Test device, system and test procedure

Abstract

Test device (10), comprising: a light supply (12) which is designed to carry first illumination light; a conversion element (14) configured to convert light from the first illumination light with a first wavelength (16) at least partially into second illumination light with a second wavelength (18) different from the first wavelength (16); and an optical target (20) which is arranged such that first illumination light and second illumination light can be supplied to it for illuminating the target (20) in order to capture a calibration image (22) of the optical target (20).

Description

[0001] The present application relates to a test device, a system and a test procedure.

[0002] In medical imaging, exoscopes are state-of-the-art, enabling the creation of three-dimensional (magnified) representations of an examination area. For example, such exoscopes can be used to visualize microsurgical and / or open procedures to assist a surgeon. The three-dimensional representation allows the surgeon to more intuitively assess and / or monitor their own actions on a screen.

[0003] To generate the spatial representation, such exoscopes have at least two image acquisition units, each capturing an image of the examination area. These image acquisition units must be geometrically calibrated as precisely as possible, which means, in particular, that they must be aligned relative to each other to capture images within a common coordinate system. Otherwise, the spatial representation would be inaccurate, and viewing the image, especially over extended periods, could lead to increased cognitive strain on the surgeon, potentially resulting in headaches or other physical discomfort.

[0004] Furthermore, the exoscopes can have image acquisition devices that are additionally configured to capture images in a wavelength range different from the visible light range. For example, this different wavelength range can be in the near-infrared region, and luminescence imaging, such as fluorescence imaging, can be performed using these image acquisition devices. Images based on luminescence imaging can be superimposed on other images to provide the surgeon with additional information about the area under examination. Therefore, it is necessary that these image acquisition devices are also coordinated with the other image acquisition devices, i.e., that they have a common geometric calibration.

[0005] Typically, geometric calibration is performed at the factory, and an exoscope is delivered to the customer in a calibrated state. The factory calibration is then verified before delivery. Bulky test equipment is used for this verification. This equipment must have various illumination devices and / or light sources, each providing light in the wavelength range used by the image acquisition devices. For example, it is common for the test equipment to include a (near) infrared light source and a white light source.

[0006] DE 10 2022 102 547 A1 discloses a method and measuring system for the three-dimensional measurement of objects.

[0007] From DE 10 2020 201 806 A1 a reference sample for the calibration and / or adjustment of a microscope is known as well as uses of the reference sample.

[0008] FR 2 921 479 A1 discloses a system and method for capturing three-dimensional features of an object from images taken by several measuring bodies, as well as a method for calibrating such a system.

[0009] Based on the prior art, the invention aims to provide a simple and flexible way to check geometric calibration.

[0010] This problem is solved according to the invention by a test device, a system and a test method as described herein and defined in the claims.

[0011] The present invention may provide a testing device comprising a light supply configured to guide first illumination light, a conversion element configured to convert light of the first illumination light with a first wavelength at least partially into second illumination light with a second wavelength different from the first wavelength, and an optical target arranged such that first illumination light and second illumination light can be supplied to it for illuminating the target in order to acquire a calibration image of the optical target.

[0012] Furthermore, a system comprising a test device and a medical imaging device with an image acquisition unit may be provided. The image acquisition unit may include a first image acquisition device, which is light-sensitive in a first spectral range encompassing the first wavelength, and a second image acquisition device, which is light-sensitive in a second spectral range different from the first, encompassing the second wavelength. The image acquisition unit may feature geometric calibration of the first and second image acquisition devices with respect to their imaging ranges and may be configured to acquire calibration images of the optical target. Furthermore, the geometric calibration of the image acquisition unit may be verifiable using the calibration images.

[0013] Furthermore, a test procedure may be provided. The test procedure may include the steps of generating first illumination light comprising light with a first wavelength, generating second illumination light comprising light with a second wavelength different from the first, supplying the first illumination light and the second illumination light to an optical target for illumination, and acquiring calibration images of the target using a medical imaging device with an image acquisition unit, wherein the image acquisition unit comprises a first image acquisition device that is light-sensitive in a first spectral range and a second image acquisition device that is light-sensitive in a second spectral range different from the first, which comprises the second wavelength.wherein the image acquisition unit comprises a geometric calibration of the first image acquisition device and the second image acquisition device with respect to their imaging ranges, and a verification of the geometric calibration of the image acquisition unit against the calibration images of the optical target. The generation of the second illumination light may comprise a conversion of light from the first illumination light with the first wavelength, at least partially, into second illumination light with a second wavelength different from the first wavelength.

[0014] According to one aspect, the present invention may provide a test method for verifying the geometric calibration of an image acquisition unit using a calibration image of an optical target. This may be a further development of the aforementioned test method or an independent test method. The image acquisition unit may comprise a first image acquisition device and a second image acquisition device, wherein the image acquisition unit incorporates the geometric calibration of the first image acquisition device and the second image acquisition device with respect to their imaging areas. The image acquisition unit may be configured to acquire calibration images of the optical target, and the geometric calibration of the image acquisition unit may be verifiable using these calibration images. Furthermore, the optical target may comprise at least one calibration pattern.Furthermore, the test procedure can include a verification process with the steps of capturing a first calibration image using the first image acquisition device and a second calibration image using the second image acquisition device, such that these each depict the calibration pattern, creating a calibration representation with a superimposed representation based on the first calibration image and the second calibration image, wherein the superimposed representation includes an image of the calibration pattern at least partially, and verifying the geometric calibration using the image of the calibration pattern in the superimposed representation.

[0015] The test methods, systems, and / or test devices can be independent of one another. Some embodiments can also use features of different test methods, systems, and / or test devices and / or partially or completely combine several test methods, systems, and / or test devices.

[0016] Advantageously, geometric calibration can be easily and flexibly verified. In particular, geometric calibration can be verified after delivery of the exoscope to a customer and / or at regular test intervals. Consequently, it can be easily and flexibly verified whether the customer has received and / or is operating a sufficiently geometrically calibrated exoscope. Thus, with regard to calibration, it can be ensured that the exoscope operates within the specified tolerance ranges and that it produces images that are comfortable for an operator to view, especially over extended periods. Furthermore, it is advantageous that no heavy and / or unwieldy test equipment needs to be transported to the customer to verify the geometric calibration.Furthermore, the test procedure for verifying geometric calibration does not require a particularly powerful computing unit, but can be performed with standard computing units. The test device can be compact and designed for transport to the customer. Nevertheless, the test device can be used to verify the geometric calibration of image acquisition units, including image acquisition devices that are light-sensitive in different spectral ranges. This, and / or the compactness, can be achieved by including the conversion element in the test device. This means that only the first illumination light needs to be routed from the light source to provide the first and second illumination lights. The simplicity of verifying the geometric calibration is further enhanced by the fact that the calibration can be checked using the calibration images.Calibration images can be captured in the same or at least a very similar way as images would be captured during normal operation. Therefore, the image acquisition unit does not need to be specially designed for verifying the optical calibration. This also allows for flexible use of the test device, particularly with different image acquisition systems. Furthermore, the geometric calibration can be easily verified using the calibration pattern. Using the optical target provides a cost-effective and quick way to check the calibration. The use of the overlay display allows for efficient on-site calibration verification.

[0017] The test device can, in particular, be a calibration test device for verifying geometric calibration. The test device can, in particular, be configured for verifying the geometric calibration of medical imaging devices, wherein the imaging device comprises an image acquisition unit.

[0018] The light supply can be configured to provide illumination such that the optical target is illuminated and / or the conversion element is at least partially illuminated. Guiding can mean that the light can be directed in a preferred direction. Generally, guiding can mean that light is directed from a point where illumination is coupled out of a light source to the target by means of one or more optical elements. This can include both beam guiding and diffuse directional scattering. In particular, the light supply can be configured to guide light with high efficiency, for example, with a power loss of no more than 50%, no more than 40%, no more than 30%, or even no more than 20%. Furthermore, light can be coupled into the light supply.

[0019] Illumination light can generally encompass wavelengths belonging to the visible light spectrum. Illumination light can be understood as light intended for illuminating and / or illuminating a body and / or object. The initial illumination light may, for example, be intended for illuminating the conversion element and / or the optical target. For this purpose, light, particularly illumination light, can be directed within the test device. The initial illumination light can, in particular, be light that can be coupled into and / or generated within the light supply. Furthermore, the initial illumination light can, in particular, be directed onto the conversion element via the light supply.

[0020] In principle, "light in a specific range" can mean that a portion of the total spectral intensity distribution of the light lies within that range. The spectral intensity distribution can be defined as the distribution of light intensity across the various wavelengths of the entire spectrum. For example, the portion can be 10% to 100%, more preferably 40% to 100%, and preferably 80% to 100%. Particularly preferably, "part" can mean that the light intensity is distributed such that at least substantially the light intensity lies within the specified spectral range. If the spectral range is, for example, visible light, then the light intensity is substantially distributed across the spectral range of visible light. This can be particularly relevant when features relate to the initial illumination light and / or the first wavelength.

[0021] The conversion element can be configured to convert light of the first wavelength, in particular light from the first illumination source, into light of the second wavelength, in particular light from the second illumination source. Furthermore, the conversion element can be partially transparent to light of the first wavelength. For example, the conversion element can be configured to convert 10% to 100%, in particular 30% to 80%, preferably 40% to 60% of the amount of light and / or the luminous flux of the light of the first wavelength into light of the second wavelength. In addition, the conversion element can be configured to convert light into narrow spectral bands, according to the other features. "Narrow" can mean that the converted spectral band is, for example, up to 200 nm, in particular 100 nm, preferably 50 nm, and particularly preferably 20 nm wide. The conversion element can, in particular, be configured to emit light of the second wavelength.The emitted light can be used to illuminate the optical target. Alternatively or additionally, light with the first wavelength can be used to illuminate the optical target. For example, the conversion element can be configured to alternately convert and transmit light over time.

[0022] The conversion element can include filters configured for light conversion. In particular, the conversion element can be configured to absorb light of the first wavelength and emit light of the second wavelength. Furthermore, in some embodiments, the wavelength of the light of the first wavelength can alternatively or additionally be halved by means of the conversion, for example, by frequency doubling (second harmonic generation, SHG) and / or frequency multiplication using nonlinear optical processes. For example, the second wavelength can be a wavelength from the ultraviolet range. Furthermore, quantum dots can be provided for light conversion, or the conversion element can include quantum dots.

[0023] The conversion element can comprise a transparent or semi-transparent panel. Alternatively or additionally, the conversion element can comprise a translucent panel. Furthermore, the conversion element can comprise a coating that allows a greater amount and / or luminous flux of the second wavelength to be emitted. Alternatively or additionally, the conversion element can comprise a film, in particular a frosted film, and / or be laminated. The optional panel of the conversion element can, for example, be covered with the film on one side and / or both sides. "One side and / or two sides" can refer in particular to the sides onto which light of the first wavelength can be directed, or from which light of the second wavelength can be emitted.

[0024] The optical target can serve as a target or object against which an optical system, particularly a medical imaging system, can be aligned or calibrated. The optical target can comprise a structure that, when imaged, allows the acquisition of the calibration image. This can mean that optical calibration can be performed using an image of the optical target's structure. The optical target can be illuminated by light of the first wavelength, particularly the first illumination light, and by light of the second wavelength, particularly the second illumination light, or such light can be supplied to it. For example, the optical target can comprise sections of opaque areas and / or segments that can be used for optical calibration when imaged and / or acquired by means of the calibration image.For example, an optical target can be used to define a target point, and the geometric calibration can be checked with reference to this target point. Furthermore, multiple target points can be provided. For example, the geometric calibration can be checked in several areas of the imaging fields of the image acquisition devices using the optical target.

