Method and device for determining a spatial pose of a non-spherical object

Abstract

The invention relates to a method and to a device for determining a spatial pose of a non-spherical object (110) which comprises at least one surface portion (111) having a known shape. The method comprises the following steps: a) radiating at least two light fields (100) through a lens (70) onto the object (110), wherein: each light field (100) has known phase fronts (104); the phase fronts (104) of the at least two light fields (100) differ from one another at least downstream of the lens (70); a curvature of the phase fronts (104) at an exit window of the lens (70) is smaller in at least one spatial direction than the smallest curvature of the surface portion (111) of the object (110); for at least one of the light fields (100), there is at least one line lying in the surface portion (111), along which at least two local surface normals (112) of the surface portion (111) are orthogonal to the phase front (104) of the at least one of the light fields (100); b) detecting a reflected portion (102), originating from the object (110), of the at least two light fields (100) by means of a detector (80); and c) determining the spatial pose of the non-spherical object (110) on the basis of the detected reflected portion (102) of the at least two light fields (100) by taking into consideration an expected backscatter signal resulting from the known shape of the surface portion (111). The method and the device preferably enable determination of the spatial pose of a cylindrical object, in particular of a glass fiber.

Description

[0001] Method and device for determining a spatial position of a non-spherical object

[0002] Field of the invention

[0003] The present invention relates to a method and a device for determining the spatial position of a non-spherical object, as well as a corresponding computer program. In many applications, the object is a cylindrical object, in particular a fiber optic cable; however, the use of another object is possible.

[0004] State of the art

[0005] The present invention is located in the field of photonics, in particular in the field of assembly and connection technology for optical components. The challenge in this field is to effectively couple light from the outside into an optical component or to couple it out from an optical component to the outside. Glass fibers, i.e. optical waveguides comprising a glass fiber core and a glass fiber cladding, are a basic building block here. They are designed to guide light effectively by exploiting an optical refractive index difference between the glass fiber core and the glass fiber cladding. In order to guide the light to or away from an optical component, however, it is necessary to ensure that the light is coupled in or out of the glass fiber. The coupling of a glass fiber to an optical component, in particular a laser or a photonic integrated circuit (PIC).photonic integrated circuit (PIC) or a photodetector, can be done in different ways; preferably.

[0006] - via a direct mechanical coupling of the fiber optic cable (butt-coupling)

[0007] - via an optical free beam path using optical elements, in particular optical lenses or mirrors: or

[0008] - using 3D printed freeform waveguides (photonic wire bonds).

[0009] Each of these coupling mechanisms presents different challenges.

[0010] With direct mechanical coupling, it is necessary to position the optical fiber precisely and to match a mode field on one side of the optical component to the mode field of the optical fiber. If the mode field of the optical component is not matched to the mode field of the optical fiber, optical lenses and collimator optics must be attached for the free-space path, which also require highly precise alignment. The state of the art for positioning the optical fiber for light coupling is active coupling (active alignment). This involves a mechanical gripper spatially moving the optical fiber while simultaneously coupling light with a laser to one end of the optical fiber, and monitoring the output signal with a photodiode. The higher the power in the photodiode, the better the coupling. Once the coupling is satisfactory, the gripper is stabilized and the optical fiber is glued.This approach has several disadvantages: on the one hand, it is very time-consuming, on the other hand, it is subject to constant wear and tear on the equipment. Furthermore, it involves the mechanically problematic bonding of the glass fibers, and finally, the optical path of the optical component must be accessible in order to measure a coupled signal on the photodiode. Another option for directly coupling a glass fiber to a chip without active coupling is the use of V-shaped grooves on the chip. In this way, the glass fiber is aligned to the waveguide on the chip by mechanically restricting the grooves during insertion. However, this approach requires greater effort on the chip side. The mode field adaptation must take place on the chip, and the grooves take up valuable chip area.Furthermore, this form of coupling requires very tight tolerances in the production of the trenches and the diameter of the fiber optic cable, which are often not available in practice.

[0011] In general, it is advantageous, particularly with regard to effort and speed of the procedure, not to actively couple the fiber optic cable to the optical component, i.e. without measuring light through the fiber optic cable on a detector in order to optimize for a signal. Passive coupling requires that the positions of the coupling points of a light entry and exit from the fiber optic cable and the optical component, e.g. the PIC, are measured very precisely and that an optical connection is established between the fiber optic cable and the optical component on the basis of this measured information. Determining the position and orientation of a fiber optic core in space is often made difficult by the fact that the facet of the fiber optic cable is inaccessible and / or the fiber optic cable is embedded in a fiber optic array.

[0012] When using freeform waveguides as an alternative to active coupling, an optical connection between two optical components is created using direct-writing 3D lithography. This also requires the precise determination of the position and orientation of the optical components. This approach presents an additional challenge in that the optical fiber must be detected while it is installed in a two-photon lithography system. Therefore, there are only limited options for viewing the optical fiber from different sides using a conventional imaging technique. Typically, a two-photon lithography system only offers the option of viewing the optical components and / or the optical fiber from above using a camera or scanning them using a laser beam.

[0013] Particularly when using direct-writing two-photon lithography, it is often necessary to determine the exact position and orientation of one or more objects, especially in order to write at least one optical element onto an object with precise alignment. One application can be selected, in particular, from the detection of the position and orientation of waveguides, coupling points, or surfaces of optical components, preferably glass fibers, optical chips, or lasers. According to the prior art, imaging methods are used for this purpose, preferably a camera that can capture images through a lens of a lithography system and, using a suitable procedure, in particular by taking images of the optical component in different sectional planes (focus stacking), can determine information about the position and orientation.In principle, an optical element such as a fiber optic core can be detected using a microscope or using optics in a direct-writing lithography system due to the difference in refractive index between the fiber optic core and the fiber optic cladding. However, undefined background illumination, which can occur particularly in non-transparent structures, can lead to a low signal-to-noise ratio and thus to poor reproducibility. Furthermore, with complex arrangements of fiber optics, e.g., in a V-groove, the signal behavior cannot be clearly determined, so detection using conventional imaging in a microscope is only feasible to a very limited extent.

[0014] To determine the exact position and orientation of a fiber optic cable, for example in a splicing device, special lighting is often used according to the prior art. US 4,492,463 A discloses that for this purpose the fiber optic cable is illuminated from one side, and the deflection of the light by the fiber optic cable on the opposite side is recorded in transmitted light, with the fiber optic cable or the associated fiber optic core acting as an optical lens. However, this method can only be used if the fiber optic cable is optically accessible from two opposite sides. This is not usually the case, especially with fully assembled optical components, since here the fiber optic cable is typically attached to a metal or silicon substrate. A further hurdle is presented by fiber optic arrays that have been glued into a glass block for easier handling.The glass block can distort the light path and thus prevent the fiber optic cable from being detected in transmitted light. A lithography system for creating photonic connections often uses a positioning table or platform on which the optical components intended for the connection are placed. Cameras mounted on opposite sides would severely limit the size of the optical components. Furthermore, arranging the cameras in a mechanically movable manner within the integrated structure is a significant effort, which would lead to increased wear and tear on the lithography system.

