Optical high-resolution displacement measurement

Abstract

The miniature displacement sensor comprises a light intensity pattern object, a microlens array, and an imaging device including a light intensity measurement surface. The microlens array is disposed between the light intensity pattern object and the imaging device such that each microlens focuses a corresponding sub-image constituting a portion of the light intensity pattern onto the light intensity measurement surface to create an image of the object on the light intensity measurement surface including an array of focused sub-images. The displacement sensor can provide a high resolution measurement of the displacement of the light intensity pattern object from a reference position by registering subsequent images captured after a change in the relative position between the light intensity pattern object and the imaging device to a reference image based on the pattern portion in the focused sub-image.

Description

[Background technology]

[0001] Displacement sensors can accommodate a variety of applications in which a measurement of the size, length, or quantity of something can be calculated, at least in part, based on the displacement measurement. Displacement sensors have practical applications in which they are used to measure linear displacement and rotational angle, rate of linear displacement and rotation, force including multi-axial forces, torque, moment, strain, load, acceleration in one or more directions, inertia, and pressure, among many others. [Prior art documents] [Non-patent literature]

[0002] [Non-Patent Document 1] Gao et al., "Displacement sensing and estimation theory and applications," Applied Physics A, 80(6), pp. 1265-1278. Summary of the Invention [Means for solving the problem]

[0003] Features and advantages of the devices and methods disclosed and taught herein will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the disclosed embodiments. [Brief explanation of the drawings]

[0004] [Figure 1] FIG. 1 is a side view of a sensor according to embodiments and teachings herein. [Figure 2] FIG. 2 is a pictorial diagram illustrating the arrangement of components of the sensor illustrated in FIG. 1. [Figure 3]FIG. 3 is an exemplary pictorial diagram depicting the arrangement of the components of the sensor illustrated in FIG. 2, showing that the microlens array is coupled to the imaging device after displacement of a light intensity pattern object relative to the imaging device. [Figure 4A] FIG. 1 is a ray diagram for a multi-microlens element, showing one or more optical elements operating along one of multiple optical axes within a microlens array. [Figure 4B] FIG. 10 is a ray diagram of one or more optical elements operating along one of multiple optical axes in a microlens array, the ray diagram being for a single microlens element according to an alternative embodiment. [Figure 5] FIG. 1 illustrates a light intensity measuring surface including light sensing elements configured to sense a light intensity pattern including a matrix of sub-images corresponding to image elements according to embodiments and teachings herein. [Figure 6A] 1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 6B] 1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 6C] 1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 6D] 1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 6E] 1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 6F] 1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 6G] 1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 6H] 1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 6I] 1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 6J]1 is an illustration depicting characteristics of a light intensity pattern in accordance with an illustrative embodiment; [Figure 7A] FIG. 10 is a pictorial diagram depicting an alternative arrangement of sensor components according to embodiments and teachings herein. [Figure 7B] FIG. 10 is a pictorial diagram depicting an alternative arrangement of sensor components according to embodiments and teachings herein. [Figure 8] FIG. 1 illustrates an application of a sensor according to embodiments and teachings herein. [Figure 9] FIG. 1 illustrates an application of a sensor according to embodiments and teachings herein. [Figure 10A] FIG. 1 is a perspective view of a sensor illustrating relative movement of sensor components in multiple degrees of freedom. [Figure 10B] FIG. 1 is a perspective view of a sensor illustrating relative movement of sensor components in multiple degrees of freedom. [Figure 10C] FIG. 1 is a perspective view of a sensor illustrating relative movement of sensor components in multiple degrees of freedom. [Figure 10D] FIG. 1 is a perspective view of a sensor illustrating relative movement of sensor components in multiple degrees of freedom. [Figure 11] FIG. 1 illustrates an example sensor configuration according to embodiments and teachings herein. [Figure 12] 1 is a flowchart illustrating a method for displacement measurement according to embodiments and teachings herein. [Figure 13] 1 is a flowchart illustrating a method for displacement measurement according to embodiments and teachings herein. DETAILED DESCRIPTION OF THE INVENTION

[0005] In one embodiment, an apparatus for measuring displacement may include a light intensity pattern object, an imaging device including a light intensity measuring surface, and a microlens array. The microlens array may be disposed between the light intensity pattern object and the light intensity measuring surface such that each microlens of the microlens array views a corresponding respective portion of the light intensity pattern object as a sub-image. Each microlens of the microlens array may focus each respective sub-image onto the light intensity measuring surface such that the microlens array forms an array of focused sub-images that form a sensed image of the light intensity pattern object on the light intensity measuring surface. The imaging device may be configured to capture the sensed image and register the sensed image to a reference image of the light intensity pattern object based on the light intensity pattern portions in the focused sub-images, thereby providing a measurement of the displacement of the light intensity pattern object relative to the imaging device.

[0006] In some embodiments, the imaging device may be configured to register the sensed image to the reference image by an image registration algorithm that maps portions of the light intensity pattern in the at least partially focused sub-image to corresponding portions of the light intensity pattern in the reference image.

[0007] In some embodiments, the microlens array may be rigidly affixed to either the light intensity patterning object or the imaging device.

[0008] In some embodiments, the light intensity pattern object may include a patterned substrate that defines a light intensity pattern, which may be unique for each displacement of the light intensity pattern object relative to the imaging device such that the image registration processor generates a single displacement solution for each possible displacement.

[0009] In some embodiments, each respective sub-image may correspond to the central axis of each corresponding microlens in the microlens array such that each sub-image is spatially distinct from all other sub-images.

[0010] In some embodiments, the light intensity pattern object may comprise a light source that generates diffuse light and a mask that includes transparent and opaque regions. In some embodiments, the light intensity pattern object may comprise a UV light source and a fluorescent material, and the UV light source may excite the fluorescent material. In some embodiments, the light intensity pattern object may comprise a phosphorescent material. In some embodiments, the light intensity pattern object may comprise a chemiluminescent material. In some embodiments, the light intensity pattern object may comprise at least a light emitting diode (LED) array or a quantum dot array. In some embodiments, the light intensity pattern object may comprise an array of light valves.

[0011] In some embodiments, the light intensity pattern object and imaging device may be configured to measure at least one of strain, force, torque, acceleration in one or more directions, rotational velocity, rotational angle, multi-axial force or moment, or any combination thereof. In some embodiments, any of the above measurements may be based on registration.

[0012] In one embodiment, a method for measuring displacement includes forming an array of sub-images of a light intensity pattern object. The method may further include focusing the array of spatially distinct sub-images onto a light intensity measuring surface of an imaging device as an array of focused spatially distinct sub-images that form a composite sensed image of the light intensity pattern object. The method may further include registering the composite sensed image to a reference image based on the focused spatially distinct sub-images.

[0013] In some embodiments, registering may be performed by mapping pattern portions in a sub-image of the sensed image to corresponding pattern portions in a corresponding sub-image of the reference image.

[0014] In one embodiment, an apparatus for measuring displacement includes a light intensity measurement surface, a light intensity pattern object, and an imaging device including an array of microlenses. The light intensity pattern object can be configured to propagate a light intensity pattern characterized by variations in light intensity along a cross section defined by one or more axes of a light pattern object coordinate system toward the light intensity measurement surface. The array of microlenses can be disposed between the light intensity pattern object and the light intensity detection surface such that each microlens in the array forms a sub-image of a corresponding portion of the light intensity pattern. The microlenses can focus the sub-images as an array of focused sub-images that form a sensed image of the light intensity pattern on the light intensity measurement surface. Displacement of the light intensity pattern object can be determined by registering the sensed image to a reference image.

