This document pertains generally, but not by way of limitation, to apparatus and techniques that can be used for optical detection, and more particularly to optical elements such as lenses that can be used in combination with an electro-optical beamsteerer.
Optical systems can be used for a variety of applications such as sensing and detection. An optical detection system generally includes an optical transmitter and an optical receiver. The optical transmitter can include an illuminator module. For example, in a scanned transmit approach, the illuminator module can establish an output beam such as a spot or a line that can be mechanically or electro-optically steered to various locations (e.g., angular positions) to illuminate a field-of-regard (FOR). The optical receiver can capture light that is scattered by or reflected off one or more objects within a receiver field-of-view (FOV). An optical detection system, such as a system for providing light detection and ranging (LIDAR), can use various techniques for performing depth or distance estimation, such as to provide an estimate of a range to a target, such as a range from an optical transceiver assembly. Such detection techniques can include one or more “time-of-flight” determination techniques or other techniques. For example, a distance to one or more objects in a field of view can be estimated or tracked, such as by determining a time difference between a transmitted light pulse and a received light pulse. More sophisticated techniques can be used such as to track specific identified targets within a field of view of the optical detection system. In another example, time information can be encoded, and a LIDAR system can operate using a coherent or continuous wave approach.
Optical detection systems, such as laser range-finding or LIDAR systems, may operate by transmitting light towards a target region, using either a continuous wave or pulsed approach. The transmitted light can illuminate a portion of the target region. A portion of the transmitted light can be reflected or scattered by the illuminated portion of the target region and received by the LIDAR system. The LIDAR system can then determine a distance between the LIDAR system and the illuminated portion of the target region. In a pulsed-light approach, the LIDAR system can measure a time difference between transmitted and received light pulses, as an illustrative example. An optical transmitter in a LIDAR system can include a beam steering element to direct a beam of light to illuminate different regions in a field-of-regard (FOR) addressable by the beam steering element or “beamsteerer.” In one approach, an electro-optical device can be used as a beamsteerer. In an example, such as a “monostatic” configuration, the transmit beamsteerer can also operate to steer detected light (e.g., where the same beamsteerer may operate both as a steering element in the transmit signal chain and a steeling element in the detection signal chain). In such a monostatic example, the optical elements described herein may handle both output light (e.g., in the transmit sense) and input light (e.g., in the receive or detection sense).
An electro-optical beamsteerer, such as a liquid crystal waveguide (LCW) device, can be optically coupled with other optical structures. For example, such optical structures can be used to shape a beam being steered by the beamsteerer or shape a field-of-regard (FOR) addressable from the perspective of the beamsteerer. Optical elements placed at an output or exit of the beamsteerer can be used as a “spot mapper” to increase or decrease the field that can be scanned by the beamsteerer, as an illustrative example. Lenses or other optical elements can also be used to correct distortion in the steered beam distribution across the field-of-regard, such as to provide a “smile corrector.” In a similar manner, optical elements can be placed at an input to the beamsteerer, such as to provide a beam expander to change the size or shape of the beam profile inside the beamsteerer device.
The optical elements can include transmissive macroscale lenses (e.g., “macrolens”) structures, such as polymer or glass lenses, or other optical elements such as planar structures. In macroscale optics, an achievable f-number (represented as “f/#,” and corresponding to a focal length of the lens divided by a diameter of the entrance aperture) is generally limited by the nature of curvatures that can be achieved via molding or machining (e.g., grinding) techniques, along with the refractive indices of the materials available for these processes (such as glass or polymer materials). To overcome such challenges, planar structures can be used, and can include geometric phase lenses comprising a liquid crystal polymer, or planar structures incorporating a grating (e.g., a polarization grating), as illustrative examples.
In an example, an optical system can provide illumination of a field-of-regard for optical detection, the optical system comprising an el electro-optical beamsteerer, and an optical structure configured to adjust at least one of the field-of-regard or a shape of a beam provided by the electro-optical beamsteerer. In an example, the optical structure can include a planar optical structure, such as a polarization grating or geometric phase lens. In another example, the optical structure can include at least two lens structures, such as a converging lens and a diverging lens, In an example, the optical structure can include a prism, such as arranged as an anamorph. Combinations of such examples can also be used for the optical structure.
In an example, a technique such as a method can be used to generate illumination of a field-of-regard for optical detection. The technique can include receiving an input beam from an optical source, electro-optically steering the input beam using an electro-optical beamsteerer, and adjusting at least one of the field-of-regard or a shape of an output beam provided by the electro-optical beamsteerer using an optical structure. In an example, a beam distribution of the output beam provided by the electro-optical beamsteerer can be adjusted. In an example, a beam distribution of the input beam provided to the electro-optical beamsteerer can be adjusted. In an example, the technique can include establishing a distribution of spot sizes that vary across the field-of-regard, such as providing a smaller spot size (corresponding to enhanced resolution) at a center of the field-of-regard as compared to a periphery of the field of regard, using the optical structure.
