Measurement system with chromatic range sensor and collision protection

Abstract

This provides a method for reducing or eliminating potential damage to an optical pen caused by collisions with other objects. [Solution] A measurement system 500 is provided, comprising a chromatic range sensor optical pen 120, a measuring device, and an optical pen moving structure 540. The optical pen 120 focuses different wavelengths at different distances in the vicinity of the workpiece to be measured. The measuring device adjusts the relative position between the optical pen and the workpiece (for example, to use the optical pen to measure the workpiece). The optical pen moving structure 540 includes a top portion attached to the optical pen and configured to move in the positive axial direction (for example, relative to a holder attached to the measuring device). When a corresponding force in the positive axial direction is applied by the optical pen coming into contact with the workpiece or another object (for example, corresponding to a collision), the optical pen becomes movable from its standby position (thus minimizing any potential damage).

Description

Technical Field

[0001] The present disclosure generally relates to precision measurement instruments, and more particularly to a chromatic range sensor that can be used with a measuring device for determining a measurement value of a workpiece.

Background Art

[0002] It is known to use chromatic confocal techniques in optical distance sensors (such as sensors including height, distance, etc.). As described in U.S. Patent No. 7,876,456 ('456 patent), which is hereby incorporated by reference in its entirety, by using an optical element having axial chromatic aberration (also called axial chromatic aberration or longitudinal chromatic dispersion), a broadband light source can be focused so that the axial distance to the focus changes according to the wavelength. Thereby, only one wavelength is accurately focused on the surface, and which wavelength is best focused is determined according to the surface height or distance with respect to the focusing element. After being reflected by the surface, the light is re-focused on a small aperture of a detector such as a pinhole or the end of an optical fiber. When reflected by the surface and returning to the input / output fiber through the optical system, only the wavelength that is well focused on the surface is also well focused on the aperture. All other wavelengths are not well focused on the aperture, and thus the optical power coupled into the fiber is small. Therefore, for the light returning through the fiber, the signal level is maximum for the wavelength corresponding to the surface height (i.e., the distance to the surface). In a spectrometer-type detector, the height of the surface is determined by measuring the signal level of each wavelength (for example, the wavelength that is well focused on the surface generally forms the highest peak in the overall detection signal).

[0003] Some manufacturers refer to practical and compact chromatic distance sensor (CRS) systems that operate as described above and are suitable for industrial applications as chromatic point sensors (CPS) or chromatic line sensors, etc. The compact chromatic dispersive optical assembly used with such systems is called an “optical pen” or simply a “pen.” The CRS optical pen is connected to the electronic part of the chromatic range sensor system via an optical fiber. The electronic component includes a light source that transmits light emitted from the optical pen via the optical fiber, and a spectrometer that detects and analyzes the returned light. The returned light forms a wavelength-dispersive intensity profile received by the spectrometer’s detector array. By analyzing the pixel data corresponding to the wavelength-dispersive intensity profile, a “dominant wavelength position coordinate” is determined, indicated by the peak or centroid of the intensity profile (e.g., corresponding to a wavelength well focused on the surface). The pixel coordinates from which the peak and / or centroid are obtained, along with a lookup table, are used to determine the distance to the surface. This pixel coordinate may be determined with sub-pixel resolution and is sometimes called a “distance-indicating coordinate” or “distance-indicating pixel coordinate.” [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In various implementation configurations, it is sometimes desirable to use the CRS optical pen in combination with a measuring device (e.g., a roundness measuring device) in various measurement applications and systems. In various implementation configurations, the CRS optical pen is connected to the measuring device, and the measuring device is capable of moving the CRS optical pen and / or the workpiece relative to each other in order to perform measurements, which can result in various problems (e.g., collisions). In relation to such problems, an improved system (e.g., including a CRS optical pen connected to a measuring device) is desirable. [Means for solving the problem]

[0005] This summary is provided to introduce some of the concepts further described below in a simplified form for modes of carrying out the invention. This summary is not intended to identify any important features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] According to one embodiment, a measurement system is provided that includes a chromatic range sensor system, a measuring device, and an optical pen movement structure. The chromatic range sensor system has a chromatic range sensor optical pen configured to focus different wavelengths at different distances in close proximity to the surface of a workpiece to be measured. The optical pen is configured to be coupled to the measuring device in a standby position, and the measuring device is configured to adjust the relative position between the optical pen and the workpiece to be measured. The optical pen movement structure is configured to allow the optical pen to move from the standby position when a corresponding force is applied by the optical pen coming into contact with a workpiece or other object. The optical pen movement structure includes a top portion configured to be coupled to (e.g., fixedly mounted to) the optical pen and configured to move in the positive axial direction when a corresponding force is applied in the positive axial direction by the optical pen coming into contact with (e.g., corresponding to a collision) the workpiece or other object. In various implementations, the optical pen movement structure further includes a movement structure holder (e.g., fixedly mounted to the measuring device), and the top portion is coupled to the movement structure holder as part of a kinematic coupling structure.

[0007] In another embodiment, a method for operating a measurement system is provided. This method includes: using a measuring device to adjust the relative position between the optical pen and the object to be measured; and using an optical pen moving structure to enable the optical pen to move from a standby position in the positive axis direction when a corresponding force in the positive axis direction is applied by the optical pen coming into contact with (e.g., a collision with) a workpiece or other object.

[0008] In another embodiment, an optical pen movement structure for use in a measuring system is provided. The optical pen movement structure includes a top and a movement structure holder. The top is configured to be coupled to (e.g., fixedly mounted to) an optical pen. The top is coupled to the movement structure holder (e.g., fixedly mounted to a measuring device) as part of a kinematic coupling structure, and the top is configured to separate from the movement structure holder so as to allow movement of the optical pen in the positive axial direction from a standby position when a corresponding force in the positive axial direction is applied by the optical pen coming into contact with (e.g., corresponding to a collision) a workpiece or other object.

[0009] Many of the aforementioned aspects and associated advantages of the present invention will be better understood and therefore more readily understood by referring to the following detailed description in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram of an exemplary chromatic range sensor (CRS) system including an optical pen. [Figure 2] This figure shows the system noise (bias) profile from the CRS system, illustrating the wavelength-dependent voltage offset signal level for pixels in the detector array when no measurement surface is present. [Figure 3] This figure shows an intensity profile from a CRS system, illustrating effective wavelength peaks generated by wavelengths reflected from the surface, where the pixel positions of the peaks correspond to the measured distance to the surface. [Figure 4A] This figure shows the first representation of CRS distance calibration data, which correlates distance-indicating pixel coordinates with known measured distances to the measured workpiece surface. [Figure 4B] This figure shows a second representation of CRS distance calibration data, including an example of a CRS distance calibration lookup table that references distance indicator coordinates (DICs) to the corresponding measured distances in the CRS system. [Figure 5A]This is a perspective view showing an implementation of a measurement system that includes measuring devices (e.g., a roundness measuring device) used in conjunction with a CRS system for measuring objects. [Figure 5B] Figure 5A is a block diagram showing the structure of the measuring device and the control / processing unit for the CRS system. [Figure 5C] This figure shows a workpiece with a hole being measured by the measuring device and CRS system shown in Figure 5A. [Figure 6] This is an isometric view of the chromatic range sensor optical pen connected to the top of the optical pen movement structure. [Figure 7] This is a partial cross-sectional side view of a part of the optical pen movement structure. [Figure 8] This is an isometric view of the top portion of the optical pen movement structure relative to the movement structure holding portion. [Figure 9A] This is an isometric view of the arm portion of a measuring device having a movable structure holder attached and a top portion connected thereto. [Figure 9B] This is an isometric view of the arm portion of the measuring device to which the movable structure holding part is attached. [Figure 10] This flowchart illustrates one embodiment of a general routine for operating a measurement system that includes an optical pen movement structure. [Modes for carrying out the invention]

[0011] Figure 1 is a block diagram of a first type exemplary chromatic range sensor (CRS) system 100 based on an operating principle preferred for use with a measuring device. The CRS system 100 has some similarities to the systems described in U.S. Patents 7,876,456, 7,990,522, and 9,329,026 (Patents 456, 522, and 026, respectively), which are incorporated herein by reference in their entirety. As shown in Figure 1, the CRS system 100 includes an optical pen 120, an electronics unit 160, and a user interface unit 171. It will be understood that the CRS system 100 shown in Figure 1 may be a chromatic point sensor (CPS) system that measures a single measurement point at a time (i.e., the CRS optical pen 120 is the chromatic point sensor). However, in various embodiments, alternative types of chromatic range sensor systems, such as chromatic line sensors, may be used.