[0015] In some embodiments, the array of microlenses can be rigidly affixed to either the light-patterning object or the imaging device.

[0016] In some embodiments, each microlens includes at least two lenses aligned on the same optical axis.

[0017] In one embodiment, a method for measuring relative displacement includes focusing a light intensity pattern onto a light intensity measuring surface of an imaging device to form an image of an object using a plurality of lens elements, each lens element including one or more lenses and each lens element having a respective optical axis. The method may further include measuring the displacement of the object relative to the imaging device by registering the sensed image of the object to a reference image of the object based on the light intensity pattern.

[0018] In some embodiments, registering may include comparing multiple portions of the light intensity pattern in the sensed image with multiple corresponding portions of the light intensity pattern in a reference image of the object.

[0019] In some embodiments, the light intensity pattern may be generated using a light source that generates diffuse light and a mask that includes transparent and opaque regions. In some embodiments, the light intensity pattern may be generated using a UV light source and a fluorescent material, where the UV light source excites the fluorescent material. In some embodiments, the light intensity pattern may be generated using a phosphorescent material. In some embodiments, the light intensity pattern may be generated using a chemiluminescent material. In some embodiments, the light intensity pattern may be generated using at least a light emitting diode (LED) array or a quantum dot array. In some embodiments, the light intensity pattern may be generated using an array of light valves.

[0020] The term "displacement" refers to a change in the position or orientation of an object in space. An object can be any type of tangible, tangible object, device, structure, or component. The term "degrees of freedom" refers to the number of independent motions permitted to an object. A rigid free object has six degrees of freedom: three rotations and three translations about each perpendicular axis.

[0021] "Rigid displacement" refers to the displacement of an object in which each point on the object experiences the same displacement. Deformable displacement refers to the displacement of an object in which each point on the object can experience a different displacement.

[0022] Relative rigid body displacement can refer to the displacement of a first object or structure relative to a second object or structure. The term "relative deformable displacement" can refer to the displacement of a first portion of a structure relative to the initial position or orientation of the first structure, or relative to a second portion of the structure that has undergone a different displacement. In that context, relative deformable displacement can be an indicator of reversible and / or irreversible strain and / or structural damage.

[0023] The "optical axis" of an optical system is a line centered about any degree of rotational symmetry within the optical system. Conventional displacement measurement systems provide displacement measurements that can vary substantially in their resolution depending on the degrees of freedom of movement allowed for the sensor component and / or the structure to which the sensor component is affixed. For example, a one-degree-of-freedom displacement sensor may provide high-resolution displacement measurements compared to the resolution that would be provided if there were no constraints on the degrees of freedom of movement. Conventional multi-degree-of-freedom displacement sensors may provide high-resolution displacement measurements in only one or two degrees of freedom allowed compared to the resolution that would be provided in the other degrees of freedom allowed.

[0024] Prior art solutions include adding redundant sensors to achieve high-resolution displacement measurements where displacement may result from motion in multiple degrees of freedom, however, this solution has the disadvantage that the redundant sensors may significantly increase the size, complexity, and / or cost of the displacement measurement device.

[0025] The sensors disclosed herein overcome the shortcomings of prior art sensors through component arrangements and configurations that provide high-resolution displacement measurements without increasing size, cost, or complexity, and without requiring redundant sensors to measure the displacement of objects that can move in more than two degrees of freedom.

[0026] 1 illustrates an exemplary displacement sensor 100 embodying the teachings herein. As shown in FIG. 1, the sensor 100 comprises a light intensity pattern object 120, a microlens array 227, and an imaging device 110 including a light intensity measuring surface 111.

[0027] The light intensity pattern object 120 serves as a "proxy" target object, i.e., an object whose change in position and / or orientation is determined by the imaging device 110 to determine the displacement of another object or structure to which the light intensity pattern object 120 is rigidly affixed. The light intensity pattern object 120 is therefore an integral component of the sensor 100. The light intensity pattern object 120 comprises one or more light sources 122 and a patterned substrate 121 configured as a multidimensional array 1855 of light intensity pattern portions (examples are illustrated in Figures 2 and 3) that define the light intensity pattern of the light intensity pattern object 120.

[0028] The light intensity pattern object 120 emits light 123 that generally propagates along a longitudinal axis (z-axis in 104) that is generally perpendicular to the patterned substrate 121 in the relative spatial orientation of the patterned substrate 121 and the light measurement surface 111. Each respective light intensity pattern portion propagates light 123 that varies in light intensity accordingly. In cross section, the light intensity varies according to the intensity pattern imparted by the patterned substrate 121.

[0029] In some embodiments, the light intensity measuring surface 111 may comprise an array of light sensing elements (an example of which is illustrated at 1803 in FIG. 5), each of which responds according to the intensity of light to which it is exposed. In one embodiment, the light intensity measuring surface 111 senses the image as an array of light sensor charge values ​​that vary from one light sensing element to the next according to the corresponding light intensity pattern to which the light intensity measuring surface 111 is exposed.

[0030] The microlens array 227 includes an array of microlenses (an example of which is illustrated in FIG. 2 ) disposed between the light intensity pattern object 120 and the light intensity measuring surface 111 of the imaging device 110. The microlens array 227 is configured with respect to the light intensity pattern object 120 such that each respective microlens views a corresponding respective portion of the light intensity pattern object 120 as a sub-image. In that sense, the microlens array 227 forms an array of sub-images. The microlens array 227 focuses the array of sub-images onto the light intensity sensing surface 111 of the imaging device 110 to form a sensed image of the light intensity pattern object 120 thereon.

[0031] The imaging device 110 can capture images from the light intensity sensing surface 111 to generate a sequence of captured images over time during which a displacement occurs or may occur. The imaging device 110 provides at least a first captured image (a "reference" image) and at least a second captured image (a "sensed" image) to the image registration processor 130. The image registration processor 130 measures the displacement by registering (aligning) the sensed image to the reference image of the light intensity pattern object 120.

[0032] In use, the light intensity pattern object 120 may be rigidly affixed to the first structure 1313, and the imaging device 110 comprising the light measurement surface 111 may be rigidly affixed to the second structure 1314. In some embodiments, the first structure 1313 and the second structure 1314 are separate structures, each having up to six degrees of freedom of movement (shown as eight). In other embodiments, the first structure 1313 and the second structure 1314 may be different structural portions of the same structure. The sensor 100 measures the relative displacement of the first structure 1313 with respect to the second structure 1314 by measuring the relative displacement of the light intensity pattern object 120 with respect to the imaging device 110.

[0033] In some embodiments, the sensor 100 comprises a flexible support structure that facilitates relative movement in at least one degree of freedom between the light intensity pattern object 120 and the imaging device 110, allowing relative movement therebetween.

[0034] In some embodiments, a substrate or mask is disposed on a support structure such that the support structure serves as the patterned substrate 121 for the light intensity pattern object 120. In one example, the patterned substrate is coated with or made from a material that fluoresces, and exposing the patterned substrate to light from a light source excites the patterned substrate to fluoresce (emit light), and the light emitted from the patterned substrate comprises the light intensity pattern for the light intensity pattern object 120.

[0035] In some embodiments, the light intensity pattern object 120 may include a mask with opaque and transparent regions, i.e., light-transmitting regions. In some embodiments, the mask may be fabricated using lithography processes such as those employed in the semiconductor manufacturing industry. Light from a light source may pass through the transparent regions while being blocked by the opaque regions, forming the light intensity pattern.

