Method for optical calibration and identification

Abstract

Disclosed is a method for providing information by marking instruments for use in endoscopic interventions, said information making it possible to identify details about the instruments and carry out calibrations, such as spectral calibrations to achieve white balance or geometrical calibrations for measurements.

Description

Optical calibration and identification procedures Technical area

[0001] The present invention relates to a method for providing information by marking instruments, marking elements and tools provided with marking elements for use in such a method. background

[0002] Endoscopic surgical techniques have become established for a wide variety of surgical interventions. In this case, an endoscopic instrumentation, which can in particular comprise an endoscope and one or more endoscopic instruments, is guided through a natural body opening or an artificial one created with the help of an incision to an operating field located inside the body. Endoscopic instruments for this purpose have an elongated shaft, at the distal end (i.e. end furthest from the user) of which is arranged a tool for carrying out surgical manipulations. This tool can be operated by a handle arranged at the proximal end of the shaft (i.e. end closest to the user) or by a connection to motor drives via an elongated transmission element arranged in the shaft. The shaft can be rigid or flexible. The handle orDuring an endoscopic procedure, the connector remains outside the body opening, while the shaft with the tool is inserted through the body opening.

[0003] Endoscopic instruments differ, among other things, in the connected tool and thus in their function. There are also endoscopic instruments where the tool can be detached from the shaft and replaced with another. In particular, after an endoscopic procedure, the instrument can be disassembled for cleaning and / or sterilization.

[0004] Endoscopic instruments are typically used multiple times, and endoscopic surgical equipment typically includes multiple units of the respective endoscopic instruments. Methods are known in the state of the art, particularly using artificial intelligence, by means of which the instrument type can be recognized. However, these methods have not yet allowed not to perform detection and / or classification down to the level of the serial number and / or other detailed characteristics of the instrument.

[0005] Endoscopic procedures are typically performed with video support. This means that, in addition to the endoscopic instruments, an imaging device is also inserted into the body, capturing corresponding images of the surgical site and the instruments in use and displaying them on a suitable display device. Correct color reproduction is of paramount importance during imaging, particularly for the correct identification of tissue. The color representation in the image chain is influenced by various components, such as the light source used, the optics used, and / or the camera head. To obtain the best possible endoscopic image, it is advisable to perform a white balance before using the endoscopic system to ensure the various components used are aligned.For manual white balance, according to state-of-the-art methods, the user points the endoscope at a white or gray surface, and the white balance is performed, for example, by pressing a corresponding button in the control software. Subsequent changes, such as heating of the light source or changes in sensor efficiency due to temperature fluctuations, cannot be compensated for during the procedure according to state-of-the-art methods without removing the camera from the actual site of use. Removing an endoscope during surgery to perform calibration is possible in principle, but is complicated and time-consuming. Accordingly, recalibrations at the site of use are preferred.

[0006] In addition, geometric measurements are often performed during endoscopic procedures, for example, to measure structures such as tumors. Obtaining absolute measurements proves difficult, not least due to optical distortions that can vary depending on the optics used. Distortions, among other things, come into play here.

[0007] Depth determination using artificial intelligence algorithms is state of the art in the field of endoscopic measurements with a 2D endoscope, for example from “Digging Into Self-Supervised Monocular Depth Estimation”, Godard et.al., 04 Jun 2018-arXiv: Computer Vision and Pattern Recognition or "The Temporal Opportunist: Self-Supervised Multi-Frame Monocular Depth," Watson et al., IEEE Conference on Computer Vision and Pattern Recognition 2021. The resulting models can predict the depth of a tissue with pixel precision, but do not contain absolute depth information. Similar limitations arise from the application of other computer vision methods, such as "Structure From Motion," which can obtain 3D information by overlapping time-shifted images using parallax; here, too, absolute depth information cannot be obtained.

[0008] To compensate for distortions and thus for the calibration of geometric measuring systems, images of predefined geometric structures, such as a checkerboard pattern, are taken before the endoscopic system is used - similar to manual white balance - in order to determine the deviations and, if necessary, compensate for them in the display of the images. Summary of the invention

[0009] The object of the present invention is to at least partially overcome the disadvantages known in the prior art. This object is achieved by methods according to the invention according to claims 1 and 6, a marking area according to claim 9, and an instrument according to claim 15. Preferred embodiments of the invention are the subject of the corresponding subclaims.