[0025] The calibration image can be an image that is primarily intended for verifying the geometric calibration. The calibration image can be captured using predefined and / or standardized image acquisition settings. This can mean that the image acquisition devices, the image acquisition unit, and / or the medical system can have defined settings during the acquisition of the calibration image. It can be provided that a sequence of calibration images, in particular a calibration video, is captured. For example, calibration images can be captured at least substantially in real time and / or transmitted to a display device, and / or the calibration images can be displayed on the display device at least substantially in real time. In particular, the calibration can be verified using a sequence of calibration images.

[0026] The medical imaging device may preferably be an exoscope. Alternatively or additionally, the imaging device may be an endoscope. The medical imaging device may be configured to acquire images of an examination area. In some embodiments, the imaging device may be configured to generate magnified images of the examination area. The image can be viewed during a medical procedure and / or during a diagnostic procedure. The medical imaging device may be mobile and / or movable. It may be designed to be movable, for example, within an operating room. If a user requires imaging support, the imaging device may be movable to the point of use, such as a patient. The imaging device may also be movable within itself.The image acquisition unit may, for example, include a movable support arm and / or the image acquisition unit may be arranged on the movable support arm.

[0027] The image acquisition unit can be configured to capture images. Furthermore, the image acquisition unit can comprise the imaging component of the imaging device. For example, the image acquisition unit can house the components involved. The image acquisition unit can be optionally attached to and / or detached from the support arm. This can mean that the image acquisition unit is interchangeable with another image acquisition unit. The image acquisition unit can also include connections by means of which image data, signals, and / or electrical power can be exchanged with and / or transmitted between the medical imaging device, in particular with a control unit of the imaging device.

[0028] The image acquisition unit can comprise several image acquisition devices, for example, two, three, four, five, and / or six. Each image acquisition device can include an image sensor. The image sensor can be, for example, a CCD sensor and / or a CMOS sensor. Furthermore, each image acquisition device can include an optical device by means of which light can be directed onto the image sensor. The light can be coupled into the image acquisition unit by means of an input optic. For example, each image acquisition device can have its own input optic. Preferably, however, the image acquisition unit comprises an input optic by means of which light can be coupled to all image acquisition devices. The coupled-in light can then be split among the image acquisition devices, for example, by means of a beam splitter. The input optic can include a converging lens. All image acquisition devices can have a common image plane.

[0029] The image acquisition devices can be at least substantially identical in construction. Preferably, all image acquisition devices can have at least substantially the same image acquisition characteristics. For example, the light can be directed onto the image sensor in the same way and / or the distance to the input optics can be the same. The image acquisition devices can also be configured to image the same imaging area. This is particularly true if the image acquisition devices have good geometric calibration with each other. The image acquisition devices can image the imaging area from slightly different viewing angles. This can, for example, create a spatial representation of the imaging area. This can mean that the image acquisition unit can be at least partially a stereo image acquisition unit.

[0030] Alternatively or additionally, the image acquisition unit can be configured to guide light in different spectral ranges and / or to image the target area in different spectral ranges. For this purpose, the first image acquisition unit can be light-sensitive in the first spectral range, and the second image acquisition unit can be light-sensitive in the second spectral range. For example, the image sensor can be light-sensitive in the visible light range, the ultraviolet light range, and / or the near-infrared spectral range. "Light-sensitive" can be understood to mean, in particular, that the respective image sensor is configured to detect light in the specified region of the electromagnetic spectrum, or the specified wavelength range, and / or to capture images.The image sensor can also be light-sensitive in the specified range and additionally in a wavelength range beyond. For example, an image sensor can be light-sensitive in the near-infrared wavelength range and additionally in the visible light range.

[0031] The wavelength range of visible light can generally be understood as the wavelength range between approximately 380 nm and 780 nm, and more specifically between 400 nm and 700 nm.

[0032] The geometric calibration of an image acquisition unit can be understood as aligning the unit in such a way that images can be captured within a specific coordinate system. This can mean that the unit is aligned to a specific point and / or pattern. The imaging range of a geometrically calibrated image acquisition unit is within a specific expected range, within the limits of expected and / or application-specific tolerances. These tolerances are determined, for example, by the need for precise geometric calibration. For some embodiments, a tolerance of, for example, 1 pixel to 100 pixels, in particular 3 pixels to 50 pixels, and preferably 5 pixels to 25 pixels, may be sufficient.Two image acquisition units that share a common geometric calibration can, for example, be configured to map images of imaging areas in a common coordinate system. In particular, a point in space mapped by one of the geometrically calibrated image acquisition units can be located at a first location of the image of that image acquisition unit, and the same point in space mapped by the other geometrically calibrated image acquisition unit can be located at at least a second location of the image of that image acquisition unit, the first location corresponding at least substantially to the second location with respect to the image boundaries.

[0033] Generally speaking, the pixel size of different imaging devices can vary. A specified number of pixels should be understood in the context of common pixel sizes. For example, a pixel can be between 10 µm and 1 mm in size.

[0034] The geometric calibration can be verified using the calibration images from the image acquisition unit. This means, for example, that the relative position of an image of the optical target in two calibration images can be compared to each other in order to check the geometric calibration. A deviation in the relative position between two calibration images may indicate insufficient geometric calibration. Conversely, a deviation in the relative position may indicate sufficient calibration, provided the deviation is within a tolerance range. The calibration images can be acquired using any of the image acquisition devices.

[0035] According to some embodiments, the second wavelength can be a wavelength from the infrared range, particularly from the near-infrared range. This can mean that light with the first wavelength can be converted into light with the second wavelength by means of the conversion element, the second wavelength being attributable to near-infrared light. The conversion element can, in particular, be configured to emit and / or radiate infrared, especially near-infrared, radiation. Near-infrared radiation can, for example, have a wavelength of approximately 780 nm to 3 µm. Infrared radiation can generally have a wavelength of approximately 780 nm to 1000 µm. Furthermore, in this context, the imaging area of ​​an image acquisition unit can be imaged in infrared, especially near-infrared, radiation. This can be the case for at least a sub-range of the infrared and / or near-infrared range.Depending on the sensor used, infrared light can be detected in different spectral ranges. Advantageously, this allows for the acquisition of information about an object that goes beyond what can be obtained from imaging with visible light. For example, molecules present in the imaging range can emit near-infrared radiation. The presence and / or quantity of these molecules can be verified by imaging with near-infrared radiation. For instance, specific tissue types and / or structures can be selectively labeled with these molecules. These molecules can be dyes, particularly fluorescent dyes. In some embodiments, they can also be native molecules, such as endogenous proteins. Detection can then be directed toward autofluorescence.The tissue types can include, for example, cancerous tissue. By labeling cancerous tissue with molecules that emit near-infrared light, the presence of this tissue in the imaging area can be inferred. For example, an image based on near-infrared radiation can be generated and made available to the user. For example, the near-infrared radiation can be color-coded. Furthermore, an image based at least partially on near-infrared radiation can be superimposed on an image based at least partially on visible light.Furthermore, it is advantageous that the second wavelength comprises a wavelength from the infrared range, particularly from the near-infrared range, since this eliminates the need for the test device and / or system to include a separate illumination device for generating light of the second wavelength when verifying the geometric calibration of an image acquisition device that is photosensitive in the second spectral range. This allows for a particularly compact test device. Furthermore, a cost-effective and / or less error-prone test device can be provided. Advantageously, the test device can be flexibly and / or easily transported to a customer for geometric calibration verification.In particular, it can be avoided that a bulky, expensive, complex and / or heavy test device is needed to check the geometric calibration and / or has to be transported to a customer.

[0036] The terms "encompassing," "generating," and / or "converting" can generally mean "at least predominantly" encompassing, generating, and / or converting. "At least predominantly" encompassing, generating, and / or converting can refer specifically to the spectral distribution of light intensity. In this context, "at least predominantly" can mean that a major component of the spectral intensity distribution lies within the specified spectral range. For example, at least 80%, in particular at least 90%, preferably at least 95% of the light intensity can be located within the specified spectral range. If, for example, illumination light includes at least predominantly light from the visible range, this can mean that at least 95% of the light intensity can be attributed to the spectral range of visible light.

[0037] Furthermore, the initial illumination can consist predominantly of light from the visible spectrum. Such illumination can be provided by readily available, common light sources, in particular in a simple and / or efficient manner.

[0038] Furthermore, the conversion element can be configured to convert at least some visible light into infrared light. Easily available light can therefore be converted into less readily available light. Infrared light sources can be more expensive and / or less readily available than white light sources. This is particularly relevant since a white light source is typically present in an operating room, but not an infrared light source. By configuring the conversion element in this way, a particularly simple, efficient, cost-effective, and / or compact testing device can be provided.

[0039] According to some embodiments, the conversion element can have luminescent properties, wherein the conversion element is configured to convert, by means of these luminescent properties, light from the first illumination source with the first wavelength into the second illumination source with a second wavelength different from the first. For example, the conversion element can have fluorescent and / or phosphorescent properties. The conversion element can, for instance, have a coating, be formed, at least partially, from a material alloy, or comprise a material that is luminescent, in particular fluorescent and / or phosphorescent. The conversion element can be configured to absorb light with one wavelength, in particular the first wavelength, and to emit light with another wavelength, in particular the second wavelength.This allows the conversion element to be manufactured inexpensively and / or compactly. Furthermore, different second wavelengths can be provided flexibly and / or efficiently, particularly selectively. For example, various conversion elements with different optical properties can be provided, which can be quickly interchanged.

[0040] Furthermore, the test device can include a mount, the mount being designed to allow the test device to be coupled to a medical imaging device under test. The mount enables the geometric calibration check to be performed reproducibly. Additionally, the test device can be easy to operate, in particular by being efficiently, easily, and / or simply alignable with the imaging device.

[0041] The mount can also include a spacer that defines a distance between the medical imaging device under test and the target. This distance can, for example, correspond approximately to the distance that the imaging device, in particular an image acquisition unit and / or the input optics of the imaging device, is typically positioned at a distance from the object under examination in a typical operating environment. Furthermore, the distance can be specifically tunable with the optical target and / or with the imaging device. The distance can correspond at least substantially to a focal length of the first image acquisition unit and / or a focal length of the second image acquisition unit. In some embodiments, the distance can be at least 5 cm, at least 10 cm, or at least 20 cm and / or at most 100 cm, at most 80 cm, or at most 50 cm. This can increase the reproducibility of the inspection.Furthermore, the verification process can be standardized.

[0042] Furthermore, the mounting can be designed to support the test device's own weight when coupled to the medical imaging device under test. This can mean that the test device can be coupled to the imaging device in such a way that it does not rest on the floor. In other words, the test device does not need to include a support leg or similar structure. This allows for a more dynamically efficient coupling of the test device and imaging device system. Advantageously, fewer vibrations and / or less vibrational energy can be transmitted to the test device via the floor. The accuracy of the inspection can be improved. Furthermore, the test device can be designed more compactly.

[0043] The mount can also include a coupling section for connecting to the medical imaging device under test, wherein the coupling section comprises a projection configured to hold the device under test by engaging behind it. The imaging device can also include a holding section to which the mount can be coupled. For example, the projection can engage behind the holding section, at least partially. Furthermore, the projection can be configured to hold the device under test during coupling by engaging behind it, in particular at least partially behind the holding section. The device under test can be rotated about the projection during coupling, in particular while the projection is partially engaging behind the holding section. The projection can be rotatably mounted in the holding section.The test device, in particular the coupling section and / or the projection, and the imaging device, in particular the holding section, can together form a connection. The connection can, for example, include a dovetail joint. This can result in a compact and / or efficient test device.