[0015] US 4,506,947 A or US 4,690,493 A disclose that the optical fiber is irradiated with ultraviolet light, causing the associated fiber core to fluoresce, and the resulting fluorescent light is analyzed. However, this process can only be used if the optical component can be exposed to ultraviolet radiation. This is not possible when using 3D lithography with a UV-sensitive photoresist, because the latter cures under UV irradiation. A further limitation of this process is the mandatory difference in fluorescence between the fiber core and the fiber cladding.

[0016] Methods that use confocal microscopy to detect objects are also known. DB Hovis & AH Heuer, The use of laser scanning confocal microscopy (LSCM) in materials science, Journal of Microscopy 140, pp. 173-180, 2010 describe a classic confocal microscope that has a focus point that can be moved using galvanometric scanners. In classic confocal microscopy or laser scanning confocal microscopy, either the surface reflection of an object or the fluorescence of the object to be detected or the surrounding area is used to generate image data by scanning the surface using the focus point. A classic confocal microscope can also be used in a direct-writing lithography system; in this case, an exposure laser can be used for a confocal measurement, whereby a laser intensity below the polymerization threshold is typically selected.This enables the detection of the surface of optical components, e.g. waveguides, or of associated coupling points, e.g. in optical chips or lasers. Objects such as optical components or substrates with and without topography can be detected using a confocal scan, provided they have a certain reflectivity. However, a simple confocal scan using a beam focused onto the surface of a fiber optic cable has the problem that the lateral position of the fiber optic axis cannot be determined accurately enough, since the detected backscatter signal drops off very quickly if the focus is moved away from the fiber optic cable perpendicular to the direction of the fiber optic cable. Furthermore, detection inaccuracies arise if only a segment of the fiber optic surface is scanned and the radius of the object is determined using a fit.Furthermore, the rotation axis cannot be detected with high accuracy for cylindrical objects made of transparent material.

[0017] If an optical component, e.g. a glass fiber, is embedded in a medium that exhibits two-photon fluorescence when irradiated with light, the position and orientation of the glass fiber could be detected by scanning a (partial) volume around the glass fiber with a laser, in particular with the exposure laser of a lithography system, at low power. A transition between the presence and absence of fluorescence defines an interface of the glass fiber, across which the extent of the glass fiber can be determined. If this data is known, the radius and position of the glass fiber can be determined. However, this method is inherently slow because a large volume has to be scanned. Furthermore, inaccuracies in the detection arise if only a segment of the glass fiber is scanned and the radius is determined using a fit.To achieve this, the radius of the fiber optic cable must be as uniform as possible, otherwise further inaccuracies will occur. Furthermore, the presence of a fluorescent material outside the fiber optic cable is required.

[0018] W. Weise, P. Zinin, T. Wilson, A. Briggs, and S. Boseck, "Imaging of spheres with the confocal scanning optical microscope," Opt. Lett. 21, pp. 1800-1802 (1996), describe a theoretical, three-dimensional distribution of a backscattered signal that results from imaging a reflecting sphere with a confocal microscope and compare this with corresponding measurements. However, this publication does not describe a method for determining the spatial position of an object, particularly the sphere. Furthermore, it does not consider the backreflection of non-spherical objects, which is required for the detection of a cylindrical optical fiber.

[0019] Y. Xiao, L. Qiu, and W. Zhao, "Laser confocal cylindrical radius measurement method and its system," Applied Optics 56(23), 2017, describe a confocal characterization of hollow cylinders. For this purpose, a cylindrical phase front is irradiated onto a cylindrical test object, exploiting the property that a portion of a cylindrical surface acts as a retroreflector when the illuminating light field is focused on the center of the cylinder. In this configuration, however, the position is known exactly a priori, and the measurement is used exclusively to determine the radius of the cylinder. Furthermore, only hollow cylinders are used as test objects.

[0020] P. Chiariotti, M. Fitti, P. Castellini, S. Zitti, M. Zannini and N. Paone, High-accuracy dimensional measurement of cylindrical components by an automated test station based on confocal chromatic sensor, Proceedings of IEEE International Workshop on Metrology for Industry 4.0 & IoT, 2018, describe the use of chromatic confocal detectors to characterize the radii of hollow cylinders. In the described method, the orientation of the axis of the hollow cylinder relative to the measuring system is determined in order to automatically position the detector in the center of the hollow cylinder. For this purpose, a chromatic confocal sensor is placed inside a hollow cylinder and rotated. The chromatic confocal sensor determines the distance to the cylinder in one direction, which determines the rotation of the sensor within the cylinder and the spatial position of the axis of the hollow cylinder.However, the method requires a light source to rotate within the object, making it suitable only for hollow cylinders. Furthermore, implementing a light source to determine the spatial position of optical fibers within an optical arrangement rotating around the fiber axis is extremely difficult.

[0021] JH Burge, "Fizeau interferometry for large convex surfaces," SPIE Vol. 2536, pp. 127-138, 1995, describes the design of a special Fizeau interferometer. This interferometer uses a spherical reference surface to determine the surface quality of a test object using an interferometric setup. Determining the spatial position of an object is not described here, nor is it readily possible with this setup.

[0022] Object of the invention

[0023] Based on this, the object of the present invention is to provide a method and a device for determining a spatial position of a non-spherical object as well as an associated computer program, which at least partially overcome the disadvantages and limitations of the prior art.

[0024] In particular, the present invention is intended to enable the most accurate possible determination of the spatial position of an object, in particular a glass fiber, especially when the object, in particular the glass fiber, is located on a substrate and / or within a two-photon lithography system and is difficult to access. The determination of the spatial position of the object should also be possible if the object is at least partially surrounded by a photoresist. Furthermore, the determination of the spatial position of the object should also be possible if the accessible detection volume is very small. Furthermore, the optics for detecting the position of the object should largely coincide with the optics for exposing the object, in particular to reduce potential errors and offsets between the production of the object and its detection. Disclosure of the Invention

[0025] This object is achieved by a method and a device for determining the spatial position of a non-spherical object, as well as by an associated computer program having the features of the independent patent claims. Advantageous further developments, which can be implemented individually or in any combination, are presented in the following description and the dependent claims.

[0026] In a first aspect, the present invention relates to a method for determining a spatial position of a non-spherical object having at least one surface section of known shape. The term "object" here refers to an extended object, animate or inanimate, having a surface accessible by the present method. The term "non-spherical object" refers to an object whose surface deviates from a spherical shape. The non-spherical object can preferably be a cylindrical object, in particular an optical fiber. The term "optical fiber" here refers to a cylindrical object comprising a glass fiber core and a glass fiber cladding, which is configured as an optical waveguide to effectively guide light by exploiting an optical refractive index difference between the glass fiber core and the glass fiber cladding.