[0012] The optical pen 120 includes an optical fiber connector 109, a housing 131 (e.g., an assembly tube), and an optical section 150. The optical fiber connector 109 is attached to the end of the housing 131. In various embodiments, the optical fiber connector 109 may be oriented at an angle to the housing 131. The optical fiber connector 109 receives an optical fiber (not shown in detail) through an optical fiber cable 112 enclosing it. The input / output optical fiber outputs light source light through the fiber aperture 195 and receives measurement signal light reflected through the fiber aperture 195.

[0013] During operation, broadband light (e.g., white) emitted from the fiber end through the fiber aperture 195 is focused by an optical unit 150, which includes a lens or lens group that introduces axial chromatic aberration, such that the focal point along the optical axis OA is at a different distance depending on the wavelength of light, as is known for color confocal sensor systems. The light source forms a measurement beam 196, which contains wavelengths that are focused on the surface 190 (e.g., the surface of the workpiece) at position Z relative to the optical pen 120. In response to reflection from the surface 190, the reflected light is refocused onto the fiber aperture 195 by the optical unit 150. The working light source and the reflected light are bounded by limiting rays LR1 and LR2. Due to axial chromatic aberration, only one wavelength may have a forward focal length FF that coincides with the measurement distance (e.g., measurement distance Z) from the optical pen 120 (e.g., a fixed reference position RP relative to the optical pen 120) to a position on the workpiece surface 190. The optical pen is configured such that the wavelength best focused on surface 190 is also the wavelength of reflected light best focused on fiber aperture 195. Fiber aperture 195 spatially filters the reflected light, thereby primarily allowing the best focal wavelength to pass through fiber aperture 195 into the core of optical fiber cable 112. As described later and in more detail in the incorporated references, optical fiber cable 112 sends the reflected signal light to wavelength detector 162, which is used to determine the wavelength with the dominant intensity corresponding to the measurement distance to surface 190.

[0014] Figure 1 also schematically illustrates an arbitrary reflective element 155 with a dashed outline. The reflective element may be positioned in the path of the light source beam SB, as described in more detail in U.S. Patent No. 8,194,251, which is incorporated herein by reference in its entirety. In such a configuration, the measurement axis MA is not coaxial with the optical axis OA, and the reflective element can guide the measurement beam 196' along a measurement axis MA' in a different direction (e.g., perpendicular to the optical axis) as needed in some measurement applications. In such a configuration, the light source forms the measurement beam 196', which contains wavelengths that are focused onto a surface 190' (e.g., the surface of a workpiece) at a position relative to the optical pen 120 (e.g., referred to as position Z or position X in some configurations). Due to axial chromatic dispersion, only one wavelength has a forward focal length, and the forward focal length FF' (not shown), which corresponds to the measurement distance (e.g., measurement distance Z' or X) from the optical pen 120 (e.g., from a reference position RP fixed to the optical pen 120) to a position on the work surface 190', may be equivalent to / identical to the forward focal length FF described above. More specifically, the forward focal length and / or measurement distance Z' in such a configuration would be understood as the sum of two distances: the distance from the reference position RP to the axial position of the reflecting element 155, and the distance from the axial position of the reflecting element 155 to the work surface 190' (e.g., in the illustrated embodiment, the two distances are orthogonal to each other). Such an orthogonal arrangement is utilized in embodiments shown in other figures of this specification, as will be described in more detail below. With respect to such implementations, distance / position Z' may be simply referred to as distance / position Z, and / or measurement beam 196' may be simply referred to as measurement beam 196.

[0015] The electronic device unit 160 includes a fiber coupler 161, a wavelength detector 162, a light source 164, a signal processing unit 166, and a memory unit 168. In various implementation forms, the wavelength detector 162 includes a spectrometer or a spectrometer array. The dispersive optical unit (e.g., a grating) receives the reflected light through the optical fiber cable 112 and sends the resulting spectral intensity profile to the detector array 163. The wavelength detector 162 may also include associated signal processing (e.g., provided by the signal processor 166 in some embodiments) to remove or compensate for specific detector-related error components from the profile data. Some aspects of the wavelength detector 162 and the signal processor 166 may be integrated and / or indistinguishable in some embodiments. In various implementation forms, the signal processor 166 and / or the wavelength detector 162 and / or other signal processors, computing systems, etc. utilized for the associated processing may be referred to as the processing part of the CRS system 100.

[0016] The white light source 164 controlled by the signal processor 166 is coupled to the optical fiber cable 112 via an optical coupler 161 (e.g., a 2×1 optical coupler). As described above, the light passes through the optical pen 120, resulting in axial chromatic aberration where the focal length changes according to the wavelength of the light. The wavelength of the light most efficiently returned through the fiber is the wavelength that focuses on the surface 190 or 190' at the position Z. The intensity of the reflected wavelength-dependent reflected light passes through the fiber coupler 161 again, and about 50% of the light is directed towards the wavelength detector 162, which is capable of receiving a spectral intensity profile distributed over an array of pixels along the wavelength measurement axis of the detector array 163 and is operable to provide corresponding profile data as more detailed in the incorporated references.

[0017] In short, the distance indicator coordinate (DIC) with subpixel resolution of the profile data (see, for example, Figure 3) is calculated by the signal processor 166. The DIC (in subpixel units) indicates the measured distance Z (in microns) to a position on the surface 190 or surface 190' via a distance calibration lookup table, etc., which is stored in the calibration unit 169 of the storage unit 168 (see, for example, Figures 4A and 4B below). The DIC may be determined by various methods (e.g., based on the centroid of the intensity profile data included in the peak region) according to conventionally known methods. In various implementations, the profile data can be used to determine the DIC with subpixel resolution, as will be explained in more detail later.

[0018] The optical pen 120 generally has a measuring range R bounded by a minimum range distance ZMIN and a maximum range distance ZMAX. In some examples of known optical pens, the measuring range R may be about 1 / 10 of the nominal standoff or working distance from the end of the pen (e.g., ranging from a few microns to a few millimeters). In various implementations, the measuring range R may, in addition or alternatively, be referred to as and / or equal to the working range of the optical pen 120 (e.g., working range WR). Figure 1 schematically shows that when a reflective element 155 is used, the measuring range R' (e.g., this may be equal to the measuring range R) may be oriented along the measuring axis MA' determined by the arrangement of the reflective element 155. In such a case, the measuring range R' may be limited by a minimum range distance ZMIN' and a maximum range distance ZMAX'. In various implementations, the measurement range R' may, in addition or alternatively, be referred to as the working range (e.g., the working range WR of the optical pen 120) and / or be equal to the working range (e.g., the working range WR of the optical pen 120). In various implementations, the minimum range distance ZMIN' and the maximum range distance ZMAX' may, further or alternatively, be referred to simply as ZMIN and ZMAX or XMIN and XMAX (e.g., following a coordinate system with the measurement axis MA' along the x-axis).

[0019] It should be understood that in some implementations, the electronic device unit 160 may be disposed away from the optical pen 120. For example, using a customized bracket, an optical pen similar to the optical pen 120 shown in FIG. 1 can be attached onto the CMM, and an optical fiber similar to the optical fiber cable 112 can be routed to a remotely located electronic device similar to the electronic device unit 160 along a temporary path outside the CMM components.

[0020] In various implementations, a group of components in the light source and wavelength detector portion 160A (e.g., including the wavelength detector 162 and the light source 164) may be included inside the optical probe assembly in some embodiments. A group of components within the measurement signal processing and control circuit 160B (e.g., including the signal processor 166 and the storage unit 168) may be remotely located outside the optical probe assembly if desired (e.g., to maintain a small probe weight and a compact probe size).

[0021] As further shown in FIG. 1, the user interface unit 171 is connected to the electronic device unit 160 and provides a user interface configured to receive user input used for the operation of the CRS system 100, such as user commands for selecting various operation parameters, via any suitable means such as a keyboard, a touch sensor, a mouse, etc. In an exemplary embodiment, the user interface unit 171 may include one or more operation mode selection elements (e.g., user-selectable buttons) operable by the user to select one of a plurality of operation modes (e.g., a measurement mode, a calibration mode, etc.) of the CRS system 100. Also, the user interface unit 171 is configured to display information such as one or more distances normally determined or measured by the CRS system 100 on the screen.

[0022] Figure 1 includes orthogonal XYZ coordinate axes as a reference frame (for example, as part of the local coordinate system (LCS) of the optical pen 120 / CRS system 100). The Z direction may be defined to be parallel to the measurement axis MA, which is coaxial with the optical axis (OA), which can be the distance measuring axis of the optical pen 120. As shown in Figure 1, during operation, the surface 190 (e.g., that of the workpiece being measured) is positioned / placed along the measurement axis MA, which is coaxial with the optical axis OA. Alternatively, in embodiments where a reflective element 155 is used, the surface 190' (e.g., that of the workpiece being measured) is positioned / placed along the measurement axis MA'. In some such implementations, the Z direction (e.g., corresponding to the measurement distance Z) may be defined to be parallel to the measurement axis MA' (for example, as part of the local coordinate system (LCS) of the optical pen 120 / CRS system 100, the z axis and Z direction may be axes or directions of primary interest in relation to the measurement of the optical pen 120, and the Z direction may correspond to the optical axis, which is the distance measuring axis of the optical pen 120).

