Lidar

Abstract

A lidar includes a two-part objective for imaging a target and directing a probe beam to the target. A portion of a tracking beam that degrades the target image is attenuated with a dichroic filter that blocks a central portion of the tracking beam. A local oscillation beam can be generated with a hybrid lens that directs the probe beam through a polarizing beamsplitter to be focused at or on a waveplate so that a portion is reflected from the waveplate as the local oscillation beam. An imaging system that is confocal with the probe beam is coupled to provide a target measurement or to establish a focal point of the probe beam.

Description

Technical Field

[0001] This disclosure relates to lidar and laser tracking systems, optical systems and components for such systems, as well as associated measurement methods and apparatus. Background Technology

[0002] LiDAR systems typically estimate object distance based on the detection of a portion of the returning beam. A heterodyne system, using a mixture of the returning beam and a local oscillation signal, provides high-sensitivity detection and estimates distance based on the frequency difference between the measured returning beam and the local oscillation. By emitting a beam with appropriate chirp, these measurements can be performed even in the presence of object motion that could cause a Doppler shift.

[0003] In practical implementation, the camera images the target surface that receives the probe (measurement) beam and the pointing (or tracking) beam used for visual alignment. The camera includes lenses adjusted to produce an image of the target, and separate adjustable lenses are used to image the probe and tracking beams onto the target. Using different lenses for the visible / visible image and a beam-focusing lens for the IR probe beam allows for a simple lens design. Unfortunately, using two movable lenses requires translation or other stages for each and makes it difficult to maintain alignment between the camera axis and the probe beam axis. Furthermore, misalignment makes it difficult to use the camera image for anything other than coarse visual alignment.

[0004] Other challenges of heterodyne lidar are based on variations in the path length between the signal path and the local oscillation (LO) path associated with the object being measured. These LO path variations not only introduce ranging errors but also signal variations due to changes in the relative polarization state between the returning probe beam and the LO beam. For example, reflections through optical components such as metallic or dielectric mirrors or beam splitters can introduce phase shifts between different polarization states. This variation can reduce range sensitivity or lead to leakage, i.e., complete signal loss.

[0005] Practical applications of lidar typically require alignment with the part being measured, and necessitate placing one or more sets of machining balls around the part. This setup can be slow, limiting the rate at which the part can be measured. Therefore, improvements are needed. Summary of the Invention

[0006] The apparatus includes a dichroic beamsplitter and an optical fiber positioned to guide a probe beam along an axis to the dichroic beamsplitter. An objective lens is positioned on the axis and includes a fixed lens and a movable lens positioned to receive the probe beam from the dichroic beamsplitter. An image sensor is optically coupled to the dichroic beamsplitter and positioned on the axis to receive an imaging beam from a target via the dichroic beamsplitter, wherein the movable lens is translational to form an image of the target at the image sensor and to focus the probe beam on the target. In some examples, the dichroic beamsplitter is positioned such that the probe beam is transmitted through the dichroic beamsplitter to the movable lens, and the imaging beam is reflected by the dichroic beamsplitter to the image sensor. In other examples, the objective lens is positioned to receive a tracking beam from the dichroic beamsplitter and guide both the probe beam and the tracking beam to the target, wherein the probe beam has a wavelength between 1200 nm and 1800 nm, and the tracking beam has a wavelength between 400 nm and 700 nm. In some alternatives, the dichroic beam splitter is positioned such that the probe beam is reflected by the dichroic beam splitter to a movable lens, and the imaging beam is transmitted by the dichroic beam splitter to an image sensor. In typical embodiments, the dichroic beam splitter is a cubic dichroic beam splitter, a plate dichroic beam splitter, or a double-reflection dichroic beam splitter.

[0007] In another embodiment, the dichroic beamsplitter is a double-reflection dichroic beamsplitter, which includes a first surface facing a movable lens and a dichroic reflective surface. The dichroic reflective surface is positioned to guide an imaging beam to an image sensor and to guide a portion of a probe beam returning from a target to an optical fiber. In another embodiment, the dichroic beamsplitter is a double-reflection dichroic beamsplitter, which includes a first surface facing a movable lens and a dichroic reflective surface. The dichroic reflective surface is positioned to guide an imaging beam to the first surface such that the imaging beam is reflected by the first surface to the image sensor, and a portion of the probe beam returning from a target to the optical fiber is transmitted to the optical fiber by the reflective surface. In yet another example, the dichroic beamsplitter is a double-reflection dichroic beamsplitter, which includes a first surface facing a movable lens and a dichroic reflective surface. The dichroic reflective surface is positioned to guide a portion of the probe beam returning from a target to the first surface, and the imaging beam is transmitted to the image sensor by the dichroic reflective surface. In other representative examples, the first surface is positioned relative to the imaging beam received from the dichroic reflective surface at an angle greater than a critical angle, and the dual-reflection dichroic beam splitter includes an output surface positioned such that a portion of the probe beam returning from the target and reflected by the dichroic reflective surface to the first surface is reflected to be perpendicularly incident on the output surface. In some embodiments, the dual-reflection dichroic beam splitter includes a first prism having an apex angle β between the first surface and the dichroic reflective surface, wherein the apex angle β is greater than sin-1 (1 / n), where n is the refractive index of the prism. According to some examples, the dichroic reflective surface of the double-reflective dichroic beam splitter is defined on the surface of a first or second prism. In some cases, the double-reflective prism includes a first and second prism fixed to each other at corresponding mating surfaces, and the dichroic reflective surface is positioned at the mating surfaces. In some specific examples, the dichroic reflective surface is defined on at least one of the mating surfaces.

[0008] In other alternatives, the dichroic beam splitter includes a dichroic plate and a plane reflector, wherein the dichroic plate is positioned to guide the portion of the probe beam returning from the target to the plane reflector and to transmit the imaging beam to the image sensor. In still other examples, the dichroic beam splitter includes a dichroic plate and a plane reflector, wherein the dichroic plate is positioned to reflect the imaging beam to the plane reflector and to transmit the portion of the probe beam returning from the target.

[0009] In some representative examples, the optical fiber is a polarization-preserving single-mode (PRSM) fiber and also includes a polarization beamsplitter (PBS) positioned such that a probe beam from the PRSM fiber is received by the PBS in a polarization state (typically linear polarization) that is substantially transmitted from the PBS to the dichroic beamsplitter. The apparatus may include a waveplate positioned between the PBS and the dichroic beamsplitter to generate a circularly polarized state in the probe beam and to reflect a portion of the probe beam toward the fiber to generate a locally oscillating beam. In other examples, the waveplate has an input surface positioned to receive the probe beam from the PBS and an output surface positioned to receive the probe beam from the input surface of the waveplate. One of the input or output surfaces is coated with an antireflective coating, while the other of the input and output surfaces reflects a portion of the probe beam as a locally oscillating beam.

[0010] Typically, a hybrid lens is positioned to receive a measurement beam from an optical fiber, and a dichroic filter is positioned along an axis on the axial portion of the hybrid lens, transmitting the measurement beam and substantially not transmitting the tracking beam. In other examples, the dichroic filter is a dichroic reflector that transmits the measurement beam and reflects the tracking beam. In some examples, the dichroic filter is a wavelength-dependent polarizer that substantially does not transmit the tracking beam. According to a representative embodiment, a dichroic reflector is positioned along the axis on the axial portion of the hybrid lens, transmitting the measurement beam and reflecting the tracking beam, wherein the size of the dichroic reflector is based on the corresponding size of the image sensor. In some embodiments, the hybrid lens is positioned to receive the measurement beam and focus the measurement beam within a beam angular diameter α. A dichroic reflector is positioned along the axis on the axial portion of the hybrid lens, transmitting the measurement beam and reflecting the tracking beam, wherein the size of the dichroic reflector is based on the corresponding size of the image sensor. In a representative example, the size of the dichroic reflector is at least 0.5, 0.75, 1.0, or 1.5 times the product of the corresponding size of the image sensor and the ratio of the optical distance along the axis from the focal point of the mixing lens to the optical distance from the focal point of the mixing lens to the image sensor. For convenience, the dichroic filter is positioned on the lens surface of a movable lens.

[0011] The apparatus includes an optical fiber and a hybrid lens positioned to receive a measurement beam from the optical fiber and generate a focal point for the measurement beam. An optical element with a surface is positioned near the focal point of the measurement beam to reflect a portion of the measurement beam back into the optical fiber as a local oscillation beam. An objective lens is positioned to receive the measurement beam from the optical element, guide a portion of the measurement beam as a probe beam to a target, and guide a portion of the probe beam returning from the target through the optical element and the imaging lens into the optical fiber to form a signal beam. In some examples, the optical element is a waveplate having an incident surface that receives the measurement beam from the imaging lens and an exit surface opposite the incident surface, wherein the exit surface is positioned near the focal point of the measurement beam to reflect a portion of the measurement beam. In other examples, the waveplate has an incident surface that receives the measurement beam from the imaging lens and an exit surface opposite the incident surface, wherein the incident surface is positioned near the focal point of the measurement beam to reflect a portion of the measurement beam. In a typical example, one of the incident and exit surfaces of the waveplate includes an anti-reflective coating positioned to receive the measurement beam from an imaging lens, and the other of the incident and exit surfaces has an uncoated portion positioned to receive the focused measurement beam from the imaging lens. In some alternatives, a polarization beam splitter is positioned to receive the measurement beam from the imaging lens and couple the measurement beam to the waveplate. In some cases, the optical element having a surface positioned near the focal point of the measurement beam is a polarization beam splitter (PBS). In other examples, the optical element comprises a PBS and a waveplate fixed to the PBS. In yet another example, the PBS has an incident surface coupled to receive the measurement beam from an optical fiber, and the waveplate includes an exit surface positioned to couple the measurement beam from the PBS to an objective lens and to partially reflect the measurement beam back into the optical fiber as a locally oscillating beam.

[0012] In some examples, the PBS is positioned to reflect a portion of the probe beam of the measurement beam onto the waveplate, and an optical detector is coupled to an optical fiber to receive a portion of the probe beam from the target and a locally oscillating beam, generating a heterodyne electrical signal. The detection system provides a target distance estimate based on the heterodyne electrical signal.

[0013] In some examples, the apparatus includes a first measurement beam source and a second measurement beam source, which respectively generate a first measurement beam and a second measurement beam at a first wavelength and a second wavelength. A beam combiner is positioned to receive the first and second measurement beam sources and couple the first and second measurement beams to form a combined measurement beam, wherein an optical fiber guides the combined measurement beam to a hybrid lens. The hybrid lens focuses the combined beam at an optical element, reflecting a portion of the combined measurement beam back towards the optical fiber as a first and second local oscillation beam. According to other examples, a first and second optical detector are coupled to be positioned to receive a portion of the probe beam from the target and the first and second local oscillation beams and generate a first and second heterodyne electrical signal. In some cases, the first and second optical detectors are coupled to an optical fiber, or coupled to receive a portion of the probe beam from an optical fiber and / or from a polarization beam splitter. The detection system provides a target distance estimate based on the first and second heterodyne electrical signals. In yet another example, the hybrid lens receives the measurement beam and the tracking beam from an optical fiber, and a dichroic filter is positioned on the axis of the objective lens, wherein the dichroic filter does not transmit the tracking beam.

[0014] The method involves guiding a tracking beam with an associated numerical aperture to a beam splitter. A portion of the tracking beam's numerical aperture is blocked, obscured, attenuated, or scattered, such that the beam splitter receives both a measurement beam and the partially obscured / attenuated tracking beam. The partially obscured tracking beam is guided from the beam splitter to a target using an objective lens, and an imaging beam is received using the beam splitter. The imaging beam is then guided to an imaging detector using the beam splitter, wherein the obscured portion of the tracking beam corresponds to the imaging detector.

[0015] The method involves focusing a measurement beam from an optical fiber to a focal point and reflecting a portion of the measurement beam toward the optical fiber to generate a locally oscillating beam. In some cases, the measurement beam is focused onto an optical element by a beam splitter having a surface that reflects a portion of the measurement beam back onto the optical fiber. In a specific example, the optical element is a waveplate, and the reflecting surface is the surface of the waveplate. In other embodiments, the optical element is a polarization beam splitter (PBS), and the reflecting surface is the surface of the PBS.

[0016] In some examples, the device includes a lidar positioned to guide a probe beam toward a target along an axis and generate an estimate of at least one target size. The lidar includes a probe beam scanner coupled to scan the axis of the probe beam. An imager is optically positioned along the axis to generate an image of the target, wherein the probe beam scanner is coupled to the imager to guide the probe beam to the target location based on at least one feature identified in the target image. In some examples, the imager is an image sensor, and an image processor identifies at least one feature in the target image. In some examples, the at least one feature is a design feature, and the target location is associated with the design feature. In other examples, the at least one feature is a processing sphere or an eyeball, and the target location is determined based on the location of the processing sphere or eyeball. In a further example, the target location is determined based on the location of the eyeball.

[0017] In a further example, the apparatus includes a lidar positioned to guide a probe beam toward a target along an axis, the lidar including a probe beam scanner coupled to scan the probe beam axis. The imaging system includes an image sensor optically positioned along an axis to generate an image of the target and a focusing mechanism coupled to an objective lens to adjust the focus of the target image at the image sensor. An image processor is coupled to the imaging system to generate an estimate of at least one target size based on the image of the target and an estimate of the distance to the target. In some examples, the lidar is configured to generate an estimate of the distance to the target, or the estimate of the distance to the target is based on adjustments to the focusing mechanism, such as an autofocus mechanism. In one example, the target location is determined based on the position of the eyeball. In some examples, the imaging system is configured to generate multiple image portions, and the image processor is configured to stitch the multiple image portions into a common image. In an additional example, the image processor is configured to at least partially compensate for distortion in at least one image portion, such as at least one image segment, based on a test grid image.

[0018] The measuring apparatus includes a lidar that provides a scanning laser probe beam and a remote mirror system including a translational mirror. The lidar is configured to guide the scanning laser probe beam to the translational mirror of the remote mirror system for reflection toward a target, thereby measuring at least one feature of the target. In some examples, the remote mirror system includes at least one machined sphere or eyeball, and the lidar is positioned to guide the scanning laser probe beam toward at least one machined sphere or eyeball to determine the position of the remote mirror system. In a typical example, the lidar is coupled to the remote mirror system to initiate an adjustment of the translational mirror such that the scanning laser probe beam is guided toward at least one feature of the target.

[0019] The foregoing and other objects, features and advantages of the disclosed technology will become more apparent from the following detailed description with continued reference to the accompanying drawings. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a representative lidar system that includes a movable lens for aiming at the image and focusing the detection beam.

[0021] Figure 2 This is a schematic diagram of a representative lidar system, including movable and fixed lenses for aiming, imaging, and focusing the detection beam.

[0022] Figure 3 This is a schematic diagram showing a representative lidar system including a dual-reflection dichroic beam splitter.

[0023] Figure 4 This is a schematic diagram illustrating a portion of a representative lidar system, including a thin beam splitter that guides a portion of the visible beam to an image sensor and guides the probe beam to and / or from an optical fiber to the probe beam.

[0024] Figure 5A The transmittance of a model optical filter designed to control the reflective portion of a tracking beam is shown.

[0025] Figure 5B The transmittance of a representative optical filter used to control the reflection portion of the tracking beam is shown.

[0026] Figures 5C to 5D Shown in the absence of ( Figure 5C ) and there are ( Figure 5D )have Figure 5B The aiming image obtained under the condition of an optical filter with the transmittance shown.

