Chromatic range sensor system comprising a camera

Abstract

A chromatic range sensor (CRS) system is configured to provide a focused image of a workpiece surface containing a measurement spot that can be used as a guide light. The system includes an optical pencil having a chromatic dispersion lens configuration that provides axial dispersion, and a reflected light splitting configuration (e.g., a beamsplitter) arranged to receive reflected light from the workpiece surface and split it into a measurement portion and an imaging portion. The optical pencil includes a narrowband spectral filter and a camera. The CRS system includes a processing portion configured to measure a distance from the optical pencil to the workpiece surface, and make an adjustment so that the distance corresponds to a focus distance at which the workpiece surface is in focus when imaged by light passing through the narrowband spectral filter.

Description

TECHNICAL FIELD

[0001] The present invention relates to precision measuring instruments, and more particularly to chromatic range sensors capable of providing a focused image of a surface of a workpiece to be measured containing a measurement spot formed thereon and uses thereof. BACKGROUND

[0002] It is known to use chromatic confocal technology in optical range sensors, such as height, distance, etc. sensors. As described in U.S. Patent No. 7,876,456, which is hereby incorporated by reference in its entirety, optical elements with axial chromatic aberration, also known as axial or longitudinal dispersion, can be used to focus a broadband light source such that the axial distance to the focal point varies with wavelength. Thus, only one wavelength will be precisely focused on the surface, and the surface height or distance relative to the focusing element determines which wavelength is best focused. Upon reflection from the surface, the light is refocused onto a small detector aperture, such as the end of a pinhole or optical fiber. Upon reflection from the surface and back through the optical system to the input / output fiber, only the wavelength that was well focused on the surface will be well focused on the aperture. All other wavelengths are poorly focused on the aperture and thus will not couple much power into the fiber. Thus, for the light returning through the fiber, the signal level corresponding to the wavelength of the surface height or distance to the surface will be the largest. A spectrometer type detector measures the signal level for each wavelength to determine the surface height.

[0003] Certain manufacturers refer to practical and compact chromatic range sensing (CRS) systems that operate as described above and are suitable for use in industrial environments as chromatic point sensors (CPS) or chromatic line sensors, etc. The compact chromatic dispersion optical assembly used with such systems is referred to as an "optical pen" or "pen." The optical pen is connected by an optical fiber to the electronics portion of the chromatic range sensor. The electronics portion contains a first light source that causes light to be transmitted through the optical fiber for output from the optical pen, and also provides a spectrometer that detects and analyzes the returned light. The returned light forms a wavelength-dispersed intensity profile that is received by a detector array of the spectrometer. The pixel data corresponding to the wavelength-dispersed intensity profile is analyzed to determine a "primary wavelength position coordinate" (as indicated by a peak or centroid of the intensity profile), and the resulting pixel coordinate (of the peak and / or centroid) is used with a lookup table to determine the distance to the surface. SUMMARY

[0004] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the DETAILED DESCRIPTION. This Summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used to determine the scope of the claimed subject matter.

[0005] Prior art CRS systems lack a means by which a user can readily confirm that a workpiece surface is properly positioned with respect to the CRS system so that the CRS system will measure the correct points (i.e., the distance to the correct points) of the workpiece surface. Specifically, while the CRS lens arrangement is suitable for CRS measurement operations that focus different wavelengths at different distances, for some reason it is not well suited for imaging operations. That is, different wavelengths returning to the imaging camera will be focused at different distances, thereby forming a confused image that is mostly blurry because only one of the different wavelengths will be in focus.

[0006] Various aspects of the present invention relate to configuring a CRS system to be able to provide a focused image of a workpiece surface that contains a measurement spot formed thereon. The CRS system allows a user to view the focused image of the measurement spot as "guidance light" when the workpiece surface is properly positioned with respect to the optical pen of the CRS system, thereby giving the user a more direct assurance that the CRS system is always measuring the correct points on the workpiece surface.

[0007] According to one aspect, a chromatic range sensor (CRS) system is provided that is operable to provide a focused image of a workpiece surface to be measured, wherein the image contains a measurement spot formed on the workpiece surface. The CRS system includes: (a) an optical pen; (b) a first light source; (c) a CRS wavelength detector; and (d) a processing portion.

[0008] The optical pen includes a housing; an input / output optical fiber that includes an optical fiber aperture configured to output light along a measurement light path and to receive reflected light along the measurement light path; and a chromatic dispersion lens arrangement having an optical axis that defines a measurement axis of the chromatic confocal range sensor optical pen. The lens arrangement includes in the measurement light path and is configured to: receive light and output focused light to the workpiece surface having an axial chromatic dispersion such that different wavelengths are focused at different distances proximate the workpiece surface; and receive reflected light from the workpiece surface and focus at least a portion of the reflected light along the measurement light path to a point proximate the optical fiber aperture.

[0009] The optical pen further includes a reflected light splitting arrangement arranged to receive the reflected light from the chromatic dispersion lens arrangement and to split the reflected light into a measurement portion and an imaging portion. The optical pen also includes a narrowband spectral filter arranged to filter at least a portion of the imaging portion of the reflected light; and a camera portion including an image detector configured to receive at least a portion of the imaging portion of the reflected light that passes through the narrowband spectral filter for producing a camera image.

[0010] The first light source is configured to generate a first light of multiple wavelengths that is input to the optical pen.

[0011] The CRS wavelength detector includes a plurality of pixels each pixel position distributed along a measurement axis of the CRS wavelength detector, configured to receive at least a portion of the measurement portion of the reflected light and provide output spectral profile data.

[0012] The processing portion is configured to process the output spectral profile data to measure the distance from the optical pen to the workpiece surface and make an adjustment so that the distance from the optical pen to the workpiece surface corresponds to a focus distance at which the workpiece surface is in focus when imaged by the light passing through the narrowband spectral filter, wherein the light not passing through the narrowband spectral filter includes out-of-focus light.

[0013] According to one aspect, in the CRS system, after the adjustment is made by the processing portion, the corresponding camera image includes a measurement spot on the in-focus workpiece surface, wherein the measurement spot is formed from a portion of the imaged portion of the reflected light, the reflected light including first light from the first light source that is output from the fiber aperture and reflected by the workpiece surface.

[0014] According to another aspect, the CRS system further includes a second light source that generates second light that is input to the chromatic dispersion lens configuration, wherein the imaged portion includes reflected second light that is reflected from the workpiece surface. For example, the second light source can include a light emitting diode (LED). For example, the spectral bandwidth of the narrowband spectral filter falls within the spectral bandwidth of the second light source.

[0015] According to another aspect, the narrowband spectral filter has a spectral bandwidth that is less than 10 nanometers.

[0016] According to another aspect, the narrowband spectral filter has a spectral bandwidth that is less than 5 nanometers.

[0017] According to another aspect, the spectral bandwidth of the narrowband spectral filter is similar to a spectral bandwidth of the received reflected light that is coupled back into the input / output fiber through the fiber aperture, such that the bandwidth of the narrowband spectral filter is no more than twice the spectral bandwidth that is coupled back into the fiber.

[0018] According to another aspect, the narrowband spectral filter has a center wavelength that corresponds to a middle portion of a CRS measurement range of the CRS system.

[0019] According to another aspect, the CRS system further includes a screen portion configured to display the camera image.

[0020] According to another aspect, the processing portion is operable in a plurality of modes, including a measurement mode in which the distance from the optical pen to the workpiece surface is measured based on the measurement portion of the reflected light, and a pilot light mode in which the camera image of the workpiece surface is generated based on the imaged portion of the reflected light, and for the pilot light mode, the camera image includes a measurement spot that is configured to function as a pilot light.

[0021] According to another aspect, the adjustment made by the processing portion includes causing the distance from the optical pen to the workpiece surface to correspond to the focal distance. For example, the adjustment can include adjusting the distance from the optical pen to the workpiece surface with a motion controller. For example, the motion controller can be part of a machine vision inspection system coupled with the optical pen.

[0022] According to another aspect, the reflected light splitting configuration includes a beamsplitter.

[0023] According to another aspect, the ratio of the measurement portion to the imaging portion is at least 5 to 1.

[0024] According to another aspect, at least a portion of the measurement portion of the reflected light and at least a portion of the imaging portion of the reflected light propagate parallel to each other.

[0025] According to another aspect, the measurement portion and the imaging portion of the reflected light extend along two different optical axes after being split by the reflected light splitting configuration.

[0026] According to another aspect, a method of operating a colorimetric range sensor (CRS) system to provide a focused image of a workpiece surface containing a measurement spot to be measured is provided. The CRS system includes: (a) an optical pen; (b) a first light source configured to generate a first light of multiple wavelengths input to the optical pen; and (c) a CRS wavelength detector.

