WO2024133386A1 - Dispositif de mesure confocal chromatique - Google Patents

Dispositif de mesure confocal chromatique Download PDF

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Publication number
WO2024133386A1
WO2024133386A1 PCT/EP2023/086833 EP2023086833W WO2024133386A1 WO 2024133386 A1 WO2024133386 A1 WO 2024133386A1 EP 2023086833 W EP2023086833 W EP 2023086833W WO 2024133386 A1 WO2024133386 A1 WO 2024133386A1
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WO
WIPO (PCT)
Prior art keywords
light
measuring device
connecting piece
imaging optics
detector
Prior art date
Application number
PCT/EP2023/086833
Other languages
German (de)
English (en)
Inventor
Christoph Dietz
Andreas KRIEGER
Stephan Weiss
Frauke Roellinghoff
Original Assignee
Precitec Optronik Gmbh
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Publication date
Application filed by Precitec Optronik Gmbh filed Critical Precitec Optronik Gmbh
Publication of WO2024133386A1 publication Critical patent/WO2024133386A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0608—Height gauges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes
    • G02B21/0004—Microscopes specially adapted for specific applications
    • G02B21/002—Scanning microscopes
    • G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
    • G02B21/0032—Optical details of illumination, e.g. light-sources, pinholes, beam splitters, slits, fibers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B21/00—Microscopes
    • G02B21/0004—Microscopes specially adapted for specific applications
    • G02B21/002—Scanning microscopes
    • G02B21/0024—Confocal scanning microscopes (CSOMs) or confocal "macroscopes"; Accessories which are not restricted to use with CSOMs, e.g. sample holders
    • G02B21/0052—Optical details of the image generation
    • G02B21/0064—Optical details of the image generation multi-spectral or wavelength-selective arrangements, e.g. wavelength fan-out, chromatic profiling
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B2210/00—Aspects not specifically covered by any group under G01B, e.g. of wheel alignment, caliper-like sensors
    • G01B2210/50—Using chromatic effects to achieve wavelength-dependent depth resolution

Definitions

  • the invention relates to a chromatic confocal measuring device.
  • Chromatic confocal measuring devices are used, for example, to measure objects.
  • a surface of an object can be measured, which can be used to assess a height or an unevenness.
  • the object can be flat or even.
  • the invention relates to a chromatic confocal measuring device.
  • the measuring device has a light source which emits light of several different wavelengths and/or with a continuous spectrum of wavelengths.
  • the measuring device has a first confocal aperture through which light from the light source passes.
  • the measuring device has a second confocal aperture.
  • the measuring device has a splitting optical element with a first part and a second part.
  • the first part and the second part are each designed as a prism or grating.
  • the splitting optical element has a connecting piece, wherein the first part and the second part are firmly connected to one another by means of the connecting piece.
  • the measuring device has an illumination imaging optics.
  • the illumination imaging optics has the first part of the splitting optical element.
  • the illumination imaging optics has a first lens system with at least one first lens, which is separated from the first part of the splitting optical element is spatially separated, wherein the first lens system receives light from the first part of the splitting optical element and the effective focal length of the first lens system differs for different wavelengths.
  • the illumination imaging optics are designed such that focus points of different wavelengths are formed at different locations for at least one point of passage of the light through the first confocal aperture, wherein the locations lie along a line segment which forms an acute angle to the center axis of the first lens system.
  • the measuring device is designed to measure an object which intersects the line segment and reflects at least part of the light.
  • the first confocal aperture has several points through which light passes, for example through a slit-shaped opening of the first confocal aperture, which can be viewed as a series of an infinite number of immediately adjacent points, for each point through which light passes, focus points of different wavelengths are formed along a corresponding line segment.
  • the large number of immediately adjacent line segments of focus points form a surface segment.
  • the focus points of the same wavelength but different points through which light passes through the aperture form focus lines on the surface segment transverse to the line segments.
  • Such an embodiment can in particular be referred to as a line sensor.
  • a line sensor is characterized in particular by the fact that the first confocal aperture has a slit-shaped opening and/or a large number of points through which light passes through the first confocal aperture are provided. Such embodiments are fundamentally possible with the measuring device described here.
  • the measuring device has a detection imaging optics.
  • the detection imaging optics comprise the second part of the splitting optical element.
  • the detection imaging optics are designed to receive light reflected from the object exclusively from directions that differ from the directions from which the illumination light falls on the object.
  • the detection imaging optics are designed to image the focal points of all wavelengths onto the second confocal aperture.
  • the detection imaging optics have a second lens system with at least one second lens, which is preferably spatially separated from the second part of the splitting optical element.
  • the second lens system can in particular receive light reflected from the object and the effective focal length of the second lens system can differ for different wavelengths.
  • the chromatic confocal measuring device further comprises a detector which is configured to detect an intensity of the light passing through the second confocal aperture.
  • Such a measuring device creates a possibility of measuring an object in an advantageous manner.
  • splitting optical elements of the illumination imaging optics and the detection imaging optics can lead to a falsification of the measurement result even with a slight relative misalignment relative to one another.
  • a splitting optical element which firmly connects its first part and its second part to one another by means of a connecting piece, it is impossible due to the design for such misalignments to occur during operation or after an adjustment.
  • the connecting piece creates a fixed connection between components of the illumination imaging optics and the detection imaging optics, whereby the two imaging optics are firmly connected to one another, which ensures a consistent alignment of the parts of the splitting optical element relative to one another.
  • the splitting optical element is an element that ensures that a wavelength-dependent splitting is possible in both the illumination imaging optics and the detection imaging optics.
  • a light beam which typically combines several wavelengths, is split by deflecting the light depending on the wavelength, whereby, as already mentioned, in interaction with the first lens system, focus points of different wavelengths are formed at different locations for a point of passage of the light through the first confocal aperture.
  • detection-imaging optics a corresponding splitting effect would be achieved if an inverse beam path compared to the beam path relevant here were used. Such a beam path could, for example, run from the detector back to the light source.
  • the second part of the splitting optical element typically has the function of reversing the wavelength-dependent deflection for precisely those rays and wavelengths whose focal point coincides with a reflective surface of the object being measured.
  • Each focal point that lies on such a reflective surface is therefore imaged again onto a fixed point on the second confocal aperture.
  • all focal points on the object that correspond to a point of passage through the first confocal aperture are imaged again onto a common point on the second confocal aperture.
  • the wavelength-dependent splitting is amplified by the second part of the splitting optical element.
  • the connecting piece connects the first part and the second part, in particular directly, to one another.
  • the connecting piece is not part of a housing of the chromatic confocal measuring device, but rather is an element that connects the first part and the second part directly to one another. If, for example, two parts with splitting functionality are each mounted on a holder and each holder is connected to a housing, the holders and the housing are not considered to be a connecting piece. Rather, the connecting piece is part of the optical components of the measuring device, with the splitting optical element being provided in particular in such a way that it has an optical effect in both the illumination imaging optics and the detection imaging optics.
  • the connecting piece connects the first part and the second part to one another in such a way that it is not possible to change the alignment and position of the first part and the second part relative to one another without breaking the material-bonded connections.
  • the first part of the splitting optical element is part of the illumination imaging optics and is illuminated by the light from the light source. In this first part, splitting then takes place depending on the different wavelengths. The wavelength dependence of the first lens system then ensures that the focus points of different wavelengths are formed at different locations. The locations are in particular along the line segment already mentioned, whereby the line segment is typically formed along a straight line.
  • the line segment can, for example, be aligned transversely to a surface of the object and/or perpendicular to the earth's surface, the latter for example if the measuring device is aligned so that the line segment is aligned perpendicular to the earth's surface.
  • the measuring device is aligned so that the line segment is aligned perpendicular to the earth's surface.
  • other angles to the surface of the object and/or to the earth's surface are also possible. Slight deviations of the focus points from the line segment, which are based for example on unavoidable tolerances, are not considered to be a deviation from the embodiment claimed herein.
  • Focusing on the second confocal aperture can be understood in particular as focusing on a slit or an opening of the second confocal aperture.
  • the detector can in particular detect and evaluate the light that has passed through such a slit or such an opening in the second confocal aperture, in particular after it has passed through the illumination imaging optics, been reflected by the object and then passed through the detection imaging optics.
  • the detector in particular enables a measurement that allows an evaluation that provides conclusions about the surface or other properties of the object.
  • the connecting piece can be made of a different glass or a different material than the first part and the second part. This allows a material separation between the first part, the second part and the connecting piece.
  • a material can be used for the connecting piece which does not meet special requirements which are placed on the first part and the second part for optical reasons.