[0036] In some embodiments, the light intensity pattern may be formed using one or more light-emitting diode (LED) arrays. In some embodiments, the LED array may include organic LEDs (OLEDs). In some embodiments, the light intensity pattern may be formed using one or more quantum dot arrays. In some embodiments, a combination of LED arrays and quantum dot arrays may be used. In another embodiment, the light intensity pattern may be formed by an array of light valves. The array of light valves may function as controllable shutters, allowing for selective transmission or blocking of light. These valves may also allow for a percentage of light to be transmitted between completely blocking light, i.e., 0% transmission, and allowing all light to be transmitted, i.e., 100% transmission. In one example, the light intensity pattern may be formed by a liquid crystal display (LCD). An LCD may use a backlight and layers of valves to control the light emitted by each valve and therefore the light intensity pattern.

[0037] FIG. 2 shows more details of the sensor 100 depicted in FIG. 1 to facilitate an explanation of the configuration and cooperative interrelationship of the sensor components. Initially, the sensor 100 is configured such that each respective microlens of the microlens array 227 defines a corresponding respective microlens optical axis (representative examples are depicted at 60 and 61). Thus, the sensor 100 is a multi-optical axis sensor. In contrast, conventional displacement sensors typically rely on single-optical axis lens systems to focus an image of an object onto a light measurement surface. The sensor 100 offers advantages over conventional single-optical axis sensors. The multiple optical axes provided by the microlens array 227 allow the sensor 100 to be more compact than prior art sensors without sacrificing image quality. By maintaining higher image quality, improved displacement measurement resolution can be achieved. Image quality may be determined by the point spread function of the light pattern imaged on the imaging device, with relatively high image quality having a smaller point spread function than relatively low image quality. Image quality may additionally or alternatively be determined by the amount of edge blurring, with relatively less blurring being associated with relatively higher image quality than relatively lower image quality. Image quality may additionally or alternatively be determined by the amount of image distortion, with relatively less image distortion and / or aberration being associated with relatively higher image quality than relatively lower image quality.

[0038] 1 , imaging device 110 provides displacement measurement by registering a first image of light intensity pattern object 120 captured from light intensity measurement surface 111 to a second image of light intensity pattern object 120, which may be a reference image. To that end, imaging device 110 includes image registration processor 130. Image registration processor 130 is configured to spatially transform and align the first and second images using an image registration or image alignment algorithm. The spatial transformation provides a functional mapping that encodes the magnitude and direction of displacement of light intensity pattern object 120 relative to imaging device 110 that occurs between the capture of the sensed image (second image) and the capture of the reference image (first image).

[0039] Suitable image registration techniques can include light intensity-based techniques, feature-based techniques, and combinations thereof. Light intensity-based techniques register first and second images by comparing light intensity patterns, or sub-images, in the first and second images via correlation metrics. If sub-images or pattern portions are highly correlated, they can be considered to correspond to features or feature points in the sub-images. Feature-based registration techniques determine correspondences between features such as points, lines, edges, and contours in the first and second images. An "edge" is a set of contiguous pixels (light-sensitive elements) along which an abrupt change in light intensity value occurs, thereby defining a high-intensity gradient in the sub-image.

[0040] Based on the correspondence of the distinguishable features in the first and second images, a geometric transformation is determined that maps the first image to the second image based on the distinguishable features, thereby establishing a point-to-point correspondence between the first and second images. Methods that combine intensity-based information and feature-based information may also be used. Image registration methods are well known in the art.

[0041] Regardless of the registration method, the number and distribution of distinguishable features in the first and second images affect the accuracy of the registration. The more accurate the registration, the higher the resolution of the displacement measurement. Sensor 100 achieves high-resolution displacement measurements at least in part through a configuration and cooperative arrangement of components that increases the number and distribution of distinguishable features in the sensed image formed by light intensity measuring surface 111.

[0042] Referring again to FIG. 2 , it can be seen that each microlens 327 defines a corresponding optical axis (examples shown as 60 and 61) that is spatially separated from the optical axes of the remaining microlenses 327 that make up the array 227. Each respective optical axis intersects the light intensity pattern object 120 at a corresponding point on the surface of the light intensity pattern object 120. Each point is spatially separated from all other points. Each microlens views a portion 127 of the light intensity pattern object 120 about its own optical axis to form a corresponding spatially unique sub-image, or “sub-view,” of the light intensity pattern object 120. Each sub-image formed by a given microlens may be at least partially spatially distinct from the sub-images formed by all other microlenses. In some embodiments, each sub-image does not overlap with the other sub-images. In other embodiments, the sub-images may overlap.

[0043] Microlens array 227 focuses each sub-image onto light intensity measuring surface 111, thereby exposing surface 111 to focused light intensity variations corresponding to pattern portions within each spatially distinct sub-image. At the photosensor array of light intensity measuring substrate 111, the focused light intensity variations produce more abrupt transitions in charge values ​​compared to transitions that would be produced by unfocused sub-images.

[0044] In some embodiments, the light intensity pattern object 120 is designed so that there is enough irregularity in the pattern or uniqueness across portions of the pattern so that the image registration algorithm does not confuse two different displacements. In this way, the image registration algorithm, executed by the image registration processor, generates a single displacement solution for each possible displacement.

[0045] Spherical lenses produce higher-quality images when the image is formed within the paraxial region of the lens. See, for example, the paraxial regions depicted in Figures 6B and 6G. The image in Figure 6C resulting from a microlens array does not exhibit, or at least exhibits significantly less optical aberration than the image in Figure 6H resulting from a single-optical-axis imaging system when the distance between the object plane and the image plane is the same. Figure 6H illustrates two common optical aberrations: edge blurring and radial distortion. Sharp edges, such as the sharp transition between bright and dark regions shown in the resulting image in Figure 6C, have high gradients, as represented by the sharp edges in the intensity plot shown in Figure 6D and the exploded view in Figure 6E, which result in higher-resolution image registration. Gao et al. mathematically proved that high gradients result in higher-resolution image registration. (See Gao et al., "Displacement sensing and estimation theory and applications," Applied Physics A, 80(6), pp. 1265-1278.) Blurred edges, such as those shown in the region between the light and dark regions in Figure 6H, have a low gradient, represented by the smooth, gradual transition in the intensity plot shown in Figure 6I and the exploded view in Figure 6J, which substantially reduces the resolution of image registration. Additionally, radial distortion changes the image as the pattern moves, as different portions of the image have different amounts of radial distortion. This can be seen in Figure 6H, where the central portion of the image formed through the paraxial region shows no radial distortion, while portions of the image formed outside the paraxial region do. Because the pattern can move relative to the image sensor, radial distortion changes the shape of the image depending on where the pattern passes through the lens. This interferes with image registration algorithms and causes a substantial loss of resolution.

[0046] While the example in Figures 6A-6E shows a single row of three lenses for the microlens array for clarity, a microlens array may consist of hundreds or thousands of lenses, each imaging a small portion of the pattern. Thus, the field of view (dashed inverted triangle) shown in Figure 6B will be very small, whereas a single-optical axis system for the same object image distance shown in Figure 6G would be many times larger (by the number of lenses in the row). For example, if there were 100 lenses in a microlens array row and the field of view for the microlens array was 1 degree, the field of view for the single-optical axis imaging system would be 100 degrees, which typically produces a highly distorted image with blurred edges—an effect familiar to photographers. A 1-degree cone falls well within the high-quality paraxial range of a spherical lens. In some embodiments, the distortion, aberration, and blur associated with spherical lenses can be reduced by using aspheric lenses, but even with aspheric lenses, radial distortion is improved by imaging through the paraxial range.