[0027] The optical pen includes a housing; an input / output optical fiber including an optical fiber aperture configured to output light along a measurement optical path and receive reflected light along the measurement optical path; and a chromatic dispersion lens configuration having an optical axis defining a measurement axis of the colorimetric confocal range sensor optical pen. The lens configuration includes in the measurement optical path and is configured to: receive light and output focused light to a workpiece surface having an axial chromatic dispersion such that different wavelengths are focused at different distances proximate the workpiece surface; and receive reflected light from the workpiece surface and focus at least a portion of the reflected light along the measurement optical path to a point proximate the optical fiber aperture.

[0028] The optical pen also includes a reflected light splitting configuration arranged to receive the reflected light from the chromatic dispersion lens configuration and split the reflected light into a measurement portion and an imaging portion. The optical pen further includes a narrowband spectral filter arranged to filter at least a portion of the imaging portion of the reflected light; and a camera portion including an image detector configured to receive at least a portion of the imaging portion of the reflected light through the narrowband spectral filter for producing a camera image.

[0029] The CRS wavelength detector includes a plurality of pixels each pixel position distributed along a measurement axis of the CRS wavelength detector configured to receive at least a portion of the measurement portion of the reflected light and provide output spectral profile data.

[0030] The method includes the following steps, which include:

[0031] operating the CRS system based on the output spectral profile data to measure a distance from the optical probe to the workpiece surface;

[0032] adjusting so that the distance from the optical probe to the workpiece surface corresponds to a focus distance at which the workpiece surface is in focus when imaged by light passing through the narrowband spectral filter; and

[0033] displaying a camera image that includes the workpiece surface with the measurement spot.

[0034] According to another aspect, the method further includes the following steps:

[0035] irradiating the workpiece surface with a second light input to the chromatic dispersion lens configuration, wherein the second light includes wavelengths that fall within a spectral bandwidth of the narrowband spectral filter, and the imaged portion includes reflected second light for imaging the workpiece surface. For example, the imaged portion can further include reflected first light for imaging the measurement spot, for which the camera image includes an image of the workpiece surface and an image of the measurement spot on the workpiece surface.

[0036] According to one aspect, the narrowband spectral filter has a center wavelength that corresponds to a middle portion of a CRS measurement range of the CRS system.

[0037] According to one aspect, the method further includes the following steps:

[0038] coupling the CRS system to a machine vision inspection system that includes a motion mechanism; and

[0039] operating the CRS system as part of the machine vision inspection system, wherein the adjustment includes utilizing the motion mechanism of the machine vision system to cause the distance from the optical probe to the workpiece surface to correspond to a focus distance at which the workpiece surface is in focus when imaged by light passing through the narrowband spectral filter.

[0040] According to another aspect, a chromatic range sensor (CRS) system is provided that is operable to provide an in-focus image of a workpiece surface to be measured, wherein the image includes a measurement spot formed on the workpiece surface. The CRS system includes (a) an optical probe; (b) a first light source; (c) a CRS wavelength detector; (d) one or more processors; and (e) a memory.

[0041] An optical pen includes a housing; an input / output optical fiber including a fiber aperture configured to output light along a measurement optical path and receive reflected light along the measurement optical path; and a chromatic dispersion lens configuration having an optical axis defining a measurement axis of the chromatic confocal range sensor optical pen. The lens configuration includes in the measurement optical path and is configured to: receive light and output focused light to a workpiece surface having an axial chromatic dispersion such that different wavelengths are focused at different distances proximate the workpiece surface; and receive reflected light from the workpiece surface and focus at least a portion of the reflected light along the measurement optical path to a point proximate the fiber aperture.

[0042] The optical pen further includes a reflected light splitting configuration arranged to receive reflected light from the chromatic dispersion lens configuration and split the reflected light into a measurement portion and an imaging portion. The optical pen also includes a narrowband spectral filter arranged to filter at least a portion of the imaging portion of the reflected light; and a camera portion including an image detector configured to receive at least a portion of the imaging portion of the reflected light through the narrowband spectral filter for producing a camera image.

[0043] A first light source is configured to generate a first light of multiple wavelengths input to the optical pen.

[0044] The CRS wavelength detector includes a plurality of pixels each pixel position distributed along a measurement axis of the CRS wavelength detector configured to receive at least a portion of the measurement portion of the reflected light and provide output spectral profile data.

[0045] A memory is coupled to the one or more processors and stores program instructions that, when executed by the one or more processors, cause the one or more processors to at least:

[0046] operate the CRS system to measure a distance from the optical pen to the workpiece surface based on the output spectral profile data;

[0047] make an adjustment such that the distance from the optical pen to the workpiece surface corresponds to a focus distance at which the workpiece surface is in focus when imaged by light through the narrowband spectral filter; and

[0048] display the camera image of the workpiece surface including the measurement spot.

[0049] According to various embodiments of the present invention, imaging capability is integrated with the measurement capability of a CRS system to support guided light imaging of a measurement spot on a workpiece surface that is natural and robust (simple registration and alignment) to improve measurement operations using the CRS system. BRIEF DESCRIPTION OF DRAWINGS

[0050] The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0051] Figure 1 is a block diagram of one embodiment of an exemplary CRS system.

[0052] Figure 2 is an intensity profile plot from a CRS system illustrating a wavelength peak resulting from a wavelength reflected by a workpiece surface to be measured, where the pixel position of the peak corresponds to a measured distance to the workpiece surface.

[0053] Figure 3 illustrates three peak spectral profiles resulting from a workpiece surface positioned for green, blue, and red light foci, respectively, and three images of a measurement spot MS containing the workpiece surface taken at the respective locations.

[0054] Figure 4 is a diagram illustrating an exemplary embodiment of a machine vision inspection system including a CRS system for providing a focused image of a workpiece surface to be measured containing measurement spots formed thereon.

[0055] Figure 5 is a flowchart illustrating a method of operating a CRS system to provide a focused image of a workpiece surface to be measured containing measurement spots formed thereon. DETAILED DESCRIPTION

[0056] Figure 1 is a block diagram of one exemplary embodiment of a chromatic range sensor (CRS) system 100 including an optical pen 120, an electronics portion 160, and a user interface portion 171. Embodiments of the electronics portion 160 include a signal processor 166, a memory portion 168, and a source and detector subsystem 161 including a wavelength detector 162 and a broadband first light source 164. Figure 1 The CRS system 100 shown in FIG. 1 is a chromatic point sensor (CPS) system that measures a single measurement point at a time, but it will be understood that in other embodiments other sensor systems (e.g., a chromatic line sensor, etc.) can be utilized. In various embodiments, the wavelength detector 162 includes a detector array 163 of a spectrometer. The detector array 163 can include a plurality of pixels distributed along a measurement axis of the wavelength detector 162, where respective pixels receive respective wavelength signals and provide corresponding output spectral profile data.

[0057] The electronics section 160 is coupled to the optical pen 120 by an optical path that includes the input / output fiber 112. The input / output fiber 112 includes a fiber aperture 112a through which first light is output along a measurement optical path MOP that coincides with the optical axis OA of the optical pen 120, and through which reflected light is received along the measurement optical path MOP / optical axis OA. A first light source 164, controlled by the signal processor 166, is connected to input multi-wavelength light to the optical pen 120 through the input / output fiber 112.

[0058] The optical pen 120 includes a housing 130, an input / output fiber 112, an optical section 150, a reflected light splitting arrangement 107, a narrow band spectral filter 108, and a camera section 109. The optical section 150 includes a chromatic dispersion lens arrangement 150L having an optical axis OA that defines a measurement axis of the CRS optical pen 120. The lens arrangement 150L is configured to receive light and output focused light 121 to a workpiece surface 170s of a workpiece 170 having axial chromatic dispersion, such that different wavelengths are focused at different distances proximate the workpiece surface 170s. The lens arrangement 150L is configured to receive reflected light 122 from the workpiece surface 170s and focus at least a portion of the reflected light along the measurement optical path MOP to a point proximate the fiber aperture 112a.

[0059] Figure 1 Orthogonal XYZ coordinate axes are included as a frame of reference. The Z direction is defined as parallel to the optical axis OA of the optical pen 120, which in the illustrated example is the measurement optical path MOP. In various embodiments, the CRS system 100 is capable of making adjustments automatically such that the distance from the optical pen 120 to the workpiece surface 170s corresponds to the focusing distance at which the workpiece surface is in focus when imaged by the camera section 109, as will be described in greater detail below. In one example implementation, the adjustments can be made by placing the workpiece 170 on a translation stage 175 that includes an adjustment mechanism 175a, such as a controllable motor driving an actuator along a guide bearing, that is capable of translating the translation stage 175 along the Z axis, which coincides with the optical axis OA. As will be illustrated in greater detail in Figure 4 As will be illustrated in greater detail in FIG. 47, a workpiece 170' (i.e., similar to the workpiece 170) can be mounted on a translation stage 472 of a machine vision inspection system used with the CRS system 100, and as part of the adjustments, appropriate motion mechanisms can be provided to move the optical pen 120 along the Z axis direction such that the workpiece surface 170s' (i.e., similar to the workpiece surface 170s) will be at the height (distance from the optical pen 120) at which the workpiece surface is in focus when imaged by the camera section.