[0023] The following description of Figure 2 outlines some known background signal processing and / or calibration operations. Figure 2 is a diagram of the system noise (bias) profile from a CRS system, showing the voltage offset signal level Voffset(p) for pixels in the detector array (see detector array 163 in Figure 1) when no measurement surface is present within the nominal total measurement range of the CRS system. In this case, there is no intentionally reflected light, and therefore no significant or dominant wavelength peaks in the resulting intensity profile. The voltage offset signal Voffset(p) is plotted with normalized voltage for each of the 1024 pixels along the wavelength measurement axis of detector array 163. The "normalized voltage" assigns a value of 1.0 to the saturation voltage of detector array 163. The voltage offset signal Voffset(p) includes a bias signal level Vbias, which is relatively constant across the detector array, and a background signal component Vback(p), which is shown as varying across the detector array.

[0024] The variable background signal Vback(p) represents signals such as background light from wavelength-dependent spurious reflections in a chromatic point sensor, as well as signals due to the dark currents of various pixels p. In various implementations, it is advantageous for the signal component Vback(p) (or a similarly fluctuating signal such as the voltage offset signal Voffset(p)) to be stored for calibration or correction of the pixel array of the detector array 163 and used to continuously compensate (e.g., by subtraction) all subsequent profile data signals from each pixel p. Therefore, it should be understood that the background signal component Vback(p) is assumed to be compensated in known ways in various implementations and does not need to be further explicitly considered or explained in relation to the various intensity profiles or signal processing operations described below.

[0025] The following description of Figures 3, 4A, and 4B outlines a specific signal processing operation in which distance indicator coordinates (DICs) are determined with subpixel resolution based on effective wavelength peaks occurring in the wavelength-dispersed intensity profile from the CRS system, and further, the measured distance to the surface (e.g., in microns) is determined based on the determined DICs. Some previously known operations described herein are described in more detail in the '456 patent. The purpose of this description is to provide information useful for an overall understanding of some CRS measurement operations such as those described herein.

[0026] Figure 3 is a diagram 300 of the chromatic dispersion intensity profile from the CRS system, showing effective wavelength peaks 302 generated by a subset of the measurement profile signal MS(p) that indicate wavelengths focused on and reflected by a surface (e.g., a workpiece), as part of the standard operation of the CRS system. As mentioned above, as part of the standard operation of the CRS system, the signal level is maximum at wavelengths corresponding to the surface height or distance to the surface, and wavelengths that are well focused on the surface typically form the highest peak in the overall detector signal. In the example of Figure 3, diagram 300 includes wavelength peaks 302 corresponding to the measured surface. Each of the measurement profile signals MS(p) has a signal level (indicated by normalized voltage) associated with each pixel p of the detector array (e.g., detector array 163). The wavelength peaks 302 have sufficient height (good signal-to-noise ratio), are relatively symmetrical, and allow for good estimation of the peak position or measurement distance indicator coordinate (DIC) 304 along the wavelength measurement axis of the detector array. Figure 3 also shows the bias signal level MVbias (normalized voltage), peak pixel coordinates (ppc), and the data threshold MVthreshold which defines the lower limit of a subset indicating the distance of the measured profile signal MS(p) that forms the wavelength peak 302. All values ​​(including, e.g., the "MV" value) are normalized voltages.

[0027] In short, in one embodiment, a measurement operation for determining distance indicator coordinates (DIC) (in pixels) and determining the corresponding measurement distance (in microns) based on the determined DIC may include: positioning the target surface along the optical axis OA and obtaining the resulting wavelength dispersion intensity profile as shown in diagram 300; determining the peak pixel coordinates (ppc), which are the pixels with the highest signal; determining the measurement bias signal level MVbias at a given sampling rate; determining the data threshold MVthreshold (e.g., as a percentage of peak height); determining the distance indicator coordinates (DIC) at subpixel resolution based on a distance indicator subset of the measurement profile signal MS(p) that forms wavelength peaks with values ​​greater than MVthreshold; and determining the measurement distance by associating the DIC with the corresponding distance in stored distance calibration data (e.g., a distance calibration curve as shown in Figure 4A or a lookup table as shown in Figure 4B).

[0028] In the operation described above, the DIC may be determined at subpixel resolution based on a subset representing the distance of the measured profile signal MS(p) above the data threshold MVthreshold. According to conventionally known methods, the DIC may be determined as the subpixel resolution coordinates of the centroid XC of the subset representing the distance of the signal MS(p). For example, in the case of a detector having 1024 pixels (i.e., each having a corresponding number of pixels (p) from 1 to 1024), the centroid XC may be determined as follows:

[0029]

number

[0030]

number

[0031] In one specific example, n=2 in Equation 1. In Equation 2, it will be understood that the signal MS(p) used in calculating the centroid is limited to a subset representing distance.

[0032] Figure 4A is a diagram 400A showing a first representation of CRS measurement distance calibration data 410A (stored, for example, in the calibration unit 169 in Figure 1), which correlates a known measurement distance (ZOUT, in microns) along the optical axis (OA) of the CRS system with the subpixel resolution distance indicator coordinate (DIC). It should be understood that the specific values ​​in Figure 4A are intended for illustrative purposes only and may not correspond to specific values ​​shown in other embodiments (for example, specific values ​​described with respect to Figures 1-3 and / or specific table values ​​in Figure 4B, which will be described in more detail below, but the concepts will be similar). The example shown in Figure 4A relates to an optical element (e.g., an optical pen) having a nominal total measurement range MR of about 300 microns, corresponding to a DIC range of about 150 pixels to 490 pixels. However, the CRS system may be calibrated over a larger pixel range and / or different portions of the detector array 163, if desired. While the distance calibration data 410A appears to form a smooth curve, it will be understood that in some examples, in typical CRS systems, particularly low-cost CRS systems, the distance calibration data and / or output spectral profile data may exhibit certain short-range variability / irregularity (as partially described in, e.g., Patent 456).

[0033] One exemplary laboratory calibration method for determining CRS measurement distance calibration data 410A and / or CRS measurement distance calibration data 410B (which can be used, for example, for factory calibration) uses a mirror that moves along the optical axis OA (for example, surface 190 or surface 190' in Figure 1 in an exemplary implementation). The displacement of the mirror relative to the optical pen along the optical axis OA is controlled (for example, by a stepping motor, etc.), which is capable of moving the calibration measurement distance in approximately equal steps (e.g., steps of 0.1 or 0.2 microns). For each step, the actual mirror position or displacement is acquired using a reference standard such as an interferometer. For each actual mirror position, a calibration distance indicating the coordinates of the CRS system is determined based on the corresponding intensity profile data provided by the CRS detector. The calibration distance indicating coordinates and the corresponding actual position are then recorded to provide distance calibration data 410A and / or distance calibration data 410B.

[0034] After the distance calibration data is determined, in subsequent measurement operations, the workpiece surface (e.g., surface 190 or surface 190' in Figure 1) is positioned along the optical axis OA of the CRS optical pen to determine the measurement distance to the workpiece surface. The measurement distance, which represents the CRS coordinates, is determined based on the measurement DIC determined from the intensity profile data provided by the CRS detector. Subsequently, the distance calibration data (e.g., distance calibration data 410A, distance calibration data 410B, etc.) is used to determine the CRS measurement distance Z corresponding to that particular measurement DIC.

[0035] Figure 4B is a diagram 400B of a second representation of CRS distance calibration data 410B (stored, for example, in the calibration unit 169 in Figure 1) having a CRS distance calibration lookup table for referencing distance indicator coordinates for a measured distance for a chromatic point sensor. As stated above, the values ​​in the table in Figure 4B are illustrative and may not coincide with specific values ​​shown in other examples such as the example in Figure 4A, although the similarity in concept should be understood. In general, the same set of distance calibration data may be represented as a curve (for example, as illustrated in Figure 4A) or a table (for example, as illustrated in Figure 4B), and it should be understood that distance calibration data used to form one such type of representation may similarly be used to form other types of representations and / or other representations.

[0036] In Figure 4B, the left column displays the calibration DIC in increments of 0.1 pixels, covering pixel coordinates from 1 to 1,024, while the right column displays the corresponding measured distance (in microns) (ZOUT). During operation, the measured DIC calculated by the CRS system is referenced against a stored calibration lookup table to determine the corresponding measured distance (in microns). If the measured DIC lies between adjacent calibration DIC values, the measured distance may be determined, for example, by interpolation. In the example in Figure 4B, several specific exemplary values ​​are shown for several small ranges near the DIC at pixel positions of approximately 104, 604, and 990, with corresponding measured distances in the ranges of approximately 37 microns, 381 microns, and 486 microns.