  • the Connecting piece may have a lower refractive index and/or a different Abbe number. This allows in particular to use a cheaper material for the connecting piece than for the first part and the second part.
  • the connecting piece may in particular be made of glass. However, it may be made of another material such as plastic.
  • the first part and the second part can in particular be made of a glass or material with a higher refractive index and/or lower Abbe number (and thus more pronounced dispersion) than the connecting piece.
  • the high refractive index advantageously enables the already described functionality of splitting depending on the wavelength or merging. Such functionality is not required for the connecting piece. Accordingly, a glass or other material with a lower refractive index and/or a higher Abbe number can be used for the connecting piece, which is typically cheaper and/or easier to process.
  • a transparent plastic can also be used instead of glass.
  • the connecting piece can be made of the same glass or the same material as the first part and/or the second part. This enables, for example, simple manufacture and a design without material transitions.
  • the connecting piece can be designed in the form of a plate. This allows for a simple design of the connecting piece, easy handling and easy connection of the two parts.
  • the connecting piece, the first part and the second part can be connected to one another in a material-locking manner. This results in a particularly strong and unchangeable connection. This means that the relationships in terms of position and alignment between the first part and the second part relative to one another are firmly defined. It is possible for the connecting piece to have the same height as the first part and/or the second part when viewed along a propagation direction of the light. This enables a simple and compact design.
  • the propagation direction relevant here can, for example, be the one that the light has immediately after the light source or immediately after passing through the first confocal aperture. The height can be determined along such a propagation direction.
  • the connecting piece, the first part and the second part can be designed as a continuous element without material transitions and/or made from one piece. This also enables a particularly strong design, whereby the production of material-locking connections can be dispensed with. There are also no other options for changing the relative position and orientation of the first part and the second part relative to each other. This ensures a particularly high level of safety in terms of optical functionality.
  • the connecting piece, the first part and the second part are manufactured separately from one another and/or have been connected to one another. This enables separate manufacture, for example using different materials. The parts and the connecting piece can then be connected to one another to achieve the desired strength.
  • the first part and the second part can, for example, be prisms which are arranged resting on the connecting piece or hanging from the connecting piece. This allows prisms to be easily connected to the connecting piece.
  • the connecting piece can be plate-shaped, which allows easy geometric connection with prisms.
  • the connecting piece can define a non-changeable positional relationship and a non-changeable orientation of the first part and the second part relative to each other.
  • This can mean in particular that there are no adjustable elements such as screws or clamps which allow a variation in the location and/or orientation of the first part and the second part relative to to each other.
  • the connection is preferably made by permanent bonding. This allows a particularly high level of reliability to be achieved.
  • the connecting piece can be arranged exclusively outside the beam paths of the illumination imaging optics and the detection imaging optics. Nevertheless, the connecting piece is part of the splitting optical element and not part of a higher-level supporting structure or housing.
  • the connecting piece is also arranged in the beam path of the illumination imaging optics and/or the detection imaging optics. This makes it possible in particular for the connecting piece to also take on an optical function and/or for a simple flat connection between the first part and/or second part and the connecting piece to be possible. This can be done, for example, as explained below.
  • the connecting piece forms a prism together with the first part. This can be at least partially delimited from the rest of the connecting piece by an imaginary line.
  • the connecting piece forms a prism together with the second part. This can be at least partially delimited from the rest of the connecting piece by an imaginary line.
  • a functionality such as that of a prism can be available without restriction in the beam path, although a delimitation from the connecting piece may only be possible via an imaginary line as already mentioned.
  • the imaginary line can be designed in such a way that when the imaginary line is taken into account, a typical shape of a prism is created.
  • the imaginary line does not necessarily have to be visible in the splitting optical element; rather, it can serve purely as mental support when identifying an element such as a prism.
  • the connecting piece can have a continuous flat outer surface on a side facing the object or on a side facing away from the object. This enables a simple design, whereby the flat outer surface also prevents this outer surface from leading to an undesirable deflection of the respective light beam.
  • a first contact surface of the connecting piece that contacts the first part can in particular be aligned obliquely to the outer surface of the connecting piece that faces away from the first part and the second part.
  • a second contact surface of the connecting piece that contacts the second part can in particular be aligned obliquely to the outer surface of the connecting piece that faces away from the first part and the second part.
  • a first contact surface of the connecting piece that contacts the first part can be aligned in particular parallel to the outer surface of the connecting piece that faces away from the first part and the second part.
  • a second contact surface of the connecting piece that contacts the second part can be aligned in particular parallel to the outer surface of the connecting piece that faces away from the first part and the second part.
  • the measuring device has a carrier element.
  • the connecting piece can in particular be fastened to the carrier element.
  • the carrier element can in particular be connected to a housing of the measuring device opposite to the connecting piece.
  • it can be connected to a supporting structure of the measuring device.
  • Other optical components or all other optical components can also be fastened to such a supporting structure.
  • the described embodiment makes it possible for the connecting piece to be held by the carrier element and in particular the connection between the connecting piece and the housing or other supporting structure mediated by the carrier element defines the position of the connecting piece and thus also of the splitting optical element within the measuring device.
  • a supporting structure can be designed as a base plate, for example.
  • all or at least some or most of the optical components can be fastened to it.
  • the connecting piece can be detachably attached to the The carrier element can be fastened, in particular by releasing only a force-fitting and/or a form-fitting connection, but in particular not a material-fitting connection.
  • first part and the second part are not themselves attached to the carrier element and/or are only attached to the carrier element by means of the connecting piece.
  • the connecting piece defines the position and orientation of the first part and the second part.
  • the first part and the second part are attached exclusively to the connecting piece.
  • the connecting piece thus represents the only connection of the splitting optical element to a carrier plate, a housing or another supporting structure.
  • the connecting piece has an intermediate surface between the contact surfaces, which is designed parallel to the outer surface of the connecting piece facing away from the first part and the second part.
  • the intermediate surface can in particular transition seamlessly into the first contact surface and/or the second contact surface. This enables simple production of the connecting piece and simple formation of the splitting optical element.
  • the chromatic confocal measuring device has a light source which emits light of several different wavelengths and/or with a continuous spectrum of wavelengths.
  • the measuring device has a first confocal aperture through which light from the light source passes. It also has a second confocal aperture.
  • the measuring device has an illumination imaging optics.
  • the illumination imaging optics have a first splitting optical element, which is designed as a prism or grating.
  • the illumination imaging optics have a first lens system with at least one first lens, which is spatially separated from the first splitting optical element.
  • the first lens system receives light from the first splitting optical element.
  • the effective focal length of the first lens system differs for different wavelengths.
  • the illumination imaging optics are designed such that focus points of different wavelengths are formed at different locations for at least one point of passage of the light through the first confocal aperture, the locations lying along a line segment that forms an acute angle to the center axis of the first lens system.
  • the measuring device is set up to measure an object that intersects the line segment and reflects at least part of the light.
  • the first confocal aperture has several points through which light passes, for example through a slit-shaped opening of the first confocal aperture, which can be viewed as a series of an infinite number of immediately adjacent points, for each point through which light passes, focus points of different wavelengths are formed along a corresponding line segment.
  • the large number of immediately adjacent line segments of focus points form a surface segment.
  • the focus points of the same wavelength but different points through which light passes through the aperture form focus lines on the surface segment transverse to the line segments.
  • Such an embodiment can in particular be referred to as a line sensor.
  • a line sensor is characterized in particular by the fact that the first confocal aperture has a slit-shaped opening and/or a large number of points through which light passes through the first confocal aperture are provided. Such embodiments are fundamentally possible with the measuring device described here.
  • the measuring device has a detection imaging optics.
  • the detection imaging optics are designed to receive light reflected from the object exclusively from directions that differ from the directions from which the illumination light falls on the object.
  • the detection Imaging optics are designed to image the focus points of all wavelengths onto the second confocal aperture.
  • the detection imaging optics have a second lens system with at least one second lens, which is preferably spatially separated from the second part of the splitting optical element or from the second splitting optical element.
  • the second lens system can in particular receive light reflected from the object and the effective focal length of the second lens system can differ for different wavelengths.
  • the measuring device has a detector which is configured to detect an intensity of the light passing through the second confocal aperture.
  • the second confocal aperture has a slot through which light passes to the detector h. Furthermore, in this embodiment, the second confocal aperture is expediently completely or partially mirrored laterally to this slot on a side facing the detection imaging optics, so that incident light is at least partially reflected back into the detection imaging optics.
  • the first confocal aperture has a slot through which light from the light source passes, and also has a control opening which is arranged next to the slot.