[0027] Figures 6A to 6B This is a schematic diagram of a representative optical system that includes a movable lens component and a double-reflection dichroic beam splitter.

[0028] Figure 6C Showing such as in Figures 6A to 6B The example provides the chromatic aberration of a representative optical system.

[0029] Figure 7A This is a schematic diagram of a representative optical system that includes a movable lens component and a double-reflection dichroic beam splitter.

[0030] Figure 7B An exemplary double-reflection dichroic beam splitter is shown.

[0031] Figure 8A This illustrates a lidar optical system including a peripherally weighted color filter.

[0032] Figures 8B to 8C A dichroic filter is shown that reflects the imaging beam portion to improve image quality and reduce the effective numerical aperture (NA) for imaging.

[0033] Figures 9A to 9C An optical system with a hybrid lens element having a central dichroic filter coating is shown.

[0034] Figure 9D An optical system with a hybrid lens element is shown, which has a dichroic filter coating with a transmittance-ratio-dependent angle to attenuate the central portion of the tracking beam.

[0035] Figure 9E This is a graph showing the transmittance of a representative dichroic filter as a function of wavelength.

[0036] Figures 10 to 11 The diagram shows a lidar optical system that includes a waveplate positioned as a cat's-eye retroreflector and a hybrid lens to generate a locally oscillating beam.

[0037] Figures 12A to 12B A lidar system is shown, comprising a projector optics system and a hybrid optics system coupled to communicate with a reference arm positioned in a temperature-controlled chamber.

[0038] Figure 12C A representative hybrid optics device is shown.

[0039] Figures 13A to 13C The performance of a lidar system including a cat's-eye retroreflector to generate a locally oscillating beam is shown.

[0040] Figures 14A to 14C A representative dichroic (or neutral) prism with two-fold reflection is shown.

[0041] Figure 14D A representative air gap reflector is shown.

[0042] Figures 15A to 15C This demonstrates lidar / tracker methods that can be used alone or in any combination.

[0043] Figure 16A Another example of a lidar system is shown.

[0044] Figure 16B A representative fiber optic line with two reference arms is shown.

[0045] Figure 16C This illustrates beam scanning based on the displacement of the beam transmission fiber.

[0046] Figure 17A This shows a representative multi-beam lidar.

[0047] Figures 17B to 17C A representative arrangement of fibers that generate multiple beams is shown.

[0048] Figure 17D Shown by Figures 17B to 17C The beam point at the target location is generated by the fiber arrangement.

[0049] Figure 18 This shows a representative multi-beam lidar including a detector array.

[0050] Figure 19 This demonstrates a representative method for obtaining target size and feature size using confocal lidar.

[0051] Figure 20 A representative processing and control architecture for lidar, such as confocal lidar, is shown.

[0052] Figure 21 This shows a representative tracking target defined on a sphere.

[0053] Figure 22 This illustrates a representative measurement method using confocal lidar.

[0054] Figure 23 The arrangement of the tracking target for measuring additional hidden areas is shown.

[0055] Figure 24 This demonstrates an alternative method for placing tracking targets to measure additional hidden areas.

[0056] Figures 25A to 25B This demonstrates the use of a collaborative robot (COBOT) equipped with a lidar system.

[0057] Figure 26 This demonstrates a representative method for measuring features on a target of interest.

[0058] Figure 27 A system for fast, parallel measurement of multiple target features is shown.

[0059] Figure 28 It is a block diagram of a representative manufacturing system that includes lidar or other contour measurement systems to manufacture parts and evaluate whether the manufactured parts are defective or acceptable.

[0060] Figure 29 It is a block diagram illustrating a representative manufacturing method that includes contour measurements to determine whether the manufactured structure or component is acceptable and whether one or more such manufactured structures can be repaired.

[0061] Figures 30A to 30B A representative reference arm assembly is shown.

[0062] Figure 31 This shows a representative lidar that provides focus tracking.

[0063] Figure 32 This is a block diagram of a representative method for tracking a machined ball fixed to a substrate or target (or target feature) using any of the methods and equipment disclosed herein.

[0064] Figure 33 A representative computing environment is shown. Detailed Implementation

[0065] As used in this application and in the claims, the singular forms “a / an” and “the” include the plural forms unless the context clearly indicates otherwise. Additionally, the term “comprising” means “including”. Furthermore, the term “coupled” does not necessarily exclude the presence of intermediate elements between coupled articles. In some cases, elements are referred to as directly coupled to exclude intermediate elements.

[0066] The systems, apparatuses, and methods described herein should not be construed as limiting in any way. Rather, this disclosure leads individually and in various combinations and sub-combinations to all the novel and non-obvious features and aspects of the various disclosed embodiments. The disclosed systems, methods, and apparatuses are not limited to any particular aspect or feature or combination thereof, nor are they required to possess any one or more particular advantages or problems solved. Any operational theory is provided for ease of explanation, but the disclosed systems, methods, and apparatuses are not limited to such operational theory.

[0067] Although some operations of the disclosed methods are described in a specific order for ease of presentation, it should be understood that this descriptive approach includes rearrangement unless the specific language used in the following description requires a particular order. For example, in some cases, the sequentially described operations may be rearranged or performed concurrently. Furthermore, for simplicity, the accompanying drawings may not show the various ways in which the disclosed systems, methods, and apparatus can be combined with other systems, methods, and apparatuses. Additionally, this specification sometimes uses terms such as “production” and “providing” to describe the disclosed methods. These terms are high-level abstractions of the actual operations performed. The actual operations corresponding to these terms will vary depending on the specific implementation and are readily recognizable by those skilled in the art.

[0068] For convenience, in the following description, the terms "light" and "optical radiation" refer to electromagnetic radiation propagating in the wavelength range of 300 nm to 10 μm, but other wavelengths may be used. This radiation can be directed to one or more targets to be depicted, detected, or otherwise studied. This radiation is referred to herein as propagating in one or more "beams," typically based on optical radiation produced by a laser such as a laser diode. As used in this application, the beam does not need to be collimated, and radiation propagating in a waveguide is also referred to as a beam. The beam may have a spatial distance associated with one or more lateral laser modes and can be substantially collimated. Optical fibers or other optical waveguides and coherent laser sources of readily available wavelengths are convenient. In some examples, laser diodes with wavelengths around 1550 nm are used.

[0069] For convenience, the beam is described as propagating along one or more axes. These axes are typically based on one or more line segments so that when the axis is bent or folded or otherwise responded to by mirrors, prisms, lenses, and other optical elements, the axis can include a large number of non-collinear line segments. The term "lens" as used herein refers to a single refractive optical element or a compound lens comprising one or more singlet, bilinear, or other compound lenses. In some examples, the beam is shaped or guided by refractive optical elements, but in others, reflective optical elements such as mirrors are used, or a combination of refractive and reflective elements is used. Such optical systems can be referred to as refractive, reflective, and reflective-refractive, respectively. Other types of refractive, reflective, diffractive, holographic, and other optical elements can be used, as convenient. In some examples, a beam splitter, such as a cube beam splitter, is used to split the input beam into a transmitted beam and a reflected beam. Any of these beams can be arranged, as convenient, to serve as a measurement beam or a local oscillation beam in a coherent detection system. Beam splitters can also be provided as fiber couplers, and in some embodiments, polarization beam splitters are preferred. The term "beam splitter" is also commonly used to refer to beam combiners. Fiber couplers and fiber wavelength division multiplexers (WDMs) can combine or separate beams.

[0070] In the disclosed examples, the lidar system is configured to scan a probe beam or measurement beam over a scan path that can be a polygon, a portion of a closed curve, a grating, a W-pattern, or other pattern, and the scanning can be periodic or aperiodic. In response to the measurement beam or probe beam directed to a target, a returned beam is obtained based on reflection, scattering, diffraction, refraction, or other processes at the target. Evaluation of the returned beam allows for estimation of target characteristics. Examples of lidar systems configured to provide estimates of surface topography, for example, based on a portion of the beam returned to the guiding surface of a receiver, are provided below. The disclosed methods and apparatus can also be incorporated into lidar tracker systems.

[0071] In some examples described herein, the measurement beam is divided into a probe beam directed to the target and a reference beam that can be used for calibration via a directed reference length, or as a local oscillation beam, and combined with the probe beam for heterodyne detection and target distance estimation. In other examples, the beam directed to the target is referred to as the measurement beam and the portion returned for detection is referred to as the signal beam. In the disclosed examples, portions of one or more beams are directed to a target, detector, or passed from one or more targets. As used herein, a beam portion refers to any small part of the beam, including the entire beam. In many examples, a pointing or tracking beam propagates to the target along with one or more probe beams. The tracking beam is at a visible wavelength and allows the user to confirm that the probe beam is directed to the intended target location. Otherwise, such a tracking beam is unused, and in some cases, unwanted reflections of the tracking beam can interfere with the target's aiming camera image. The wavelength of the probe beam is typically greater than about 900 nm, and the wavelength of a suitable beam source is typically around 1300 nm and 1500 nm. Other wavelengths can be used.

[0072] The disclosed systems typically include one or more beamsplitters, such as polarized beamsplitters (PBS) and dichroic beamsplitters (DBS), such as cubic or plate beamsplitters. Beam-splitting surfaces can be provided on plate surfaces, prism surfaces, lens surfaces, or other curved or planar surfaces. As used herein, a DBS is a beamsplitter that preferably reflects (or transmits) in a first wavelength range and preferably transmits (or reflects) in a second wavelength range. For ease of description, the angle (tilt angle) of the beamsplitter surface is measured relative to the optical axis from an axis perpendicular to the beamsplitter surface. While PBS and DBS allow for efficient use of the probe beam and excellent target image intensity, polarization- and wavelength-independent (neutral) beamsplitters can also be used.

[0073] In some examples, rotation is described using azimuth and elevation angles. While these angles are typically defined with reference to the longitudinal and transverse axes, as used herein, no vertical and horizontal orientation is required. Generally, these angles are used to describe the system when it is assumed to be in a reference orientation for use.

[0074] In the typical example described below, the probe beam directed to the target is polarized, but unpolarized or randomly polarized beams can be used. Optical filters are referred to as non-transmissive for transmittances of 5%, 2%, 1%, or less. Beams such as probe and tracking beams can be focused at or near the surface of interest. As used herein, a beam is said to be focused on the surface if the beam waist is within ±0.5, 1, 2, 5, or 10 Rayles of the surface.

[0075] Frequency sweep lidar

[0076] Various configurations and aspects of lidar systems are disclosed below. The disclosed systems, system components, modules, and associated methods can be used in various lidar systems. In a typical example, a so-called frequency-sweeping lidar system is provided. Typical coherent lidar systems typically use one or more laser diode light sources. The frequency of the laser diode is adjusted by adjusting the injection current of the laser diode, adjusting the temperature of the laser diode, or directly adjusting it in some other way. The laser frequency is typically adjusted using a waveform to produce a linear frequency sweep or linear "chirp". The laser frequency f(t) can then be expressed as a function of time t as follows:

[0077] f(t)=f0+(Δf / Δt)t=f0+γt,

[0078] Where f0 is the initial laser frequency, and γ = Δf / Δt is the rate of change of the laser frequency. Linear scanning is not required, and any laser frequency change as a function of time is theoretically useful, such as step or other discontinuous frequency changes or continuous changes based on polynomials or other functions; however, linear chirping is generally more convenient and practical. A frequency-modulated (FM) measurement beam is focused at the target, and a portion of the beam is scattered, reflected, refracted, or otherwise guided for collection by a receiver lens. A local oscillation beam (“LO beam”) is typically obtained as part of the same laser beam used to generate the measurement beam. The round-trip travel time associated with the measurement beam propagation to and from the target results in a frequency difference between the returning portion of the measurement beam (the return beam) and the local oscillation obtained when optically mixed. This frequency difference can be used to determine the target distance. The return beam and the LO are directed to a detector such as a PIN photodiode (commonly referred to as a square-law detector) to generate a sum-frequency signal and a difference-frequency signal. The sum frequency (in the hundreds of THz, for a 1.5 μm measurement beam) exceeds the available detector bandwidth; however, the return beam and the LO beam also generate a difference frequency Δf (heterodyne frequency) within the detector bandwidth. The distance R to the target location can be calculated as R = cΔf / 2γ, where Δf is the heterodyne frequency associated with the return beam, γ is the chirp rate, and c is the speed of light. The generation of the heterodyne frequency also requires that the LO and return beams not be orthogonally polarized; however, because the distance is determined based on the frequency difference rather than the amplitude, the polarization effect generally does not degrade the performance of the lidar.

[0079] Because the accuracy of distance measurement is limited by the frequency modulation of the laser, successful lidar systems precisely control or measure the laser frequency. For example, if the target is one meter away, a linearity of one-thousandth is necessary to ensure an accuracy of 1 mm. Therefore, the laser source used in FM lidar is configured to provide a highly linear chirp and detects and compensates for variations in linearity. In some cases, distance measurements can achieve an accuracy in the range of several micrometers.

[0080] FM lidar systems are largely unaffected by ambient lighting conditions and variations in surface reflectivity because signal detection is based on heterodyne beat frequency, which is independent of signal amplitude and unaffected by stray radiation. Therefore, variations in the amplitude or intensity of the return beam, measurement beam, or LO beam tend to have a minimal impact on distance measurements. Furthermore, coherent heterodyne detection successfully detects the limitations of optical signals on shot noise, enabling FM coherent lidar to perform reliable measurements with a return beam power as small as one picowatt, corresponding to a dynamic range of nine orders of magnitude.

[0081] In some of the examples below, systems using one or two wavelength probe beams are shown. Typically, one or more probe beams can be used, and using two anti-chirped beams allows for compensation, correction, or elimination of Doppler shift errors associated with the relative motion between the lidar and the target.

[0082] In some examples, the disclosed systems use a single objective lens (with both fixed and movable lenses) to guide and focus the probe and signal beams toward the target, producing an image of the target. This helps maintain alignment between the target image and the probe beam. Chromatic aberration correction can be challenging due to the difference in wavelengths between the probe and image beams and the high numerical aperture (NA) used, and imaging via a dichroic prism-type beam splitter can introduce significant amounts of other aberrations, such as coma. If an additional lens is used to shape the combined probe / tracking beam before focusing by the objective lens, the additional lens can be used to compensate for probe beam aberrations (such as chromatic aberration between the visible wavelength of the probe beam and the infrared wavelength of the tracking beam) independently of the imaging beam. In some cases, using such an additional lens results in excessive tracking beam reflection, and shaping the tracking beam can reduce beam portions, such as reflective portions that may interfere with target imaging. In some examples, the additional lens provides beam focus at an optical surface, such as a waveplate surface, to generate a local oscillation (LO) beam using a cat's-eye retroreflector arrangement to provide LO stability.

[0083] Representative examples of the disclosed techniques are provided below for illustrative purposes. Any feature and aspect of any example may be combined with features and aspects of other examples.

[0084] Example 1

[0085] refer to Figure 1 An optical system 100 for use with lidar or other devices includes an optical fiber 101 that emits a measuring (or probing) beam and a pointing (or tracking) beam from a fiber end 102. A beam splitter 104 is positioned to receive the probing beam and the tracking beam and guides portions of them to an objective lens 108 that includes fixed lenses 109, 112 and a movable lens 110 (shown in two positions). The movable lens 110 is typically movable along axis 120 to adjust the focus provided by the objective lens 108. The fixed lens 112 couples the combined probing / tracking beam 114 to a target 116. In a typical example, the probing beam wavelength is between 1200 nm and 1700 nm, and the tracking beam wavelength is between 400 nm and 700 nm, and typically between 650 nm and 700 nm, allowing the use of readily available laser diodes.

