System and method for reduced-speckle laser line generation

Abstract

To reduce a speckle in a laser system.SOLUTION: An irradiation device for reducing a speckle phenomenon in light reflected from an irradiation object comprises: a laser; a linear diffuser which is located in an optical path between the irradiation object and a laser and diffuses parallel laser light to a plane fan expanding in one plane crossing at least a portion of the irradiation object; and a beam deflector which guides the parallel laser light projected to the beam deflector and sweeps over a plurality of positions on the linear diffuser within the exposure time in which the irradiation object is irradiated with scattered light. The plurality of positions exists over a distance crossing the linear diffuser. By giving the sufficiently non-correlated speckle pattern in an imaging element for light reflected from the crossing with the irradiation object of the plane fan light, addition is non-coherently performed when being imaged by the imaging element within the exposure time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] [Related Applications] This application claims the benefit of priority pursuant to 35 U.S.C. § 119(e)(1) to U.S. Provisional Patent Application No. 62 / 448,250, entitled "SYSTEM AND METHOD FOR REDUCED-SPECKLE LASER LINE GENERATION," filed January 19, 2017, and U.S. Patent Application No. 15 / 675,629, entitled "SYSTEM AND METHOD FOR REDUCED-SPECKLE LASER LINE GENERATION," filed August 11, 2017, the teachings of which are expressly incorporated herein by reference.

[0002] [Technical field] The present disclosure relates to systems, devices, and methods for generating and projecting a laser line, and in particular to systems, devices, and methods for generating and projecting a laser line, such as may be used in three-dimensional (3D) machine vision systems. [Background technology]

[0003] Speckle is a phenomenon that affects all lasers and laser beam emitters. It occurs when the roughness of the surface creates tiny diffraction regions. When a laser is shone on a surface with these diffraction regions, it produces a random pattern of "speckles". This occurs because many waves of the same frequency but different phases and amplitudes interfere and coherently add together to produce a wave whose amplitude (and therefore intensity) varies randomly. When a light wave is shone on a surface, diffraction theory dictates that each point on the surface behaves as a source of a second-order spherical wave. This means that the light at any point in the scattered light field is made up of waves scattered from each point on the surface. If the surface is rough enough to produce path length differences greater than one wavelength, then the path length differences will cause phase changes greater than 2π, resulting in random variations in the amplitude and intensity of the resulting light. Also, when using low-coherence light (i.e. light that is made up of many wavelengths), speckle patterns are usually not observed because the speckle patterns produced by the individual wavelengths have different sizes and are usually smoothed out, but for coherent light sources such as lasers, speckle patterns are unavoidable.

[0004] Speckle is a problem in imaging applications, for example laser displacement sensor (DS) systems. Such laser DS systems project a planar fan of light onto an object, which intersects with the 3D surface of the object, which faces the DS along an illumination contour (also called an illumination line). Note that if the 3D surface of the object is itself planar, the intersection of the planar fan light with the 3D surface will be a portion of a true straight line. However, if the 3D surface of the object is curved, the intersection of the planar fan light with the 3D surface will be along a curve that represents the curved contour of the 3D surface. The planar fan projected onto the object by a laser DS system contains one or more laser fans. Such laser fans can be formed, for example, by passing a laser beam through an aspheric lens (such as a Powell lens) or other suitable generators (such as a cylindrical lens, holographic, cylindrical array, linear diffuser, or a combination of these). The camera sensor of the laser DS system picks up the light reflected from the part of the 3D surface that corresponds to the illumination contour along a camera axis that is not parallel to the axis of the plane fan. The laser DS system then uses the light received from this illumination line (also called line light) to image the illumination line on the camera sensor. A processor associated with the laser DS system then uses the image of the illumination line to perform triangulation on the 3D surface contour. However, the picked-up line light has uneven and asymmetric irregularities due to speckle, so the position of the illumination line imaged on the camera sensor is not very accurate. In other words, unevenness in the illumination line image and asymmetry perpendicular to the axis of the illumination line are manifested as errors in the height of the 3D surface. Reducing the speckle reduces the uncertainty and improves the accuracy of the contour measurement by the laser DS system.

[0005] There are several current techniques that attempt to reduce speckle, such as the use of a movable diffuser in the fixed beam path to incoherently superimpose random speckle in the image of the beam with the average of uncorrelated speckle patterns. However, these diffusers have the drawback of spreading the beam in a certain direction, degrading the quality of the beam profile, and also tend to be relatively heavy, requiring complex mechanisms to move the diffuser and limiting the speed at which the speckle pattern can be changed (and thus the frame rate of the system). Other speckle reduction methods, such as those involving wavelength broadening, also have the drawback of changing the extent (image range), adding cost, complexity, and / or other drawbacks. Thus, these techniques are less than desirable for practical configurations for delivering laser beams.

[0006] There have also been attempts to precisely scan objects using a planar fan of diffuse light. In general, most scanning configurations rely on a moving object, camera, and / or illuminator, whose motion is tracked and translated into relative distance by a vision system processor, thus requiring mechanical systems that are subject to wear and degradation due to the conditions of the scanning environment. Summary of the Invention

[0007] The disclosed technique overcomes the deficiencies of the prior art by moving (e.g., laterally, circularly) a coherent light (laser) beam through a stationary linear diffuser (e.g., a machined linear diffuser with a flat-top intensity profile, a hologram or other diffusing element, and / or a cylinder array). This allows for a sufficiently fast change in the local phase of the illumination generated at the point where the planar fan of diffused light projected through the diffuser onto the 3D surface intersects with the 3D surface. This is because the beam is redirected by periodically moving a relatively small mass using a moving mirror structure. For example, a MEMS mirror or other structure without a moving mass (e.g., a solid beam deflector such as an AOM) may be used as the moving structure. This structure allows for a relatively short exposure time because the projected phase and thus the imaged speckle pattern change rapidly compared to the exposure time. The use of a linear diffuser in this way allows for a high-quality planar fan to be obtained. A high quality planar fan is one that is substantially free of diffusion and / or growth in a direction substantially perpendicular to the axis of the planar fan (i.e., through the thickness of the planar fan). In embodiments such as the DS that use an imaging sensor, the beam travel speed is at least 1 / 2 cycle (side-to-side movement) per image frame, allowing the imaging sensor to capture the entire length of the illumination line within the image scene. The illumination line generated by the diffuser by projecting a diffuse planar fan onto a work surface can be maintained substantially fixed on the work surface by adding a field lens. The addition of the field lens reduces frame-to-frame and intra-beam variations in illumination intensity, which may result from partial scans that are less than or greater than one-half (1 / 2) cycle. In operation, the presence of a distance across the diffuser provides a sufficiently uncorrelated speckle pattern within the exposure time, which allows for substantial averaging into a smooth illumination line, while reducing speckle contrast.In a further embodiment, a two degree of freedom mirror component (such as a MEMS) can be added to the above arrangement to generate a planar fan along a first direction and scan the target surface along a second (orthogonal) direction, typically with a high frequency scan in the first direction and a slower frequency scan in the second direction.

[0008] In an exemplary embodiment, a system and method for generating an illumination line for application to a 3D work surface with reduced speckle includes a laser source (e.g., an oscillating laser source) in the form of a parallel beam (e.g., a collimated beam) and a linear diffuser. The linear diffuser receives at least a portion of the moving parallel beam, forms a planar fan from the light passing through the linear diffuser, and projects the planar fan of diffuse light onto the 3D work surface to form the illumination line as the intersection of the planar fan with the 3D work surface. The moving part moves the parallel beam to have a scanning behavior (e.g., a periodic sweeping behavior) substantially in one or more planes. For example, the laser source may include a fixed laser beam source and a moving beam deflector (e.g., a periodic moving beam deflector) driven by the moving part. As a non-limiting example, the beam deflector may include a MEMS mirror. Alternatively, the beam deflector may be driven by another mechanism (e.g., a galvanometer) or may be a solid-state unit (e.g., an AOM). In another embodiment, the linear diffuser can be moved by a moving part such that the optical properties and vibration behavior of the diffuser in combination form the collimated beam into a single light beam. In such a configuration, a field lens can be further included between the oscillating laser source and the linear diffuser or immediately after the linear diffuser. Such a field lens can also be integrated with the linear diffuser, for example, the field lens can be created in a hologram that can also serve the function of the linear diffuser. The MEMS mirror can be configured to oscillate in each of two substantially orthogonal degrees of freedom, so that a planar fan is generated along a first (fast) scan direction and the planar fan moves over the work surface along a second (slow) scan direction. In various embodiments, the device for generating the planar fan can be employed to configure / build a laser displacement sensor (DS). Such a DS can be operatively connected to a vision system processor.In some embodiments, the planar fan generating device may include optics having one or more of a processed linear diffuser, a hologram, and a cylinder array, and may be configured to project the planar fan with a non-continuous pattern. Such a non-continuous pattern may define one or more of dots, light beam segments separated by non-illuminated gaps, or other suitable patterns. In some embodiments, light is captured from at least a portion of the illumination formed by the planar fan projected onto a work surface with a sensor. The sensor may generate image data from the captured light. Such image data may be processed / used to perform measurements and / or inspections on an area of ​​the work surface. The work surface may form at least a portion of the measurement target.

[0009] In another embodiment, a system and method are provided for reducing at least one of speckle and sparkle effects in radiation projected onto a surface. The system and method employ a collimated light source and an optical component capable of producing a fan of light at a predetermined angle(s) on either side of a central optical axis. A linear diffuser through which the beam or fan passes is located between the optical component and a work surface. The optical component may include one or more of a MEMS mirror, a solid-state deflector, and a Powell lens. The collimated light source may be a laser.

[0010] In another embodiment, a system and method for scanning a surface to quantify 3D profiles is provided, with the advantage that the profiler and the object can remain relatively stationary during scanning. A vision system camera can be configured to image the surface along its optical axis. A parallel light source can also be used remotely to project a beam at an angle non-parallel to the optical axis. A MEMS mirror can receive the beam from the parallel light source and project it onto the surface at an angle non-parallel to the optical axis. The mirror control means can drive / oscillate the MEMS mirror according to two or more orthogonal degrees of freedom, thereby (a) generating a fan light along a first direction within one or more predetermined angular ranges on either side of a central optical axis, and (b) moving the fan along a second direction, causing the fan to scan the surface. A linear diffuser through which the fan passes is placed between the MEMS mirror and the surface. For example, a polarizing beam splitter-1 / 4 λ optical retarder can be placed in the optical path of the parallel light source. A cylindrical lens may be positioned in the optical path. A mirror control means may be configured to oscillate the MEMS mirror in a first direction at a first velocity and in a second direction at a second velocity slower than the first velocity. The vision system camera may include an imaging sensor having a first optical plane and a lens assembly having a second optical plane non-parallel to the first optical plane. The first and second optical planes may each be oriented according to the Scheimpflug principle with respect to a plane defined by the fan.