[0010] The present invention discloses markings of instruments for use in endoscopic procedures by means of which, on the one hand, details of the respective instruments can be recognized, i.e., they can be identified, and, on the other hand, calibrations, such as spectral calibrations for white balance or geometric calibrations for measurements, can be carried out and assistance for endoscopic measurements can also be provided.

[0011] Accordingly, the present invention discloses a method for optical calibration of an imaging device, in particular an endoscope system, wherein the imaging device comprises an optical system with an optics and an image sensor for recording digital images. The method according to the invention comprises detecting a two-dimensional marking area in the field of view of the imaging device, wherein the The marking area comprises optoelectronically readable writings consisting of lines and / or dots of different widths and gaps therebetween, and the marking area has at least one calibration element with calibration information, detecting the calibration element, and calibrating the imaging device based on the calibration information.

[0012] An imaging device within the meaning of the present invention can be any technical and / or electronic device suitable for recording, further processing, and / or forwarding an image of a viewing area and, for example, displaying it on a screen. Medical imaging devices within the meaning of the present invention can be all types of endoscopes known to those skilled in the art, in particular dual endoscopes and stereo endoscopes. An endoscope is a generally narrow and elongated imaging device suitable for insertion into a cavity or through a generally small opening and for recording an image of a viewing area within the cavity and / or the area behind the small opening using at least one camera or at least one image sensor. Furthermore, spatial cameras can also be imaging devices within the meaning of the present invention.

[0013] Two-dimensional, within the meaning of the present invention, refers in particular to marking areas whose information content is based on a two-dimensional representation. This particularly applies to the application of corresponding two-dimensional marking areas on three-dimensional surfaces or surfaces with a three-dimensional structure, such as the surface of an instrument or the round shaft of an instrument.

[0014] Marking areas comprising optoelectronically readable writing within the meaning of the present invention are, in particular, barcodes, i.e., representations consisting of parallel lines and spaces of varying widths, and / or so-called QR codes, i.e., matrices consisting of black and white squares. Accordingly, data is represented in the form of binary symbols. This data can be mechanically read using optical reading devices, such as cameras, and further processed electronically. Further processing here includes both the extraction of the information represented directly and indirectly using the binary symbols, as well as the application of this information. Directly represented information is information encoded by binary symbols, indirectly represented information is information represented by the geometric shape (e.g. size) or the color design.

[0015] Calibration elements within the meaning of the present invention are any representation of information, in particular representations of specific, predefined color values ​​or predefined geometric patterns, based on which an optical calibration can be performed. Accordingly, calibration elements can have a specific color tone, such as pure white, or a predefined gray tone, via which spectral calibrations, such as white balance, are performed. If the material of the instrument has a known color tone, an untreated section can be provided as a calibration element. Calibration elements for geometric calibrations are, in particular, patterns or shapes with known dimensions. In particular, the entire marking area or parts of the marking area can also be provided as a calibration element.

[0016] White balance in the sense of the present invention is a tonal value correction by which color-neutral image reproduction, i.e. image reproduction without a color cast, can be achieved on a corresponding output device, such as a screen. Tonal value corrections can also be carried out separately for all existing color channels, usually the primary colors red, green and blue, whereby for white balance the corresponding tonal values ​​of the color channels must be calculated to the same brightness. For white balance, the brightest point in each color channel can be searched for in an image, and the corrections for the individual color channels can be calculated using these tonal values. White balance becomes problematic if there are no points in the input image to be used for white balance that correspond to the white point.Accordingly, gray or white reference surfaces can be used, although with white reference surfaces, care must be taken to ensure that the tonal values ​​are not saturated. According to the invention, the reference surfaces can be provided as calibration elements as part of a marking area arranged on an instrument.

[0017] In embodiments of the method according to the invention, the method may further comprise detecting at least two positioning elements, wherein the positioning elements may be part of the marking area can be integrated into the marking area or can be located in the immediate vicinity of the marking area.

[0018] Positioning elements within the meaning of the present invention are optically recognizable structures or information that facilitate the reading of information stored in the marking area and / or define specific areas. Thus, positioning elements can be used to define the calibration elements as such and, if necessary, to automatically recognize and read them, and / or to automatically start the corresponding calibration routine.

[0019] Accordingly, in embodiments of the method according to the invention, the positioning elements can identify the position of the at least one calibration element.