[0086] Objective 108 also receives a portion of the probe beam and tracking beam returning from target 116, as well as an imaging beam typically based on broadband or ambient illumination from target 116. The returning portion of the probe beam is guided through beam splitter 104 to fiber end 102 for propagation in fiber 101. The imaging beam, along with a portion of the tracking beam, is coupled to image sensor 118 by beam splitter surface 106. Beam splitter surface 106 is typically a thin-film dichroic filter, which preferably transmits the probe beam and reflects the imaging beam (or, if necessary, reflects the probe beam and transmits the imaging beam). The probe beam and tracking beam are focused onto target 116 and the imaging beam onto image sensor 118 by adjusting the position of movable lens 110 along axis 120. Therefore, objective 108 must operate over a wide wavelength range (e.g., 250 nm to 1700 nm). However, by using a single lens 108 for the probe beam, tracking beam, and imaging beam, beam alignment is maintained, and the beam does not shift during beam scanning. Figure 1 As shown, lens 108 and beam splitter 104 form projection system 130, which projects the probe beam and tracking beam onto the target and projects an image of target 116 onto image sensor 118. In some cases, image sensor 118 and fiber end 102 are optically conjugated or nearly conjugated at visible wavelengths. However, due to chromatic aberration, image sensor 118 and fiber end 102 are typically not optically conjugated at the wavelength of the probe beam without chromatic aberration correction. In some examples, such chromatic aberration can be provided and is convenient, but not required.

[0087] Example 2

[0088] Reference Figure 2A portion of a representative lidar 200 includes a projection optics system 202 arranged along axis 204, comprising an objective lens 206 having a fixed lens 210 and a movable lens 208. The movable lens 208 is translatable along axis 204 to form an image of the target at image sensor 212 and to form a probe beam and a tracking beam from fiber end 214 at the target along scannable axis 216. A beam splitter 218 (typically a dichroic beam splitter) couples the image beam to image sensor 212 and couples the probe beam and tracking beam between the target and fiber end 214.

[0089] A height reflector 220 fixed to a rod 222 scans and probes the beam. The rod is held by a bearing 224 and is rotatable about an axis 204 parallel to the z-axis of coordinate system 250. The rotation of the rod is measured using an encoder 230 positioned at the rod 216. Some components are housed within a housing 232.

[0090] Example 3

[0091] Figure 3 An optical system 300 is shown that transmits a probe beam and a tracking beam to and from a target. An optical fiber 302 with a fiber end 304 couples the probe beam and / or the tracking beam, or both, to a beam splitter 306. The beam splitter 306 includes a first prism 308 and a second prism 310, each having a dichroic (or other reflective surface) reflector 312 positioned at its respective prism facet. In some cases, the dichroic reflector 312 is defined by a thin-film coating applied to one or both of the prisms 308, 310, or by a separate coating on a separate substrate. It is convenient to fix the prisms 308, 310 to each other at the dichroic reflector 312. The dichroic reflector is positioned at an angle θ relative to a propagation axis 316. The propagation axis 316 is generally perpendicular to the prism surface 314 facing the objective lens, the prism surface 318 facing the fiber end 304, and the prism surface 320 facing the image sensor 324. As described above, the image sensor 324 and the fiber end 304 can be optically conjugated, especially at imaging / tracking wavelengths.

[0092] Dichroic reflector 312 is positioned to guide the imaging beam received from the target and objective lens to prism surface 314, such that the imaging beam is reflected (e.g., total internal reflection) to prism surface 320. Angle θ is typically chosen to provide total internal reflection at surface 314, but a coating may be provided to offer suitable reflectivity. An angle θ greater than 45 degrees reduces the angle of incidence of the beam to dichroic reflector 312, causing the dichroic reflection to exhibit less angle-dependent variation, such as the variation in reflectivity as a function of wavelength and / or the variation in reflectivity as a function of polarization state. For example, angle θ can be greater than 50°, 55°, 60°, 65°, 70°, 75°, or more, thereby reducing the angle of incidence of the beam.

[0093] Example 4

[0094] refer to Figure 4 The beam combiner / splitter optical system 400 includes an optical fiber 401 with a fiber end 402, which delivers a tracking beam and / or a probe beam to a plate beam splitter 406. The probe and / or tracking beam is coupled (in this example, delivered) by the plate beam splitter 406 along axis 416 to the objective lens. The imaging beam returning from the objective lens is coupled by the plate beam splitter 406 through a narrowband filter 408 and focused at the image sensor 410. In this example, the plate beam splitter 406 is a dichroic beam splitter, such that the probe beam is effectively coupled to the target and the imaging beam is effectively coupled to the image sensor 410. The narrowband filter 408 attenuates at the wavelength of the tracking beam. Figure 5A The model transmission curve of this filter is shown in the figure; Figure 5B The figure shows a representative transmission curve 500 of the manufactured example dichroic filter; and Figures 5C to 5D These are representative images obtained with and without this filter, respectively.

[0095] have Figure 5B The dichroic filter (beam splitter) with the characteristics shown can be positioned, for example, on prism surface 320 (see...). Figure 3 Typically, a suitable filter is positioned closest to the image sensor (e.g., [image sensor]). Figure 3 The image sensor 324) is located at the prism surface and is provided as a coating on the selected prism surface. The dichroic filter can function as a bandpass optical filter with a transmission bandwidth of 480 to 630 nm in the range 504, wherein the average transmittance at an incident angle of 0 degrees is greater than or equal to 90%. The dichroic filter also functions as a notch filter in the wavelength range of 652 nm to 662 nm, wherein the transmittance is 5% ± 3%, as noted at 506. Longer wavelengths are not used, and the performance of the dichroic filter at these wavelengths is irrelevant. Figure 5B Example than Figure 5A The model is easier to manufacture. Generally, it is preferred that the transmittance of the image sensor imaging is greater than 50%, 75%, 80%, or 90% in the range of about 480 nm to 630 nm, while the transmittance at the tracking wavelength is less than 10%, 5%, 2.5%, 1%, or 0.5%.

[0096] Example 5

[0097] refer to Figure 6AA representative lidar system 600 includes an objective lens 602 having a fixed lens 604 positioned along axis 608 and a movable (focusing) lens 606. The focusing lens 606 is typically fixed to a stage movable along axis 608. (The focusing lens 606 is shown in dashed lines at the second focal position). A fiber end 610 couples the probe beam and / or tracking beam to a hybrid optics device 609 including a polarizing beam splitter 612, a hybrid lens 614, and a quarter-wave plate 616. As discussed further below, the hybrid lens 614 focuses the probe beam onto surface 617 of the wave plate 616 such that a reflected portion of the probe beam returns toward the fiber end 610 to serve as a local oscillation beam. The combined probe / tracking beam is focused at the target by the objective lens 602 through a double-reflection beam splitter 618 having surfaces 620, 622, and 626 perpendicular to axis 608. The dichroic surface 623 (or other beam-splitting surface) guides the imaging beam from the target to the image sensor 630 and transmits the return portion of the probe beam from the target to or toward the fiber end 610. To reduce the portion of the tracking beam reaching the image sensor 630, a suitable narrowband filter 629 can be provided, such as... Figures 5A to 5B As shown. A notch filter or other filter can be used to reduce any additional portion of the tracking beam that may reach the image sensor 630. Passing twice through the quarter-wave plate 616 causes a portion of the returned probe beam and the probe beam reflected at surface 617 (forming the LO beam) to be in a common linear polarization orthogonal to the polarization of the probe beam emitted from fiber end 610. The returned probe beam and the LO beam then interfere at detector 611 for null or heterodyne detection. Figure 6A As shown, the PBS 612 is positioned to transmit the probe beam from the fiber end 610 and reflect the returned signal and LO beams, but the PBS 612 can be arranged to reflect the probe beam and transmit the returned probe and LO beams. As mentioned above, the dichroic surface 623 is tilted to allow for improved dichroic coating performance because it can be designed for smaller incident angles, i.e., less than 45 degrees, which is typical for cubic beam splitters. Additionally, the variation in reflectivity as a function of defocus is reduced, and the target image position tends to shift without responding to defocus. While the prism surface is conveniently perpendicular to axis 608, other angles can be used. The dual-reflection beam splitter 618 also provides an additional gap 650.

[0098] Example 6

[0099] exist Figure 6BIn another example shown, one or more probe beams are emitted by fiber 652 and guided to the target via PBS 654, probe beam lens or lens assembly 656, quarter-wave plate 657, double-reflection prism 658, movable lens 660, and fixed lens 662. A portion of the probe beam returns to detector or detector assembly 670, and the observation beam is coupled to image sensor 672 via double-reflection prism 658. The LO beam is also guided to detector 670 by PBS 654. In other examples, the LO beam is generated by reflection from the surface of waveplate 657.

[0100] To acquire high-quality images at image sensor 672, chromatic aberration at visible wavelengths must be minimized. However, achieving acceptablely low chromatic aberration values ​​at visible wavelengths, as well as between detection (IR) and pointing (red laser), presents a demanding challenge for lens design. Figure 6C The diagram illustrates chromatic aberration at the visible wavelength (within range 690, chromatic aberration is indicated by arrow 691), the detection (i.e., IR) wavelength indicated at 695, and the pointing beam wavelength at 694. A hybrid lens 656 is selected to reduce or eliminate chromatic aberration between the pointing beam and the detection beam (visible and IR), and lenses 660 and 662 are selected to reduce chromatic aberration within the visible light range 690. Focus shift is shown for target distances ranging from 0.5 m to infinity; the curves almost overlap except for curve 697 associated with a 0.5 m target distance.

[0101] Example 7

[0102] Figure 7A An optical assembly 700 is shown, including an objective lens 702 that transmits one or both of a probe beam and a tracking beam toward and from a target, and receives imaging light (referred to in some cases as an imaging beam) from the target. The objective lens 702 includes a fixed lens 704 and a movable lens 706 that allows the probe beam and tracking beam to be focused onto the target and imaged onto an image sensor 708. A beam splitter 710 transmits the probe beam and tracking beam to the target via the objective lens 702 and transmits at least a return portion of the probe transmission from the target for coupling to one or more detectors. Figure 7A (Not shown in the image). Beam splitter 710 includes optical surfaces 712, 714, 716 positioned perpendicular to the propagation axis 718 (optical surface 714 is perpendicular to the propagation axis, as if folded at 716, 720). The propagation axis 718 is defined by axial segments at various angles relative to each other. Beam splitter 710 includes a first prism 710A, a second prism 710B, and a beam splitter layer 720, which is typically a multilayer thin-film coating providing wavelength-dependent reflection and transmission. The imaging beam used to form an image of the target is... Figure 7AThe prism, denoted as 722, is reflected by the beam splitter layer 720 and then by the optical surface 716 to the image sensor 708. The prism angle β is typically chosen such that the imaging beam is incident at an angle greater than the critical angle, i.e., greater than sin(θ). 1 (1 / n), where n is the refractive index of prism 710B. In some examples, the probe beam (or multiple probe beams) has an intermediate focus at plane 740, for example, at the surface of the waveplate as described above.

[0103] refer to Figure 7B The optical system used for beam combining and separating includes a beam splitter 752, which is similar to... Figure 7A The beam splitter 710, however, has a dichroic surface 754 that reflects one or more probe beams (and portions of the tracking beam) from the source / detector system 760 to the target and couples the return portions of one or more probe beams to the source / detector system 760. The image beam is transmitted to the image sensor 764 along axis 762. As in other examples, axis 762 is defined by axis segments at various angles relative to each other, and portions of axis 762 extend into the source / detector system 760 and the image sensor 764.

[0104] Example 8

[0105] refer to Figure 8A The optical system 800 includes a fiber end 802 positioned to couple a probe beam and / or a tracking beam to a beam splitter 804. The objective lens 806 includes a fixed lens 810 and a movable (focusing) lens 808 to focus the probe beam onto a target. An optical filter 820 is positioned to receive the probe beam and the tracking beam, and to at least transmit the probe beam to the target. The filter 820 includes a dichroic layer 822 having an aperture 824. The dichroic layer 822 is typically annular and is selected to be transmissive at the probe beam wavelength and attenuated at the visible wavelength or other wavelengths used by the image sensor 830. Therefore, the filter 820 reduces the numerical aperture of the imaging beam, which simplifies the design of the objective lens 806. It will be understood that designing a lens suitable for both accurate imaging and beam focusing in the wavelength range of 400 nm to 700 nm (for target imaging) and 1300 nm to 1600 nm (for probe beam focusing) can be challenging. By using filters such as filter 820, the numerical aperture of the probe beam can be kept large to allow for fine focusing, while limiting the numerical aperture of the imaging beam to provide a satisfactory image. Although Figure 8A The image shows a dichroic layer 822, but a similar absorption layer can be used. The diameter or other dimensions of the aperture 824 can be selected in conjunction with the objective lens design. Figure 8AIn the example, the difference in optical path length between propagating through aperture 824 and propagating through dichroic layer 822 is typically kept small enough to avoid introducing focus error into the probe beam.

[0106] Figures 8B to 8C Representative filters 850 and 860 are shown. Filter 850 includes an attenuation ring 852 and a transmission center region 854 disposed on one, any one, or both surfaces of a substrate. The attenuation ring 852 may be provided with absorption, reflection, polarization, or other layers, which preferably attenuate the imaging beam (typically between 400 nm and 700 nm, but other wavelengths can also be used for imaging). The attenuation ring 852 and the transmission center region 854 may have a common thickness or a common optical thickness to eliminate or reduce the probe beam focus error associated with the phase difference between the attenuation ring 852 and the transmission center region 854. Figure 8C In the example, filter 860 includes an attenuation ring 862 positioned around transmission region 864.

[0107] Example 9

[0108] Figure 9A An optical system 900 is shown, including a fiber end 902 positioned to guide one or more probe and tracking beams to a polarization beam splitter (PBS) 904 and an imaging lens 906. The imaging lens 906 focuses the probe beam onto a surface 908 of a waveplate 910, which is typically a quarter-waveplate that produces a circularly polarized state (SOP) in the probe beam. Typically, the imaging lens 906 forms an image of the fiber end 902 on the surface 908 of the waveplate 910. The surface 908 partially reflects the probe beam back to the imaging lens 906 so that it returns to the fiber end 902 or is otherwise guided, typically as a local oscillation beam. The surface 908 can be an uncoated surface, as a few percent reflectivity is generally sufficient to produce adequate local oscillation beam power. By positioning the surface 908 at the focal point of the imaging lens 906, the local oscillation beam tends to return to the fiber end 902, exhibiting a decreasing variation in response to the tilt of the waveplate 908. Dichroic beam splitter 912 receives the probe beam and the tracking beam, and objective lens 914 focuses the probe beam onto target 916. A portion of the returned probe beam is coupled back to fiber end 902, and the imaging beam is reflected by beam splitter 912 to image sensor 920.

