JP2022540757A - Ultrasonic Sub-Aperture Polishing of Optical Elements - Google Patents

Abstract

Aspects of an ultrasonic polishing system include an ultrasonic actuator and a polishing arm. The ultrasonic actuator is configured to generate ultrasonic vibrations, and the polishing arm is coupled to the ultrasonic actuator. The polishing arm includes a horn and a polishing ball. The horn has a proximal end and a distal end. The proximal end is coupled to receive ultrasonic vibrations, and the horn is configured to propagate the ultrasonic vibrations from the proximal end to the distal end. A polishing ball is attached to the distal end of the horn, where the polishing ball vibrates in response to ultrasonic vibrations that polish the surface of the optical element. The polishing ball is configured to provide a polishing area on the surface of the optical element that is smaller than the aperture of the optical element. [Selection drawing] Fig. 2

Description

Aspects of the present disclosure relate generally to sub-caliber polishing of optical elements, and more particularly, but not exclusively, to ultrasonic sub-caliber polishing of optical elements.

A head-mounted display (HMD) is a display device typically worn on the user's head. HMDs can be used in various applications such as games, aviation, engineering, medicine, and entertainment to provide users with artificial reality content. Artificial reality is a form of reality that has been conditioned in some way before presentation to the user, such as virtual reality (VR), augmented reality (AR), mixed reality (MR), hybrid reality, or any combination thereof. Any combination and/or derivation may be included.

The accuracy of the various optical elements included in HMDs, such as lenses, polarizers, waveplates, etc., may depend on the particular application. For example, some HMDs may incorporate an eye-tracking system that includes an integrated camera that tracks the user's eye movements. Therefore, as the requirements and accuracy for eye-tracking systems increase, so does the precision required in manufacturing the various optical elements used by the eye-tracking system.

According to a first aspect of the invention, there is provided an ultrasonic polishing system for polishing an optical element, the system comprising: an ultrasonic actuator configured to generate ultrasonic vibrations; a polishing arm, the polishing arm being a horn having a proximal end coupled to receive ultrasonic vibrations, the ultrasonic vibrations propagating from the proximal end to the distal end of the horn. and a polishing ball attached to the distal end of the horn, configured to vibrate in response to ultrasonic vibrations that polish a surface of the optical element; a polishing ball configured to provide a polishing area on the surface of the optical element that is smaller than the aperture.

In some embodiments, the aperture of the optical element is 3 millimeters or less.

In some embodiments, the abrasive region has a diameter of 10 microns or less.

In some embodiments, the polishing ball has a spherical shape.

In some embodiments, the polishing ball comprises sapphire.

In some embodiments, the polishing arm has a natural frequency that matches the frequency of the ultrasonic vibrations.

In some embodiments, the frequency of ultrasonic vibration is 20 kHz or higher.

In some embodiments, the frequency of ultrasonic vibration is between 20 kHz and 40 kHz.

In some embodiments, the ultrasonic polishing system further comprises a computer numerically controlled (CNC) positioner coupled to the polishing arm to change the position of the polishing ball relative to the surface of the optical element.

In some embodiments, the ultrasonic polishing system further comprises a computing device, the computing device including at least one processor and at least one memory coupled to the at least one processor, wherein at least one A memory stores instructions which, when executed by the at least one processor, generate one or more control signals that direct the CNC positioner to change the position of the polishing ball relative to the surface of the optical element. Inducing a computing device to generate

In some embodiments, the instruction to generate one or more control signals to guide the CNC positioner to change the position of the polishing ball is the instruction to guide the polishing ball along a polishing path on the surface of the optical element. including.

In some embodiments, the instructions to guide the polishing ball along the polishing path include ( Including instructions to change at least one of a) the load applied to the polishing arm, or (b) the velocity of the polishing ball along the polishing path.

In some embodiments, the ultrasonic polishing system further comprises an interferometer arranged to obtain one or more surface measurements of the optical element, wherein the at least one memory is based on the surface measurements. and instructions for directing the computing device to generate a surface error map of the optical element, wherein the instructions to vary the load or velocity are responsive to the surface error map.