[0044] The coupling section can further comprise a movable retaining element designed to selectively fix the holder to or detach it from the medical imaging device under test. For example, the retaining element can clamp the holder to the imaging device. Alternatively or additionally, the movable retaining element can be designed to engage the imaging device, particularly the holding section, section by section. The movable retaining element can include, for example, a tensionable retaining element, in particular a clamping spring, an adjusting spring, and / or the like, a screw, and / or a locking lug. This allows the test device to be easily and selectively fixed to and / or detached from the imaging device. Coupling can be performed quickly and / or flexibly.

[0045] Furthermore, the light supply can include a reflective screen designed to direct the illumination light to the conversion element, with the screen having a cross-sectional area that increases towards the conversion element. The screen can, for example, be funnel-shaped and / or conical. Reflective can mean that a large portion of the incident light is reflected back. Reflective can also include diffuse reflection. For example, the screen can include a reflective coating. The coating can be specular. Furthermore, the coating can be white, designed to diffusely reflect light. "White" here refers specifically to the visible spectral range. Light can be directed to the conversion element efficiently and / or without significant light loss.

[0046] Furthermore, the test device can include a fiber optic connection to which a fiber optic cable can be connected such that the first illumination light guided in the fiber optic cable can be coupled into the test device. Advantageously, the test device does not need to include its own light source. In some embodiments, the system and / or the medical imaging device can include a light source. A fiber optic cable from this light source can be connected to the test device. The fiber optic connection can be any standard fiber optic connection. Consequently, if the geometric calibration of a medical imaging device is to be checked, no light source needs to be transported. It is sufficient to transport the test device to the customer. A light source already present there can be connected to the test device. Preferably, the fiber optic cable carries first illumination light that comprises at least predominantly white light and / or visible light.

[0047] Furthermore, the optical fiber termination can be located at a proximal end of the reflecting screen, which has a first cross-sectional area, and the conversion element can be located at a distal end of the reflecting screen, which has a second cross-sectional area, the second being larger than the first. Consequently, an illuminable imaginary cross-sectional area can increase with increasing distance from the optical fiber termination, and / or a relatively large area of ​​the conversion element can be illuminated. The light can also be guided efficiently and / or with low light loss, particularly onto the conversion element.

[0048] Furthermore, the light source can include a diffusion element designed to disperse and homogenize the light from the initial illumination source. The diffusion element can comprise a plate designed for diffusion. For this purpose, the plate can include, for example, a coating. Alternatively or additionally, the plate can comprise a frosted glass plate and / or a milky acrylic sheet. The diffusion element can be located at the distal end of the reflecting screen. The conversion element can be located distal to the diffusion element. In some embodiments, the conversion element can contact the diffusion element. For example, the conversion element can comprise a plate that rests on the diffusion element. The diffusion element and / or the conversion element can be fixed and / or fixable in this configuration.For example, the test device can include a receiving slot into which the diffusion element and / or the conversion element can be inserted. The receiving slot can be closable. The diffusion element enables homogeneous illumination of the conversion element and / or the optical target, thereby increasing the accuracy of the inspection.

[0049] Furthermore, the optical target can be mounted so that it is movable. The test device can include a mounting device in which the optical target is movable. The target can, for example, be movable in a plane that corresponds to a principal plane of the conversion element and / or the diffusion element. The mounting device can be designed to prevent movement of the target perpendicular to this plane, thus restricting its movement to this plane. The principal plane can include the emission plane of the conversion element, from which light is emitted towards the optical target. Furthermore, the plane can be at least substantially parallel to the plane that can be imaged by the imaging unit, particularly in a coupled state, or in which the calibration image is to be acquired by the imaging unit. The optical target can therefore be mounted so that it is movable in the image plane of the imaging unit.The optical target can further comprise at least one handle by means of which the target can be moved. The handle can be removable. The target can be inserted into the storage device, particularly in a state where the handle is removed. Furthermore, the storage device can be designed such that the movement of the target is reduced. For example, the target can be clamped in place. The test device, in particular the storage device, can, for example, include a rubber lining that is compressed by the target when the target is inserted into the test device. This reduces the risk of the target moving unintentionally relative to the imaging device. Operator safety is increased. Because the target is movable, it can be aligned relative to the imaging device.

[0050] Furthermore, the optical target can include at least one calibration pattern, and the calibration pattern can be imaged on the calibration image. The calibration pattern can be clearly recognizable in the calibration image and / or, for example, be displayed with a sharp contrast and / or in a different color than the surroundings. The calibration pattern can be designed such that the verification of the geometric calibration using the calibration pattern can be carried out easily and / or quickly. In some embodiments, the calibration pattern includes opaque, light-reflecting, and / or light-absorbing sections. The calibration pattern can, for example, include a black print on a film. Furthermore, the calibration pattern can be formed as a relief in a plate, wherein the relief can be filled with a black and / or light-absorbing material.A film containing the calibration pattern can, for example, be placed between two translucent plates, especially glass plates, or clamped and / or stretched between them. The plates help reduce the risk of damage to the calibration pattern.

[0051] The calibration pattern can further comprise at least one line and / or a cross. In some embodiments, the line and / or cross can also include isolated elements such as dots, dashes, or other objects arranged on the line and / or cross, thereby forming the line and / or cross. The line and / or cross is easily recognizable in the calibration pattern. Furthermore, it is particularly well suited for verifying the optical calibration. A cross is preferentially provided. Using the cross, the optical calibration can be easily verified in two spatial directions.

[0052] Furthermore, the calibration pattern can comprise a central rectangular cross with elongated arms, the center of which can be positioned in the center of the calibration image, and which divides the calibration image into four quadrants. In each of the four quadrants, another rectangular cross with elongated arms is arranged, the center of each of these elongated arms being located in a central region of the respective quadrant. Elongated arms can mean that the cross can have thin arms. When the cross is imaged, an arm can extend in width, for example, from 1 pixel to 20 pixels, in particular from 1 pixel to 10 pixels, preferably from 1 pixel to 5 pixels. The center of the central cross can be moved to the center of the calibration image by moving the optical target. This allows the geometric calibration to be checked at the center.The four additional right-angled crosses in the central areas of the quadrants of the calibration image allow the geometric calibration to be verified in the peripheral areas of the calibration image. A central area can refer to a region of the quadrant that encompasses the center of the quadrant. The center of the quadrant can encompass at least substantially the center of the central area. The central area can cover, for example, up to 50%, in particular up to 30%, preferably up to 15% of the quadrant's area. The central area can, in particular, be located in the center of the quadrant. This can mean that, overall, the geometric calibration can be verified in a region of the calibration image that extends from the center in both directions, encompassing at least substantially half of the side edge.Consequently, it can be ensured that the image acquisition unit has good geometric calibration over a large imaging area. This allows for particularly good image quality and excellent spatial representation.

[0053] Furthermore, the optical target can be integrated with the conversion element. For example, the calibration pattern can be printed onto the conversion element and / or a film encompassing the optical target can be stretched onto the conversion element. Advantageously, the test fixture can be made more compact and / or lighter. Moreover, the complexity of the test fixture can be reduced.

[0054] The system may further include a lighting device that is connected to and / or connectable to the light supply. The lighting device may include a light source, in particular a white light source. Advantageously, the lighting device may provide light comprising the first wavelength, in particular the first illumination light. The lighting device may be connected to the light supply, in particular by means of an optical fiber.

[0055] Furthermore, in an imaging operating mode, the illumination device can be connected to the imaging device to provide illumination during image acquisition. In a calibration operating mode, the illumination device can be connected to the test device to provide illumination. Advantageously, an illumination device can be provided to supply illumination to both the imaging device and the test device. Imaging devices regularly have an illumination device and / or an illumination device is provided for the operation of the imaging device anyway. This means that an illumination device is usually present if an imaging device is present. The test device can then be operated with this illumination device.This eliminates the need for a separate lighting device to check the geometric calibration.

[0056] Furthermore, the system can include a display device configured to present a calibration representation based on the calibration images to a user. In imaging mode, the display device can show images of an object, the images being acquired by the imaging device. The representation can, in particular, include a spatial representation and / or a superimposed representation. Advantageously, a display device that is already available can be used for verification.

[0057] The calibration images can comprise at least one first calibration image acquired by the first image acquisition device and at least one second calibration image acquired by the second image acquisition device. The calibration representation can include a superimposed representation based on the first and second calibration images. "Superimposed representation" can mean that the representation is based on both calibration images. For example, a superimposed representation can be understood as a blended representation. The superimposed representation can, for example, comprise the first and second calibration images, with at least one of the calibration images being displayed semi-transparently. In the superimposed representation, image areas of the respective calibration images can be compared and / or aligned. For example, the spatial position of components of the calibration images can be compared.This allows the geometric calibration to be verified.

[0058] Furthermore, the superimposed representation can comprise spatially adjacent sections of the first calibration image and the second calibration image. The sections of the calibration images can be approximately 5 to 500 pixels in size, in particular 20 to 250 pixels, preferably 30 to 100 pixels, especially with respect to at least one side length. In some cases, the sections can be square and / or rectangular. The pixel dimensions can then refer to the length of one side, in particular a longer side. The size can refer to the extent in a spatial direction. This allows the verification of the geometric calibration by a section-by-section comparison of the calibration images. In this way, it can be easily verified whether the calibration images depict an object, for example, the optical target, identically in the sections, in particular with the same position.A misalignment of these images suggests a quality of geometric calibration.

[0059] Furthermore, the overlay representation can comprise multiple alternating sections of the first and second calibration images arranged side-by-side in two different spatial directions. For example, the calibration representation can have a checkerboard pattern. The squares of the checkerboard can comprise adjacent sections of the first and second calibration images. This allows the geometric calibration to be verified in both spatial directions.

[0060] The optical target can encompass the calibration pattern, and the sections of the respective calibration images used for the overlay can at least partially depict the calibration pattern. This allows verification of whether there is an offset of the calibration pattern in the overlay. The offset is an indicator of the quality of the geometric calibration. The geometric calibration can thus be easily verified.

[0061] The system may further include an input device by means of which a user can issue control commands to verify the calibration of the image acquisition unit. The input device may include a laptop, a computer, a mobile device such as a mobile phone and / or a tablet, in particular a mouse and / or a keyboard. For example, the arrow keys on the keyboard may be used to issue a control command to move an overlay. Furthermore, during the verification process, the system may be navigable via a menu, which may be designed to allow users to navigate through the geometric calibration verification steps.

[0062] Furthermore, the display device can be configured to show an alignment aid for aligning the optical target relative to the image acquisition unit. The alignment aid can, for example, be designed to assist in moving the calibration pattern, particularly the central cross, to the center of the calibration image. For instance, the alignment aid can mark the center and / or the middle of the calibration image and / or the superimposed display, and the optical target can be aligned using the alignment aid. Advantageously, the optical target can be easily aligned within the test device. In particular, the optical target can be specifically designed for the imaging device. In some embodiments, the alignment aid comprises a central cross with elongated arms.The optical target can be moved in such a way as to align it so that as much of the representation of the target image as possible overlaps the alignment aid.

