Method and device for determining spatial position of non-spherical object

Abstract

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

Description

TECHNICAL FIELD

[0001] The invention relates to a method and apparatus for determining the spatial position of a non-spherical object and an associated computer program. In many applications, the object is a cylindrical object, in particular a glass fiber; however, other objects can also be used. BACKGROUND

[0002] The invention belongs to the field of photonics, in particular the field of assembly and packaging of optical components. A challenge in this field is to efficiently couple light into or out of an optical component. Glass fibers, i.e. optical fibers comprising a glass fiber core and a glass fiber cladding, are the basic building blocks for this purpose. They are configured to efficiently guide light through them by exploiting the optical refractive index difference between the glass fiber core and the glass fiber cladding. However, in order to guide light to or from an optical component, it is necessary to ensure that light is coupled into or out of the glass fiber. The coupling of a glass fiber to an optical component, in particular a laser, a photonic integrated circuit (PIC) or a photodetector, can be done in different ways; preferably, - via a direct mechanical coupling onto the glass fiber (butt coupling); - via an optical free-beam segment by using optical elements, in particular optical lenses or mirrors; or - by using a 3D-printed free-form waveguide (photonic wire bonding).

[0003] For each of these coupling mechanisms, there are different challenges.

[0004] For direct mechanical coupling, the glass fiber needs to be precisely positioned and the mode field on one side of the optical component needs to be matched to the mode field of the glass fiber. If the mode field of the optical component does not match the mode field of the glass fiber, an optical lens and a collimating optical unit need to be added to the free beam section, which also requires a high precision alignment. Active coupling (active alignment) is a prior art for positioning a glass fiber for optical coupling, wherein a mechanical clamp moves the glass fiber in space while coupling in light at one end of the glass fiber using a laser and monitoring the output signal using a photodiode. The higher the power in the photodiode, the better the coupling. If the coupling is satisfactory, the clamp is fixed and the glass fiber is adhesively bonded. This process comes with several drawbacks, on the one hand, it is very time consuming; on the other hand, it is susceptible to continuous wear of the facility; furthermore, it involves a permanent adhesive bonding of the glass fiber which is mechanically problematic; finally, the optical path of the optical component has to be accessible in order to be able to measure the signal coupled in on the photodiode. Another possibility to realize a direct coupling of a glass fiber on a chip without active coupling is the use of a V-etched groove on the chip (V-groove), i.e. the glass fiber is aligned by the mechanical boundaries of the groove with respect to the waveguide on the chip when inserted. However, this process requires a higher effort on the chip side. The mode field matching has to be done on the chip and the groove requires valuable chip surface. Furthermore, this coupling form requires very narrow tolerances of the glass fiber diameter in the production of the groove, which cannot be provided in practice in general.

[0005] In general, it is advantageous to perform the coupling of the glass fiber to the optical component non-actively, i.e. without optimizing the signal by measuring the light passing through the glass fiber on a detector, especially in terms of effort and speed of the process. Passive coupling requires a very precise measurement of the coupling point positions of the light entrance and light exit of the glass fiber and the optical component, e.g. a PIC, and based on this measurement information an optical connection between the glass fiber and the optical component is established. Determining the position and orientation of the glass fiber core in space is often obstructed because the end face of the glass fiber cannot be accessed and / or the glass fiber is embedded in a glass fiber array.

[0006] If a free form waveguide is used as an alternative to active coupling, an optical connection between the two optical components is established by using direct write 3D lithography. For this purpose, a precise determination of the position and orientation of the optical components is also required. A further difficulty in this process is that the glass fiber has to be detected when it is mounted in the facility for two-photon lithography. Therefore, these are only limited options to look at the glass fiber from various sides by using classical imaging methods. Usually, the facilities for two-photon lithography only comprise the option to look at the optical components and / or the glass fiber from above using a camera or to scan them using a laser beam.

[0007] Especially when using direct-write two-photon lithography, it is often necessary to determine the precise position and orientation of one or more objects, mainly in order to write at least one optical element on the object in a precisely aligned manner. Applications can be chosen in particular from detecting the position and orientation of waveguides, coupling points or the surface of optical components, preferably glass fibers, optical chips or lasers. According to the prior art, for this purpose imaging methods are used, preferably cameras which can record images through the objective of the lithography system and which can determine information about the position and orientation through suitable processes, in particular by recording the optical components (focal stack) in different cross-sectional planes. In principle, optical elements such as glass fiber cores can be detected based on the refractive index difference between the glass fiber core and the glass fiber cladding by using a microscope or by using the optical units in a direct-write lithography system, but an undefined background illumination, which can occur in particular with non-transparent structures, can lead to a low signal-to-noise ratio, resulting in a low level of reproducibility. In addition, for complex arrangements of glass fibers, for example in a trench with a V-shaped cross-section (V-groove), the behavior of the signal cannot be unambiguously determined, so that detection by classical imaging in a microscope can only be carried out to a very limited extent here.

[0008] According to the prior art, in order to determine the precise position and orientation of glass fibers, for example in a fusion device, special illumination is often used. US 4,492,463 A discloses that for this purpose a glass fiber is illuminated from one side and the deflection of the light at the opposite side by the glass fiber is detected in transmitted light, wherein the glass fiber or the associated glass fiber core acts as an optical lens here. However, this method can only be used when the glass fiber can be optically accessed from both opposite sides. This is often not the case in optical components which are assembled in particular as finished products, since the glass fibers are usually attached to metal or silicon substrates here. Glass fiber arrays are further encumbered by the fact that they are adhesively bonded in glass blocks for the purpose of facilitating handling. The glass blocks can distort the course of the light, thus hindering the recognition of the glass fibers in transmitted light. In lithography systems for establishing photonic connections, positioning stages or platforms are often used on which the optical components which are intended to be connected are placed. Cameras attached on opposite sides can greatly limit the size of the optical components. In addition, a high level of effort is required to arrange the cameras in such a way that they can be mechanically moved in the integrated structure, so that a higher level of wear of the lithography system is to be expected.

[0009] US 4,506,947 A or US 4,690,493 A disclose the use of ultraviolet light to irradiate a glass fiber and to excite fluorescence associated with the glass fiber core, wherein the fluorescence thus generated is evaluated. However, this method can only be used if the optical component can withstand ultraviolet radiation. This is not possible if a 3D lithography with a UV-sensitive photoresist is used, since the photoresist would cure under UV irradiation. A further limitation of this method is that a fluorescence difference must exist between the glass fiber core and the glass fiber cladding.