  • the second confocal aperture is expediently mirrored at least in such a way that light emerging from the control opening in the direction of the illumination imaging optics is reflected back onto the control opening. This makes it possible to couple light into the beam path through the control opening, which is reflected back onto the control opening and can also be measured there again. This enables various monitoring and control tasks.
  • the slit of the first confocal aperture can have a longitudinal extension.
  • the inspection opening can in particular be arranged on an extension of the longitudinal extension.
  • the measuring device can in particular have a light guide that is connected to the inspection opening on a side opposite to the illumination imaging optics.
  • This light guide can in particular be used to guide light to the inspection opening so that it exits the inspection opening and then, as already described, takes the typical beam path that the light that reaches the detector also takes, and the light that is reflected back at the second confocal aperture as already described can also enter the inspection opening again and be picked up by the light guide so that it can be fed by the light guide to a possibility for evaluation.
  • the measuring device can in particular have a control light source which couples control light into the light guide.
  • This can be a light-emitting diode, for example.
  • a further beam path is implemented which runs parallel to the other beam path, for example, but does not reach the detector, but is reflected back and again enters through the control opening.
  • the control light source can be used in particular, which can be different from the light source already described, so that, for example, a different spectrum and/or a different intensity can be used.
  • the measuring device can in particular have a control detector which is optically coupled to the light guide and detects light entering through the control opening from the side of the illumination imaging optics. This allows the light reflected back to be measured and used, for example, for evaluation, monitoring or optimization.
  • the control detector can be wavelength-selective or wavelength-resolved or non-wavelength-resolved.
  • the coupling can be made, for example, via a fiber coupler.
  • the light guide can be optically coupled to the detector, in particular for detecting light entering through the inspection opening from the side of the illumination imaging optics. This allows the use of the detector, which is already present and has already been described above, to evaluate the reflected light. For example, a channel not used for the light passing through the imaging optics can be used for this purpose.
  • control detector or the detector can be used for this purpose, or that both the control detector and the detector can be used for this purpose.
  • the light guide can, for example, guide the light both to the control detector and to the detector.
  • the measuring device can in particular have a control device which is configured to determine a brightness of the reflection on the object based on detected light entering through the control opening from the side of the illumination imaging optics.
  • a control device which is configured to determine a brightness of the reflection on the object based on detected light entering through the control opening from the side of the illumination imaging optics.
  • the brightness can be used, for example, to control the object, whereby it can be known, for example, which reflectivity the expected object has. a specific point in time or in general, whereby a deviation from the brightness, which is, for example, absolutely or relatively greater than a specified threshold value, can be used to conclude that the wrong object is being measured.
  • a signal can be emitted and/or a measurement interrupted.
  • the luminous intensity or light intensity of the light source can be adjusted.
  • the measuring device can in particular have a control device which is configured to detect a misalignment of the measuring device based on detected light entering through the control opening from the side of the illumination imaging optics and based on the light detected by the detector passing through the second confocal aperture.
  • a control device which is configured to detect a misalignment of the measuring device based on detected light entering through the control opening from the side of the illumination imaging optics and based on the light detected by the detector passing through the second confocal aperture.
  • it can be known or specified which ratio certain intensities of the two light detections should have.
  • a misalignment can be concluded, for example, from a deviation from such a ratio, which is, for example, absolutely or relatively greater than a specified threshold value.
  • a signal can be output and/or a measurement can be interrupted automatically so that an adjustment can be made before further measurements are carried out.
  • the first confocal aperture can have a slot through which light from the light source passes, and can also expediently have at least one return opening, which is arranged next to the slot.
  • the second confocal aperture can at least be mirrored in such a way that light emerging from the slot of the first confocal aperture in the direction of the illumination imaging optics is reflected back onto at least one return opening, at least when an object is arranged.
  • the return opening can in particular be arranged in such a way that it is not illuminated by returning light in all orientations or reflection properties of objects, but only in certain situations, in particular in the case of certain objects or certain orientations of the object.
  • several return openings can be formed in the first confocal aperture.
  • the slot can in particular have a longitudinal extension, and each return opening can in particular be arranged adjacent to a long side of the slot.
  • This can in particular mean that the respective return opening is located in an area which results from a widening of the long sides of the slot in a direction transverse to the long extension of the slot. This makes it possible in particular for light which is reflected to the return openings not to always run alongside other light, but can also intersect it, for example.
  • the measuring device advantageously has at least one return detector, which is designed to detect light entering through a return opening from the side of the illumination imaging optics.
  • the measuring device can have at least one light guide, which guides light entering through a return opening from the side of the illumination imaging optics to the detector for detection. This makes it possible to measure an intensity and/or a spectral composition of the light that has returned and passed through a return opening. This can be used for evaluation purposes.
  • the first confocal aperture has two return openings, in particular exactly two return openings, which can be arranged in particular on both sides of the slot.
  • the slot is located between the two return openings. This enables measurement of light reflected back on both sides of the slot.
  • the measuring device can in particular have a return evaluation device which is designed to detect a misalignment of the measuring device based on detected light passing through one or more return openings. In this way, such a misalignment can in particular be detected and a signal can be output accordingly and/or a further measurement can be interrupted so that a misalignment can be expediently corrected first.
  • a misalignment ratios can be formed, compared with limit values, a temporal progression can be determined and/or changes outside of limit values can be detected. In particular, values that come from different return openings can be compared for this purpose.
  • the slit of the second confocal aperture can in particular have a rectangular shape and/or be elongated. This can in particular ensure that the light can penetrate to the detector along a certain width after passing through the imaging optics.
  • the measuring device has a light guide arrangement which is designed to guide part of the light emitted by the light source directly to the detector. This can in particular enable additional evaluation, for example as described in more detail below.
  • the light guide arrangement can be designed to guide light to the detector without passing through the illumination imaging optics and the detection imaging optics. This can be understood in particular as a direct guidance of light to the detector. It can also be understood as an alternative formulation.
  • the light guide arrangement can in particular be designed to guide at least part of the light to the detector without splitting the wavelengths. It can also be designed to guide the light it guides to the detector completely to the detector without splitting the wavelengths. This enables an evaluation of the entire intensity of this light, for example.
  • the light guide arrangement can be designed to split light completely or partially according to wavelength and then guide it to the detector. This can enable wavelength-resolved detection.
  • the detector can be designed in particular to detect the light received from the light guide arrangement and split into wavelengths in a wavelength-resolved manner. This enables wavelength-resolved evaluation, which can be used, for example, as described below.
  • the light guide arrangement can in particular have a prism or a grating for splitting the light according to wavelengths.
  • the light guide arrangement directs light for splitting onto a prism on the detector side or onto a grating of the detector or a spectrometer. This can split the light, whereby either existing elements or additional elements can be used.
  • the measuring device can in particular have an evaluation device for light guided from the light guide arrangement to the detector. This allows additional evaluation tasks to be implemented, for example those which are described in more detail below.
  • the evaluation device can in particular be configured to standardize the intensity of the light guided by the imaging optics to the detector based on an intensity of the light guided by the light guide arrangement to the detector. This can, for example, compensate for intensity fluctuations in the light source.
  • the light guided by the imaging optics to the detector can be standardized by dividing its measured intensity or wavelength-dependent intensity by the value of an intensity that is assigned to the light guided by the light guide arrangement to the detector.
  • the evaluation device is configured to check a function of the light source based on an intensity of the light guided by the light guide arrangement to the detector.
  • This allows a simple check of the light source, in particular whether it emits light or not, and/or whether it emits light at a predetermined intensity.
  • This makes it possible to detect, for example, whether a possible failure to detect light that should pass through the imaging optics is due to a malfunction of the light source or possibly due to an object that is typically required to reflect the light not being present, for example.
  • a malfunction of the light source can be detected, for example, if the intensity of the light directed from the light guide arrangement to the detector falls below a certain threshold or is not present.
  • the evaluation device can, for example, be configured to perform a white balance for the light guided through the imaging optics or for measuring light based on a wavelength-resolved intensity of the light guided by the light guide arrangement to the detector.
  • the measuring light can in particular be the light that has passed through the imaging optics and was reflected on the object.
  • the measuring light can in particular be corrected by means of a white balance before a height determination or another evaluation takes place. This makes it possible, for example, to detect spectral changes in the light source and to make a correction accordingly by means of white balance. This improves the evaluation or recognition of other properties of the object.
  • the evaluation device can be configured in particular to compare a spectrum of the light guided through the imaging optics onto the detector with a spectrum of light guided through the light guide arrangement and to check the measuring device based on this. This allows various checking functions to be implemented, which can, for example, provide an indication of incorrect alignment or incorrect positioning or alignment of an object.
