KR-102963278-B1 - A method and system for determining the position of an object relative to an assembly as well as the position of an element of an optical system in an assembly for processing or measuring an object by parallel interference measurements.

KR102963278B1KR 102963278 B1KR102963278 B1KR 102963278B1KR-102963278-B1

Abstract

Methods and systems are described for determining the relative position of an element of an optical system of an assembly for processing or measuring an object along a predetermined measurement line associated with the optical system, and for determining the separation distance between a processing tool or measuring instrument and an object outside the processing tool or measuring instrument. These involve the generation of a reference beam and a measurement beam of low coherence optical radiation, wherein the measurement beam and the reference beam comprise, alternately or in combination, a main beam and a multiplexed additional beam. A measurement beam guided toward an element of the optical system or toward an object and reflected back therefrom is superimposed on the reference beam in the common incident zone of an interferometric optical sensor arrangement. The position or frequency of the main interference fringe pattern and the additional interference fringe pattern is detected in the common incident zone, and as a function thereof, (a) the position of an element of the optical system, or the separation distance between a processing tool or measuring instrument and an object outside the processing tool or measuring instrument, and (b) the difference between each, a predetermined nominal position or nominal separation distance are determined.

Inventors

도나델로, 시몬
프레비탈리, 바바라
콜롬보, 다니엘

Assignees

아디제 에스.피.에이.

Dates

Publication Date: 20260508
Application Date: 20201204
Priority Date: 20191206

Claims (20)