[0060] The reflected light splitting configuration 107 is arranged to receive the reflected light 122 from the chromatic dispersion lens configuration 150L and split the reflected light 122 into a measurement portion 122a and an imaging portion 122b. In various embodiments, the reflected light splitting configuration 107 is a beamsplitter. Generally, the reflected light splitting configuration 107 splits some of the reflected light 122 from the workpiece surface 170s into the imaging portion 122b to be used as imaging light, while the rest of the light constitutes the measurement portion 122a to be used as distance measurement light. The reflected light splitting configuration 107 directs the imaging portion 122b of the reflected light 122 toward the narrowband spectral filter 108 and the camera portion 109, and directs the measurement portion 122a of the reflected light 122 toward the fiber aperture 112a. In various implementations, the ratio of the measurement portion 122a to the imaging portion 122b of the reflected light is at least 5 to 1, and can be, for example, 9 to 1. When the ratio is 9 to 1, a 90 / 10 beamsplitter can be used to form the reflected light splitting configuration 107 such that the measurement portion 122a includes approximately 90% of the reflected light 122 and the imaging portion 122b includes approximately 10% of the reflected light 122.

[0061] The narrowband spectral filter 108 (interchangeably referred to as a light bandpass filter or a narrowband bandpass filter) is arranged to filter the imaging portion 122b of the reflected light so that only a defined narrowband of the imaging portion 122b of the reflected light reaches the camera portion 109. According to various exemplary embodiments, the spectral bandwidth of the narrowband spectral filter 108 is defined to include optimal imaging of the workpiece surface 170s at the measurement spot MS, which can be used as a guide light to help an operator properly position the workpiece surface relative to the CRS system 100. As known in the art, in various implementations, the spectral bandwidth can be defined in terms of / from a full width at half maximum (FWHM) determination (e.g., the spectral bandwidth of the narrowband spectral filter can be defined in terms of / from a FWHM determination of the narrowband spectral filter). In various embodiments, the spectral bandwidth of the narrowband spectral filter 108 can be less than 10 nanometers, or less than 5 nanometers (e.g., as having a spectral bandwidth of approximately 2 nanometers).

[0062] Generally, the narrow bandwidth of wavelengths that pass through the filter are in focus together when imaged by the camera 109, even with the axial chromatic dispersion caused by the lens configuration 150L. In contrast, wavelengths that do not fall within the spectral bandwidth of the narrowband spectral filter 108 (e.g., and thus can be primarily blocked / fi ltered by the narrowband spectral filter 108) can correspond to light that would be out of focus when / if imaged by the camera (e.g., for imaging the workpiece surface 170s) otherwise. More specifically, in various implementations, the spectral bandwidth of the narrowband spectral filter can be determined / selected / utilized to block / filter out-of-focus light (e.g., when the distance from the optical pen to the workpiece surface corresponds to a focus distance at which the workpiece surface is in focus when imaged by the light that passes through the narrowband spectral filter).

[0063] As will be described in greater detail below, in various embodiments, the measurement spot MS can be formed from a portion of the imaged portion 122b of the reflected light that includes the first light from the first light source 164 that is output from the fiber aperture 112a and reflected from the workpiece surface 170s. In various embodiments, it can be desirable for the spectral bandwidth of the narrowband spectral filter 108 to be such that the measurement spot MS formed in the camera image will remain relatively small (e.g., imaged from wavelengths that fall within the spectral bandwidth and thus pass through the narrowband spectral filter 108). For example, a relatively small measurement spot MS (e.g., for a guided light) can help a user to determine the precise location on the workpiece surface 170s that is being measured by the optical pen 120 (e.g., as opposed to a larger measurement spot MS that can provide a less precise indication of the location on the workpiece surface that is being measured). In some cases (e.g., for some diffuse workpieces as opposed to some highly reflective workpieces) and for some configurations of the imaging numerical aperture, such considerations can be a primary factor in selecting the spectral bandwidth of the narrowband spectral filter 108 to be used. In some such cases, it can be desirable to select a narrowband spectral filter 108 having a spectral bandwidth that is similar (e.g., approximately the same) to the spectral bandwidth of the received reflected light that is coupled back into the input / output fiber 112 through the fiber aperture 112a for measurement (e.g., such that the bandwidth of the narrowband spectral filter is no more than twice the spectral bandwidth of the light coupled back into the fiber). As some examples, if an optical pen is used in which the received reflected light that is coupled back into the input / output fiber 112 through the fiber aperture 112a for measurement has a spectral bandwidth of approximately 3 nanometers or 1 nanometer, a narrowband spectral filter 108 having an approximately similar / matching spectral bandwidth such as 3 nanometers or 2 nanometers or 1 nanometer can be selected / utilized.

[0064] By making the adjustment such that the optical pen 120 of the CRS system 100 is a distance from the workpiece surface 170s that corresponds to the spectral bandwidth of the narrowband spectral filter 108 at which light is in focus, a relatively in-focus image of the workpiece surface containing the measurement spot MS can be obtained. In various embodiments, as an alternative to making the adjustment mechanically by adjusting the distance between the optical pen 120 and the workpiece surface 170s, the adjustment can be made optically by changing the focusing properties of the chromatic dispersion lens configuration 150L such that the workpiece surface 170s, while maintaining the same physical distance from the optical pen 120, comes into focus when imaged from light that falls within the spectral bandwidth that passes through the narrowband spectral filter 108. Further alternatively, the adjustment can be made by changing the internal filter wavelength of the narrowband spectral filter 108 to match the wavelength that is in focus at the current position of the workpiece surface 170s along the Z-axis.

[0065] According to various embodiments, for system robustness, an image of the workpiece surface to be measured is captured in the middle of the CRS measurement range of the CRS system. In other words, the narrowband spectral filter 108 may have a center wavelength that approximately corresponds to the middle of the CRS measurement range of the CRS system. In various exemplary embodiments, the center wavelength may fall in the range of approximately 495 nm to 570 nm (e.g., corresponding to green in some cases), which is approximately in the middle of the exemplary CRS measurement range. In some embodiments, the measurement range may be between blue (e.g., when the workpiece is closer to the optical pen 120 in focus) and red (e.g., when the workpiece is farther away from the optical pen 120 in focus). Using light within the normal CRS measurement range (e.g., close to or in the middle of the CRS measurement range) to use light in the narrowband configuration disclosed herein makes the guiding light imaging of the measurement spot more natural and robust (e.g., through simple registration and alignment).

[0066] The camera section 109 includes an image detector and is configured to receive an imaging section 122b of reflected light passing through a narrowband spectral filter 108, thereby generating a camera image of the workpiece surface 170s containing a measurement spot MS of an optical pen 120 formed on the workpiece surface 170s. This will be described in detail below. Figure 3 The image shown (for example, see 330b), which includes an image of the workpiece surface 170s containing the measuring spot MS, can be displayed on a screen or the like included in the user interface section 171.

[0067] exist Figure 1 In the illustrated example, a second light source 111, such as a light-emitting diode (LED), a second beam splitter 114, such as a 50 / 50 beam splitter, a reflector 115, and a lens 116 are provided to form the propagation path of the imaging portion 122b of the reflected light (e.g., as part of the imaging optical path). As shown in the illustrated example, at least a portion of the measuring portion 122a and at least a portion of the imaging portion 122b propagate parallel to each other so as to be compactly arranged within the generally elongated housing 130 of the optical pen 120. This is one example of a configuration associated with the imaging portion 122b of the reflected light, and this disclosure is not limited to this particular example. For example, at least a portion of the propagation paths of the imaging portion 122b and the measuring portion 122a can be interchanged, such as by means of the optical axis OA of the illustrated optical pen 120 (e.g., in...). Figure 1 In the current instance, the camera portion 109 is placed at the location of the fiber optic aperture 112a, and the fiber optic aperture 112a is placed along the propagation path PP1, which is in... Figure 1The propagation path of the imaging portion 122b is illustrated in the present instance as being reflected by the reflector 115. As another example, the reflector 115 can be omitted so that the imaging portion 122b will follow a propagation path PP2 generally perpendicular to the optical axis OA of the optical pen 120 toward the camera portion 109, which will now be positioned along the propagation path PP2. The particular propagation paths of the measurement portion 122a and the imaging portion 122b of the reflected light can be configured in various ways depending on each desired application and configuration of the optical pen 120. Generally, in various exemplary embodiments, the measurement portion 122a and the imaging portion 122b of the reflected light extend along two different optical axes after being split by the reflected light splitting configuration 107.