  • the spectrum of the light directed through the imaging optics onto the detector can be generated using a reflective object at different heights.
  • an object that reflects in a suitable manner can be used for this purpose.
  • the height of an object can be varied so that different focal points are located on the object and corresponding wavelengths are reflected. This makes it possible to record a spectrum that is based on different heights of an object and thus on different reflected wavelengths.
  • the light guide arrangement can in particular have a fiber for guiding the light. This can be a glass fiber, for example. Several fibers can also be used. However, paths in which the light is guided through air can also be provided.
  • the light guide arrangement can in particular absorb light between the light source and the first confocal aperture.
  • light is emitted by the light source and reaches partly the first confocal aperture, partly the light guide arrangement and is guided by the light guide arrangement directly to the detector as mentioned above. This means that light that is as unadulterated as possible and has not yet passed through other optical elements can be coupled into the light guide arrangement.
  • the measuring device has a backlight source which is configured to emit backlight at the second confocal aperture onto the detection imaging optics.
  • a backlight beam can be generated that runs through the detection imaging optics, is reflected on the object and then runs through the illumination imaging optics. It can be used for further checking or optimization tasks. It can be said that for the purposes of backlight, the illumination imaging optics and the detection imaging optics swap their respective functions compared to the light directed at the detector. They are thus functionally linked.
  • the backlight can be directed onto the object by the detection imaging optics. This makes it possible to create a beam path, which, for example, corresponds to the inverse of the beam path already described.
  • the backlight can be reflected from the object in the same way as the light incident from the illumination imaging optics.
  • the detection imaging optics can have the same effect for the backlight as the illumination imaging optics for the light emitted by the light source described above.
  • the backlight can be directed opposite to the light from the light source, which passes through the first confocal aperture to the illumination imaging optics. In particular, it can be antiparallel to the light from the light source when coupled in.
  • the backlight source can have a laser for generating the backlight and/or the backlight can be or have laser light.
  • lasers are particularly advantageous because they generate a very small light beam, i.e. in particular a light beam with a small diameter. This can in particular be in the optical wavelength range. It can then also be easily visible to the naked eye.
  • the use of laser light allows the use of a very well-known discrete wavelength. This can be processed by the optical elements according to its wavelength.
  • the backlight source can in particular have a source with a continuous spectrum and/or the backlight can be or have a light with a continuous spectrum. This allows several wavelengths to be used simultaneously. Alternatively or additionally, the backlight source can also emit light with several discrete wavelengths or with several non-overlapping wavelength ranges. This allows different discrete wavelengths or different non-overlapping wavelength ranges to be observed separately.
  • the above-mentioned embodiments regarding the use of a laser, a continuous spectrum or discrete wavelengths or non-overlapping wavelength ranges can also be combined with one another as desired.
  • one or more discrete wavelengths and/or one or more wavelength ranges of the backlight source outside the spectrum of the light source. This allows for the implementation of more advanced functionality that would not be possible with the spectrum of the light source. For example, the height of an object can be determined even outside of the focus points induced by the spectrum of the light source.
  • the measuring device can have a backlight detector for detecting the backlight after it has passed through the detection imaging optics and the illumination imaging optics.
  • the backlight is typically reflected from the object between the detection imaging optics and the illumination imaging optics.
  • the backlight detector enables the backlight to be measured, for example an intensity or a wavelength-dependent intensity, and thus enables various evaluations.
  • the measuring device can in particular have an evaluation device. This can in particular be configured to determine an estimate of a height of the object based on respective intensities of the discrete wavelengths or the wavelength ranges. This can in particular enable a quick estimate, which can work faster, for example, because the backlight has a less complex spectrum, in particular compared to the light source, and/or has wavelengths that are not present in the light source. For example, by using only a few discrete wavelengths, for example four discrete wavelengths, a first estimate of a height of the object can be determined, which can then be used for a more precise height determination. The more precise height determination can be carried out, for example, by means of the light emitted by the light source and detected by the detector.
  • the second confocal aperture can in particular have a slit through which light passes to the detector, the slit having a longitudinal extension, and the backlight source can in particular emit the backlight in whole or in part on an extension of the longitudinal extension or it can be directed there. At this point, the backlight can then pass through the second confocal aperture or an opening formed therein and can thus reach the detection imaging optics.
  • the second confocal aperture can in particular have a slot through which light passes to the detector, the slot having a longitudinal extension.
  • the backlight source can in particular emit the backlight completely or partially adjacent to a long side of the slot. This can in particular mean that the backlight exits the second confocal aperture or an opening formed therein at a point which is defined by an extension of the long sides of the slot in a direction transverse to the long side of the slot.
  • the light source can be, for example, a lamp, in particular a light-emitting diode or comprising several light-emitting diodes, which does not only emit monochromatically. It can be provided that several different discrete wavelengths are emitted. It can also be provided that a continuous spectrum of wavelengths is emitted. In both cases, it is not a monochromatic light source.
  • a continuous spectrum can be designed in particular over a certain range of wavelengths such that for each wavelength within this range there is a non-vanishing intensity, which can be measured for example by means of a spectrometer and/or is above a respective or general threshold value.
  • An aperture is basically an object that extends over a certain area and has one or more openings and/or one or more slits through which light can pass.
  • the first confocal aperture is typically arranged optically immediately after the light source. The light from the light source typically passes through an opening in the first confocal aperture.
  • the second confocal aperture also typically has an opening through which light passes from the detection imaging optics to the detector.
  • the line segment is typically the segment in which there are actually focal points due to the wavelength spectrum or the emitted wavelengths of the light source and the illumination imaging optics. If the object intersects this line segment, a focal point of a certain wavelength will lie on the surface of the object, and it can be assumed that It is precisely at such a wavelength that a particularly high and precise reflection occurs on the object. This ultimately makes it possible to determine which wavelength has a focal point that is located on the surface of the object, which in turn makes it possible to measure the object.
  • the line segment can be straight, but it can also be curved or have a more complex shape.
  • the focal length of the first lens system for a first wavelength of the light source can differ in particular from the focal length of the first lens system for a second wavelength of the light source by an amount df.
  • the quotient of df and the focal length of the first lens system for a wavelength between the first wavelength and the second wavelength can in particular be more than 5%. For typical applications, this is considered to be sufficient aberration, which ensures a suitable arrangement of the focus points.
  • wavelengths within the spectrum of the light source can be considered here. In particular, these can be arranged between a longest wavelength and a smallest wavelength that the light source emits.
  • the longitudinal splitting of the focus point positions can be at least 0.1 times the lateral splitting of the focus point positions.
  • the longitudinal splitting which can be measured in particular along an optical axis of the first lens system of the illumination excitation optics, can in particular be smaller than the lateral splitting, which is measured transversely to the optical axis.
  • the optical axis can assume an angle of at least 20° or at most 45° to a typical sample surface.
  • the first lens system can in particular comprise at least one lens with an Abbe number of less than 40. Such lenses have proven to be advantageous for the application relevant here.
  • the line segment that passes through the focus point positions of the different wavelengths can in particular have an angle of less than 60° and/or greater than 30°, or of 45°, to a central axis of the first lens system. This means that the light falls obliquely onto a surface of the object, so that the light is also reflected obliquely.
  • the illumination imaging optics can in particular comprise a collimator lens which is arranged between the light source and the first splitting optical element. However, it can also be provided that no such collimator lens is provided or that the collimation is implemented by a plurality of lenses. It can also be provided that the splitting optical element or the first part of the splitting optical element carries out a collimation. However, the measuring device can also be operated without collimation.
  • the light can hit the first splitting optical element in a collimated manner.
  • the light can also hit the first part of the splitting optical element in a collimated manner. This makes it possible to achieve a defined beam guidance in front of the first splitting optical element, so that subsequent targeted focusing is advantageously possible.
  • the collimated passage through the prism minimizes imaging errors caused by this.
  • the first splitting optical element or the first part of the splitting optical element can in particular be a grating.
  • the first lens system can in particular comprise at least one diffractive lens. Such a diffractive lens can in particular be advantageously combined with the mentioned grating.
  • the first lens system can in particular have a central axis which is aligned at an inclination to a beam direction in front of the first splitting optical element or in front of the first part of the splitting optical element.
  • Light with a wavelength fO of the wavelengths emitted by the light source can fall on the first lens system in particular parallel to the center axis of the first lens system. This can apply to a wavelength fO in the spectrum of the light source.
  • the wavelength fO is close to the center of the spectral range of the light source. It is then referred to as the center wavelength.