[0011] In another aspect, the disclosed technology can be implemented as an illumination system for reducing speckle in light reflected from an illumination target. The system includes a light source configured to emit coherent light and a linear diffuser disposed in an optical path between the illumination target and the light source, the linear diffuser configured to disperse (scatter, diffuse) the coherent light into diffuse light that spreads along one dimension across at least a portion of the illumination target. The linear diffuser has an exposure time associated with the illumination target being illuminated by the diffuse light, thereby forming a planar fan light that does not substantially spread in a direction perpendicular to the one dimension. The system further includes a beam deflector disposed in the optical path between the light source and the linear diffuser, and a control means coupled to the beam deflector. The control means operates the beam deflector such that the coherent light is projected onto the beam deflector to sweep through a plurality of positions on the linear diffuser during an exposure time during which the illumination target is illuminated by the diffuse light, and the plurality of positions on the linear diffuser span a distance such that light reflected from an intersection of the planar fan light with the illumination target is provided with a sufficiently uncorrelated speckle pattern at the image sensor to be non-coherently added when imaged by the image sensor during the exposure time during which the illumination target is illuminated by the diffuse light.

[0012] Each of the above and other embodiments may optionally include one or more of the following features, either individually or in combination. In some implementations, the light source may include a laser. In some implementations, the beam deflector may include a microelectromechanical system (MEMS) mirror. In some implementations, the beam deflector may include an acousto-optical modulation (AOM) device.

[0013] In some implementations, the system may include a cylinder lens located in the optical path between the linear diffuser and the beam deflector, which may act as a field lens to increase efficiency by concentrating all of the coherent light directed at the linear diffuser, and in some implementations, the system may include a cylinder lens and a linear diffuser may be placed between the beam deflector and the cylinder lens, which may be configured to act as a field lens to increase efficiency by concentrating all of the diffuse light directed at the target.

[0014] In some implementations, the linear diffuser may include a textured diffuser with a flat-top intensity profile along one of the faces described above. In some implementations, the linear diffuser may include a chirped diffraction grating with a free spectral range (FSR) that allows the spacing of the diffracted rays in the planar fan of light to vary with the sweep angle of the coherent light projected onto the linear diffuser. In some implementations, the linear diffuser may include a hologram or a cylinder array.

[0015] In one implementation, the linear diffuser is stationary relative to a base of the beam deflector, and the control means is configured to operate the beam deflector to periodically sweep the coherent light left-right-left, etc., relative to the linear diffuser, such that during an exposure time in which the target is illuminated by the diffuse light, the coherent light is directed through either the left-right or right-left half of the left-right-left sweep.

[0016] In another aspect, the disclosed technology can be implemented as a laser displacement measurement system. Such a system includes a vision system processor, a camera component coupled to the vision system processor, a laser beam component coupled to the vision system processor and configured to project coherent light, a beam deflector positioned to receive the coherent light, a control means coupled to the beam deflector, and a linear diffuser positioned in an optical path between an object to be illuminated and the beam deflector. The control means is configured to operate the beam deflector such that the coherent light is projected onto the beam deflector and sweeps through a number of positions on the linear diffuser. The linear diffuser is configured to receive the coherent light from the beam deflector at a number of positions and to diffuse the coherent light to a diffuse light. The diffuse light spreads along a plane across at least a portion of the object to be illuminated. The linear diffuser has an exposure time associated with the diffuse light illuminating the object to be illuminated. The diffused light forms a planar fan light that does not generally spread along a direction perpendicular to one of the faces, and the locations on the linear diffuser span a distance across the linear diffuser such that light reflected from an intersection of the planar fan light with an object is provided with a sufficiently uncorrelated speckle pattern at the image sensor to add non-coherently when imaged by the image sensor during an exposure time during which the object is illuminated by the diffused light.

[0017] Each of the above embodiments and other embodiments may optionally include one or more of the features described below, either alone or in combination. In one implementation, the linear diffuser may be stationary relative to a base of the beam deflector, and the control means is configured to operate the beam deflector to periodically sweep the coherent light left-right-left... relative to the linear diffuser, and the control means is configured to direct the coherent light through either the left-right half or the right-left half of the left-right-left sweep during an exposure time during which the target is illuminated by the diffuse light.

[0018] In some implementations, the linear diffuser may include a textured diffuser with a flat-top intensity profile along a surface as described above. In some implementations, the linear diffuser may include a cylinder array. In some implementations, the linear diffuser may include a hologram configured to project the planar fan of light onto the illumination target in a non-continuous pattern. The non-continuous pattern may include, for example, one or more dots or line segments separated by non-illuminated intervals. In some implementations, the linear diffuser may include a chirped grating having a free spectral range (FSR) such that the spacing of the diffracted beams in the planar fan of light varies with the sweep angle of the coherent light projected onto the linear diffuser.

[0019] In some implementations, the beam deflector may include a microelectromechanical system (MEMS) mirror, and in some implementations, the beam deflector may include an acousto-optical modulation (AOM) device.

[0020] In some implementations, the system may include a cylinder lens located in the optical path between the linear diffuser and the beam deflector, which can function as a field lens to increase efficiency by concentrating all of the coherent light directed toward the linear diffuser, and in some implementations, the system may include a cylinder lens, with the linear diffuser located between the beam deflector and the cylinder lens, where the cylinder lens is configured to function as a field lens to increase efficiency by concentrating all of the diffuse light directed toward the target.

[0021] In some implementations, the laser beam component may include a laser.

[0022] In some implementations, a camera component can be configured to capture light reflected from an intersection of the planar fan light with an object and generate image data from the captured light, where a vision system processor is configured to receive image data from the camera component and process the image data to measure, inspect, or both an area on the object. In some implementations, the camera component can include an imaging sensor having a first optical surface and a lens component having a second optical surface non-parallel to the first optical surface. The first optical surface and the second optical surface can each be oriented with respect to the planar fan light according to the Scheimpflug principle. [Brief description of the drawings]

[0023] In the following description, reference is made to the following accompanying drawings: [Figure 1] 1 is a schematic perspective view of a laser displacement sensor (DS) system that captures images of an object as it moves relative to itself in a scanning direction, employing a speckle reduction system according to an example embodiment; [Diagram 2] FIG. 2 is a side perspective view of a laser source with a speckle reduction configuration (despekle configuration, anti-speckle configuration) according to the example embodiment of FIG. 1. [Diagram 3] FIG. 3 is a front view of the laser source of FIG. 2. [Figure 4] FIG. 1 shows a movable laser (beam source) delivering a periodically oscillating beam to the laser source. [Diagram 5] FIG. 2 is a diagram illustrating the relative positions between components of a light beam generating system and a work surface onto which the light beam is projected. [Figure 6] 1 illustrates components of a beam generating system according to an exemplary embodiment, capable of generating a segmented beam shape; [Figure 7] FIG. 7 is a diagram showing an example of a dotted line shape generated when the configuration in FIG. 6 is adopted. [Figure 8] 7A and 7B are diagrams showing examples of a plurality of bar shapes generated when the configuration of FIG. 6 is adopted. [Figure 9] FIG. 13 is a side cross-sectional view of an exemplary DS system according to another embodiment, in which the laser beam generator includes both a speckle reduction configuration and a scanning configuration, and uses a MEMS mirror that can rotate about each of two substantially orthogonal axes. [Figure 10] 10 is a side perspective view of a laser beam generator with a despeckle single beam scanning configuration in accordance with the example embodiment of FIG. [Figure 11] FIG. 11 is a front view of the laser beam generator of FIG. 10 showing an example working section. [Figure 12] 1 is a schematic diagram illustrating multiple light rays (shown as solid lines) simultaneously projected onto a surface and their positions after they have been moved by scanning. [Figure 13] FIG. 10 is a schematic diagram showing a side-by-side comparison of an example laser beam image produced by the exemplary DS system of FIG. 9 with a speckled beam produced using prior art optical products / components. [Figure 14] FIG. 10 is a flow diagram showing the general procedure for operating the DS system of FIG. [Figure 15] FIG. 1 illustrates a generalized beam generating system having a moving part that drives a beam generator, such as a linear diffuser that oscillates in a manner according to an embodiment. [Figure 16]FIG. 1 illustrates a light generating system according to any of the configurations or embodiments described above, depicting a light beam projected at a distance for various applications. [Figure 17] FIG. 1 illustrates a beam generation system used to provide illumination in 2D imaging applications, where the illumination is provided as a discrete beam or a scanning beam to fill the working area of ​​the camera. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] I. Vision System Implementation

[0025] As a non-limiting example, FIG. 1 shows an example vision system 100 including a laser displacement sensor (DS) component 110, directed to image an object 120 (sometimes referred to as a "part"). The DS component 110 is housed in a single housing 112 so that it can be placed at a suitable location relative to the imaged scene. In alternative embodiments, the displacement sensor may include separate subcomponents. In an example implementation, the object 120 and the displacement sensor 110 are in relative motion (indicated by the double arrow MY) with the displacement sensor 110 and / or the object 120 moving (in the direction of the scanning motion) along one or more axes of a relative coordinate system 124 (note that in this example, the scanning motion is along the physical y-axis). In a typical configuration, the object 120 is placed on a motion conveyance 130 (shown in dashed lines). The motion means 130 is adapted to provide motion data from an encoder or other device operably coupled to the drive train 132 in a manner apparent to those skilled in the art.

[0026] As will be described in more detail below, the system and method may also be used on images that are captured and stored for further processing, and such images may be transferred for processing by the system and method (i.e., the vision system tools associated with the filtering process) without a processor connected to the camera components or other image capture configuration.

[0027] As an example, the object 120 may be a structure having a surface 140 that generally defines a three-dimensional (3D) contour, e.g., where the height (i.e., displacement along the physical z-axis) may vary with respect to the x- and y-axes. Note that this is only one example of a wide variety of possible surface shapes, and is merely a useful example that follows the principles of the exemplary embodiments of the system and method. Another example may be one in which the perimeter defines a more complex boundary and has different / additional features.