[0037] During operation (for example, for a measurement distance to surface 190 or surface 190' as shown in Figure 1), the optical pen 120 is connected to the CRS electronics unit 160 and positioned operably relative to surface 190 or surface 190' to perform the measurement operation. The measurement operation includes the optical pen 120 receiving an input spectral profile from the light source 164 and outputting the corresponding radiation to surface 190 or surface 190', and the CRS wavelength detector receiving the radiation reflected from surface 190 or surface 190' and outputting the reflected radiation to provide output spectral profile data, which is then provided to the CRS wavelength detector 162. The output spectral profile includes a distance-dependent profile component and a distance-independent profile component. The distance-dependent profile component has a wavelength peak (e.g., peak 302 in Figure 3) that indicates the measurement distance from the optical pen 120 to surface 190 or surface 190' (e.g., measurement distance Z). As described above, the measured DIC determined according to the centroid calculation by the CRS system is referenced to stored distance calibration data (e.g., Figures 4A and 4B) to determine the measured distance corresponding to the measured DIC (e.g., the measured distance Z is value ZOUT). If the measured DIC is between adjacent calibration DIC values, the measured distance corresponding to the measured DIC may be determined by interpolation (e.g., between the measured distances corresponding to adjacent calibration DIC values).

[0038] Figure 5A is a perspective view showing an implementation of a measurement system 500, which includes a measuring device 510 used in conjunction with a CRS system 100 (i.e., including an optical pen 120) to measure a workpiece. Figure 5B is a block diagram showing the structure of the measuring device 510 and the control processing unit 512 for the CRS system 100 (i.e., including the optical pen electronics unit 160) shown in Figure 5A. In various implementations, the measuring device 510 may be a roundness measuring device (for example, in various implementations, it may be in the form of a roundness test device and / or a cylindrical coordinate measuring device, or otherwise may be referred to as a cylindrical coordinate measuring device). The measuring device 510 comprises a measuring unit 511 for measuring the surface shape of a workpiece OB, and a control processing unit 512 for controlling the measurement operation of the measuring unit 511 and processing the position data obtained by the measurement.

[0039] The measuring unit 511 has a base 513 fixedly positioned on a desired horizontal plane. The base 513 has a rotating stage 514 (e.g., a rotary table) that rotates the workpiece OB at a constant speed around a rotation axis (e.g., a measuring axis) perpendicular to the horizontal plane, and a head drive mechanism 516 that moves an optical pen 120 attached to / connected to the tip of an arm 519. Detection of the surface shape of the workpiece OB is performed in a predetermined plane including the rotation axis. The head drive mechanism 516 has a Z-axis guide means 517 that guides the optical pen 120 at the tip of the arm 519 along the Z-axis (e.g., the XYZ mechanical coordinate system (MCS) of the measuring device 510) parallel to the rotation axis, and an R-axis guide means 518 which is a diametrical line passing through the rotation axis that guides the optical pen 120 at the tip of the arm 519 along the R-axis. The optical pen 120 is moved in direction DR to approach the workpiece OB so that the surface of the object falls within the measurement range R' of the optical pen 120 (for example, as previously mentioned with respect to Figures 1 to 4B, the surface of workpiece OB may correspond to surface 190' in Figure 1). In various implementations, the position of the optical pen 120 can be adjusted so that variations in the surface position of the object (e.g., variations due to the rotation of the object) fall within the measurement range R' of the optical pen 120. For example, such adjustments may be determined or performed in a setup step in which the object is rotated while receiving a measurement signal from the optical pen 120, and the positions of the optical pen 120 and / or the workpiece are adjusted accordingly. In certain embodiments, the adjustment may be made so that the center of the measurement range R' is approximately located at the center of the variation in surface position.

[0040] The control processing unit 512 includes a display 520 for displaying various data, a keyboard 521 for the user to input various information, and a printer 522 for printing data as needed. The control processing unit 512 also includes a CPU 523 that controls the operation of the rotary stage 514 and the head drive mechanism 516 and processes the obtained position data through calculations, as shown in Figure 5B. The CPU 523 outputs a rotary stage drive command, which is supplied to the first motor drive circuit 524 to drive the motor 525. The driving force of the motor 525 is transmitted to the drive shaft of the rotary stage 514 via the drive force transmission mechanism 526. The rotation angle of the rotary stage 514 is detected by the rotary encoder 527, and a rotation angle signal (for example, in the form of a digital signal) corresponding to the detected rotation angle is supplied to the CPU 523.

[0041] In various implementation configurations, the CPU 523 adjusts the position of the optical pen 120. When a Z-axis drive command from the CPU 523 is supplied to the second motor drive circuit 528, a movement mechanism (e.g., a pulse motor (not shown)) incorporated in the Z-axis guide means 517 is activated. The driving force of the movement mechanism drives the optical pen 120 along the Z-axis, and the optical pen 120 is positioned. When an R-axis drive command from the CPU 523 is supplied to the third motor drive circuit 529, a movement mechanism (e.g., a pulse motor (not shown)) incorporated in the R-axis guide means 518 is activated. The driving force of the movement mechanism drives the optical pen 120 along the R-axis, and the optical pen 120 is positioned.

[0042] The MVP1 mobile unit includes a rotary stage 514, a motor 525, a drive force transmission mechanism 526, and a rotary encoder 527. In various implementations, the MVP1 mobile unit is used to move the workpiece OB (for example, relative to the optical pen 120). In various implementations, the MVP2 mobile unit has a head drive mechanism 516 and an arm 519. In various implementations, the MVP2 mobile unit is used to move the optical pen (for example, relative to the workpiece OB). In various implementations, the MCP mobile unit has a motor drive circuit 524, a motor drive circuit 528, and a motor drive circuit 529. In various implementations, the MCP mobile unit is used to perform relative movement between the optical pen 120 and the workpiece OB (for example, by controlling the MVP1 mobile unit for moving the workpiece OB and / or the MVP2 mobile unit for moving the optical pen 120). As will be explained in more detail below, the optical pen 120 is connected to the arm portion 519 by an optical pen movement structure 540, which includes a movement structure holding portion 546 and a top portion 556.

[0043] The CPU 523 receives a measurement signal (e.g., in the form of a digital signal) from the optical pen 120 via the optical pen electronics unit 160. In various implementations, an optical fiber (e.g., an optical fiber cable 112) connects the optical pen 120 to the optical pen electronics unit 160. The measurement signal received from the optical pen electronics unit 160 is stored in the memory circuit 531 along with the rotation angle signal from the rotary encoder 527. The two signals (e.g., digital signals) constitute position data relating to the surface morphology. In various implementations, the stored position data is input to the CPU 523. In various implementations, the CPU 523 can calculate the mean circle according to a known method of least squares or minimum area (zone). Roundness and coaxiality may be calculated based on the calculated mean circle. The calculation results may be displayed on the display 520, output via the printer 522, or transmitted externally via a communication line and / or wireless (not shown).

[0044] Several exemplary standard measurement operations of the measuring device may be performed as follows (for example, in this example, a cylinder is used as a workpiece OB having a bottom H1B around a rotation axis and a hole OBH1 having continuous outer and inner surfaces). The central axis of the workpiece OB may be manually or automatically aligned with the rotation axis of the rotation stage 514 in the first step (for example, by utilizing an adjustment mechanism to adjust the position of the workpiece OB on the rotation stage 514). In the second step, the operator programs the movement path 535 of the optical pen 120 (see Figure 5B) via the keyboard 521. Care must be taken to ensure that the optical pen 120 does not collide with the workpiece OB. As part of the movement path, the optical pen 120 is moved to measurement points A and B in the third and fourth steps to obtain positional data for measurement points A and B (defined, for example, on the outer surface of the workpiece OB). In the fifth step, the optical pen 120 is moved to the measurement point C to obtain positional data relating to the roundness at measurement point C, which is defined on the inner surface of the workpiece OB (for example, within the hole OBH1 in the workpiece OB). For measurement, the coordinates (R, Z) of measurement points A, B, and C may be given as the coordinates of the ideal surface of the workpiece OB. Finally, in the sixth step, the mean circle can be calculated for each of measurement points A, B, and C based on the obtained positional data using the least squares or least area method. Based on the obtained mean circle, the coaxiality and concentricity of the workpiece OB can be calculated. In various mounting configurations, the positional data for the outer and inner surfaces may be displayed with both the diameters of the surfaces aligned with each other, so that variations in the concentricity of the inner and outer surfaces as well as the thickness of the surface walls may be observed.