[0047] 2 and 3 depict a 4×3 array of light intensity pattern portions 127. After reading this disclosure, it will be understood that this is but one of many suitable array dimensions. In some embodiments, the areas of patterned substrate 121 that are part of light intensity pattern object 120 (denoted by “w” and “h” in FIG. 2 ) overlap with microlens array 227 in all directions, so that no matter how much displacement there is, microlens array 227 still “sees” the light intensity pattern that it images onto light measurement surface 111. Thus, in embodiments in which microlens array 227 is affixed to light measurement surface 111, the light intensity pattern needs to be larger than microlens array 227 by the maximum desired displacement measurement.

[0048] Figure 3 depicts sensor 100 after rotation of light intensity pattern object 120 about z-axis 104 relative to the position depicted in Figure 2. When light intensity pattern object 120 is rotationally displaced relative to light measurement surface 111 as shown, the orientation of light intensity pattern portions (exploded view of exemplary portion 29) on light measurement surface 111 may correspondingly change. In the example depicted in Figure 3, after the displacement, the dark bars (shown in exploded view) that make up image element 29 have changed orientation on light measurement surface 111 relative to the orientation of the corresponding dark bars in image element 29 (shown in exploded view) depicted in Figure 2.

[0049] The image registration processor 130 (shown in FIG. 1) can map the "before image" (reference image) with their fixed positions on the light intensity measurement surface 111 (corresponding to the orientation of the edges in the image elements 29 in FIG. 2) to the "after image" (sensed image) with their fixed positions (corresponding to the orientation of the edges in the image elements 29 in FIG. 3). The mapping or transformation from one set of fixed pixel positions to another set of fixed pixel positions can indicate the magnitude and direction of the rotational displacement of the light intensity pattern object 120.

[0050] Figure 4A is a ray diagram of an exemplary double microlens element, also referred to as a doublet or more commonly a compound lens, suitable for use in an embodiment of microlens array 227 in which each lens element in the array includes two lenses as shown in Figure 4A. Figure 4B is a ray diagram of an exemplary single microlens element, also referred to as a singlet, suitable for use in an embodiment of microlens array 227 in which each lens element in the array includes a single lens. In other embodiments, a collimator (not shown) or one or more other optical components may be used to shape or direct light propagating in or from light intensity pattern object 120, thereby facilitating image registration.

[0051] 5 illustrates further details of the optical measurement surface 111 of the imaging device 110. The optical measurement surface 111 comprises an array 1801 of photodetector elements (an exemplary photodetector is shown at 1803). Each photodetector element 1803 in the array has a known fixed position on the optical measurement surface 111. The known fixed position may be specified by a coordinate in a coordinate system of the optical measurement surface 111.

[0052] Intensity-patterned light is incident on photodetector 1803, causing photodetector 1803 to respond to the photon flux. In some embodiments, a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) detector array accumulates charge depending on the intensity of the incident light and the time that photodetector 1803 is exposed to the photon flux. In a CCD imager embodiment, each p-doped MOS capacitor corresponds to an image element (pixel) that makes up the image of light intensity-patterned object 120.

[0053] The relative amount of charge from one individual photodetector to the next in the array 1801 varies according to variations in light intensity across the light intensity pattern object 120. The imaging device 110 captures an image of the light pattern object 120 by "reading" or measuring the charge level of each photodetector that makes up the light measurement surface 111. The imager electronics converts the charge levels into light intensity values. In the captured image, each photodetector element corresponds to a pixel specified by a light intensity value corresponding to the photodetector charge level and coordinates that define the fixed location of the pixel (photodetector element) on the light measurement surface 111.

[0054] While the above exemplary embodiments have been described using CCD or CMOS detector arrays, other detectors are possible in addition or alternatively. For example, a photoconductor may be used to measure photon flux, with the conductance of the photoconductor varying as a function of the photon flux incident on the detector. As another example, a reverse-biased photodiode varies the current flowing through the junction based on the photon flux (i.e., the intensity of light incident on the junction). As yet another example, a photodiode may be used in a photovoltaic mode, where information about the photon flux is captured as a current that drives the diode in the forward direction.

[0055] In one exemplary intensity measurement technique, the capacitor is biased above a threshold for inversion when light acquisition begins, allowing for the conversion of incident photons to electronic charges at the semiconductor-oxide interface. In other implementations, the imaging device 110 can include an N-type metal-oxide semiconductor (NMOS or LMOS) image sensor. Thus, the light measurement surface 111 of the imaging device 110 can include any suitable array of light-sensitive or light-detecting elements operable to sense light and charge to a level representative of the intensity of the sensed light, such as imaging sensors typically found in digital cameras, cell phones, webcams, and the like. The light-sensing elements 1803 can be of any suitable size, depending on the implementation.

[0056] In some embodiments, each light intensity pattern portion (e.g., 127) of patterned substrate 121 includes at least one relatively bright portion and at least one relatively dark portion to define at least one edge in each light intensity pattern portion 127. In the example patterns of FIGS. 2 and 3, each pattern portion 127 is defined by one or more black bars, each black bar being defined by two edges. In some exemplary embodiments, black patterns with non-parallel and / or curved edges may be used to address loss of displacement sensitivity that can occur when displacement occurs along the edges of a parallel bar pattern. However, these are exemplary embodiments. Those skilled in the art will recognize that a variety of suitable patterns fall within the scope of the present disclosure.

[0057] The pattern portions 127 extend along at least two axes of a coordinate system in which the patterned substrate 121 resides. The microlens array 227 focuses the pattern portions 127 onto the light detection surface 111 as a matrix of focused sub-images, which extend along at least one axis of the light measurement surface such that the focused, spatially distinct image portions are substantially uniformly distributed across the entire imaging area of ​​the light intensity measurement substrate 111. In some embodiments, the light intensity pattern within each pattern portion 127 is unique. For example, in array 1855, no two pattern portions are identical.

[0058] In some embodiments, each pattern portion 127 included in array 1855 corresponds to a particular predetermined pattern that may be provided to imaging device 110 prior to capturing an image of light intensity pattern object 120 to measure displacement. Alternatively, one or more sensed images of light intensity pattern object 120 may serve as reference or orientation images. These may be provided as input to registration processor 130 (illustrated in FIG. 1 ). In some embodiments, each pattern portion 127 is spatially unique, and each pattern portion 127 is uniquely identifiable by imaging device 110 or registration processor 130 by a unique pattern or tag. Each of the different, individually identifiable pattern portions may be known to imaging device 110 or processor 130 and may be referenced for calibration purposes or to measure displacement of light intensity pattern object 120 from an initial calibration position and / or orientation.

[0059] In some embodiments, the light intensity pattern object 120, the microlens array 227, and the imaging device 110 (and / or the light measurement surface 111) may be arranged to establish a nominal relative initial position. At those initial positions, the imaging device 110 may capture one or more reference images of the light intensity pattern object 120. One or more of the reference images may be provided to the image registration processor 130. The imaging device 110 may then capture a series of images of the light intensity pattern object 120 over time during which the light intensity pattern object 120 may be displaced. The one or more reference images and the series of images while the light intensity pattern object 120 is being displaced may be used to measure the displacement. In other embodiments, the reference image may be reset so that a new sensed image or images of the light intensity pattern object 120 may serve as a new reference image.