[0068] The electronics portion 160 is coupled to or includes an imaging electronics portion 169. The imaging electronics portion 169 is configured to receive data from the camera portion 109 through the first signal line 113a and to provide control signals to the camera portion 109. The data from the camera portion 109 can be displayed on a display (e.g., monitor, etc.) included in a user interface portion 171. The imaging electronics portion 169 transmits control data through the second signal line 113b to control the operation of the second light source 111. The second light from the second light source 111 passes through the second beam splitter 114, is focused by the lens 116, is reflected by the reflector 115, and is directed by the reflected light splitting configuration 107 through the chromatic dispersion lens configuration 150L of the optical portion 150 to illuminate the workpiece surface 170s. As noted above, due to the normal operating characteristics of the chromatic dispersion lens configuration 150L, different wavelengths of the second light from the second light source 111 are focused at different distances proximate the workpiece surface 170s. As a result, if all of the corresponding reflected second light were used to form an image, such an image can otherwise appear to be out of focus, although, as will be described in greater detail below, the use of the narrowband spectral filter 108 enables the production of an in-focus image of the workpiece. After the second light from the second light source 111 is reflected as reflected second light from the workpiece surface 170s, it can comprise at least a portion of the reflected light 122. More particularly, the reflected light 122, as well as the measurement portion 122a and the imaging portion 122b, can each include both reflected first light and reflected second light.

[0069] As noted above, the reflected first light can be produced from light from the first light source 164 that is emitted through the fiber aperture 112a from the input / output fiber 112 and reflected as from the workpiece surface 170s. The corresponding reflected first light included in the corresponding measurement portion 122a can be received back through the fiber aperture 112a and used for measurement functions. The corresponding reflected first light included in the corresponding imaging portion 122b can be filtered by the narrowband spectral filter 108 and received by the camera 109 (e.g., for forming a measurement spot MS in an image that can be compared to an imaged spot source corresponding to the first light emitted from the fiber aperture 112a).

[0070] By contrast, as noted above, the reflected second light can be produced from light from the second light source 111. In various embodiments, any corresponding reflected second light included in the corresponding measurement portion 122a can not be used for measurement functions (e.g., when measurement functions are being performed, such as when light is being provided for determining output spectral profile data based on pixel data output from the detector array 163, the second light source 111 can be turned off so as to avoid measurement errors that can result from cross-talk between light from the two light sources 111 and 164, and such measurement functions can not be performed when the second light source 111 is on). Thus, in various embodiments, when measurement functions are being performed, the measurement portion 122a can include only reflected first light, the first light being from the first light source 164 provided through the fiber aperture 112a.

[0071] Corresponding reflected second light included in the corresponding imaging portion 122b can be filtered by the narrowband spectral filter 108 and received by the camera 109 (e.g., for forming an image of the workpiece surface 170s, as Figure 3 illustrated). In contrast to the first light emitted from the fiber aperture 112a, the second light from the second light source 111 can illuminate a relatively larger area of the workpiece surface. Thus, as part of the imaging portion 122b, the reflected second light can be used to form an image of the workpiece surface, while the reflected first light can be used to form an image of the measurement spot MS on the workpiece surface. As described herein, to form the images, the first light source 164 (e.g., for forming the measurement spot MS) can be turned on at the same time as the second light source 111, or can be turned on at different times, but in some cases still used to be included in an image (e.g., a single image) within a single integration / frame time of the camera 109. The resulting image includes both the illuminated portion of the workpiece surface (e.g., from the second light source 111) and the measurement spot MS (e.g., from the first light source 164), described below with respect to Figure 3 Certain examples are described in more detail below. The result is an image of the workpiece surface 170s including the measurement spot MS (e.g., used as a guide light), thereby helping a user to properly position the workpiece surface 170s and / or the CRS system 100 relative to each other for measuring a desired location on the workpiece surface 170s.

[0072] In some embodiments, the first light source 164 can be referred to as a measurement light source, with the first light being referred to as measurement light, the measurement portion of the reflected measurement light being used for measurement functions, and the imaging portion of the reflected measurement light being used for imaging the measurement spot MS. The second light source 111 can be referred to as an imaging light source, with the second light being referred to as imaging light, the imaging portion of the reflected imaging light being used for imaging the workpiece surface in accordance with the above-described operations.

[0073] In various exemplary embodiments, the wavelength range of the second light source 111 is selected to include wavelengths that substantially correspond to the spectral bandwidth of light passing through the narrowband spectral filter 108 to form an image of the workpiece surface 170s including the measurement spot MS formed thereon. For example, when the narrowband spectral filter 108 is configured with a spectral bandwidth such that a central wavelength selected from a range of between about 495 nm and 570 nm (e.g., in some cases corresponding to green, such as the narrowband spectral filter 108 having a spectral bandwidth from 530 nm to 532 nm with the central wavelength correspondingly at 531 nm) passes therethrough, the central wavelength is near the middle of the CRS measurement range of the CRS system 100 described above, a green LED can be used as the second light source 111 to provide light for illuminating the workpiece surface 170s.

[0074] In various embodiments, the second light source 111 can emit light having a spectral bandwidth (e.g., wavelength range) that is at least twice, five times, or ten times the spectral bandwidth of the narrowband spectral filter 108. For example, if the narrowband spectral filter 108 has a spectral bandwidth of 2 nm (e.g., from 530 nm to 532 nm with the central wavelength correspondingly at 531 nm), the second light source 111 can have a spectral bandwidth of at least 4 nm, 10 nm, or 20 nm (e.g., at least from 520 nm to 540 nm), such as the spectral bandwidth and / or central wavelength of the narrowband spectral filter 108 being near the middle of the spectral bandwidth of the second light source 111. Such a configuration can be advantageous in implementations where the wavelength range of the second light source 111 can drift (e.g., due to temperature, etc.), the wider spectral bandwidth of the second light source 111 helping to ensure that the emitted light will still include wavelengths falling within the spectral bandwidth of the narrowband spectral filter 108 even if drift is occurring. In various implementations, it can also be desirable for the second light source 111 to be a non-coherent light source (e.g., to avoid effects such as speckle), such non-coherent light sources in some cases can naturally have a relatively large spectral bandwidth (e.g., as compared to certain comparable coherent light sources, etc.). As another consideration, it can be desirable for the spectral bandwidth of the second light source 111 to be somewhat limited (e.g., to reduce energy consumption, etc.). For example, in some implementations, the spectral bandwidth of the second light source 111 can be less than 100 nm, or less than 50 nm.

[0075] In various embodiments, the second light source 111 can be turned off during at least some portions of the measurement operation (as opposed to the imaging operation) in which the CRS system 100 measures the distance to the workpiece surface 170s, to avoid measurement errors that can arise due to cross-talk between light from the two light sources 111 and 164. In embodiments in which there is some non-measurement time in the measurement operation due to CRS electronics, in some embodiments the second light source 111 can be turned on during the non-measurement time, for example one or more times during a single camera frame of the camera portion 109, in order to provide illumination for the imaging operation without interfering with the distance measurement operation of the CRS system 100 in each frame.

[0076] In various embodiments, the first light provided by the first light source 164 can be turned on during at least a portion of the imaging operation, as the first light from the first light source 164 can be used to form the measurement spot MS in the image to serve as the guide light. Thus, one approach is to have the first light source 164 "on" during both the CRS measurement operation and the imaging operation, while having the second light source 111 "on" only during the imaging operation and "off" during the CRS measurement operation.

[0077] For the measurement operation (e.g., for distance measurement to the workpiece surface 170s), the optical pen 120 is connected to the CRS electronics portion 160 and is operatively positioned relative to the workpiece surface 170s. Light emitted from the input / output fiber 112 through the fiber aperture 112a is focused by the optical portion 150, which includes a lens configuration 150L that provides axial chromatic dispersion such that different wavelengths are focused at different locations along the optical axis OA, as is well known for CRS systems. The input light is focused near the workpiece surface 170s, and light reflected from the workpiece surface 170s is refocused by the optical portion 150 onto the fiber aperture 112a (i.e., the measurement portion 122a of the reflected light is directed onto the fiber aperture 112a). For the measurement portion 122a, due to its axial chromatic dispersion, only one wavelength will have a focus distance that matches the measurement distance "Zl", which is the distance from a reference position RP that is fixed relative to the optical pen 120 to the position of the workpiece surface 170s (e.g., the height along the Z axis). The wavelength that is best focused on the workpiece surface 170s is the best focus wavelength at the fiber aperture 112a. Thus, primarily the best focus wavelength passes through the fiber aperture 112a and into the core of the input / output fiber 112. The input / output fiber 112 routes the signal light to the wavelength detector 162, which is used to provide output spectral profile data to determine the wavelength having the dominant intensity, which corresponds to the measurement distance Zl to the position of the workpiece surface 170s.