[0109] like Figures 9A to 9BAs shown, the imaging lens 906 also includes a central shield 922, which is positioned to block the central portion of one or more probe or tracking beams. In most examples, a portion of the tracking beam is blocked or attenuated within a selected angular diameter, such that all or part of the tracking beam reflected by the target-facing surface 926 of the beam splitter 912 does not reach the image sensor 920. This blocking reduces the portion of the tracking beam reaching the image sensor, resulting in a superior target image. Beam portions 930, 931 (i.e., the portion of the beam at the larger numerical aperture) propagating from axis 936 toward the target 916 are reflected by the beam splitter 912 but do not reach the image sensor 920. The central portion 932 of the tracking beam (the lower numerical aperture portion) is blocked or attenuated and does not reach the image sensor 920 or reaches it with reduced beam power. The central shield 922 is typically provided by a dichroic reflector that transmits the probe beam and reflects the wavelength of the tracking beam. The size of the dichroic reflector is based on the corresponding size of the image sensor. In some examples, the imaging lens 906 focuses the probe beam within the beam angular diameter α, and the size of the dichroic reflector is at least 0.5, 0.75, 1.0, or 1.5 times the product of the corresponding size of the image sensor and the ratio of the optical distance along the axis from the focal point of the mixing lens to the optical distance from the focal point of the mixing lens to the image sensor. Figure 9C As shown, the attenuation of the occlusion size d of the tracking beam portion reflected to the image sensor 920 obs It can be determined as d obs =(Z SENSOR / Z MIXLENS Z)D, where D is the image sensor size, Z SENSOR and Z MIXLENS This is the axial distance between the image sensor 920 and the center mask 922 and the focal point of the hybrid lens. Depending on the desired degree of exclusion of the tracking beam portion, larger or smaller dimensions can be used. (For convenience, Figure 9C Showing the unfolded Figure 9A (optical system)

[0110] Figure 9D This illustrates another method to reduce the portion of the tracking beam reaching the image sensor. Similar to... Figure 9AIn the optical system, an imaging lens 952 creates a focal point for the probe beam at a surface 958 of a waveplate 960 or other optical element. A dichroic coating 956 is provided at the imaging lens 952, providing variable transmission as a function of the incident angle and wavelength. Typically, the central portion of the dichroic coating 956 is highly reflective to the tracking beam but transmissive to the probe beam. Other portions of the dichroic reflector, such as those associated with higher incident angles, tend to transmit both the tracking and probe beams. This coating can be placed on other surfaces, such as the planar surface of a beam splitter or waveplate. Figure 9E This is the transmission curve of a representative dichroic coating. For example... Figure 9E As shown, the probe beam is transmitted at an incident angle of up to 30 degrees, while the transmission of the tracking wavelength changes significantly, exhibiting low transmission at vertical incidence and increasing transmission as a function of angle.

[0111] Example 10

[0112] refer to Figure 10 The optical system 1000 includes an objective lens 1002 and a hybrid optical system 1004 that guides a probe beam and a tracking beam to the objective lens 1002 for focusing onto a target 1008. In some cases, two anti-chirped probe beams are used. The hybrid optical system 1004 includes a fiber end 1010 that guides one or more probe beams and tracking beams as a combined beam 1013 to a PBS 1012, and then to a hybrid lens 1014. The hybrid lens 1014 focuses the combined beam 1013 onto a surface 1018 of a waveplate 1016, and the reflected portion of the probe beam from surface 1018 returns toward the fiber end 1010 to serve as a local oscillation beam. The polarization state (SOP) of the reflected portion from surface 1018 is rotated by 90 degrees. The opposite side of the waveplate 1016 typically has an anti-reflective coating.

[0113] The combination of hybrid lens 1014 and waveplate 1016 serves as cat's-eye retroreflector 1030, which tends to be insensitive to the tilt of waveplate 1016. One or more probe beams and portions of one or more local oscillator beams are guided by PBS 1012 to detector assembly 1032, which typically includes respective detectors coupled to receive the probe beam portion and LO portion for each probe beam wavelength.

[0114] Example 11

[0115] Figure 11 Showing with Figure 10In a similar optical system, the probe / tracking beam is reflected by the PBS 1112 to a hybrid lens 1114 to focus the probe / tracking beam onto the target-side surface 1118 of the waveplate 1116, thereby rotating the polarization state (SOP) of the reflected portion from surface 1118 by 90 degrees. The opposite side of the waveplate 1116 has an anti-reflective coating 1121. In this example, the returned beam portion is transmitted to the detector 1132 by the beam splitter 1112.

[0116] Example 12

[0117] refer to Figure 12A The lidar system 1200 includes a pointing laser 1202, a first probe laser 1204, and a second probe laser 1206 coupled to a fiber module 1210. The fiber module includes a temperature-controlled, evacuated, or inert gas-filled hermetically sealed container 1211. The probe lasers 1204 and 1206 are coupled via respective optical isolators 1205 and 1207, and then coupled to a wavelength division multiplexer (WDM) 1212, which combines the first and second probe beams for output to the fiber module 1210. The fiber module 1210 includes a fiber coupler 1214 that directs a portion of the combined probe beam to the WDM 1216, which combines a portion of the probe beam with a tracking or pointing beam (such as a red or other visible beam) from the tracking laser 1202, and outputs the combined probe / pointing beam at fiber end 1218. In other examples, WDM 1212 and fiber coupler 1214 are replaced by a single coupler positioned within a sealed container 1211. Coupler 1214 also guides a portion of the probe beam to coupler 1222, which in turn couples the beam portion to coupler 1224 via two different paths, one of which contains reference fiber 1226. Coupler 1224 then combines the beam portions associated with the different paths and guides the combined beam to WDM 1228, which directs the beam portion from each path to reference detectors 1230, 1232, respectively, associated with the wavelengths of the first probe laser 1202 and the second probe laser 1204. The beam portions at each reference detector 1230, 1232 generate heterodyne signals with frequencies associated with the length of reference fiber 1226 and the frequency chirps in the first and second probe beams. Based on these heterodyne signals and the known length of reference fiber 1226, the probe laser frequency chirps and the resulting measurement signals from target 1250 can be used for calibration or validation of distance measurements.

[0118] Fiber end 1218 couples the combined beam to hybrid optics 1234. PBS 1236 receives the combined beam, and hybrid lens 1238 forms the beam focus at surface 1240 of quarter-wave plate 1239, which reflects the local oscillation portion back to PBS 1236. The remaining portion of the combined beam is directed to projection optics 1242, where the beam is propagated through beam splitter 1244 (shown as a plate, but could be a cube, double reflector, or other) to an objective lens having a fixed lens 1248 and a movable lens 1246 for focusing the combined beam onto target 1250. The beam splitter directs the imaging beam to camera 1257. One or more scanning mirrors 1249 (typically as...) Figure 2 The combined beam (as shown) is directed to target 1250, and the return portion of the combined beam from target 1250 is directed back to projection optics 1242 and hybrid optics 1234. The beam portions returning from target 1250, along with their respective local oscillator beams, are reflected by PBS 1236 to dichroic beam splitter 1260. Detectors 1262 and 1264 are positioned to receive the beam portions and local oscillator beams associated with their respective wavelengths and generate the corresponding heterodyne signals. In other examples, a conventional beam splitter (i.e., unpolarized and non-dichroic) is used in front of each detector along with a wavelength filter. This configuration typically involves some additional signal loss but can be more conveniently produced.

[0119] like Figure 12A As shown, a local oscillation (LO) beam is generated using reflections from the surface of a quarter-wave plate at the focal point of the hybrid lens. The combined lens 1238 and quarter-wave plate 1239 serve as a cat's-eye retroreflector for the incident beam focused onto the surface of the quarter-wave plate 1239. Even when the quarter-wave plate 1239 is tilted, it provides alignment of the LO and the returning portion of the probe beam. For example, for a hybrid lens focal length of 7.5 mm, at... Figure 13A The diagram shows the beam offset (spot offset) as a function of waveplate tilt for displacements between -0.6 mm and 0.6 mm from precise focusing. For precise focusing, the spot offset is zero for all tilts. Figure 13B The signal loss is shown as a function of point offset. Figure 13C The point offset (SO) at the detector surface between beams 1302 and 1304 is shown.

[0120] Figure 12B Showing with Figure 12A The LiDAR 1200 is similar to the LiDAR 1280. However, in Figure 12BThe example illustrates a temperature-controlled furnace 1290 containing some or all components of a reference path, such as fiber 1226. Typically, it is preferable to position all fiber optic elements within the furnace, evacuate, and hermetically seal the furnace. Fiber end 1218 guides the combined beam to a local oscillating optics assembly 1291, which includes a PBS 1292 that guides a portion of the probe beam to a detector assembly 1293. It should be noted that the reflected portion is only a small fraction of the total beam because the PBS is not perfect, thus reflecting some "incorrect" polarization. The remaining portion of the probe beam is guided to a quarter-wave plate 1294, and the portion returning from the target is reflected by the PBS 1292 back to the quarter-wave plate 1294, then reaches a retroreflector 1295. The probe beam is then guided to the detector assembly 1293, as shown. Instead... Figure 12A Plate-shaped beam splitter 1244 and cube beam splitter 1296 are positioned to reflect portions of the viewing beam to camera 1297. Lens 1238 allows for independent focusing of the probe beam and the imaging beam using lenses 1246 and 1248.

[0121] Figure 12C A hybrid optics device 1279 is shown, comprising a cat's-eye assembly 1284 and a detector module 1281. The cat's-eye assembly 1284 includes a lens 1285 that focuses an input probe beam onto the surface of a waveplate 1286 to generate an LO beam by reflection. The detector module 1281 includes a PBS 1283 that directs portions of the LO and returned probe beam to a dichroic beam splitter 1287, such that a transmitted portion of a first wavelength is directed to a detector 1288, and a reflected portion of a second wavelength is directed to a detector 1289. The wavelength difference between the first and second wavelengths can be 1, 2, 5, 10, 20, 50, or 100 nm or greater, for separation by the dichroic beam splitter 1287. The hybrid optics device 1279 can be compact (total volume less than 2 cubic inches), requires few components, and can be easily and stably aligned.

[0122] Example 13

[0123] Figures 14A to 14D This involves a double-reflection beam splitter. Figure 14A A dual-reflection prism beam splitter 1400 is shown, wherein the dichroic surface 1404 is positioned at an angle β, which is defined as the apex angle of the prism 1406. Figure 14B This is a detailed view of prism 1406, showing the prism angles relative to axis 1408 perpendicular to beam splitter surfaces 1410, 1412, as well as the incident and reflection angles. Figure 14C Another alternative dual-reflection beam splitter 1420 is shown, which may include prisms, such as prism 1406. Figure 14DAs shown, the dual-reflection beam splitter 1452 includes a plate-shaped dichroic beam splitter 1454 and a reflector 1460. The plate-shaped dichroic beam splitter 1454 and the reflector 1460 are positioned on an axis 1456. For example, the reflector 1460 may be defined on the surface 1458 of a transmission plate.

[0124] Example 14

[0125] Figures 15A to 15C Representative methods are shown, either alone or in combination, in lidar or laser tracker systems or other optical measurement systems. For example... Figure 15A As shown, method 1500 includes combining a probe and a tracking beam at 1502, and guiding the combined beam to a target at 1504 using an objective lens having a fixed portion and a movable portion. A portion of the probe beam received from the target is returned to a dichroic beam splitter and guided to a detector at 1506. At 1508, an imaging beam is guided to an image sensor, and at 1510, the focus of the probe beam at the target and the focus of the imaging beam at the image sensor are adjusted using a movable lens.

[0126] like Figure 15B As shown, method 1530 includes combining one or more probe beams and tracking beams at 1532, and focusing the combined beam onto a reflective surface at 1534 to generate a backpropagating local oscillation (LO) beam including a portion of each probe beam. At 1536, a portion of the probe beam received from the target is received and guided along with one or more LO beams to one or more detectors. At 1538, the target distance or height is estimated based on the heterodyne frequency between the returned probe beam portion and the corresponding LO beam.

[0127] like Figure 15C As shown, method 1550 includes combining beams (e.g., one or more probe beams and a tracking beam) at 1552 using a beam splitter (such as fiber-based WDM), and blocking the central or low-NA portion of the tracking beam at 1554. At 1556, the combined beam (smaller than the central portion of the tracking beam) is directed to a dichroic beam splitter. At 1558, the imaging beam is directed from the dichroic beam splitter to an image sensor, and at 1560, the return portions of one or more probe beams are processed to generate a distance or height estimate. Typically, the return beam portion is mixed with a corresponding local oscillator beam to generate an electrical signal at the heterodyne frequency, and the heterodyne frequency is calibrated relative to distance / height.

[0128] Example 15

[0129] Figure 16AA representative lidar 1600 is shown, comprising a fiber optic module 1602 positioned within a typically temperature-controlled, hermetically sealed inert gas-filled or evacuated housing 1603. The fiber optic module 1602 includes an optical isolator 1606 and a fiber coupler 1608 coupled to a probe laser 1604. A WDM 1610 is coupled to receive a portion of a probe beam from the probe laser 1604 and a portion of a tracking beam from a tracking laser 1612, and couples the combined probe / tracking beam to a hybrid optics 1614. The hybrid optics 1614 couples a portion of the probe beam returning from the target to one or more detectors 1616 to generate an electrical signal that is processed to determine the target's distance or altitude. The hybrid optics 1614 couples the combined probe / tracking beam to a projection optics 1618, and then to a beam scanner 1620 for delivery to the target. The projection optics 1618 also guides the imaging beam to an image sensor, which, in combination with an objective lens provided in the projection optics 1618, functions as a boresight camera 1617. The beam scanner 1620, projection optics 1618, and hybrid optics 1614 also guide a portion of the probe beam returning from the target to one or more detectors 1616. Furthermore, a reference photodiode 1630 is coupled to fiber couplers 1632, 1634, such that a portion of the probe beam received from coupler 1608 is guided to a reference fiber 1636 of a predetermined length, allowing the heterodyne signal frequency to be correlated with distance or altitude. The lidar 1600 can use any of the hybrid optics, projection optics, and beam scanners disclosed herein, and in some cases, one or more may be omitted. In one variation, detector 1616 is omitted, and detector 1622 is coupled to fiber coupler 1624 of fiber module 1602 to receive the signal beam.

[0130] Figure 16A The example shows only a single probe laser, but typically two probe lasers of different wavelengths are used, and these lasers produce an anti-chirped beam that allows heterodyne detection, reducing or eliminating the Doppler shift associated with target motion. As in most examples, the tracking beam is used to confirm alignment, but it is not used for other purposes.

[0131] Example 16

[0132] refer to Figure 16BA representative optical system 1650 includes a first probe laser 1654, a second probe laser 1658, and a visible (typically red-emitting) laser 1652. A portion of each probe laser beam is directed to its respective reference paths 1666, 1668 to generate a heterodyne signal at its respective detectors 1656, 1658. A coupler 1670 combines portions of the probe beams and then combines them with a visible beam from the visible laser 1652 at a visible / probe coupler 1672. Typically, a hermetically sealed temperature controller housing 1664 is provided to stabilize the reference heterodyne frequency.