[0028] The DS assembly 110 includes a laser beam assembly 150 capable of projecting a coherent beam 152. The beam 152 is directed to a movable beam deflector 153 (e.g., a mirror, described in more detail below). In this embodiment, the deflector 153 deflects the central axis of the beam (dashed line 170) by approximately 90 degrees. Note that the angle of 90 degrees (to the right) shown here is merely exemplary, and the angle of the beam deflection can vary depending on the system configuration and other desired design criteria. The deflector 153 also includes a drive mechanism or other mechanism 155 (including solid-state structures described below) that allows the deflector 153 to reflect the beam laterally in a periodic pattern (e.g., left to right). In some embodiments, the drive mechanism 155 allows the deflector to pivot about an axis through a + / - angle range. The reflected beam periodically moves back and forth, resulting in a sweeping fan 154 that is centered about a fan axis 170. This fan of beams passes through an optical arrangement that includes a cylindrical lens 156 and a linear diffuser 157, which (optional in other embodiments) directs a planar fan 158 in the desired configuration toward the object 120 and the surrounding scene. As will be described in more detail below, the diffuser 157 and movable deflector 153 create a planar fan 158 of diffuse light that has a substantially Gaussian beam with negligible out-of-plane thickness and that intersects the imaged scene (e.g., the object 120 and the moving means 130 in this embodiment) along an illumination profile 159 that is effectively speckle-free and has a uniform thickness regardless of the in-plane displacement of the illumination profile.

[0029] As mentioned above, the illumination contour 159 (also referred to as the "illumination line") is defined along the physical x-axis (i.e., transverse to the scanning motion direction MY). In this embodiment, the planar fan 158 is approximately perpendicular (or substantially perpendicular) to a reference plane, such as the physical xy plane of the motion means 130 and / or the surface 140 of the object 120. The displacement sensor assembly 110 also includes a camera assembly 160 (shown as a dashed box). The camera assembly 160 generally includes a lens / optical assembly 162 and an imaging element 164. The lens / optical assembly 162 can be arranged in a known Scheimpflug configuration (or other suitable optical configurations as would be understood by one of ordinary skill in the art). The imaging element 164 has an array of photosensitive pixels that defines a predetermined resolution. The camera assembly 160 generally defines an optical axis OA. The optical axis OA will intersect the object 120 within the area of ​​the illumination line 159. The camera optical axis OA is angled (e.g., acute) A, non-parallel, with respect to the plane of the planar fan 158 (and associated axis 170). This means that any height change / displacement along the physical z-axis along the illumination line 159 along the physical x-axis can be captured by the camera assembly 160 as a position change (along axis YI in the image), represented here as an image ray 171 in a two-dimensional (2D) image 172. Such a 2D image can generally be displayed in an exemplary (and optional) user interface display 174.

[0030] Note that the arrangement of axes x, y, z shown here is conventional, and it is clear that other representations of relative directions (such as polar coordinates) are anticipated. As mentioned above, rotational motions around a given axis are also represented, e.g. the curved double arrow Rx represents rotation around the physical x axis.

[0031] The image sensor 164 is operatively interconnected to a vision system processor 180, which in this embodiment is contained within the housing 112 of the displacement sensor 110. In alternative embodiments, some or all of the vision system processor components and / or processes may be located away from the housing (e.g., in an interconnected tablet, laptop, or PC that may be associated with a display 172). As will be described in more detail below, in accordance with an exemplary embodiment, the vision system processor 180 may perform a displacement sensing process 182. The processor 180 may also receive relative motion signals from the motion means 130 or another movable device (such as a platform or manipulator that holds the displacement sensor and / or the object). Images may be obtained in association with such motion signals to register the illumination line 159 with its physical location (actual position) in the scene. The images may then be stored in a suitable memory or storage location 188 for further transmission and / or analysis. It should be noted that the use of DS components that move relative to the object being inspected is merely an example, and that the beam generating system according to the present embodiment can be used in a wide variety of applications. For example, DS components of the type described above may be employed in a static configuration for various applications, for example to generate a static beam profile or cross section (without relative motion) for a stationary object. The reduced speckle beam that can be generated by such an embodiment has the advantage of increasing the accuracy of the measurement.

[0032] The DS component 110 and other devices may include / incorporate suitable vision system tools and processes / processors 183, such as edge detectors, line finders, blob analyzers, calipers, and the like. These tools and processes / processors 183 may analyze the 3D images provided by the imager 164 and derive results based on the analysis. By way of non-limiting example, the image data (i.e., range images or 3D point clouds) and / or analysis results may be passed to downstream data processing devices and processes for use in various production activities, such as inspection, quality control, object manipulation, assembly, and the like.

[0033] Other modules of the processor 180 may include a mirror / deflector control process / processor 190 interconnected to the beam deflector drive means 155. The control means 190 may drive the deflector at an appropriate periodic rate (frequency) based on the imaging frame rate of the imager such that in each frame, a series of instances of the illumination line 159 corresponding to the complete trajectory of the beam 152 on the linear diffuser 157 are captured.

[0034] II. General purpose despeckled beam configuration

[0035] The above-described DS embodiment provides an implementation where the despeckled beam can be beneficially used to improve the performance of a vision system. This beam generation configuration can be employed in a variety of applications, such as range finders, 3D topographical scanning systems, laser levels, and other forms of triangulation systems. Figures 2 and 3 show a generic configuration of a laser generation system 200 that can be used to despeckle the illumination beam 260 to perform beam displacement measurements with greater accuracy and consistency.

[0036] For example, generator 200 includes a laser 210 of suitable power and wavelength, which may be a diode-based solid-state device or another suitable unit having a relatively compact design and form factor, which necessarily projects collimated light 212 of any suitable wavelength (e.g., near-visible, UV, IR, etc.) that is temporally and spatially coherent.

[0037] The incident beam 212 is directed along an incident path to a beam deflector 220 (a mirror / reflective surface of any configuration or a solid sweep generator). The beam deflector 220 reflects all or nearly all of the beam 212 towards an output path shown centered about an axis CA. As shown, the output path axis CA is at an angle AL, which is 90 degrees (perpendicular) to the incident beam 212. In other implementations, the angle AL can vary. The beam deflector reciprocates (e.g., rotates) along one axis. The beam deflector 220 may include any mechanical or solid structure that causes the reflected path of the beam to deviate from the central axis CA. For example, the beam deflector 220 can include a microelectromechanical system (MEMS) mirror, a galvanometer mirror, an acousto-optical modulator (AOM) device, or other device, or a material such as lithium niobate (LiNIBO3), or some other material, to sweep (double arrow 310 in FIG. 3) the reflected output beam (shown as a stripe 320 at one end of the swept fan 230) into a planar swept fan 230.

[0038] In this embodiment, the sweep of the beam deflector 220 (represented by a curved double arrow 224) is oriented around a pivot axis 222 about which the incident beam 212 is centered. A drive circuit and / or mechanism 240 (driver) is operatively connected to the deflector 220. The drive circuit and / or mechanism should be appropriate for the technology used to implement the deflector and should be apparent to one of ordinary skill in the art. As described below, these drivers and deflectors together can periodically sweep the beam and thereby shape the beam trajectory (forming a sweeping fan 230) with a speed and amplitude (side to side) large enough to provide a sufficiently random speckle pattern of the illumination line 260 within one unit of exposure time (e.g., one image frame). In this way, the speckle in the imaged pattern is smoothed out to produce a visually smooth line. For example, by moving beam 320 at a rate of at least 1 / 2 cycle per frame, images of the entire length of illumination line 260 within scene 290 (or 130 + 140) can be captured by an imager (such as imager 160). If the scan were shorter, such as 1 / 4 cycle (out of left-right-left cycle 310) per frame, such as left-center or center-right, the quality of the speckle smoothing would be degraded. For example, the speckle smoothing quality for the 1 / 4 cycle scan described above would be 71% (1 / √2) of the quality of the speckle smoothing for the 1 / 2 cycle scan described above.

[0039] System 200 may also include an optional cylinder lens 250 or similar optical structure, which acts as a field lens and can improve efficiency by concentrating all of the light from swept beam 320. Lens 250 provides a more uniform illumination intensity and speckle smoothing at target 290 over the entire length of illumination line 260. Lens 250 is optional and may be omitted in other embodiments. In other embodiments, the function of such a lens may be incorporated as a feature in a hologram or line generator. As described below, the term "line generator" as used herein refers to a linear diffuser (e.g., a feature linear diffuser with a specific intensity profile designed to diffuse the incoming light so that it spreads in only one plane, a hologram, a chirped grating, and / or a cylinder array) or a linear diffuser combined (e.g., integrated) with other components that can cooperate to form a planar fan of light.

[0040] The system 200 includes a beam generator 270, which may include a linear diffuser of conventional or custom design. For example, the beam generator 270 may be implemented as a machined diffuser with a "flat-top" intensity profile. It may be used to provide diffusion primarily in one direction (typically along the direction of the illumination beam 260) or, as envisioned in this embodiment, to provide diffusion in only one direction. By way of non-limiting example, the linear diffuser may be an Engineered Diffuser™ Line (EDL) with suitable parameters available from RPC Photonics, Inc., Rochester, NY. For example, a model "EDL-40-A" is designed to have a line intensity distribution of + / -20 degrees, a relatively constant (flat-top) intensity within this angular range, and a rapid drop to zero intensity past either side of the flat-top. The scattering from this linear diffuser is relatively uniform within the opening angle. Other types may have smaller or larger line intensity distributions (e.g., + / - 60 degrees, or a total of 120 degrees). The scattering of this diffuser is specifically characterized by being exclusively in one degree of freedom, with almost no scattering across this one degree of freedom. This characteristic ensures that the illumination line 260 does not thicken or spread, and the thickness of the fan light perpendicular to the plane of the fan light is essentially equal to the Gaussian profile of the laser used. Note that if the laser beam were stationary in the linear diffuser 270 (whether textured, holographic, or otherwise), the linear diffuser 270 would not only produce obvious objective speckle on the object 290, but would also produce other scattering and reflection artifacts that would adversely affect the uniformity of the illumination profile 260, and all of these would be stationary and have the same appearance to the observer. In contrast, subjective speckle, which is the subject of the techniques of this disclosure, varies for different observers, apertures, and positions.The sweep 310 of the beam 320 traverses the diffuser 270, smoothing out these objective speckles and other artifacts into (i) an intensity profile in the direction of the illumination line at the object 290, and (ii) a beam profile substantially equal to the profile of the original laser beam 212 and perpendicular to the sweep direction (a profile that is constant with respect to the sweep direction).

[0041] In another embodiment, the beam generator 270 may include a holographic diffuser or other type of diffuser that can split the beam of light passing through it into multiple beams along the primary direction (line 260). This is shown in FIG. 3 as the beam 320 is split by the beam generator 270 into multiple beams 330 that are distributed over at least a portion of the working area (e.g., the length of the line 260). In the example shown in FIGS. 2-3, the combination of the lens 250 and the beam generator 270 is arranged and configured to cause the multiple beams 330 to form a fan-shaped diffused light pattern 330F. This diffused light pattern 330F will intersect with the object 290 along the initial state of the line 260. As the beam 310 is swept through its path, the pattern is maintained as shown as beam 340 and beam 350. For example, beam 340 may form another fan-shaped scattered light pattern 340F that intersects object 290 along another state of illumination line 260, and beam 350 may form yet another fan-shaped scattered light pattern 350F that intersects object 290 along yet another state of illumination line 260. This effect results in a consistent and accurate cumulative image of illumination line 260 by smoothing out the speckle within each scattered state of illumination line 260. In other words, all points of the imaged state of illumination line 260 may be non-coherently summed over an exposure interval (e.g., an image of the complete line).