[0078] Wavelength detector 162 receives wavelength-dependent light intensity from detector array 163 as output spectral intensity profiles distributed along a measurement axis of detector array 163 (pixel data) on an array of pixels. Wavelength detector 162 operates to provide corresponding output spectral profile data (e.g., as will be described below with respect to FIG. 3) based on the pixel data output from detector array 163. Figure 2 More detail is described.

[0079] Figure 2 is a plot 200 of a wavelength-dispersed intensity profile from CRS system 100, illustrating an effective wavelength peak 202 resulting from a subset of measurement profile signals MS(p) representing wavelengths focused on and reflected by workpiece surface 170s. Figure 2 A system noise (bias) signal level MVbias is shown for pixels in detector array 163 when no measurement surface is present within the overall measurement range of CRS system 100. A signal level threshold MVThreshold is set to isolate the wavelength peak 202 (measurement profile signals MS) having a peak pixel coordinate (PPC), which is the pixel having the highest signal. All “V” values are in normalized volts for each of the 1,024 pixels along the “wavelength” measurement axis. “Normalized volts” assigns a value of 1.0 to the saturation voltage of detector array 163. In the illustrated embodiment, signal level threshold MVThreshold defines a lower limit of a distance-indicating subset of measurement profile signals MS(p) forming wavelength peak 202. Each of the measurement profile signals MS(p) has a signal level associated with each pixel p of detector array 163. Sub-pixel resolution distance-indicating coordinates (DIC) 204 can be computed by signal processor 166 according to previously known methods, where DIC (in sub-pixels) indicates a measurement distance Zl (in microns) to a location of workpiece surface 170s containing measurement spot MS formed thereon, by a distance calibration lookup table or the like stored in calibration portion of memory portion 168. In various embodiments, DIC 204 is determined in sub-pixel resolution based on the distance-indicating subset of measurement profile signals MS(p) forming wavelength peak 202 having a value greater than MVThreshold (e.g., according to a centroid or other computation / processing of intensity profile data contained in wavelength peak 202).

[0080] Figure 3 Three peak spectral profiles 330a-334a resulting from workpiece surface 170s positioned with respect to green, blue, and red light foci, respectively, and corresponding three images 330b-334b of the workpiece surface containing measurement spots MS formed thereon are plotted. A measurement axis (MA) indicated as pixel number corresponding to each peak spectral profile can be considered analogous to a wavelength axis (WA) having a wavelength scale (WS) as shown in FIG. 3.Figure 2 corresponding pixel number in the measurement axis. As Figure 3 illustrated, the green peak 330a represents a peak measured when the workpiece surface 170s is positioned (away from the reference position RP of the optical pen 120) at a position corresponding to the wavelength of green light being the position of the best focus light in the wavelength dispersion (chromatic dispersion) intensity profile of the workpiece surface 170s. The blue peak 332a represents a peak measured when the workpiece surface 170s is positioned at a position corresponding to the wavelength of blue light being the position of the best focus light in the wavelength dispersion intensity profile of the workpiece surface 170s. The red peak 334a is a peak measured when the workpiece surface 170s is positioned at a position corresponding to the wavelength of red light being the position of the best focus light in the wavelength dispersion intensity profile of the workpiece surface 170s.

[0081] The different positions of the green peak 330a, the blue peak 332a, and the red peak 334a along the measurement axis MA (in pixels) indicate that different wavelengths of dominant intensity correspond to different measurement distances from the reference position RP of the optical pen 120 to the workpiece surface 170s. In a typical embodiment, the workpiece surface 170s producing the blue peak 332a is positioned closest to the optical pen 120, then the workpiece surface 170s producing the green peak 330a, and finally the workpiece surface 170s producing the red peak 334a is positioned farthest from the optical pen 120.

[0082] Since the narrowband spectral filter 108 is configured to pass only a defined narrowband of the imaged portion 122b of the reflected light 122 to the camera portion 109, it is desirable for the workpiece surface 170s to be at a focus distance at which the workpiece surface 170s is in focus when imaged by light falling within the defined narrowband. This allows the camera portion 109 to capture an in-focus image of the workpiece surface 170s containing the measurement spot MS. For example, when the narrowband spectral filter 108 is configured to pass a narrowband of certain green wavelengths, certain green wavelengths will pass through the narrowband spectral filter 108, but wavelengths corresponding to blue light and red light will be blocked primarily. Thus, when the workpiece surface 170s is positioned at the green light focus distance to generate the green peak 330a, the focused (dominant) green light can pass through the narrowband spectral filter 108 to generate an in-focus green image 330b of the workpiece surface. Figure 3 Figure 3 In the example of FIG. 3B, the in-focus green image 330b contains sharp dark and light vertical lines on the workpiece surface and similarly sharp measurement spots MS.

[0083] ​On the other hand, when the workpiece surface 170s is positioned at the blue light focus distance (closer to the optical pen 120) or at the red light focus distance (farther from the optical pen 120), the focused blue light or the focused red light reflected from the workpiece surface 170s will be primarily blocked by the narrowband (e.g., green) spectral filter 108 and will primarily only allow the defocused green wavelengths to pass to generate a blurry image 332b or 334b of the workpiece surface including blurry dark and light vertical lines and a blurry measurement spot MS. Note that the blurry image 332b and the blurry image 334b are formed from the green light (i.e., including the defocused green wavelengths) that passes through the narrowband spectral filter 108 to the camera portion 109. Again, the images 332b and 334b are blurry because the focused blue light or red light is blocked and the images 332b and 334b are formed using only the defocused green light that passes through the narrowband spectral filter 108. As noted above, in this example embodiment, the second light provided by the second light source 111 can include green wavelengths (or otherwise correspond to the narrowband spectral filter 108), while the first light source 164 is a broadband light source (e.g., providing blue, green, red, etc. light) as part of normal CPS operation, such that the distance Z to the workpiece surface 170s can be measured at any distance within the measurement range of the optical pen (e.g., as described in more detail in the incorporated references).

[0084] To ensure that the image of the workpiece surface 170s including the measurement spot MS will be well focused for use as a guide light to help the user properly position the workpiece surface 170s relative to the CRS system 100, according to various exemplary embodiments, the CRS system 100 can be used to perform an adjustment (perform an auto-focus function to position the workpiece surface 170s at the focus distance) so that the workpiece surface 170s will be in focus when imaged by the narrowband light corresponding to the narrowband spectral filter 108.

[0085] In this regard, the CRS system 100 can operate in a plurality of modes, including a measurement mode, in which the distance from the optical pen 120 to the workpiece surface 170s is measured, and a pilot light mode, in which the measurement spot MS can be used as a pilot light to help the user properly position the workpiece surface 170s and / or the optical pen 120 relative to each other (in the X and Y axis directions) for the purpose of measurement operations and measuring a particular desired surface point / position on the workpiece surface. In the pilot light mode, the distance to the workpiece surface 170s is measured and adjusted to correspond to a focus distance (e.g., the distance is adjusted to correspond to a focal length, as corresponding to the narrow band spectral filter 108 as described above), and a focused image of the workpiece surface 170s including the measurement spot MS is taken by the camera portion 109 and displayed (e.g., on a display of the user interface portion 171). The user interface portion 171 can be configured to receive user input for operation of the CRS system 100 via any suitable means, such as a keyboard, touch sensor, mouse, etc. For example, the user interface portion 171 can include one or more operational mode selection elements (e.g., user selectable buttons) that can be operated by the user to select one of a plurality of operational modes of the CRS system 100.

[0086] In various embodiments, the user can select both the measurement mode and the pilot light mode, in response to which the CRS system 100 can operate in a time-division manner in the measurement mode and the pilot light mode, such that the user can perform measurement operations while intermittently using the pilot light to ensure proper positioning of the workpiece surface 170s and / or the optical pen 120 relative to each other (e.g., in the X and Y axis directions) for the purpose of the measurement operations. For example, when there is some non-measurement time in the measurement operations as described above, the imaging operation (in the pilot light mode) can be performed during the non-measurement time, such that pilot light imaging of the workpiece surface 170s including the measurement spot MS is provided. In various embodiments, the user interface portion 171 is configured to display on the screen information related to operation in any one of the plurality of operational modes, such as an image of the workpiece surface 170s including the measurement spot MS during the imaging / pilot light mode (see Figure 3 ) or the distance to the workpiece surface 170s measured by the CRS system 100 during the measurement mode.

