponding detected temperature (12) as the corresponding current temperature (25); and / or - determining a temperature change (11) relative to a stored reference temperature (40), Preferably, the reference temperature ( 40 ) is adjusted / updated as soon as the stabilization system ( 9 ) intervenes in a closed-loop / open-loop controlled manner.

4. The method according to any one of the preceding claims, wherein: The respective adjustment of the focusing optical system (4) and / or the zoom optical system (3) is performed at different times depending on the current optical system state, in particular depending on the current adjustment of the focusing optical system (4) and the currently set zoom level (17) with respect to the at least one currently detected temperature change (11), - in particular for this purpose the at least one temperature threshold value (18) is adjusted as a function of the current state of the optical system, In particular, the temperature stabilization is intervened in such a way that it stabilizes at small temperature changes ( 11 ) of the detection temperature ( 12 ) or is intervened in such a way that it stabilizes only at large temperature changes.

5. The method according to any one of the preceding claims, wherein: The at least one stabilization control loop (10) operates even when no new optical system state is specified as a target by the visualization system (1) itself or by a user. - in particular, the state of the optical system which has been set once is continuously stabilized by the stabilization system (9) against temperature fluctuations, Particularly preferably, no user intervention is necessary and / or the user does not perceive intervention of the open-loop control of the stabilization system (9) in the real-time image recorded by the at least one image sensor (6).

6. The method according to any one of the preceding claims, wherein: When at least one temperature threshold value (18) and / or at least one position threshold value is exceeded, the at least one stabilization control loop (10) controls at least one actuator (19), in particular a stepper motor (20), of the focusing optical system (4) and / or the zoom optical system (3). - in particular for adjusting the focusing optics (4) and / or the zoom optics (3) along an optical z-axis (21) of the imaging optics (2), In particular, the at least one stabilizing control loop (10) controls the respective actuator (19) via a separate respective control loop (22), by means of which the actuator (19) can be regulated in a closed-loop controlled manner.

7. The method according to any one of the preceding claims, wherein: - the stabilization system (9) adjusts the focusing optical system (4) and / or the zoom optical system (3) in an open-loop controlled manner as soon as the at least one current temperature change (11) of the detected temperature (12) exceeds an associated temperature threshold value (18) which is still permissible for the current optical system state, - preferably independently of the respective target values ​​previously set by the user or by the visualization system (1) for the adjustment of the focusing optical system (4) and / or for the adjustment of the zoom optical system (3), - in particular, no target actual value is present for the corresponding adjustment variables of the focusing optical system (4) and / or the zoom optical system (3), for example the last predetermined focal length (23) or the last predetermined optical zoom level (17), The stabilization system (9) is preferably able to intervene in stabilizing the optical system state even if no new instructions for adjusting the focus optics (4) and / or for adjusting the zoom optics (3) are output by the user or by the visualization system (1).

8. The method according to any one of the preceding claims, wherein: - a stabilization system (9) regulates the focusing optical system (4) and / or the zoom optical system (3) in an open-loop controlled manner based on a corresponding temperature model, in particular and in this case with deviations from a corresponding target value which was last predetermined, in order to stabilize the current optical system state with respect to the at least one current temperature change (11) detected, - in particular, a corresponding temperature model models the necessary temperature-dependent adjustments (eg ΔZL(T, ΔT, FL, ZL)) of the focusing optics (4) or zoom optics (3), for example ΔFL(T, ΔT, FL, ZL), Particularly preferably, the temperature model takes into account the current optical system state (FL, ZL), in particular the current focal length FL of the focusing optics (4) and / or the current zoom level ZL of the zoom optics (3).

9. The method according to any one of the preceding claims, wherein: - the stabilization system (9) - preferably based on a temperature model - calculates a suitable compensating adjustment of the zoom optics (3) and / or the focus optics (4) based on the detected at least one current temperature change (11), in particular a corresponding suitable adjustment path Δz (24) along the optical z-axis (21), and - generating corresponding control signals (49) for adjusting the zoom optical system (3) and / or the focus optical system (4), in particular control signals for intervening in the corresponding separate control loop (22), In particular, in order thereby to stabilize the current optical system state in a temperature-dependent manner.

10. The method according to any one of the preceding claims, wherein: The stabilization system (9) takes into account the detected value of the current probe temperature T (12) and - preferably after the stabilization system (9) has intervened in an open-loop controlled manner - adjusts, according to the detected value of the probe temperature T (12): - the at least one temperature threshold ΔT max (T) (18), the stabilization system (9) intervenes in an open-loop controlled manner starting from this temperature threshold, and / or - Corresponding temperature models (ΔFL(T, ΔT, FL, ZL), ΔZL(T, ΔT, FL, ZL)).