[0027] The term “spatial position” refers to information relating to the location of an extended object in space, particularly in the form of values ​​with reference to a coordinate system. The coordinate system can preferably be selected from a Cartesian coordinate system, a cylindrical coordinate system, or a polar coordinate system; however, the use of another coordinate system is conceivable. In general, the spatial position of the object can be composed of a position of the object and an orientation of the object. Here, the term “position” refers to a location in space at which a point, particularly a center point or center of gravity, of the object is located, while the term “orientation” indicates a direction in which an axis of the object, particularly a longitudinal axis of a cylindrical object, preferably a fiber optic cable, is aligned.

[0028] The present method for determining a spatial position of a non-spherical object having at least one surface section of known shape comprises the following steps: a) irradiating at least two light fields through an objective onto the object, each light field having known phase fronts, the phase fronts of the at least two light fields differing from one another at least downstream of the objective, a curvature of the phase fronts at an exit window of the objective being less in at least one spatial direction than a smallest curvature of the surface section of the object, for at least one of the light fields there being at least one line lying in the surface section along which at least two local surface normals of the surface section are orthogonal to the phase front of at least one of the light fields;b) detecting a reflected portion of the at least two light fields emanating from the object by means of a detector; and c) determining the spatial position of the non-spherical object from the detected reflected portion of the at least two light fields, taking into account an expected backscatter signal resulting from the known shape of the surface section.

[0029] The steps of the present method can preferably be carried out in the specified order, beginning with step a), following with step b), and ending with step c), wherein one or more, in particular consecutive steps, can also be carried out at least partially simultaneously. In a preferred embodiment, steps a) and b) of the present method can be repeated with a plurality of different light fields generated one after the other, each having different phase fronts. The term "one after the other" refers to a temporal sequence according to which the respective light fields are generated one after the other and irradiated onto the object.The time interval between two consecutive light fields is preferably 0.1 ps to 100 ms, particularly preferably 1 ps to 100 ps; however, the use of a different time interval is possible. In an alternative embodiment, the at least two light fields can be irradiated simultaneously in step a) if the detector used in step b) is configured to detect the reflected portion of the at least two light fields emanating from the object in a spatially resolved manner. Regardless of the selected embodiment, the spatial position of the object can preferably be determined within 30 seconds, particularly preferably within 10 seconds.

[0030] According to the invention, the spatial position of a non-spherical object is determined by scanning a surface section of the object with at least two light fields, which have different phase fronts at least downstream of the objective, as per step a). Upstream of the objective, the at least two light fields can still be identical, while downstream of the objective, according to the invention, they differ from one another. The term “downstream of the objective” refers to a direction in the propagation direction of the at least two light fields. As described in more detail below, in a particular embodiment, a difference between the phase fronts downstream of the objective can be generated by moving the objective in the z-direction, wherein the position of the at least one galvanometric scanner in the xy plane remains the same. However, other embodiments for generating the required difference between the phase fronts downstream of the objective are conceivable.

[0031] The term "light field" here refers to a spatially extended light beam, which is preferably present as a collimated light beam, wherein the term "spatially extended" indicates that the light beam has a diameter, preferably from 0.1 mm to 100 mm, more preferably from 1 mm to 20 mm. "Scanning" of the surface section of the object takes place in that the at least two light fields are each focused using an objective lens, so that the mutually different phase fronts, which are preferably essentially spherical, impinge on the surface section of the object. The surface section of the object can preferably be scanned using 2 to 2,000,000, preferably 50,000 to 750,000, light fields with mutually different phase fronts; however, the use of a different number of light fields is possible.

[0032] The term “surface section” refers to a part of the surface of the extended object whose geometric shape, referred to as “shape,” is known. The shape of the surface section can be characterized by means of local surface normals, where the term “surface normal” refers to an imaginary vector orthogonal to the outer surface of the surface section. The term “orthogonal” refers to an angle of 90° ± 1°, preferably 90° ± 0.1°. In a particular embodiment, the surface section of known shape can comprise the entire surface of the object. Alternatively or additionally, a distribution of a reflected portion of the at least two light fields over the entire surface of the object can be known, modeled, or estimated. The term “spherical” refers to phase fronts that represent a section of a spherical surface.The term “essentially” here includes a deviation of the total area of ​​the phase front of at most 10%, preferably of at most 1%, from a section of a spherical surface.

[0033] The term "surface section of known shape" refers to the presence of basic information about the spatial shape of the surface section. This does not require the shape to be known in detail or with all parameters. In an embodiment in which the surface section has a cylindrical shape, it is not necessary for the inventive method for determining the spatial position of the non-spherical object to know the diameter of the object; information that a cylindrical shape is present is sufficient.Alternatively or additionally, the basic information about the spatial shape of the surface section can also be determined indirectly, preferably by means of a detection according to the invention and an additional ex-situ measurement using a further method, preferably in order to determine a relative position between a detected maximum in the light field and the surface section.

[0034] The term “phase front” refers to an imaginary surface on which all points have the same phase, with the phase front moving at the speed of light in the direction of the surface normal of the phase front. The phase fronts, which differ from one another at least downstream of the objective lens and which impinge on the surface section of the object simultaneously or preferably one after the other, can preferably be generated by moving a focal point of the light field in all three spatial directions using a device designed for this purpose. At least one of the light fields can be changed accordingly, preferably in a beam path in front of an objective lens. At least one galvanometric scanner can preferably be used for this purpose. Alternatively or additionally, a relative displacement between the objective lens and the object can occur between the irradiation of the at least two light fields.For this purpose, at least one element can be used that is configured to displace the object and / or the objective, preferably selected from a positioning stage, which can preferably be operated piezoelectrically, or by means of an inductive element, in particular a voice coil. The term "different phase fronts" refers to a difference in the phase fronts relative to the object, in particular to a surface section of the object.

[0035] Further alternatively or additionally, the change in at least one of the light fields can be carried out by means of a diffractive element. The diffractive element can in particular comprise a digital light modulation element which has a multiplicity of individually controllable optical elements which are designed to modulate an incoming light beam. The digital light modulation element can preferably comprise a spatial light modulator or a digital micromirror unit. The term “spatial light modulator” (SLM) refers to an optical device which is designed to impress an intensity pattern, in particular in the form of a spatial modulation of an amplitude and / or a phase, onto an incoming light beam, wherein the intensity pattern can be impressed electronically and / or optically.A digital micromirror device (DMD) is an arrangement comprising a plurality of tiltable micromirrors arranged in a matrix, each of which has an edge length in the micrometer range, whereby each micromirror can be individually adjusted using electrostatic fields.

[0036] By changing the position of the focal point relative to the object, the preferably substantially spherical phase fronts can impinge on the surface section of the object from different directions and with different curvatures. If, furthermore, according to step a), the curvature of the phase front in at least one spatial direction coincides with the curvature of the surface section in the same spatial direction, or if at least one line exists in the surface section along which at least two local surface normals of the surface section are orthogonal to the phase front of the light field currently impinging on the surface section, a significant portion of the light field incident on the object is reflected back onto itself as a reflected portion of the at least two light fields.The term "reflected" refers to a process in which a portion of the light field strikes a surface, whereby the phase fronts of the light field change in such a way that they overlap with the light field striking the surface. The term "curvature" refers to a local deviation of a surface's contour from a plane in at least one dimension. Furthermore, the term "line" refers to an imaginary contour of a spatial arrangement; in this case, the imaginary contour of the spatial arrangement of the at least two local surface normals, which are orthogonal to the phase front of the light field currently impinging on the surface section, on the surface section under consideration.