[0087] As will be described below with respect to Figure 4In some exemplary embodiments, the CRS system 100 can be coupled to or incorporated into a measurement machine, such as a machine vision inspection system (MVIS) (or "vision system"). In particular, a measurement machine (e.g., a vision system) can be used with the CRS system 100 to perform an auto-focus function to position the optical pen 120 and / or the workpiece surface 170s relative to each other such that the workpiece surface is at a focus distance at which the workpiece surface is in focus when imaged by light falling within a narrow band of light through the narrow band spectral filter 108 as described above.

[0088] Figure 4 is a block diagram of a first exemplary implementation of a measurement system 400 that includes a measurement machine in the form of a machine vision inspection system (MVIS) 401 utilized in conjunction with a CRS system 100'. In various figures herein, reference numerals having like suffixes (e.g., reference numerals 1XX and 1XX') can refer to generally similar elements such that one of ordinary skill in the art can understand the operation of element 1XX' with limited description based on the previously described analog of similar element 1XX.

[0089] As known in the art, a machine vision inspection system ("vision system") can be used to obtain precise dimensional measurements of an object under inspection and to inspect various other object features. Such systems can include a computer and user interface 460, a camera (not shown), an optical imaging system 434, and a moveable precision stage 472, enabling the camera to scan features of a workpiece under inspection. Machine vision inspection systems having optical systems such as the optical imaging system 434 are described in U.S. Patent Nos. 7,454,053 and 8,085,295, which are hereby incorporated by reference in their entirety herein. Various aspects of machine vision inspection systems and control systems are also described in greater detail in U.S. Patent No. 7,324,682 ('682 patent) and U.S. Patent Publication No. 20050031191 ('191 publication), which are also hereby incorporated by reference in their entirety herein. As described in the '682 patent and the '191 publication, the machine vision inspection system (MVIS) 401 can include a vision system controller 410 that can be used to call up captured and stored workpiece inspection images, inspect and analyze workpiece features in such workpiece inspection images, and store and / or output inspection results.

[0090] As Figure 4As illustrated, an optical imaging system 434, including an objective lens 470, has an optical axis OA and can be used to magnify and image the surface of a workpiece on a stage 472. The optical imaging system 434 can obtain an image focus by moving along a Z-axis guide bearing 434a, and in various embodiments, can be moved by a motion mechanism 434b (e.g., a controllable motor that drives actuators to move the optical imaging system 434 along the Z-axis). In various embodiments, the motion mechanism 434b can be controlled by a motion controller 420 in a vision system controller 410. In various embodiments, the workpiece can be located within the field of view (FOV) of the optical imaging system 434 on the workpiece stage 472, which is movable along the X and Y axes on the guide bearing 472a. The workpiece stage 472 can be moved by the motion mechanism 472b (e.g., a controllable motor that drives actuators to move the workpiece stage 472 along the X and Y axes). In various embodiments, the motion mechanism 472b can be controlled by the motion controller 420.

[0091] The machine vision inspection system (MVIS) 401 may include a detection system 436, which may be mounted to or otherwise coupled to the turntable of the MVIS 401 (forming the optical imaging system 434) via a suitable bracket device (not shown). The detection system 436 may be adapted to hold the optical pen 120' of the CRS system 100' for use in conjunction with various measurement and imaging functions, such as those described above. The optical pen 120' will be understood to include... Figure 1 The optical pen 120' may contain similar or identical components (e.g., including standard optical pen components, as well as narrowband spectral filters, cameras, second light sources, etc.). The optical pen 120' may be mechanically coupled to the probe assembly 439, and a bus containing fiber optic cable 112' and signal lines 113' (e.g., similar to fiber optic cable 112 and signal lines 113a and 113b) connects the optical pen 120' to the optical pen electronics portion 160' of the CRS system 100'. In the illustrated embodiment, the optical pen electronics portion 160' is part of the vision system controller 410 and may include imaging electronics portions (e.g., similar to...). Figure 1 (Imaging electronics section 169). The MVIS 401 may include associated control software that is largely equivalent to that available through the QUICKVISION® QV Apex series vision systems from Mitutoyo America Corporation (MAC) in Aurora, Illinois.

[0092] In this configuration, standard coordinate measuring machine technology can be utilized in conjunction with standard machine vision technology to utilize the motion controller 420 to control the probe system 436 to automatically position the optical pen 120' with the measurement beam 196' relative to the surface 170s' of the workpiece 170'. Additionally or alternatively, the machine vision control system 401 can be used to move the workpiece stage 472 and the workpiece 170' and / or the optical imaging system 434 so that measurement and imaging functions (e.g., those described herein and in incorporated references, etc.) can be performed. In particular, the CRS system 100' can include all of the elements and capabilities described above (e.g., including those for providing a focused image of the workpiece surface 170s' including the measurement spot MS (e.g., as formed by the measurement beam 196'), etc.). Figures 1 to 3

[0093] As Figure 4 illustrated, the probe system 436 is movable along a Z-axis guide bearing 436a and can be moved by a motion mechanism 436b (e.g., a controllable motor driving an actuator to move the probe system 436 along the Z-axis). In various embodiments, the motion mechanism 436b can be controlled by the motion controller 420. In various embodiments, the probe system 436 can be coupled to the optical imaging system 434 (e.g., via a suitable carriage arrangement to a turntable containing the optical imaging system 434) so that one or both of the Z-axis guide bearings 434a and / or 436a can be included in and / or otherwise used to enable Z-axis motion of the optical imaging system 434 and the probe system 436 to be controlled by one or both of the motion mechanisms 434b or 436b. In some embodiments, the turntable of the MVIS 401 and the optical pen 120' of the CRS system 100' are moved along the Z-axis direction in tandem. In various embodiments, the Z measurement ranges of the optical imaging system 434 and the optical pen 120' can be calibrated or referenced relative to each other and relative to the Z-axis controller coordinates of the MVIS 401. The optical pen electronics portion 160' and the vision system controller 410 can be configured to exchange data and control signals in accordance with known methods to support coordinated adjustment (e.g., mechanical movement) of the optical pen 120' and the optical imaging system 434.

[0094] Figure 4 Blocks representing exemplary control circuits and / or routines are illustrated. These blocks include the computer and user interface 460, the vision system controller 410, which can act as a host system for communicating with the optical pen electronics portion 160', and which includes the motion controller 420 and the probe controller 430. All of the blocks are interconnected to each other and to various components of the machine vision and inspection system 401 by power and control buses 415, in Figure 4 ​In embodiments, the power and control bus is connected to the probe system 436 through connection 492. The optical pen electronics portion 160' can perform measurements using the optical pen 120' and exchange control and data signals with the computer and user interface 460 and / or vision system controller 410. The motion controller 420 of the MVIS 401 can be used to control a motion mechanism (e.g., motion mechanism 436b) for adjusting the distance between the optical pen 120' and the workpiece surface 170s' to correspond to a distance at which the workpiece surface 170s' is in focus when imaged by the second light falling within the narrow band of the narrow band spectral filter of the optical pen 120' (e.g., so that the surface 170s' of the workpiece 170' and the measurement spot MS will be in focus in the image). As described above, in various embodiments, the workpiece 170' can also be positioned in the X and Y directions relative to the optical pen 120' (e.g., by movement of the workpiece stage 472, which can be moved in the X and Y axes on guide bearings 472a, as can be controlled by the motion controller 420).

[0095] As described above, in various embodiments, the spectral bandwidth of the narrow band spectral filter included in the optical pen 120' can be defined / selected for optimal imaging of the workpiece surface 170s' including the measurement spot MS, which can be used as a guide light to help an operator properly position the workpiece surface 170s' relative to the optical pen 120' of the CRS system 100' (e.g., in the X and Y axis directions). In general, wavelengths passing through the narrow bandwidth of the narrow band spectral filter can be mostly in focus together when imaged by the camera of the optical pen 120', even with axial chromatic dispersion caused by the lens configuration of the optical pen 120'. In contrast, wavelengths not falling within the spectral bandwidth of the narrow band spectral filter (e.g., and thus can be primarily blocked / filtered by the narrow band spectral filter) can correspond to light that would be out of focus when / if imaged by the camera (e.g., for imaging of the workpiece surface 170s'). More specifically, in various embodiments, the spectral bandwidth of the narrow band spectral filter can be determined / selected / utilized to block / filter out-of-focus light (e.g., when the distance from the optical pen 120' to the workpiece surface 170s' corresponds to a focus distance at which the workpiece surface 170s' is in focus when imaged by the light passing through the narrow band spectral filter). As described above, in various embodiments, the spectral bandwidth of the narrow band spectral filter can have a center wavelength that corresponds approximately to the middle of the CRS measurement range of the CRS system (e.g., the center wavelength falls within 10% of the middle of the CRS measurement range). Using light within the normal CRS measurement range (e.g., near or at the middle of the CRS measurement range) for the guide light imaging of the measurement spot using the narrow band configuration as disclosed herein makes the guide light imaging of the measurement spot more natural and robust (e.g., through simple registration and alignment).