[0045] Position data is acquired for each measurement point A, B, and C in the same manner. First, the CPU 523 drives the optical pen 120 to each measurement point along a programmed movement path. Then, the CPU 523 rotates the rotating stage 514 at a constant speed. The rotation angle of the rotating stage 514 is detected by the rotary encoder 527 and input to the CPU 523 as a rotation angle signal at regular intervals. The optical pen 120 outputs a measurement signal to the CPU 523 each time it outputs an input rotation angle signal. The CPU 523 stores the rotation angle signal and the measurement signal as position data in the memory circuit 531. This process is performed for measurement point A, and then repeated for measurement point B and measurement point C.

[0046] Those skilled in the art will understand that the control processing unit 512 and / or CPU 523, etc., can generally be implemented using any suitable computing system or device, including a distributed computing environment or a network computing environment. Such a computing system or device may include one or more general-purpose or dedicated processors (e.g., non-custom or custom devices) that run software to perform the functions described herein. The software may be stored in memory (e.g., storage circuit 531), such as random access memory (RAM), read-only memory (ROM), flash memory, etc., or a combination of such components. The software may also be stored in one or more storage devices, such as optical-based disks, flash memory devices, or any other type of non-volatile storage medium for storing data. The software may include one or more program modules, including routines, programs, objects, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In a distributed computing environment, the functions of the program modules may be combined or distributed across multiple computing systems or devices, either in a wired or wireless configuration, and accessed via service calls.

[0047] Figure 5C shows a workpiece OB having a relatively narrow hole OBH2 measured by the measuring system 500 of Figure 5A. It will be understood that in order to measure such a narrow diameter hole OBH2, the optical pen 120 needs to have a diameter DI1 small enough to fit within the relatively small diameter DI2 of the hole OBH2. ​​As will be explained in more detail below, one problem with measuring such a relatively small diameter hole is that it can be relatively difficult (for example, for the user or measuring device, etc.) to grasp or visually locate the exact bottom of a relatively small diameter hole (for example, it can be difficult to detect how deep the small diameter hole is). On the other hand, it may be desirable to insert the optical pen 120 as far down as possible (for example, to measure near or at the bottom H2B of the small diameter hole OBH2). Due to these factors, there is an increased possibility or concern that the tip of the optical pen 120 may collide with the bottom H2B of the small diameter hole OBH2 (for example, when lowering the optical pen 120 into the small diameter hole OBH2). This can be particularly noticeable in applications where it is desirable for the inspection process to be performed relatively quickly (for example, in applications where the optical pen 120 may move relatively quickly, such as when being inserted into hole OBH2). Note that similar collisions can occur between the tip of the optical pen 120 and the bottom H1B of hole OBH1, as illustrated and described above with respect to Figure 5B.

[0048] As will be described in more detail below with respect to Figures 6 to 10, the measurement system 500 according to an exemplary embodiment has an optical pen movement structure 540 configured to allow the optical pen 120 to move from a standby position RP (see, for example, Figures 7 and 9A) when a corresponding force is applied by the optical pen 120 coming into contact with (e.g., colliding with) a workpiece OB or another object. As described herein, such contact (e.g., colliding with) may result from the movement of the optical pen 120 by the measuring instrument 510, for example, movement using the movement control unit MCP, which may cause the optical pen 120 to come into contact with (e.g., collide with) a workpiece OB or another object, for example, the optical pen 120 may come into contact with (e.g., collide with) the bottom H1B or bottom H2B of a hole OBH1 or hole OBH2 in the workpiece OB.

[0049] Thus, the optical pen movement structure 540 is useful, for example, for collision protection (to reduce or eliminate potential damage to the optical pen 120, for example, caused by a collision between the optical pen 120 and the workpiece OB or other object). As described herein, without the optical pen movement structure 540, such contact could be more likely to cause damage to the optical pen 120 (which may have relatively expensive and fragile parts). Furthermore, such collisions could have adverse effects on the structure, alignment, and / or calibration of the CRS system 100, the optical pen 120, and / or the measuring device 510.

[0050] In some conventional systems, the probe or stylus is typically mounted without displaceability (compliance) to move in the positive axial direction from its standby position RP when contact occurs (e.g., as a result of collision with a workpiece or other object). In some such conventional systems, the stylus is mounted in a “breakaway” structure, which allows the stylus to simply break away and fall away from the measuring device / probe toward the stage or ground, which may damage the optical pen 120 if a similar configuration is used. In contrast, the optical pen movement structure 540 described herein does not allow the optical pen 120 to break away and fall from the measuring device, and it should be noted that at least a portion of the optical pen 120 remains within the opening 547 of the holding portion 546 (for example, even if the optical pen 120 begins to tilt, it will continue to be supported by the holding portion 546, supported by the edge of the opening 547).

[0051] As an example of the type of use in which the optical pen movement structure 540 described herein may be particularly beneficial, in a certain application the optical pen 120 may be used to measure the inner surface / diameter of a relatively small diameter hole (as described above with respect to, for example, Figure 5C). As stated above, in such an application the optical pen needs to be small enough in diameter to fit into a relatively small diameter hole. Due to such requirements and the corresponding small dimensions, the optical pen 120 may have a relatively thin casing and other reduced-dimension structures, such configurations may be more fragile or otherwise susceptible to damage (e.g., deformation, etc.) when contact occurs (e.g., due to collision). In addition, with such relatively small diameter holes, it may be relatively difficult (e.g., for the user or measuring device) to know / see the exact bottom of the small diameter hole (e.g., to be able to detect how deep the small diameter hole is), while it may be desirable to insert the optical pen 120 as far down as possible (e.g., to perform measurements near or at the bottom of the small diameter hole). Furthermore, depending on the orientation of the measurement beam 196' (for example, at a 90-degree angle, i.e., directed to the side), the optical pen 120 may not be able to sense the bottom of the hole (e.g., H1B or H2B) (even when, for example, the tip of the optical pen 120 is approaching the bottom of the hole).

[0052] These factors may increase the likelihood of collision (for example, the optical pen 120 may descend into a small diameter hole, and the tip of the optical pen 120 may collide with the bottom of the hole). This can be particularly noticeable in applications where it is desirable for the inspection process to be performed relatively quickly (e.g., the corresponding rapid movement of the optical pen 120). In the event of such contact / collision, the optical pen movement structure 540 described herein allows the optical pen 120 to move from a standby position in the positive axial direction (e.g., relative to the arm 519 of the measuring device 510) to reduce / minimize the possibility of damage to the optical pen 120. In addition, during normal measurement operations, the optical pen movement structure 540 maintains the optical pen 120 in the desired precise position and orientation (e.g., relative to the arm 519 of the measuring device 510), ensuring conditions useful / necessary for high-precision measurement operations performed using the optical pen 120, as described herein.

[0053] With respect to the measurement operation, as described above in relation to Figures 5A and 5B, the measuring device 510 can adjust the relative position between the optical pen 120 and the workpiece OB by moving the optical pen 120 and / or the workpiece OB (for example, by using the movement control unit MCP) (for example, to enable / use the optical pen 120 to scan or measure the surface / shape of the workpiece OB, such as the surface, diameter, and holes in the workpiece). As described herein, the optical pen movement structure 540 may be configured such that the optical pen 120 is positioned at the standby position RP (for example, relative to the movement structure holder 546, the arm 519, or other reference part of the optical pen movement structure 540 or the measuring device 510, etc.) if no corresponding force sufficient to move the optical pen 120 from the standby position RP is applied to the workpiece OB or other object (for example, the stage 514, etc.) by contact (for example, contact, etc.).

[0054] More specifically, as will be described later, as part of the optical pen moving structure 540, the top portion 556 (which may be referred to as the same as or alternatively as the “cap portion” in some implementations) is fixedly attached to the optical pen 120, and the moving structure holding portion 546 (which may be referred to as the “base portion” in certain embodiments) is fixedly attached to the measuring device 510 (e.g., the arm portion 519 of the measuring device). In various implementations, the top portion 556 is connected to the moving structure holding portion 546 by a kinematic coupling structure KN1 (i.e., the optical pen 120 is connected to the measuring device 510), and the optical pen 120 is in a standby position RP. When contact (for example, equivalent to a collision) occurs, the optical pen 120 is pushed upward, and as a result, the top portion 556 (fixed to the optical pen 120) separates from the movable structure holder portion 546, thereby allowing the optical pen 120 to continue moving upward (for example, away from the standby position) without resistance, thus preventing or reducing damage to the optical pen 120 that could otherwise occur due to a collision. If the optical pen movable structure 540 is not provided (for example, if the optical pen 120 is rigidly connected to or attached to a measuring device and upward movement of the optical pen 120 is impossible and / or is hindered by components above the optical pen 120), it will be understood that the risk of damage to the optical pen 120 in the event of contact such as a collision will increase accordingly.