[0010] Furthermore, methods are known for detecting objects using a confocal microscope. D. B. Hovis & A. H. Heuer, Use of laser scanning confocal microscopy (LSCM) in materials science , Journal of Microscopy 140, pages 173-180, 2010, describe a classic confocal microscope, the focus of which can be moved by using a galvanometer scanner. In a classic confocal microscope or a laser scanning confocal microscope, image data is generated by scanning a surface using the focus, with the surface reflection of the object or the fluorescence of the object to be detected or its surroundings. A classic confocal microscope can also be used in a direct write lithography system; for this purpose, a confocal measurement can be carried out using the exposure laser, wherein a laser intensity below the polymerization threshold is usually chosen. Thus, it is possible to detect the surface of an optical component, for example a waveguide, or an associated coupling point, for example in an optical chip or a laser. If the object has a certain reflectivity, it is possible to detect objects with and without topography, such as optical components or substrates, using confocal scanning. However, the problem that arises with a simple confocal scan using a light beam focused on the surface of a glass fiber is that the lateral position of the glass fiber axis cannot be determined accurately enough, since the captured backscatter signal drops very rapidly when the focus is moved away from the glass fiber perpendicular to the glass fiber direction. Furthermore, if only a part of the glass fiber surface is scanned and the radius of the object is determined by fitting, this leads to inaccurate detection. Furthermore, for cylindrical objects made of transparent material, the rotational axis cannot be detected with high accuracy.

[0011] If an optical component, such as a glass fiber, is embedded in a medium that has two-photon fluorescence when illuminated with light, the position and orientation of the glass fiber can be detected by scanning the (part of) the volume surrounding the glass fiber with a laser, in particular the exposure laser of a lithography system, at low power. The transition between the presence and absence of fluorescence defines the boundary surface of the glass fiber via which the extension of the glass fiber can be determined. If these data are known, the radius and position of the glass fiber can be determined. However, this method is intrinsically slow, since a large volume has to be scanned. Furthermore, if only a part of the glass fiber is scanned and the radius is determined by fitting, this leads to inaccuracies in the detection. For this purpose, the radius of the glass fiber must be as uniform as possible, since otherwise additional inaccuracies occur. Furthermore, it is also necessary that there is fluorescent material outside the glass fiber.

[0012] 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) describes the theoretical three-dimensional distribution of the backscattered signal produced when recording a reflecting sphere using a confocal microscope and compares it with the corresponding measurement. However, this publication does not describe a method for determining the spatial position of an object, in particular a sphere. Furthermore, back reflection of non-spherical objects is not considered here, which is necessary for detecting a cylindrical glass fiber.

[0013] Y. Xiao, L. Qiu and W. Zhao, Laser confocal cylindrical radius measurement method and its system Applied Optics 56 (23), 2017 describes the confocal characterization of a hollow cylinder. For this purpose, a cylindrical phase wavefront is radiated onto a cylindrical test object, wherein the property of a part of the surface of the cylinder acting as a retroreflector when the illumination light field is focused on the center point of the cylinder is utilized. However, in this structure the position is precisely known a priori and the measurement serves only to determine the radius of the cylinder. Furthermore, only a hollow cylinder is used as test object.

[0014] 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 sensorProceedings of IEEE International Workshop on Metrology for Industry 4.0 & IoT, 2018, describes the use of chromatic confocal detectors to characterize the radius of a hollow cylinder. In the described method, the orientation of the axis of the hollow cylinder relative to the measurement system is determined in order to automatically place the detector centered in the hollow cylinder. For this purpose, the chromatic confocal sensor is placed inside the hollow cylinder and rotated. The chromatic confocal sensor determines the distance to the cylinder in a certain direction, which determines the rotation of the sensor within the cylinder and the spatial position of the axis of the hollow cylinder. However, this method requires the light source to be rotated inside the object and is therefore only suitable for hollow cylinders. Furthermore, the light source is rotated around the axis of the glass fiber to determine the spatial position of the glass fiber within the optical arrangement, which is very difficult to implement.

[0015] J. H. Burge, Fizeau interferometry for large convex surfaces SPIE Vol. 2536, pages 127 to 138, 1995, describes the structure of a special Fizeau interferometer. Here, a spherical reference surface is used to determine the surface quality of a test object by using an interferometric measuring device. The spatial position of the object is not described here and cannot easily be determined by this setup.

[0016] Object of the invention Starting from this, the object of the present invention is to provide a method and a device for determining the spatial position of a non-spherical object and an associated computer program which at least partially overcome the disadvantages and limitations listed in the prior art.

[0017] In particular, the present invention aims to achieve as accurate as possible a determination of the spatial position of an object, in particular a glass fiber, especially when the object, in particular the glass fiber, is located in a position which is difficult to access on a substrate and / or in a position which is difficult to access inside a facility for two-photon lithography. Here, the spatial position of the object should be determined even if the object is at least partially surrounded by photoresist. Furthermore, the spatial position of the object should be determined even if the accessible detection volume is very small. Furthermore, the optical unit for detecting the object position should largely correspond to the optical unit for exposing the object, in particular in order to reduce potential errors and shifts between the manufacture of the object and the detection of the object. Summary of the invention

[0018] This object is achieved by a method and a device for determining the spatial position of a non-spherical object and an associated computer program having the features of the independent claims. Advantageous improvements which can be implemented individually or in any combination are set out in the following description and the dependent claims.

[0019] In a first aspect, the present application relates to a method for determining a spatial position of a non-spherical object having at least one surface portion of known shape. The term "object" herein refers to an extended object having a surface accessible by the present method, which can be a living or non-living object. 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 a glass fiber. The term "glass fiber" herein refers to a cylindrical object comprising a glass fiber core and a glass fiber cladding configured as an optical fiber by exploiting the optical refractive index difference between the glass fiber core and the glass fiber cladding for efficient guiding of light.

[0020] The term "spatial position" refers to a specification of the location in space with respect to the extended object, in particular in the form of values with respect 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 other coordinate systems is also conceivable. Generally, the spatial position of an object can consist of a position of the object and an orientation of the object. The term "position" herein refers to the location in space of a certain point on the object, in particular a center point or a focal point, while the term "orientation" indicates the direction in which an axis of the object, in particular a longitudinal axis of a cylindrical object, preferably a glass fiber, is aligned.

[0021] The method for determining a spatial position of a non-spherical object having at least one surface portion of known shape according to the present application comprises the following steps: a) radiating at least two light fields onto the object by means of an objective, wherein each light field has a known phase front, wherein the phase fronts of the at least two light fields differ from each other at least after the objective, wherein the curvature of the phase front at the exit window of the objective is smaller than the minimum curvature of the surface portion of the object in at least one spatial direction, wherein for at least one of the light fields there is at least one line in the surface portion along which at least two local surface normals of the surface portion are orthogonal to the phase front of the at least one of the light fields; b) detecting reflection components of the at least two light fields originating from the object by using a detector; and c) determining the spatial position of the non-spherical object from the detected reflection components of the at least two light fields in view of an expected backscattering signal resulting from the surface portion of known shape.