A method for determining the relative position of an element of an optical system of an assembly for processing or measuring an object along a predetermined measurement line associated with an optical system, - generating a measurement beam, wherein the measurement beam is low coherence optical radiation, propagating the measurement beam toward the element along the measurement line, and propagating the measurement beam reflected or scattered by the back-reflective surface of the element toward the optical interferometer sensor means, wherein the measurement beam collides with at least partial back-reflection — the measurement beam travels along a measurement optical path from individual sources to the optical interferometer sensor means, wherein the measurement optical path comprises a first section between the source and the back-reflective surface of the element and a second section between the back-reflective surface of the element and the interferometer sensor means, wherein the first section and the second section have individual predetermined nominal geometric lengths when the element is in a predetermined nominal position corresponding to a predetermined operating condition of the system —; - A step of generating individual reference beams of the low coherence optical radiation and propagating the reference beams toward the optical interferometer sensor means ― The reference beams comprise a main reference beam resulting from the movement of a main reference optical path having an optical length equivalent to the optical length of the measurement optical path under a nominal operating condition in which the position of the element is a predetermined nominal position, and at least one additional multiplexed reference beam resulting from the movement of an additional reference optical path having a geometric length different from the geometric length of the main reference optical path under an operating condition in which the position of the element is a predetermined modified position ―; - A step of superimposing the measurement beam and the reference beam on at least a common incident zone of the optical interferometer sensor means along a predetermined illumination axis; - A step of detecting the position of the main pattern of interference fringes between the measurement beam and the main reference beam along the illumination axis in the common incident zone ―the extension of the pattern of interference fringes along the illumination axis corresponds to the coherence length of the additional pattern of interference fringes between the measurement beam and the additional reference beam of the low coherence optical radiation, and the additional pattern of interference fringes has (i) a peak or maximum of the intensity of the envelope of the optical radiation that is different from the peak or maximum of the intensity of the envelope of the main pattern of interference fringes, or (ii) an intrinsic position of the intensity envelope of the optical radiation that is offset from the intrinsic position of the intensity envelope of the optical radiation of the main pattern of interference fringes, or (iii) a spatial frequency that is different from the spatial frequency of the main pattern of interference fringes—; or - A step of detecting the frequency of a pattern of fringes in a wavelength spectrum obtained from the wavelength dispersion of the measurement beam and the main reference beam from the main interference between the measurement beam and the main reference beam in the common incident region—the extension of said pattern in the frequency domain is determined by the coherence length of the low coherence optical radiation and by an additional pattern of interference fringes between the measurement beam and the additional reference beam, which is determined by (i) having a frequency different from the frequency of the main pattern of said interference fringes, or (ii) by the overlap of the measurement beam and the additional reference beam in a region of the common incident region that is different from the zone of overlap of the measurement beam and the main reference beam—; and - A step of determining the difference in optical length between the measurement optical path and the reference optical path or the additional reference optical path, wherein, respectively, as a function of the position of the pattern of interference fringes or the additional pattern of interference fringes along the illumination axis of the common incident zone, or as a function of the frequency of the pattern of interference fringes or the additional pattern of interference fringes in the frequency domain, (a) the current position of the element and (b) the difference between the predetermined nominal position of the element or the predetermined modified position along the axis of the measurement beam, respectively. A method characterized by including
A method for determining the separation distance between a processing tool or measuring device and at least a partially reflective surface of an object, along a predetermined measuring line associated with at least a proximal part of the processing tool or measuring device, for each surface of an object outside the processing tool or measuring device, said - A step of generating a measurement beam, wherein the measurement beam is low coherence optical radiation, propagating the measurement beam toward the surface of the object through the proximal part of the tool or device, and propagating the measurement beam reflected or scattered from the surface of the object toward an optical interferometer sensor means through the proximal part of the tool or device ― The measurement beam travels along a measurement optical path from individual sources to the optical interferometer sensor means, wherein the measurement optical path comprises a first section between the source and the proximal part of the tool or device and a second section between the proximal part of the tool or device and the interferometer sensor means, wherein the first section and the second section have individual predetermined and invariant geometric lengths ―; - A step of generating individual reference beams of the low coherence optical radiation and propagating the reference beams toward the optical interferometer sensor means ―the reference beams comprise a main reference beam resulting from the movement of a main reference optical path having an optical length equivalent to the optical length of the measurement optical path under a nominal operating condition corresponding to a predetermined nominal separation distance between the proximal part of the tool or device and the surface of the object, and at least one additional multiplexed reference beam resulting from the movement of an additional reference optical path having a geometric length different from the geometric length of the main reference optical path under an operating condition corresponding to a predetermined modified separation distance between the proximal part of the tool or device and the surface of the object. - A step of superimposing the measurement beam and the reference beam on at least a common incident zone of the optical interferometer sensor means along a predetermined illumination axis; - A step of detecting the position of the main pattern of interference fringes between the measurement beam and the main reference beam along the illumination axis in the common incident zone ―the extension of the pattern of interference fringes along the illumination axis corresponds to the coherence length of the additional pattern of interference fringes between the measurement beam and the additional reference beam of the low coherence optical radiation, and the additional pattern of interference fringes has (i) a peak or maximum of the intensity of the envelope of the optical radiation that is different from the peak or maximum of the intensity