[0055] Figure 6 is an isometric view of a chromatic range sensor optical pen 120 connected to (for example, rigidly mounted) the top portion 556 of the optical pen moving structure 540. Figure 7 is a partial cross-sectional side view of a part of the optical pen moving structure 540. Figure 8 is an isometric view of the top portion 556 with respect to the moving structure holding portion 546 of the optical pen moving structure. Figures 9A and 9B are isometric views of the end of the arm portion 519 of the measuring device 510 (for example, Figures 5A and 5B), to which the moving structure holding portion 546 is rigidly mounted and the top portion 556 is connected to it (see Figure 9A) and separated from it (see Figure 9B).

[0056] As shown in Figures 6 to 9B (e.g., in particular Figures 6, 7 and 9A), the optical pen movement structure 540 is configured to allow the optical pen 120 to move from a standby position RP (see Figure 7, for example, showing an exemplary reference position RP) to a positive axial position PAD (e.g., a move relative to the movement structure holder 546) when a corresponding force in the positive axial direction PAD is applied by contact (e.g., such contact may occur with respect to the workpiece OB, stage 514, or other object, as shown in Figures 5B and 5C). The optical pen movement structure 540 is also configured to allow the optical pen 120 to move from a standby position RP in the vertical direction PRD (e.g., perpendicular to the positive axial position PAD, see Figures 6 and 7) (e.g., allowing the movement of the tip of the optical pen 120) when a corresponding force in the vertical direction PRD is applied by contact (e.g., such contact may occur with respect to the workpiece OB, stage 514, or other object, as shown in Figures 5A and 5B).

[0057] In various implementations, an arbitrary reference point on the optical pen 120 (for example, near the proximal end of the optical pen 120, or near the tip of the optical pen 120, or another location, as shown in the example in Figure 7) may be used to indicate when the optical pen is in a standby position (for example, the current coordinates of the reference point may be the coordinates of the corresponding reference position, or different from the coordinates of the corresponding reference position) or when it is moving from the standby position. Similarly, an arbitrary reference point on any other component of the optical pen movement structure 540 may be used to indicate when that component is in its standby position or when it has moved from the standby position (for example, the current coordinates of the reference point may be the coordinates of the corresponding reference position, or different from the coordinates of the corresponding reference position). In various implementations, the coordinates of the standby position (e.g., standby position RP) may be defined within a coordinate system that may be related to a part of the movement structure holder 546, or to other reference parts of the optical pen movement structure 540 and / or measuring device 510 (e.g., on the arm 519), etc.

[0058] In the example in Figure 7, the standby position RP is shown along the central axis directly above the movable structure holder 546 (i.e., at a constant position relative to the movable structure holder 546). In this example, if the reference point (i.e., not shown but fixed on the optical pen 120 and at the same position as the reference position RP in Figure 7) moves away from the reference position RP / is not at the reference position RP (for example, when the top part 556 moves away from the movable structure holder 546 or otherwise moves relative to it), this corresponds to the movement of the optical pen 120 from the standby position RP. As described above, similar reference points and standby positions may be specified for other components (for example, when the reference point on the top part 556 moves on the movable structure holder 546 or a standby position associated therewith).

[0059] In various implementations, the optical pen movement structure 540 is further configured as follows: when the optical pen 120 is moved / moved in the opposite direction to the negative axial direction NAD and / or the vertical direction PRD (e.g., by gravity or by the user), the optical pen 120 is configured to return to the standby position RP when the optical pen 120 is separated from the workpiece OB or other object it has come into contact with (i.e., when contact is resolved). In various implementations, the positive axial direction PAD and the negative axial direction NAD may be generally parallel to the Z-axis, and the vertical direction PRD may be generally located in the XY plane (with respect to a local coordinate system (LCS), such as shown in Figure 1). In various implementations, as will be described in more detail below, a specific force (e.g., gravity) and / or a holding configuration (e.g., including a magnet) acts as a force to hold the optical pen 120 in the standby position RP (i.e., to maintain it in the standby position RP under normal measurement operating conditions) and can act until contact (e.g., contact equivalent to a collision) occurs. According to the principles described herein, it may be desirable that the components be configured such that any such force is sufficiently small so that the optical pen 120 can move upward (e.g., away from its standby position) when contact occurs (e.g., in response to a collision) without causing damage to the optical pen 120.

[0060] In various configurations, the top portion 556 has a pen connector portion PCP (see, for example, Figure 8) configured to be rigidly connected to and / or otherwise rigidly attached to the optical pen 120, specifically to the mounting portion ATP of the optical pen (see, for example, Figure 7). In various configurations, the pen connector portion PCP may include a hole having a fixing element or other configuration for receiving and fixedly holding the mounting portion ATP of the optical pen 120. Various types of such connector configurations are known in the art.

[0061] In various implementations, the optical pen 120 is configured to be located at the standby position RP (relative to the moving structure holder 546 or other reference part) when no corresponding force is applied to the optical pen 120 (i.e., the non-contact sensor) that is sufficient to move it from the standby position RP due to contact with the workpiece OB or other object (e.g., the stage 514, etc.) (e.g., corresponding to a collision). In some examples, the standby position RP is defined in relation to a reference point (not shown) near the proximal end of the optical pen 120, and when the optical pen moves in the positive axial direction PAD and / or vertical direction PRD (i.e., relative to a part of the measuring device 510 such as the moving structure holder 546 and / or the arm 519) (e.g., when the tip of the optical pen 120 is moved), the reference point (of the optical pen 120) is no longer located at the corresponding standby position RP. With respect to the local coordinate system (LCS) shown in Figure 1, the movement in the positive axis direction PAD and the negative axis direction NAD generally represents movement primarily parallel to the Z axis, while the movement in the vertical direction PRD generally represents movement in the X axis and / or Y axis directions.

[0062] In various implementations, as partially shown in Figures 7, 8, 9A, and 9B, the optical pen movement structure 540 has a kinematic coupling structure KN1, and the top portion 556 is connected to the movement structure holding portion 546 as part of the kinematic coupling structure KN1. Such kinematic coupling structures are generally designed to precisely restrain two interlocking parts, providing precision and positioning reliability. One form of the kinematic coupling structure is the Maxwell-type kinematic coupling structure, which can be used for the kinematic coupling structure KN1 in various implementations. Such a Maxwell-type kinematic coupling structure has three radial V-shaped grooves (oriented relative to the center of the part) within a single part that mate with three curved surfaces (e.g., balls, hemispheres, spherical portions). Each curved surface has two contact points to a total of six contact points, sufficient to restrain all six degrees of freedom of the part when mate with the V-shaped grooves. This design has the advantage of being symmetrical, allowing for the use of simpler manufacturing techniques. Furthermore, the Maxwell-type joint is thermally stable due to its symmetry, because the curved surfaces can expand or contract simultaneously within the V-shaped groove.

[0063] In various implementations, the kinematic coupling structure KN1 (e.g., Maxwell-type kinematic coupling structure) includes a set of three radial V-shaped grooves 548 (see Figures 7 and 8) arranged at 120-degree intervals in the circumferential direction in one part (e.g., top part 556) and a set of three curved surfaces 558 (e.g., the surfaces of each ball) arranged at 120-degree intervals in the circumferential direction in the other part (e.g., movable structure holder part 546), where the three V-shaped grooves 548 engage with the three curved surfaces 558. In the example of Figure 8, the movable structure holder part 546 has three curved surfaces 558, while the top part 556 has more than three radial V-shaped grooves 548 that engage with the three curved surfaces 558. In various implementations, additional radial V-grooves 548 may be provided to allow the measuring beam 196' of the optical pen 120 (see, for example, Figures 1 and 6) to be directed in different directions for different measurement operations. More specifically, in the example of Figure 8, the top portion 556 is shown to include / have 12 radial V-grooves 548 arranged at 30-degree intervals in the circumferential direction. With this configuration, once the optical pen 120 is fixedly attached to the top portion 556, the top portion 556 can be connected to the movable structure holder 546 in different orientations (for example, rotated 30 degrees relative to each other with the measuring beams 196' correspondingly directed in different directions).

[0064] During assembly / connection, the curved surface 558 of the ball rests within the corresponding V-shaped groove 548 of the top portion 556. In various mounting configurations, if contact occurs with the vertical PRD (e.g., the vertical PRD shown in Figures 6 and 7) (e.g., the tip of the optical pen 120), resulting in movement in the X-axis and / or Y-axis directions, the top portion 556 may tilt / rotate relative to the holding portion 546. For example, one or two of the V-shaped grooves 548 of the kinematic coupling structure KN1 may be tilted upward away from the corresponding curved surface 558, while the other one or two V-shaped grooves 548 may function as pivot points while maintaining contact with the corresponding curved surface 558.

[0065] According to the exemplary configuration and assembly described above, the kinematic coupling structure KN1 achieves high positional repeatability of the top portion 556 (and therefore the optical pen 120) relative to the movable structure holder portion 546. Such characteristics are desirable in high-precision measurement systems configured to perform measurements on the order of microns or submicrons. In some such implementations, the optical pen 120 may have characteristics such that high positional repeatability is relevant to high-precision measurement. For example, the optical pen 120 may have certain characteristics that can be addressed by calibration or other techniques, and such addressing may be at least partially based on the angular direction or other orientation of the optical pen 120. In general, high positional repeatability for the optical pen 120 helps ensure high-precision measurement of the system.