[0133] Example 17

[0134] Figure 16C Alternative optical system 1680 is shown. Actuator 1690 is attached to the output fiber end 1688, thereby allowing displacement of the fiber end 1688 and the associated output beam. Voice coils, piezoelectric devices, or other devices can be used as actuators. As described above, the displaced beam is guided through beam coupler 1684 and hybrid optics 1682 to lens 1691, which images the output beam onto the target. Beam displacement results in a small motion or scan of the output beam at the target. For relatively small fiber motion, the LO beam generated by the hybrid optics and the measurement beam remain efficiently overlapped at detector 1686 to provide a usable RF (heterodyne) signal. By using small, fast actuators, such as voice coils or piezoelectric stacks, the beam can be scanned very quickly and accurately. Dual actuators can be used to scan in two lateral directions. This provides a method for measuring carefully selected points on a target to quickly measure features such as holes or pillars without using scanning mirrors, which are typically much slower. To accommodate the beam displacement associated with this scan, a larger detector area may be convenient; however, an excessively large detector size can limit detector bandwidth and reduce the heterodyne signal amplitude. In one example, a 1 mm fiber displacement produces an angular beam scan of 0.4 mrad. Although in Figure 16C Only a single probe beam of a single wavelength is shown, but two or more wavelengths can be used with the corresponding detector.

[0135] Example 18

[0136] like Figures 17A to 17CAs shown, the measurement system 1700 may include multiple fiber outputs 1701 to provide multiple measurement positions that can be measured simultaneously. The measurement system 1700 includes a visible laser 1702 and a probe laser 1704 coupled via an optical isolator 1705. A portion of the probe laser beam is guided by a reference arm tap (typically a fiber coupler) 1706 to a reference arm 1712 and a visible / probe coupler 1703. A 1×N coupler 1708 receives the combined visible / probe beams and generates N combined visible / probe output beams. Alternatively, a 1×N switch can be used. These N beams can be guided to a shared scanning and projection optics. For illustrative purposes, the associated local oscillation beams and detectors are not shown.

[0137] Figures 17B to 17C A representative array 1720 is shown, configured to guide N beams into a hybrid optics device. Representative fiber ends 1722 to 1726 are arranged in a cross shape, each fiber end having a corresponding core, such as core 1727. If the output fibers are standard 125 μm diameter PM fibers, then the cores are spaced 125 μm apart if the fibers are in contact. Focusing this array onto a target produces... Figure 17D The beam pattern 1750 shown has beam points 1753 and 1756 indicated as pointing directly at a visible target surface, while beam point 1752 is within a recess 1706 in the target. The angular spacing of the combined beams can be 0.5, 1, 2, 5, 10, or 20 mrad or greater. Larger spacing may require attention to objective lens characteristics to maintain a proper beam focus, and large beam spacings (such as 0.5, 1, 2, 5, 10, 20 mm) can be achieved. Figure 17D In the example, beam points 1753 to 1756 surrounding aperture 1706 will simultaneously provide a return probe beam associated with the distance to the plane of aperture 1706, and the image of recess 1706 can be processed to provide the aperture diameter along with the distance information. This measurement will be much faster than conventional methods that require scanning.

[0138] Figure 18A representative multi-fiber optical configuration is shown. In this configuration, detector array 1810 is positioned to capture the mixed signal from each fiber (i.e., the returned probe beam portion and the LO beam). Multiple fiber ends 1802 (including representative fiber ends 18021, 18022) guide the probe beam to a polarization beamsplitter and a cat's-eye assembly 1807, which includes a lens and a quarter-wave plate as described above. The cat's-eye assembly 1807 generates the LO beam by reflecting a portion of the probe beam from the surface of the quarter-wave plate. The probe beam is guided by objective lens 1811 to object 1812; the probe beam from each fiber of the multiple fiber ends 1802 provides a corresponding beam point at object 1812 (e.g., representative beam points 18081, 18082). A portion of the probe beam from object 1812 returns to objective lens 1811, cat's-eye assembly 1807, and the polarization beamsplitter (PBS), and then to the corresponding detectors of detector array 1810 (e.g., representative detectors 18101, 18102). If a dual-wavelength probe beam is used, a dichroic beam splitter and an additional detector array can be employed. Only beams from the two fiber ends are shown: beams from fiber end 18021 are indicated as 18041 and 18061, and beams from fiber end 18022 are indicated as 18042 and 18062. The heterodyne signal associated with each of the plurality of fiber ends 1802 is processed at a corresponding processing element 1820 (such as processing elements 18201, 18202) to establish a distance, range, or size estimate. In other examples, a single processing system is used, and the heterodyne signals are processed one at a time. For example, an electrical switch can receive all heterodyne signals and sequentially couple selected heterodyne signals for processing. Figure 18 The diagram shows the fiber ends distributed in a single direction, but a cross shape or other distribution can be used (e.g., along a diagonal, a curve, the edge of a polygon, and / or inside).

[0139] Example 19

[0140] LiDAR can include a camera aligned along the radar axis. Such an implementation can use an inexpensive surveillance camera with calibration parameters that vary with spatial orientation relative to gravity and environmental conditions such as temperature. Camera data is processed and presented independently of laser scan data, and real-time coordination between camera and LiDAR data can be challenging. In some published examples, the metrology camera is positioned using a common-focus optics with a LiDAR measurement path; this camera is referred to herein as a confocal camera, and the associated LiDAR as a confocal LiDAR (cLR). This provides measurements in six degrees of freedom (DOF) between the camera and LiDAR. This camera can be a high-resolution camera and is coupled to provide camera data at a low level in the system architecture to minimize or reduce latency between data, thereby allowing real-time coordination between LR and camera data. Using two measurement modes (LR and camera) in the confocal LiDAR allows the LR to be pointed to optimally measure the features of interest. Additionally, the low latency data interface allows for real-time algorithms and tracking of features identifiable in the camera.

[0141] LiDAR measures azimuth, elevation, and distance to the surface of interest. Azimuth and elevation are read from encoders on the appropriate axes. Distance measurement is performed using heterodyne interferometry and can be conducted on almost any surface without interference from ambient light. The conversion from distance (R), azimuth (A), and elevation (E) to linear coordinates (XYZ) is performed using well-known spherical to Cartesian coordinates, such as:

[0142] X LR =R*cos(E)*cos(A)

[0143] Y LR =R*cos(E)*sin(A)

[0144] Z LR =R*sin(E)

[0145] A calibrated camera can be viewed as an angle measurement device, where the azimuth and elevation angles of each pixel in an image can be determined. Utilizing the confocal relationship between the LR and the camera, distance measurements can provide a scale to the camera image. This relationship allows the camera's center pixel to be aligned with the XYZ coordinates. LR Directly related. While it cannot be guaranteed that the projection of the camera's focal plane onto the scene will be perpendicular to the central axis of |LR|, the actual relationship can be determined through a calibration process. Using a calibrated camera, once the distance is determined by LR, planar features can be measured directly by the camera. Once the distance is established, other features with known geometries such as spheres can also be measured.

[0146] See again Figure 12AAn autofocus (AF) linear translation stage 1253 is coupled to one or more lenses among lenses 1246, 1248 to allow the probe beam to be focused at a measurement distance (e.g., 0.5 m to 30 m or 50 m). A beam splitter 1244 reflects visible light (or other imaging radiation) from the target or other scene to camera 1257, allowing the beam position to be displayed on a camera screen or other display device. Camera 1257 is coupled to one or more processing systems 1258, and its output can also be used to provide an input image for computer-based measurement algorithms. Because camera 1257 and the probe beam share the same focusing optics, the relationship between the camera sensor array and the position of the measurement beam on the target (measurement point) remains invariant as long as the camera mount is stable. This invariance establishes camera 1257 as a confocal camera and allows for scanning beam focusing using the autofocus stage 1253. In one example, the focus is adjusted to provide maximum contrast in the image produced by camera 1257. In this arrangement, the probe beam can be quickly focused and guided to a selected position in the camera image. If present, calibration can be used to correct for positional variations of the probe beam relative to the camera at different focal positions, such as any variations due to ambient temperature. Additional focus correction can be performed using the focus signal of the LiDAR probe beam provided by the LiDAR focus controller 1255. In other examples discussed below, the processing system 1258 can be used to stitch images together to form a larger image, correct distortions in the images to be stitched together, and identify or track target features or objects such as a processing ball or an eyeball.

[0147] Example 20

[0148] refer to Figure 19 The method for establishing the size or dimensions of a target feature 1900 includes establishing the distance to the target surface at 1902. If the target surface is planar, as determined at 1903, an image of the target feature is obtained at 1904. If the target surface is not planar, the target surface shape, tilt, and distance are typically established at 1905 through additional scans. Alternatively, distortions in a preliminary image of the shape or structure of a known geometry can be evaluated. At 1906, the image magnification is determined for some or all image (i.e., target) locations. At 1910, using the determined image magnification, the feature size on the image can be appropriately scaled to the actual size. At 1910, these scaled dimensions can be reported or stored. In some examples, the scaled dimensions are compared to the design dimensions to determine if the feature has been correctly sized.

[0149] Example 21

[0150] refer to Figure 20The lidar system 2000 includes a lidar ranging system 2002, which includes reporting and adjustment for establishing the target azimuth and elevation angles, lidar ranging measurement electronics for reporting distance, and motors for controlling the azimuth and elevation angles. A confocal camera 2004 is also positioned to generate an image of the target, and both the lidar ranging system 2002 and the camera 2004 are coupled to an embedded processor 2006. Therefore, lidar distance data and image data are provided to the embedded processor 2006 without the increased latency associated with communication of such data to a remote processor via a network or other communication connection (such as Ethernet or Universal Serial Bus (USB)). Figure 20 The example system allows for the collaborative use of confocal camera and LiDAR data, achieving rapid operation through tight coupling of the LiDAR ranging system and the confocal camera. Each of these measurement systems continuously creates a data stream. As shown, this data is combined at an embedded computer physically associated with the confocal LiDAR. This use of an embedded computer with confocal LiDAR facilitates searching where selected features are measured based on computer-aided design (CAD) measurements, which are digital representations of the part to be measured. In many cases, there exists a list of features to be measured in CAD coordinates. Under normal circumstances, when measuring the actual part, the features are not on the ideal coordinates of the CAD. Furthermore, the ideal measurement is preferably performed with the measuring device, in this case, the confocal LiDAR, centered on the feature to be measured. Search algorithms capable of identifying any pre-selected features must be implemented, but these algorithms can be very inefficient. Due to the confocal and / or metrological relationship of the confocal LiDAR, features of interest can be automatically and quickly centered when they are within the camera's field of view.

[0151] In other examples, rapid alignment can be achieved before measurement. In many applications, alignment with the part must be performed before the system measures the features of interest. Alignment can be of two types: (1) absolute positioning of a set of machined spheres with a known relationship to the part by the lidar measurement, or (2) alignment with a set of features. As mentioned above, camera search allows for rapid feature finding. For machined spheres, confocal lidar offers an additional advantage. The camera can be used to center the lidar on the machined sphere. In all algorithms, it is generally assumed that the radius of the machined sphere is known, such that surface measurements of the machined sphere can be projected onto the center of the machined sphere. After centering, four different algorithms can be used: (1) for a shiny sphere, assuming the camera has correctly centered the lidar and simply measuring the distance to the surface; (2) for a shiny sphere, performing a W-shaped lidar scan to determine the precise angle to the sphere, then measuring the distance to the surface; (3) for a matte sphere, assuming the camera has correctly centered the lidar and simply measuring the distance to the surface; and (4) for a matte sphere, scanning the surface and then performing sphere fitting to determine the position of the sphere. In all cases, camera-centricity improves speed and overall productivity.

[0152] Cameras can be combined with lidar distance measurement to measure features (such as machined spheres). Furthermore, cameras can measure planar features such as holes, slots, polygons, etc. For these types of measurements, only a void exists at the center of the feature. Therefore, the lidar system must intentionally offset the camera's field of view to point towards the surface surrounding the feature.

[0153] Example 22

[0154] refer to Figure 21 The diagram illustrates a representative tracking target 2100. The tracking target 2100 is based on a sphere 2101 having concentric rings 2102, 2104 defined on the sphere. Rings 2102, 2104 have different colors, reflectivities, surface finishes, patterns, or other features easily visible in camera images. Other portions 2106, 2108 of the target may share a common surface color or finish. In some cases, portions 2106, 2108 are glossy and highly reflective, while rings 2102, 2104 have different colors. Such a tracking target may have one, two, three, or more rings. From the viewpoint of the appearance of such a tracking target, it is referred to herein as an "eye sphere" or "ES".

[0155] Figure 22A representative method 2200 using an ES is illustrated. The ES must first be positioned within the camera's field of view at 2202 using a lidar search, for example, using a spiral or angular search, which may have portions outside the camera's field of view. In some cases, the operator can adjust the target or lidar position. At 2204, the ES is tracked using a confocal camera. The ES can be tracked (or the tracking error is reduced) by maintaining a ring centered on the camera's field of view. As the ring moves away from the center of the field of view, one or more motors in the lidar are commanded to orient the lidar (and the confocal camera) to minimize the error. The speed of movement is continuously calculated, and once the speed falls below a threshold, the ES is declared to be no longer moving at 2206. Then, at 2208, a measurement of the sphere's position is triggered. The returned measurement is the center of the sphere. Typically, the measurement of interest is a surface, and the sphere measurement is projected onto that surface.

[0156] While ES is particularly convenient, other tracking targets can be used, such as corner prisms mounted in a sphere (called "spherically mounted retroreflectors" or "SMRs"). Such targets should have a corner prism reflection point at the center of the sphere; otherwise, errors may occur. Unlike SMRs, ES does not exhibit misalignment in response to misoperation. Individual areas of an ES can be painted, etched, frosted, or coated with reflective, metallic, dichroic, or other coatings.

[0157] ES or other target tracking allows for the measurement of target areas with high angles of incidence to the LiDAR 2304 or those that are concealed. (Reference) Figure 23 The tracking target 2302 is displayed in different positions, allowing the detection beam 2301 from the lidar 2304 to reach another hidden area 2310 of the target 2308.

[0158] In some examples, the precision sphere is modified by adding rings of different colors to form an ES. The rings can also be filled with reflective paint to make them very visible under flash. The sphere can be made of a matte material or be luminous, resulting in three measurement modes: (1) using the angle from the camera and the distance to the center of the sphere from the lidar, (2) a matte sphere fitted onto the surface of the sphere, or (3) a W-shaped lidar scan at a mirror point to find the angle and then measuring the distance to the mirror point. In modes 2 and 3, the lidar performs all measurements, and the camera centers the lidar on the sphere and detects that the sphere is not moving. In mode 1, the camera is still used to track and detect no movement; however, the camera's angle measurement is combined with the LR measurement, making the measurement almost instantaneous.

[0159] Example 23

[0160] Another type of hidden point tool can also be used in conjunction with tracking. For example... Figure 24As shown, vector bars 2400 can be created. If the centers of ES 2410 and 2412 are measured by lidar 2404 using probe beam axes 2416 and 2417, the results can be projected onto the center or measurement point of the measuring sphere 2403. This measurement can be referred to as stadium measurement. A complete 6DOF tool with three eyeballs positioned at different locations can be created, and these eyeballs do not necessarily have to be collinear.

[0161] For two eyeballs, two measurements are taken: the XYZ positions of the two eyeballs (XYZ1, XYZ2). The distance between XYZ1 and XYZ2 is not critical, but the distance D between ES 2512 and measuring ball 2403 is crucial. m It must be known. Good measurement results are obtained if the centers of all three spheres are collinear. The center of the measuring sphere 2403 is projected onto the surface of the target using conventional techniques. The XYZ sample of the measuring sphere 2403 is calculated as follows:

[0162]

[0163] This measurement is practical because the low latency allows for measurement of each sphere within a fraction of a second. While a tool with two fixed, separate eyeballs and a measuring sphere is convenient, this tool can also be used with a single eyeball capable of moving to different positions along axis 2414. Measurements can then be taken at each position.