[0042] The sweep angle Θ of the sweep fan 230 on either side of the axis CA may vary based (in part) on the size of the beam generator 270 and the sweep angle 224 of the beam deflector 220. As a non-limiting example, the angle Θ may be in the range of 20-30 degrees (e.g., in a MEMS implementation), with the illumination line 260 defining a working area of ​​approximately 1 meter. As a further example, the beam deflector 220 may have a mirror surface (e.g., in a MEMS implementation) defining a diameter of approximately 1.0 millimeter. For example, the MEMS may be configured to operate at its natural frequency. By way of example, the natural frequency of such a MEMS mirror may be in the range of approximately 20 KHz. It is noted that the MEMS implementation may be fabricated by a suitable fabricator according to a user specification in a manner obvious to one skilled in the art.

[0043] While movable or solid beam deflectors have been described, it is also conceivable to periodically drive or deflect the beam source, for example via coaxial components (such as dispersive and / or refractive structures). For example, a laser diode can be integrated with a voice coil to oscillate along a degree of freedom. That is, it is generally conceivable to generate the sweeping fan 230 by providing a periodically oscillating beam 320 from the beam source in one direction or along one plane. When such an oscillating beam 320 passes through the beam generator 270, it spreads according to the beam generator 270's included angle through inherent scattering along the degree of freedom, forming a planar fan 280 as the fan-shaped scattered light pattern 330F, ..., 340F, ..., 350F.

[0044] In the arrangement 400 shown in Figure 4, a laser 410 is driven by suitable drive circuitry or control means 430 around axis 420 to oscillate periodically (represented by curved double arrow 422). The laser 410 emits a collimated beam 441, which may be mounted on a flexure, voice coil, or other component to move the collimated beam along degrees of freedom relative to the central axis 442 to trace a planar (sweeping fan) pattern 440. In another embodiment, the laser may be mounted with coaxial optics (such as a prism and / or lens) to oscillate the collimated beam 441 periodically. The oscillating beam 441 tracing the planar pattern 440 is transmitted to a light beam generator 450. As mentioned above, the term "line generator" refers to a linear diffuser (designed to spread the incoming light in only one plane) or a linear diffuser combined (e.g., integrated) with other components that can cooperate to form a planar fan-shaped light pattern. Thus, the beam 441 is scattered along one degree of freedom to form a corresponding state of the fan-shaped light pattern 451, which is projected onto the work surface 460 as a line segment 461. The set of states of the line segment 461 generated by the beam 441 tracing the planar pattern 440 overlap, resulting in a speckle reduction line 462. The speckle reduction line 462 is the intersection of the planar fan of the scattered light 480, which is generated by the overlapping set of states of the fan-shaped light pattern 451 intersecting with the work surface 460. A field lens or other diaphragm structure may be included coaxially between the laser 410 and the beam generator 450 or may be formed within the beam generator. In alternative embodiments, the lens may be omitted. It is noted that the term "oscillating laser source" should be interpreted broadly to include a movable laser and / or its coaxial optics, or a laser in combination with a beam deflector as described above, or a combination of these components.

[0045] III. Distance and Component Placement

[0046] It will be apparent that the above-mentioned components of the beam generating system 200 or the beam generating system 400 (laser, beam deflector or other mechanism for oscillating the beam, optional lenses and beam generators) may be housed in one or more housings / enclosures in various combinations and relationships that are precise and stable to provide the form factor and function required for the desired task. The enclosures may be made of any suitable material, such as polymers (polycarbonate, acrylic, etc.) or metals (aluminum alloys, steel, magnesium alloys, etc.). The distance between the components and the component sizes may be determined in a manner apparent to one of ordinary skill in the art based on the working area according to the length of the beam and the working distance from the beam deflector 270 or the beam deflector 450 to the working surface.

[0047] FIG. 5 is a schematic diagram of an example beam generating system 500, in which the laser and beam deflector (more generally, the oscillating laser source) are housed in a single unit 510 (such as a circuit board) and interconnected to a power source. The laser can sweep + / - Θ degrees about a central axis 520 at a given frequency F that can be changed based on communication between the system's control means and associated interfaces. The oscillating laser source 510 is separated by a distance DL from an (optional) cylindrical lens and beam generator (linear diffuser) component 530. The values ​​of Θ and DL determine the minimum width WLG required for component 530, i.e. WLG = 2tanΘ*DL. The (optional) lens and beam generator component 530 can be separate or can be combined with the laser source 510 in a single housing (as shown as dashed box 540). In another embodiment, the lens and the beam generator may be spaced apart from each other along the axis 520. In general, the working distance DO between the beam generator and the working surface 550 can vary depending on the application, as can the desired maximum length LL of the illumination line and the geometry of the lens and beam generator components 530. The length LL may also be determined based on the beam generator's inherent scattering divergence angle α along the degrees of freedom, as discussed above. For example, with a desired maximum length LL = 100 mm and a working distance DO = 300 mm, the beam generation system 500 may be designed with (i) a beam deflector (such as a MEMS mirror) with a resonant frequency of 20 kHz and an optical scan angle θ of + / - 15 degrees, and (ii) a beam waist diameter of 500 microns and 1 / e in the sweep direction. 2The beam generator assembly 530 may include a laser (e.g., laser 150, 210) with a minimum width WLG = 10 mm, which is located a distance DL from the laser source 510 that is sufficient for the beam deflector (e.g., beam deflector 153, 220) to sweep the laser beam to the distance WLG. If the required beam deflector 530 has a 40 beam diameter scan with a 2θ of 30° and a WLG of 20 mm, then the required distance DL = (WLG / 2) / (tan(15°)) = 37 mm. Also, if the sweeping laser beam has a frequency F (e.g., 20 kHz), then the minimum imaging time (e.g., exposure time) for maximum speckle reduction is half the period of the MEMS mirror (50 μs in this example), i.e., Δt = 25 μs. The total scattering angle α of the diffuser is chosen so that the scattered beam formed by the linear diffuser 530 from the stationary laser beam at least irradiates the total length of the beam LL at the working distance DO. In the above example, α = 2*(atan((LL / 2) / DO)) = 18.9°. A scattering angle of 20° or more for the linear diffuser 530 is considered sufficient. If no field lens is used, this scattering angle is doubled to allow continuous illumination and maximum speckle reduction. If we use a field lens and place it next to the linear diffuser, we simply place a cylinder lens with focal length (f) which can be calculated from the conjugate lengths s1 = DL = 37mm and s2 = DO = 300mm, so we use the lens equation 1 / s1 + 1 / s2 = 1 / f to calculate the focal length, where f = 32.9mm, making the lens length approximately equal to the diffuser length WLG.

[0048] IV. Optical Effects

[0049] The arrangement of components according to the present disclosure can be used to generate a beam of light that can be usefully reduced speckle and can also project a variety of shapes. FIG. 6 shows an example of a beam generator 600 in which a laser and deflector (or other motion generating components) 610 generate a sweeping fan of beams 620 as described above. The fan 620 is transmitted through an optical component 630 that can define any combination of lens and linear diffuser functions. As described above, the optical component 630 can include (for example) a cylindrical array or diffractive elements and / or holograms to generate special beam effects. For example, such a diffractive element can be a chirped grating with a free spectral range (FSR) that can vary the spacing of the diffracted beams in a planar fan 640 to vary the sweep angle of the coherent light 620 projected onto the linear diffuser 630. As shown, the scattered light beam 640 can project a non-continuous line 650 along the axis of the beam, consisting of line segments 652 separated by non-illuminated intervals 654, shown as dashed lines. This is only one example of the variety of effects that can be produced. For example, the length of the line segments can be varied along the axis (such as by using a hologram).

[0050] In Figure 7, the beam generating system 600 can be used to generate a dotted pattern 700, which is a set of appropriately spaced dots. Similarly, in Figure 8, the beam generating system 600 can be used to generate a linear feature 800, which is made up of parallel lines 810 and 820. Various optical components (such as custom designed holograms) (as will be apparent to those skilled in the art) can be used to split the projected fan into multiple lines. These lines can be split into dots, dashes, etc., as described above.

[0051] V. Other Surface Effects

[0052] While the principles and embodiments described above relate to the phenomenon of speckle, the following application is to reduce undesirable optical effects associated with surface finishes from which radiation reflects. For example, surfaces with small reflective facets (such as machined, grained, bead-blasted, staking, bright or metallic paint finishes) are difficult to accurately measure with conventional laser sources. Conventional laser sources are traditionally generated from point sources and are prone to random bright spots or flashes that can saturate the imager (or other light receiving components) and degrade the quality of the captured / detected light. This phenomenon is also referred to as "sparkle" and has been empirically shown to cause optical defects similar to the speckle described above. Thus, for the purposes of this disclosure, the term "speckle" should be broadly interpreted to include flashes. It should be noted that flashes can result from any type of light reflection, whereas speckle is specific to the reflection of coherent light. The implementation of the above mentioned light beam generator (e.g. linear diffuser) also significantly reduces the glint phenomenon. In this respect, the role of the diffuser is similar to that of a conventional diffuser for daytime lighting on cloudy days, but in this case the scattering effect generated by the light beam generator occurs only in a single plane (parallel to the illumination beam), so that the quality of the light beam is not degraded even on surfaces prone to glints, thus improving the quality of the captured light beam.

[0053] By way of example, reduction of speckle in a light source generating an illumination or similar beam can be achieved using various configurations as described above, such as a beam generator including a linear diffuser, hologram, and / or diffractive array in combination with a light source (coherent or other collimated light source) that transmits the beam to a movable deflector (such as a MEMS or solid-state device), or alternatively, by transmitting the beam to conventional fan-generated optics (such as a Powell lens) and then through the beam generator.

[0054] VI. How to Perform a Scan

[0055] FIG. 9 shows an embodiment of a DS system 900 in which a planar fan 910 is generated and projected onto the scene / object, and scanned along a direction approximately perpendicular to the planar fan. This means that scanning over a given working distance does not require a separate motion generator. The processor arrangement is similar to that described with respect to FIG. 1 (vision system processor 180), while mirror control 190 (as well as sensing process 182 and / or vision tools) are used to enable integrated scanning, as described below. In one embodiment, a commercially available diode-based laser (e.g., about 40 mW) may be used. The projected light may be red or of another desired wavelength.