  • Other wavelengths can typically take a certain angle to this.
  • the first confocal aperture can in particular be a slit aperture.
  • a slit aperture is understood to mean an aperture with a slit which is significantly more extensive in one spatial direction (longitudinal direction), in particular by at least one order of magnitude or a factor of 10, than in another spatial direction.
  • the two spatial directions can in particular be perpendicular to one another and/or define a plane of the slit aperture.
  • a focus line is formed for each wavelength, which is arranged along a surface segment which forms an acute angle to the center axis of the first lens system.
  • the focus points can lie on a respective focus line.
  • focus lines are formed at different locations instead of focus points, which lie on a surface segment instead of along a line segment, one dimension of which corresponds to the long edge of the slit aperture and the other dimension of which has all the properties of the line segment described above. All features described in relation to focus points and line segments apply analogously to focus lines and surface segments.
  • the illumination imaging optics are designed such that the focus lines of different wavelengths are formed at different locations, the locations being located along a surface segment that forms an acute angle to the center axis of the first lens system.
  • the measuring device is designed to measure an object that intersects the surface segment.
  • the second confocal aperture is typically designed as a slit aperture corresponding to the first confocal aperture.
  • the detection imaging optics can in particular comprise a second splitting optical element or the second part of the splitting optical element, which is designed as a prism or grating. It can also comprise a second lens system.
  • the detection imaging optics can be designed completely or at least essentially mirror-symmetrically to the illumination imaging optics. In this case, the line segments on which the focus points of the different wavelengths are located are advantageously aligned along the mirror plane.
  • the second splitting optical element can in particular be of identical construction and/or mirror-symmetrical to the first splitting optical element.
  • the first part of the splitting optical element can be of identical construction or mirror-symmetrical to the second part of the splitting optical element.
  • the second lens system can in particular be of identical construction to the first lens system.
  • the detector can in particular comprise a spectrometer and can in particular be designed to determine one or more wavelengths of maximum intensity and/or one or more maximum intensities corresponding to a respective wavelength. This can be used in particular to carry out evaluations in relation to a height.
  • light from the light source can pass through the first confocal aperture and then strike the illumination imaging optics, in particular a lens of the illumination imaging optics or a splitting optical element of the illumination imaging optics or a part thereof.
  • Fig. 1 a chromatic confocal measuring device according to a first
  • Fig. 2 a chromatic confocal measuring device according to a second
  • Fig. 3a to 3c a chromatic confocal measuring device according to a third embodiment
  • Fig. 4a to 4c a chromatic confocal measuring device according to a fourth embodiment
  • Fig. 5a to 5c a chromatic confocal measuring device according to a fifth embodiment
  • Fig. 6a a chromatic confocal measuring device according to a sixth
  • Fig. 6b a pattern emerging on an object
  • Fig. 7a to 7c a chromatic confocal measuring device according to a seventh embodiment.
  • Fig. 2 falls within the scope of claim 1.
  • Fig. 1 shows a chromatic confocal measuring device 100 according to an embodiment which does not fall under claim 1 of the application. Rather, this is an embodiment which is basically known from the prior art, for example as implemented in the document mentioned at the beginning.
  • the measuring device 100 is designed to measure a surface of an object 105. In particular, this concerns the height of the surface along a vertical direction in Fig. 1.
  • the measuring device 100 has an evaluation device 110.
  • the evaluation device 110 is designed to carry out various control and evaluation tasks. Depending on its functionality, it can also be called something different.
  • the measuring device 100 has a light source 120. This emits light with a relatively broad wavelength spectrum. In particular, in the present case, this essentially covers the range of visible light.
  • a first confocal aperture 130 is formed immediately adjacent to the light source 120. In this aperture, an opening (not shown separately) in the form of a slot is formed through which the light from the first light source 120 passes. It then reaches an illumination imaging optics 200. This has a converging lens 220 on the input side and a downstream converging lens 225. These two lenses 220, 225 first collimate the light before it hits a first splitting optical element 210. They can therefore be referred to as collimator lenses.
  • the splitting optical element 210 is designed as a prism in this case. It splits the incident light depending on the wavelength, whereby different wavelengths take different directions.
  • a first lens system 230 Optically downstream is a first lens system 230, which in this case is formed from a converging lens, a diverging lens and again a converging lens, which will not be discussed in more detail here.
  • the first lens system 230 and the first splitting optical element 210 are designed together in such a way that focus points are arranged along a line segment 160 depending on the wavelength.
  • the line segment 160 is a straight line along which the focus points for different wavelengths are arranged. This means that different wavelengths of the light from the light source 120 are arranged at different locations, i.e. focus points, along the line segment 160. If such a focus point is arranged on the surface of the object 105, this wavelength is reflected particularly intensively.
  • the reflection takes place to the right onto a detection imaging optics 300.
  • the detection imaging optics 300 initially has a second lens system 330 with a converging lens, a diverging lens and again a converging lens.
  • the light then hits a second splitting optical element 310, which is again designed as a prism.
  • the second lens system 330 and the second splitting optical element 310 are designed together in such a way that the wavelength-dependent deflection for the wavelengths whose focal points coincide with a reflective surface of the object 105 is reversed.
  • this light reaches another converging lens 325 and yet another converging lens 320, which focus it on an opening (not shown) in a second confocal aperture 140. Only those wavelengths whose focal point lies on a reflective surface of the object 105 are focused back on the opening. All other Wavelengths are focused away from the opening and do not pass through it or only pass through it to a small extent. The light therefore reaches a detector 400.
  • the element 420 in turn carries out a wavelength-dependent splitting and directs the light onto a further collecting lens 430 and yet another collecting lens 440.
  • Several lines can be read out separately from one another. This allows the recording of wavelength spectra of the light incident on the detector 400.
  • the second confocal aperture is a slit aperture
  • the slit is imaged over a plurality of rows of the matrix detector, so that each row records a spectrum for a different passage location along the slit aperture. In this way, several points along the object surface can be measured simultaneously.
  • the lenses 410, 430, 440 and the element 420 together form a spectrometer 405.
  • the evaluation device 110 By determining a maximum of the intensity in this wavelength spectrum, which is measured by the sensitive surface 450, the evaluation device 110, which is communicatively connected to the detector 400, can determine the height of the object 105.
  • the first and second confocal apertures 130, 140 are slit apertures and the detector 400 is a matrix detector which outputs a spectrum along a plurality of lines, a maximum can be determined for each of the spectra, whereby an entire height profile along the focus line can be determined simultaneously.
  • Fig. 2 shows a measuring device 100 according to a second embodiment.
  • the two splitting optical elements 210, 310 are replaced by a splitting optical element 500.
  • the splitting optical element 500 has a first part 510 and a second part 520. It also has a connecting piece 505 which firmly connects the two parts 510, 520 to one another.
  • the first part 510 and the second part 520 are made of a glass that has a higher refractive index than the glass from which the connecting piece 505 is made.
  • the two parts 510, 520 are designed as prisms, and are applied to a respective inclined first and second contact surface 507, 508 of the connecting piece 505.
  • the inclined contact surfaces 507, 508 are particularly inclined compared to an outer surface 506, which is directed downwards.
  • the first part 510 is a component of the illumination imaging optics 200.
  • the second part 520 is also a component of the detection imaging optics 300.
  • the splitting optical element 500 thus creates a mechanical and functional connection between the two imaging optics 200, 300 in the present embodiment.
  • the two parts 510, 520 act like the two splitting optical elements 210, 310 shown in the embodiment of Fig. 1 due to their prism shape.
  • the design shown in Fig. 2 achieves a permanent mechanical connection which is stable and ensures that the two parts 510, 520 have a fixed relationship in terms of position and alignment relative to each other.
  • the splitting optical element 500 from one piece or from only one material, for example from only one type of glass.
  • a cheaper material can be used, in particular for the connecting piece 505.
  • the two parts 510, 520 can in particular be glued onto the connecting piece 505.
  • the connecting piece 505 contributes a smaller part to the color splitting, the majority is realized by the two parts 510, 520.
  • the connecting piece 505 can be designed as a continuous cuboid.
  • Fig. 3a shows a measuring device 100 according to a third embodiment.
  • Fig. 3b shows a bottom view of the first confocal aperture 130.
  • Fig. 3c shows a bottom view of the second confocal aperture 140. The same applies to Figs. 4 and 5 described below.
  • the first confocal aperture 130 has an elongated slot 132.
  • the light emitted by the light source 120 passes through this and reaches the illumination imaging optics 200.
  • the first confocal aperture 130 also has a control opening 134. In the present case, this is round and arranged exactly in an extension of a longitudinal extent of the slot 132.