[0164] Example 24

[0165] Automated measurement systems using LiDAR can often involve expensive and time-intensive setup processes, taking weeks to complete and requiring skilled personnel. This paper discloses a system utilizing a metric-grade high-definition (HD) or other camera embedded in a LiDAR. Machine learning algorithms are provided for identifying and / or measuring features such as holes, slots, pillars, and other characteristics. So-called “collaborative robots” (typically including mirrors or other optical systems) allow for blind-spot measurement and local tracking of the measuring device to reduce setup time and accelerate measurement time.

[0166] In some publicly available examples, there is no need for a machined sphere placed around the part to be measured, and augmented reality applications can overlay CAD images and camera images of the part. This allows for automated part detection and can be used to guide LiDAR measurements / scans of selected target areas. The need for lengthy LiDAR scans to locate the area of ​​interest is then eliminated. For some applications, an additional reflector is used with LiDAR to measure hidden or hard-to-reach points not in the direct line of sight. Such reflectors are typically small, thus providing a limited field of view from a fixed location. By attaching such a reflector to a robot, this limited field of view can be greatly extended through automated movement. Using a collaborative robot allows for easy positioning of the reflector, and there is no need to protect the measurement area for safety. Therefore, a collaborative robot can position the reflector in multiple, repeatable, and stable locations, allowing for a larger field of view than a static reflector position, and also allowing for more measurements from a single LiDAR location.

[0167] refer to Figure 25A The reflector 2506 is mounted to the tool flange 2507 of the collaborative robot (COBOT) 2504. Typically, a COBOT includes one or more translation stages and one or more rotary stages, allowing the reflector 2506 to be positioned at a selected location and angle. In some examples, a machining ball 2528 is attached at an offset to the front of the reflector 2506 on a rigid shaft. (Although a machining ball is used in this example, systems including measuring cameras do not require a machining ball.) The lidar 2500 is positioned in a single fixed location or fixed to a programmable positioner, allowing the lidar 2500 to be repeatedly positioned. The position of the reflector 2506 is programmed into the robot 2504 manually or using simulation software, making hidden features of the object to be measured visible from the selected lidar position. Figure 25B As shown, the initial position of the machining ball 2528 is measured directly and indirectly (i.e., via reflection from the machining ball 2528 in the reflector 2506) using a lidar 2500 to determine the nominal position of the machining ball 2528, and the surface of the reflector 2506 is defined by the perpendicular bisector of the line connecting the center of the machining ball 2528 and the image of the machining ball in the reflector 2506. In addition to the movement of the COBOT 2504, the arm 2505 to which the tool flange 2507 is fixed can be moved to approach additional positions on the object 2508.

[0168] After this setup, the COBOT 2504 can be driven to each of several programmed positions, and the LiDAR 2500 can automatically measure the machined sphere based on previously obtained nominal values. This allows for the automatic and accurate determination of the mirror position used for sample measurement. In some cases, where lower accuracy is often sufficient, robot repeatability may be adequate.

[0169] To coordinate mirror measurements and COBOT positioning, digital or physical I / O from the COBOT is provided with a direct connection to the measurement PC or via a programmable logic controller (PLC) based on an OPC, Profinet, or other standard PLC interface. The interface software on the PC can coordinate with movement and positioning signals from the COBOT and measurement signals from the LiDAR. This can include standalone software platforms that connect to teach other software platforms, or it can be part of a single software suite to control communication with the PLC and the LiDAR itself.

[0170] The combination of COBOT 2504 and reflector 2506 with the attached machining ball 2528 allows for faster measurements, measurements utilizing reduced LiDAR or part repositioning, and a reduced number of machining ball measurements required. Multiple reflector positions can be used for a single LiDAR location, and the reflector can be moved during additional measurements of the part, reducing dead-zone measurement time, or simultaneously during repositioning movements. COBOT 2504 does not necessarily require safety fencing or partitioning, and can therefore be placed close to the part, even when the operator is nearby. Automatic cleaning of reflector 2506 can be based on force feedback from the COBOT 2504 via the pad, or force feedback from an air comb or blower, to prevent material deposits on the reflector surface.

[0171] Figure 25A The diagram shows representative machined balls 2520 to 2523 positioned at the object being measured 2508, in addition to the machined ball 2528 in COBOT 2504. The machined balls 2528 and 2520 to 2523 can be irradiated along their respective axes 2510 and 2511 to 2514 in response to a beam scan from the scanning surface 2501.

[0172] Example 25

[0173] A targeting camera / LiDAR system allows for the acquisition of a target image by stitching together multiple images associated with different parts of the target. Each camera image can be associated with the target distance obtained using LiDAR, and any camera tilt can be compensated for using features of the known shape as described above. Figure 26In the representative method 2600 shown, at 2602, a confocal lidar is positioned at a fixed location, and at 2604, an image of at least a portion of the target is acquired. At 2606, the distance to the target portion is measured using the lidar probe beam. At 2608, the acquired image and associated distance, azimuth, elevation, and lidar position coordinates are stored. At 2610, it is determined whether additional images are expected. If so, image acquisition is repeated, with the lidar position set at 2602. The lidar position can remain fixed to a previous position or a newly selected position. If all expected images have been acquired, the images are stitched together at 2612 to form an image of a larger target area. This image can be used to locate specific target features, provide feature measurements, identify target areas for additional lidar measurements, or for other purposes. In a typical example, the lidar is repositioned once or multiple times to produce a full view of the target under evaluation.

[0174] In some cases, image stitching produces excellent results after camera / probe beam calibration. For example, in some examples, the center of the camera's field of view is determined based on one or more images, which include image portions corresponding to the positions of the probe / tracking beam incident on the target. In another example, images of a grid pattern can be evaluated to determine image distortion introduced by the projection lens used by the camera and the probe beam. This distortion can be corrected or compensated for for the images to be stitched.

[0175] Example 26

[0176] refer to Figure 27A representative control and measurement device 2700 for use with a lidar such as a confocal lidar 2704 includes a measurement controller 2706 and an embedded feature processor 2708. One or both of these can be implemented in one or more central processing units, FPGAs, ASICs, or as a system-on-a-chip (SoC). As shown, one or more features are included in a feature set 2710 communicated to the measurement controller 2706. For each feature, the measurement controller communicates a request for the corresponding scan path to the feature processor 2708. The scan path is returned, and the lidar 2704 performs an appropriate scan, and the lidar measurement data is returned to the feature processor 2708. Upon receiving satisfactory measurement data, the feature processor 2708 communicates measurement completion to the measurement controller 2706. Similar message passing is performed for each feature in the feature set 2710, and data processing for one or more scan paths can be performed concurrently with the scanning of one or more other scan paths. The feature set 2710 can include specifications of various target features, such as part dimensions, hole sizes and locations, part shapes, orientations, etc. The scan data returned from the lidar 2704 may include laser distance data and / or image data obtained with a confocal camera.

[0177] Example 27

[0178] In lidar systems incorporating appropriate imaging systems (such as high-resolution cameras), the lidar probe beam can be guided to the area of ​​interest based on features selected from a target image. In this type of measurement, a machining ball is not required. Furthermore, the target design (e.g., a CAD image) can be overlaid with or otherwise displayed on camera images used for part evaluation. The features to be evaluated can be identified from the camera images and the scan paths generated for feature measurements. The lidar can then be driven by these scan paths for part evaluation. As shown above, a reflector positioned at the collaborative robot can be used for measurement, which would otherwise be impossible without repositioning the lidar. In some cases, the collaborative robot is controlled based on the selected scan path. The collaborative robot can be positioned in spaces requiring stringent safety measures for human operators, thus simplifying the measurement process. In some cases, the position of the lidar or other measuring devices can be determined using GPS, gyroscopes, and / or accelerometers; in others, this tracking can eliminate the need for a machining ball for alignment.

[0179] In contrast, traditional LiDAR requires four machining balls to be positioned on the part at each robot location, and typically 10 or more robot locations are needed. LiDAR, as disclosed herein, which can be aligned without machining balls, allows for rapid and simple part setup and measurement. Using the camera described above, machine learning can be used to detect features and identify those that appear to be in the wrong position, and adjust feature parameters without relying on the assumption that the part conforms to the corresponding CAD design.

[0180] Example 28

[0181] Figure 28 A representative manufacturing system 2800 is shown, suitable for producing one or more components of ships, aircraft, or other systems or transposed components, and suitable for evaluating and reprocessing these manufactured components. System 2800 typically includes a shape or profile measurement system 2805, such as the lidar system discussed above. Manufacturing system 2800 also includes a design system 2810, a forming system 2820, a controller 2830, and a repair system 2840. Controller 2830 includes a coordinate storage device 2831 configured to store measured and design coordinates or other characteristics of one or more manufactured structures that are designed and / or measured. Coordinate storage device 2831 is typically a computer-readable medium, such as a hard disk, random access memory, or other memory device. Typically, design system 2810, forming system 2820, shape measurement system 2805, and repair system 2840 communicate via communication bus 2815 using a network protocol.

[0182] Design system 2810 is configured to create design information corresponding to the shape, coordinates, dimensions, or other features of the structure to be manufactured, and to transmit the created design information to forming system 2820. Furthermore, design system 2810 can transmit design information to coordinate storage device 2831 of controller 2830 for storage. Design information typically includes coordinates indicating some or all of the features of the structure to be manufactured.

[0183] Forming system 2820 is configured to generate a structure based on design information provided by design system 2810. The forming process provided by forming system 2820 may include casting, forging, cutting, or other processes. Shape measurement system 2805 is configured to measure the coordinates of one or more features of the manufactured structure and to transmit information indicating the measured coordinates or other information related to the shape of the structure to controller 2830.

[0184] The manufacturing inspector 2832 of the controller 2830 is configured to obtain design information from the coordinate storage device 2831 and compare information such as coordinates or other shape information received from the contour measuring device 100 with the design information read from the coordinate storage device 2831. The manufacturing inspector 2832 is typically provided as a processor and a series of computer-executable instructions stored in a tangible computer-readable medium such as random access memory, a flash drive, a hard disk, or other physical device. Based on the comparison of design and actual structural data, the manufacturing inspector 2832 can determine whether the manufactured structure is formed according to the design information, typically based on one or more design tolerances that can also be stored in the coordinate storage device 2831. In other words, the manufacturing inspector 2832 can determine whether the manufactured structure is defective or not. When the structure is not formed according to the design information (and is defective), the manufacturing inspector 2832 determines whether the structure is repairable. If repairable, the manufacturing inspector 2832 can identify the defective portion of the manufactured structure and provide appropriate coordinates or other repair data. Manufacturing inspector 2832 is configured to generate one or more repair instructions or repair data and forward them to repair system 2840. This repair data may include the location requiring repair, the degree of reshaping required, or other repair information. Repair system 2840 is configured to address defective portions of the manufactured structure based on the repair data.

[0185] Example 29

[0186] Figure 29 It shows that it can be combined with, for example Figure 28 The flowchart illustrates a representative manufacturing method 2900 of the manufacturing system. At 2902, design information corresponding to the shape of the structure to be manufactured is obtained or created. At 2904, the structure is manufactured or "shaped" based on the design information. At 2906, the coordinates, dimensions, or other features of the manufactured structure are measured using a contour measurement system (such as the aforementioned lidar system) to obtain shape information corresponding to the manufactured structure. At 2908, the manufactured structure is inspected based on a comparison of actual and design dimensions, coordinates, manufacturing tolerances, or other structural parameters. At 2910, if the manufactured structure is determined to be defect-free, the manufactured part is accepted at 2914, and processing ends. If, at 2910, for example, the manufacturing inspector 1932 of the controller 1930 determines that the manufactured part is defective, such as... Figure 19 As shown, at point 2912, it can be determined whether the manufactured part is repairable. If it is repairable, the manufactured part is reworked or repaired at point 2916, and then measured, inspected, and re-evaluated at points 2906, 2908, and 2910 respectively. If it is determined at point 2912 that the manufactured part is not repairable, the process ends at point 2914.

[0187] according to Figure 29 This method uses a contour measurement system to accurately measure or evaluate the coordinates or other features of a manufactured structure, allowing for the assessment of whether the structure is defective or not. Furthermore, if the manufactured structure is determined to be defective, a reprocessing process can be initiated if the part is deemed repairable based on its design and actual structural dimensions and features. By repeating the measurement, inspection, and evaluation process, defective parts can be reprocessed, and defective but irreparable parts can be discarded. Figures 28 to 29 The specific systems and methods described are merely exemplary and other arrangements may be used.

[0188] In the above embodiments, the structure manufacturing system 2800 may include a contour measurement system, such as a lidar and associated optical system disclosed herein, a design system 2810, a forming system 2829, a controller 2830 (inspection device) configured to determine whether a part is acceptable, and a repair system 2840. However, other systems and methods may be used, and are provided... Figures 28 to 29 Examples are provided for illustrative purposes.

[0189] Example 30

[0190] Figures 30A to 30B An additional embodiment of a reference component for the laser-based measurement system described above is shown. (Reference) Figure 30AThe reference arm assembly 3000 includes vacuum-rated fiber feedways 3002 to 3005 coupled to a hermetically sealed housing 3002, which is typically evacuated or filled with an inert gas. Fiber feedways 3002, 3003, and 3004 are typically coupled to a pointing or tracking laser 3008, a probe laser 3009, and a reference detector 3010, respectively. Fiber feedway 3002 delivers the tracking beam to a first coupler 3012; fiber feedway 3003 delivers the probe beam to an isolator 3014, which then couples the probe beam back to the first coupler 3012. The combined probe / tracking beam is guided from the first coupler 3012 to fiber feedway 3005 and then to a fiber optic connector, such as an FC / APC connector 3016, for delivery to a suitable scanning, focusing, and detection system as described above. A first coupler 3012 directs a portion of the probe beam from isolator 3014 to a second coupler 3020, which splits this portion of the beam into first and second portions propagating along respective paths 3022A and 3022B. If desired, a fiber delay length 3080 can be positioned between fiber feedthrough 3003 and isolator 3014 such that reflections from internal components (e.g., in the probe laser) produce heterodyne frequencies beyond the typical measurement distance. Paths 3022A and 3022B typically provide a stable, fixed path difference by including an additional fiber length in one of these paths. A third coupler 3024 receives the first and second beam portions from paths 3022A and 3022B, combines these portions, and directs the combined portion via fiber feedthrough 3004 to reference detector 3010. The fixed path difference allows for the correlation of the beat frequency signal between the first and second beam portions with a specific length.

[0191] The housing 3002 is typically made of copper and its temperature is controlled by a thermoelectric (TEC) module 3083 and control electronics 3084. The exterior of the housing 3002 is typically provided with insulation (not shown) surrounding the housing 3002 to insulate it from the surrounding environment. The housing 3002 has a cap sealed with bolts and O-rings. A tube 3082 may be provided for evacuating or filling the housing 3002 with an inert gas or other gas such as nitrogen. The tube 3082 may be positioned on the housing cap and is made of copper. After evacuating or filling the housing 3002, this tube is typically clamped or otherwise sealed. Copper is a convenient material, but other materials may also be used. In some cases, the housing is filled with dry gas.