[0022] The steps of the method can preferably be carried out in the order specified, starting with step a), followed by step b) and ending with step c), wherein one or more steps, in particular consecutive steps, can also be carried out at least partially simultaneously. In a preferred embodiment, steps a) and b) of the method can be repeated using a large number of different light fields generated in time succession, which have mutually different phase fronts, respectively. The term "in time succession" here refers to a temporal sequence according to which the individual light fields are generated and radiated onto the object in time succession. The time interval between two temporally successive light fields is preferably 0.1 ps to 100 ms, particularly preferably 1 ps to 100 ps; however, other time intervals can also be used. In an alternative embodiment, at least two of the light fields in step a) can be radiated simultaneously if the detector used according to step b) is configured to detect the respective reflection components originating from the at least two light fields of the object in a position-resolved manner. Independently of the embodiment chosen, the determination of the spatial position of the object can preferably be completed within 30 seconds, particularly preferably within 10 seconds.

[0023] According to the application, the spatial position of an aspherical object is determined by scanning a surface portion of the object using at least two light fields according to step a) whose phase fronts differ from one another at least after the objective. The at least two light fields can still be identical before the objective, whereas according to the application they differ from one another after the objective. The specification "after the objective" here refers to the direction along the propagation direction of the at least two light fields. As described in more detail below, in a particular embodiment, the difference between the phase fronts after the objective can be produced by moving the objective in the z direction, wherein the position of the at least one galvanometer scanner in the xy plane remains unchanged. However, other embodiments for producing the required difference between the phase fronts after the objective can also be envisaged.

[0024] The term "light field" here refers to a spatially extended light beam, which is preferably present in the form of a collimated light beam, wherein the term "spatially extended" indicates that the light beam has a diameter, preferably a diameter of 0.1 mm to 100 mm, more preferably a diameter of 1 mm to 20 mm. The "scanning" of the surface portion of the object is achieved by focusing the at least two light fields, respectively, using an objective, so that mutually different phase fronts, preferably substantially spherical, are incident on the surface portion of the object. The scanning of the surface portion of the object can preferably be carried out using 2 to 2,000,000, more preferably 50,000 to 750,000 light fields having mutually different phase fronts; however, other numbers of light fields can also be used.

[0025] The term "surface portion" relates to a portion of the surface of an object which extends, the geometry of which, referred to as "shape", is known. The shape of the surface portion can be characterized here by using a local surface normal, wherein the term "surface normal" refers to an imaginary vector which is orthogonal to the outer surface of the surface portion. The term "orthogonal" here refers to an angle of 90° ± 1°, preferably 90° ± 0.1°. In a particular embodiment, the surface portion of which the shape is known can comprise the entire surface of the object. Alternatively or additionally, the distribution of the reflection components of at least two of the light fields over the entire surface of the object can be known, modeled or estimated. The term "spherical" here refers to a phase wave front which represents a portion of a spherical surface. The term "substantially" here includes a deviation of the total surface of the phase wave front from the portion of the spherical surface of at most 10%, preferably at most 1%.

[0026] The term "surface portion of which the shape is known" here refers to the fact that basic information about the spatial form of the surface portion is present. It is not necessary for this purpose to know the shape or all of its parameters in detail. In an embodiment in which the surface portion has a cylindrical shape, the method for determining the spatial position of an aspherical object according to the application does not require knowledge of the diameter of the object; it is sufficient to know the information that there is a cylindrical shape. Alternatively or additionally, the basic information about the spatial form of the surface portion can also be determined indirectly, preferably by using the detection according to the application and additional ex situ measurements according to a further method, preferably in such a way as to establish the relative position between the maximum in the detected light field and the surface portion.

[0027] The term "phase wave front" refers to an imaginary surface on which all points have the same phase, wherein the phase wave front moves in the direction of the surface normal of the phase wave front with the speed of light. The phase wave fronts which are different from one another and which are incident on the surface portion of the object at the same time or, preferably, in time succession after the objective, can preferably be generated by moving the focal point of the light field using a device configured for this purpose, preferably in all three spatial directions. Here, at least one of the light fields in the light field (preferably in the beam path before the objective) can be changed accordingly. For this purpose, at least one galvanometer scanner can preferably be used. Alternatively or additionally, a relative displacement between the objective and the object can take place between the radiation of at least two of the light fields. For this purpose, at least one element configured for the displacement of the object and / or the objective can be used, preferably at least one element selected from the group consisting of a positioning stage, which can preferably be operated piezoelectrically, or by using an inductive element, in particular a voice coil. The term "phase wave fronts which are different from one another" refers to the fact that there is a difference in the phase wave front with respect to the object, in particular the surface portion of the object.

[0028] Furthermore, alternatively or additionally, the change of the at least one light field in the light field can be performed by using a diffractive element. The diffractive element can in particular comprise a digital light modulation element having a plurality of individually actuatable optical elements configured to modulate an incident light beam. The digital light modulation element can preferably have a spatial light modulator or a digital micromirror unit. The term "spatial light modulator" (SLM) refers to an optical device configured to impose an intensity pattern, in particular in the form of a spatial modulation of the amplitude and / or phase, onto an incident light beam, wherein the intensity pattern can be imposed electronically and / or optically. A digital micromirror unit (DMD) is a device having a large number of tiltable micromirrors arranged in a matrix, the edge length of which is in the micrometer range, wherein each micromirror can be individually adjusted by using an electrostatic field.

[0029] Due to the relative change of the focal position with respect to the object, the phase wave front, which is preferably substantially spherical, can be incident to the surface portion of the object from different directions and with different curvatures. Furthermore, if according to step a) the curvature of the phase wave front in at least one spatial direction corresponds to the curvature of the surface portion in the same spatial direction, or there is at least one line in the surface portion along which at least two local surface normals of the surface portion are orthogonal to the phase wave front of the light field currently imposed to the surface portion, an important component of the light field incident on the object is reflected back to itself as a reflection component of the at least two light fields. The term "reflection" here refers to a process in the course of which a component of a light field is incident on a surface, wherein a change of the phase wave front of the light field occurs such that a superposition with the light field incident on the surface takes place. The term "curvature" refers to a local deviation of the surface course from a plane in at least one dimension. Furthermore, the term "line" refers to a spatially arranged imaginary course; in the present case, the term "line" refers to a spatially arranged imaginary course of the at least two local surface normals on the surface portion observed, which are orthogonal to the phase wave front of the light field currently imposed to the surface portion.

[0030] In order to cause the individual light fields to be reflected on the object, a refractive index difference between the object and the medium surrounding the object can exist. Here, a refractive index difference < 0.2, preferably a refractive index difference < 0.1, can be sufficient to generate a detectable backscattering signal. In particular, if the object is a transparent object or a translucent object, the reflection components of the at least two light fields originating from the object can be generated at a surface portion of known shape and at an internal boundary surface inside the object. Here, at the internal boundary surface inside, there are two local surface normals of the surface portion which are orthogonal to the phase wave front of the light field currently imposed to the surface portion. In a particular embodiment, detection can be carried out using the reflection of the at least two light fields at both the surface and the internal boundary surface.