[0066] In various implementations, a retaining configuration (including, for example, retaining members 562 and 563) may be used to provide a retaining force to hold the top portion 556 in a fixed position relative to the movable structure retaining portion 546 (for example, during normal measurement operation). In the example in Figure 8, retaining member 562 (e.g., a magnet) is shown on the movable structure retaining portion 546, and retaining member 563 (e.g., a magnet) is shown on the top portion 556. Retaining members 562 and 563 provide an attractive retaining force to each other, thereby helping to hold the top portion 556 in a fixed position and orientation relative to the movable structure retaining portion 546.

[0067] According to the principles described herein, in various implementations, the retaining members 562 and 563 may be configured such that the “separation” force (i.e., the force required to separate retaining member 562 from retaining member 563) is small enough to allow the optical pen 120 (i.e., the force required to separate retaining member 562 and retaining member 563) to move upward without being damaged when contact (e.g., contact corresponding to a collision) occurs. In the example of Figure 8, the top section 556 has 12 retaining members 563 arranged in 30-degree increments (similar to, for example, 12 radial V-shaped grooves 548), and the moving structure retaining section 546 has 6 retaining members 562 arranged in 60-degree increments. This corresponds to a total of 6 pairs of retaining members that generate tensile retaining force, but it will be understood that in alternative configurations, there may be more (e.g., 12) or fewer (e.g., 3) pairs of retaining members to provide tensile retaining force. It will be understood that such a retaining configuration can be used to provide distributed and balanced attractive forces between kinematic components, regardless of the orientation of the rotational mounting.

[0068] In various implementations, the optical pen 120 is configured to be connected to a measurement system and is oriented so that the optical axis OA of the optical pen 120 (see, for example, Figure 1) is parallel to the z-axis of the measurement system (as shown, for example, Figure 5B). In various implementations, the optical pen 120 is configured to be moved downward by the measurement system 500 (for example, by utilizing at least a part of the movement control unit MCP, such as the drive circuit 528, to control the movement part, such as the movement part 517). In some situations, such downward movement may cause the optical pen 120 to come into contact with (e.g., collide with) a workpiece OB or another object (e.g., the stage 514). This imparts a positive axial force PAD to the optical pen 120, enabling the optical pen movement structure 540 (for example, with respect to the movement structure holder 546 and the arm 519 of the measuring device 510, etc.) to move the optical pen 120 from the standby position RP to the positive axial force PAD.

[0069] As shown in Figures 7, 8, and 9B, the movable structure holder 546 includes an opening 547 (e.g., a hole) into which at least a portion of the optical pen 120 extends downward when the top portion 556 is connected to the movable structure holder 546. In various mounting configurations, at least a portion of the optical pen 120 moves upward within the opening 547 when a corresponding force is applied by the optical pen 120 contacting a workpiece or other object (e.g., to correspond to a collision), and the optical pen 120 moves from the standby position RP in the positive axial direction. In various mounting configurations, at least a portion of the opening 547 (e.g., the tip of the opening) is formed with a diameter at least 10% or at least 25% larger than the diameter of the optical pen 120 (specifically, this is to allow the tip of the optical pen 120 to move in the orthogonal direction PRD, which is perpendicular to the positive axial direction PAD, thereby allowing the optical pen 120 to move from the standby position when an orthogonal force is applied by contact with a workpiece or other object).

[0070] For example, as shown in Figure 7, the opening 547 is a conical hole (for example, the lower diameter is larger than the upper diameter, so that when there is contact with the vertical PRD, the tip of the optical pen 120 moves in the X and / or Y directions and the optical pen 120 tilts). In various implementations, the optical pen movement structure 540 is configured such that, as part of the replacement process, the optical pen 120 slides upward through the opening 547, and the replacement optical pen slides downward through the opening 547 until the top portion 556 fixedly attached to the replacement optical pen (for example, the same top portion 556 or a different top portion 556) is connected to the movement structure holding portion 546, thereby placing the replacement optical pen in the standby position RP.

[0071] Figure 10 is a flowchart showing one embodiment of a general routine 1000 for operating a measurement system including an optical pen movement structure. In block 1010, a measurement system is provided, which includes: a chromatic range sensor system having a chromatic range sensor (CRS) optical pen configured to focus different wavelengths at different distances in close proximity to the surface of a workpiece to be measured; a measuring device to which the CRS optical pen is connected; and an optical pen movement structure. In block 1020, the measuring device is used to adjust the relative position between the CRS optical pen and the workpiece to be measured. In block 1030, the optical pen movement structure allows the CRS optical pen to move from a standby position in the positive axial direction when a corresponding force in the positive axial direction is applied by the CRS optical pen coming into contact with (e.g., corresponding to a collision) the workpiece or another object.

[0072] In the following, various exemplary embodiments relating to this specification will be described using the features and components indicated by the reference numerals in Figures 1 to 10. The reference numerals are provided to indicate exemplary embodiments, and it should be understood that the features and components are not limited to the specific embodiments illustrated in Figures 1 to 10.

[0073] As described herein, a measurement system 500 is provided, comprising a chromatic range sensor optical pen 120, a measuring device 510, and an optical pen moving structure 540. The optical pen 120 focuses different wavelengths at different distances in the vicinity of the workpiece OB to be measured. The measuring device 510 adjusts the relative position of the optical pen 120 and the workpiece OB (for example, to utilize the optical pen to measure the workpiece). The optical pen moving structure 540 is connected to (for example, fixedly mounted to) the optical pen 120 and has a top portion 556, which is configured to move in a positive axial direction PAD (relative to a holding portion 546 attached to the measuring device 510, such as being attached to the arm portion 519 of the measuring device). This makes the optical pen 120 movable from a standby position RP when a corresponding force is applied to the positive axial direction PAD by the optical pen 120 coming into contact with the workpiece OB or another object (for example, to respond to a collision) (thus minimizing, for example, potential damage to the optical pen 120).

[0074] In various implementations, the top portion 556 (e.g., fixedly attached to the optical pen 120) is connected to a movable structure holder 546 (e.g., fixedly attached to a measuring device) as part of a kinematic coupling structure KN1. In various implementations, the top portion 556 is further configured to tilt (e.g., in accordance with the movement of the kinematic coupling structure KN1) to allow movement of the tip of the optical pen 120 in a vertical PRD perpendicular to the positive axial direction PAD, when a corresponding force in the vertical PRD is applied by contact with a workpiece OB or other object (e.g., in response to a collision), causing the optical pen 120 to move from the standby position RP. In various implementations, the top portion 556 includes a pen coupling portion PCP configured to be securely attached to the mounting portion ATP of the optical pen.

[0075] As described above, in various implementations, the optical pen movement structure 540 includes a kinematic coupling structure KN1. In various implementations, the kinematic coupling structure KN1 is configured to separate into positive axial PAD when a corresponding force in the positive axial direction is applied by contact (e.g., collision) between the optical pen 120 and a workpiece OB or other object. In various implementations, the kinematic coupling configuration includes a set of radially V-shaped grooves 548 located in one part of the optical pen movement configuration (e.g., the top part 556) and a set of three curved surfaces 558 located at 120-degree intervals in the circumferential direction in the other part of the optical pen movement structure 540 (e.g., the holding part 546), which are configured to fit together.

[0076] In various implementations, as part of adjusting the relative position between the optical pen 120 and the workpiece OB (for example, to use the optical pen 120 to measure the workpiece OB), the measuring device 510 is configured to move the optical pen 120 downward, which may cause contact (e.g., collision) with the workpiece OB or other object, resulting in a positive axial force PAD on the optical pen. In such a situation, the optical pen moving structure 540 enables the movement of the optical pen 120 from the standby position RP to the positive axial force PAD. In various implementations, the movement of the optical pen 120 from the standby position RP corresponds to the movement of the optical pen 120 relative to the moving structure holding part 546 of the optical pen moving structure 540.

[0077] As described above, in various implementations, the optical pen movement structure 540 has a movement structure holder 546 connected to (e.g., fixedly mounted) a measuring device and a top part 556 connected to (e.g., fixedly mounted) the optical pen 120, the top part 556 being configured to move relative to the movement structure holder 546 (e.g., according to a kinematic coupling structure KN1), thereby allowing the optical pen 120 to move from the standby position RP in response to the force applied when the optical pen 120 comes into contact with (e.g., corresponding to a collision) a workpiece OB or another object. In various implementations, the optical pen movement structure 540 further includes an optical pen holding configuration having one or more holding members 562, holding members 563 configured to provide a holding force for holding the top part 556 in a fixed position relative to the movement structure holder 546. In various implementations, each of the one or more holding members has a magnet.