[0063] According to some embodiments, the image acquisition unit can comprise a third image acquisition device, which is light-sensitive in the first spectral range, and a fourth image acquisition device, which is light-sensitive in the second spectral range. Stereo image acquisition in the first spectral range can be performed using the first and third image acquisition devices, and stereo image acquisition in the second spectral range can be performed using the second and fourth image acquisition devices. For example, stereo image acquisition can be performed in the visible light spectral range and additionally in the near-infrared and / or ultraviolet spectral range. A stereo representation, in particular a spatial representation, can be generated based on the stereo images in the two spectral ranges.Stereoscopic representation based on stereo images in a spectral range predominantly outside of visible light can be achieved within a spectral range of visible light. Geometric calibration can include aligning the imaging areas of all image acquisition devices with each other.

[0064] Alternatively or additionally, stereo image acquisition can be performed using the first and second image acquisition units, and / or using the third and / or fourth image acquisition units. Generally, image acquisition units can be used for stereo image acquisition in any combination. For example, three, four, five, and / or six image acquisition units can be used together for stereo image acquisition. This means that stereo image acquisition does not necessarily have to be performed in the first and / or the second spectral range. For example, stereo image acquisition can be performed simultaneously in the first and second spectral ranges.

[0065] The test procedure may further include the step of coupling the test device to the medical imaging device. Coupling may, in particular, include placing and / or hooking the projection of the test device onto the imaging device and / or may further include operating the movable holding element. Furthermore, the test device may be placed against the imaging device at at least one point and pivoted about that point. After coupling, the test device is in a coupled state. In this state, the image plane of the image acquisition unit, or image acquisition devices, may preferably lie at least substantially parallel to the plane in which the optical target, in particular the calibration pattern, extends.

[0066] Furthermore, the step may include connecting a lighting device to the test device.

[0067] In addition, the lighting device can be configured to be connected to the imaging device in an imaging operating mode to provide illumination during image acquisition.

[0068] Furthermore, the overlay display can encompass the spatially adjacent sections of the first and second calibration images in such a way that the image of the calibration pattern is at least partially displayed within these adjacent sections. This allows for simple verification of the geometric calibration. Advantageously, the geometric calibration can be verified independently of the display device's resolution. This is particularly true compared to, for example, a blended display.

[0069] The verification process can further include the steps of displaying a verification aid in the calibration display, wherein the verification aid frames a verification area and thereby defines a tolerance range for the verification, moving the verification aid in the calibration display such that a first section of the image of the calibration pattern lies within the verification area, wherein the first section originates from the first calibration image, and checking whether the verification aid is movable in such a way that, in addition to the first section, a second section of the image of the calibration pattern lies within the verification area, wherein the second section originates from the second calibration image.

[0070] The verification aid can include a rectangular frame. "Rectangular" can refer to a rectangle with rounded corners. The verification area can be defined by the frame's cutout. The verification area can be viewable by a user. This means that a user views the verification area, or the frame's cutout, to assess the geometric calibration. The larger the tolerance range, the larger the frame's cutout, or the larger the verification aid, can be. Since the calibration display can show a section-by-section image of the calibration pattern, a section-by-section offset of the calibration pattern image can occur between calibration images. This offset can be smaller the more precise the geometric calibration.The offset can be so large that two sections of the calibration pattern image cannot be framed by the verification aid, where the calibration pattern image is depicted in different calibration images. For example, if the calibration pattern is a line, the line may be represented in the calibration display as two parallel, offset, dashed lines, each running along the sections of the respective calibration image. Generally, the calibration pattern image can be displayed as if it were depicted in only one calibration image, and in particular, at least substantially without offset, if the geometric calibration is ideal. Using the verification aid, the geometric calibration can be verified in at least two spatial directions.Especially when the verification aid encompasses the rectangular frame, the geometric calibration can be checked in any direction of the frame's sides. In particular, the overlay can be displayed in a checkerboard pattern. This can mean that a periodic offset of the calibration pattern can occur between the individual squares of the checkerboard, especially in two directions. The calibration pattern can, for example, form a cross extending in the two directions. For verification purposes, the verification aid can be moved using control commands. A user can initiate these control commands. For example, to check the geometric calibration, the user can use a control command to move the verification aid pixel by pixel and / or two pixels in one of the directions.The user can execute the control command as frequently as necessary until, for example, they determine that the two sections of the calibration pattern image are within the verification aid, particularly the tolerance range, and / or until they determine that the verification aid, particularly the tolerance range, cannot be moved in such a way that the two sections of the calibration pattern image are within the verification aid, particularly the tolerance range. The user can perform this, for example, in all directions of extension of the verification pattern or the image of the verification pattern. According to one embodiment, the verification pattern comprises a right-angled cross with elongated arms. By checking along the arms and / or at at least one position of each arm, the geometric calibration can be verified in two spatial directions.This method advantageously allows for very simple, fast, efficient, cost-effective, reliable, and / or effective verification of geometric calibration. In particular, this verification method is suitable for checking geometric calibration after delivery of the image acquisition unit or imaging device to a customer. For example, after delivery, the geometric calibration can be quickly and / or efficiently checked to ensure that the customer has received a sufficiently calibrated image acquisition unit. This does not require a particularly heavy, bulky, and / or difficult-to-transport test device.By creating the overlay representation and checking the representation of the image of the calibration pattern, a calibration check can be carried out in such a way that no particularly large computing power of a computing unit is necessary, whereby the computing unit is involved, for example, in creating the overlay representation.

[0071] The verification of geometric calibration can be considered successful if the verification aid is movable in such a way that, in addition to the first section, a second section of the image of the calibration pattern lies within the verification area, derived from the second calibration image. A positive result can mean that the image acquisition unit is geometrically calibrated to such an extent that a sufficiently good spatial representation of an object can be created for an application, and / or a sufficiently good superimposed representation of images of the object can be created, where the images were acquired in different spectral ranges. In particular, the evaluation may depend on the application. For some applications, particularly high image quality is necessary. In such cases, a smaller verification aid or a smaller tolerance range can be used for verification.

[0072] Furthermore, the inspection aid can extend in one spatial direction over at least 5, preferably at least 10 pixels, and in a spatial direction perpendicular to this over at least 5, preferably at least 18 pixels. Generally, the number of pixels can be closely related to the pixel size, the resolution of the display, the image sensor used, and / or the required size of the tolerance range and / or the inspection aid.

[0073] The testing procedure can also include further verification steps, for which the verification aid is moved to different image areas of the calibration display. Different image areas can refer to areas between which several, for example, at least two, three, four, five, and / or six of the verification aids would fit. The image areas can be spaced apart from each other. For example, the image areas can be moved to different edge regions of the calibration display. This allows, for instance, an assessment of the homogeneity of the geometric calibration across the entire imaging area of ​​the image acquisition devices. Furthermore, distortion of the images from the image acquisition devices can be verified.

[0074] Furthermore, at least one verification procedure can be performed in a central area of ​​the calibration representation, and further verification procedures can be performed in a central area of ​​each of the quadrants of the calibration representation. The calibration representation can be rectangular. At least one rectangular calibration representation can be divisible into four areas of at least essentially equal size, particularly rectangular ones. These areas can be the quadrants. This allows for a simple and reproducible verification of the geometric calibration in multiple areas of the calibration representation. The calibration pattern can be designed such that it includes at least one sub-pattern which, when depicted, can be represented in the central area of ​​the calibration representation.

[0075] Furthermore, the test procedure can include a step of generating a magnified representation of a section of the calibration representation, such that central areas of each quadrant of the calibration representation are displayed in a corner of the magnified representation. This can mean that the magnified representation can be generated by 2x magnification or 2x zoom of the calibration representation. In the magnified representation, the geometric calibration in the center and / or corners of the magnified representation can be checked and / or verified. This allows the center of each quadrant to be located easily and quickly, and / or the geometric calibration in the central areas of the quadrants of the calibration representation to be verified. The test procedure can thus be carried out more efficiently and reliably.

[0076] The inspection procedure may further include a preparation step. This preparation step may consist of the following: capturing an image of the optical target with one of the image acquisition devices; generating a representation of the target based on the captured image; displaying an alignment aid for aligning the optical target relative to the image acquisition unit; and aligning the optical target with the alignment aid by moving the target. The preparation step may be executable and / or performed before at least one inspection step. Furthermore, the preparation step may be executable and / or performed before at least substantially every inspection step. The alignment aid can simplify the positioning of the optical target.For example, the optical target can be more easily positioned at a location where it can be imaged in such a way that it can be represented at a desired location in the calibration image. The desired location can, in particular, be the center of the calibration image. This can mean that the alignment aid can mark and / or point to the center of the calibration image.

[0077] This allows the testing procedure to be applied quickly and / or easily to various image acquisition devices. Furthermore, it can compensate for, for example, movement of the target during the execution of a testing procedure.

[0078] Furthermore, the calibration pattern can comprise a central rectangular cross with elongated arms, and the alignment aid can also comprise a rectangular cross with elongated arms. Two patterns that are at least substantially similar in shape and / or design can be compared in a particularly simple manner. For example, the degree of overlap between the representations of both patterns can be easily compared, and / or the quality of the alignment can be assessed based on the degree of overlap. A high degree of overlap can indicate good alignment. According to other embodiments, the alignment aid can, for example, comprise a frame within which the image of the optical target is to be positioned, at least substantially.

[0079] The image acquisition unit can further comprise at least one additional image acquisition device, and the image acquisition devices can have a common geometric calibration with respect to their imaging ranges. The test procedure can further comprise pairwise verification of the calibration of the image acquisition devices. Pairwise verification of the image acquisition devices can achieve high quality in spatial representation and / or superimposition. For example, one pair of image acquisition devices can be configured for stereo imaging and / or another pair for stereo fluorescence imaging in the near-infrared spectral range. The geometric calibration of all these image acquisition devices can be verified pairwise. This pairwise verification can be performed sequentially. The geometric calibration of multiple image acquisition devices can be verified in a simple and efficient manner.

[0080] The present invention may further provide a system for carrying out a testing procedure. In some embodiments, the system may enable the testing to be carried out automatically and / or semi-automatically.

[0081] The present invention may further provide for the provision of program code comprising instructions which, when executed by a processor, effect the performance of a test method according to the invention.

[0082] The present invention may further provide for a computer program product comprising a machine-readable medium on which program code according to the invention is stored.

[0083] The invention is explained below by way of example with reference to figures. The drawing, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and use them meaningfully in combination within the scope of the claims.

[0084] If more than one instance of a particular object exists, only one of them may be identified with a reference symbol in the figures and description. The description of this instance can then be applied to the other instances of the object. If objects are named using numerical terms, such as first, second, third object, etc., these serve to identify and / or classify objects. Thus, for example, a first object and a third object, but not a second object, may be included. However, numerical terms could also indicate a number and / or sequence of objects.

[0085] They show: Fig. 1. A schematic representation of a system; Fig. 2A a schematic representation of an image acquisition unit of the system in a side view; Fig. 2B a schematic representation of the image acquisition unit in a top view; Fig. 2C a schematic representation of the image acquisition unit in a view of the back of the image acquisition unit; Fig. 3 a perspective view of a test device of the system and the image acquisition unit; Fig. 4 a perspective sectional view of a section of the test device; Fig. 5 a representation of a section of the test device at the distal end of a holder; Fig. 6 a perspective view of a section of the test device at the proximal end; Fig. 7 a schematic representation of the operating principle of the test device; Fig. 8 an exemplary schematic representation of an intensity distribution; Fig. 9 a schematic cross-sectional view of an optical target; Fig. 10 an embodiment of a calibration pattern; Fig. 11 a calibration image comprising an image of a calibration pattern and an alignment aid; Fig. 12 a calibration representation based on a first calibration image and a second calibration image; Fig. 13 a review aid; Fig. 14 a schematic representation of an enlarged view of the calibration representation comprising an overlay of the verification aid and the image of the calibration pattern; Fig. 15 a section of the calibration representation, based on which the geometric calibration is positively evaluated; Fig. 16 a section of the calibration representation, based on which the geometric calibration is negatively assessed; Fig. 17 another embodiment of a superimposed representation; Fig. 18 a schematic flowchart comprising several steps of a testing procedure; Fig. 19 a schematic flowchart comprising several steps of a review process; and Fig. 20 a schematic flowchart encompassing several steps of a preparation process.