[0096] In one embodiment of the optical pen 120 / 120' utilizing the chrominance range sensor system scanning along the path of the measurement spot on the workpiece surface, the process for capturing images (i.e., for mapping the location of the measurement spot on the workpiece) can be performed at different selected locations along the measurement path. This can require the optical pen to be individually positioned along the Z axis to be at the correct height to match the distance of the wavelength focus by the narrowband filter at each measurement spot on the workpiece surface. For example, in one embodiment, images can be captured showing the measurement spot at the start and end points of the measurement path to confirm that the measurement spot is at the correct location on the workpiece at the start and end points of the measurement path. If desired, some additional images can also be taken for various points along the measurement path. Such imaging can be performed prior to or after the measurement along the measurement path, including individually positioning the optical pen with respect to the workpiece to image those surface points and capturing the images prior to or after the measurement process of the surface points along the path. Alternatively, the imaging process can be performed as part of or during the process for measuring the surface points along the path.

[0097] To capture each focus image of the workpiece surface containing the measurement spot MS, the Z position of the optical pen can need to be adjusted so that the measurement spot on the workpiece is at the correct Z distance from the optical pen to correspond to the distance of focus at the wavelength that matches (i.e., passes through) the narrowband spectral filter. For example, after capturing the first image at the start of the path as described above, to make a measurement at a point along the measurement path, the optical pen can be held at the same Z position (e.g., the same Z position within the machine coordinate system or other position at which the first image was focused) while the pen is moved in the X and Y axis directions with respect to the workpiece surface (e.g., by moving the stage 472 in the X and Y directions in the coordinate system 470 in FIG. 4B). If all of the measurement spots along the measurement path fall within the measurement range R of the optical pen, for example for a relatively flat workpiece, the measurement spot is positioned at a Z height, and for that measurement spot the narrowband spectral filter 108 (e.g., green) can be substantially in the middle of the range of the optical pen, then this approach works. In such cases, when the optical pen is moved in the X and Y directions, any measurement points that vary slightly up and down from that Z height as can occur on a relatively flat workpiece surface can still be within the measurement range R of the optical pen at the Z position. Figure 4

[0098] ​Alternatively, some of the measurement points along the path can be above or below the measurement range R of the optical pen at the Z position, for which the Z position of the optical pen can need to be adjusted so that those measurement spots will fall within the measurement range. Then, at the end of the measurement path, for whatever Z height the final / endpoint measurement point is at, the process for capturing a focused image of the workpiece surface can be performed, including adjusting the Z distance (e.g., moving the optical pen along the Z axis) so that the final measurement spot along the measurement path on the workpiece is at the correct Z distance from the optical pen to correspond to a distance that is in focus at the wavelength that matches the narrowband spectral filter 108.

[0099] For any surface point for which the imaging process is performed, it can not be necessary to perform an additional measurement process for that surface point. More specifically, in various embodiments, the imaging process itself (e.g., as described herein) can include performing a measurement process to determine the extent to which the distance between the optical pen and the workpiece is adjusted to bring the workpiece surface to a focused distance (e.g., relative to the narrowband spectral filter 108 and the camera 109). More specifically, according to various embodiments, the imaging process according to the present disclosure that includes an autofocus function can include: (1) a measurement of the initial distance between the optical pen and the surface point, and (2) an adjustment of the distance (e.g., by moving the optical pen in the Z direction) to a focused distance that corresponds to the wavelength of the narrowband spectral filter so that the image of the workpiece surface will be in focus. Thus, as part of the imaging process, step (1) can measure the initial distance to the workpiece surface point, and step (2) can determine the adjustment made to the initial distance in order to obtain an image that is in focus, and thus the current distance to the workpiece surface point (after the adjustment) is known or can otherwise be calculated based on the results from steps (1) and (2). Optionally, step (3) can be performed to take another measurement of the current distance to the workpiece surface point (to confirm the accuracy of the motion mechanism (e.g., the Z axis motion mechanism 436b of the measurement machine 436, etc.) of the CRS system 100) and / or to confirm that the image of the workpiece surface point is in focus. Figure 4

[0100] Figure 5 is a flowchart illustrating a method 500 of operating a CRS system to provide a focused image of a workpiece surface that includes measurement spots MS formed thereon. The CRS system is configured in accordance with the embodiments described above. Step 502 includes operating the CRS system 100 to measure a distance from the optical pen 120 to the workpiece surface 170s based on the CRS output spectral profile data. Step 504 includes making an adjustment so that the distance from the optical pen 120 to the workpiece surface 170s corresponds to a focus distance at which the workpiece surface 170s is in focus when imaged by light falling within the narrowband through the narrowband spectral filter 108. In various embodiments, the adjustment can be made by using the translation stage 175 and adjustment mechanism 175a of the CRS system 100 as shown in Figure 1 Figure 4 ​​The Z-axis motion mechanism 436b and Z-axis guide bearing 436a, among others, shown adjust the position of the workpiece surface 170s relative to the optical pen 120 along the Z-axis. Optical adjustments can also be made by changing the focusing properties of the chromatic dispersion lens arrangement 150L such that the workpiece surface 170s is brought into focus when imaged by light falling within the narrow band of the narrow band spectral filter 108, despite being held at the same physical distance from the optical pen 120. Further alternatively, adjustments can be made by changing the internal filter wavelength of the narrow band spectral filter 108 to match the wavelength that is in focus at the current position of the workpiece surface 170s along the Z-axis.

[0101] Step 506 includes displaying an image of the measurement spot MS of the optical pen 120 on the workpiece surface 170s based on the imaged portion 122b of the reflected light 122 that includes light passing through the narrow band spectral filter and captured by the camera portion 109 (i.e., an image of the workpiece surface 170s including the measurement spot MS formed thereon). In various embodiments, the displayed image can resolve workpiece features of 2 μιη or more around the measurement spot MS in the case that the workpiece surface 170s is in focus. In various embodiments, a resolution of 2 μιη is sufficient for the purpose of properly positioning the workpiece surface 170s relative to the CRS system 100. As noted above, with respect to such an arrangement, the spectral bandwidth of the narrow band spectral filter 108 can be defined / selected for optimal imaging of the workpiece surface 170s including the measurement spot MS, which can be used as a guide light to help an operator properly position the workpiece surface 170s relative to the CRS system 100 (e.g., in the X-axis and Y-axis directions).

[0102] In general, the various blocks outlined herein can be configured to operate using assembly and operations that are similar or identical to those used in the prior art for similar operations. It should be appreciated that the operations of the various blocks outlined herein can be performed using a general purpose processor, and that specialized circuitry and / or routines can be incorporated for associated blocks where specific functionality is desired. In various embodiments, the circuitry and / or routines associated with the various blocks can be combined with other circuitry and / or routines associated with other blocks, and / or the circuitry and / or routines associated with the various blocks can be split into separate circuits and / or routines.

[0103] While preferred embodiments of the application have been shown and described, modifications and substitutions can be made by persons skilled in the art x based on the teachings of the present disclosure. For example, a CRS system containing a chromatic point sensor (optical pen) is shown herein. However, a CRS system containing a chromatic line sensor can be configured to operate according to the systems and methods disclosed herein. It is to be understood that these and other alternatives can be employed without departing from the principles disclosed herein. In addition, various embodiments described above can be combined to provide further embodiments. All U.S. patents mentioned in this specification are incorporated herein by reference in their entirety. If necessary, the concepts of various patents and applications can be employed to provide additional embodiments, which can modify aspects of the embodiments.

[0104] These and other changes can be made to the specific implementations in light of the above detailed description. In general, the terms used in the following claims should not be construed to limit the claims to the specific implementations disclosed in the specification and the claims, but should be construed to include all possible implementations along with the full scope of equivalents to which such claims are entitled.