  • a light guide 135 is connected to the top of the inspection opening 134.
  • a control light source 136 and a control detector 138 are in turn connected to this.
  • the control light source 136 emits light into the light guide 135, which in turn guides it to the inspection opening 134. This light exits there and, along with the light from the light source 120, reaches the illumination imaging optics 200.
  • the light from the control light source 136 is also referred to as control light. It follows the intended beam path through the illumination imaging optics 200, reaches the object 105, is reflected there and reaches the detection imaging optics 300. From there it reaches the second confocal aperture 140, which, according to the illustration in Fig. 3c, also has an elongated slot 142.
  • the second confocal aperture 140 does not have another opening; instead, it is mirrored outside the slot 142.
  • the control light is thus reflected back by the second confocal aperture 140 and again reaches the detection imaging optics 300, from there onto the surface of the object 105 and from there again into the illumination imaging optics 200.
  • This focuses the control light back into the control opening 134, and it reaches the control detector 138 via the light guide 135. Additional light is thus available, which passes through the intended beam path not just once, but twice.
  • the two imaging optics 200, 300 swap their function during the second pass.
  • the control opening 134 can, for example, be arranged at a distance of at least 5 mm or at most 20 mm, or 10 mm, laterally to an optical axis of the converging lens 220.
  • the control light source 136 can, for example, be designed as a light-emitting diode.
  • the control light source 136 can, for example, behave like another field point, except that the light is not evaluated in the detector 400, but rather, after being reflected by the mirrored second confocal aperture 140 on the spectrometer side, reaches the control detector 138 via the light guide 135 or a fiber coupler. In such a configuration, no light is lost in the normal measuring channels and additional information can be obtained via the control detector 138.
  • the reflectivity of the object 105 can be measured very quickly in this way and a dynamic brightness adjustment can be carried out.
  • the signal detected by the control detector 138 can be used for this.
  • the double pass makes the control light more sensitive for measuring brightness.
  • the brightness is recorded in a square.
  • the described embodiment also has the advantage that there is typically more space on the side of the first confocal aperture 130 and therefore such an implementation is easier to install.
  • the brightness value of the control light can be compared with a maximum brightness value in the detector 400. If both slits 132, 142 are misaligned with respect to one another, typically not enough light reaches the detector 400, but the control light continues to be reflected. For this purpose, the entire second confocal aperture 140, apart from the slit 142, can be mirrored. The control light returns accordingly. If significantly less light reaches the detector 400 than is measured at the control detector 138 - possibly corrected by a calibration factor - this can indicate a misalignment of optical components.
  • Fig. 4a to 4c show a modification of the third embodiment. They thus show a chromatic confocal measuring device 100 according to a fourth embodiment.
  • a return opening 133 is arranged in the first confocal aperture 130. This is not arranged in the extension of a longitudinal extent of the slot 132, but directly adjacent to a long side of this slot 132. This is shown in Fig. 4b.
  • a light guide 135 is also connected to the return opening 133, which leads to a return detector 137. The return detector 137 thus registers light that enters through the return opening 133.
  • the second confocal aperture 140 is mirrored on the bottom adjacent to the slot 142.
  • light that does not pass through the slot 142 is reflected and runs through the imaging optics 200, 300 and a reflection on the object 105 to the return opening 133. It is then detected by the return detector 137.
  • the return detector By means of the return detector or the light detected by it, for example, information on the presence or absence of light can be obtained. Several such return detectors with respective return openings can also be used, in which case, for example, intensities can then be compared. Because light passes through in both directions and is also detected again on the side of the illumination imaging optics 200, both imaging optics 200, 300 each have the same function. In principle, light that strikes next to the long side of the slot 142 of the second confocal aperture 140 can be used here.
  • a return opening 133 may indicate that optical components are misaligned.
  • this can be used to perform a regular test measurement with a flat object.
  • a comparison can be made, for example, using reference intensities.
  • respective return openings 133 with respective return detectors 137 can also be arranged on both sides of the slot. This can, for example, prevent the slot 132 and/or the slot 142 from being twisted in the case of a flat object 105. can be detected.
  • the design according to the fourth embodiment has the particular advantage that light is less laterally offset and more light can be captured again.
  • FIG. 5a to 5c show a measuring device 100 according to a fifth embodiment.
  • a light guide arrangement 146 is provided which receives light directly from the light source 120 and directs it directly to the detector 400.
  • an opening 144 is formed in the second confocal aperture 140, to which the light guide arrangement 146 is connected.
  • light is guided directly from the light source 120 to the detector 400, bypassing the imaging optics 200, 300 and the object 105.
  • part of the light from the light source 120 can be diverted, for example at a solid angle that does not enter the illumination imaging optics 200.
  • This light is then guided directly to the detector 400 and can be measured, for example, by a channel of the detector 400 that is not used for the other measurement.
  • a spectral splitting can take place in the manner already described.
  • White balance is understood in particular to mean that a spectrum of the light source 120 is determined; this can be done, for example, using the light guided through the light guide arrangement 146. Measured values of the light passing through the imaging optics 200, 300 can then be corrected by dividing by the spectrum of the light source, whereby a wavelength dependency can be compensated. In addition, a check of the correct functioning of the light source 120 can be implemented in a simple manner.
  • Fig. 6a shows a measuring device 100 according to a sixth embodiment.
  • a backlight source 600 is provided.
  • the backlight source 600 is connected to a light guide 610, which leads to the second confocal aperture 140.
  • the backlight source 600 thus ultimately emits backlight at the second confocal aperture 140 onto the detection imaging optics 300. From there, the backlight reaches the object 105.
  • Fig. 6b shows a possible pattern on the upper surface of the object 105. Measuring light 106, which is irradiated by the light source 120 through the illumination imaging optics 200, and backlight 107, which comes from the backlight source 600, are superimposed. Different patterns, which are shown in Fig. 6b, correspond to different colors.
  • the backlight 107 thus runs in the opposite direction to the measuring light 106 in the beam path.
  • the backlight 107 can in particular have only a single wavelength, for example by using a laser light for this purpose.
  • the measuring light 106 typically has the character of a rainbow on the object 105.
  • the backlight 107 can, however, also have a broader spectrum.
  • the height of the object 105 can be determined.
  • a backlight 107 can be used for this, which has a single wavelength approximately in the middle of the measuring range or at another point in the measuring range, i.e. in the spectrum of the light source 120.
  • green light can be used.
  • the object 105 is positioned in the middle of the measuring range. If the point of the backlight 107 is in or beyond the blue spectral range, the object 105 is positioned above the middle. If the backlight 107 is in the red spectral range, the object 105 is positioned below the middle. This can be used to adjust the object 105.
  • white light is used as backlight, you can see, for example, two inverted rainbows, which can be pushed over one another by adjusting the height.
  • a color that crosses at a measuring point 108, i.e. is identical, is the one that is used for measuring in the current position.
  • Fig. 7a to 7c show a measuring device 100 according to a seventh embodiment. This is based on the sixth embodiment just described.
  • backlight is directed onto the detection imaging optics 300 via a backlight source 600 on the second confocal aperture 140.
  • a backlight detection opening 620 is also provided in the first confocal aperture 130. The backlight can be measured at the first confocal aperture 130 via detectors (not shown in detail).
  • a photodetector for four wavelengths for example 450 nm, 500 nm, 600 nm and 750 nm, can be used to detect the backlight.
  • the backlight can in particular be designed so that it contains at least these wavelengths.
  • the backlight is coupled in on the side of the second confocal aperture 140.
  • the opening 605 for the backlight source 600 is slightly offset from the slot 142, in this case adjacent to a long side of the slot 142.
  • the backlight can come from the light source 120, or it can come from a single LED or another backlight source.
  • a blue peak can also be used, for example, or optionally light in the range from 700 nm to 800 nm, for example 750 nm or 780 nm.
  • the backlight is evaluated at discrete wavelengths, for example at the four wavelengths mentioned above or other wavelengths mentioned.
  • Distance information can be obtained via the discrete intensities. Although this can be relatively inaccurate, it has two advantages.
  • a larger measurement range can be effectively covered if wavelengths in the blue (for example 450 nm) and red (for example 750 nm) range can also be detected. In particular, this can mean that a distance can still be measured even if the object 105 is too high or too low to be measured in terms of its height using the detector 400.
  • the measurement described is faster than the measurement using the detector 400 because only four discrete detectors are read out and evaluated. In principle, a number other than four, for example two, three, five, six or more, detectors and corresponding wavelengths can also be used.