[0037] In order for the respective light field to be reflected by the object, a refractive index difference can exist between the object and the medium surrounding the object. In this case, a refractive index difference of < 0.2, preferably < 0.1, can be sufficient for a detectable backscattered signal. In particular, when the object is transparent or partially transparent, the reflected portion of the at least two light fields emanating from the object can be generated at the surface section of known shape and at an inner interface in an interior space of the object. In this case, two local surface normals of the surface section exist at an inner interface in the interior space, which are orthogonal to the phase front of the light field currently impinging on the surface section.In a particular embodiment, a combination of the reflection of the at least two light fields at the surface as well as at the inner interface can be used for detection. Alternatively, the object can be non-transparent, preferably by being coated at least in the area of ​​the surface section. In this embodiment, the reflected portion of the at least two light fields emanating from the object can be generated exclusively at the surface section of known shape. If the illumination field is completely reflected before it propagates through the focus area, no real focus area exists. In this case, a virtual focus area can be regarded as the focus area of ​​the imaginary, non-reflected beam. However, the determination of the spatial position of the object, in particular an axis of symmetry of a cylindrical object, is also possible if only a virtual focus area exists.Coating at least the surface portion of the object can preferably be achieved by metallization or by deposition of a dielectric layer stack (Bragg mirror); however, an alternative or additional use of another process is possible. This embodiment can be particularly advantageous in that a higher signal contrast can be achieved by the opaque coating of at least the surface portion of the object.

[0038] In a particularly preferred embodiment, according to which the spatial position of a cylindrical object, in particular a glass fiber, is determined, the curvature of the essentially spherical phase fronts only corresponds to the curvature of the object in one spatial direction when the focal region lies in the center of the cylinder. The term "focal region" refers to a volume around the focal point within which the incident intensity exceeds a predetermined intensity threshold. The intensity threshold can be a value of at least 36.8% (i.e., ~ 1 / e) or at least 50% of the maximum intensity occurring at the focal point; however, the use of a different value is possible.

[0039] In a particularly preferred embodiment, the at least two local surface normals of the surface section can be orthogonal to the phase front of the light field currently acting on the surface section, wherein the distance between the focal point and the surface section preferably corresponds to at least twice the diameter of the focal area, particularly preferably at least five times the diameter of the focal area.

[0040] According to step b), the reflected portion of the at least two light fields emanating from the object is detected by a detector, preferably a confocal detector. For this purpose, the reflected portion of the at least two light fields is detected for at least two light fields with different phase fronts. For this purpose, the reflected portion of the at least two light fields can be coupled out of a common beam path with the portion of the light field incident on the object by means of a beam splitter in order to generate the light field incident on the detector; however, the use of at least one other optical element or another type of beam path suitable for this purpose is possible.

[0041] In a particularly preferred embodiment, the detector can comprise a focusing optic configured to focus the light field incident on the detector onto an aperture before it impinges on a photodetector. In an alternative embodiment, the confocal detector can have a fiber optic cable instead of the aperture, which is configured to guide the light field incident on the fiber optic cable to the photodetector.

[0042] In a further embodiment, the detector can detect the backscatter signal from multiple positions with spatial resolution. This embodiment is particularly advantageous when the at least two light fields in step a) are irradiated simultaneously.

[0043] However, further designs of the detector are conceivable.

[0044] In a particular embodiment, the detection of the reflected portion of the at least two light fields emanating from the object can be carried out by the detector synchronously with the generation of the temporally successive light fields. As soon as a newly formed light field, which has a different phase front from the previous light field, is irradiated onto the object, the detection of the reflected portion of the at least two light fields emanating from the object can be carried out again. The term "synchronous" thus refers to a temporal coordination between steps a) and b), and preferably additionally step c), iebetween generating and irradiating a selected light field onto the object according to step a) and detecting a reflected portion of the selected light field emanating from the object by means of the detector according to step b) and, preferably, determining the spatial position of the object from the detected reflected portion of the selected light field according to step c). However, other embodiments are possible.

[0045] If the shape of the surface section and the incident phase fronts are known, the spatial position, i.e. the position and orientation, of the object is determined according to step c). By repeatedly carrying out steps a) and b), information about the intensity of the portion reflected by the object for each of the incident light fields with different phase fronts can be obtained. The intensity of the light field detected in the detector is highest when there is at least one line lying in the surface section along which at least two local surface normals of the surface section are orthogonal to the phase front of at least one of the light fields. From the signals detected by the detector, together with the associated incident light fields and phase fronts, the signals with the highest intensity can be determined.The corresponding phase fronts then represent individual surface sections, which together enable the detection of the position and orientation of the object.

[0046] In a preferred embodiment, the focused portion of the light field can first be deflected laterally, i.e., perpendicular to the propagation direction of the light field, in two dimensions, and the reflected signal can be recorded for each point on this area spanned by the two dimensions. The focal point is preferably located within a cylindrical object, particularly preferably near the rotation axis of the cylindrical object. The spatial sampling rate can preferably be 10 nm to 10 pm, particularly preferably 50 nm to 500 nm. The intensity of the reflected signal detected in the detector can preferably be stored together with the associated position of the focal point.The focal point can then be shifted in the direction of propagation of the light field, preferably by 10 nm to 10 pm, particularly preferably by 50 nm to 500 nm, so that a further area can be scanned perpendicular to the direction of propagation and the intensity values ​​can be stored together with the associated positions of the focal point. By further repetition of this procedure, a volume can be scanned layer by layer through the focal point. From the stored data of the scanned volume, those focal points or groups of focal points for which the intensity is highest can now be determined. The expression that "the intensity is highest" here refers to an intensity above a specified intensity threshold. The position of these focal points essentially corresponds to the desired spatial position of the central axis of the cylindrical object.The term “substantially” here encompasses a deviation of the position of the central axis of the cylindrical object of better than 1 pm, particularly preferably better than 500 nm, and a deviation of the orientation of preferably better than 1°, particularly preferably better than 0.5°, with respect to the actual spatial position of the central axis of the cylindrical object, which can be determined in particular in tests to calibrate the present method using other methods and devices. To determine the highest intensity, methods from industrial image processing can preferably be used. In this case, edge detection can be carried out for each scanned area in order to determine a light-dark contrast between the focal points or the groups of focal points and their surroundings on the respective area.Preferably, an axis of symmetry of the cylindrical object can be determined in the area or in a partial area of ​​the area which has the highest light-dark contrast.