[0031] Alternatively, the object can be an opaque object, preferably by coating the object at least in the region of the surface portion. In this embodiment, the reflected components of the at least two light fields originating from the object can only be generated at the surface portion of the known shape. If the illumination field is completely reflected before propagating through the focal region, there is no real focal region. Here, the virtual focal region can be regarded as a hypothetical focal region of the unreflected light beam. However, even if only a virtual focal region is present, the spatial position of the object, in particular the symmetry axis of a cylindrical object, can be determined. The coating of at least the surface portion of the object can preferably be carried out by using metallization or by using a deposited dielectric stack (Bragg mirror); however, another process can also be used alternatively or additionally. This embodiment can in particular be advantageous, since by an opaque coating of at least the surface portion of the object a higher signal contrast can be obtained.

[0032] In a particularly preferred embodiment, the spatial position of a cylindrical object, in particular a glass fiber, is determined according to this embodiment, the curvature of the essentially spherical phase front only corresponds to the curvature of the object in the spatial direction when the focal region is located in the center of the cylinder. The term "focal region" here refers to the volume around the focal point within which the irradiation intensity exceeds a specified intensity threshold. This intensity threshold can here 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, another value can also be used.

[0033] In a particularly preferred embodiment, the at least two local surface normals of the surface portion can be orthogonal to the phase front of the light field currently applied to the surface portion, wherein the distance between the focal point and the surface portion preferably corresponds to at least twice the diameter of the focal region, particularly preferably at least five times the diameter of the focal region.

[0034] According to step b), the reflected components of the at least two light fields originating from the object are detected using a detector, preferably a confocal detector. For this purpose, the reflected components of the at least two light fields are detected for the at least two light fields having mutually different phase fronts. For this purpose, a beam splitter can be used to decouple the reflected components of the at least two light fields from the beam path common to the components of the light fields incident on the object to generate the light field incident on the detector; however, at least one other optical element or another type of beam path suitable for this purpose can also be used.

[0035] In a particularly preferred embodiment, the detector can comprise a focusing optical unit configured to focus the light field incident on the detector on an optical stop before it is incident on the photodetector. In an alternative embodiment, the confocal detector can comprise a glass fiber instead of an optical stop, which is configured to guide the light field incident on the glass fiber onto the photodetector.

[0036] In a further embodiment, the detector can detect the backscattered signal from a plurality of positions in a position-resolved manner. This embodiment is particularly advantageous, in particular when at least two of the light fields are simultaneously illuminated in step a).

[0037] However, further embodiments of the detector are also conceivable.

[0038] In a particular embodiment, the detection of the reflected components of the at least two light fields originating from the object can be carried out synchronously with the generation of the temporally successive light fields. As soon as a newly formed light field with a different phase front than the preceding light field is radiated onto the object, the detection of the reflected components of the at least two light fields originating from the object can be carried out again. The term "synchronous" therefore refers to a temporal coordination between steps a) and b) (preferably additionally including step c)), i.e. a temporal coordination between the generation of the light fields according to step a) and the illumination of the selected light field onto the object and the detection of the reflected components of the selected light field originating from the object by using the detector according to step b), and preferably a temporal coordination between the determination of the spatial position of the object from the detected reflected components of the selected light field according to step c). However, other embodiments are also possible.

[0039] If the shape of the surface portion and the phase front of the illumination are known, the spatial position, i.e. the position and the orientation, of the object is thus determined according to step c). By repeatedly carrying out steps a) and b), information about the intensity of the components reflected from the object in each of the illuminated light fields with a different phase front can be obtained. When there is at least one line located in the surface portion along which at least two local surface normals of the surface portion are orthogonal to the phase front of at least one of the light fields, the light field intensity detected in the detector is highest. From the signals detected by the detector, together with the associated irradiated light fields and phase fronts, it can be determined which of those signals have the highest intensity. The respective associated phase front then represents individual surface portions, the combination of which enables the position and the orientation of the object to be detected.

[0040] In a preferred embodiment, the focusing component of the light field can first be deflected laterally, i.e. in a direction perpendicular to the propagation direction of the light field, in two dimensions and the reflection signal for each point is recorded on this surface unfolded in two dimensions. The focal point is here preferably located inside the cylindrical object, particularly preferably near the axis of rotation of the cylindrical object. The spatial scan rate is preferably 10 nm to 10 pm, particularly preferably 50 nm to 500 nm. Here, the reflection signal strength detected in the detector can preferably be stored together with the associated position of the focal point. The focal point can then be displaced in the propagation direction of the light field, preferably by 10 nm to 10 pm, particularly preferably by 50 nm to 500 nm, so that a further surface perpendicular to the propagation direction can be scanned and the intensity values stored together with the position of the associated focal point. By further repeating this procedure, the focal point can scan the volume layer by layer. From the stored data of the scanned volume, those focal points or focal point groups can now be determined whose intensity is highest. The expression "highest intensity" here means an intensity above a defined intensity threshold. The positions of these focal points correspond essentially to the desired spatial position of the central axis of the cylindrical object. The term "essentially" here includes a positional deviation of the central axis of the cylindrical object of better than 1 pm, particularly preferably better than 500 nm, and a directional deviation of preferably better than 1°, particularly preferably better than 0.5°, relative to the actual spatial position of the central axis of the cylindrical object, which can in particular be determined by a calibration experiment of the method using other methods and devices.

[0041] Methods from industrial image processing can preferably be applied to determine the highest intensity. Here, an edge recognition can be carried out on each scanned surface to determine the focal points or focal point groups from their surroundings on the respective surface. From this, the symmetry axis of the cylindrical object in this surface or in the region of this surface with the highest light-dark contrast can preferably be determined.

[0042] In a particularly preferred embodiment, the present application enables the determination of the position and orientation of a glass fiber by scanning the volume within the glass fiber with a focused light field perpendicular to the axis of rotation, wherein the detection is preferably performed using a confocal detector. The glass fiber can be part of an arrangement comprising further optical components besides the glass fiber. The arrangement can be configured such that photonic wire bonds or micro lenses can be introduced as optical connections between the glass fiber and the further optical components by using a direct write lithography method. For this purpose, a part of the glass fiber and / or a part of the arrangement can be embedded in a photoresist. By a corresponding arrangement of the light source, the objective, the object and the detector, only those light beams can be detected with the detector which intersect the center of the glass fiber and thus are guided through the core of the glass fiber. In other words: During the scanning of the partial volume, the backscattered signal detected with the detector can reach an amplitude maximum when the focal region is located in the center of the glass fiber, i.e. in the core of the glass fiber. In this embodiment, for this purpose, not the surface of the glass fiber is scanned, but the interior of the glass fiber, thereby achieving a higher detection accuracy. After the detection, the photonic wire bonds or micro optical components can be manufactured in situ using the same light source and the same objective.

[0043] In a further aspect, the present application 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-transitory, computer-readable medium. The term "non-transitory, computer-readable medium" or "computer-readable data carrier" here refers to a non-volatile data storage medium, such as 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-transitory, computer-readable medium can preferably contain instructions which, when executed by a computer or computer network, cause the computer or computer network to control and / or perform at least step c), preferably all steps, of the method for determining the spatial position of a non-spherical object according to the present application in order to determine the spatial position of the non-spherical object.