[0020] In embodiments of the method according to the invention, the at least one calibration element can be dimensioned such that it can be resolved by the image sensor. The limit value for structures resolvable by a sensor can be determined by the Nyquist limit and is accordingly dependent on the hardware used. In embodiments of the method according to the invention, the calibration information can include information on geometric and / or spectral calibration. In preferred embodiments of spectral calibration, the identification element is dimensioned such that at least one pixel of the sensor is completely filled when detected by the sensor. In preferred embodiments of geometric calibration, the identification element is dimensioned such that the structures can be resolved with high contrast.

[0021] In embodiments of the method according to the invention, the calibration element for spectral calibration can be at least partially monochrome and unstructured. The color to be used for calibration is not specified and can be selected depending on the application area, with white and shades of gray, similar to the gray cards in classical photography, being particularly preferred. A white balance as a specific form of spectral calibration can be adapted to specific applications such as the use of white light, hyperspectral imaging methods, and multispectral imaging methods. In hyperspectral imaging or multispectral imaging, the spatially and wavelength-resolved detection in different electromagnetic ranges (Spectrum) can be used to detect and visualize structures or objects that are invisible using conventional imaging techniques. In preferred embodiments, the calibration element can be unstructured and / or matte to prevent optical interference effects.

[0022] The present invention is further directed to a method for identifying instruments, in particular instruments for use in an endoscope system. The method according to the invention comprises detecting a two-dimensional identification area in the field of view of an imaging device, wherein the identification area comprises optoelectronically readable writing consisting of lines and / or dots of different widths and spaces therebetween, and the identification area encodes at least identification information.

[0023] In embodiments of the method for identifying instruments according to the invention, the imaging device can be a room camera or a camera directed at a specific area, such as a surgical trolley, or a specific object, such as a surgical tray.

[0024] Marking areas comprising optoelectronically readable writings within the meaning of the present invention are in particular barcodes, i.e. representations consisting of parallel lines and gaps of different widths and / or so-called QR codes, i.e. matrices consisting of black and white squares, which can represent information to the person skilled in the art in a standardized manner.

[0025] The present invention is further directed to identification areas for the optical calibration of an imaging device, in particular an endoscope system, and / or for the identification of instruments, in particular instruments for use in an endoscope system. The identification areas are optoelectronically readable inscriptions consisting of lines and / or dots of different widths and gaps therebetween, and contain at least one calibration element, wherein the calibration element comprises information for geometric and / or spectral calibration, and wherein the optoelectronically readable inscriptions encode identification information. Identification areas are, in particular, barcodes, i.e. representations consisting of parallel lines and gaps of different widths, and / or so-called QR codes, i.e. consisting of black and white squares. Matrices that can represent information to the expert in a standardized manner.

[0026] In embodiments of the two-dimensional marking areas according to the invention, at least two positioning elements can be arranged as part of the marking area, integrated into the marking area, or in the immediate vicinity of the marking area. The positioning elements can be arranged such that they unambiguously determine the position of the at least one calibration element and thus facilitate recognition and, in certain embodiments, also enable automatic recognition, particularly via computer-based object recognition.

[0027] In embodiments of the two-dimensional marking areas according to the invention, the at least one calibration element can be dimensioned such that it can be resolved by an image sensor as described above.

[0028] In embodiments of the two-dimensional marking areas according to the invention, the calibration information can include information for geometric and / or spectral calibration, as described above. Calibration elements for spectral calibration can be at least partially monochrome and unstructured.

[0029] The present invention is further directed to an instrument for use in a method for optical calibration described above and / or in a method for identification described above, comprising a two-dimensional marking area described above. In embodiments of the present invention, the two-dimensional marking area can be arranged on the instrument by means of printing technology, laser marking, etching, stamping, and / or labeling. In preferred embodiments, the basic color of the instrument material can be integrated as a component into the marking area. Short description of the figures

[0030] The accompanying drawings show exemplary embodiments of the invention and serve to explain the principles of the invention by way of example.

[0031] Fig. 1 shows a checkerboard pattern (1a) and representations of different distortions (1 b to 1e).

[0032] Figures 2a and 2b show the sequences of the methods according to the invention.

[0033] Figure 3 shows the application of the inventive methods

[0034] Figure 4 shows instruments with marking according to the invention.

[0035] Figure 5 shows a marking area with positioning elements and calibration elements.

[0036] Figure 6 shows a marking area with a calibration element.