[0047] In a particularly preferred embodiment, the present invention enables the position and orientation of a glass fiber to be determined by scanning a volume in the glass fiber body perpendicular to the rotation axis using a focused light field, wherein a confocal detector is preferably used for detection. The glass fiber can be part of a structure that comprises other optical components in addition to the glass fiber. The structure can be configured such that a photonic wire bond or a microlens can be introduced as an optical connection between the glass fiber and another optical component using a direct-writing lithography process. Part of the glass fiber and / or part of the structure can be embedded in a photoresist for this purpose.By appropriately arranging the light source, lens, object, and detector, only those rays that intersect the center of the fiber optic cable and are thus guided through the fiber optic core can be detected by the detector. In other words: when scanning a partial volume, the backscattered signal detected by the detector can achieve a maximum amplitude when the focus area is in the center of the fiber optic cable, i.e., in the fiber optic core. In this embodiment, the interior of the fiber optic cable is scanned rather than the surface, resulting in greater detection accuracy. After detection, the photonic wire bond or micro-optics can be manufactured in situ using the same light source and lens.

[0048] In a further aspect, the present invention relates to a computer program for determining the spatial position of a non-spherical object. In a preferred embodiment, the computer program is stored on a non-transient, computer-readable medium. The terms "non-transient, computer-readable medium" or "computer-readable data carrier" refer to a non-volatile data storage medium, e.g., a hardware storage medium on which computer-executable instructions are stored, in particular a random access memory (RAM) or a read-only memory (ROM).The non-transient, computer-readable medium may preferably contain instructions which, when executed by the computer or a computer network, cause the computer or the computer network to control and / or execute at least step c), preferably all steps, of determining the spatial position of the non-spherical object according to the method described herein for determining a spatial position of a non-spherical object.

[0049] In a further aspect, the present invention relates to a device for determining a spatial position of a non-spherical object having at least one surface section of known shape. The device comprises:

[0050] - at least one light source configured to generate at least two light fields, each light field having known phase fronts, the phase fronts of the at least two light fields differing from one another at least downstream of the objective, a curvature of the phase fronts at an exit window of the objective being less in at least one spatial direction than a smallest curvature of the surface section of the object, at least one line lying in the surface section along which at least two local surface normals of the surface section are orthogonal to the phase front of at least one of the light fields;

[0051] - at least one lens designed to irradiate at least two light fields onto the object;

[0052] - at least one detector configured to detect a reflected portion of the at least two light fields emanating from the object; and

[0053] - at least one evaluation and control device which is designed to determine the spatial position of the non-spherical object from the detected reflected portion of the at least two light fields, taking into account an expected backscatter signal which results from the known shape of the surface section.

[0054] The term “evaluation and control device” refers to a device that is configured to receive, process, and output data. This can preferably be an electronically or optoelectronically controllable device, which in particular can have a computer, microcomputer, or programmable chip, e.g. an application-specific integrated circuit (ASIC) or an FPGA (field-programmable gate array), wherein the evaluation and control device can access one or more computer programs that can be configured to carry out the method described herein. Alternatively or additionally, the evaluation and control device can be comprised of a mobile communications device, in particular a smartphone, tablet, or laptop.However, other configurations of the evaluation and control device are possible, for example, integration of the evaluation and control device into a server. However, this does not require the evaluation and control device to be located in the same room or environment as the other components of the device; using a computer network, the evaluation and control device can also be located in a different room, building, city, state, or continent.

[0055] For further details regarding the present device and the computer program, reference is made to the description of the method according to the invention.

[0056] Advantages of the invention

[0057] The present invention solves the problem of determining the most accurate value possible for the position and orientation of an object in space, in particular of a glass fiber, which is preferably introduced into a lithography system. The position and orientation of the object in space can be determined using an optical method, wherein the shape of at least one surface section of the object is known. In particular, the present invention can be used to reliably detect axes of rotation of cylindrical, transparent or non-transparent objects. The object to be detected can be fixed to a carrier that is not transparent and / or whose accessibility from different spatial directions is restricted. Thus, the object may generally not be accessible from all sides, but rather irradiated with a light field essentially only from one spatial direction, and whose backreflection can be observed.Advantageously, the position and orientation of the object in space can be determined independently of any background lighting or scattered light from the environment.

[0058] The present invention also enables the detection of an object that is at least partially surrounded by a photoresist. Furthermore, the object can also be detected with a very small accessible detection volume, preferably 300 pm x 300 pm x 300 pm or smaller, in particular 80 pm x 80 pm x 80 pm or smaller; for glass fibers, a detection volume of 200 pm x 200 pm x 200 pm or smaller, in particular 40 pm x 40 pm x 40 pm or smaller, may be sufficient for reliable detection. The present invention further enables the construction and use of a two-photon lithography system such that the optics for detecting the position of the object largely coincide with the optics for exposure to produce an object.In particular, a laser, often pulsed in the fs range, the galvanometric scanner, and the lens of a lithography system can be used to generate at least two light fields. This type of setup minimizes potential errors and offsets between the fabrication of the object and its detection.

[0059] The detection of the spatial position of the object with the present invention can be carried out robustly, regardless of the type of optical structure and the object's environment. In particular, the position of the object can be detected with an accuracy of preferably better than 1 pm, particularly preferably better than 500 nm, and the orientation with a deviation of preferably better than 1°, particularly preferably better than 0.5°. In this way, a particularly low-loss coupling to a fiber optic cable whose spatial position was determined with the present invention can be achieved. Although the image field for detecting the fiber optic cable is limited by the optics of the lithography system when the fiber optic cable is used in a high-resolution lithography system, the present invention makes it possible to detect the fiber optic cable with the same optical system that is also used for lithography.

[0060] Particularly in the case of optical assemblies in which an object is mounted on a subrack, the present invention can be used to perform optical detection despite insufficient lighting, even if the object is difficult to access because it is either installed on a sample or because access cannot be guaranteed due to a process machine. The present invention is particularly suitable for industrial use, as it enables rapid measurement, achieves short cycle times and can therefore save effort and costs without compromising the accuracy of the measurement. The method is also suitable for detecting general objects and is therefore not dependent on the presence of fluorescence in the object or the object's surroundings for detection.

[0061] Furthermore, it is not necessary to separately measure the object's surface or to determine it using an approximation method, in particular a fit, to detect an object. Especially for a cylindrical object, the backscatter signal in the method according to the invention is maximized when the focal point lies on the object's axis to be detected. In this way, high detection precision can be achieved.

[0062] Herein, the terms "have," "have," "comprise," or "include," or any grammatical variations thereof, are used non-exclusively. Accordingly, these terms can refer both to situations in which, besides the features introduced by these terms, no further features are present, or to situations in which one or more further features are present. For example, the expression "A has B," "A has B," "A comprises B," or "A includes B" can refer both to the situation in which, apart from B, no further element is present in A (i.e., a situation in which A consists exclusively of B), and to the situation in which, in addition to B, one or more further elements are present in A, for example, element C, elements C and D, or even further elements.

[0063] Furthermore, it should be noted that the terms "at least one" and "one or more," as well as grammatical variations of these terms, when used in connection with one or more elements or features and intended to express that the element or feature may be provided singly or multiple times, are generally used only once, for example, when the feature or element is first introduced. When the feature or element is subsequently mentioned again, the corresponding term "at least one" or "one or more" is generally no longer used, without limiting the possibility that the feature or element may be provided singly or multiple times.