In some embodiments, the ultrasonic actuator comprises a magnetostrictive actuator, and the abrasive ball vibrates along an elliptical travel path on the surface of the optical element in response to ultrasonic vibrations generated by the magnetostrictive actuator. is configured as

In some embodiments, the ultrasonic actuator comprises a piezoelectric actuator, and the polishing ball vibrates along a linear travel path on the surface of the optical element in response to ultrasonic vibrations generated by the piezoelectric actuator. is configured as

According to a second aspect of the invention, a method of ultrasonic sub-aperture polishing of an optical element is provided, the method comprising enabling an ultrasonic actuator to generate ultrasonic vibrations; generating one or more control signals to induce a computer numerically controlled (CNC) positioner to change the position of the polishing arm relative to the polishing arm, the polishing arm being subjected to ultrasonic vibrations generated by an ultrasonic actuator; a horn having a proximal end coupled to receive a horn configured to propagate ultrasonic vibrations from the proximal end to the distal end of the horn; An end-mounted polishing ball configured to vibrate in response to ultrasonic vibrations to polish the surface of the optical element to provide a polishing area on the surface of the optical element that is smaller than the aperture of the optical element. a polishing ball configured to.

In some embodiments, changing the position of the polishing ball includes guiding the polishing ball along a polishing path on the surface of the optical element, the method comprising: Varying at least one of (a) the load applied to the polishing arm or (b) the velocity of the polishing ball along the polishing path to adjust the amount of material removed from the surface of the optical element in Generating one or more additional control signals to guide the CNC positioner to.

In some embodiments, the method includes receiving one or more surface measurements of the optical element and generating a surface error map of the optical element based on the surface measurements, wherein the load or velocity is generating a surface error map of the optical element, the altering being responsive to the surface error map.

According to a third aspect of the invention, an ultrasonic actuator is enabled to generate ultrasonic vibrations and a computer numerically controlled (CNC) positioner is used to change the position of the polishing arm relative to the surface of the optical element. and generating one or more guiding control signals, the polishing arm coupled to receive ultrasonic vibrations generated by the ultrasonic actuator. A horn having a proximal end configured to propagate ultrasonic vibrations from the proximal end to the distal end of the horn, and an polish attached to the distal end of the horn. A ball configured to vibrate in response to ultrasonic vibrations that abrade the surface of the optical element and configured to provide an abraded area on the surface of the optical element that is smaller than the aperture of the optical element. , a polishing ball, and a.

In some embodiments, a method comprises receiving one or more surface measurements of an optical element; generating a surface error map of the optical element based on the surface measurements; (a) the load applied to the polishing arm, or (b) the speed of the polishing ball along the polishing path, to adjust the amount of material removed from the surface of the optical element at one or more positions of the arm; generating one or more additional control signals in response to the surface error map to guide the CNC positioner to change at least one of the;

Any feature described herein as suitable for incorporation into any aspect or embodiment of the invention is intended to be generalizable across all aspects and embodiments of the disclosure Please understand.

Non-limiting and non-exhaustive aspects of the present disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise indicated.

1 illustrates a head-mounted display (HMD), according to aspects of the present disclosure; FIG. 1 illustrates an exemplary ultrasonic polishing system, according to aspects of the present disclosure; FIG. FIG. 4 illustrates another exemplary ultrasonic polishing system, according to aspects of the present disclosure; FIG. 3 illustrates a polishing path of a polishing ball, according to aspects of the present disclosure; 4A-4D illustrate various stroke paths, contact areas and corresponding polishing areas of a polishing ball, in accordance with aspects of the present disclosure; 1 illustrates an exemplary computing device for use with an ultrasonic polishing system, according to aspects of the present disclosure; FIG. 4 is a flow diagram illustrating an exemplary process for ultrasonic sub-caliber polishing of optical elements, according to aspects of the present disclosure;

Various aspects and embodiments are disclosed in the following description and related drawings to illustrate specific examples for ultrasonic sub-caliber polishing of optical elements. Alternative aspects and embodiments will become apparent to those of ordinary skill in the art upon reading this disclosure. and may be constructed and implemented without departing from the scope of the claims. Additionally, well-known elements may not be described in detail or may be omitted so as not to obscure the relevant details of the aspects and embodiments disclosed herein.