[0060] FIG. 7A is a perspective view of an embodiment of sensor 100 in which microlens array 227 is rigidly affixed to light intensity pattern object 120 (including patterned substrate 121 and light source 122). FIG. 7B is a perspective view of an alternative embodiment of sensor 100 in which microlens array 227 is rigidly affixed to imaging device 110. In both embodiments, patterned substrate 121 and light source 122 are fixed relative to one another. Structures, devices, or mechanisms for facilitating relative movement may be employed. Relative movement may be constrained to relative movement in only one or more selected degrees of freedom, such as translation along only the X axis and / or rotation about only the Z axis. Any suitable arrangement of imaging device 110 and light intensity pattern object 120 that facilitates relative movement of imaging device 110 and light intensity pattern object 120 in one or more desired degrees of freedom is intended to fall within the scope of the disclosed embodiments and appended claims.

[0061] In any of these embodiments, the components of sensor 100 may be configured as described above to provide high-resolution displacement measurements for up to three translational degrees of freedom of movement of light intensity pattern object 120 and / or optical measurement surface 111 along the X, Y, and Z axes (illustrated at 6) and up to three rotational degrees of freedom of movement of light intensity pattern object 120 and / or optical measurement surface 111 about the X, Y, and Z axes.

[0062] FIG. 8 shows an exemplary sensor 1100 configured to measure acceleration in one or more directions. Similar to the sensor illustrated in FIG. 1, the sensor 1100 includes a light intensity pattern object 1120 that includes a patterned substrate 1111. A microlens array 1127 is positioned between the light intensity pattern object 1220 and the light measurement surface 1111 of the imaging device 1110. The sensor 1100 additionally includes a mass 1180 coupled to the light intensity pattern object 1120. The mass 1180 and the light intensity pattern object 1120 are coupled to a support structure 1190 by a resilient member 1170. The resilient member 1170 can comprise a spring, which may be any suitable metallic spring, elastomeric spring, or other suitable resilient member, that facilitates relative movement of the imaging device 1110 and the light intensity pattern object 1120 in one or more degrees of freedom of movement.

[0063] 8 as being associated with mass 1180 and suspended by elastic member 1170, other arrangements are within the scope of the disclosed embodiments. For example, imaging device 1110, rather than light intensity pattern object 1120, can be associated with or coupled to mass 1180 and suspended from the support structure by elastic member 1170. In either arrangement, microlens array 1127 can be rigidly affixed to support structure 1190. Alternatively, microlens array 1127 can be rigidly affixed to imaging device 1110.

[0064] FIG. 9 illustrates a sensor 1200 configured as an extensometer to measure strain. In this exemplary embodiment, an imaging device 1210 is fixed to a surface 1213 at location 1214, and a light intensity pattern object 1220 is fixed to the surface 1213 at location 1215. When the surface 1213 is subjected to a strain or warping force, the imaging device 1210 and the light object 1220 move relative to one another. The resulting displacement may serve to facilitate measuring strain in one or more degrees of freedom. For example, over a given time interval, the displacement of the imaging device 1210 relative to the light intensity pattern object 1220 in the region of location 1215 may be different from the displacement of the imaging device 1210 relative to the light intensity pattern object 1220 in the region of location 1214. The difference in displacement in region 1215 and region 1214 is reflected in a corresponding change in the position and size of the light pattern portions included in the array of images formed on the optical measurement surface 1211. In other words, the light pattern contained in an image of the light intensity pattern object 1220 captured before the time it was subjected to the distortion or warping force is different from the light pattern contained in an image of the light intensity pattern object 1220 captured after it was subjected to the distortion or warping force. The difference in the light intensity pattern portions in the first and second images, which are passed to the image registration processor 130 in Figure 1, results in a measurement of the displacement between the times the first and second images were acquired. In this example, this displacement can be used to measure the distortion or warping.

[0065] In this application, as with other applications disclosed herein, the microlens array 1227 may be rigidly affixed to either the light intensity pattern object 1220 or the imaging device 1210, as shown in Figures 7A and 7B. Those skilled in the art will recognize that strain gauges are merely one example of sensors enabled by the technology described herein. As such, this particular application is not intended to be limiting in any way.

[0066] 8 and 9 provide exemplary embodiments of sensor 100 configured to measure acceleration, such as linear acceleration, and as an extensometer to measure strain. These examples are not intended to be limiting. For example, sensor 100 may be configured to measure rotational rate, such as that measured by a gyroscope. Additionally, sensor 100 may be configured to measure any one or more of strain, force, and torque.

[0067] 10A-10D illustrate the relative translational and rotational motion of components of a sensor 1300 according to an alternative embodiment. The sensor 1300 includes all of the components described above with respect to FIG. 1 and is configured to measure any of a number of displacement-derived parameters, including acceleration and strain. FIGS. 10A-10D illustrate first and second housings 1320 and 1310 that can house the components of the sensor 100 shown in FIG. 1, for example. For example, the first housing 1320 can house the light intensity pattern object 120 (an example of which is illustrated in FIG. 1). The second housing 1310 can house the imaging device 110 (an example of which is illustrated in FIG. 1). The microlens array 127 (an example of which is illustrated in FIG. 1) can be rigidly affixed to the light intensity pattern object 120 and housed within the first housing 1320, or can be rigidly affixed to the imaging device 110 and housed within the second housing 1310.

[0068] 1 , the sensor 1300 further includes a transparent elastic member 1301 disposed between a first housing 1320 (enclosing the light intensity pattern object 110) and a second housing 1310 (enclosing the imaging device 110). In one embodiment, the elastic member 1370 includes a silicone layer 1301 configured to hold the housings 1320 and 1310 in a spaced-apart configuration, thereby holding the light intensity pattern object 120 and the imaging device 110 in a corresponding spaced-apart configuration.

[0069] In one exemplary implementation, the polymer layer 1301 includes a polymer suspension, thereby providing a polymer suspension system for the imaging device 1310 and the light intensity pattern object 1320. In one implementation, the light intensity pattern object 1320 includes one or more light sources (one example is illustrated in FIG. 1 at 122), and the elastic member 1301 is disposed outside the one or more light sources 122.

[0070] In some embodiments, the microlens array 227 is rigidly affixed to the light intensity pattern object 120 or to its supporting substrate, as illustrated in Figure 7A. In that embodiment, the light intensity pattern object 120 and the microlens array 227 may be housed together in a first housing 1320. In other embodiments, the microlens array 227 is rigidly affixed to the imaging device 110, as illustrated in Figure 7B. In those embodiments, the imaging device 110 and the microlens array 227 may be housed together in a second housing 1310.

[0071] The polymer layer 1301 is compressible and extensible to facilitate relative movement of the imaging device 1310 and the light intensity pattern object 1320 with multiple degrees of freedom. For example, FIG. 10A illustrates translation of the light intensity pattern object 1320 relative to the imaging device 1310 along the y-axis. FIG. 10B illustrates translation of the light intensity pattern object 1320 relative to the imaging device 1310 along the x-axis. FIG. 10C illustrates rotation of the light intensity pattern object 1320 about the y-axis relative to the imaging device 1310. FIG. 10D illustrates rotation of the light intensity pattern object 1320 relative to the imaging device 1310 about the x-axis. Variations within the scope of the disclosed embodiments include configurations in which the imaging device 1310, rather than the light intensity pattern object 1320, translates or rotates as described above. Although not depicted, translation along the z-axis, rotation about the z-axis, or any combination of translation along or rotation about any of three orthogonal axes are possible.