[0086] Fig. Figure 1 shows a schematic representation of the system 100. The system 100 comprises an image acquisition unit 64, a testing device 10, a lighting device 74, a display device 78, and an input device 86. Some of the components, in this case the lighting device 74, the display device 78, and the input device 86, are arranged on a cart 124. The cart 124 has casters, allowing it to be moved around the room. For example, a user can move the cart 124 to a deployment location for the image acquisition unit 64.

[0087] The image acquisition unit 64 is detachably attached to a movable support arm 122. The image acquisition unit 64 can be interchangeable with another image acquisition unit (not shown). Furthermore, the image acquisition unit 64 can be positioned in space in all three spatial directions using the support arm 122. The user can, for example, position the image acquisition unit 64 so that an image of an object, such as an area of ​​investigation, can be captured to support an action. Alternatively, a sequence of images, such as a video, can be captured. A display of the image and / or video can be shown on the display device 78. The user can therefore view the display of the image and / or video on the display device 78 while performing an action.

[0088] Furthermore, the image acquisition unit 64 is equipped for stereo imaging. For this purpose, the image acquisition unit 64 comprises several image acquisition devices 66, 68, 88, 90, 114. A more detailed schematic representation of the image acquisition unit 64 is shown in the Fig. 2A and Fig. Figure 2B shows that stereo imaging can be used to generate a spatial representation. This representation is based on at least two images from two image acquisition units 66, 68, 88, 90, 114. The image acquisition unit 64 is fundamentally configured to acquire images in a first spectral range 70, which is predominantly within the spectral range of visible light. Furthermore, the image acquisition unit 64 is configured to acquire images in a second spectral range 72, which is at least predominantly outside the spectral range of visible light. The image acquisition unit 64 is also configured for stereo imaging in the second spectral range 72. A spatial representation of the images from both spectral ranges 70 and 72 can be displayed together in a spatial superposition representation (not shown).In particular, the second spectral range 72 can include a second wavelength 18, wherein the second wavelength 18 comprises a wavelength from the infrared range, especially from the near-infrared range. This can, for example, enable luminescence imaging, especially fluorescence imaging and / or phosphorescence imaging. A structure to be investigated within the investigation area can be stained, for example, by means of a fluorescent dye which absorbs first light, especially first illumination light, comprising a first wavelength 16, and emits light comprising the second wavelength 18. The first wavelength 16 is to be assigned to the spectral range of visible light, or the first light, especially the first illumination light, comprises at least predominantly light from the visible range.Consequently, the spatial overlay representation allows the structure under investigation to be located more precisely and / or made visible.

[0089] The image acquisition unit 64 further comprises a light supply connection 126. A light guide 44 of the illumination device 74 can be connected to the light supply connection 126. The illumination device 74 is configured to generate and / or provide the initial illumination. That is, the illumination device 74 is configured to generate predominantly visible light. In particular, in an imaging operating mode, the illumination device 74 is connected to the imaging device 26, especially to the image acquisition unit 64, to provide illumination during image acquisition. In a calibration mode, the illumination device 74 is connected to the test device 10. In the calibration mode, the geometric calibration of the image acquisition unit 64 is verified.Only one lighting device 74 is clearly provided for operating the test device 10 and the imaging device 26. The imaging device 26 is usually operated with lighting devices such as the lighting device 74, so such a lighting device is already present when the imaging device 26 is operated.

[0090] The optical fiber 44 can be connected to the test device 10, in particular to an optical fiber connection 42 of the test device 10. In the illustrated case, the optical fiber 44 is connected to the test device 10 so that the first illumination light, which is guided in the optical fiber 44, can be coupled into and / or is coupled into the test device 10. The test device 10 is coupled to the imaging device 26, in particular the image acquisition unit 64, by means of a holder 24 of the test device 10. In particular, the test device 10 is connected to an input optic (see Fig. 2A and Fig. 2B) the image acquisition unit 64 is coupled. This allows at least one image of an object within the test device 10 to be captured and / or acquired by means of the image acquisition unit 64. According to the illustrated embodiment, at least one image of an optical target 20 is captured. The optical target 20 is at least partially illuminated by light provided by the illumination device 74.

[0091] The image acquisition unit 64, in particular the image acquisition devices 66, 68, 88, 90, 114, have geometric calibration with respect to their imaging ranges. As described in more detail in the following figures, the image acquisition unit 64 is configured to acquire calibration images 22 of the optical target 20, and the geometric calibration of the image acquisition unit 64 can be verified using the calibration images 22. An embodiment of a test device 10 is shown in more detail in the following figures. Furthermore, the following figures illustrate how the test device can be operated, for example.

[0092] Captured images, such as calibration images 22, can be displayed on the display device 78. Or rather, the images are displayed on the display device 78. For example, in the Fig. 1 The display device 78 represents the calibration display 80 for a user, wherein the calibration display 80 is based on the calibration images 22. The calibration display 80 comprises a superimposed display 82, which includes spatially adjacent sections 84 of the calibration images 22. The sections 84 alternately originate from one of the calibration images 22. More precisely, the superimposed display 82 comprises multiple sections of one of the calibration images 22 arranged alternately in two different spatial directions. The superimposed display 82 is at least in the Fig. 11 shown in more detail. In the imaging operating mode, for example, spatial representations, in particular spatial superimposition representations, are displayed on the display device 78.

[0093] Using the input device 86, the user can, for example, initiate control commands to check the calibration of the image acquisition unit 64. Furthermore, the input device 86 can be used, for example, to control the medical imaging device 26, in particular the image acquisition unit 64. The input device 86 can be connected to the imaging device 26, in particular the image acquisition unit 64, as shown in the Fig. 1 is shown.

[0094] The Fig. 2A, Fig. 2B and Fig. Figures 2C show a schematic representation of the image acquisition unit 64 of the medical imaging device 26 of the system 100 in different views. Fig. Figure 2A shows a schematic representation of the image acquisition unit in a side view. Fig. 2B a schematic representation of the image acquisition unit 64 in a top view and Fig. Figure 2C shows a schematic representation of the image acquisition unit 64 in a view of the rear of the image acquisition unit 64. The image acquisition unit 64 comprises several image acquisition devices 66, 68, 88, 90, 114. The image acquisition devices 66, 68, 88, 90, 114 are jointly enclosed by the housing 128. The image acquisition unit 64 also includes an input optic 130, by means of which light can be coupled into the image acquisition unit 64 for the image acquisition devices 66, 68, 88, 90, 114. The image acquisition devices 66, 68, 88, 90, 114 have at least substantially the same optical properties. This means, for example, that they have at least substantially a common imaging area. The image acquisition unit 64 exhibits the geometric calibration of the first image acquisition units 66, 68, 88, 90, 114 with respect to their imaging ranges. This means that the imaging ranges are at least substantially the same.Furthermore, the better the geometric calibration, the more congruent the image areas. If, for example, an object is captured using images from different image acquisition devices 66, 68, 88, 90, 114, the object may have been captured at slightly different coordinates depending on the geometric calibration. This means that an offset can occur between images of the object captured by different image acquisition devices 66, 68, 88, 90, 114. The offset is smaller the better the geometric calibration. This is particularly important because the image acquisition unit 64 and / or the medical imaging device 26 are intended to capture spatial representations of an examination area. A minimal offset is desirable to ensure the highest possible quality of the spatial representation.Furthermore, various spatial representations, which can be based on images from different spectral ranges, can be superimposed. The image acquisition devices 66, 68, 88, 90, 114 are thus configured for stereo image acquisition. This results in pairs of image acquisition devices 66, 68, 88, 90, 114.

[0095] The image acquisition unit 64 comprises a first image acquisition device 66 and a second image acquisition device 88, each of which is light-sensitive in the first spectral range 70. Furthermore, the acquisition unit 64 comprises a second image acquisition device 68 and a fourth image acquisition device 90, each of which is light-sensitive in the second spectral range 72. At least one of the third and fourth image acquisition devices 88, 90 can also be referred to as a further image acquisition device 114. Stereo image acquisition in the first spectral range 70 is possible using the first image acquisition device 66 and the third image acquisition device 88. Stereo image acquisition in the second spectral range 72 is possible using the second image acquisition device 68 and the fourth image acquisition device 90. In particular, the second spectral range 72 lies in the near-infrared range.This makes it possible to perform fluorescence stereo image acquisition using the second image acquisition device 68 and the fourth image acquisition device 90.

[0096] The image acquisition devices 66, 68, 88, 90, and 114 each comprise an image sensor 132 and 134, respectively, which are light-sensitive in different spectral ranges. The first image acquisition device 66 and the second image acquisition device 88 each comprise a first image sensor 132 that is light-sensitive at least predominantly in the first spectral range 70, which corresponds to the spectral range of visible light. This means that image acquisition in the wavelength range of visible light is possible using the first image sensor 132. This corresponds approximately to conventional image acquisition. Image acquisition in the wavelength range of near-infrared light is possible using the second image sensor 134. This enables fluorescence imaging. The second image acquisition device 68 and the fourth image acquisition device 90 each comprise a second image sensor 134.Since the second image sensor 134 is at least predominantly light-sensitive in the second spectral range 72 and, in particular, is relatively light-insensitive in the wavelength range of visible light, light in both spectral ranges 70 and 72 must be provided to verify the geometric calibration of the image acquisition unit 64. To verify the geometric calibration, the image acquisition unit 64 acquires the calibration images 22 of the optical target 20. In particular, each of the image acquisition devices 66, 68, 88, 90, and 114 acquires at least one calibration image 22 of the optical target 20. Using the calibration images 22, the user can, for example, verify the geometric calibration of the image acquisition unit 64. It is specifically intended that the geometric calibration of the image acquisition devices 66, 68, 88, 90, and 114 is verified in pairs.This means that, in particular, the geometric calibration of an image acquisition unit 68, 90, which is light-sensitive in the second spectral range 72 (near-infrared), and an image acquisition unit 66, 88, which is light-sensitive in the first spectral range 70 (visible light), is provided. For this purpose, it is necessary that near-infrared light, comprising the second wavelength 18, and visible light, in particular white light, comprising the first wavelength 16, be supplied and / or that the optical target 20 be illuminated with this light. This allows calibration images 22 to be acquired in both spectral ranges 70, 72, and enables the generation of superimposed images 82 based on images acquired in both spectral ranges 70, 72.By means of the conversion element 14, light can be provided in both spectral ranges 70, 72, although the system only comprises a lighting device 74 which provides and / or generates at least predominantly light in the first spectral range 70 (visible light).

[0097] The test device 10 is in the Fig. 3 and Fig. 4 shown in more detail. Fig. Figure 3 shows a perspective view of the test device 10 and the image acquisition unit 64. Fig. Figure 4 shows a perspective sectional view of a section of the test device 10.