  • the backlight is in the opposite direction to the measuring light and therefore does not interfere with normal measuring operations. In particular, no scattered light is generated in the detector 400 by the backlight.
  • a control can be carried out, for example, in order to roughly adjust the object 105 and then measure its height precisely.
  • Chromatic confocal measuring device comprising a light source (120) which emits light of several different wavelengths and/or with a continuous spectrum of wavelengths, a first confocal aperture (130) through which light from the light source (120) passes, a second confocal aperture (140), a splitting optical element (500) with a first part (510) and a second part (520), which are designed as a prism or grating, and with a connecting piece (505), wherein the first part (510) and the second part (520) are firmly connected to one another by means of the connecting piece (505), an illumination imaging optics (200) comprising at least the first part (510) of the splitting optical element (500), and a first lens system (230) with at least one first lens, which is spatially separated from the first part (510) of the splitting optical element (500), wherein the first lens system (230) receives light from the first part (510) of the splitting optical element (500) and the effective focal length of the first lens system (230) differs for different
  • Measuring device (100) according to feature 1 characterized in that the connecting piece (505) is made of a different glass or a different material than the first part (510) and the second part (520).
  • Measuring device (100) according to feature 2 characterized in that the first part (510) and the second part (520) are made of a glass or material with a higher refractive index than the connecting piece (505).
  • Measuring device (100) according to feature 1 characterized in that the connecting piece (505) is made of the same glass or the same material as the first part (510) and/or the second part (520).
  • Measuring device (100) according to one of the preceding features characterized in that the connecting piece (505) is plate-shaped.
  • Measuring device (100) according to one of the preceding features characterized in that the first part (510) and the second part (520) are prisms which are arranged resting on the connecting piece (505) or hanging from the connecting piece (505).
  • Measuring device (100) according to one of the preceding features characterized in that the connecting piece (505) defines a non-changeable positional relationship and a non-changeable orientation of the first part (510) and the second part (520) relative to one another.
  • Measuring device (100) according to one of the preceding features characterized in that the connecting piece (505) is also arranged in the beam path of the illumination imaging optics (200) and/or the detection imaging optics (300).
  • Measuring device (100) characterized in that the connecting piece (505) together with the first part (510) forms a prism which is at least partially delimited from the rest of the connecting piece (505) by an imaginary line, and/or the connecting piece (505) together with the second part (520) forms a prism which is at least partially delimited by an imaginary line from the rest of the connecting piece (505).
  • Measuring device (100) according to one of the preceding features, characterized in that the connecting piece (505) has a continuous flat outer surface (506) on a side facing the object (105) or on a side facing away from the object (105).
  • Measuring device (100) according to one of the preceding features, characterized in that a first contact surface (507) of the connecting piece (505) contacting the first part (510) is aligned parallel to the outer surface (506) of the connecting piece (505) facing away from the first part (510) and the second part (520), and/or a second contact surface (508) of the connecting piece (505) contacting the second part (520) is aligned parallel to the outer surface (506) of the connecting piece (505) facing away from the first part (510) and the second part (520).
  • Measuring device (100) characterized in that the measuring device (100) has a carrier element, wherein the connecting piece (505) is fastened to the carrier element.
  • Measuring device (100) according to feature 16 characterized in that the first part (510) and the second part (520) are not themselves fastened to the carrier element and/or are only fastened to the carrier element by means of the connecting piece (505).
  • Measuring device (100) according to one of the preceding features characterized in that the focal length of the first lens system (230) for a first wavelength of the light source (120) differs from the focal length of the first lens system (230) for a second wavelength of the light source (120) by an amount df, wherein the quotient of df and the focal length of the first lens system (230) for a wavelength between the first wavelength and the second wavelength is more than 5%.
  • Measuring device (100) according to one of the preceding features characterized in that the illumination imaging optics (200) comprise a collimator lens (220, 225) which is arranged between the light source (120) and the first part (510) of the splitting optical element (500).
  • the illumination imaging optics (200) comprise a collimator lens (220, 225) which is arranged between the light source (120) and the first part (510) of the splitting optical element (500).
  • the illumination imaging optics (200) comprise a collimator lens (220, 225) which is arranged between the light source (120) and the first part (510) of the splitting optical element (500).
  • Measuring device (100) according to one of the preceding features characterized in that the light strikes the first part (510) of the splitting optical element (500) in a collimated manner.
  • the first part (510) of the splitting optical element (500) is a grating and the first lens system (230) comprises at least one diffractive lens.
  • Measuring device (100) according to one of the preceding features characterized in that the first confocal diaphragm (130) is a slit diaphragm, wherein a focus line is formed for each wavelength which is along a Surface segment is arranged which forms an acute angle to the center axis of the first lens system (230).
  • the detection imaging optics (300) comprises a second lens system (330).
  • Measuring device (100) according to one of the preceding features characterized in that the second part (520) of the splitting optical element (500) is structurally identical to the first part (510) of the splitting optical element (500) and/or that the second lens system (330) is structurally identical to the first lens system (230).
  • the detector (400) comprises a spectrometer (405) and is designed to determine one or more wavelengths of maximum intensity and/or one or more maximum intensities corresponding to a respective wavelength.
  • Chromatic confocal measuring device comprising a light source (120) which emits light of several different wavelengths and/or with a continuous spectrum of wavelengths, a first confocal aperture (130) through which light from the light source (120) passes, a second confocal aperture (140), an illumination imaging optics (200) comprising at least one first splitting optical element (210) which is designed as a prism or grating, and a first lens system (230) with at least one first lens which is spatially separated from the first splitting optical element, wherein the first lens system (230) receives light from the first splitting optical element and the effective focal length of the first lens system (230) differs for different wavelengths, so that the illumination imaging optics (200) are designed such that focus points of different wavelengths for at least one passage point of the light through the first confocal aperture (130) are at different Locations are formed, the locations lying along a line segment (160) which forms an acute angle to the center axis of the first lens system (230), the measuring device
  • Measuring device (100) according to feature 1 characterized in that the first confocal aperture (130) has a slot (132) through which light from the light source (120) passes, and has a control opening (134) which is arranged next to the slot (130), wherein the second confocal aperture (140) is mirrored at least in such a way that light emerging from the control opening (134) in the direction of the illumination imaging optics (200) is reflected back onto the control opening (134).
  • Measuring device (100) according to feature 2 characterized in that the slot (132) has a longitudinal extension, and the control opening (134) is arranged on an extension of the longitudinal extension.
  • Measuring device (100) according to one of features 2 to 8, characterized in that the measuring device (100) has a control device which is configured to detect an incorrect position of the measuring device (100) based on detected light entering through the control opening (134) from the side of the illumination imaging optics (200) and based on light detected by the detector (400) and passing through the second confocal aperture (140).
  • the first confocal aperture (130) has a slot (132) through which light from the light source (120) passes, and has at least one return opening (133) which is arranged next to the slot (132), wherein the second confocal aperture (140) is mirrored at least in such a way that light emerging from the slot (132) of the first confocal aperture (130) in the direction of the illumination imaging optics (200) is reflected back onto at least one return opening (133) at least when an object (105) is arranged.
  • Measuring device (100) according to one of the preceding features characterized in that the slot (142) of the second confocal aperture (140) has a rectangular shape and/or is elongated.
  • Measuring device (100) characterized in that the focal length of the first lens system (230) for a first wavelength of the light source (120) differs from the focal length of the first lens system (230) for a second wavelength of the light source (120) by an amount df, wherein the quotient of df and the focal length of the first lens system (230) for a wavelength between the first wavelength and the second wavelength is more than 5%.
  • Measuring device (100) according to one of the preceding features characterized in that the longitudinal splitting of the focus point positions is at least 0.1 times the lateral splitting of the focus point positions.
  • Measuring device (100) according to feature 23 characterized in that light with a wavelength fO of the wavelengths emitted by the light source (120) falls on the first lens system (230) parallel to the center axis of the first lens system (230).
  • the first confocal diaphragm (130) is a slit diaphragm, wherein a focus line is formed for each wavelength, which is arranged along a surface segment that forms an acute angle to the center axis of the first lens system (230).
  • Measuring device (100) according to one of the preceding features characterized in that the detection imaging optics (300) comprise a second splitting optical element (310), which is designed as a prism or grating, and a second lens system (330).
  • the second splitting optical element (310) is designed to be identical in construction to the first splitting optical element (210) and/or that the second lens system (330) is designed to be identical in construction to the first lens system (230).
  • the detector (400) comprises a spectrometer (405) and is designed to determine one or more wavelengths of maximum intensity and/or one or more maximum intensities corresponding to a respective wavelength.