[0072] The transparent polymer layer 1301 can establish a nominal separation distance and orientation between the first housing 1320 and the second housing 1310, thereby establishing a corresponding nominal separation distance and orientation between the light intensity pattern object 120 and the imaging device 110. In some embodiments, the nominal separation distance and orientation define a starting position of the light intensity pattern object 120 and the imaging device 110, and displacement can be measured by referencing the nominal starting position.

[0073] For example, the first housing 1320 may be affixed to the first structure 1313, or a portion thereof, and the second housing 1310 may be affixed to the second structure 1314, or a portion thereof. At the time of attachment or affixation, the imaging device 110 may capture one or more reference or calibration images of the light intensity pattern object 120. Over a subsequent period of time, the imaging device 110 may capture a series of images of the light intensity pattern object 120. The images captured during the subsequent period are registered to the previously captured reference image(s), thereby generating absolute displacement measurements from the time of attachment, which may provide more accurate registration and facilitate making higher resolution displacement measurements.

[0074] In some applications, a first housing 1320, which rigidly holds the light intensity pattern object 120 therein, is affixed to the first structure 1313. A second housing 1310, which rigidly holds the imaging device 130 therein, is affixed to the second structure 1314. As described above, the microlens array 227 can be rigidly held in either the first or second housing. Either the first structure, the second structure, or both structures can move with up to six degrees of freedom. Movement of either or both structures exerts corresponding forces on the first and second housings in any of up to six degrees of freedom of movement. Either or both of the first and second housings, and therefore either or both of the light intensity pattern object 1320 and the imaging device 1310, can move in response to these applied forces. As a result, corresponding forces are exerted on the elastic layer 1301. The elastic layer 1301 responds to these forces in any one or more of the six degrees of freedom of movement.

[0075] Regardless of the direction of relative displacement of the first housing 1320 (and therefore the light intensity pattern object 120) with respect to the second housing 1310 (and therefore the imaging device 110), and regardless of whether the microlens array 227 is rigidly affixed to the light intensity pattern object 120 (or the first housing 1320) or, alternatively, to the imaging device 110 (or the second housing 1310), the components are arranged and configured such that the microlens array 227 forms a sub-image of a portion of the light intensity pattern object 120 and focuses the sub-image as a matrix of image elements onto the light measurement surface 111 of the imaging device 110 (one example is shown in FIG. 1), thereby facilitating registration of the sensed image of the light intensity pattern object 110 and enabling high-resolution displacement measurements. The position, size, and / or shape of the pattern portions within the image element can change from one sensed image to the next according to changes in the orientation of the first housing 1320 relative to the second housing 1310 due to forces exerted by the displacement of the first structure relative to the second structure and corresponding expansion and / or compression of various portions of the elastic layer 1301.

[0076] FIG. 11 illustrates a sensor 1400 according to the present disclosure. The sensor 1400 comprises an imaging device 1410 including an optical measurement surface 1411. The optical measurement surface 1411 includes an array of photosensor elements (an example of which is illustrated at 1803 in FIG. 5 ). The imaging device 1410 is positioned proximate to a patterned substrate 1448. The patterned substrate 1448 is affixed to a support structure 1440. The patterned substrate 1448 can move with up to six degrees of freedom, as depicted at 8. A microlens array 1427 is disposed between the patterned substrate 1448 and the imaging device 1410. The microlens array 1427 can be rigidly affixed either to the imaging device 110, as shown in FIG. 7B, or to the patterned substrate 1448. In embodiments in which patterned substrate 1448 is rigidly affixed to support structure 1440 as shown in FIG. 7A, microlens array 1427 may be rigidly affixed to support structure 1440 .

[0077] FIG. 11 depicts, among other things, an exemplary implementation of the light intensity pattern object 120 of the sensor 100 depicted in FIG. 1. The light intensity pattern object 120 in FIG. 1 can include a light source 1462 supported by a light support structure 1460, the light source 1462 operable to generate and direct light 1464 onto the patterned substrate 1448. In FIG. 11, the light source 1462 is depicted as being stationary relative to the imaging device 1410. Alternatively, although not depicted, the light source 1462 can be configured to be stationary relative to the patterned substrate 1448. The light directed onto the patterned substrate 1448 is transmitted or attenuated according to the light intensity pattern. The light intensity pattern is sensed by a photosensor of the light measurement structure 1411 of the imaging device 1410 to determine relative movement between the imaging device 1410 and the patterned substrate 1448.

[0078] In some exemplary embodiments, the patterned substrate 1448 includes an excitable material. For example, the patterned substrate 1448 can include a fluorescent coating or material, and the light source 1462 is operable with the sensor 1400 to direct light (e.g., UV light) toward and onto the patterned substrate 1448, causing the patterned substrate 1448 to fluoresce and propagate light that is detectable by the imaging device 1410 as a light intensity pattern.

[0079] In an exemplary embodiment, the sensor 1400 is operable in ambient light (light that is diffuse and not necessarily directional in nature, or that is specifically provided for the purpose of facilitating the operation of the sensor 1400), which illuminates the patterned substrate 1448 or illuminates the substrate material such that the light pattern formed by the patterned substrate can be sensed under ambient light conditions. In one example, the light pattern formed by the patterned substrate can be sensed by a photosensor that constitutes the light measurement surface 111 of the imaging device 110 as depicted in FIG. 1 . Ambient light can include natural light (e.g., sunlight) or artificial light (powered light). The source of the ambient light can be located anywhere with respect to the sensor. The intensity and / or other characteristics of the ambient light can be such that features of the substrate 1448 and the pattern can be defined and identified so as to be recognizable to the imaging device 1410.

[0080] The patterned substrate 1448 may be formed from a fluorescent light-emitting material or may include a fluorescent light-emitting coating. The light source 1462 may be disposed about a side of the sensor 1400 that is common with the imaging device 1410, and the light source 1462 and imaging device 1410 may be powered from the same common side. In one aspect, the light source support structure 1460 that supports the light source 1462 may comprise the same structure 1480 that supports or to which the imaging device 1410 is affixed. In some embodiments, the light source support structure 1460 is attached to a first structure 1480 whose displacement relative to the second structure is to be measured. The structure 1440 may be attached to a second structure 1490. In other embodiments, the structure 1460 and the structure 1480 may comprise different structures.

[0081] In one aspect of the technology described herein, the light source 1462 can include a UV light source operable to propagate light at wavelengths ranging from about 315 to about 400 nanometers. In another aspect, the light source 1462 can emit UV light at wavelengths in the mid-wave (290-315 nm) or far-wave (190-290 nm) UV field. Other types of light emission methods and systems are contemplated for use on or with the patterned substrate 1448, such as phosphorescence and chemiluminescence. In a further embodiment, the light source 1462 can illuminate a light diffuser attached to a mask, such as the exemplary mask described above that includes opaque and transparent regions, to generate a light intensity pattern. The above is merely an example and is not intended to be limiting. The light source can be used in any suitable manner to illuminate an object and form a light intensity pattern.

[0082] 12 is a flowchart illustrating a method 1200 according to one embodiment disclosed herein. At 1205, a microlens array forms a spatially distinct array of sub-images of a light intensity pattern object. At 1210, the microlens array focuses the spatially distinct array of sub-images onto a light measurement surface of an imaging device as a sensed image of the light intensity pattern object.

[0083] At 1215, an imaging device captures sensed images of the light intensity pattern object. At 1220, an image registration processor of the imaging device registers at least one sensed image to the reference image based on pattern portions in the spatially distinct focused sub-images. In some embodiments, a subset of the spatially distinct focused sub-images may be used for registration, which can reduce computation time at the possible cost of lower measurement resolution.