[0098] The test device 10 comprises the light guide connection 42, a light supply 12, the optical target 20, a conversion element 14, and the holder 24. The light guide 44 of the illumination device 74 can be connected to the light guide connection 42 such that the first illumination light guided in the light guide 44 can be coupled into the test device 10, in particular into the light supply 12. The light guide connection 42 can be any standard light guide connection. In particular, the light guide connection 42 can include a clamping device 156 by means of which the light guide 44 can be clamped to it. See also Fig. 6. Fig. Figure 6 shows a perspective view of a section of the test device 10 at the proximal end 46, comprising the light guide connection 42, the clamping device 156, the light guide 44, and the screen 38. The first illumination light is guided by means of the light supply 12. In particular, the first illumination light is guided onto the conversion element 14. The light supply 12 includes a reflective screen 38, which is configured to guide light from the first illumination light to the conversion element 14. The screen 38 has a reflective coating on at least a large part of its inner surface. In addition, the screen 38 has a cross-sectional area 40 that increases in the direction of the conversion element 14. The screen is funnel-shaped and has openings at its proximal end 46 and at its distal end 49.The optical fiber connection 42 is located at the proximal end 46, and a diffusion element 52 and the conversion element 14 are located at the distal end 49. The screen 38 has a first cross-sectional area 48 at the proximal end 46 and a second cross-sectional area 50 at the distal end 49, the second cross-sectional area 50 being larger than the first cross-sectional area 48. This directs light, particularly the initial illumination light coupled to the proximal end 46, onto a larger cross-sectional area 40. This allows planar elements to be illuminated. Light, especially the initial illumination light, strikes the diffusion element 52 at the distal end 49. The diffusion element 52 homogenizes and diffuses the light. This results in more uniform illumination of the conversion element 14 and consequently improves image acquisition quality.The diffusion element 52 is a milky Plexiglas plate that is at least as large as the second cross-sectional area 50.

[0099] The conversion element 14 is also plate-shaped and rests on the diffusion element 52. The function of the conversion element 14 is described by the Fig. 7 and Fig. Section 8 explains this in more detail. Basically, the conversion element 14 is configured to convert light, in particular the first illumination light, with the first wavelength 16, at least partially into light, in particular the second illumination light, with the second wavelength 18, wherein the first wavelength 16 and the second wavelength 18 are different. The second wavelength 18 comprises a wavelength from the near-infrared range. The first wavelength 16 comprises a wavelength from the visible range. The first illumination light comprises at least predominantly light from the visible range. The conversion element 14 is configured to convert light from the visible range at least partially into light from the infrared range. For this purpose, the conversion element 14 exhibits fluorescent properties.The conversion element 14 is designed as a fluorescent Plexiglas plate and is covered on both main sides, i.e., sides that are illuminated and / or from which light is at least predominantly emitted, particularly in the direction of the optical target 20, with a matte film. The matte film enables homogeneous emission in the direction of the optical target 20 and allows for more efficient coupling of the infrared radiation.

[0100] The conversion element 14 is approximately the same size as the diffusion element 52. Both elements 14 and 52 are inserted together into a receiving slot 142 of the test device 10, specifically into the light path of the light with the first wavelength 16, particularly the first illumination light. If necessary, further elements can be inserted into the receiving slot 142 and / or at least one of the elements 14 or 52 can be replaced. For this purpose, the test device 10 includes a detachably fastenable cover plate 144, which can be secured by means of screws. The cover plate 144 is arranged on a lateral side of the test device 10, specifically of the screen 38.

[0101] The optical target 20 is arranged at a distance from the conversion element 14 and is also plate-shaped. The distance can be, for example, 1 cm to 20 cm, in particular 2 cm to 10 cm, preferably 3 cm to 8 cm. Furthermore, the optical target 20 is movably mounted. For this purpose, the optical target 20 comprises two handles 138 on two opposite sides. The optical target 20 also has a smaller surface area than the conversion element 14, so that the main surface of the optical target 20, which is illuminated in particular by means of illumination light, is movable parallel to the main surface of the conversion element 14, from which light comprising the first wavelength 16 and the second wavelength 18 is emitted. This allows the calibration pattern 54 of the optical target 20 to be aligned with respect to the image acquisition unit 64, in particular the image acquisition devices 66, 68, 88, 90, 114.The optical target 20 is mounted in a bearing device 136. The bearing device 136 is a sliding bearing device and is slot-shaped. A rubber lining 140 of the bearing device 136 is in contact with the optical target 20. The rubber lining 140 is provided on all side walls 148 into which the bearing device 136 is slotted. The side walls 148 define a cavity 150 in which light of the first illumination light and the second illumination light and / or light comprising the first wavelength 16 and / or the second wavelength 18 is guided. The handles 138 are removable so that, when at least one of the handles 138 is removed, the optical target 20 can be inserted into the bearing device 136. The optical target 20 comprises two glass plates 152, in the center of which a film 154 is arranged, on which the calibration pattern 54 is provided and / or which comprises the calibration pattern 54. See also . Fig. 9. Fig. Figure 9 shows a schematic sectional view of the optical target 20. The glass plates 152 serve to protect the film 154 from damage and / or to facilitate the handling of the film 154, in particular the calibration pattern 54. Alternatively or additionally, the calibration pattern 54 can be provided directly on the conversion element 14 and / or the optical target 20 can be integrated with the conversion element 14 (not shown).

[0102] The bracket 24 extends distally from the side walls 148. The bracket 24 is designed to be particularly lightweight and / or mass-optimized. The bracket 24 comprises a spacer 28 and a coupling section 32. The spacer 28, and in particular the bracket 24, extends only on two sides and / or has recesses 146. This allows for weight savings. The recesses 146 can be cut and / or milled from aluminum plates. The coupling section 32 is arranged at a distal end of the spacer 28. At this distal end, in particular by means of the coupling section 32, the test device 10 is coupled to the image acquisition unit 64. The bracket 24 is designed to support the weight of the test device 10 in the coupled state shown. This means that the test device 10 is merely attached to the image acquisition unit 64 and is held and / or supported by it.The spacer 28 defines a distance 30 between the imaging device 26, in particular the image acquisition unit 64, and the optical target 20. This allows the distance 30 to be predicted reliably and repeatably.

[0103] The coupling section 32 is in the Fig. 5 shown in more detail. Fig. Figure 5 shows a representation of a section of the test device 10 at the distal end of the holder 24. Furthermore, the Fig. Figure 5 shows a holding section 156 of the image acquisition unit 64. To couple the test device 10, the test device 10 is attached to the holding section 156 by means of the coupling section 32. The test device 10, in particular the coupling section 32, comprises a projection 34 which is configured to hold the test device 10 by engaging behind it. The projection 34 engages behind a section of the holding section 156 of the image acquisition unit 64. The holding section 156 may, for example, include a circumferential groove 158, which is rounded in shape. Furthermore, the test device 10, in particular the coupling section 32, comprises a movable retaining element 36 which is configured to selectively fix the holder 24 to the medical imaging device 26 to be tested. In this case, the retaining element 36 is designed as a rotatable fixing screw which is rotatable in a thread provided on the coupling section 32.By turning the screw, the test fixture 10 is fixed and / or clamped to the imaging device 20. In particular, the retaining section 156 is clamped between the projection 32 and the retaining element 36. To couple the devices, the user can first insert the projection 32 into the circumferential groove 158 so that the projection 32 partially engages behind the retaining section, and then rotate the test fixture 10 around the projection 32 while the projection remains in contact with the retaining section. This allows the user to move the retaining element 36 towards the retaining section 156. In the correct position, which is adjustable as needed, the user can fix the test fixture by operating the movable retaining element 36. The projection 32 and the retaining section 156 can form a dovetail-like connection.

[0104] In general, the test device 10 is compact and easy to handle. It weighs, for example, between 0.1 kg and 20 kg, in particular between 1 kg and 10 kg, preferably between 2 kg and 5 kg. Furthermore, its length between the fiber optic connection 42 and the coupling section 32 is, for example, between 0.1 m and 2 m, in particular between 0.2 m and 1.3 m, preferably between 0.3 m and 0.8 m. In particular, the test device 10 is shorter than the image acquisition unit 64. Furthermore, the test device 10 is made, at least predominantly, and in particular a frame of the test device 10, of aluminum and / or a plastic. In particular, the material is easily cleanable, disinfectable, and / or autoclavable.

[0105] The Fig. Figure 7 shows a schematic representation of the operating principle of the test device 10. Light in the first spectral range 70, comprising the first wavelength 16, in particular the first illumination light, is provided and directed onto the conversion element 14. The conversion element 14 transmits this light at least partially. In addition, the conversion element 14 converts light with the first wavelength 16, in particular the first illumination light, into light in the second spectral range 72, comprising the second wavelength 18, in particular the second illumination light. This is shown in the Fig. 8. This is shown in more detail using an exemplary schematic representation of an intensity distribution. This shows the intensity I plotted against the wavelength A. It is understood that the intensity distribution shown is not based on an actual measurement of an emission spectrum of the illumination device 74 and / or the conversion element 14. The distribution is to be understood as an example and serves only to explain the operating principle in more detail. Actual emission spectra can sometimes deviate significantly from the intensity distribution shown. Fig. Figure 8 shows a diagram with wavelength plotted on the abscissa 160 and light intensity plotted on the ordinate 162. A first distribution 168 of the first illumination light is shown as a solid line, and a second distribution 170 of the second illumination light is shown as a dashed line. The first distribution 168 lies predominantly within the first spectral range 70 and includes the first wavelength 16, which is also located within the first spectral range 70. The second distribution 170 lies predominantly within the second spectral range 72 and includes the second wavelength 18, which is also located within the second spectral range 72. The first spectral range 70 corresponds to the wavelength range of visible light 164, approximately between 380 nm and 780 nm.The second spectral range 72 corresponds to the wavelength range of near-infrared light 166, approximately between 780 nm and 3000 nm. The conversion element 14 converts the light with the first wavelength 16, at least partially, into light with the second wavelength 18 by means of fluorescence and / or phosphorescence, in particular luminescence. Consequently, the conversion element 14 converts light of the visible range 164 into light of the near-infrared range 166. Therefore, by providing the conversion element 14, it is not necessary to provide a lighting device that predominantly emits light in the wavelength range of near-infrared light 166. The conversion element 14 can comprise several elements that convert light by means of luminescence. This allows for a broader second distribution 170 encompassing multiple wavelength peaks.

[0106] Returning to the Fig. As can be seen in Figure 7, after the light passes through the conversion element 14 in the first spectral range 70, light is present in both the first spectral range 70 and the second spectral range 72. This light is directed to illuminate the optical target 20. Consequently, at least one calibration image 22 can be acquired by the image acquisition unit 64. Preferably, at least one calibration image 22 is acquired by each of the image acquisition devices 66, 68, 88, 90. This means that calibration images 22 are acquired in the spectral range of visible light and near-infrared light. The geometric calibration of the image acquisition unit 64 can be verified using the calibration images 22. In particular, the optical target 20 comprises the calibration pattern 54, and at least one image of the calibration pattern 54 is acquired by the image acquisition unit 64.The image of the calibration pattern 54 can extend, for example, section by section, over various calibration images 22, as will be shown below. The geometric calibration can be verified using the image of the calibration pattern 54 in the superimposed representation 82.