[0044] In a further aspect, the present application relates to an apparatus for determining the spatial position of a non-spherical object, the non-spherical object having at least one surface portion of a known shape. Herein the apparatus comprises: - at least one light source, which is configured to generate at least two light fields, wherein each light field has a known phase wave front, wherein the phase wave fronts of the at least two light fields differ from each other at least after an objective, wherein a curvature of the phase wave front at an exit window of the objective is smaller than a minimum curvature of a surface portion of the object in at least one spatial direction, wherein for at least one of the light fields there is at least one line lying in the surface portion along which at least two local surface normals of the surface portion are orthogonal to the phase wave front of the at least one of the light fields; - at least one objective, which is configured to radiate the at least two light fields onto the object; - at least one detector, which is configured to detect reflected components of the at least two light fields originating from the object; and - at least one evaluation and supervision unit, which is configured to determine a spatial position of the aspherical object from the detected reflected components of the at least two light fields in view of an expected backscattering signal produced by the surface portion of known shape.

[0045] The term "evaluation and supervision unit" refers to a unit which is configured to receive, process and output data. Here, this can preferably be an electronically or optoelectronically controllable unit, which can in particular have a computer, a microcomputer or a programmable chip, such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA), wherein the evaluation and supervision unit can have access to one or more computer programs which can be configured to carry out the methods described herein. Alternatively or additionally, the evaluation and supervision unit can be comprised by a mobile communication device, in particular a smartphone, a tablet or a laptop. However, other embodiments of the evaluation and supervision unit are also conceivable, for example the integration of the evaluation and supervision unit into a server. However, it is not required here that the evaluation and supervision unit is located in the same space or the same surroundings as the other components of the device; by using a computer network, the evaluation and supervision unit can also be arranged in another space, another building, another city, another country or another continent.

[0046] Further details regarding the device and the computer program refer to the description of the method according to the invention.

[0047] Advantages of the invention The invention solves the problem of determining the position and orientation of an object, in particular a glass fiber, which is preferably introduced into a lithography system, in space as accurately as possible. Here, the position and orientation of an object in space can be determined by using an optical method, wherein the shape of at least one surface portion of the object is known. In particular, by using the invention the rotational axis of a cylindrical, transparent or non-transparent object can be reliably detected. Here, the object to be detected can be fixed on a non-transparent carrier and / or approached from a limited carrier from different spatial directions. Thus, the object can generally not be accessible from all sides, but can only be illuminated with a light field essentially from one spatial direction and its back reflection can be observed. Advantageously, the position and orientation of the object in space can be determined independently of any background illumination or stray light of the surroundings.

[0048] By the invention, objects surrounded at least partially by photoresist can also be detected. Furthermore, the detection of the object can also be carried out in the case of very small accessible detection volumes, preferably 300 pm x 300 pm x 300 pm or less, in particular 80 pm x 80 pm x 80 pm or less; for glass fibers, a detection volume of 200 pm x 200 pm x 200 pm or less, in particular a detection volume of 40 pm x 40 pm x 40 pm or less can also be sufficient for reliable detection. The invention also enables the setup and use of a two-photon lithography system, such that the optics for detecting the position of the object largely corresponds to the optics for exposure to manufacture the object. In particular, the laser, typically femtosecond pulses, in the lithography system, the galvanometer scanner and the objective can be used to generate at least two of the light fields. This type of setup in particular minimizes potential errors and shifts between the manufacture of the object and the detection of the object.

[0049] Using the invention, the position of the object in space can be determined robustly independently of the type of optical setup and the surroundings of the object. In particular, the position of the object can thereby be detected with an accuracy of preferably better than 1 pm, in particular preferably better than 500 nm, and the orientation can be detected with a deviation of preferably better than 1 °, in particular preferably better than 0.5 °. In this way, a particularly low-loss coupling of a glass fiber whose spatial position is determined using the invention can be achieved. Although the image field of the optics of the lithography system for detecting the glass fiber is limited when the glass fiber is used in a high-resolution lithography system, the invention enables the detection of the glass fiber using the same optical system that is also used for lithography.

[0050] In particular in optical assemblies where objects are mounted on assembly carriers, optical detection can be performed by using the present application, although the objects are difficult to access (because the objects are either mounted on a sample or access cannot be ensured due to process machines) and although the lighting conditions are poor. The present application is particularly suitable for industrial use, because it enables fast measurements, reaching a short cycle time, and thus enables to save work and costs in this way without reducing the accuracy of the measurement. In addition, the method is suitable for the detection of general objects, so it is also not dependent on whether the object or the environment around the object fluoresces for the detection.

[0051] Furthermore, for the detection of the object, it is not necessary to measure the surface of the object separately or to determine it by an approximation method, in particular a fitting. In particular in the case of a cylindrical object, in the method according to the present application, the backscattering signal is maximum when the focus is on the axis of the object to be detected. By this way a high precision of the detection can be achieved.

[0052] The terms "have", "comprise", "include" or "contain" or any grammatical variants thereof as used herein are used in a non-exclusive way. Thus, these terms can both refer to a situation in which, besides the feature introduced by these terms, no further features are present in the entity described in this context and to a situation in which one or more further features are present in one or more of the entities described in this context. For example, the expressions "A has B", "A comprises B", "A includes B" or "A contains B" can both refer to a situation in which, besides B, no other element is present in A (i.e. a situation in which A consists only of B) and to a situation in which, besides B, one or more further elements are present in A, such as element C, elements C and D, or even further elements.

[0053] Furthermore, it is noted that the terms "at least one" and "one or more" and grammatical variants thereof, when used in conjunction with one or more elements or features, generally only use the respective term "at least one" or "one or more" once when introducing the element or feature. When the element or feature is mentioned again, the respective term "at least one" or "one or more" is generally not used again, but this does not limit the possibility that the element or feature can be provided once or more than once.