[0078] In various implementations, the movable structure holder includes an opening 547 (e.g., a hole) through which at least a portion of the optical pen 120 passes and extends downward when the top portion 556 is connected to the movable structure holder 546 (e.g., according to a kinematic coupling structure KN1). In various implementations, at least a portion of the optical pen 120 moves upward within the opening 547 when a corresponding force is applied by contact of the optical pen 120 with a workpiece OB or other object in the positive axial direction PAD (e.g., corresponding to a collision) and the optical pen 120 moves from the standby position RP. In various implementations, at least a portion of the opening 547 (e.g., the tip of the opening) has a diameter at least 25% larger than the diameter of the optical pen 120 in the vertical PRD perpendicular to the positive axial direction PAD, thereby moving the optical pen 120 from the standby position RP when a corresponding force in the vertical PRD is applied by contact with a workpiece OB or other object (e.g., corresponding to a collision).

[0079] In various implementations, the optical pen movement structure 540 is configured such that, as part of the replacement process, the optical pen 120 slides upward through the opening 547 to be removed, and a replacement optical pen slides downward through the opening 547 and is inserted until the top portion 556 connected to the replacement optical pen is connected to the movement structure holding portion 546 (for example, as part of a kinematic coupling structure KN1), and as a result the replacement optical pen is placed in the standby position RP. In various implementations, it will be understood that the optical pen movement structure 540 and the measuring device 510 do not include any fixed components or structures above the top portion 556 that would obstruct or resist the upward movement of the top portion 556. For example, when removing the optical pen 120 as part of the replacement process, and / or when the top portion 556 moves upward due to contact such as a collision between the optical pen 120 and the workpiece OB or other object, there is no configuration that would obstruct or resist such movement.

[0080] As described above, in various implementations, the optical pen movement structure 540 is provided for use in a measurement system. The optical pen movement structure comprises a movement structure holder 546 and a top portion 556. The top portion 556 is configured to be connected to (e.g., fixedly attached to) the optical pen 120. The top portion 556 is connected to the movement structure holder 546 as part of a kinematic coupling structure KN1. The top portion 556 is configured to separate from the movement structure holder 546 (e.g., according to the operation of the kinematic coupling structure KN1) so that when a corresponding force in the positive axial direction is applied due to contact (e.g., collision) between the optical pen 120 and a workpiece OB or other object, the optical pen 120 can move from a standby position RP to a positive axial direction PAD.

[0081] While preferred implementations of the Disclosure have been illustrated and described, numerous variations in the illustrated and described configurations and sequences of operation of the features will be apparent to those skilled in the art based on this Disclosure. Various alternative configurations may be used to carry out the principles disclosed herein. In addition, the various implementations described above can be combined to provide further implementations. All U.S. patents and U.S. patent applications referenced herein are incorporated herein by reference in their entirety. The aspects of the embodiments can be modified, as needed, to employ concepts from various patents and applications to provide further embodiments.

[0082] In light of the detailed description above, these and other modifications may be applied to the implementations. In general, the terms used in the following claims should not be construed as limiting the claims to the specific implementations disclosed herein and herein, but rather as encompassing all possible implementations along with the entire range of equivalents to which rights are granted.

Claims

1. A chromatic range sensor system having a chromatic range sensor optical pen configured to focus different wavelengths at different distances in close proximity to the surface of the workpiece being measured, A measuring device configured such that the optical pen is connected to the measuring device in a standby position, and the measuring device is configured to adjust the relative position between the optical pen and the workpiece to be measured, An optical pen movement structure configured to enable the movement of the optical pen from a standby position when a corresponding force is applied by the optical pen coming into contact with the workpiece or other object, wherein the optical pen movement structure has a top portion configured to be connected to the optical pen and configured to move in the positive axial direction when a corresponding force in the positive axial direction is applied by the optical pen coming into contact with the workpiece or other object, A measurement system equipped with the following features.

2. The optical pen movement structure further includes a movement structure holding part, The aforementioned top portion is connected to the movable structure holding portion as part of the kinematic coupling structure. The system according to claim 1.

3. The top portion is inclined to allow vertical movement of the tip of the optical pen perpendicular to the positive axis, and is further configured so that the optical pen moves from the standby position when a corresponding vertical force is applied by contact with the workpiece or other object. The system according to claim 1.

4. The top portion has a pen connecting portion configured to be rigidly attached to the mounting portion of the optical pen. The system according to claim 1.

5. The optical pen movement structure includes a kinematic coupling structure. The system according to claim 1.

6. The kinematic coupling structure is, The optical pen is configured to separate in the positive axial direction when a corresponding force in the positive axial direction is applied by contact with the workpiece or other object. The system according to claim 5.

7. The kinematic coupling structure is, The optical pen movement structure has a collection of radially V-shaped grooves arranged in a part thereof, The multiple V-shaped grooves engage with a set of three curved surfaces arranged at 120-degree intervals in the circumferential direction in another part of the optical pen movement structure. The system according to claim 5.

8. The measuring device is configured to move the optical pen downward as part of adjusting the relative position between the optical pen and the workpiece, thereby causing contact with the workpiece or other object and applying a positive axial force to the optical pen. The optical pen movement structure enables the optical pen to move from the standby position in the positive axial direction in response to the force. The system according to claim 1.

9. The movement of the optical pen from the standby position corresponds to the movement of the optical pen relative to the movement structure holding part of the optical pen movement structure. The system according to claim 1.

10. The optical pen movement structure further includes a movement structure holding part, The top portion connected to the optical pen is configured to move relative to the movable structure holding portion, thereby allowing the optical pen to move from the standby position when a corresponding force is applied by the optical pen coming into contact with the workpiece or other object. The system according to claim 1.

11. The optical pen movement structure further includes an optical pen holding structure having one or more holding members, The holding member is configured to provide a holding force that holds the top portion in a fixed position relative to the movable structure holding portion. The system according to claim 10.

12. Each of the one or more retaining members includes a magnet. The system according to claim 11.

13. The movable structure holding portion includes an opening through which at least a portion of the optical pen extends downward when the top portion is connected to the movable structure holding portion. The system according to claim 10.

14. At least a portion of the optical pen moves upward within the opening when the optical pen moves from its standby position, a corresponding force is applied in the positive axial direction by the optical pen contacting the workpiece or other object. The system according to claim 13.

15. At least a portion of the opening has a diameter at least 25% larger than the diameter of the optical pen, thereby allowing the tip of the optical pen to move vertically perpendicular to the positive axis, and enabling the optical pen to move from its standby position when a corresponding vertical force is applied due to contact with the workpiece or other object. The system according to claim 13.

16. The optical pen movement structure is As part of the replacement process, the optical pen is slid upward through the opening, and then the replacement optical pen is slid downward through the opening until the top portion connected to the replacement optical pen is connected to the movable structure holder, so that the replacement optical pen is in a standby position. The system according to claim 13.

17. The movable structure holding part is connected to the measuring device. The system according to claim 10.

18. A method for operating a measurement system, The aforementioned measurement system is A chromatic range sensor system having a chromatic range sensor optical pen configured to focus different wavelengths at different distances in close proximity to the surface of the workpiece being measured, A measuring device configured such that the optical pen is connected to the measuring device in a standby position, An optical pen movement structure configured to enable the movement of the optical pen from the standby position when a corresponding force is applied by the optical pen coming into contact with the workpiece or another object, the optical pen movement structure having a top portion configured to be connected to the optical pen, Equipped with, The steps include adjusting the relative position between the optical pen and the workpiece to be measured using the measuring device, The steps include using the optical pen moving structure to enable the optical pen to move from the standby position in the positive axis direction when a corresponding force in the positive axis direction is applied due to the optical pen coming into contact with the workpiece or another object, and A method for operating a measurement system, comprising the characteristics of a measurement system.

19. An optical pen movement structure used in a measurement system, The aforementioned measurement system is A chromatic range sensor system having a chromatic range sensor optical pen configured to focus different wavelengths at different distances in close proximity to the surface of the workpiece being measured, A measuring device configured such that the optical pen is connected to the measuring device in a standby position, Equipped with, The optical pen movement structure is A top part configured to be connected to the optical pen, The top portion is connected to the movable structure holder as part of a kinematic coupling structure, and the top portion is configured to separate from the movable structure holder when a corresponding force in the positive axial direction is applied by the optical pen contacting the workpiece or other object, thereby enabling the optical pen to move in the positive axial direction from the standby position. An optical pen movement structure having the following features.

20. The top portion is inclined to allow vertical movement of the tip of the optical pen perpendicular to the positive axis, and is further configured so that the optical pen moves from the standby position when a corresponding vertical force is applied by contact with the workpiece or other object. The optical pen movement structure according to claim 19.

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