[0107] The Fig. Figure 10 shows an embodiment of the calibration pattern 54. The calibration pattern 54 comprises a line 56 and / or a cross 58. The calibration pattern 54 includes a central rectangular cross 59 with elongated arms 60, the center of which can be aligned with the center of the calibration image 22, and which divides the calibration image 22 into four quadrants 62. See also Fig. 11 and Fig. 12. In each of the four quadrants 62, another right-angled cross 58 with elongated arms 60 is arranged, the center of each of which is located in a central area of ​​the corresponding quadrant 62. Although the calibration image 22 is divided into four quadrants 62, the calibration pattern 54 can also be divided into the four quadrants 62 for the sake of simplicity. The calibration pattern 54 is located in a central area of ​​the optical target 20. The calibration pattern 54 comprises elongated pattern segments (e.g., the line 56 and / or the elongated arms 60). These can be used to check for an offset of the image of the calibration pattern 54 in the superimposed representation 82. If the offset is too large, the geometric calibration is insufficient.

[0108] Before performing the geometric calibration check, the optical target 20, in particular the calibration pattern 54, can be aligned relative to the image acquisition unit 64, in particular the input optics 130. For this purpose, the user grasps the optical target 20 by the handles 138 and aligns the calibration pattern 54 using an alignment aid 92. See also Fig. 11. In the Fig. Figure 11 shows a representation of a calibration image 22, comprising an image of the calibration pattern 172 and the alignment aid 92. The representation is displayed on the display device 78 during alignment. That is, the display device 78 is configured to display the alignment aid 92. The calibration image 22 is acquired by only one of the image acquisition devices 66, 68, 88, or 90. In particular, a sequence of calibration images 22, especially a video, is displayed during alignment. When the user moves the calibration pattern 54, they can view the representation on the display device 78. This allows them to see how the calibration pattern 54 is positioned relative to the alignment aid 92. In a good alignment, the image of the central cross 59 and the alignment aid 92 are shown to be at least predominantly overlapping.In this orientation, the image of the calibration pattern 172, in particular the central cross 59, is positioned at least substantially in the center of the calibration images 22. Thus, the image of the cross 59 also passes through the center of the superimposed representation 82. In the example shown, the alignment aid 92 comprises a central cross with elongated arms.

[0109] Fig. Figure 12 shows the calibration representation 80, which is based on a first calibration image 180 and a second calibration image 182. The calibration representation 80 is divided into four quadrants 62. The display device 78 is configured to show the calibration representation 80, based on the calibration images 22, 180, and 182, to the user. The first calibration image 180 was acquired by the first image acquisition unit 66, and the second calibration image 182 by the second image acquisition unit 68. The calibration images 180 and 182 were therefore acquired in different spectral ranges. The calibration representation 80 includes the superimposed representation 82. The superimposed representation 82 is arranged like a chessboard 169. This means that the superimposed representation 82 comprises multiple sections 84 of the first calibration image 180 and the second calibration image 182 arranged alternately side by side in two different spatial directions.Sections 84 of the first and second calibration images 180 and 182 are each offset by an entire section 84 in successive rows of the chessboard 169. The superimposed image 82 comprises section-by-section image segments from various image acquisition devices 66 and 68, which were combined to form the superimposed image 82. As in the... Fig. As can be seen in Figure 14, an image of the calibration pattern 54 can also be assembled from sections 84. However, since sections 84 originate from images of different image acquisition devices 66, 68, which may depict the optical target 20, in particular the calibration pattern 54, slightly differently, an offset 184 can occur between sections of the image of the calibration pattern 54. The offset 184 is a measure of the quality of the geometric calibration. The offset 184 is smaller when the geometric calibration is better.

[0110] The calibration display 80 comprises different image areas 106 in which the geometric calibration is checked. A verification aid 94 can be used for this purpose (see Fig. 13, Fig. 14, Fig. 15, Fig. 16) are moved into the image areas 106. In each of the image areas 106, a verification sequence is then performed to check the geometric calibration. First, a verification sequence is performed in a central area 108 of the calibration representation 80. Then, further verification sequences are performed in a central area 110 of each of the quadrants 62 of the calibration representation 80.

[0111] To carry out a test procedure, in particular the verification process, a magnified representation 112 (see Fig. 14) are generated. The magnified representation 112 is based on a section 113 of the calibration representation 80. Using the magnified representation 112, the user can more easily perform the verification process, in particular better estimate the size of the offset 184. In the magnified representation 112, central areas 110 of the quadrants 62 of the calibration representation 80 are each shown in a region of a corner of the magnified representation 112. This means that the magnified representation 112 includes an image of the cross 58 of the calibration pattern 54 in each of the corner regions. Thus, the geometric calibration can be checked in five regions in the magnified representation 112.

[0112] The Fig. Figure 13 shows, as an example, the verification aid 94. The verification aid 94 frames a verification area 94 and thereby defines a tolerance range 98 for the verification of the geometric calibration. The verification aid 94 includes a verification frame 99, which defines a boundary area of ​​the verification aid 94. The cutout 101 of the frame 99 defines the tolerance range 98. In the Fig. Figure 13 shows tiles. Each tile corresponds to a pixel 174. The tiles are not to be confused with the squares of the chessboard 169. Each square of the chessboard 169 comprises several pixels 174. The frame is 4 pixels wide. The width can be varied depending on the pixel size and / or resolution of the display device 78. The frame should be clearly visible to the user. The inspection aid 94, in particular the tolerance range 98, extends in one spatial direction over at least 5, preferably at least 10 pixels, and in a spatial direction perpendicular to it over at least 5, preferably at least 18 pixels.

[0113] The Fig. Figure 14 shows a schematic representation of the magnified representation 112 of the calibration representation 80, in particular the superimposed representation 82 and / or the checkerboard 169, comprising an overlay of the verification aid 94 and the image of the calibration pattern 172. The sections 84 of the respective calibration images 22 used for the superimposed representation 82, in particular the first calibration image 180 and the second calibration image 182, at least partially depict the calibration pattern 54. This can mean that the representation includes the superimposed representation 82 and the image 172 of the calibration pattern 54. The spatially adjacent sections 84 of the first calibration image 180 and the second calibration image 182 are encompassed in such a way that the image 172 of the calibration pattern 54 is shown section by section in the spatially adjacent sections 84 of the first calibration image 180 and the second calibration image 182.This results in the offset 184 of image 172 of calibration pattern 54 between sections 84. With a theoretically ideal geometric calibration, the offset 184 is no longer discernible and / or at least essentially non-existent. In the example shown, calibration pattern 54 includes the central cross 59, and the magnified representation 112 shows an image of the cross 59 with a section-by-section offset 184. Furthermore, offset images of the crosses 58 are visible in the corner areas of the magnified representation 112. The geometric calibration can be checked wherever an offset 184 is visible in the representation 112.

[0114] For this purpose, the verification aid 94 is displayed in the calibration display 80. The verification aid 94 is then moved within the calibration display 80 such that a first section 102 of the image of the calibration pattern 54 lies within the verification area 96, with the first section 102 originating from the first calibration image 180. It is then checked whether the verification aid 94 can be moved such that, in addition to the first section 102, a second section 104 of the image of the calibration pattern 54 lies within the verification area 96, with the second section 104 originating from the second calibration image 182. The verification of the geometric calibration is considered successful if the verification aid 94 can be moved such that, in addition to the first section 102, the second section 104 of the image of the calibration pattern 54, originating from the second calibration image 182, lies within the verification area 96.The user can perform the check by means of control commands initiated via the input device 86. He can move the check aid, for example, pixel by pixel to the right or left, up or down, to perform the check. Alternatively or additionally, a system 120 can be provided (see ). Fig. 1) by means of which the verification and / or a test procedure can be carried out semi-automatically and / or automatically. A positive evaluation of the geometric calibration means that a spatial representation using the image acquisition devices 66, 68, 88, 90 has sufficiently good quality. In addition, a fluorescence image representation can be superimposed on the spatial representation with sufficient goodness.

[0115] In the Fig. Figure 15 shows an example, based on a section of the calibration representation 80, where the geometric calibration is positively evaluated. In the Fig. Figure 16 shows an example using a section of the calibration representation 80, in which the geometric calibration is negatively evaluated.

[0116] According to the Fig. 15. The verification aid 94 can be moved such that, in addition to the first section 102, the second section 104 of image 172 of calibration pattern 54 lies within the verification area 96, wherein the first section 102 originates from the first calibration image 180 and the second section 104 from the second calibration image 182. Sections 102 and 104 are therefore within the tolerance range 98.

[0117] According to the Fig. 16. The verification aid 94 cannot be moved in such a way that, in addition to the first section 102, the second section 104 of image 172 of calibration pattern 54 lies within the verification area 96, where the first section 102 originates from the first calibration image 180 and the second section 104 from the second calibration image 182. Sections 102 and 104 are therefore outside the tolerance area 98.

[0118] In the Fig. Figure 17 shows a further embodiment of a superimposed representation 82' of a calibration representation 80' in a schematic diagram. Most of the features correspond to those of the calibration representation 80. Therefore, the focus is primarily on the differences. The superimposed representation 82' comprises a blended representation 225. The calibration representation 80', in particular the superimposed representation 82' and / or the blended representation 225, is based on the first calibration image 180 and the second calibration image 182. The first calibration image 180 and the second calibration image 182 each comprise an image 172 of the calibration pattern 54. The second calibration image 182 is shown as semi-transparent and superimposed on the first calibration image. Thus, an offset 184 can be seen along a line of the images 172 of the calibration pattern 54. The geometric calibration can be verified using this offset 184.Furthermore, the displayed verification aid 94 can be seen in the calibration display 80'. The verification aid 94 can be moved in the calibration display 80 such that a first section 102' of the image of the calibration pattern 54 lies within the verification area 96, wherein the first section 102' originates from the first calibration image 180. Using the verification aid, it can be checked whether, in addition to the first section 102', a second section 104' of the image 172 of the calibration pattern 54 can be arranged within the verification area 96, wherein the second section 104' originates from the second calibration image 182.

[0119] The Fig. Figure 18 shows a schematic flowchart encompassing several steps of a test procedure. The test procedure can be carried out using the test device 10 and / or the system 100 and comprises the following steps: a step 201 of generating the first illumination light, which includes light with the first wavelength 16; a step 202 of generating the second illumination light, which includes light with the second wavelength 18 different from the first wavelength 16; a step 203 of supplying the first illumination light and the second illumination light to the optical target 20 for its illumination; a step 204 of capturing the calibration images 22 of the target 20 by means of the medical imaging device 26 with the image acquisition unit 64, wherein the image acquisition unit 64 comprises the first image acquisition device 66, which is photosensitive in the first spectral range 70, which includes the first wavelength 16, and the second image acquisition device 68, which is photosensitive in the second spectral range 72, which is different from the first spectral range 70 and includes the second wavelength 18, wherein the image acquisition unit 64 has the geometric calibration of the first image acquisition device 66 and the second image acquisition device 68 with respect to their imaging ranges; and A step 205 of checking 205 the geometric calibration of the image acquisition unit 64 using the calibration images 22 of the optical target 20. Generating 202 the second illumination light comprises converting light from the first illumination light with the first wavelength 16 at least partially into second illumination light with the second wavelength 18, which differs from the first wavelength 16. The test procedure may include at least one further step 206.

[0120] The Fig. Figure 19 shows a schematic flowchart encompassing several steps of a review process. The review process includes the following steps: a step 210 of capturing the first calibration image 180 using the first image acquisition device 66 and the second calibration image 182 using the second image acquisition device 68, so that these each depict the calibration pattern 54; a step of creating the calibration representation 80 with the superimposed representation 82, which comprises the spatially adjacent sections 84 of the first calibration image 180 and the second calibration image 182 such that the image of the calibration pattern 54 is represented section by section in the spatially adjacent sections 84 of the first calibration image 180 and the second calibration image 182; and one step of checking the geometric calibration using the image of the calibration pattern 54 in the overlay representation 82.