Generally, the examples described in this document can be implemented in whole or in part within a module or assembly. A module or assembly can include a beamsteerer and related optical structures within a single package, as an illustrative example.
This summary is intended to provide an overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present patent application.
In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.
As mentioned above, an optical detection system can include use of a scanned transmit scheme. For example, an illuminator for the optical system can include a light source such as a laser, and electro-optical beamsteerer. The electro-optical beamsteerer can be coupled with other optical structures. For example, such optical structures can be used to shape a beam being steered by the beamsteerer or shape a field-of-regard (FOR) addressable from the perspective of the beamsteerer. Optical elements placed at an output of the LCW can be used as a “spot mapper” to increase or decrease the field of view that can be scanned by a beam steered by the LCW, as an illustrative example. Lenses or other optical elements can also be used to correct distortion in the steered beam distribution across the field of view, such as to provide a “smile corrector.” In a similar manner, optical elements can be placed at an input to the beamsteerer, such as to provide a beam expander to change the size of the beam profile inside the beamsteerer device.
The beamsteerer 150 can include an input facet 102A for incoupling light 116 into a semiconductor slab 104, and an output facet 102B for outcoupling light 114A or 114B in a direction established by the beamsteerer 150. The slab 104 can include or can overlay a planar LCW cell 107, which, in turn can rest upon an underlying glass or other mounting block such as can be located on the opposing side of the LCW cell 107. The planar LCW cell 107 can include a subcladding and a generally planar Liquid Crystal (LC) core. The subcladding thins in locations underlying the incoupling and outcoupling zones of the slab 104, such as to allow light passage through the subcladding in such zones, The inner surfaces of the slab 104 and the cell 107 or other supporting structure can be coated or implanted with one or more layers, such as for establishing the optical and electronic conditions suitable for beam steering a light beam in a particular specified range of wavelengths.
In the example of
The example of
In a beamsteerer 150 as shown in the illustration of
In the example 200 of
The spot distribution in the far-field need not be uniform. For example, an “irregular” spot distribution can be achieved. In an example, relatively smaller far-field spots can be provided in proximity to the optical axis (e.g., a central axis extending in a longitudinal direction), and the spot size can be relatively larger in a direction extending laterally or vertically away from the axis. In this manner, a foveated scanning scheme can be used, such as to provide enhanced resolution in a central region of the field-of-regard. In the example 200 shown in
The configuration of FIG, 2 can be similar to a Galilean telescope comprising a converging lens 262 and a diverging lens 264. As an illustrative example, the lenses 262 and 265 can have a diameter of 25 millimeters (mm) and a separation of 25 mm from center-to-center, with the converging lens 262 having a focal length of f=+50 mm, and the diverging lens 264 having a focal length of f=25 mm. A ratio between the magnitudes of the focal lengths provides a near-field beam size reduction of a factor of 2 (“2×”).
Along with a reduction in beam size, the configuration shown in
When the beam 414A refracts at prism 470 interfaces, its size can be decreased or increased depending on geometry of the angle of incidence and the refractive index of the prism 470 material. As in the case of the optical lens system in
Generally, the examples above of
Generally, grating structures can include reflective or transmissive gratings. As an example, polarization gratings (PGs) can diffract light into a specific order with high efficiency (e.g., with low or minimal loss associated with coupling of light into unwanted orders). The planar optical structures 562 and 564 can include polarization gratings (“PG structures”) or diffractive waveplates, as illustrative examples. Generally, PG structures are thin (e.g., on the order of micrometers) and can provide high transmissivity, so such structures can be efficiently stacked in a series of two or more for additional beam shaping stages. Other planar structure 562 and 564 can be used, such as geometric phase lenses (GPLs) to provide optical structures including lens behavior, prism behavior, or mirror behavior, and such planar structures can be used in relation to the examples 500A and 500B of
For example,
Generally, for LCW devices used as the beamsteerer 850, a desired beam height and geometry may be determined by the method used to couple light into the waveguide core. For example, a smaller beam height generally allows for a shorter tapered region (e.g., faceted region) of the waveguide core. Such a shorter tapered region facilitates manufacturing of smaller, lower-cost devices. A width of the beam 876 need not be constrained in this manner. For example, a wider beam can provide improved power handling characteristics (e.g., by spreading the beam energy spatially within the waveguide core), which in turn allows for a higher power beam and therefore longer range operation, such as in a LIDAR application. Additionally, wider beams can be steered over more spots in the far field, allowing for higher resolution in LIDAR imaging or targeting.
Each of the non-limiting aspects in this document can stand on its own, or can be combined in various permutations or combinations with one or more of the other aspects or other subject matter described in this document.
The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to generally as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.
In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls.
In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.
Method examples described herein can be machine or computer-implemented at least in part. Some examples can include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform methods as described in the above examples. An implementation of such methods can include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code can include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, in an example, the code can be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like.
The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed. Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
Number | Date | Country | |
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62696156 | Jul 2018 | US |