11. The method according to any one of the preceding claims, wherein a current change ΔT of the detection temperature (12), preferably also the current detection temperature T(12), is detected in at least two spatially different detection regions (13), preferably within the imaging optical system (2), and / or -in, The at least one current temperature change (11) is used as an input variable of the at least one stabilization control loop (10), so that the stabilization control loop (10), in particular a corresponding stabilization control loop, of the stabilization system (9) is triggered by, in particular only by, the temperature change (11) - in particular but not by a change in a current target value for the state of the optical system.

12. The method according to any one of the preceding claims, wherein: Current optical system status: - indirectly by adjusting the at least one temperature threshold value (18) caused by an externally initiated change in the system state and / or - by actively adjusting the current settings of the focusing optical system (4) and / or the zoom optical system (3), in particular due to a detected excess of the at least one temperature threshold value (18) and is stabilized, In particular, the stabilization system (9) intervenes because the at least one temperature threshold value (18) ΔT(T) is temperature-dependent and the currently detected temperature (25) T has changed, so that the previously detected current temperature change (11) now exceeds the adjusted temperature threshold value (18) ΔT(T).

13. A visualization system (1), preferably designed as part of a robotic system (26) and / or as a medical visualization system (1), The visualization system comprises an imaging optical device (2), wherein the imaging optical device comprises: - an adjustable zoom optic (3) for determining a current optical zoom level (17), and - adjustable focusing optics (4) for determining the current spatial position of the focal plane, at least one image sensor (6) for acquiring at least one image of an object (7), such as an operating area (8), observed with the visualization system (1), and at least one temperature detector (27) which is configured to directly measure by sensory means and / or indirectly detect by non-sensory means at least one current temperature change (11) of a detection temperature (12) in at least one detection region (13), It is characterized in that The imaging optical system (2) is arranged in a dust-proof housing (28), and the at least one detection area (13) is located in the housing (28), the visualization system (1) comprises a stabilization system (9) with at least one stabilization control loop (10), by means of which the current optical system state of the visualization system (1) can be actively stabilized based on the at least one current temperature change (11) measured and / or indirectly detected, The visualization system ( 1 ), in particular the stabilization system ( 9 ), is preferably configured to carry out the method according to one of the preceding claims.

14. Visualization system (1) according to the preceding claim, -in, The at least one temperature detector (27) is arranged in the housing (28) in close proximity to the optical lens (29) of the imaging optical device (2), for example on a lens seat (30), and / or - The at least one temperature detector is arranged at at least one position in the housing (28), at which the thermal expansion of the optomechanical components of the imaging optical device (2) significantly affects the position and / or orientation of the focusing optical device (4) and / or the zoom optical device (3) respectively with respect to the optical z-axis (21) of the imaging optical device (2).

15. The visualization system (1) according to one of the preceding claims, wherein: The visualization system (1) - comprises at least one stepper motor (20) which is configured to adjust the focusing optical system (4) and / or the zoom optical system (3), in particular via the intermediary of a mechanical spindle, - preferably, at least two stepper motors (20) are designed for adjusting the zoom optics (3) and at least one stepper motor (20) is designed for adjusting the focus optics (4), In particular, each stepper motor (20) is coupled to the at least one stabilization control loop (10), in particular the respective stabilization control loop (10), in particular via its own control loop (22), so that the stabilization system (9) can control the respective stepper motor (20) in an open-loop controlled manner.

16. The visualization system (1) according to the preceding claim, wherein: The visualization system (1) has at least one control unit (31) for controlling and thereby adjusting the focusing optical system (4) and / or the zoom optical system (3), in particular by means of at least one stepper motor (20), and the stabilization system (9) is configured to stabilize a current optical system state by means of the control unit (31). Preferably, the current optical system state is stabilized even if neither the user nor the visualization system ( 1 ) is seeking a change in the system state or prescribing a change in the system state by means of a new target for the system state.

17. The visualization system (1) according to one of the preceding claims, wherein: An artificial, preferably electronically implemented hysteresis (14) is provided in the stabilization system (9), in particular based on at least one, preferably variable, temperature threshold value (18). Preferably, intervention of the stabilization system (9) to stabilize the current optical system state is carried out in the event of a temperature change (11) while avoiding image jitters of the image recorded by the visualization system (1) that are perceptible to a user.

18. Visualization system (1) according to the preamble of claim 13, in particular according to one of claims 13 to 17, characterized in that The visualization system (1), in particular the stabilization system (9) of the visualization system (1), is configured to carry out the method according to one of claims 1 to 12.

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