of the envelope of the optical radiation of the main pattern of interference fringes, or (ii) an intrinsic position of the intensity envelope of the optical radiation that is offset from the intrinsic position of the intensity envelope of the optical radiation of the main pattern of interference fringes, or (iii) a spatial frequency that is different from the spatial frequency of the main pattern of interference fringes—; or - A step of detecting the frequency of a pattern of fringes in a wavelength spectrum obtained from the wavelength dispersion of the measurement beam and the main reference beam from the main interference between the measurement beam and the main reference beam in the common incident region—the extension of said pattern in the frequency domain is determined by the coherence length of the low coherence optical radiation and by (i) having a frequency different from the frequency of the main pattern of said interference fringes, or (ii) determined by the coherence length of an additional pattern of interference fringes between the measurement beam and the additional reference beam, which is determined by the overlap of the measurement beam and the additional reference beam in a region of the common incident region that is different from the zone of overlap of the measurement beam and the main reference beam—; and - A step of determining the difference in optical length between the measurement optical path and the reference optical path or the additional reference optical path, wherein, respectively, as a function of the position of the pattern of interference fringes or the additional pattern of interference fringes along the illumination axis of the common incident zone, or as a function of the frequency of the pattern of interference fringes or the additional pattern of interference fringes in the frequency domain, (a) the current separation distance between the proximal part of the tool or device and the surface of the object, and (b) respectively, the difference between the predetermined nominal separation distance or the predetermined modified separation distance. A method characterized by including
In Article 1 or Article 2, A method in which the main reference optical path and the additional reference optical path overlap for at least a portion and collide co-linearly on the common incident zone of the optical interferometer sensor means.
In Paragraph 3, A method in which the additional reference optical path comprises at least partial back reflection on the surface of an optical element interposed along the optical path of the main reference beam.
In Paragraph 3, A method in which the additional reference optical path comprises at least a back reflection within an optical element interposed along the optical path of the main reference beam.
In Paragraph 3, A method in which the additional reference optical path comprises a path section deflected with respect to the optical path of the main reference beam.
In Article 6, A method in which the above-mentioned biased path section is obtained by interposing an optical element for partially extracting the reference beam from the optical path of the main reference beam and an optical element for reintroducing the extracted reference beam into the beam in the optical path of the main reference beam.
In Article 7, A method in which the optical element for beam portion extraction is a beam splitting optical device.
In Article 7, A method in which the optical element for beam portion extraction is a prism configured to continuously control the optical length of the section of the deflected path.
In Article 1 or Article 2, A method in which the main reference optical path and the additional reference optical path collide on individual different regions of the common incident zone of the optical interferometer sensor means.
In Article 1 or Article 2, The above optical interferometer sensor means comprises an arrangement of photodetectors along the illumination axis, and the arrangement of photodetectors is a linear arrangement of photodetectors.
In Article 1 or Article 2, The above optical interferometer sensor means comprises an arrangement of photodetectors along the illumination axis, and the arrangement of photodetectors is a two-dimensional arrangement of photodetectors.
A method for determining the relative position of an element of an optical system of an assembly for processing or measuring an object along a predetermined measurement line associated with an optical system, - A step of generating a measurement beam, wherein the measurement beam is low coherence optical radiation, propagating the measurement beam toward the element along the measurement line, and propagating the measurement beam reflected or scattered by the back-reflective surface of the element toward the optical interferometer sensor means, wherein the measurement beam collides with at least partial back-reflection ― The measurement beam travels along a measurement optical path from individual sources to the optical interferometer sensor means, wherein the measurement optical path comprises a first section between the source and the back-reflective surface of the element and a second section between the back-reflective surface of the element and the interferometer sensor means, wherein the first section and the second section have individual predetermined nominal geometric lengths when the element is in a predetermined nominal position corresponding to a predetermined operating condition of the system, and the measurement beam comprises a main measurement beam resulting from the movement of the main measurement optical path having transmission through each optical element interposed upstream of the element along the measurement line, and a geometric length different from the geometric length of the main measurement optical path Includes an additional multiplexed measurement beam resulting from the movement of an additional measurement optical path—; - A step of generating individual reference beams of the above-mentioned low-coherence optical radiation and propagating the reference beams toward the optical interferometer sensor means ― Under nominal operating conditions where the position of the element is a predetermined nominal position, the reference beams travel along a reference optical path having an optical length equivalent to the optical length of the main measurement optical path ―; - A step of superimposing the measurement beam and the reference beam on at least one common incident zone of the optical interferometer sensor means along a predetermined illumination axis; - A step of detecting the position of the main pattern of interference fringes between the main measurement beam and the reference beam along the illumination axis in the common incidence zone ―the extension of the pattern of interference fringes along the illumination axis corresponds to the coherence length of the low coherence optical radiation and the additional pattern of interference fringes between the additional measurement beam and the reference beam, and the additional pattern of interference fringes has (i) a peak or maximum of the intensity of the envelope of the optical radiation that is different from the peak or maximum of the intensity of the envelope of the optical radiation of the main pattern of interference fringes, or (ii) an intrinsic position of the intensity envelope of the optical radiation that is offset from the intrinsic position of the intensity envelope of the optical radiation of the main pattern of interference fringes, or (iii) a spatial frequency that is different from the spatial frequency of the main pattern of interference fringes—; or - A step of detecting the frequency of a pattern of fringes in a wavelength spectrum obtained from the wavelength dispersion of the main measurement beam and the reference beam from the main interference between the main measurement