[0056] The DS system 900 includes a camera assembly 920 having an optical package (lens assembly) 922 defined along an optical axis OA1, and an imager 924. By way of non-limiting example, such an optical package 922 is modeled as a DS 1050 displacement sensor available from Cognex Corporation of Natick, Massachusetts. The imager 924 in this example embodiment is a 2D sensor capable of acquiring an image of a working area defined by two orthogonal axes (described in more detail below). In particular, the lens surface (dashed line OP) of the lens assembly 922 is oriented at an acute angle AOP with respect to a generalized plane of the imaged scene (represented by a straight line PS), the angle ranging from approximately 20 to 30 degrees. The imaging plane (shown by dashed line SP) of the imager 924 is oriented at an acute angle ASP (with respect to the scene plane PS) that is generally narrower than the optical angle AOP, which may be in the range of, for example, 10-15 degrees. The angles AOP and ASP are selected such that light rays within the working area are imaged by the camera assembly 920 generally in accordance with the Scheimpflug principle, such that the light rays seen by the imager 924 are relatively constant in thickness between the near and far ranges of the working area.

[0057] The DS system 900 can be housed in a suitable housing 930, with the appropriate spatial relationship between the components, and the system can be mounted to the scene using brackets or the like. The housing 930 contains a solid-state laser component (or other mechanism capable of projecting similar coherent light). In this embodiment, the laser emits a pencil-like beam 940 of suitable thickness, directed downwards towards a polarizing beam splitter 942, which is shown to reflect the polarized beam 944 at a 90 degree angle. Alternative arrangements may include a different size laser, different housing form factor, or the laser may be directed directly towards a polarizer, beam splitter component 950, or other structured light / conditioning component. The polarized beam 944 is directed to a beam splitter assembly 950 with a beam splitting mirror 952, which in turn directs a reflected beam 954 to an upward wave plate 956 (e.g., a 1 / 4 λ wave plate). The upward reflected beam 954 is projected onto a MEMS mirror 960. The MEMS mirror 960 is driven by a printed circuit board (PCB) 962 mounted on an adjacent plate assembly 964. The PCB is controlled as part of the processor-based mirror control described above. The adjacent plate assembly allows the fabricator to fine-tune the mirror tilt (e.g., by using screws) to properly orient the mirror. The entire mirror mounting arrangement 966 is fixed within the housing 930 and is generally vibration-free and operable with a stable relative angle between the optical axis OA1 and the illumination line.

[0058] In particular, the MEMS mirrors in this embodiment may include multi-axis (two degrees of freedom) designs, including, by way of non-limiting example, those available from Opus Microsystems, Taiwan. Some models (such as the OP-6111) have fixed scan frequencies of 22,000 Hz in the fast direction (+ / -20 degrees) and 1,400 Hz in the slow direction (+ / -15 degrees). Soon-to-be-commercially available mirrors (such as the OP-6200) support a fast scan frequency of 18,500 Hz (+ / -22 degrees) and a slow scan frequency (+ / -12 degrees) that is controllable using a voltage waveform signal. The angular range of operation for each pivot axis described above is merely exemplary, and in practice the DS working area may be located within a subset of the full angular range.

[0059] The beam (dashed line 970) reflected from the MEMS mirror 960 passes through the wave plate 956 and through the polarizing beam splitting mirror 952. The beam then passes through (for example) a cylindrical lens / linear diffuser component 980, which uses the principles of the present disclosure to diffuse the beam 970 into the desired planar fan 910, as described above and below. In particular, the combination of the polarizing beam splitter 942 and the λ / 4 wave plate 956 effectively eliminates all back reflections in the optical path. The optical path can also include (in appropriate locations) thin cladding to attenuate light that strays from the MEMS mirror, as well as light that reflects off the surrounding reflective surfaces of the MEMS mirror, the front surface of the λ / 4 wave plate 956, and the back surface of the polarizing beam splitter 952. These features greatly reduce the geometry requirements of the system during manufacturing.

[0060] FIG. 10 illustrates in more detail the principle of operation of a scanning laser configuration according to the DS system 900 of FIG. 9, using an example DS system 1000. As shown, a laser source 1010 projects a beam 1012 along an axis onto a turning (MEMS) mirror element 1020. The mirror element 1020 oscillates (curved double arrows 1022, 1024) about two orthogonal axes 1030, 1032 (typically oriented at right angles to each other). Rotation of the mirror element 1020 about axis 1032 typically produces a fan pattern, also referred to as a swept fan. The swept fan is represented by three straight lines 1050, 1052, 1054. The characteristics of the swept fan are similar to those described for the swept fans 154, 230. The laser, now in the form of a swept fan, is directed towards an (optional) cylindrical lens 1070 and a linear diffuser 1072. The combination of lens 1070 and diffuser 1072 creates a corresponding fan-shaped diffused light pattern 1080F for each of the three lines 1050, 1052, 1054 (shown as lines 1080). In this manner, the swept beams 1050-1054 effectively project a planar fan 1085 (formed from a series of instances of the fan-shaped diffused light pattern 1080F) onto a surface 1090, so that the intersection of the planar fan with the surface defines a despeckled illumination line 1082. The despeckled illumination line 1082 is created by oscillating the mirror 1020 in the fast scan direction (double arrow 1092). As mentioned above, in some embodiments, the fast scan can be performed at frequencies in excess of 20,000 Hz. The mirror assembly 1020 can also be oscillated in a slow scan direction about an axis 1030 (double arrow 1094), typically at frequencies between 1,000 and 2,500 Hz or slower. This causes the entire planar fan 1085 and the despeckled illumination line 1082 to sweep along the slow scan direction 1094. DS system 1000 is also illustrated in FIG. 11, which shows a working area 1110 with a substantially uniform light beam (depicted by boundary 1120) projected onto a surface 1090.Also shown are the near work area NW and the far work area FW, and the projected illumination (laser) line is substantially uniform across the (slow) scan range (double arrow 1094) due to the angles selected for the components of the optical package 920.

[0061] Although linear diffuser 1072 has been described as being below cylindrical lens 1070 in the optical path, it will be appreciated that the linear diffuser may be located elsewhere in the optical path. For example, the linear diffuser may be located between mirror assembly 1020 and lens 1070 (position 1096 in FIG. 10), or at any other suitable location as would be apparent to one of ordinary skill in the art. Similarly, while described with polarizers and / or beam splitter(s), these components may be omitted or substituted in ways apparent to one of ordinary skill in the art as appropriate to the performance requirements and / or internal layout of the DS.

[0062] FIG. 12 shows an example of a scan pattern 1200 projected onto a surface 1210 (note that the planar view is for ease of illustration). The MEMS mirror assembly generates a beam of light in a fast scan direction (double arrow 1222) and sweeps the surface 1210 along a slow scan direction (double arrow 1224) to cover the entire working area. Although a series of scan lines 1232 are shown, a straight line is seen for each image frame obtained, from which a contour can be determined. It will be appreciated that in some embodiments, the mirror may sweep relatively quickly in the slow direction (such as when the MEMS mirror is swept in a resonant mode in that direction), at which time the laser may be pulsed or shuttered to avoid blurring the image of the beam obtained at the imager. For example, if the MEMS mirror is scanned at 20 kHz in the fast scan direction 1222 and 2 kHz in the slow scan direction 1224, then to properly compensate for the tilt in the center of the line 1232, the linear diffuser 1072 would need to be rotated 5.7° (atan(2 / 20)) to point in two directions. In this example, the laser 1010 would only need to be on for the center 80% of the sweep in only one direction, which is to move the sweep in a direction substantially perpendicular to the diffusing portion of the diffuser 1072. This example further suggests that the laser 1010 would need to be periodic at 10 kHz and have a duty cycle of less than 40% during the phase in which the mirror 1020 is swept. Spatial sampling is no different to other line scan systems. In the x-direction (direction of the line of illumination), the sampling resolution Sx is given by (i) the number of pixels Np projected on the part under test 1210 (PUT) divided by (ii) the length of the line of pixels Lp: Sx = Lp / Np. In our example, if the line of projected pixels is 100 mm long and the line consists of 1000 pixels, the spatial sampling in the x-direction (direction of the line of illumination) is 1 / 100 micron. In the y-direction (direction perpendicular to the line of illumination), the spatial sampling Sy is equal to the inter-sample distance Ds: Sy = Ds. In our example, if the line moves 1 mm after each exposure, the spatial sampling is 1 / 1 mm.The spatial resolution Rx, Ry can also be calculated similarly to a standard imaging system with a differentiator, and in addition to the convolution of the imaging system's blurred points, the line width in the y direction of the sweep line (averaged over the sweep) must also be convolved as in all laser line triangulation systems. However, more generally, it can be seen that the slow scan speed can be controlled to obtain a sweep that is precisely determined at the operating frame rate of the imager. For example, a MEMS mirror with linear control of the slow axis 1224 can be used so that the scan line steps to the position of interest and remains there during the integration / exposure time. To maximize speckle reduction, the minimum integration time should be at least half the full period length of the fast axis 1222 of the MEMS mirror. For a 20 kHz mirror, this is 25 microseconds. A system with a field lens 1070 can be used where the line 1232 is stationary (in the line direction) on the portion 1210, so that an even shorter integration time is required. With such short integration times, the speckle contrast increases by a factor of square root of two for each half of the minimum time. Once integration is complete, the imager can be shuttered and read out, allowing the MEMS mirror to advance the line during the readout time. Spatial sampling is similar to that described above. As the line sweeps across the surface, the image capture rate should be fast enough to capture the line with minimal blurring. The position of the line (along the y-axis) can be derived from the mirror motion based on the mirror control, and can be used to determine the relative position of the line (along the y-axis) within the working area. For example, if the mirror is commanded to move an angle of 5 degrees from its normal position, the law of reflection dictates that the beam will deflect by twice that angle, i.e., 2 x 5° = 10°. The mirror deflection angle can also be determined in an open-loop manner using look-up tables pre-calibrated for voltages in both electrostatic and galvanometer cases, or currents in electromagnetic MEMS cases. Knowledge of this angle can be used to adjust the profile height using standard triangulation techniques. Spatial sampling and resolution can be calculated as described above. Alternatively, the relative position of the line (along the y-axis) to the near and far boundaries of the work zone can be used to determine the relative position of the line.For example, when scanning an area smaller than the field of view, and the background of the measurement area is a flat plate, part of the beam will cross that area and can be used to accurately determine the line through which each illuminated surface must pass. Since all of these illuminated surfaces must pass through the intersection of the laser beam and the MEMS mirror, the complete positions of these illuminated surfaces are well determined. The spatial sampling and spatial resolution can be calculated as described above. Using the internal calibration of the DS, the contours of all imaged lines can be calculated accurately in the height direction (z-axis direction).