[0084] At 1225, a registration processor performs a measurement of the displacement of the light intensity pattern object relative to the imaging device based on the registration.

[0085] 13 is a flowchart illustrating a method 1300 according to one embodiment disclosed herein. At 1305, a light intensity pattern object, a microlens array, and an imager (also referred to herein as an "imaging device") are provided. The microlens array is disposed between the light intensity pattern object and the imager. The light intensity pattern object may be provided with the microlens array affixed thereto. In an alternative embodiment of method 1300, the provided imager may include a microlens array affixed thereto.

[0086] At 1310, the light intensity pattern object 120 is affixed to a first structure whose displacement relative to a second structure is to be measured. At 1315, an imager is affixed to the second structure.

[0087] At 1320, the microlens array forms an image of the light intensity pattern object. The image includes an array of spatially distinct sub-images.

[0088] At 1330, the microlens array focuses the spatially distinct sub-images onto the light intensity measuring surface of the imager, thereby forming a sensed image of the light intensity pattern object.

[0089] At 1335, the imager captures a sensed image from the light intensity measurement surface. At 1340, the imager registers the sensed image to the reference image to provide a measurement of the displacement of the light intensity pattern object from a position and / or orientation of the light intensity pattern object defined by the reference image.

[0090] In some embodiments, imager 110 captures a series of sensed images of light intensity pattern object 120 over a period of time. In that embodiment, the reference image can include a sensed image within the series of sensed images. In some embodiments, the reference image is any image within the series of sensed images, and the reference image can change from one period to the next.

[0091] In some embodiments, a series of images may be used to calibrate sensor 100. For example, two images resulting from a known displacement, a known strain, or a known acceleration may be used. Through registration, the relative displacement between the two images may be used to calibrate sensor 100 based on the known displacement, strain, acceleration, etc.

[0092] Although the exemplary embodiments of the sensor disclosed herein generally depict a light intensity pattern object used to generate a light intensity pattern that is viewed directly by a microlens array that focuses the light intensity pattern as an image directly onto an imaging device, this is not intended to be limiting. Furthermore, stated differently, the light intensity pattern object is generally depicted as facing toward the imaging device. Alternatively, by using one or more mirrors, the light intensity pattern object could face any direction, including facing the same direction as the imaging device. In one example, by using one or more mirrors, the light intensity pattern object could be affixed to the same structure as the imaging device using one or more mirrors. In another example, one or more mirrors could be used to reflect the light intensity pattern toward the microlens array. Additionally or alternatively, one or more mirrors could be used to reflect light from the microlens array, which forms an image on the imaging device.

[0093] It is to be understood that embodiments of the present disclosure are not limited to the particular structures, process steps, or materials disclosed herein, but extend to equivalents thereof as understood by those skilled in the relevant arts. It is also to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0094] Throughout this specification, the reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, the appearance of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification does not necessarily all refer to the same embodiment. Features described with respect to one embodiment are not mutually exclusive. Rather, one skilled in the art will recognize that features of one embodiment can be readily combined with features from other embodiments.

[0095] As used herein, a plurality of items, structural elements, compositional elements, and / or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list were individually identified as a separate and unique member. Accordingly, any individual member of such a list should not be construed as a de facto equivalent of other members of the same list solely based on their presentation within a common grouping, absent indications to the contrary. In addition, various embodiments and examples of the present disclosure may be referenced herein, along with alternative forms of its various components. It is understood that such embodiments, examples, and alternative forms should not be construed as de facto equivalents of each other, but should be considered separate, autonomous expressions of the present disclosure.

[0096] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. The description provides numerous specific details, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. However, one skilled in the art will recognize that the invention can be practiced without one or more of the specific details, or by using other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0097] While the foregoing examples illustrate the principles of the present disclosure in one or more particular applications, it will be apparent to those skilled in the art that numerous modifications in the form of implementation, method of use, and details can be made without the exercise of inventive talent and without departing from the principles and concepts of the present invention. Accordingly, the present invention is not intended to be limited except as by the claims that follow. [Explanation of symbols]

[0098] 100 Displacement Sensor 110 Imaging Devices 110 Imager 111 Light Intensity Measuring Surface 120 Light Intensity Pattern Object 121 Patterned substrate 122 Light source 123 light 127 part 130 Image Registration Processor 227 Microlens Array 327 Microlens 1100 Sensor 1110 Imaging Device 1111 Patterned substrate 1120 Light Intensity Pattern Object 1127 Microlens Array 1170 Elastic member 1180 Mass 1190 Support structure 1200 methods 1210 Imaging Device 1213 Surface 1214 Placement 1215 Placement 1220 Light Intensity Pattern Object 1300 Sensor 1300 methods 1301 Transparent elastic material 1310 Second Housing 1313 First Structure 1314 Second Structure 1320 First Housing 1370 Elastic member 1400 Sensor 1410 Imaging Device 1411 Light measurement surface 1427 Microlens Array 1440 Support Structure 1448 Patterned substrate 1460 Optical support structure 1462 light source 1480 First Structure 1490 Second Structure 1801 Array 1803 Photodetector Element 1855 Multidimensional Array

Claims

1. 1. An apparatus for measuring displacement, comprising: a light intensity pattern object; an imaging device comprising a light intensity measuring surface; a microlens array disposed between the light intensity pattern object and the light intensity measuring surface, wherein each respective microlens of the microlens array views a corresponding respective portion of the light intensity pattern object as a sub-image, and each microlens of the microlens array focuses each respective sub-image onto the light intensity measuring surface, such that the microlens array forms an array of focused sub-images that form a sensed image of the light intensity pattern object on the light intensity measuring surface; Equipped with the imaging device is configured to capture the sensed image and register the sensed image to a reference image of the light intensity pattern object based on a portion of a pattern in the focused sub-image, thereby providing a measurement of displacement of the light intensity pattern object relative to the imaging device.

2. 2. The apparatus of claim 1, wherein the imaging device is configured to register the sensed image to the reference image at least in part by an image registration algorithm that maps portions of the pattern in the focused sub-image to portions of a corresponding pattern in the reference image.

3. The apparatus of claim 1 , wherein the microlens array is rigidly attached to the light intensity pattern object.

4. The apparatus of claim 1 , wherein the microlens array is rigidly affixed to the imaging device.

5. 2. The apparatus of claim 1, wherein the light intensity pattern object includes a patterned substrate that defines a light intensity pattern, the light intensity pattern being unique for each displacement of the light intensity pattern object relative to the imaging device such that an image registration processor generates a single displacement solution for each possible displacement.

6. 10. The apparatus of claim 1, wherein each respective sub-image corresponds to a central axis of a respective corresponding microlens in the microlens array such that each sub-image is spatially distinct from all other sub-images.

7. 10. The apparatus of claim 1, wherein the light intensity pattern object comprises a light source that produces diffuse light and a mask that includes transparent and opaque regions.

8. The apparatus of claim 1 , wherein the light intensity pattern object comprises a UV light source and a fluorescent material, the UV light source exciting the fluorescent material.

9. The apparatus of claim 1 , wherein the light intensity pattern object comprises a phosphorescent material.

10. The apparatus of claim 1 , wherein the light intensity pattern object comprises a chemiluminescent material.

11. The apparatus of claim 1 , wherein the light intensity pattern object comprises at least a light emitting diode (LED) array or a quantum dot array.

12. 10. The apparatus of claim 1, wherein the light intensity pattern object comprises an array of light valves.