beam and the reference beam in the common incidence zone above—the extension of said pattern in the frequency domain is determined by the coherence length of the low coherence optical radiation and by (i) having a frequency different from the frequency of the main pattern of said interference fringes, or (ii) determined by the coherence length of an additional pattern of interference fringes between the additional measurement beam and the reference beam, which is determined by the overlap of the additional measurement beam and the reference beam in the region of the common incidence zone above that is different from the zone of overlap of the main measurement beam and the reference beam—; and - A step of determining the difference in optical length between the measurement optical path or the additional reference optical path and the reference optical path, wherein the difference indicates the difference between (a) the current position of the element and (b) the predetermined nominal position of the element along the axis of the measurement beam, respectively, as a function of the position of the pattern of the interference fringes or the additional pattern of the interference fringes along the illumination axis of the common incident zone, or as a function of the frequency of the pattern of the interference fringes or the additional pattern of the interference fringes in the frequency domain. A method characterized by including
A method for determining the separation distance between a processing tool or measuring device and at least a partially reflective surface of an object, along a predetermined measuring line associated with at least a proximal part of the processing tool or measuring device, for each surface of an object outside the processing tool or measuring device, said - A step of generating a measurement beam, wherein the measurement beam is low coherence optical radiation, propagating the measurement beam toward the surface of the object through the proximal part of the tool or device, and propagating the measurement beam reflected or scattered from the surface of the object toward an optical interferometer sensor means through the proximal part of the tool or device ― The measurement beam travels along a measurement optical path from individual sources to the optical interferometer sensor means, wherein the measurement optical path comprises a first section between the source and the proximal part of the tool or device and a second section between the proximal part of the tool or device and the interferometer sensor means, wherein the first section and the second section have individual predetermined and invariant geometric lengths, and the measurement beam comprises a main measurement beam resulting from the movement of a main measurement optical path having transmission through each optical element interposed upstream of the tool or device along the measurement line, and an additional multiplexed measurement beam resulting from the movement of an additional measurement optical path having a geometric length different from the geometric length of the main measurement optical path. Including—; - A step of generating individual reference beams of the above-mentioned low-coherence optical radiation and propagating the reference beams toward the optical interferometer sensor means ― Under nominal operating conditions where the distance between the proximal part of the tool or device and the surface of the object corresponds to a predetermined nominal separation distance, the reference beams travel along a reference optical path having an optical length equivalent to the optical length of the main measurement optical path ―; - A step of superimposing the measurement beam and the reference beam on at least one common incident zone of the optical interferometer sensor means along a predetermined illumination axis; - A step of detecting the position of the main pattern of interference fringes between the main measurement beam and the reference beam along the illumination axis in the common incidence zone ―the extension of the pattern of interference fringes along the illumination axis corresponds to the coherence length of the low coherence optical radiation and the additional pattern of interference fringes between the additional measurement beam and the reference beam, and the additional pattern of interference fringes has (i) a peak or maximum of the intensity of the envelope of the optical radiation that is different from the peak or maximum of the intensity of the envelope of the optical radiation of the main pattern of interference fringes, or (ii) an intrinsic position of the intensity envelope of the optical radiation that is offset from the intrinsic position of the intensity envelope of the optical radiation of the main pattern of interference fringes, or (iii) a spatial frequency that is different from the spatial frequency of the main pattern of interference fringes—; or - A step of detecting the frequency of a pattern of fringes in a wavelength spectrum obtained from the wavelength dispersion of the main measurement beam and the reference beam from the main interference between the main measurement beam and the reference beam in the common incidence zone above—the extension of said pattern in the frequency domain is determined by the coherence length of the low coherence optical radiation and by (i) having a frequency different from the frequency of the main pattern of said interference fringes, or (ii) determined by the coherence length of an additional pattern of interference fringes between the additional measurement beam and the reference beam, which is determined by the overlap of the additional measurement beam and the reference beam in the region of the common incidence zone above that is different from the zone of overlap of the main measurement beam and the reference beam—; and - Each, as a function of the position of the pattern of interference fringes or the additional pattern of interference fringes along the illumination axis of the common incident zone, or as a function of the frequency of the pattern of interference fringes or the additional pattern of interference fringes in the frequency domain, a step of determining the difference in optical length between the measurement optical path or the additional measurement optical path and the reference optical path, indicating the difference between (a) the current separation distance between the proximal part of the tool or device and the surface of the object, and (b) the predetermined nominal separation distance. A method characterized by including
In Article 13 or Article 14, A method in which the main measurement optical path and the additional measurement optical path overlap for at least a portion and collide collinearly on the common incident zone of the optical interferometer sensor means.
In Article 15, A method in which the additional measurement optical path comprises at least partial back reflection from the surface of an optical element interposed along the optical path of the main measurement beam.
In Article 15, A method in which the additional measurement optical path comprises at least a back reflection within an optical element interposed along the optical path of the main measurement beam.
In Article 15, A method in which the additional measurement optical path comprises a path section deflected from the optical path of the main measurement beam.
In Article 18, A method in which the above-mentioned biased path section is obtained by interposing an optical element for partially extracting the measurement beam from the optical path of the main measurement beam and an optical element for reintroducing the extracted measurement beam into the beam in the optical path of the main measurement beam.
In Article 19, A method in which the optical element for beam portion extraction is a beam splitting optical device.