[0063] In a further embodiment, an optional second linear diffusing element can be used to spread the light beam into multiple beams along the y-axis. This allows multiple beams to sweep the image, generating multiple profiles. The dashed scan lines 1230 between the solid lines 1232 represent the beams in a single captured image frame. This allows multiple profiles to be captured per image frame, speeding up the overall scanning process. For example, a single scan could scan a single line along the part. Each camera frame would collect one profile per image. Then, if there are n equally spaced lines on the part, the distance or mirror angle on the part would only need to be moved 1 / n. Each camera frame would read n lines, resulting in n times more data. Thus, only 1 / n times the number of frames required for a single scan. If you scan a 100 mm area with a spatial resolution of 100 microns in the y direction, and assume a frame rate of 200 Hz, you will need 1000 images and 5 seconds to scan it, but if you use 10 beams, you will only need 100 images and 1 / 2 second to scan it.

[0064] In the image 1300 depicted in FIG. 13, there are two captured lines 1310, 1320. The upper line 1310 is a typical speckled light beam generated, for example, using a Powell lens. Note that this generally has uneven edges and rough texture that reduces the accuracy of the contour. Now, the lower line 1320 was generated using the DS configuration described above. It is substantially more uniform and sharp, which improves the accuracy of the contour and allows for brighter illumination, which in turn allows for faster scanning of the object. As an example, the upper line 1310 is 0.240 pixels rms wide with a variance of 1σ, and the lower line 1320 is 0.074 pixels rms wide with a variance of 1σ. This is the first measurement data from the first prototype according to the technology disclosed herein. We measured the speckle contrast at the noise floor (5%) of the initial demonstration board. To account for the fact that the diffuser scan length is only 25 mm and no field lens is used, a crude measurement shows that the speckle contrast is less than 10% when a 1 meter diffuser is used.

[0065] Now, referring to FIG. 14, a generalized flow diagram 1400 is shown illustrating the operation of a DS (e.g., DS 900) according to an example embodiment. In step 1410, the mirror control uses appropriate inputs (e.g., constant and / or modulated voltages) to drive the MEMS mirror at a first speed (fast) in a first direction and at a second speed (slow) in a second direction substantially perpendicular to the first direction. In step 1420, the projection beam can be (optionally) pulsed or shuttered to reduce blurring, allowing for cases where the slow scan speed is faster than the imaging speed of the element. In step 1430, the mirror control sends information about the slow speed to a vision processor to determine the position of the light beam along the y-axis. This information can also be derived from the captured images, by quantifying the relative position of the captured light beam in the image frame with respect to the boundaries of the working area, and / or by knowledge of how the mirror (and light beam) moves within each image frame through each capture timing. In step 1440, light rays projected onto objects in the scene can generate a profile that is captured by the imager. In step 1450, this profile can be used to calculate the height of the object in that slice, which can be based on internal calibration data as well as the slow scan speed, or other data that provides the y-axis position of the profile slice. In step 1460, the profile of the entire object can be stored and / or transmitted to downstream processing for further analysis or tasks (e.g., inspection).

[0066] It will be apparent that a DS (such as DS 900) can be sized to suit the desired vision system task, and those skilled in the art will also appreciate that associated components can be scaled up or down to obtain the functionality required to perform the task.

[0067] VII. Further Configurations and Uses

[0068] A wide variety of other uses and / or implementations of speckle-reduced illumination may also be provided in accordance with the present disclosure. FIG. 15 shows an example of a DS system 1500 that includes a speckle-reduced illumination generating system 1510. In the DS system 1500, a laser source 1511 emits a collimated beam 1512 to a beam generator 1520 (which may include some form of linear diffuser, as described above). Various optical components, filters, polarizers, beam splitters, etc. may also be provided as described above. The beam generator 1520 is operatively connected to a movable part (vibration driver) 1530 that can cause an oscillatory motion (e.g., periodic motion) in one or more planes (represented by double arrow 1532). The movable part may be a MEMS-based component, a voice coil, or any other suitable drive system (e.g., one that operates according to electromagnetic principles). The motion 1532 of the beam generator 1520 results in a beam 1540 at the intersection of the trajectory fan 1542 with the working surface 1541. The beam generator 1520 can generate the trajectory fan 1542 through a combination of divergence and displacement of the beam 1512. The system 1510 can be powered by suitable power supplies and control means as described above.

[0069] FIG 16 shows an example of a DS system 1600 including a beam generating system 1610. The beam generating system 1610 includes a laser source 1620, a moving part 1630, a beam generator 1640, and a beam deflector 1650 (optional and shown in dashed lines). The moving part 1630 can drive the beam generator 1640 in a manner similar to that described for the DS system 1500 in FIG 15. Alternatively, a stationary beam generator element (such as a linear diffuser) can be provided, with the beam deflector 1650 (such as a mirror that can be moved by a moving part) generating a trajectory fan 1660 from a collimated beam. The term "beam generator" in this example can be defined as either a diffusing optical element (or other optical element) directly combined with a moving part (as in the embodiment of FIG. 15) or a stationary diffusing element mounted with a moving part combined with a beam deflector (such as the MEMS mirror embodiment). That is, the beam deflector 1650 is depicted as being combined with the beam generator 1640 (with brackets 1652) because in some embodiments, these two components may be collectively referred to as the "beam generator." In particular, the beam generating system 1610 according to various configurations of the present disclosure may be used in applications other than machine vision applications where a despeckled and / or more uniform beam application is desired. As shown, the beam 1670 is the intersection of the trajectory fan 1660 with the separation surface 1680, which is a working distance DD from the beam generator 1640. In various embodiments, the working distance DD may be in centimeters, meters, tens of meters, or other distances. For example, the beam generating system may be used in architectural applications (such as surveying and targeting) to produce a more uniform and sharper beam.

[0070] More generally, the beam generating system according to various embodiments of the present disclosure may be used as an illumination system in machine vision (vision systems) and / or other applications. In the example DS system 1700 shown in FIG. 17, the beam generating system 1710 according to any embodiment or configuration of the present disclosure may be used to illuminate a scene / object 1720 in a 2D imaging application. The illumination provided has the advantage of being sharper and more distinct. It is also more uniform, and in nature, the illumination line 1730 (formed as the intersection of the planar fan 1732 and the scene / object 1720) can bend around obstacles and is generally resistant to distortion due to surface imperfections (notches). The beam generating system 1720 can be configured with a beam deflector (such as a MEMS mirror) that can oscillate along multiple axes (multiple degrees of freedom) to provide illumination as a region 1740 within the working area of ​​the imager SI. The imager SI may be part of a camera system 1750, which may be positioned via a beam splitter or the like, and may have an optical axis OAI that is coaxial / coplanar with the planar fan 1732. The light beam oscillation may be controlled fast enough to be seen by the imager SI as a single illuminated area (additively). Alternatively, the camera 1760 may define an optical axis OAI1 parallel to the plane of the planar fan 1732. The DS unit is generally good at 2D grayscale measurements, but the height displacement data from the illumination line 1730 enhances this advantage. The illumination line 1730 reduces speckle and improves uniformity, resulting in a more accurate grayscale representation of the scene / object.

[0071] In one implementation, an illumination device for reducing speckle in light reflected from an illuminated object can be configured according to the following aspects.

[0072] In general aspect 1, an irradiation device includes: a light source configured to emit coherent light; a linear diffuser positioned in an optical path between the target and the light source and configured to diffuse the coherent light into a diffuse light beam extending along a plane across at least a portion of the target, the diffuse light beam having an associated exposure time for illuminating the target; a beam deflector positioned in the optical path between the light source and the linear diffuser; a control means coupled to the beam deflector; Including, The diffused light forms a planar fan light that does not generally spread along a direction perpendicular to the one surface; the control means is configured to operate the beam deflector such that the coherent light is projected onto the beam deflector to sweep through a plurality of positions on the linear diffuser during the exposure time during which the target is illuminated by the diffused light; and The plurality of locations span a distance across the linear diffuser that provides a speckle pattern at an image sensor for light reflected from an intersection of the planar fan light with the target that is sufficiently uncorrelated to add non-coherently when imaged by the image sensor during the exposure time during which the target is illuminated by the diffuse light. It is characterized by:

[0073] As a second aspect according to the first aspect, the laser source comprises a laser.

[0074] As an embodiment according to the first or second aspect, the beam deflector includes a micro-electro-mechanical system (MEMS) mirror.

[0075] As an embodiment 4 according to the embodiment 1 or 2, the beam deflector includes an acousto-optical modulation (AOM) device.

[0076] As a fifth aspect according to any one of the first to fourth aspects, a cylindrical lens located in the optical path between the linear diffuser and the beam deflector; Including, The cylindrical lens acts as a field lens to increase efficiency by concentrating all of the coherent light directed towards the linear diffuser.

[0077] As a sixth aspect according to any one of the first to fourth aspects, Cylinder Lens Including, the linear diffuser is located between the beam deflector and the cylinder lens; and The cylinder lens is configured to act as a field lens to increase efficiency by concentrating all of the diffuse light directed toward the target.

[0078] As a seventh embodiment in accordance with any one of the first to sixth embodiments, the linear diffuser includes a textured diffuser with a flat-top intensity profile along the one surface.

[0079] As an eighth aspect according to any one of the first to sixth aspects, the linear diffuser includes a chirped diffraction grating having a free spectral range (FSR), such that the spacing of the diffraction lines in the planar fan light is varied with the sweep angle of the coherent light projected onto the linear diffuser.

[0080] As an embodiment 9 according to any one of the embodiments 1 to 6, the linear diffuser includes a hologram or a cylinder array.

[0081] As a tenth aspect according to any one of the above aspects, the linear diffuser is stationary relative to a base of the beam deflector; The control means is configured to operate the beam deflector so that the coherent light periodically sweeps left-right-left relative to the linear diffuser, such that the coherent light is guided through either the left-right half or the right-left half of the left-right-left sweep during the exposure time during which the target is illuminated by the diffused light.

[0082] In one implementation, the laser displacement measurement system can be configured in the following manner.

[0083] In general aspect 11, a laser displacement measurement system includes: a vision system processor; a camera component coupled to said vision system processor; a laser beam component coupled to the vision system processor and configured to project coherent light; a beam deflector disposed to receive the coherent light; a control means coupled to said beam deflector; a linear diffuser located in the optical path between the irradiation object and the beam deflector; Including, the control means is configured to operate the beam deflector to direct the coherent light projected onto the beam deflector to sweep through a plurality of positions on the linear diffuser; the linear diffuser is configured to diffuse the coherent light received from the beam deflector at the plurality of locations to obtain diffuse light, the diffuse light extending in a plane across at least a portion of the target and having an associated exposure time for the target to be illuminated by the diffuse light, the diffuse light forming a planar fan light that does not substantially extend in a direction perpendicular to the plane; The multiple positions are present over a distance across the linear diffuser, and light reflected from the intersection of the planar fan light with the target is provided with a sufficiently uncorrelated speckle pattern at the image sensor so that it adds non-coherently when imaged by the image sensor within the exposure time during which the target is illuminated by the diffuse light.