[0054] Furthermore, the use of "preferably", "more preferably", "particularly", "for example" or similar terms in this text are used to describe optional features and not to limit alternative embodiments. Thus, features introduced by such terms are optional features and do not by themselves limit the scope of the claims and the independent claims, in particular. Thus, the application can also be performed in other embodiments which do not exhibit all of the features of the preferred embodiments. Likewise, the use of "in an embodiment of the application" or "in an exemplary embodiment of the application" is not meant to limit alternative embodiments or the independent claims in any way. Furthermore, these introductory phrases do not limit all possibilities of combining features introduced by such phrases with other features, whether they are optional features or not. BRIEF DESCRIPTION OF DRAWINGS

[0055] The following description of preferred exemplary embodiments will lead to further details and features of the present application, particularly in connection with the dependent claims. Herein, individual features can be realized individually or several of them can be realized in combination with each other. The present application is not limited to the exemplary embodiments. The exemplary embodiments are schematically represented in the following figures. Herein, identical reference signs in the figures represent identical or functionally identical elements or elements which correspond to each other in their function. In the specific figures: Fig. 1 shows a schematic representation of an exemplary embodiment of an apparatus for determining a spatial position of a non-spherical object; and Figure 2 Fig. 1 shows a schematic representation of an exemplary embodiment of an apparatus for determining a spatial position of a non-spherical object; and DETAILED DESCRIPTION

[0056] Fig. 1 shows a schematic representation of an exemplary embodiment of an apparatus 10 for determining a spatial position of a non-spherical object 110 having at least one surface portion 111 of a known shape, wherein the shape of the surface portion 111 can be characterized by using a local surface normal 112. Herein, the non-spherical object 110 is exemplarily shown as a cylindrical object, particularly as a glass fiber, wherein any portion of the cladding of the cylindrical object, particularly of the glass fiber, can be used as the surface portion 111 of a known shape. In a particularly preferred embodiment, the detection of the position of the glass fiber can be performed within a lithography system. Herein, the position and orientation of the glass fiber core of the glass fiber to be detected in three-dimensional space is to be determined. The glass fiber can preferably be part of an optical setup, whereby an accessibility from all spatial directions can be limited. In particular, the front end face of the glass fiber can not be accessible by the imaging optical system. However, as long as the shape of another shaped object 110 in at least one surface portion 111 is known, this object can also be examined.

[0057] The exemplary apparatus 10 shown schematically in Fig. 1 comprises a light source 50, a beam splitter 60, an optional galvanometric scanner 75, an objective 70 and a detector 80. The light source 50 is configured to generate a light field 100 which is guided on the Figure 1A indicated beam path onto the objective 70. According to Figure 1A The coordinate system 120 shown schematically as well, for this purpose the light field 100 is guided in the z-direction. The light source 50 can preferably be embodied as or comprise a laser, in particular a femtosecond laser (fs-laser). In one particularly preferred embodiment, the light source 50 can be configured as an exposure laser of a lithography system at the same time. In this way, detection and writing can be carried out at exactly the same location; calibration errors or imaging errors can be automatically compensated. The wavelength of the light source is preferably between 300 nm and 3000 nm, particularly preferably between 500 nm and 1500 nm. However, other types of light sources 50 can also be used.

[0058] The objective 70 is configured to generate a focal component 101 from the light field 100 generated by the light source 50, which is focused on a focal point 103 surrounded by a focal region. In Figure 1A the illustration, the focal point 103 is a real focal point located inside 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 before the objective 70, so that the focal region surrounding the focal point 103 produced by the objective 70 is adjusted in a lateral direction. According to the coordinate system 120 shown schematically, the lateral direction 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 specified by the evaluation and supervision unit 150.

[0059] As an alternative or in addition to the galvanometric scanner 75, the light field 100 generated by the light source 50 can be influenced by displacing the objective 70, in particular by using a positioning stage which is preferably operated in a piezoelectric manner, or by using an inductive element, in particular a voice coil. This alternative is shown schematically in particular in Figure 1B and Figure 1C It is also conceivable to influence the light field 100 generated by the light source 50, preferably by using a diffractive element (not shown). This diffractive element can in particular comprise a digital light modulation element explained in more detail above, in particular the diffractive element is a spatial light modulator or a digital micromirror unit.

[0060] In a preferred embodiment, the object 110 is transparent or at least translucent with respect to the incident light field 110, such that the focused component 101 of the light field 100 generated by the objective 70 can enter the interior 113 of the object 110 in the region of the surface portion 111 of known shape. In particular due to the difference in refractive index between the material located in the interior 113 of the object 110 and the material surrounding the object 110, a portion of the focused component 101 of the light field 100 generated by the objective 70 is reflected at the inner boundary surface 114 of the object 110 and thus generates the reflected component 102 of the light field 100. The material at least partially surrounding the object 110 can in particular be selected from air, an adhesive (which can also be configured for fastening the object), an immersion medium for an objective having a high numerical aperture NA (in particular, a numerical aperture NA > 1), or a photoresist (which can also be configured as an immersion medium).

[0061] In an alternative embodiment (not shown), the object 110 can comprise a substance which is not transparent with respect 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 which is not transparent with respect to the incident light field 100, such that the reflected component 102 of the light field 100 is generated according to the reflection of the focused component 101 of the light field 100 generated by the objective 70 at the relevant surface portion 111 of the object 110. In this embodiment, the beam path of the interior of the object 110 in Fig. 1 (including the focal point 103) should be considered virtual. If the light field 100 is completely reflected before it propagates through the focal region, there is no real focal region; in this embodiment, the virtual focal region can be considered as a hypothetical, unreflected focal region of the light field. This embodiment can in particular have the advantage that an increase in signal contrast can be achieved by opacifying at least the surface portion 111 of the object 110. The coating of at least the surface portion 111 of the object 110 can preferably be produced by using metallization; however, other processes can also be used alternatively or additionally.

[0062] As Fig. 1 additionally shows, the component 101 of the light field 100 generated by the light source 50 and focused by the objective 70 comprises a known phase wavefront 104, which is schematically shown as a dashed line. In the embodiment shown, the phase wavefront 104 is substantially spherical, wherein the curvature of the substantially spherical phase wavefront 104 at the exit window of the objective 70 is smaller than the minimum curvature of the surface portion 111 of the object 110 in at least one spatial direction (in particular, the direction along the z-axis in Fig. 1). In this way, in particular for a substantially spherical phase wavefront 104, a working distance suitable for carrying out the present method can be provided between the objective 70 and the surface portion 111 of the object 110.

[0063] As additionally shown in Fig. 1, the beam splitter 60 is configured to direct the reflected component 102 of the light field 100 in the direction of the detector 80, which forms a light field 105 incident on the detector 80. In particular, in order to obtain as high a spatial resolution as possible, the detector 80 can embody a confocal detector. For this purpose, the detector 80 can have a focusing optical unit (not shown) which focuses the light field 105 incident on the detector 80 on an optical stop before the light field 105 is incident on a photodetector. In an alternative embodiment, the confocal detector can comprise a glass fiber (not shown) instead of an optical stop, which is configured to guide the light field 105 incident on the glass fiber onto a photodetector.

[0064] It is advantageous to use the objective 70 shown by way of example in Fig. 1 as a common optical element which is configured both for illuminating the object 110 and for detecting the reflected component 102 of the light field 100, in particular because any aberrations in the objective 70 can thus be automatically corrected, so that an additional calibration of a second objective can be omitted.

[0065] According to the application, the surface portion 111 of the object 110 is illuminated in time succession using at least two, preferably a large number of, different light fields 100, each of which has a known phase wave front 104, wherein the phase wave fronts 104 of the at least two, preferably a large number of, light fields 100 differ from one another at least after the objective 70. In this way, in particular a "scanning" of the surface portion 111 of the object 110 can be achieved. According to the application, the scanning of the surface portion 111 of the object 110 is carried out until, for at least one of the light fields 100, there is at least one line (not shown) in the surface portion 111 along which at least two local surface normals 112 of the surface portion 111 are orthogonal to the phase wave front 104 of the at least one light field 110.