  • Chromatic confocal measuring device comprising a light source (120) which emits light of several different wavelengths and/or with a continuous spectrum of wavelengths, a first confocal aperture (130) through which light from the light source (120) passes, a second confocal aperture (140), an illumination imaging optics (200) comprising at least one first splitting optical element (210) which is designed as a prism or grating, and a first lens system (230) with at least one first lens which is spatially separated from the first splitting optical element (210), wherein the first lens system (230) receives light from the first splitting optical element (210) and the effective focal length of the first lens system (230) differs for different wavelengths, so that the illumination imaging optics (200) are designed such that focus points of different wavelengths for at least one passage point of the light through the first confocal Aperture (130) are formed at different locations, the locations being located along a line segment (160) which forms an acute angle to the center axis of the first lens system (
  • Measuring device (100) according to feature 1 characterized in that the light guide arrangement (146) is configured to guide light to the detector (400) without passing through the illumination imaging optics (200) and the detection imaging optics (300).
  • the light guide arrangement (146) is designed to guide at least part of the light to the detector (400) without splitting the wavelengths.
  • the light guide arrangement (146) is designed to split light completely or partially according to wavelengths and then guide it to the detector (400).
  • Measuring device (100) according to one of features 7 to 9, characterized in that the evaluation device is configured to carry out a white balance for the light guided through the imaging optics (200, 300) based on a wavelength-selective intensity of the light guided from the light guide arrangement (146) to the detector (400).
  • Measuring device (100) according to one of features 7 to 10 characterized in that the evaluation device is configured to compare a spectrum of the light guided through the imaging optics (200, 300) to the detector (400) with a spectrum of light guided through the light guide arrangement (146) and to check the measuring device (100) based thereon.
  • Measuring device (100) according to feature 11 characterized in that the spectrum of the light guided through the imaging optics (200, 300) onto the detector (400) is generated at different heights by means of a reflecting object (105).
  • Measuring device (100) according to one of the preceding features characterized in that the light-guiding arrangement (146) has a fiber for guiding the light.
  • Measuring device (100) according to one of the preceding features characterized in that the light-guiding arrangement (146) is coupled to the second confocal aperture (140) so that light from the light-guiding arrangement (146) passes through the second confocal aperture (140) to the detector (400).
  • Measuring device (100) according to one of the preceding features characterized in that the light-guiding arrangement (146) absorbs light between the light source (120) and the first confocal aperture (130).
  • Measuring device (100) according to one of the preceding features characterized in that the focal length of the first lens system (230) for a first wavelength of the light source (120) differs from the focal length of the first lens system (230) for a second wavelength of the light source (120) by an amount df, wherein the quotient of df and the focal length of the first lens system (230) for a wavelength between the first wavelength and the second wavelength is more than 5%.
  • Measuring device (100) according to one of the preceding features characterized in that the illumination imaging optics (200) comprise a collimator lens (220, 225) which is arranged between the light source (120) and the first splitting optical element (210). Measuring device (100) according to one of the preceding features, characterized in that the light hits the first splitting optical element (210) in a collimated manner. Measuring device (100) according to one of the preceding features, characterized in that the first splitting optical element (210) is a grating and the first lens system (230) comprises at least one diffractive lens.
  • Measuring device (100) according to feature 26 characterized in that the second splitting optical element (310) is constructed identically to the first splitting optical element (210) and/or that the second lens system (330) is constructed identically to the first lens system (230).
  • the detector (400) comprises a spectrometer (405) and is designed to determine one or more wavelengths of maximum intensity and/or one or more maximum intensities corresponding to a respective wavelength.
  • Measuring device (100) according to feature 1 characterized in that the backlight is directed by the detection imaging optics (300) onto the object (105).
  • Measuring device (100) according to one of the preceding features characterized in that the backlight is directed opposite to the light from the light source (120), which passes through the first confocal aperture (130) to the illumination imaging optics (200).
  • Measuring device (100) according to one of the preceding features characterized in that the backlight source (600) has a laser for generating the backlight and/or the backlight is or has laser light.
  • the measuring device (100) has an evaluation device (110) which is configured to determine an estimate of a height of the object (105) based on respective intensities of the discrete wavelengths or the wavelength ranges.
  • Measuring device (100) according to one of the preceding features, characterized in that the second confocal diaphragm (140) has a slit (142) through which light passes to the detector (400), wherein the slit (142) has a longitudinal extension and the backlight source (600) emits the backlight completely or partially on an extension of the longitudinal extension.
  • Measuring device (100) according to one of the preceding features, characterized in that the second confocal aperture (140) has a slit (142) through which light passes to the detector (400), the slit (142) having a longitudinal extension and the backlight source (600) emits the backlight completely or partially adjacent to a long side of the slit (142).
  • Measuring device (100) characterized in that the focal length of the first lens system (230) for a first wavelength of the light source (120) differs from the focal length of the first lens system (230) for a second wavelength of the light source (120) by an amount df, the quotient of df and the focal length of the first lens system (230) for a wavelength between the first wavelength and the second wavelength being more than 5%.
  • Measuring device (100) according to one of the preceding features characterized in that the longitudinal splitting of the focus point positions is at least 0.1 times the lateral splitting of the focus point positions.
  • Measuring device (100) according to one of the preceding features characterized in that the light hits the first splitting optical element (210) in a collimated manner.
  • Measuring device (100) according to one of the preceding features characterized in that the first splitting optical element (210) is a grating and the first lens system (230) comprises at least one diffractive lens.
  • Measuring device (100) according to one of the preceding features characterized in that the first lens system (230) has a center axis which is aligned at an incline to a beam direction in front of the first splitting optical element (210).
  • Measuring device (100) according to feature 19 characterized in that light with a wavelength fO of the wavelengths emitted by the light source (120) falls on the first lens system (230) parallel to the center axis of the first lens system (230).
  • the first confocal diaphragm (130) is a slit diaphragm, wherein a focus line is formed for each wavelength, which is arranged along a surface segment that forms an acute angle to the center axis of the first lens system (230).
  • Measuring device (100) according to one of the preceding features characterized in that the detection imaging optics (300) comprise a second splitting optical element (310), which is designed as a prism or grating, and a second lens system (330).
  • the second splitting optical element (310) is designed to be identical in construction to the first splitting optical element (210) and/or that the second lens system (330) is designed to be identical in construction to the first lens system (230).
  • the detector (400) comprises a spectrometer (405) and is designed to determine one or more wavelengths of maximum intensity and/or one or more maximum intensities corresponding to a respective wavelength.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Optics & Photonics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

L'invention concerne un dispositif de mesure confocal chromatique comprenant une source de lumière et une optique d'imagerie. Le dispositif de mesure est conçu pour mesurer un objet qui coupe un segment de ligne qui est défini par des points focaux de différentes longueurs d'onde. Le dispositif de mesure comporte un élément de séparation doté de parties dans les deux optiques d'imagerie.
PCT/EP2023/086833 2022-12-20 2023-12-20 Dispositif de mesure confocal chromatique WO2024133386A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102022134242.5 2022-12-20
DE102022134242.5A DE102022134242A1 (de) 2022-12-20 2022-12-20 Chromatisch konfokale Messeinrichtung

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WO2024133386A1 true WO2024133386A1 (fr) 2024-06-27

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011117523B3 (de) * 2011-11-03 2013-04-18 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung zur optischen Bestimmung der Oberflächengeometrie einer dreidimensionalen Probe
DE102018130901A1 (de) 2018-12-04 2020-06-04 Precitec Optronik Gmbh Optische Messeinrichtung
CN111486952A (zh) * 2020-06-02 2020-08-04 南京引创光电科技有限公司 一种光学测量系统
US20200378743A1 (en) * 2017-12-18 2020-12-03 Universitat Stuttgart Method and assembly for chromatic confocal spectral interferometry or spectral domain oct

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102022202778B4 (de) 2022-02-11 2024-05-16 Micro-Epsilon Optronic Gmbh System und Verfahren zur konfokal-chromatischen Linienabstandsmessung

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011117523B3 (de) * 2011-11-03 2013-04-18 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung zur optischen Bestimmung der Oberflächengeometrie einer dreidimensionalen Probe
US20200378743A1 (en) * 2017-12-18 2020-12-03 Universitat Stuttgart Method and assembly for chromatic confocal spectral interferometry or spectral domain oct
DE102018130901A1 (de) 2018-12-04 2020-06-04 Precitec Optronik Gmbh Optische Messeinrichtung
CN111486952A (zh) * 2020-06-02 2020-08-04 南京引创光电科技有限公司 一种光学测量系统

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