[0037] Figure 7 shows a marking area (a) and schematically a perspective distortion on the instrument (b).

[0038] Figure 8 shows a marking area with geometric calibration element (a) and schematically a perspective distortion on the instrument (b). Detailed description

[0039] The present invention will now be described in more detail with reference to the accompanying drawings, which illustrate preferred embodiments. However, the teachings of the invention may be embodied in many different forms and are not to be construed as limited to the embodiments shown herein. It should be understood that these drawings are intended to illustrate the general features of the methods used in particular embodiments. However, the drawings may not precisely depict the structure or features of a particular embodiment. Moreover, like reference numerals in the drawings designate corresponding parts throughout the different views or embodiments.

[0040] Figure 1 shows the effects of distortion schematically. Distortion is a rotationally symmetric image error that increases from the center of the image to the edge of the image. This results in a local change in the Image scale within the image plane, which can be very disruptive in measurement applications. If the magnification increases towards the edges of the image field, a square is distorted in a pincushion shape. In the opposite case, this is referred to as barrel distortion. Figure 1a shows a checkerboard pattern without distortion. Figure 1b shows tangential distortion, Figure 1c a radial barrel distortion, Figure 1d a radial pincushion distortion and Figure 1e a tangential and radial distortion. Which image aberrations or combination of image aberrations occur depends on the optics used and also on the distance of the object or part of the object being displayed. By calibrating the system, distortions can be compensated for using digital image processing.While optically induced image errors can generally be compensated for effectively through a one-time calibration, for example, by comparing them with a calibration pattern during production, dynamic changes or perspective effects cannot be compensated for in advance. In particular, the possibilities for dynamic changes are so diverse that excluding them in advance, for example through design measures, is not possible. Aging processes, possibly promoted by external parameters such as the autoclaving of the imaging device or external forces acting during use, play a role in this. For example, the relative position of individual components of the optical system can change over time, which can have serious consequences for image reproduction.Likewise, forces occurring during movements of the imaging device can influence the optics or parts of the optics, such as the relative position of sensors or lenses. In addition, a change in the optics used, as in an endoscope with a proximal camera head, can also lead to changes; these optics changes cannot be detected by the camera without additional measures. Accordingly, dynamic, preferably automated calibrations according to the invention by performing the calibration routines during use are advantageous here.

[0041] Figure 2a shows the method for optical calibration of an imaging device, in particular an endoscope system, wherein the imaging device comprises an optical system with an optics and an image sensor for capturing digital images. At the beginning of the method, At least one digital image is recorded by the imaging device, whereby the recording of digital images can also take place continuously, for example in the form of video streams. When a corresponding identification area comes into the field of view of the imaging device, this is detected together with the calibration element contained therein. The detection can take place in particular with the aid of appropriate object recognition techniques. The subsequent calibration can then take place manually by the user using the information contained in the calibration element, semi-automatically, for example by automatic detection and / or selection of the respective calibration routines, but after initiation by suitable user inputs by the user, or fully automatically. Distortions can be compensated for using geometric calibration information, as described in Figure 1.Since the geometric calibration information is known, distortions caused by the optics used can be determined and compensated for by software for display on the output device. Likewise, spectral calibration information can be used for tonal value correction, particularly for white balance. For this purpose, a corresponding reference field with known properties, particularly a white or gray reference field, is captured and recognized; appropriate object recognition techniques can be applied.

[0042] Figure 2b shows the method for identifying instruments, in particular instruments for use in an endoscope system. At the beginning of the method, at least one digital image is captured using the imaging device; the digital images can also be captured continuously, for example, in the form of video streams. When a corresponding identification area comes into the field of view of the imaging device, this area and the identification information it contains are detected. Detection can be carried out, in particular, with the aid of appropriate object recognition techniques. Based on the identification information, for example, the use of the instrument can be logged, instrument-specific settings can be made, or instrument-specific information can be displayed to the user on a display device, such as a monitor.Alternatively or in addition, you can also. Subsequent, instrument-specific calibration routines can be initiated or suggested to the user. Room cameras can also be used as imaging devices for the identification process, as described below in connection with Figure 4. In addition to documenting the use of the identified instrument, identification also allows for verification, e.g., via certificates of authenticity, or comparing suitability with regard to the intended use, and the like. Thus, a system user can be given further information about the instrument identification via a corresponding display device. Accordingly, warnings can be displayed if unverified and / or incompatible devices are detected.