[0064] Furthermore, the terms "preferred", "preferably", "in particular", "for example" or similar terms are used herein in connection with optional features, without limiting alternative embodiments. Thus, features introduced by these terms are optional features, and these features are not intended to limit the scope of the claims and in particular the independent claims. Thus, as those skilled in the art will recognize, the invention can also be carried out using other embodiments. Similarly, features introduced by "in an embodiment of the invention" or by "in an embodiment of the invention" are understood to be optional features, without limiting alternative embodiments or the scope of the independent claims.Furthermore, these introductory expressions are intended to leave untouched all possibilities of combining the features introduced thereby with other features, whether optional or non-optional.

[0065] Short description of the characters

[0066] Further details and features of the present invention will become apparent from the following description of a preferred embodiment, particularly in conjunction with the dependent claims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the embodiments. The embodiments are schematically illustrated in the following figures. Like reference numerals in the figures denote like or functionally identical elements, or elements that correspond to one another in terms of their functions. In detail:

[0067] Figure 1 is a schematic representation of an embodiment of a device for determining a spatial position of a non-spherical object; and

[0068] Figure 2 is a schematic representation of an embodiment of a method for determining a spatial position of a non-spherical object.

[0069] Description of the embodiments

[0070] Figure 1 shows a schematic representation of an exemplary embodiment of a device 10 for determining a spatial position of a non-spherical object 110, which comprises at least one surface section 111 of known shape, wherein the shape of the surface section 111 can be characterized by means of local surface normals 112. The non-spherical object 110 shown here as an example is a cylindrical object, which can in particular be designed as a glass fiber, wherein any part of the cladding of the cylindrical object, in particular of the glass fiber, can be used as the surface section 111 of known shape. In a particularly preferred embodiment, the position of a glass fiber can be detected within a lithography system. Here, the position and orientation of the glass fiber core of the glass fiber are to be detected in three dimensions.The optical fiber can preferably be part of an optical structure, which can limit accessibility from all spatial directions. In particular, a front facet of the optical fiber can be inaccessible to imaging optical systems. However, the examination of an object 110 of a different shape is possible as long as its shape is known in at least one surface section 111.

[0071] The exemplary device 10, schematically illustrated in Figure 1, comprises a light source 50, a beam splitter 60, an optional galvanometric scanner 75, an objective lens 70, and a detector 80. The light source 50 is configured to generate a light field 100, which is guided to the objective lens 70 in a beam path illustrated in Figure 1A. For this purpose, the light field 100 is guided in the z-direction according to the coordinate system 120, also illustrated in Figure 1A. The light source 50 can preferably be embodied as a laser or comprise a laser, in particular a femtosecond laser (fs laser). In a particularly preferred embodiment, the light source 50 can simultaneously be configured as an exposure laser of a lithography system. This enables detection and writing at exactly the same position; calibration errors or imaging errors can be automatically compensated.The wavelength of the light source is preferably 300 nm to 3000 nm, particularly preferably 500 nm to 1500 nm. However, the use of a different type of light source 50 is possible. The lens 70 is configured to generate a focused portion 101 from the light field 100 generated by the light source 50, which is focused on a focus point 103 surrounded by a focus region. In the illustration according to Figure 1A, the focus point 103 is a real focus point located within the object 110. Furthermore, the galvanometric scanner 75 is configured to influence the light field 100 generated by the light source 50 in the beam path in front of the lens 70 such that the focus region around the focus point 103 generated by the lens 70 is adjusted in the lateral direction. According to the schematically illustrated coordinate system 120, this is the x-direction and / or the y-direction.The galvanometric scanner 75 can in particular be configured to deflect the light field 110 at a variable angle, wherein the angle can be predetermined by an evaluation and control device 150.

[0072] Alternatively or in addition to the galvanometric scanner 75, the light field 100 generated by the light source 50 can be influenced by moving the lens 70, in particular by means of a positioning stage, which is preferably operated piezoelectrically, or by means of an inductive element, in particular a voice coil. This alternative is illustrated schematically in Figures 1B and 1C. Other possibilities for influencing the light field 100 generated by the light source 50 are conceivable, preferably by means of a diffractive element (not shown). The diffractive element can in particular comprise a digital light modulation element as explained in more detail above, in particular a spatial light modulator or a digital micromirror unit.

[0073] In a preferred embodiment, the object 110 is transparent or at least partially transparent to the incident light field 110, so that the focused portion 101 of the light field 100 generated by the lens 70 can enter an interior space 113 of the object 110 in a region of the surface section 111 of known shape. In particular, due to a refractive index difference between a substance located in the interior space 113 of the object 110 and a material surrounding the object 110, a portion of the focused portion 101 of the light field 100 generated by the lens 70 is reflected at an inner boundary surface 114 of the object 110, thus generating a reflected portion 102 of the light field 100.The material that at least partially surrounds the object 110 can, in particular, be selected from air, an adhesive that can also be configured to secure the object, an immersion medium for an objective lens with a high numerical aperture NA, in particular a numerical aperture NA>1, or a photoresist that can also be configured as an immersion medium. In an alternative embodiment (not shown), the object 110 can comprise a substance that is opaque to the incident light field 100, or at least one of the surface portions 111 of the object 110 can be provided with a coating that is opaque to the incident light field 100, so that the reflected portion 102 of the light field 100 is generated by reflection of the focused portion 101 of the light field 100 generated by the objective lens 70 at the relevant surface portion 111 of the object 110.In this embodiment, the beam paths shown in Figure 1 within the object 110, including the focal point 103, are to be considered virtual. If the light field 100 is completely reflected before propagating through the focal region, no real focal region exists; in this embodiment, a virtual focal region can be considered the focal region of the imaginary, non-reflected light field. This embodiment can be particularly advantageous in that the opaque coating of at least the surface section 111 of the object 110 can enable an increase in signal contrast. The coating of at least the surface section 111 of the object 110 can preferably be carried out by means of metallization; however, an alternative or additional use of another process is possible.

[0074] As Figure 1 further shows, the portion 101 of the light field 100 generated by the light source 50 and focused by the lens 70 has known phase fronts 104, which are schematically represented as dashed lines. In the illustrated embodiment, the phase fronts 104 are essentially spherical, wherein a curvature of the essentially spherical phase fronts 104 at an exit window of the lens 70 in at least one spatial direction, in Figure 1 in particular in the direction along the z-axis, is less than a smallest curvature of the surface section 111 of the object 110. This makes it possible to set a working distance between the lens 70 and the surface section 111 of the object 110 that is suitable for carrying out the present method, in particular for the essentially spherical phase fronts 104.

[0075] As further shown in Figure 1, the beam splitter 60 is configured to guide the reflected portion 102 of the light field 100 toward the detector 80, which thereby forms a light field 105 incident on the detector 80. In particular, to achieve the highest possible spatial resolution, the detector 80 can be designed as a confocal detector. For this purpose, the detector 80 can have a focusing optics (not shown) that focuses the light field 105 incident on the detector 80 onto an aperture before it strikes a photodetector. In an alternative embodiment, the confocal detector can have a glass fiber (not shown) instead of the aperture, which is configured to guide the light field 105 incident on the glass fiber onto the photodetector.The use of the lens 70 as a common optical element, shown by way of example in Figure 1, which is configured both for illuminating the object 110 and for detecting the reflected portion 102 of the light field 100, is advantageous, in particular since in this way any imaging errors in the lens 70 are automatically corrected and thus an additional calibration of a second lens can be omitted.