13. The apparatus of claim 1 , wherein the light intensity pattern object and the imaging device are configured to measure distortion.

14. The apparatus of claim 1 , wherein the light intensity pattern object and the imaging device are configured to measure a force.

15. The apparatus of claim 1 , wherein the light intensity pattern object and the imaging device are configured to measure torque.

16. The apparatus of claim 1 , wherein the light intensity pattern object and the imaging device are configured to measure acceleration in one or more directions.

17. The apparatus of claim 1 , wherein the light intensity pattern object and the imaging device are configured to measure rotational speed.

18. The apparatus of claim 1 , wherein the light intensity pattern object and the imaging device are configured to measure a rotation angle.

19. The apparatus of claim 1 , wherein the light intensity pattern object and the imaging device are configured to measure at least one of a multi-axial force or moment.

20. 1. A method for measuring displacement, comprising: forming an array of spatially distinct sub-images of a light intensity pattern object based on a light intensity pattern of the light intensity pattern object, the light intensity pattern object comprising a patterned substrate configured as a multidimensional array of portions of a light intensity pattern that define the light intensity pattern of the light intensity pattern object; focusing the array of spatially distinct sub-images onto a light intensity measuring surface of an imaging device as an array of focused spatially distinct sub-images that form a composite sensed image of the light intensity pattern object; registering a composite sensed image to a reference image of the light intensity pattern object based on pattern portions in the focused spatially distinct sub-images, thereby enabling measurement of displacement of the light intensity pattern object relative to the imaging device; A method comprising:

21. A method as described in claim 20, wherein the registration step includes mapping pattern portions in the sub-image of the composite sensor image to corresponding pattern portions in the corresponding sub-image of the reference image, the pattern portions including at least one of light intensity pattern portions or feature-based pattern portions.

22. 21. The method of claim 20, wherein the light intensity pattern object comprises a light source that produces diffuse light and a mask that includes transparent and opaque regions.

23. 21. The method of claim 20, wherein the light intensity pattern object comprises a UV light source and a fluorescent material, the UV light source exciting the fluorescent material.

24. 21. The method of claim 20, wherein the light intensity pattern object comprises a phosphorescent material.

25. 21. The method of claim 20, wherein the light intensity pattern object comprises a chemiluminescent material.

26. 21. The method of claim 20, wherein the light intensity pattern object comprises at least a light emitting diode (LED) array or a quantum dot array.

27. 21. The method of claim 20, wherein the light intensity pattern object comprises an array of light valves.

28. The method of claim 20 further comprising measuring distortion based on the registration.

29. 21. The method of claim 20, further comprising measuring a force based on the registration.

30. 21. The method of claim 20, further comprising measuring torque based on the registration.

31. 21. The method of claim 20, further comprising measuring acceleration in one or more directions based on the registration.

32. 21. The method of claim 20, further comprising measuring a rotational rate based on the registration.

33. The method of claim 20, further comprising measuring a rotation angle based on the registration.

34. 21. The method of claim 20, further comprising measuring at least one of a multi-axial force or a moment based on the registration.

35. 1. An apparatus for measuring relative displacement, comprising: an imaging device comprising a light intensity measuring surface; a light intensity pattern object configured to propagate a light intensity pattern toward the light intensity measurement surface, the light intensity pattern characterized by variations in light intensity along a cross section defined by one or more axes of a light pattern object coordinate system; an array of microlenses disposed between the light intensity pattern object and the light intensity measuring surface such that each microlens in the array forms a sub-image of a corresponding portion of the light intensity pattern, the microlenses focusing the sub-images onto the light intensity measuring surface as an array of focused sub-images forming a sensed image of the light intensity pattern; Equipped with An apparatus whereby the displacement of the light intensity pattern object can be determined by registering the sensed image to a reference image.

36. 36. The apparatus of claim 35, wherein the array of microlenses is rigidly affixed to the light intensity pattern object.

37. 36. The apparatus of claim 35, wherein the array of microlenses is rigidly affixed to the imaging device.

38. 36. The apparatus of claim 35, wherein each microlens comprises at least two lenses aligned on the same optical axis.

39. 36. The apparatus of claim 35, wherein the light intensity pattern object comprises a light source that produces diffuse light and a mask that includes transparent and opaque regions.

40. 36. The apparatus of claim 35, wherein the light intensity pattern object comprises a UV light source and a fluorescent material, the UV light source exciting the fluorescent material.

41. 36. The apparatus of claim 35, wherein the light intensity pattern object comprises a phosphorescent material.

42. 36. The apparatus of claim 35, wherein the light intensity pattern object comprises a chemiluminescent material.

43. 36. The apparatus of claim 35, wherein the light intensity pattern object comprises at least a light emitting diode (LED) array or a quantum dot array.

44. 36. The apparatus of claim 35, wherein the light intensity pattern object comprises an array of light valves.

45. 36. The apparatus of claim 35, wherein the light intensity pattern object and the imaging device are configured to measure distortion.

46. 36. The apparatus of claim 35, wherein the light intensity pattern object and the imaging device are configured to measure a force.

47. 36. The apparatus of claim 35, wherein the light intensity pattern object and the imaging device are configured to measure torque.

48. 36. The apparatus of claim 35, wherein the light intensity pattern object and the imaging device are configured to measure acceleration in one or more directions.

49. 36. The apparatus of claim 35, wherein the light intensity pattern object and the imaging device are configured to measure rotational speed.

50. 36. The apparatus of claim 35, wherein the light intensity pattern object and the imaging device are configured to measure a rotation angle.

51. 36. The apparatus of claim 35, wherein the light intensity pattern object and the imaging device are configured to measure at least one of a multi-axial force or moment.

52. 1. A method for measuring relative displacement, comprising: focusing a light intensity pattern onto a light intensity measuring surface of an imaging device to form an image of the object using a plurality of lens elements, each lens element including one or more lenses and each lens element having a respective optical axis; measuring displacement of the object relative to the imaging device by registering a sensed image of the object to a reference image of the object based on the light intensity pattern.

53. 53. The method of claim 52, wherein registration comprises comparing a plurality of portions of the light intensity pattern in the sensed image with a plurality of corresponding portions of the light intensity pattern in a reference image of the object.

54. 53. The method of claim 52, further comprising generating the light intensity pattern using a light source that produces diffuse light and a mask that includes transparent and opaque regions.

55. 53. The method of claim 52, further comprising generating the light intensity pattern using a UV light source and a fluorescent material, wherein the UV light source excites the fluorescent material.

56. 53. The method of claim 52, further comprising generating the light intensity pattern using phosphorescent material.

57. 53. The method of claim 52, further comprising generating the light intensity pattern using a chemiluminescent substance.

58. 53. The method of claim 52, further comprising generating the light intensity pattern using at least a light emitting diode (LED) array or a quantum dot array.

59. 53. The method of claim 52, further comprising generating the light intensity pattern using an array of light valves.

60. 53. The method of claim 52, further comprising measuring distortion based on the registration.

61. 53. The method of claim 52, further comprising measuring a force based on the registration.

62. 53. The method of claim 52, further comprising measuring torque based on the registration.

63. 53. The method of claim 52, further comprising measuring acceleration in one or more directions based on the registration.

64. 53. The method of claim 52, further comprising measuring a rotational rate based on the registration.

65. 53. The method of claim 52, further comprising measuring a rotation angle based on the registration.

66. 53. The method of claim 52, further comprising measuring at least one of a multi-axial force or a moment based on the registration.

Images