[0066] A signal is generated in detector 80, the signal being based on light field 105 incident on detector 80, and can be detected and recorded using evaluation and supervision unit 150. Here, the detection and recording of the signal by detector 80 is preferably synchronized with the movement of focus 103. Using an algorithm configured for this purpose, the desired position and orientation of object 110 can be determined based on the signal. As schematically shown in FIG1, evaluation and supervision unit 150 can be embodied as a computer (personal computer or PC) actuated by monitor 152 and / or keyboard 154. Alternatively or additionally (not shown), evaluation and supervision unit 150 can be embodied as an electronic communication unit including monitor 152 and keyboard 154, preferably a smartphone, tablet, or laptop. Monitor 152 may have a display screen 153 on which object 110 and / or the determined spatial position of the object can be displayed. The evaluation and monitoring unit 150 may also have a connection 151, through which the evaluation and monitoring unit can be specifically connected to the light source 50, the galvanometer scanner 75, the detector 80, the monitor 152, and / or the keyboard 154, wherein the connection 151 can be implemented as a wired connection or a wireless connection. As described above, however, it is not required that the evaluation and monitoring unit 150 be located in the same space or environment as other components of the device 10; utilizing a computer network, the evaluation and monitoring unit 150 can also be arranged in another room, another building, another city, another country, or another continent. Other embodiments of the evaluation and monitoring unit 150 are also possible.

[0067] like Figure 1A As shown, when the focal area intersects the axis of symmetry of object 110, the component 101 of the light field 102 focused on the real or virtual focal point 103 is subsequently imaged onto itself. If the focal area is located at the center point 115 of a cylindrical object (especially fiberglass), the inner boundary surface 114 of the cylindrical object 110 acts as a retroreflector, which generates the reflected component 102 of the light field 100, which spatially overlaps with the component 101 of the light field 100 focused on the focal point 103 due to back reflection. By using the beam splitter 60, the reflected component 102 of the light field 100 can be incident on the detector 80 as a light field 105 and can be registered in the detector 80 as a signal intensity.

[0068] However, if the focal area is like Figure 1B and Figure 1C As shown, if the light field 100 component 102, which is actually or virtually located outside the center point 115 of the cylindrical object 110, is reflected at the inner boundary surface 114 of the cylindrical object 110, it will not be imaged onto itself. Therefore, it will be out of focus when it is incident on the detector 80. Due to this situation, the light field 100 component 102 reflected at the inner boundary surface 114 of the cylindrical object 110 will not be imaged onto itself. Figure 1A The signal strength is lower in the situation shown.

[0069] In order to determine the position and orientation of the object 110 in space, at least two, preferably a large number of points are identified in the region of the surface portion 111 at which the surface of the object 110 acts as a retroreflector as good as possible. In order to obtain a large number of points in the surface portion 111, the position of the focal point 103 relative to the center point 115 of the object 110 can preferably be varied. For this purpose, a movable objective 70 and / or a galvanometer scanner 75 as described above can be used, wherein the galvanometer scanner 75 is configured to deflect the light field 110 at variable angles, wherein the individual angles to be set can be specified by the evaluation and supervision unit 150. By determining a plurality of maxima in the light field 105 incident on the detector 80, in particular the axis of the cylindrical object 110 can be determined; for this purpose, no further dimensions of the cylindrical object 110, in particular the radius, need to be known.

[0070] Figure 2 A schematic diagram showing an exemplary embodiment of a method for determining the spatial position of a non-spherical object 110 in space is shown. The objective 70 generates a focused component 101 of the light field from the light field 100. According to steps a) and b), the focal point 103 is first deflected laterally over a surface 201 lying in the xy-plane of the coordinate system 120 by using the galvanometer scanner 75 and the light field 105 incident on the detector 80 is recorded for each point on this surface 201 by using the detector 80. The focal point 103 is preferably located inside the object 110, preferably inside a cylindrical object, in particular a glass fiber. Scanning the surface using the focal point 103 is not necessary. The spatial scanning rate, i.e. the distance between the points 210 in the surface representing the respective focal point 103, is preferably 10 nm to 10 pm, particularly preferably 50 nm to 500 nm. The intensity of the detected reflection signals is stored in the supervision and evaluation unit 150 together with the associated position of the focal point 103. Then, the focal point 103 is displaced in the propagation direction of the light field 100, i.e. in the z-direction, preferably by 10 nm to 5 pm, particularly preferably by 50 nm to 500 nm. The displacement in the z-direction can be carried out by displacing the objective 70. Subsequently, further surfaces 202, 203, 204 in the xy-plane are scanned and the intensity values detected by the detector 80 are stored together with the associated positions of the points 210 representing the respective focal point 103. By further repeating this procedure, the volume is scanned layer by layer by the focal point 103. Now, those focal points 103 or focal point 103 groups can be determined from the data of the scanned volume stored in the supervision and evaluation unit 150 which have the highest intensity. The positions of these focal points 103 substantially correspond to the position of the central axis of the cylindrical object 110. At least one intensity threshold value can be defined here to determine the highest intensity, wherein those intensities which exceed the intensity threshold value having the highest value can be considered the highest intensity.

[0071] Methods in industrial image processing can preferably be applied to determine the highest intensity. Thus, an edge recognition can be performed for each scanned surface 201, 202, 203, 204, in particular to determine the light-dark contrast between a point 210 representing the respective focal point 103 and its surroundings on the associated surface 201, 202, 203, 204. Thus, the position of the symmetry axis of the cylindrical object 110 can be determined from the surface 201, 202, 203, 204 having the highest edge contrast. For a more accurate determination of the position of the symmetry axis, each surface 201, 202, 203, 204 detected can preferably be divided into partial areas perpendicular to the suspected symmetry axis, and the light-dark contrast can be detected for each partial area. Then, the position of the symmetry axis can be generated by evaluating the partial area having the highest contrast among all areas 201, 202, 203, 204.

[0072] For example, the point 210 of the left partial area of the surface 203 can have the highest intensity. From this it can be concluded that the position of the symmetry axis in the object 110 and the orientation of this position are determined, and, in the case of known symmetry, in particular if a cylindrical object is present, the position of the entire object 110 is determined from this. Many further examples are conceivable.

[0073] The scanning of the volume layer by layer in transverse layers within the interior of the object 110 is only one possible exemplary embodiment. Other procedures, such as scanning in vertical planes or spiral scanning, are also conceivable. Furthermore, the scanning can also be made adaptive, for example, adjusting the scanning rate depending on the signal on the detector 115.