[0076] According to the invention, the surface section 111 of the object 110 is illuminated sequentially with at least two, preferably a plurality, of different light fields 100, each having a known phase front 104, wherein the phase fronts 104 of the at least two, preferably the plurality, of light fields 100 differ from one another at least after the lens 70. In this way, in particular, a "scanning" of the surface section 111 of the object 110 can take place. According to the invention, the scanning of the surface section 111 of the object 110 is carried out until, for at least one of the light fields 100, at least one line (not shown) lying in the surface section 111 exists, along which the at least two local surface normals 112 of the surface section 111 are orthogonal to the phase front 104 of the at least one light field 110.

[0077] Signals are generated in the detector 80 that are based on the light field 105 impinging on the detector 80 and that can be detected and recorded by an evaluation and control device 150. The detection and recording of the signals from the detector 80 can preferably take place synchronously with the movement of the focal point 103. Using an algorithm configured for this purpose, the desired position and orientation of the object 110 can be determined from the signals. As schematically shown in Figure 1, the evaluation and control device 150 can be embodied as a personal computer (PC) that can be controlled by a monitor 152 and / or a keyboard 154. Alternatively or additionally (not shown), the evaluation and control device 150 can be embodied as an electronic communications device, preferably a smartphone, tablet, or laptop, which includes the monitor 152 and the keyboard 154.The monitor 152 can have a screen 153 on which the object 110 and / or its determined spatial position can be displayed. The evaluation and control device 150 can further have connections 151 by means of which it can be connected, in particular, to the light source 50, the galvanometric scanner 75, the detector 80, the monitor 152, and / or the keyboard 154, wherein the connection 151 can be wired or wireless. As mentioned above, however, it is not necessary for the evaluation and control device 150 to be located in the same room or in the same environment as the other components of the device 10; using a computer network, the evaluation and control device 150 can also be arranged in a different room, a different building, a different city, a different state, or a different continent. Other designs of the evaluation and control device 150 are possible.

[0078] As shown in Figure 1A, a portion 101 of the light field 102 focused on the real or virtual focal point 103 is imaged onto itself when the focal area intersects an axis of symmetry of the object 110. If the focal area lies at the center 115 of the cylindrical object, in particular the fiber optic cable, the inner boundary surface 114 of the cylindrical object 110 acts as a retroreflector, generating the reflected portion 102 of the light field 100, which—due to the backreflection—spatially overlaps with the portion 101 of the light field 100 focused on the focal point 103. By means of the beam splitter 60, the reflected portion 102 of the light field 100 can impinge on the detector 80 as the light field 105 and be registered there with a signal intensity.

[0079] However, if the focus area is located, as in the illustrations according to Figures 1B and 1C, actually or virtually outside the center 115 of the cylindrical object 110, the portion 102 of the light field 100 reflected at the inner boundary surface 114 of the cylindrical object 110 is not imaged onto itself and is therefore defocused when it strikes the detector 80, resulting in a low signal intensity compared to the situation shown in Figure 1A.

[0080] To determine the position and orientation of object 110 in space, at least two, preferably a plurality of points are identified in a region of surface section 111 at which the surface of object 110 functions as the best possible retroreflector. To obtain the plurality of points in surface section 111, the position of focal point 103 can preferably be changed relative to the center point 115 of object 110. For this purpose, as described above, the movable lens 70 and / or the galvanometric scanner 75 can be used, wherein the galvanometric scanner 75 is configured to deflect light field 110 at a variable angle, wherein the angle to be set in each case can be predetermined by the evaluation and control device 150.By determining a plurality of maxima in the light field 105 impinging on the detector 80, an axis of a cylindrical object 110 can be determined; for this purpose, a further dimension, in particular a radius, of the cylindrical object 110 does not need to be known.

[0081] Figure 2 shows a schematic representation of an embodiment of a method for determining a spatial position of a non-spherical object 110 in space. The lens 70 generates the focused portion of the light field 101 from the light field 100. According to steps a) and b), the focal point 103 is first deflected laterally by the galvanometric scanner 75 within a surface 201 of the xy plane in the coordinate system 120, and the light field 105 incident on the detector 80 is recorded for each point in this surface 201 by the detector 80. The focal point 103 is preferably located within the object 110, preferably the cylindrical object, in particular the optical fiber. Scanning the surface with the focal point 103 is not necessary. The spatial sampling rate, ie a distance between the points 210 representing the respective focus point 103 in the area, is preferably 10 nm to 10 pm, particularly preferably 50 nm to 500 nm.The detected intensity of the reflected signal is stored together with the corresponding position of the focal point 103 in the control and evaluation unit 150. The focal point 103 is then shifted in the propagation direction of the light field 100, i.e. along the z-direction, preferably by 10 nm to 5 pm, particularly preferably by 50 nm to 500 nm. The shift in the z-direction can be effected by shifting the objective 70. Subsequently, a further area 202, 203, 204 is scanned in the xy-plane, and the intensity values ​​detected by the detector 80 are stored together with the corresponding positions of the points 210 representing the respective focal point 103. By further repetitions of this process, a volume through the focal point 103 is scanned layer by layer.From the data of the scanned volume stored in the control and evaluation unit 150, those focal points 103 or groups of focal points 103 for which the intensity is highest can now be determined. The position of these focal points 103 essentially coincides with the position of the central axis of the cylindrical object 110. To determine the maximum intensity, at least one intensity threshold can be defined, whereby those intensities that exceed the intensity threshold with the highest value can be considered the highest intensities.

[0082] To determine the highest intensity, methods from industrial image processing can preferably be used. For example, edge detection can be performed for each scanned area 201, 202, 203, 204, in particular to determine a light-dark contrast between the points 210 representing the respective focal points 103 and their surroundings on the associated area 201, 202, 203, 204. From the area 201, 202, 203, 204 exhibiting the highest edge contrast, the position of an axis of symmetry of the cylindrical object 110 can thus be determined. For a more precise determination of the position of the axis of symmetry, each detected area 201, 202, 203, 204 can preferably be divided into sub-areas perpendicular to the presumed axis of symmetry, and the light-dark contrast can be recorded for each sub-area. The position of the axis of symmetry can then be determined by evaluating the sub-areas with the highest contrast across all surfaces 201, 202, 203, 204.For example, points 210 on a left-hand portion of surface 203 may exhibit the highest intensity. From this determination, the position and orientation of the axis of symmetry in object 110 can be determined, and if the symmetry is known, particularly in the case of a cylindrical object, the position of the entire object 110 can be deduced. Many other examples are conceivable.

[0083] Layer-by-layer scanning of the volume inside object 110 in lateral slices is only one possible embodiment. Other approaches, such as scanning in vertical planes or even spirals, are also conceivable. Furthermore, it is also possible to configure the scanning adaptively, for example, by adjusting the sampling rate depending on the signal at detector 115.