[0192] refer to Figure 30BThe reference arm assembly 3040, used in conjunction with the dual probe beams, includes fiber feedthroughs 3043A to 3043F coupled to a hermetically sealed housing 3042, which is typically evacuated or filled with inert gas. Fiber feedthroughs 3043A, 3043B, 3043C, 3043D, and 3043F are typically coupled to a pointing or tracking laser 3048, a first probe laser 3049A, a second probe laser 3049B, a first reference detector 3050A, and a second reference detector 3050B, respectively. Fiber feedthrough 3043A delivers the tracking beam to a first coupler 3052; fiber feedthroughs 3043B to 3043B deliver the probe beam to isolators 3054A to 3054B, which then couple the probe beam to a second coupler 3055. The combined probe beam is guided from the second coupler 3055 to the first coupler 3052, and the combined probe / tracking beam is guided to the fiber feedthrough 3043F, and then to a fiber optic connector such as the FC / APC connector 3056 for delivery to the appropriate scanning, focusing, and detection system. The fiber coupler 3052 includes an unused output 3090 and is terminated to reduce or eliminate back reflection at 3070.

[0193] The second coupler 3055 guides a portion of the combined probe beam from isolators 3054A and 3054B to a third coupler 3060, which splits the combined beam portion into first and second parts propagating along corresponding paths 3062A and 3062B. If desired, fiber delay lengths 3045A and 3045B can be positioned between fiber feedpasses 3043B and 3043C and isolators 3054A and 3054B. Paths 3062A and 3062B typically have a stable, fixed path difference, provided by including an additional fiber length 3047 in one of these paths. The third coupler 3064 receives the first and second beam portions from paths 3062A and 3062B, combines these portions, and guides the combined portion via fiber feedpasses 3043D and 3043E to corresponding reference detectors 3050A and 3050B. The fixed path difference allows for the correlation of the beat frequency signal between the first and second beam portions with a specific length. In most practical examples, optical filters 3080A and 3080B are positioned such that reference detector 3050A receives only the beam portion of a first wavelength provided by the first probe laser 3049A, and reference detector 3050B receives only the beam portion of a second wavelength provided by the second probe laser 3049B. For example, the first and second wavelengths can be approximately 1550 nm and 1560 nm, respectively. Fiber delay lengths 3045A and 3045B can be positioned between fiber feedpasses 3043B and 3043C and isolators 3054A and 3054B, such that reflections from internal components generate heterodyne frequencies beyond the normally measured distance. A wavelength demultiplexer coupler can be used instead of the third coupler 3064 and optical filters 3080A and 3080B to separate wavelengths.

[0194] exist Figures 30A to 30B In the example, the fiber used for probing the beam is typically a polarization-preserving single-mode (PRSM) fiber; for tracking the beam, PRSM fibers are typically not used. The length difference used to establish the heterodyne frequency typically uses fibers with lengths between 1m and 200m, usually 5, 10, 15, 20, 25, or 50m.

[0195] Example 31

[0196] refer to Figure 31A representative lidar system 3100 with confocal imaging includes a beam splitter 3104 that guides a probe and track beam along axis 3101 to a first lens 3106, and then to a waveplate 3108, which can be used to generate a local oscillation (LO) beam through reflection as described above. The LO beam can also be generated in other ways, and reflection from waveplate 3108 is merely a convenient example. The probe / track beam is then guided through a beam splitter, such as a cube beam splitter 3110 (or a planar beam splitter or a double-reflection beam splitter as described above), to an objective lens 3112 comprising a fixed lens portion 3116 and a movable (focusing) lens portion 3114. A beam scanner 3120 receives the focused probe / track beam and guides it to a target. An image sensor 3122 is positioned on axis 3101, enabling the lidar to provide confocal imaging. A focus controller 3124 is coupled to an image sensor 3122 and provides autofocus for an image from the target by adjusting a movable lens 3114 using a translation stage or other translation mechanism 3126. The return portion of the probe beam is directed to a beam splitter 3104 and then to a detector 3128. The heterodyne or other signal generated at the detector 3128 allows for the characterization of the target surface.

[0197] As the probe beam scans various target areas, autofocus provided by the focus controller and translation mechanism 3126 allows the probe beam to remain in focus. In conventional systems, establishing focus on the target can be time-consuming. Using a confocal image sensor allows for rapid focus adjustment using the target image generated at image sensor 3122. Therefore, focus can be established and adjusted, and the probe beam can be directed to any selected portion of the field of view using image sensor 3122 and focus controller 3124. Non-transitory computer-readable storage or network connection 3130 receives images from image sensor 312 for processing to identify features and stitch the images together to provide a panoramic image of the target.

[0198] Example 32

[0199] Figure 32 This illustrates a representative method for tracking a machined ball (or tracking target feature) fixed to a substrate or target. One or more machined balls may be fixed to the target to provide a reference point for coordinate determination. The machined balls typically include a reflective spherical surface to provide sufficient reflection of the interrogation beam in laser-based measurement devices such as lidar.

[0200] like Figure 32As shown, at 3202, based on the return portion of the scanned probe beam, the position of the machined ball is identified and recorded. The scan beam can be in various patterns (such as circular, spiral, W-shaped, or zigzag) to track the machined ball. At 3204, the identified position is evaluated to determine its position relative to the main scan. At 3206, the main scan is adjusted so that the position of the machined ball is in a preferred position relative to the main scan. Typically, the main scan is adjusted so that the machining position is approximately centered within the main scan range. At 3208, a determination is made regarding additional scans.

[0201] Example 33

[0202] Figure 33 The following discussion aims to provide a brief overview of exemplary computing environments in which the disclosed techniques, including any of the methods described above, can be implemented. Although not strictly required, the disclosed techniques are described within the general context of computer-executable instructions, such as program modules, executed by a personal computer (PC). Typically, program modules include routines, programs, objects, components, data structures, etc., that perform specific tasks or implement specific abstract data types. Furthermore, the disclosed techniques can be implemented using other computer system configurations, including handheld devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframes, etc. The disclosed techniques can also be practiced in distributed computing environments, where tasks are performed by remote processing devices linked via a communication network. In distributed computing environments, program modules can reside in both local and remote memory storage devices.

[0203] refer to Figure 33 An exemplary system for implementing the disclosed technology includes a general-purpose computing device in the form of an exemplary conventional PC 3300, which includes one or more processing units 3302, system memory 3304, and a system bus 3306 that couples various system components, including the system memory 3304, to the one or more processing units 3302. The system bus 3306 can be any of several types of bus architectures, including a memory bus or memory controller, a peripheral bus, and a local bus using any of the various bus architectures. The exemplary system memory 3304 includes a read-only memory (ROM) 3308 and a random access memory (RAM) 3310. A basic input / output system (BIOS) 3312, containing basic routines that facilitate the transfer of information between components within the PC 3300, is stored in the ROM 3308. The memory 3304 also includes portions 3371 to 3373, which include computer-executable instructions and data for shape recognition and processing, lidar and COBOT control and communication, and design data acquisition, respectively.

[0204] The exemplary PC 3300 also includes one or more storage devices 3330, such as a hard disk drive for reading from and writing to a hard disk, a disk drive for reading from or writing to a removable hard disk, and an optical disc drive for reading from or writing to a removable optical disc (such as a CD-ROM or other optical media). Such storage devices can be connected to the system bus 3306 via a hard disk drive interface, a disk drive interface, and an optical disc drive interface, respectively. The drives and their associated computer-readable media provide the PC 3300 with non-volatile storage of computer-readable instructions, data structures, program modules, and other data. Other types of computer-readable media that can store PC-accessible data (such as magnetic tape, flash memory cards, digital video discs, CDs, DVDs, RAM, ROM, etc.) may also be used in the exemplary operating environment.

[0205] Multiple program modules can be stored in storage device 3330, which includes the operating system, one or more applications, other program modules, and program data. Users can input commands and information to PC 3300 through one or more input devices 3340 (such as a keyboard) and pointing devices (such as a mouse). Other input devices may include digital cameras, microphones, joysticks, game controllers, satellite dishes, scanners, etc. These and other input devices are typically connected to one or more processing units 3302 via a serial port interface coupled to system bus 3306, but may also be connected via other interfaces such as parallel ports, game ports, or Universal Serial Bus (USB). Monitor 3346 or other types of display devices are also connected to system bus 3306 via an interface such as a video adapter. Other peripheral output devices, such as speakers and printers (not shown), may be included.

[0206] PC 3300 can operate in a networked environment using logical connections to one or more remote computers (such as remote computer 3360). In some examples, this includes one or more network or communication connections 3350. Remote computer 3360 can be another PC, server, router, network PC, or peer device or other common network node, and typically includes many or all of the aforementioned elements associated with PC 3300, although only one memory storage device 3362 is present. Figure 33 As shown in the diagram, the personal computer 3300 and / or the remote computer 3360 can connect to a logical local area network (LAN) and a wide area network (WAN). This type of network environment is common in offices, enterprise-distance computer networks, intranets, and the Internet.

[0207] When used in a LAN network environment, the PC 3300 connects to the LAN via a network interface. When used in a WAN network environment, the PC 3300 typically includes a modem or other device for establishing communication over the WAN (e.g., the Internet). In a networked environment, program modules or portions thereof associated with the PC 3300 may be stored on remote storage devices or other locations on the LAN or WAN. The network connections shown are exemplary, and other methods for establishing communication links between computers can be used.

[0208] Given that the principles of the disclosed technology can be applied to many possible embodiments, it should be understood that the embodiments shown are merely preferred examples and should not be considered as limiting the scope of this disclosure.

Claims

1. A measurement apparatus comprising: a beamsplitter positioned to receive a probe beam propagating along an axis; an objective positioned on the axis to receive the probe beam from the beamsplitter and direct the probe beam along the axis to a target, the objective comprising at least one movable optical element; and an image sensor optically coupled to the beamsplitter and positioned on the axis to receive an imaging beam from the target via the beamsplitter, wherein the at least one movable optical element focuses the probe beam at the target and focuses the imaging beam from the target at the image sensor to form a target image.

2. The measuring device of claim 1, wherein, The at least one movable optical element is positioned between the beamsplitter and the target.

3. The measurement apparatus of claim 1, further comprising: an optical fiber positioned to direct the probe beam and a tracking beam along the axis to the beamsplitter, wherein the beamsplitter is a dichroic beamsplitter and the objective comprises a fixed lens and the at least one movable optical element.

4. The measurement apparatus of claim 1, further comprising an autofocus mechanism coupled to the at least one movable optical element to focus the target image at the image sensor and the probe beam at the target.

5. The measuring device of claim 1, wherein, The probe beam is focused by the at least one movable optical element near a center of a field of view of the image sensor.

6. The measurement apparatus of claim 1, further comprising a focus controller coupled to the movable optical element and configured to adjust a focus of the probe beam and the imaging beam.

7. The measurement apparatus of claim 6, further comprising a beam scanner positioned to direct the probe beam to the target and the imaging beam to the image sensor.

8. The measurement apparatus of claim 7, further comprising an image processor coupled to the image sensor and the beam scanner such that a selected portion of the target is imaged at the image sensor in a predetermined location of a sensor surface of the image sensor.

9. The measuring device of claim 8, wherein, The predetermined location is a center location of the sensor surface of the image sensor.

10. The measurement apparatus of claim 7, further comprising an image processor coupled to the image sensor and the beam scanner such that the probe beam is directed to a selected portion of the target based on a target image produced by the image sensor.

11. The measurement apparatus of claim 1, further comprising a probe beam lens positioned to direct the probe beam to the objective, the probe beam lens positioned such that the probe beam and the imaging beam are focused at the target and the image sensor, respectively.

12. The measuring device of claim 1, further comprising an optical fiber having a fiber end positioned to direct the probe beam to the beam splitter, wherein, The image sensor and the fiber end are optically conjugate at one or more wavelengths associated with the imaging beam.

13. A method of measurement, comprising: directing a ladar probe beam along an axis to an objective lens, the objective lens including at least one movable optical element, the at least one movable optical element of the objective lens positioned to focus the ladar probe beam at a target; and directing an imaging beam along the axis from the target to the at least one movable optical element of the objective lens and via a beamsplitter to and in focus at an image sensor, wherein the image sensor is positioned such that the at least one movable optical element of the objective lens produces an image of at least a portion of the target at the image sensor.

14. The measuring method according to claim 13, wherein, the at least one movable optical element positioned between the beamsplitter and the target.

15. The method of measurement of claim 13, further comprising focusing the ladar probe beam at the target based on a contrast of the image of the target formed at the image sensor.

16. The method of measurement of claim 13, further comprising adjusting a focus of the probe beam at the target based on the image of the target formed at the image sensor.

17. The method of measurement of claim 13, further comprising estimating a distance to the target based on a returned portion of the probe beam.

18. The method of measurement of claim 13, further comprising estimating a size of a target feature based on the estimated distance to the target and the image of the target.

19. The method of measurement of claim 13, further comprising utilizing an image processor to find a specified portion of the target in the image and center the specified portion, thereby directing the probe beam to the specified portion of the target.

20. The method of measurement of claim 13, utilizing a processor coupled to the image sensor, measuring at least one target dimension using an angle determined based on a target distance.

21. The method of measurement of claim 13, further comprising estimating at least one target dimension based on a target feature size in the target image and a distance to the target.

22. The method of measurement of claim 13, further comprising tracking a moving target based on the image of the at least a portion of the target.

23. The method of measurement of claim 13, further comprising forming a segmented image of the target by obtaining a plurality of images of the target with the image sensor and associated distances to the target determined based on returned portions of the probe beam.

24. The method of measurement of claim 23, further comprising generating a 3D model of the target based on the segmented image.

25. The method of measurement of claim 24, further comprising locating at least one selected target region in the target based on a panoramic image.

26. A measurement apparatus, comprising: a dichroic beamsplitter; an optical fiber positioned to direct a probe beam along an axis to the dichroic beamsplitter; an image sensor positioned to receive an imaging beam from the dichroic beamsplitter; and an image processor coupled to the image sensor. an objective positioned on the axis and including a fixed lens and a movable lens positioned to receive the probe beam from the dichroic beamsplitter and direct the probe beam along the axis to a target; and an image sensor optically coupled to the dichroic beamsplitter and positioned on the axis to receive an imaging beam from the target via the dichroic beamsplitter, wherein the movable lens is translatable to focus the probe beam at the target and the imaging beam from the target at the image sensor to form a target image.

27. The measuring device of claim 26, wherein, The movable lens is positioned between the dichroic beamsplitter and the target.

28. The measuring device of claim 26, wherein, The dichroic beamsplitter is positioned such that the probe beam is transmitted through the dichroic beamsplitter to the movable lens and the imaging beam is reflected by the dichroic beamsplitter to the image sensor.

29. The measuring device according to any one of claims 26 to 28, wherein, The objective is positioned to receive a tracking beam from the dichroic beamsplitter and direct the probe beam and the tracking beam to the target, wherein the probe beam has a wavelength between 1200 nm and 1800 nm and the tracking beam has a wavelength between 400 nm and 700 nm.

30. The measuring device according to any one of claims 26 to 28, wherein, The dichroic beamsplitter is positioned such that the probe beam is reflected by the dichroic beamsplitter to the movable lens and the imaging beam is transmitted by the dichroic beamsplitter to the image sensor.

31. The measuring device according to any one of claims 26 to 28, wherein, The dichroic beamsplitter is a cubic dichroic beamsplitter, a plate dichroic beamsplitter, or a double-reflective dichroic beamsplitter.