FIG. 1 shows an HMD 100, according to aspects of the present disclosure. The illustrated example of HMD 100 is shown to include vision structure 140 , top fixation structure 141 , side fixation structure 142 , back fixation structure 143 , and front rigid body 144 . In some examples, HMD 100 is configured to be worn on the head of a user of HMD 100, where top fixation structure 141, side fixation structure 142 and/or back fixation structure 143 secure HMD 100. A fabric strap including elastic and one or more rigid structures (eg, plastic) may be included to secure to the user's head. HMD 100 may optionally include one or more earphones 120 that direct sound to one or both ears of the HMD 100 user.

The illustrated example of HMD 100 also includes an interface film 118 that contacts the face of the user of HMD 100, where interface film 118 is designed to block at least some ambient light from reaching the eyes of the user of HMD 100. function.

Exemplary HMD 100 may also include a chassis (chassis and hardware not explicitly shown in FIG. 1) that supports the hardware of visual structure 140 of HMD 100 . The hardware of visual structure 140 includes any of processing logic, wired and/or wireless data interfaces for transmitting and receiving data, graphics processors, and one or more memories for storing data and computer-executable instructions. may contain. In one example, vision structure 140 may be configured to receive wired power and/or may be configured to be powered by one or more batteries. Additionally, visual structure 140 may be configured to receive wired and/or wireless data, including video data.

Visual structure 140 may include a display system having one or more electronic displays that direct light to one or both eyes of a user of HMD 100 . The display system may include one or more of an LCD, an organic light emitting diode (OLED) display, or a micro LED display that emits light (eg, content, images, video, etc.) to a user of HMD 100.

In some examples, sensor 145 may be included in vision structure 140 . In some aspects, sensor 145 is a camera that captures images of the eyes of the user of HMD 100 for eye-tracking operations. In another aspect, the sensors 145 are Simultaneous Localization and Mapping (SLAM) sensors such as optical sensors, range finders, lidar sensors, sonar sensors, etc. that map the environment surrounding the user and/or the HMD 100 .

In some aspects, sensor 145 may include one or more small diameter optical elements such as lenses, polarizers, waveguides, reflectors, waveplates, and the like. In some aspects, a "small diameter" optical element refers to an optical element having a diameter (eg, aperture) of 3 millimeters or less. As noted above, as the requirements and accuracies for various systems of HMDs (e.g., eye-tracking or SLAM systems) increase, so does the accuracy required in manufacturing various small-diameter optical elements. .

Conventional optical element manufacturing typically begins with producing a rough shape of the optical element by diamond turning, grinding a blank, or forming the optical element in a mold. Thereafter, the optical element or its mold may be polished to its final form to achieve the desired shape and/or surface finish. In one example, polishing may be used to remove "high spots" on the optical surface. Conventional polishing techniques include utilizing a rotating pad or spinning wheel applied to the optical surface. However, for small diameter optical elements (eg, lenses with apertures less than 3 mm), it is difficult to achieve the desired accuracy using a rotating pad or spinning wheel.

Accordingly, aspects of the present disclosure are directed to sub-aperture polishing of optical surfaces, such as the surfaces of molds used to form various optical elements, and/or the surfaces of the optical elements themselves. In some aspects, high frequency (eg, ultrasonic (>20 kHz)) actuators are utilized for sub-caliber polishing of various optical elements. For example, as described below, a high frequency actuator may be configured to vibrate a polishing arm that includes a polishing ball attached to the end of a horn. Polishing the optical element, according to aspects described herein, may provide a polished area less than 10 microns in diameter.

FIG. 2 illustrates an ultrasonic polishing system, according to aspects of the present disclosure. The illustrated example of an ultrasonic polishing system 200 is shown to include a housing 202 , an ultrasonic actuator 204 and a polishing arm 206 . An exemplary polishing arm 206 is shown including a horn 208 and a polishing ball 210 . FIG. 2 also shows optical elements 212A and 212B. As shown in FIG. 2, optical element 212A is shown as a lens having optical surface 205A and aperture 213A, while optical element 212B is shown as a mold having surface 205B and aperture 213B.