[0043] In preferred embodiments, the methods for calibration and identification are applied in combination, i.e., the marking areas contain both calibration elements and identification information.

[0044] Figure 3 is a schematic representation of the application of the methods described in Figures 2a and 2b in the context of an endoscopic operation in an operating room. The operating room is equipped with typical endoscopic surgical equipment, including an endoscope with camera 2 and instruments, with one instrument 3 inserted into the endoscope and the remaining instruments lying in a tray 4. The operating room also has a room camera 1, a control unit 6, and a monitor 5. The room camera 1 can be used to identify the instruments located in the tray 4, as well as the instrument(s) 3 in use, using the method according to the invention. In addition, the instruments in use can be identified via the endoscope camera according to the method according to the invention, or corresponding calibration routines can be carried out.As described above, the calibration routines can be performed manually, semi-automatically, or fully automatically. The digital image of the instrument with the marking area can also be displayed on monitor 5. Continuous, automatic calibration is also possible. In addition, image changes can be detected, for example, based on digital image analysis, particularly with the aid of artificial intelligence, and subsequent calibrations can be suggested or performed. Depending on the calibration, the display on the monitor was corrected with tonal values ​​and / or distortion compensation. By regularly capturing the marking areas, any newly occurring deviations, for example, caused by temperature changes, can be dynamically recorded and, if necessary, recalibrations can be performed or suggested via monitor 5 as a corresponding notification to the system user.

[0045] As described above, by applying marking areas to an endoscopic instrument 3, it is possible to read this marking area via the endoscopic image captured by the endoscope camera 2. This makes it possible, among other things, to uniquely identify and log the instrument type using the serial number encoded in the marking area. By correlating it with events (such as the occurrence of bleeding) that have occurred with a specific instrument, further analyses can be performed that can lead to an improvement in the indication. By capturing the marking area(s) via the room camera 1, digital sieve screening is enabled, thus enabling optimization processes.

[0046] Figure 4a shows a marking area in the form of a circumferential barcode on an endoscopic instrument. Figure 4b shows the marking of an endoscopic instrument using so-called QR codes. In both cases, distances between individual elements of the marking area or the overall size (length, width, or a combination of length and width) can be used as geometric calibration information prior to measurements. As described in connection with Figure 1, calibration steps may be necessary to compensate for image errors. However, since the dimensions of the marking areas are known, they can be used for the respective calibrations, or the need for calibration can even be automatically detected and performed if necessary based on analysis of the digital images.

[0047] Figure 5 shows a marking area 50 in the form of a further developed barcode. In addition to the familiar parallel lines of varying thickness, the marking area 50 has calibration elements 54 and positioning elements 52. A calibration element can be defined by triangulation, represented by the auxiliary lines 56. This allows Calibration elements 54 can be verified. For example, this can ensure that only calibration elements 54 that are properly aligned with the imaging device (e.g., when three positioning elements 52 are visible) are used for calibrations. The dimensions of the marking area 50 and / or the thickness and spacing of individual lines can thus be used as scale or geometric calibration information.

[0048] Figure 6 shows a marking area 60 in the form of a further developed QR code. A calibration element 64 is arranged centrally as a gray section for spectral calibration, similar to white balance. The typical corner elements of the QR code serve as positioning elements 62. The dimensions of the marking area 60 and / or the size of individual squares can thus be used as a scale or geometric calibration information. The geometric arrangement of the calibration element 64 in the marking area 60 is fundamentally free; however, in preferred embodiments, this arrangement is uniform; the calibration element 64 is arranged at corresponding positions within different marking areas, which can facilitate automated detection.

[0049] Figure 7a shows another embodiment of a marking area 70 in the form of a further developed QR code. Here, the calibration element 74 for spectral calibration is arranged as a white field for white balance in one of the corner elements typical of the QR code. The other two corner elements 72 serve as positioning elements. As already described above, the geometric arrangement of the calibration element 74 in the marking area 70 is also free here, but in preferred embodiments, it is uniform.

[0050] Figure 7b shows the marking area 70 of Figure 7a, arranged on a section 78 of an endoscopic instrument, illustrating the perspective distortion. By knowing the dimensions of the marking area 70, the endoscopic system can be calibrated to enable absolute measurements. For this purpose, a white balance can be performed via the calibration element 74—even during use without removing the endoscope from the work area.