[0084] List of reference symbols

[0085] 10 Device for determining a spatial position of a non-spherical object

[0086] 50 light source

[0087] 60 beam splitters

[0088] 70 lens

[0089] 75 galvanometric scanner

[0090] 80 detector

[0091] 100 light field

[0092] 101 focused portion of the light field

[0093] 102 reflected part of the light field

[0094] 103 Focus point

[0095] 104 Phase front

[0096] 105 light field incident on the detector

[0097] 110 objects

[0098] 111 Surface section

[0099] 112 local surface normals

[0100] 113 Interior

[0101] 114 inner interface

[0102] 115 Center

[0103] 120 coordinate system

[0104] 150 Evaluation and control device

[0105] 151 connection

[0106] 152 monitors

[0107] 153 screen

[0108] 154 keyboard

[0109] 201, 202, 203, 204 Area

[0110] 210 points in the area representing the respective focus point

Claims

Patent claims 1. A method for determining a spatial position of a non-spherical object (110) having at least one surface section (111) of known shape, comprising the following steps: a) irradiating at least two light fields (100) through an objective lens (70) onto the object (110), each light field (100) having known phase fronts (104), the phase fronts (104) of the at least two light fields (100) differing from one another at least after the objective lens (70), a curvature of the phase fronts (104) at an exit window of the objective lens (70) being less in at least one spatial direction than a smallest curvature of the surface section (111) of the object (110), at least one line lying in the surface section (111) existing for at least one of the light fields (100),along which at least two local surface normals (112) of the surface section (111) are orthogonal to the phase front (104) of at least one of the light fields (100); b) detecting a reflected portion (102) of the at least two light fields (100) emanating from the object (110) by means of a detector (80); and c) determining the spatial position of the non-spherical object (110) from the detected reflected portion (102) of the at least two light fields (100), taking into account an expected backscatter signal resulting from the known shape of the surface section (111).

2. Method according to the preceding claim, wherein the irradiation of the at least two light fields (100) through the lens (70) onto the object (110) takes place in temporal succession.

3. Method according to one of the preceding claims, wherein the at least two light fields (100) are or comprise focused beams of rays, wherein the focused beams of rays have substantially spherical phase fronts (104).

4. Method according to one of the preceding claims, wherein the at least two local surface normals (112) of the surface section (111) are orthogonal to the phase front (104) of the light field (100) currently impinging on the surface section (111), wherein a distance between the focal point (103) and the surface section (111) corresponds to at least twice the diameter of a focal area.

5. Method according to one of the preceding claims, wherein the phase fronts (104) of the at least two light fields (100) differ from each other in that - at least one of the light fields (100) in a beam path in front of the objective (70) is changed by means of a galvanometric scanner (75); or - a change in at least one of the light fields (100) is carried out by means of a diffractive element; or - a relative displacement between the lens (70) and the object (110) occurs between the irradiation of the at least two light fields (100).

6. Method according to one of the preceding claims, wherein the reflected portion (102) of the at least two light fields (100) emanating from the object (110) is generated at the surface portion (111) of known shape and / or at an inner boundary surface (114) in an interior space (113) of the object (110).

7. Method according to one of the preceding claims, wherein the surface section (111) of known shape comprises an entire surface of the object (110), or wherein a distribution of the reflected portion (102) of the at least two light fields (100) on the entire surface of the object (110) is known, modeled or estimated.

8. Method according to one of the preceding claims, wherein the detection of the reflected portion (102) of the at least two light fields emanating from the object (110) (100) by means of a detector (80) synchronously with the generation of the temporally successive light fields (100).

9. Method according to one of the preceding claims, wherein a focused portion (101) of the light field (100) is deflected in two dimensions perpendicular to the propagation direction of the light field (100), and the reflected portion (102) of the light field (100) emanating from the object (110) is detected on at least two surfaces (201, 202, 203, 204) spanned in the two dimensions, wherein between a detection of the reflected portion (102) of the light field (100) emanating from the object (110) on two different surfaces (201, 202, 203, 204), a relative change in the position of a focal point (103) of the light field (100) with respect to the object (110) takes place, wherein the determination of the spatial position of the object (110) takes place from those focal points (103) or groups of focal points (103) which have an intensity of the light emitted by the object (110) outgoing reflected portion (102) of the light field (100) above at least one intensity threshold and are at a distance from the surface of the object (110),which is at least twice the diameter of the focus area.

10. Method according to the preceding claim, wherein a method for edge detection on the at least two surfaces (201, 202, 203, 204) is used to determine the intensity of the reflected portion (102) emanating from the object (110), wherein the method for edge detection is designed to determine a light-dark contrast between the focus points (103) or the groups of focus points (103) and their respective surroundings on the relevant surface (201, 202, 203, 204).

11. A computer program for determining a spatial position of a non-spherical object (110) having a surface section (111) of known shape, wherein the computer program comprises instructions which, when the computer program is executed by a computer or a computer network, cause the computer or the computer network to carry out at least step c) of the method for determining a spatial position of a non-spherical object (110) having at least one surface section (111) of known shape, according to one of the preceding method claims.

12. Device for determining a spatial position of a non-spherical object (110) having a surface portion (111) of known shape, comprising: - at least one light source (50) configured to generate at least two light fields (100), each light field (100) having known phase fronts (104), the phase fronts (104) of the at least two light fields (100) differing from one another at least downstream of the objective lens (70), a curvature of the phase fronts (104) at an exit window of the objective lens (70) being less in at least one spatial direction than a smallest curvature of the surface section (111) of the object (110), for at least one of the light fields (100) there being at least one line lying in the surface section (111), along which line at least two local surface normals (112) of the surface section (111) are orthogonal to the phase front (104) of at least one of the light fields (100); - at least one lens (70) which is arranged to irradiate the at least two light fields (100) onto the object (110); - at least one detector (80) which is arranged to detect a reflected portion (102) of the at least two light fields (100) emanating from the object (110); and - at least one evaluation and control device (150) which is used to determine the spatial position of the non-spherical object (110) from the detected reflected portion (102) of the at least two light fields (100) taking into account an expected backscatter signal resulting from the known shape of the surface section (111).

13. Device according to the preceding claim, wherein the light source (50) is a laser of a direct writing lithography system.

14. Device according to one of the preceding device claims, the at least one lens (70) is further configured to irradiate at least one light field (105) onto the detector (80).

15. Device according to one of the preceding device claims, further comprising at least one galvanometric scanner (75) which is configured to change at least one of the light fields (100) in a beam path in front of the objective (70).

16. Device according to one of the preceding device claims, further comprising at least one element which is configured to displace the object (110) and / or the objective (70), preferably selected from a positioning table or an inductive element.

17. Device according to one of the preceding device claims, further comprising at least one diffractive element which is configured to effect a change in at least one of the light fields (100), wherein the diffractive element is preferably a digital light modulation element, in particular selected from a spatial light modulator or a digital micromirror unit.

Images