[0084] As an embodiment 12 according to the embodiment 11, the linear diffuser is stationary relative to a base of the beam deflector; The control means is configured to operate the beam deflector so that the coherent light periodically sweeps left-right-left relative to the linear diffuser, and the control means is configured to operate the beam deflector so that the coherent light is directed through either the left-right half or the right-left half of the left-right-left sweep within the exposure time during which the target is illuminated by the diffused light.

[0085] As an embodiment 13 according to embodiment 11 or 12, the linear diffuser comprises a textured diffuser with a flat-top intensity profile along the one face.

[0086] As an embodiment 14 according to embodiment 11 or 12, the linear diffuser comprises an array of cylinders.

[0087] As an embodiment 15 according to embodiment 11 or 12, the linear diffuser comprises a hologram.

[0088] As an embodiment 16 according to the embodiment 15, the hologram is configured to project the planar fan light onto the illumination target in a non-continuous pattern.

[0089] As an embodiment 17 according to the embodiment 16, the non-continuous pattern includes at least one of a group of points and a group of line segments separated by non-irradiated intervals.

[0090] As an embodiment 18 according to embodiment 11 or 12, the linear diffuser includes a chirped diffraction grating having a free spectral range (FSR) such that the spacing of diffracted beams in the planar fan of light can be varied with the sweep angle of the coherent light projected onto the linear diffuser.

[0091] As an embodiment 19 according to any one of the embodiments 11 to 18, the beam deflector includes a micro-electro-mechanical system (MEMS) mirror.

[0092] As an embodiment 20 according to any one of the embodiments 11 to 18, the beam deflector includes an acousto-optical modulator (AOM) device.

[0093] As an embodiment 21 according to any one of embodiments 11 to 20, a cylindrical lens positioned in the optical path between the linear diffuser and the beam deflector; Including, The cylindrical lens is configured to act as a field lens to increase efficiency by concentrating all of the coherent light directed towards the linear diffuser.

[0094] As an embodiment 22 according to any one of embodiments 11 to 20, Cylinder Lens Including, the linear diffuser is located between the beam deflector and the cylinder lens; and The cylinder lens is configured to act as a field lens to increase efficiency by concentrating all of the diffuse light directed toward the target.

[0095] As an embodiment 23 according to any one of the embodiments 11 to 22, the laser beam component includes a laser.

[0096] As an embodiment 24 according to any one of embodiments 11 to 23, The camera parts include capturing light reflected from an intersection of the planar fan light with the illumination target; Generate image data from captured light It is configured as follows.

[0097] As an embodiment 25 according to embodiment 24, the vision system processor: receiving the image data from the camera assembly; Processing the image data to perform at least one of a measurement and an inspection on the region of the illuminated object. It is configured as follows.

[0098] As an embodiment 26 according to any of embodiments 11 to 25, the camera component includes an image sensor having a first optical axial surface and a lens component having a second optical axial surface non-parallel to the first optical axial surface, each oriented relative to the planar fan light according to the Scheimpflug principle.

[0099] In one implementation, a system for producing a speckle-reduced light beam on a work surface can be configured according to the following aspects.

[0100] In general aspect 27, a system comprises: a laser source in the form of a collimated beam; a light beam generator that receives at least a portion of the collimated beam and projects the light passing therethrough as a light beam onto a work surface; a movable part for moving the parallel beam with a vibratory motion substantially in one or more planes; Includes.

[0101] As an embodiment 28 according to embodiment 27, the laser source comprises a stationary laser source; moreover a movable beam deflector operatively connected to the movable portion; Includes.

[0102] As an embodiment 29 according to embodiment 28, the movable part and the beam deflector include any one of a MEMS mirror, a voice coil operated mirror, a piezoelectric operated mirror, and a solid-state mirror unit.

[0103] As an aspect 30 according to aspect 29, the MES mirror is configured to vibrate along two substantially orthogonal degrees of freedom such that the light beam is generated along a first direction and the light beam moves along a second direction on the work surface.

[0104] As an embodiment 31 according to the embodiment 28, further comprising: A beam splitter; a polarizer component that reduces back reflections from the beam splitter and directs the beam to the beam deflector; Includes.

[0105] As an embodiment 32 according to any one of the embodiments 27 to 31, the light generator includes a linear diffuser.

[0106] As an embodiment 33 according to any one of the embodiments 27 to 32, a field lens that is either: (a) located between the oscillating laser source and the light beam generator; and (b) integral with the light beam generator and located between the oscillating laser source and the light beam generator. Includes.

[0107] As an embodiment 34 according to any one of the embodiments 27 to 33, light from at least a portion of the work surface is captured by a sensor (image capture element), and the sensor generates image data from the captured light.

[0108] As an embodiment 35 according to embodiment 34, the image data is used by a processor to at least one of measure and inspect an area of ​​a work surface.

[0109] As an embodiment 36 according to any of the embodiments 27 to 35, the work surface defines at least a portion of an object to be measured or inspected.

[0110] As an embodiment 37 according to any of the embodiments 27 to 36, the light beam generator is used to construct at least one of a laser displacement sensor and an illumination source.

[0111] As an embodiment 38 according to embodiment 37, the laser displacement sensor is operatively connected to a vision system processor.

[0112] As an embodiment 39 according to any one of embodiments 27 to 31 and 33 to 38, the light beam generator includes an optical component having one or more of a linear diffuser, a hologram, and a cylinder array.

[0113] As an embodiment 40 according to embodiment 39, the light beam generator is used to either (a) project the light beam in a non-continuous pattern, and (b) project the light beam in a pattern defined by at least one of a point cloud and a line segment group divided by non-irradiation intervals.

[0114] In one implementation, a method for generating a speckle-reduced light beam can be performed according to the following aspects.

[0115] In general aspect 41, a method comprises: irradiating a laser source in the form of a collimated beam; transmitting the collimated beam through a light beam generator and onto the work surface; vibrating the parallel beam such that the parallel beam undergoes an oscillatory motion substantially in one plane; Includes.

[0116] As an embodiment 42 according to embodiment 41, the oscillation includes projecting a stationary laser beam source onto a movable beam deflector.

[0117] As an aspect 43 according to aspect 41 or 42, the transmitting includes passing the collimated beam through a field lens positioned coaxially with the light beam generator.

[0118] As an embodiment 44 according to any one of the embodiments 41 to 43, capturing at least a portion of the light beam projected onto the work surface with a sensor; generating image data from the captured light by said sensor; Includes.

[0119] As an embodiment 45 according to the embodiment 44, Processing the image data to perform at least one of a measurement and an inspection on an area of ​​the work surface. Includes.

[0120] As an embodiment 46 according to any of the embodiments 41 to 45, the work surface defines at least a portion of an object to be measured or inspected.

[0121] As an aspect 47 according to any one of aspects 41 to 43, the vibrating step includes: oscillating the beam deflector about a first axis at a first velocity and about a second axis substantially orthogonal to the first axis at a second velocity. Includes.

[0122] In one implementation, a system for reducing speckle and / or glint in a light beam projected onto a surface can be configured according to the following aspects.

[0123] In a general aspect 48, a system includes: A parallel light source, an optical component that generates a fan-shaped light within one or more predetermined angles on either side of a central optical axis; a light beam generator positioned between the optical component and a surface through which the fan light passes; Includes.

[0124] As an embodiment 49 according to embodiment 48, the optical component includes one or more of a MEMS mirror, a solid phase deflector, and a Powell lens.

[0125] In one implementation, a system for scanning a surface and quantifying a 3D profile can be configured according to the following aspects.

[0126] In a general embodiment 50, a system includes: a vision system camera that images the surface along an optical axis; A parallel light source, a MEMS mirror that receives the collimated light source and projects it onto the surface at an angle non-parallel to the optical axis; a mirror control means for vibrating the MEMS mirror along two or more orthogonal degrees of freedom to (a) generate a fan of light along a first direction within one or more predetermined angles on either side of a central optical axis, and (b) move the fan of light along a second direction to cause the fan of light to scan a surface; a light beam generator positioned between the MEMS mirror and the surface, through which the fan light passes; Includes.

[0127] As an embodiment 51 according to embodiment 50, the present invention further includes at least one of (a) a polarizing beam splitter / polarizer installed along the optical path of the parallel light source, and (b) a cylindrical lens in the optical path.

[0128] As an embodiment 52 according to embodiment 50 or 51, the light beam generator includes a linear diffuser.

[0129] As an embodiment 53 according to any of embodiments 50 to 52, the mirror control means vibrates the MEMS mirror at a first speed along the first direction and at a second speed slower than the first speed along the second direction.

[0130] As an embodiment 54 according to any of embodiments 50 to 52, the vision system camera includes an imaging element having a first optical axial surface and a lens having a second optical axial surface that is non-parallel to the first optical axial surface, each of which is oriented in accordance with the Scheimpflug principle with respect to a plane defined by the fan.

[0131] In one implementation, a system for producing a speckle-reduced light beam on a work surface can be configured according to the following aspects.

[0132] In general aspect 55, a system comprises: an oscillating laser source in the form of a collimated beam moving with a sweeping periodic motion in a plane; a light beam generator that receives the moving collimated beam and projects it as a straight line onto the work surface through light; Includes.

[0133] As an embodiment 56 according to embodiment 55, the oscillating laser source includes a stationary laser source and a periodically movable beam deflector.

[0134] As an embodiment 57 according to embodiment 56, the beam deflector includes a MEMS mirror.

[0135] As an embodiment 58 according to embodiment 56, the beam deflector is driven by a galvanometer.

[0136] As an embodiment 59 according to embodiment 56, the beam deflector is a solid unit.

[0137] As an embodiment 60 according to any one of the embodiments 55 to 59, the light generator is a linear diffuser.

[0138] As an embodiment 61 according to any one of the embodiments 55 to 60, A field lens positioned between the oscillating laser source and the beam generator. Includes.

[0139] As an embodiment 62 according to embodiment 61, the field lens is integral with the light beam generator.

[0140] As an embodiment 63 according to any one of the embodiments 55 to 62, the light beam generator is mounted within a laser displacement sensor.

[0141] As an embodiment 64 according to embodiment 63, the laser displacement sensor is operatively connected to a vision system processor.

[0142] As an embodiment 65 according to any one of embodiments 55 to 59 and 61 to 64, the light beam generator includes an optical component having one or more of a linear diffuser, a hologram, and a cylinder array.

[0143] As an embodiment 66 according to embodiment 65, the light beam generator projects the light beam in a non-continuous pattern.

[0144] As an embodiment 67 according to embodiment 66, the non-contiguous pattern defines at least one of a group of points and a group of line segments separated by non-irradiated intervals.