[0051] Figure 8a shows another embodiment of a marking area 80 in the form of a further developed barcode. Here, the barcode is extended by a geometric calibration element 84.

[0052] Figure 8b shows the marking area 80 of Figure 8a, arranged on a section 80 of an endoscopic instrument, illustrating the perspective distortion. The calibration element 84 can be used directly as a scale or for geometric calibrations.

[0053] The scope of this disclosure includes all changes, substitutions, variations, alterations, and modifications to the embodiments described or illustrated herein that would be understood by one of ordinary skill in the art. The scope of this disclosure is not limited to the embodiments described or illustrated herein. Moreover, although this disclosure describes and illustrates particular embodiments herein as including particular components, elements, features, functions, operations, or steps, any of these embodiments may include any combinations or permutations of any components, elements, features, functions, operations, or steps described or illustrated elsewhere herein that would be understood by one of ordinary skill in the art.A reference in the appended claims to a method or apparatus, or a component of an apparatus, or a system being adapted, arranged, capable, configured, enabled, operable, or ready to perform a particular function further includes that apparatus, system, or component, regardless of whether it or that particular function is enabled, turned on, or enabled, as long as that apparatus, system, or component is adapted, arranged, capable, configured, enabled, operable, or ready to perform it. Furthermore, although this disclosure describes or illustrates certain embodiments as providing certain advantages, certain embodiments may provide none, some, or all of these advantages.

Claims

Claims 1. A method for optically calibrating an imaging device, in particular an endoscope system, wherein the imaging device has an optical system with an optics and an image sensor for recording digital images, comprising: Capturing a two-dimensional marking area in the field of view of the imaging device, wherein the marking area comprises optoelectronically readable writings consisting of lines and / or dots of different widths and gaps therebetween, and the marking area has at least one calibration element with calibration information; Detecting the calibration element; and Calibrate the imaging device based on the calibration information.

2. The method according to claim 1, further comprising detecting at least two positioning elements, wherein the positioning elements are part of the marking area, are integrated in the marking area or are located in the immediate vicinity of the marking area.

3. The method according to claim 2, wherein the positioning elements indicate the position of the at least one calibration element.

4. Method according to one of the preceding claims, wherein the at least one calibration element is dimensioned such that it can be resolved by the image sensor.

5. Method according to one of the preceding claims, wherein the calibration information comprises information on geometric and / or spectral calibration.

6. The method according to claim 5, wherein the calibration element for spectral calibration is at least partially monochrome and unstructured.

7. Method according to one of the preceding claims, wherein the calibration is carried out automatically upon detection of the at least one calibration element.

7. A method for identifying instruments, in particular instruments for use in an endoscope system, comprising: Capturing a two-dimensional marking area in the field of view of an imaging device, wherein the marking area comprises optoelectronically readable writings consisting of lines and / or dots of different widths and gaps therebetween, and the marking area encodes at least identification information.

8. The method of claim 7, wherein the imaging device is a space camera.

9. A two-dimensional marking area for optically calibrating an imaging device, in particular an endoscope system, and / or for identifying instruments, in particular instruments for use in an endoscope system, comprising: optoelectronically readable inscriptions consisting of lines and / or dots of different widths and gaps therebetween; at least one calibration element, wherein the calibration element comprises information for geometric and / or spectral calibration, wherein the optoelectronically readable inscriptions encode identification information.

10. Two-dimensional marking area according to claim 9, wherein at least two positioning elements as part of the marking area, in integrated into the marking area or arranged in the immediate vicinity of the marking area.

11. A two-dimensional marking area according to claim 10, wherein the positioning elements indicate the position of the at least one calibration element.

12. Two-dimensional marking area according to one of claims 9 to 11, wherein the at least one calibration element is dimensioned such that it can be resolved by an image sensor.

13. Two-dimensional marking area according to one of claims 9 to 12, wherein the calibration information comprises information on geometric and / or spectral calibration.

14. A two-dimensional marking area according to claim 13, wherein the calibration element for spectral calibration is at least partially monochrome and unstructured.

15. An instrument for use in a method of optical calibration according to any one of claims 1 to 6 or in a method of identification according to any one of claims 7 or 8, comprising a two-dimensional identification area according to any one of claims 9 to 143.

16. Instrument according to claim 15, wherein the two-dimensional marking area is arranged by means of printing technology, laser marking, etching engraving, punching and / or labeling.

Images