Claims

1. A colorimetric range sensor CRS system operable to provide a focused image of a workpiece surface to be measured, the image comprising a measurement spot formed on the workpiece surface, the CRS system comprising: (a) An optical pen, comprising: case; An input / output optical fiber includes an optical fiber aperture configured to output light along a measurement optical path and receive reflected light along the measurement optical path. A chromatic dispersive lens configuration having an optical axis defining the measurement axis of a chromaticity confocal range sensor optical pen, wherein the lens configuration is included in the measurement optical path and is configured to: The light is received and focused onto the surface of a workpiece with axial dispersion, such that different wavelengths are focused at different distances from the surface of the workpiece. as well as The reflected light is received from the surface of the workpiece and at least a portion of the reflected light is focused along the measurement optical path to a point near the fiber optic aperture. A reflected light splitting configuration is arranged to receive the reflected light from the chromatic dispersive lens configuration and split the reflected light into a measurement portion and an imaging portion; A narrowband spectral filter is arranged to filter at least a portion of the imaging portion of the reflected light; and The camera section includes an image detector configured to receive at least a portion of the imaging section of the reflected light passing through the narrowband spectral filter for generating a camera image; (b) A first light source configured to generate multi-wavelength first light input to the optical pen; (c) A CRS wavelength detector comprising a plurality of pixels, each pixel position distributed along the measurement axis of the CRS wavelength detector, configured to receive at least a portion of the measurement portion of the reflected light and provide output spectral profile data; and (d) A processing section configured to process the output spectral profile data to measure the distance from the optical pen to the workpiece surface, and to make adjustments such that the distance from the optical pen to the workpiece surface corresponds to the focusing distance at which the workpiece surface is in focus when imaged by the light passing through the narrowband spectral filter, wherein the light not passing through the narrowband spectral filter includes defocused light.

2. The CRS system of claim 1, wherein after the adjustment is made by the processing section, the corresponding camera image includes a measurement spot on the surface of the workpiece, wherein the measurement spot is formed by a portion of the imaging section of the reflected light, the reflected light including first light from the first light source output from the fiber optic aperture and reflected by the surface of the workpiece.

3. The CRS system of claim 1, further comprising a second light source that generates second light input to the chromatic dispersion lens configuration, wherein the imaging portion includes reflected second light reflected from the workpiece surface.

4. The CRS system according to claim 3, wherein the second light source comprises a light-emitting diode (LED).

5. The CRS system according to claim 3, wherein the spectral bandwidth of the narrowband spectral filter falls within the spectral bandwidth of the second light source.

6. The CRS system according to claim 1, wherein the narrowband spectral filter has a spectral bandwidth of less than 10 nanometers.

7. The CRS system according to claim 1, wherein the narrowband spectral filter has a spectral bandwidth of less than 5 nanometers.

8. The CRS system of claim 1, wherein the spectral bandwidth of the narrowband spectral filter and the spectral bandwidth of the received reflected light coupled back into the input / output optical fiber through the optical fiber aperture do not exceed twice the spectral bandwidth coupled back into the optical fiber.

9. The CRS system of claim 1, wherein the narrowband spectral filter has a center wavelength corresponding to the middle portion of the CRS measurement range of the CRS system.

10. The CRS system of claim 1, further comprising a screen portion configured to display the camera image.

11. The CRS system of claim 1, wherein the processing portion is capable of operating in multiple modes, the multiple modes including: a measurement mode, wherein the measurement portion measures the distance from the optical pen to the workpiece surface based on the reflected light; and a guide light mode, wherein the imaging portion generates the camera image of the workpiece surface based on the reflected light, and in the guide light mode, the camera image includes the measurement spot configured to serve as a guide light.

12. The CRS system of claim 1, wherein the adjustment made by the processing section includes making the distance from the optical pen to the workpiece surface correspond to the focusing distance.

13. The CRS system of claim 12, wherein the adjustment includes using a motion controller to adjust the distance from the optical pen to the workpiece surface.

14. The CRS system of claim 13, wherein the motion controller is part of a machine vision inspection system, and the optical pen is coupled to the machine vision inspection system.

15. The CRS system of claim 1, wherein the reflected light splitting configuration includes a beam splitter.

16. The CRS system of claim 1, wherein the ratio of the measurement portion to the imaging portion is at least 5 to 1.

17. The CRS system of claim 1, wherein at least a portion of the measurement portion of the reflected light and at least a portion of the imaging portion of the reflected light propagate parallel to each other.

18. The CRS system of claim 1, wherein the measurement portion and the imaging portion of the reflected light extend along two different optical axes after being segmented by the reflected light segmentation configuration.

19. A method for operating a colorimetric range sensor (CRS) system to provide a focused image of the surface of a workpiece to be measured, including a measurement spot. The CRS system includes: (a) An optical pen, comprising: case; An input / output optical fiber includes an optical fiber aperture configured to output light along a measurement optical path and receive reflected light along the measurement optical path. A chromatic dispersive lens configuration having an optical axis defining the measurement axis of a chromaticity confocal range sensor optical pen, wherein the lens configuration is included in the measurement optical path and is configured to: The light is received and focused onto the surface of a workpiece with axial dispersion, such that different wavelengths are focused at different distances from the surface of the workpiece. as well as The reflected light is received from the surface of the workpiece and at least a portion of the reflected light is focused along the measurement optical path to a point near the fiber optic aperture. A reflected light splitting configuration is arranged to receive the reflected light from the chromatic dispersive lens configuration and split the reflected light into a measurement portion and an imaging portion; A narrowband spectral filter is arranged to filter at least a portion of the imaging portion of the reflected light; and The camera section includes an image detector configured to receive at least a portion of the imaging section of the reflected light passing through the narrowband spectral filter for generating a camera image; (b) A first light source configured to generate multi-wavelength first light input to the optical pen; and (c) A CRS wavelength detector comprising a plurality of pixels, each pixel position distributed along the measurement axis of the CRS wavelength detector, configured to receive at least a portion of the measurement portion of the reflected light and provide output spectral profile data; The method includes: The CRS system is operated based on the output spectral profile data to measure the distance from the optical pen to the workpiece surface; Adjustments are made such that the distance from the optical pen to the workpiece surface corresponds to the focusing distance at which the workpiece surface is focused when imaged by the light passing through the narrow-band spectral filter; and Displays a camera image of the workpiece surface containing the measurement light spot.

20. The method of claim 19, further comprising: The workpiece surface is illuminated with second light input to the chromatic dispersion lens configuration, wherein the second light includes wavelengths falling within the spectral bandwidth of the narrow-band spectral filter, and the imaging portion includes reflected second light for imaging the workpiece surface.

21. The method of claim 20, wherein the imaging portion further comprises a reflected first light for imaging the measurement spot, wherein the camera image comprises an image of the workpiece surface and an image of the measurement spot on the workpiece surface, for the reflected first light.

22. The method of claim 19, wherein the narrowband spectral filter has a center wavelength corresponding to the middle portion of the CRS measurement range of the CRS system.

23. The method of claim 19, further comprising: The CRS system is coupled to a machine vision inspection system that includes a motion mechanism; as well as The CRS system is operated as part of the machine vision inspection system, wherein the adjustments made include using the motion mechanism of the machine vision inspection system to make the distance from the optical pen to the workpiece surface correspond to the focusing distance at which the workpiece surface is focused when imaged by the light passing through the narrow-band spectral filter.

24. A colorimetric range sensor CRS system operable to provide a focused image of a workpiece surface to be measured, the image comprising a measurement spot formed on the workpiece surface, the CRS system comprising: (a) An optical pen, comprising: case; An input / output optical fiber includes an optical fiber aperture configured to output light along a measurement optical path and receive reflected light along the measurement optical path. A chromatic dispersive lens configuration having an optical axis defining the measurement axis of a chromaticity confocal range sensor optical pen, wherein the lens configuration is included in the measurement optical path and is configured to: The light is received and focused onto the surface of a workpiece with axial dispersion, such that different wavelengths are focused at different distances from the surface of the workpiece. as well as The reflected light is received from the surface of the workpiece and at least a portion of the reflected light is focused along the measurement optical path to a point near the fiber optic aperture. A reflected light splitting configuration is arranged to receive the reflected light from the chromatic dispersive lens configuration and split the reflected light into a measurement portion and an imaging portion; A narrowband spectral filter is arranged to filter at least a portion of the imaging portion of the reflected light; and The camera section includes an image detector configured to receive at least a portion of the imaging section of the reflected light passing through the narrowband spectral filter for generating a camera image; (b) A first light source configured to generate multi-wavelength first light input to the optical pen; (c) A CRS wavelength detector comprising a plurality of pixels, each pixel position distributed along the measurement axis of the CRS wavelength detector, configured to receive at least a portion of the measurement portion of the reflected light and provide output spectral profile data; (d) One or more processors; and (e) A memory coupled to the one or more processors and storing program instructions that, when executed by the one or more processors, cause the one or more processors to at least: The CRS system is operated based on the output spectral profile data to measure the distance from the optical pen to the workpiece surface; An adjustment is made such that the distance from the optical pen to the workpiece surface corresponds to the focusing distance at which the workpiece surface is focused when imaged by the light passing through the narrow-band spectral filter; as well as Displays a camera image of the workpiece surface containing the measurement light spot.

Images