32. The measuring device of claim 26, wherein, The dichroic beamsplitter is a double-reflective dichroic beamsplitter including a first surface facing the movable lens and a dichroic reflective surface positioned to direct the imaging beam to the image sensor and a portion of the probe beam returning from the target to the optical fiber.

33. The measuring device of claim 26, wherein, The dichroic beamsplitter is a double-reflective dichroic beamsplitter including a first surface facing the movable lens and a dichroic reflective surface positioned to direct the imaging beam to the first surface such that the imaging beam is reflected by the first surface to the image sensor and a portion of the probe beam returning from the target to the optical fiber is transmitted by the reflective surface to the optical fiber.

34. The measuring device of claim 26, wherein, The dichroic beamsplitter is a double-reflective dichroic beamsplitter including a first surface facing the movable lens and a dichroic reflective surface positioned to direct a portion of the probe beam returning from the target to the first surface and the imaging beam is transmitted by the dichroic reflective surface to the image sensor.

35. The measuring device according to any one of claims 32 to 34, wherein, The first surface is positioned at an angle greater than a critical angle relative to the imaging beam received from the dichroic reflective surface.

36. The measuring device according to any one of claims 32 to 34, wherein, The dual-reflecting dichroic beamsplitter includes an output surface positioned such that the portion of the probe beam returned from the target and reflected by the dichroic reflective surface to the first surface is reflected to be normally incident on the output surface.

37. The measuring device of any one of claims 32 to 34, wherein, The dual-reflecting dichroic beamsplitter includes an output surface positioned such that the imaging beam returned from the target and reflected by the dichroic reflective surface to the first surface is reflected to be normally incident on the output surface.

38. The measuring device of any one of claims 32 to 34, wherein, The dual-reflecting dichroic beamsplitter includes a first prism having an apex angle between the first surface and the dichroic reflecting surface, wherein the apex angle is greater than sin -1 (1 / n), where n is the refractive index of the prism.

39. The measuring device of claim 38, wherein, The dichroic reflective surface of the dual-reflecting dichroic beamsplitter is defined on a surface of the first prism.

40. The measuring device of any one of claims 32 to 34, wherein, The dual-reflecting dichroic beamsplitter includes a first prism and a second prism secured to one another at respective mating surfaces, and the dichroic reflective surface is positioned at the mating surfaces.

41. The measuring device of claim 40, wherein, The dichroic reflective surface is defined on at least one of the mating surfaces.

42. The measuring device of any one of claims 26 to 28, wherein, The dichroic beamsplitter includes a dichroic plate and a planar reflector, wherein the dichroic plate is positioned to direct the portion of the probe beam returned from the target to the planar reflector and to transmit the imaging beam to the image sensor.

43. The measuring device of any one of claims 26 to 28, wherein, The dichroic beamsplitter includes a dichroic plate and a planar reflector, wherein the dichroic plate is positioned to reflect the imaging beam to the planar reflector and to transmit the portion of the probe beam returned from the target.

44. The measuring device of any one of claims 26 to 28, wherein, The optical fiber is a polarization-maintaining single-mode PRSM optical fiber, and further comprising a polarizing beamsplitter PBS positioned such that the probe beam from the PRSM optical fiber is received by the PBS in a polarization state that is substantially transmitted by the PBS to the dichroic beamsplitter.

45. The measuring device of claim 44, wherein, The polarization state is a linear polarization state.

46. The measurement device of claim 44, further comprising a waveplate positioned between the PBS and the dichroic beamsplitter to produce a circular polarization state in the probe beam and to reflect a portion of the probe beam toward the optical fiber to produce a local oscillation beam.

47. The measuring device of claim 46, wherein, The waveplate has an input surface positioned to receive the probe beam from the PBS and an output surface positioned to receive the probe beam from the input surface of the waveplate, wherein one of the input surface or the output surface is anti-reflective coated and the other of the input surface and the output surface reflects a portion of the probe beam as a local oscillation beam.

48. The measurement device of any one of claims 26 to 28, further comprising a hybrid lens positioned to receive the probe beam and tracking beam from the optical fiber and a dichroic filter positioned on an axial portion of the hybrid lens along the axis, wherein, The dichroic filter transmits the probe beam and does not transmit the tracking beam.

49. The measuring device of claim 48, further comprising a dichroic reflector positioned along the axis on an axial portion of the hybrid lens, wherein, The dichroic filter is a dichroic reflector that transmits the probe beam and reflects the tracking beam.

50. The measuring device of claim 48, wherein, The dichroic filter is a wavelength-dependent polarizer that substantially does not transmit the tracking beam.

51. The measurement device of any one of claims 26 to 28, further comprising a mixing lens positioned to receive the probe beam and a tracking beam from the optical fiber and a dichroic reflector positioned on an axial portion of the mixing lens along the axis, the dichroic reflector transmitting the probe beam and reflecting the tracking beam, wherein, The dichroic reflector is sized based on a corresponding size of the image sensor.

52. The measurement device of any one of claims 26 to 28, further comprising a hybrid lens positioned to receive the probe beam and tracking beam and to focus the probe beam; and a dichroic reflector positioned along the axis on an axial portion of the hybrid lens, the dichroic reflector transmitting the probe light beam and reflecting the tracking light beam, wherein, The size of the dichroic reflector is at least 0.5, 0.75, 1.0, or 1.5 times the corresponding size of the image sensor.

53. The measuring device of claim 52, wherein, The size of the dichroic reflector is at least 0.5, 0.75, 1.0, or 1.5 times the product of the corresponding size of the image sensor and a ratio of an optical distance from the hybrid lens focal point to the dichroic reflector to an optical distance from the hybrid lens focal point to the image sensor along the axis.

54. The measuring device of claim 48, wherein, The dichroic filter is positioned on a lens surface of the movable lens.

55. A measurement device comprising: an optical fiber; an imaging lens positioned to receive a measurement beam from the optical fiber and produce a measurement beam focal point; an optical element having a surface positioned near the measurement beam focal point to reflect a portion of the measurement beam back into the optical fiber as a local oscillation beam; and an objective lens comprising at least one movable optical element and positioned to receive the measurement beam from the optical element, the at least one movable optical element of the objective lens directing and focusing a portion of the measurement beam to a target as a probe beam and directing a portion of the probe beam returned from the target through the optical element and the imaging lens into the optical fiber to form a signal beam and focusing an imaging beam from the target at an image sensor to form a target image.

56. The measuring device of claim 55, wherein, The optical element is a waveplate.

57. The measuring device of claim 56, wherein, The waveplate has an entrance surface to receive the measurement beam from the imaging lens and an exit surface opposite the entrance lens, wherein the exit surface is positioned near the measurement beam focal point to reflect the portion of the measurement beam.

58. The measuring device of claim 56, wherein, The waveplate has an entrance surface to receive the measurement beam from the imaging lens and an exit surface opposite the entrance surface, wherein the entrance surface is positioned near the measurement beam focal point to reflect the portion of the measurement beam.

59. The measuring device of claim 56, wherein, One of the entrance surface and the exit surface of the waveplate includes an anti- reflective coating positioned to receive the measurement beam from the imaging lens and the other of the entrance surface and the exit surface has an uncoated portion positioned to receive the focused measurement beam from the imaging lens.

60. The measurement device of claim 56, further comprising a polarizing beam splitter positioned to couple the measurement beam to the waveplate.

61. The measurement device of claim 56, further comprising a polarizing beam splitter positioned to receive the measurement beam from the imaging lens and to couple the measurement beam to the waveplate.

62. The measuring device of claim 61, wherein, The at least one movable optical element is positioned between the polarizing beam splitter and the target.

63. The measuring device of claim 55, wherein, The optical element having the surface positioned near the measurement beam focal point is a polarizing beam splitter PBS.

64. The measuring device of claim 63, wherein, The PBS has an exit surface facing the objective lens and the exit surface of the PBS is positioned at the measurement beam focal point to reflect the portion of the measurement beam back into the optical fiber as the local oscillation beam.

65. The measuring device of claim 55, wherein, The optical element includes a polarizing beam splitter and a wave plate fixed to the polarizing beam splitter PBS.

66. The measuring device of claim 65, wherein, The PBS has an entrance surface coupled to receive the measurement beam from the optical fiber, and the wave plate includes an exit surface positioned to couple the measurement beam from the PBS to the objective lens and reflect the portion of the measurement beam back into the optical fiber as the local oscillation beam.

67. The measuring device according to any one of claims 65 to 66, wherein, The PBS is positioned to reflect a probe beam portion of the measurement beam to the wave plate.

68. The measurement apparatus of any of claims 55-56, further comprising: an optical detector coupled to the optical fiber and positioned to receive the probe beam and the local oscillation beam and produce a heterodyne electrical signal; and a detection system to provide a target distance estimate based on the heterodyne electrical signal.

69. The measurement apparatus of any of claims 55-56, further comprising: first and second measurement beam sources to produce first and second measurement beams of first and second wavelengths, respectively; and a beam combiner to receive the first and second measurement beam sources and couple the first and second measurement beams to form a combined measurement beam, wherein the optical fiber directs the combined measurement beam to the imaging lens and the optical element reflects a portion of the combined measurement beam back toward the optical fiber as first and second local oscillation beams.

70. The measurement apparatus of claim 60 or 61, further comprising: first and second optical detectors coupled to the optical fiber or the polarizing beam splitter to receive portions of the probe beam returned from a target and first and second local oscillation beams to produce first and second heterodyne electrical signals; and a detection system to provide a target distance estimate based on the first and second heterodyne electrical signals.

71. The measuring device of any one of claims 55-56, wherein, a hybrid lens to receive a measurement beam and a tracking beam from the optical fiber, and the hybrid lens further includes a dichroic filter positioned on an axis of the objective lens, wherein the dichroic filter does not transmit the tracking beam.

72. A method of measurement, comprising: directing a tracking beam to a beam splitter, the tracking beam having an associated beam numerical aperture; blocking a portion of the tracking beam numerical aperture so that the beam splitter receives a measurement beam and a partially occluded tracking beam; directing the partially occluded tracking beam from the beam splitter to a target with an objective lens, the objective lens including at least one movable optical element; and The at least one movable optical element is positioned between the beamsplitter and the target.

73. The measuring method according to claim 72, wherein, 74. A method of measurement, comprising: focusing a measurement beam from an optical fiber to a measurement beam focal point; and reflecting a portion of the measurement beam toward the optical fiber to produce a local oscillation beam, directing another portion of the measurement beam as a probe beam to and focusing at a target by an objective comprising at least one movable optical element, and directing a portion of the probe beam returned from the target into the optical fiber by the at least one movable optical element to form a signal beam, and focusing an imaging beam from the target at an image sensor via the at least one movable optical element to form a target image. The measurement beam is focused by a beamsplitter to the at least one movable optical element, the at least one movable optical element having a surface that reflects the portion of the measurement beam to the optical fiber.

75. The measuring method according to claim 74, wherein, The at least one movable optical element is a waveplate, and the surface that reflects the portion of the measurement beam is a surface of the waveplate.

76. The measuring method according to any one of claims 74 to 75, wherein, The at least one movable optical element is a polarizing beamsplitter PBS, and the surface that reflects the portion of the measurement beam is a surface of the PBS.

77. The measuring method according to any one of claims 74 to 75, wherein, 78. A measurement apparatus, comprising: a lidar positioned to direct a probe beam to a target along an axis and to produce an estimate of at least one target dimension, the lidar comprising an objective and a probe beam scanner coupled to scan the probe beam axis, the objective comprising at least one movable optical element; an imager positioned optically along the axis to produce an image of the target from an imaging beam focused by the at least one movable optical element from the target, wherein the probe beam scanner is coupled to the imager to direct the probe beam to a target location based on at least one feature identified in the target image, the at least one movable optical element focusing the probe beam to the target. The imager is an image sensor, and further comprising an image processor that identifies the at least one feature in the target image.

79. The measuring device of claim 78, wherein, The at least one feature is a design feature, and the target location is associated with the design feature.

80. The measuring device of any one of claims 78 to 79, wherein, The at least one feature is a machining ball, and the target location is determined based on a position of the machining ball.

81. The measuring device of any one of claims 78 to 79, wherein, The at least one feature is an eye ball, and the target location is determined based on a position of the eye ball.

82. The measuring device of any one of claims 78 to 79, wherein, 83. A measurement apparatus, comprising: ​ a lidar positioned to direct a probe beam along an axis to a target, the lidar including an objective and a probe beam scanner coupled to scan the probe beam axis, the objective including at least one movable optical element that focuses the probe beam to the target; an imaging system including an image sensor and a focusing mechanism, the image sensor optically positioned along the axis to produce an image of the target from an imaging beam from the target focused by the at least one movable optical element, the focusing mechanism coupled to the at least one movable optical element of the objective to adjust a focus of the target image at the image sensor; and an image processor coupled to the imaging system to produce an estimate of at least one target dimension based on the image of the target and an estimate of a distance to the target.

84. The measuring device of claim 83, wherein, The lidar is configured to produce the estimate of the distance to the target.

85. The measuring device of any one of claims 83 to 84, wherein, The estimate of the distance to the target is based on an adjustment of the focusing mechanism.

86. The measuring device of any one of claims 83 to 84, wherein, The focusing mechanism is an autofocus mechanism.

87. The measuring device of any one of claims 83 to 84, wherein, The image processor identifies at least one feature in the target image.

88. The measuring device of claim 87, wherein, The at least one feature is a design feature, and a target location is associated with the design feature.

89. The measuring device of claim 87, wherein, The at least one feature is a machining ball, and a target location is determined based on a location of the machining ball.

90. The measuring device of claim 87, wherein, The at least one feature is an eye ball, and a target location is determined based on a location of the eye ball.

91. The measuring device of any one of claims 83 to 84, wherein, The imaging system is configured to produce a plurality of image portions, and the image processor is configured to stitch the plurality of image portions into a common image.

92. The measuring device of any one of claims 83 to 84, wherein, The imaging system is configured to produce a plurality of image portions, and the image processor is configured to at least partially compensate for distortion in at least one image portion.

93. The measuring device of any one of claims 83 to 84, wherein, The imaging system is configured to produce a plurality of image portions, and the image processor is configured to at least partially compensate for distortion in at least one image portion based on a test grid image.

94. A measurement apparatus comprising: a lidar including an objective and providing a scanable laser probe beam, the objective including at least one movable optical element that focuses the probe beam to a target; an imaging system including an image sensor and a focusing mechanism, the image sensor optically positioned along an axis to produce a target image from an imaging beam from the target focused by the at least one movable optical element, the focusing mechanism coupled to the at least one movable optical element to adjust a focus of the target image at the image sensor; and a remote mirror system including a translatable mirror, wherein the lidar is configured to direct the scanable laser probe beam to the translatable mirror of the remote mirror system to be reflected to a target to measure at least one feature of the target.

95. The measuring device of claim 94, wherein, The laser radar is positioned to direct the scanable laser probe beam to the remote mirror system and to determine a position of the remote mirror system, wherein the at least one feature of the target is measured based on the remote mirror system position and a portion of the probe beam that returns from the target to the laser radar.

96. The measuring device of any one of claims 94-95, wherein, The remote mirror system includes at least one machined sphere or ophthalmic sphere, and the laser radar is positioned to direct a scanable laser probe beam to the at least one machined sphere or ophthalmic sphere to determine a position of the remote mirror system.

97. The measuring device of claim 95, wherein, The laser radar is coupled to the remote mirror system to initiate adjustment of the translatable mirror so that the scanable laser probe beam is directed to the at least one feature of the target.

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