[0145] In one implementation, a method for generating a speckle-reduced light beam can be performed according to the following aspects.

[0146] In general aspect 68, a method includes: oscillating a laser source in the form of a collimated beam in a periodic sweeping motion in a plane; transmitting the collimated beam through a beam generator and onto a work surface as a straight line; Includes.

[0147] As an embodiment 69 according to embodiment 68, the oscillation includes projecting a stationary laser beam source onto a periodically moving beam deflector.

[0148] As an embodiment 70 according to embodiment 68 or 69, the transmitting step includes passing the collimated beam through a field lens positioned coaxially with the light beam generator.

[0149] As an example 71 according to any one of examples 68 to 70, the transmitting step includes passing the collimated beam through one or more of a linear diffuser, a hologram, and a cylindrical array.

[0150] As an embodiment 72 according to the embodiments 68 to 71, receiving reflected light (including said light beam) from said work surface with a vision system sensor; processing image data generated by the vision system sensor; Includes.

[0151] In one implementation, a system for reducing speckle and / or glint in a light beam projected onto a surface can be configured according to the following aspects.

[0152] In a general aspect 73, a system comprises: A parallel light source, an optical component that generates a fan-shaped light within one or more predetermined angles on either side of a central optical axis; a light beam generator positioned between the optical component and a surface through which the fan light passes; Includes.

[0153] As an embodiment 74 according to embodiment 73, the optical component includes one or more of a MEMS mirror, a solid phase deflector, and a Powell lens.

[0154] As an embodiment 75 according to embodiment 73 or 74, the parallel light source is a laser.

[0155] VIII. Conclusion

[0156] It will be apparent that the speckle-reducing beam generating system described above can provide an improved illumination beam that can be used for a variety of purposes, including 3D displacement sensors and associated vision system operations. By using a beam deflector or other mechanism to periodically oscillate the source beam and a linear diffuser to efficiently generate the beam, the need for a Powell lens or other beam generating optics can be eliminated. This has the benefit of reducing the cost of the system and significantly improving the quality of the projected and imaged beam. In addition, the use of a 2D scanning laser in some embodiments eliminates the need for separate moving parts (motion stage, conveyor, etc.) to scan the object. By using a scanning laser in combination with a diffuser, the system can efficiently blur out any extraneous object defects (such as dust on the inner and outer surfaces of the optical components), which can improve the manufacturing quality of the DS.

[0157] The above description provides a detailed description of exemplary embodiments of the present invention. Various modifications and additions may be made without departing from the spirit and scope of the present invention. Features of each of the various embodiments described above may be appropriately combined with other features of other described embodiments to provide various combinations of features associated with new embodiments. Although numerous embodiments of the apparatus and method according to the present invention have been described above, it should be noted that the description herein is merely illustrative of the application of the principles of the present invention. For example, the various terms (and grammatical conjugations) used herein to indicate directions and orientations, such as "vertical", "horizontal", "up", "down", "bottom", "top", "side", "front", "rear", "left", "right", "forward", "rearward", etc., are used as relative conventions and are not used as absolute orientations (such as the direction of gravity) relative to a fixed coordinate system. It should also be noted that when the terms "substantially" or "approximately" are used with respect to a given measurement, value, or characteristic, it refers to an amount within the normal working range that produces a desired result, but also includes variations due to unavoidable deviations and errors within the system tolerances (e.g., 1-2%). In addition, the terms "process" and / or "processor" in this specification should be interpreted broadly to include various electronic hardware and / or software based on functions and components. Also, the illustrated process or processor may be combined with other processes and / or processors, or may be divided into various sub-processes or sub-processors. Such sub-processes and / or sub-processors may also be variously combined according to the embodiments of the present disclosure. Similarly, it should be apparent that any function, process, and / or processor in this specification may be implemented using electronic hardware, software consisting of a non-transitory computer-readable medium having program instructions, or a combination of hardware and software.Additionally, the terms "slow" and "fast" used herein with respect to scanning speed are relative terms and do not represent any absolute range of speeds unless otherwise specified. Therefore, the present disclosure should be construed as merely illustrative and not as limiting the scope of the present invention.

Claims

1. 1. An illumination device for reducing speckle in light reflected from an illumination object, comprising: a light source configured to emit coherent light; a linear diffuser positioned in an optical path between the target and the light source and configured to diffuse the coherent light into a diffuse light beam extending along a plane across at least a portion of the target, the diffuse light beam having an associated exposure time for illuminating the target; a beam deflector positioned in the optical path between the light source and the linear diffuser; a control means coupled to the beam deflector; Including, The diffused light forms a planar fan light that does not generally spread along a direction perpendicular to the one surface; the control means is configured to operate the beam deflector such that the coherent light is projected onto the beam deflector to sweep through a plurality of positions on the linear diffuser during the exposure time during which the target is illuminated by the diffuse light; and The plurality of locations span a distance across the linear diffuser that provides a speckle pattern at an image sensor for light reflected from an intersection of the planar fan light with the target that is sufficiently uncorrelated to add non-coherently when imaged by the image sensor during the exposure time during which the target is illuminated by the diffuse light. An irradiation device comprising:

2. The irradiation device of claim 1 , wherein the laser source comprises a laser.

3. 3. The illumination device of claim 1 or 2, wherein the beam deflector comprises a micro-electro-mechanical system (MEMS) mirror.

4. 3. The illumination device of claim 1 or 2, wherein the beam deflector comprises an acousto-optical modulator (AOM) device.

5. moreover a cylindrical lens located in the optical path between the linear diffuser and the beam deflector; Including, The cylindrical lens acts as a field lens to increase efficiency by concentrating all of the coherent light directed towards the linear diffuser.

2. The irradiation device according to claim 1 .

6. moreover Cylinder Lens Including, the linear diffuser is located between the beam deflector and the cylinder lens; and The cylindrical lens is configured to act as a field lens to increase efficiency by concentrating all of the diffuse light directed toward the illumination target.

2. The irradiation device according to claim 1 .

7. 10. The illumination device of claim 1, wherein the linear diffuser comprises a modified diffuser with a flat-top intensity profile along the one surface.

8. 2. The illumination device of claim 1, wherein the linear diffuser includes a chirped diffraction grating with a free spectral range (FSR) such that the spacing of diffraction lines in the planar fan of light varies with the sweep angle of the coherent light projected onto the linear diffuser.

9. The illumination device of claim 1 , wherein the linear diffuser comprises a hologram or a cylinder array.

10. the linear diffuser is stationary relative to a base of the beam deflector; The control means is configured to operate the beam deflector so that the coherent light periodically sweeps left → right → left relative to the linear diffuser, so that the coherent light is guided through either the left → right half or the right → left half of the left → right → left sweep during the exposure time during which the irradiation target is illuminated by the diffused light.

2. The irradiation device according to claim 1 .

11. A laser displacement measurement system, comprising: a vision system processor; a camera component coupled to said vision system processor; a laser beam component coupled to the vision system processor and configured to project coherent light; a beam deflector positioned to receive the coherent light; a control means coupled to said beam deflector; a linear diffuser located in the optical path between the irradiation object and the beam deflector; Including, the control means is configured to operate the beam deflector to direct the coherent light projected onto the beam deflector to sweep through a plurality of positions on the linear diffuser; the linear diffuser is configured to diffuse the coherent light received from the beam deflector at the plurality of locations to obtain diffuse light, the diffuse light extending in a plane across at least a portion of the target and having an associated exposure time for the target to be illuminated by the diffuse light, the diffuse light forming a planar fan light that does not substantially extend in a direction perpendicular to the plane; The plurality of positions are present across a distance across the linear diffuser, and light reflected from an intersection of the planar fan light with the target is provided with a sufficiently uncorrelated speckle pattern at an image sensor such that the light is non-coherently summed when imaged by the image sensor during the exposure time during which the target is illuminated by the diffuse light. A laser displacement measurement system comprising:

12. the linear diffuser is stationary relative to a base of the beam deflector; The control means is configured to operate the beam deflector to cause the coherent light to periodically sweep left-right-left relative to the linear diffuser, and the control means is configured to operate the beam deflector to direct the coherent light through either the left-right half or the right-left half of the left-right-left sweep during the exposure time during which the target is illuminated by the diffused light.

12. The laser displacement measurement system according to claim 11 .

13. 13. The laser displacement measurement system of claim 11 or 12, wherein the linear diffuser comprises a machined diffuser with a flat-top intensity profile along the one surface.

14. 13. The laser displacement measurement system of claim 11 or 12, wherein the linear diffuser comprises an array of cylinders.

15. 13. The laser displacement measurement system of claim 11 or 12, wherein the linear diffuser comprises a hologram.

16. 16. The laser displacement measurement system of claim 15, wherein the hologram is configured to project the planar fan of light onto the illumination target in a non-continuous pattern.

17. 17. The laser displacement measurement system of claim 16, wherein the non-contiguous pattern comprises at least one of a cloud of points and a cloud of line segments separated by non-illuminated intervals.

18. 13. The laser displacement measurement system of claim 11 or 12, wherein the linear diffuser includes a chirped grating having a free spectral range (FSR) such that the spacing of diffracted beams in the planar fan of light varies with the sweep angle of the coherent light projected onto the linear diffuser.

19. The laser displacement measurement system of claim 11 , wherein the beam deflector comprises a microelectromechanical system (MEMS) mirror.

20. The laser displacement measurement system of claim 11 , wherein the beam deflector comprises an acousto-optical modulator (AOM) device.

21. moreover a cylindrical lens positioned in the optical path between the linear diffuser and the beam deflector; Including, The cylindrical lens is configured to act as a field lens to increase efficiency by concentrating all of the coherent light directed toward the linear diffuser.

12. The laser displacement measurement system according to claim 11 .

22. moreover Cylinder Lens Including, the linear diffuser is located between the beam deflector and the cylinder lens; and The cylindrical lens is configured to act as a field lens to increase efficiency by concentrating all of the diffuse light directed toward the illumination target.

12. The laser displacement measurement system according to claim 11 .

23. The laser displacement measurement system of claim 11 , wherein the laser beam component comprises a laser.

24. The camera parts include capturing light reflected from an intersection of the planar fan light with the illumination target; Generate image data from captured light 12. The laser displacement measurement system of claim 11 configured to:

25. the vision system processor: receiving the image data from the camera assembly; Processing the image data to perform at least one of a measurement and an inspection on the region of the illuminated object.

25. The laser displacement measurement system of claim 24 configured to:

26. 12. The laser displacement measurement system of claim 11, wherein the camera assembly includes an image sensor having a first optical axis plane and a lens assembly having a second optical axis plane non-parallel to the first optical axis plane, each oriented according to the Scheimpflug principle with respect to the planar fan light.

Images