[0074] List of reference signs 10 device for determining the spatial position of a non-spherical object 50 light source 60 beam splitter 70 objective 75 galvanometer scanner 80 detector 100 light field 101 focal component of the light field 102 reflection component of the light field 103 focal point 104 phase wavefront 105 light field incident on the detector 110 object 111 surface portion 112 local surface normal 113 interior 114 inner boundary surface 115 center point 120 coordinate system 150 evaluation and supervision unit 151 connection 152 monitor 153 display screen 154 keyboard 201, 202, 203, 204 surface 210 point representing the corresponding focal point on the surface.

Claims

1. A method for determining the spatial position of a non-spherical object (110), the non-spherical object having at least one surface portion (111) of a known shape, the method comprising the steps of: a) At least two light fields (100) are radiated onto the object (110) through an objective lens (70), wherein each light field (100) has a known phase wavefront (104), wherein the phase wavefronts (104) of the at least two light fields (100) are different from each other at least after the objective lens (70), wherein the curvature of the phase wavefront (104) at the exit window of the objective lens (70) is less than the minimum curvature of the surface portion (111) of the object (110) in at least one spatial direction, wherein for at least one light field (100), there exists at least one line located in the surface portion (111), along which at least two local surface normals (112) of the surface portion (111) are orthogonal to the phase wavefront (104) of the at least one light field (100); b) Detecting the reflection components (102) of at least two of the light fields (100) originating from the object (110) using a detector (80); and c) Determine the spatial position of the non-spherical object (110) from the reflection components (102) of at least two detected light fields (100) based on the expected backscattering signal generated by the surface portion (111) of the known shape.

2. The method according to the preceding claim, wherein, The irradiation of at least two light fields (100) onto the object (110) through the objective lens (70) is carried out continuously over time.

3. The method according to any one of the preceding claims, wherein, At least two of the optical fields (100) are focused beam clusters or include focused beam clusters, wherein the focused beam clusters have a substantially spherical phase wavefront (104).

4. The method according to any one of the preceding claims, wherein, The at least two local surface normals (112) of the surface portion (111) are orthogonal to the phase wavefront (104) of the light field (100) currently applied to the surface portion (111), wherein the distance between the focal point (103) and the surface portion (111) corresponds to at least twice the diameter of the focal area.

5. The method according to any one of the preceding claims, wherein, The phase wavefronts (104) of at least two of the optical fields (100) are different from each other in the following way: - Modify at least one optical field in the optical field (100) in the beam path prior to the objective lens (70) by using a galvanometer scanner (75); or - By using a diffraction element to generate a change in at least one of the optical fields in the optical field (100); or - A relative displacement occurs between the objective lens (70) and the object (110) between at least two of the light fields (100).

6. The method according to any one of the preceding claims, wherein, The reflection components (102) of at least two of the light fields (100) originating from the object (110) are generated at the surface portion (111) of the known shape and / or at the inner boundary surface (114) of the interior (113) of the object (110).

7. The method according to any one of the preceding claims, wherein, The surface portion (111) of known shape includes the entire surface of the object (110), or wherein the distribution of the reflection components (102) of at least two of the light fields (100) on the entire surface of the object (110) is known, modeled or estimated.

8. The method according to any one of the preceding claims, wherein, The detection of the reflection components (102) of at least two light fields (100) originating from the object (110) by using a detector (80) is synchronized with the generation of a time-continuous light field (100).

9. The method according to any one of the preceding claims, wherein, The focused component (101) of the light field (100) is deflected perpendicular to the propagation direction of the light field (100) in two dimensions, and the reflected component (102) of the light field (100) originating from the object (110) is detected on at least two surfaces (201, 202, 203, 204) unfolded in the two dimensions, wherein the light occurs between the detection of the reflected component (102) of the light field (100) originating from the object (110) on two different surfaces (201, 202, 203, 204). The relative change in position of the focal point (103) of the field (100) relative to the object (110), wherein the spatial position of the object (110) is determined according to the following focal points (103) or groups of focal points (103), the intensity of the reflection component (102) of the light field (100) originating from the object (110) of the focal point (103) or groups of focal points (103) is higher than at least one intensity threshold, and the distance of the focal point (103) or groups of focal points (103) from the surface of the object (110) corresponds to at least twice the diameter of the focal area.

10. The method according to the preceding claim, wherein, In order to determine the intensity of the reflection component (102) originating from the object (110), an edge recognition method is used on the at least two surfaces (201, 202, 203, 204), wherein the edge recognition method is configured to determine the contrast between the focal point (103) or group of focal points (103) and the corresponding surrounding environment of the focal point (103) or group of focal points (103) on the relevant surfaces (201, 202, 203, 204).

11. A computer program for determining the spatial position of a non-spherical object (110), said non-spherical object having a surface portion (111) of a known shape, wherein, The computer program contains instructions that, when executed by a computer or computer network, cause the computer or computer network to perform at least step c) of the method for determining the spatial location of a non-spherical object (110) according to any of the preceding method claims, the non-spherical object (110) having at least one surface portion (111) of a known shape.

12. An apparatus for determining the spatial position of a non-spherical object (110), the non-spherical object having a surface portion (111) of a known shape, the apparatus comprising: - At least one light source (50) configured to generate at least two light fields (100), wherein each light field (100) has a known phase wavefront (104), wherein the phase wavefronts (104) of the at least two light fields (100) are different from each other at least after the objective lens (70), wherein the curvature of the phase wavefront (104) at the exit window of the objective lens (70) is less than the minimum curvature of the surface portion (111) of the object (110) in at least one spatial direction, wherein for at least one light field (100), there exists at least one line located in the surface portion (111), along which at least two local surface normals (112) of the surface portion (111) are orthogonal to the phase wavefront (104) of the at least one light field (100); - At least one objective lens (70), wherein at least one of the objective lenses (70) is configured to radiate at least two of the light fields (100) onto the object (110); - At least one detector (80), said at least one detector (80) being configured to detect the reflection components (102) of at least two of the light fields (100) originating from said object (110); and - At least one evaluation and supervision unit (150) is configured to determine the spatial position of the non-spherical object (110) based on the reflection components (102) of at least two of the light fields (100) based on the expected backscattering signal generated by the surface portion (111) of the known shape.

13. The apparatus according to the preceding claim, wherein, The light source (50) is a laser of a direct-write lithography system.

14. The apparatus according to any one of the preceding claims, wherein at least one of the objectives (70) is further configured to radiate at least one light field (105) onto the detector (80).

15. The apparatus according to any one of the preceding device claims, the apparatus further comprising at least one galvanometer scanner (75) configured to modify at least one light field in the light field (100) in a beam path prior to the objective lens (70).

16. The apparatus according to any one of the preceding claims, further comprising at least one element configured to displace the object (110) and / or the objective lens (70), the at least one element preferably selected from a positioning stage or a sensing element.

17. The apparatus according to any one of the preceding claims, further comprising at least one diffraction element configured to cause a change in the at least one optical field in the optical field (100), wherein, Preferably, the diffraction element is a digital light modulation element, and in particular, the digital light modulation element is selected from a spatial light modulator or a digital micromirror unit.

Images