[0121] According to one example, the verification process also includes the following steps: a step 213 of displaying the verification aid 94 in the calibration display 80, wherein the verification aid 94 frames the verification area 96 and thereby defines the tolerance range 98 for the verification; a step 214 of moving the verification aid 94 in the calibration representation 80 such that the first section 102 of the image of the calibration pattern 54 lies within the verification area 96, wherein the first section 102 originates from the first calibration image 180; and Step 215 involves checking whether the verification aid 94 is movable such that, in addition to the first section 102, the second section 104 of the image of the calibration pattern 54 lies within the verification area 96, wherein the second section 104 originates from the second calibration image 182. The verification procedure may include at least one further step 216.

[0122] The Fig. Figure 20 shows a schematic flowchart encompassing several steps of a preparation process. The preparation process includes the following steps: a step 220 of capturing the image of the optical target 20 with one of the image acquisition devices 66, 68, 88, 90; a step 221 of generating the representation of target 20 based on the captured image; one step of displaying the alignment aid 92 for the alignment of the optical target 20 relative to the image acquisition unit 64; and one step of aligning the optical target 20 with the alignment aid 92 by moving the target 20. The preparation process can include at least one further step 224. Reference symbol list 10 Test device 12 Light supply 14 Conversion element 16 first wavelength 18 second wavelength 20 optical target 22 Calibration image 24 bracket 26 medical imaging devices 28 spacers 30 distance 32 coupling section 34 lead 36 retaining element 38 reflective screen 40 cross-sectional area 42 Fiber optic connection 44 fiber optic cables 46 proximal end 48 first cross-sectional area 49 distal end 50 second cross-sectional area 52 Diffusion element 54 calibration patterns Line 56 58 Cross 59 central cross 60 Arm Quadrant 62 64 image capture units 66 first image capture device 68 second image capture device 70 first spectral range 72 second spectral range 74 Lighting device 78 Display device 80 Calibration display 82 Overlay representation Section 84 86 Input device 88 third image capture device 90 fourth image capture device 92 Alignment aid 94 Review Aid 96 Review area 98 Tolerance range 99 Review framework 100 System 101 Excerpt 102 first section 104 second section 106 image area 108 central area 110 central area of ​​a quadrant 112 Magnified view 113 Excerpt of the calibration representation 114 additional image capture devices 120 System 122 Support arm 124 equipment vehicles 126 Lighting supply connection 128 cases 130 entrance optics 132 first image sensor 134 second image sensor 136 Storage device 138 Handle 140 Rubber coating 142 recording slots 144 Closure plate 146 Exclusion 148 side wall 150 cavity 152 glass plates 154 slides 156 Stop section 158 Circumferential groove 160 abscissa 162 ordinates 164 wavelength range of visible light 166 Wavelength range of near-infrared light 168 first distribution 169 Chessboard 170 second distribution 172 Image of the calibration pattern 174 pixels 180 first calibration image 182 second calibration image 184 Offset Step 201 Step 202 Step 203 Step 204 Step 205 206 further step 210 steps Step 211 Step 212 Step 213 214 steps 215 steps 216 further step 220 steps 221 steps Step 222 Step 223 224 further step 225 Blending display

Claims

[1] Test apparatus (10), comprising: a light supply (12) which is designed to carry first illumination light; a conversion element (14) configured to convert light from the first illumination light with a first wavelength (16) at least partially into second illumination light with a second wavelength (18) different from the first wavelength (16); and an optical target (20) which is arranged such that first illumination light and second illumination light can be supplied to it for illuminating the target (20) in order to capture a calibration image (22) of the optical target (20). [2] Test device (10) according to claim 1, wherein the second wavelength (18) comprises a wavelength from the infrared range, in particular from the near-infrared range. [3] Test device (10) according to claim 1 or 2, wherein the first illumination light comprises at least predominantly light from the visible range. [4] Test device (10) according to one of the preceding claims, wherein the conversion element (14) is configured to convert light from the visible range at least partially into light from the infrared range. [5] Test apparatus (10) according to one of the preceding claims, wherein the conversion element (14) has luminescent properties, wherein the conversion element (14) is configured to convert light of the first illumination light with the first wavelength (16) at least partially into the second illumination light with the second wavelength (18) different from the first wavelength (16) by means of the luminescent properties. [6] Test device (10) according to one of the preceding claims, further comprising a holder (24), wherein the holder (24) is provided to make the test device (10) connectable to a medical imaging device (26) to be tested. [7] Test device (10) according to claim 6, wherein the holder (24) comprises a spacer (28) which defines a distance (30) between the medical imaging device (26) to be tested and the target (20). [8] Test device (10) according to claim 7, wherein the holder (24) is configured to support the weight of the test device (10) when coupled to the medical imaging device (26) under test. [9] Test device (10) according to claim 7 or 8, wherein the holder (24) comprises a coupling section (32) for coupling with the medical imaging device (26) to be tested, wherein the coupling section (32) includes a projection (34) which is designed to hold the test device (10) by gripping behind it. [10] Test device (10) according to claim 9, wherein the coupling section (32) further comprises a movable retaining element (36), which is designed to optionally fix the holder (24) to the medical imaging device (26) to be tested. [11] Test device (10) according to one of the preceding claims, wherein the light supply (12) comprises a reflective screen (38) which is configured to direct the illumination light to the conversion element (14), wherein the screen (38) has a cross-sectional area (40) that increases in the direction of the conversion element (14). [12] Test device (10) according to one of the preceding claims, further comprising a light guide connection (42) to which a light guide (44) can be connected in such a way that first illumination light guided in the light guide (44) can be coupled into the test device (10). [13] Test device (10) according to one of claims 11 or 12, wherein the optical fiber connection (42) is arranged at a proximal end (46) of the reflecting screen (38) which has a first cross-sectional area (48), and wherein the conversion element (14) is arranged at a distal end (49) of the reflecting screen (38) which has a second cross-sectional area (50), where the second cross-sectional area (50) is larger than the first cross-sectional area (48). [14] Test device (10) according to one of the preceding claims, wherein the light supply (12) comprises a diffusion element (52) which is configured to diffuse and homogenize light of the first illumination light. [15] Test device (10) according to one of the preceding claims, wherein the optical target (20) is movably mounted. [16] Test device (10) according to one of the preceding claims, wherein the optical target (20) comprises at least one calibration pattern (54), and wherein the calibration pattern (54) can be mapped onto the calibration image (22). [17] Testing device according to claim 16, wherein the calibration pattern (54) comprises at least one line (56) and / or a cross (58). [18] Testing device according to claim 16 or 17, wherein the calibration pattern comprises a central rectangular cross (59) with elongated arms (60), the center of which can be arranged in the center of the calibration image (22), and which divides the calibration image (22) into four quadrants (62), wherein in each of the four quadrants (62) there is another right-angled cross (58) with elongated arms (60), the center of which is located in a central area of ​​the corresponding quadrant (62). [19] Test device (10) according to one of the preceding claims, wherein the optical target (20) is integrated with the conversion element (14). [20] System (100), comprising: a test device (10) according to one of the preceding claims; and a medical imaging device (26) with an image acquisition unit (64), wherein the image acquisition unit (64) comprises: a first image acquisition device (66) which is light-sensitive in a first spectral range (70) comprising the first wavelength (16); and a second image acquisition device (68) which is light-sensitive in a second spectral range (72) different from the first spectral range (70) and which includes the second wavelength (18); wherein the image acquisition unit (64) has a geometric calibration of the first image acquisition device (66) and the second image acquisition device (68) with respect to their imaging areas; wherein the image acquisition unit (64) is configured to capture calibration images (22) of an optical target (20), and wherein the geometric calibration of the image acquisition unit (64) can be verified using the calibration images (22). [21] System (100) according to claim 20, further comprising a lighting device (74) which is connected and / or connectable to the light supply (12). [22] System (100) according to claim 21, wherein the illumination device (74) can be connected to the imaging device (26) in an imaging operating mode to provide illumination light during image acquisition. [23] System (100) according to one of claims 20 to 22, further comprising a display device (78) which is configured to display a calibration representation (80) based on the calibration images (22) to a user. [24] System (100) according to claim 23, wherein the calibration images (22) comprise at least one first calibration image (180) acquired by means of the first image acquisition device (66) and at least one second calibration image (182) acquired by means of the second image acquisition device (68); and wherein the calibration representation (80) comprises a superimposed representation (82) based on the first calibration image (180) and the second calibration image (182). [25] System (100) according to claim 24, wherein the superimposed representation (82) comprises spatially adjacent sections (84) of the first calibration image (180) and the second calibration image (182). [26] System (100) according to claim 24 or 25, wherein the superimposed representation (82) comprises sections (84) of the first calibration image (180) and the second calibration image (182) arranged alternately side by side in two different spatial directions. [27] System (100) according to any one of claims 24 to 26, wherein the optical target (20) comprises a calibration pattern (54), and wherein the sections (84) of the respective calibration images (22) used for the overlay representation (82) at least partially depict the calibration pattern (54). [28] System (100) according to one of claims 20 to 27, further comprising an input device (86) by means of which control commands for checking the calibration of the image acquisition unit (64) can be initiated by a user. [29] System (100) according to one of claims 23 to 28, wherein the display device (78) is configured to display an alignment aid (92) for the alignment of the optical target (20) relative to the image acquisition unit (64). [30] System (100) according to any one of claims 20 to 29, the image acquisition unit (64) further comprises: a third image acquisition device (88) which is light-sensitive in the first spectral range (70); and a fourth image acquisition device (90) that is light-sensitive in the second spectral range (72); and wherein stereo image acquisition in the first spectral range (70) is possible using the first image acquisition device (66) and the third image acquisition device (88), and wherein stereo image acquisition in the second spectral range (72) is possible using the second image acquisition device (68) and the fourth image acquisition device (90). [31] Testing method, in particular by means of a test device (10) according to any one of claims 1 to 19 and / or by means of a system (100) according to any one of claims 20 to 30, comprising: Generating first illumination light comprising light with a first wavelength (16); Generating a second illumination light comprising light with a second wavelength (18) different from the first wavelength (16); Supplying the first illumination light and the second illumination light to an optical target (20) for its illumination; Acquisition of calibration images (22) of the target (20) using a medical imaging device (26) with an image acquisition unit (64), wherein the image acquisition unit (64) comprises a first image acquisition device (66) that is photosensitive in a first spectral range (70) comprising the first wavelength (16), and a second image acquisition device (68) that is photosensitive in a second spectral range (72) different from the first spectral range (70) and comprising the second wavelength (18), wherein the image acquisition unit (64) has a geometric calibration of the first image acquisition device (66) and the second image acquisition device (68) with respect to their imaging ranges; and Checking the geometric calibration of the image acquisition unit (64) using the calibration images (22) of the optical target (20); wherein the generation of the second illumination light comprises a conversion of light of the first illumination light with the first wavelength (16) at least partially into second illumination light with the second wavelength (18) different from the first wavelength (16). [32] Test method according to claim 31, further comprising coupling the test device (10) to the medical imaging device (26). [33] Test method according to claim 31 or 32, further comprising connecting a lighting device (74) to the test device (10). [34] Test method according to claim 33, wherein the illumination device (74) is configured to be connected to the imaging device (26) in an imaging operating mode to provide illumination light during image acquisition. [35] System (120) for carrying out a test procedure according to one of claims 31 to 34. [36] Program code comprising instructions which, when executed by a processor, cause the execution of a test procedure according to any one of claims 31 to 34. [37] Computer program product comprising a machine-readable medium on which program code according to claim 36 is stored.

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