Description

A method and system for determining the position of an object relative to an assembly as well as the position of an element of an optical system in an assembly for processing or measuring an object by parallel interference measurements. The present invention generally deals with industrial processing or measurement methods for objects or materials, performed by, for example, a tool, device, or probe arranged at a predetermined separation distance or in contact with an object or said material, for example, during the control of laser processing of a material for laser cutting, drilling, or welding of the material or for additive manufacturing of said materials, said materials. In particular, the present invention deals with determining the relative position of an element of an optical system or a surface that is at least partially reflective outside the optical system in relation to a corresponding predetermined reference of a processing or measuring assembly. An element of the optical system is an element positioned along the propagation direction of a laser beam of a processing assembly, such as the head of a laser processing machine, or along the propagation direction of optical measurement radiation in a measuring assembly of a machine tool. Its relative position is determined by comparison with a predetermined reference element, such as an end of a processing tool or measuring instrument or a radiation source. A surface that is at least partially reflective outside the optical system of the processing or measuring assembly is, for example, the surface of an object undergoing processing or measurement, and its relative position is determined by comparison with a predetermined reference element, such as an end of a processing tool or measuring instrument facing the object under operating conditions or an optical radiation source for processing or measurement. Furthermore, the present invention relates to performing parallel measurements of the positions of a plurality of elements of an optical system or the positions of a plurality of reflective surfaces outside the system, or also to performing parallel measurements of the positions of an element of an optical system and a reflective surface outside the system. More specifically, the present invention relates to a method for determining the relative position of an element of an optical system of an assembly for processing or measuring an object along a predetermined measurement line associated with an optical system, as specified in the preamble of claims 1 and 13. According to an additional aspect, the present invention relates to a machine for laser processing of a material according to the preamble of claim 24. The present invention also relates to a method for determining a separation distance between a processing tool or measuring instrument and at least a partially reflective surface of an object, along a predetermined measuring line associated with at least a proximal part of the processing tool or measuring instrument, with respect to the surface of an object outside the processing tool or measuring instrument, as specified in the preamble of claims 2 and 14. According to an additional aspect, the present invention relates to a machine for laser processing of a material according to the preamble of claim 25. According to another aspect, the present invention relates to a method for determining the positions of a plurality of elements that are at least partially reflective to optical radiation in a system comprising a plurality of optical components of an assembly for processing or measurement, as specified in the preamble of claim 23, or comprising at least one optical element of an assembly for processing or measurement and one object outside the assembly that undergoes said processing or measurement, wherein the plurality of at least partially reflective elements are arranged along a predetermined common measurement line. In the following specifications and claims, the term “object” refers to the finished product or workpiece being processed. When applied to machine tools, particularly machines for laser processing, the term “workpiece,” and in a preferred embodiment, “metal workpiece,” is used to identify any given manufactured article, elongated profile or sheet having a closed or flat section, such as a hollow circular, rectangular, or square cross section, or an open cross section, such as an L, C, U, or other shaped section. In additive manufacturing, the terms “material” or “precursor material” identify a raw material, generally a powder, that undergoes sintering or localized melting by a laser beam. In the following specifications and claims, the term “material,” and in a preferred embodiment, “metallic material,” is used to identify any given manufactured article, elongated profile or sheet having a closed or flat section, such as a hollow circular, rectangular, or square cross section, or an open cross section, such as an L, C, U, or o