An ultrasonic actuator 204 is shown contained within housing 202 and is configured to generate ultrasonic vibrations. In one example, the ultrasonic vibration frequency is greater than 20 kHz. In another example, the ultrasonic vibration frequency is in the range of 20 kHz to 40 kHz. In some implementations, the ultrasonic actuator 204 includes a magnetostrictive actuator. A magnetostrictive actuator may comprise a ferromagnetic material that produces ultrasonic vibrations in response to a magnetic field applied to the ferromagnetic material. In another implementation, ultrasonic actuator 204 includes a piezoelectric actuator. A piezoelectric actuator may comprise a solid material (eg, crystalline, ceramic, etc.) that produces ultrasonic vibrations in response to an electric field applied to the solid material.

As shown in FIG. 2, the polishing arm is coupled to the housing to receive ultrasonic vibrations generated by ultrasonic actuator 204 . In particular, proximal end 207 of horn 208 is coupled to ultrasonic actuator 204 to receive ultrasonic vibrations. During operation, horn 208 is configured to propagate ultrasonic vibrations from proximal end 207 to distal end 209 of horn 208 . In some examples, horn 208 may be made of a metal such as a stainless steel alloy. Further, although FIG. 2 shows horn 208 as having a curved shape, in other implementations horn 208 may have various shapes, such as a straight shape or a shape with multiple curves. .

Abrasive ball 210 is attached to distal end 209 of horn 208 . In some examples, polishing ball 210 is attached to distal end 209 of horn 208 by glue, epoxy, or other adhesive. In some examples, polishing ball 210 is soldered to distal end 209 . In yet another example, polishing ball 210 may include a threaded cavity that secures it to distal end 209 .

Abrasive balls 210 may be made of various materials such as sapphire, ceramics or polymers. As shown in FIG. 2, polishing ball 210 may have a spherical shape. In some examples, polishing ball 210 may have a diameter that is 3 millimeters or less. In one embodiment, polishing ball 210 has a diameter within the range of 0.5 millimeters to 3 millimeters.

During operation, polishing ball 210 is configured to vibrate in response to ultrasonic vibrations. As shown in FIG. 2, polishing balls 210 are arranged to provide lateral vibrations 211 (ie, along the xy plane) in response to ultrasonic vibrations propagated to distal end 209 of horn 208. is configured to In some examples, polishing arm 206 , including horn 208 and polishing ball 210 , has a natural frequency that matches the frequency of ultrasonic vibrations generated by ultrasonic actuator 204 . In some embodiments, the combined mass of horn 208 and polishing ball 210 is configured to provide a natural frequency of polishing arm 206 that matches the frequency of the ultrasonic vibrations. In another example, the frequency of the ultrasonic vibrations generated by ultrasonic actuator 204 is tuned to match the natural frequency of polishing arm 206 .

As described in more detail below with reference to FIGS. 4 and 5, the polishing ball 210 itself is configured to provide a polishing area on the surface of the optical element that is smaller than the aperture of the optical element. For example, as noted above, optical element 212A is shown in FIG. 2 as a lens having aperture 213A. Thus, polishing ball 210 may be applied to surface 205A to provide a polishing area smaller than aperture 213A. In some examples, optical element 212A may be glass or polymer. As another example, optical element 212B is shown in FIG. 2 as a mold used to form various small diameter optics such as lenses. Optical element 212B is shown to include aperture (ie, diameter) 213B. Thus, polishing ball 210 may be applied to surface 205B to provide a polishing area that is smaller than aperture 213B. In some examples, apertures 213A/213B are 3 millimeters or less and the polishing area provided by polishing ball 210 has a diameter of 10 micrometers or less.

FIG. 3 shows an ultrasonic polishing system 300, according to aspects of the present disclosure. The illustrated example of an ultrasonic polishing system 300 is shown to include a computer numerically controlled (CNC) positioner 302, an ultrasonic actuator 304, a polishing arm 306, a computing device 314, and an interferometer 316. It is Polishing arm 306 is shown to include horn 308 and polishing ball 310 . Optical element 312 is also shown in FIG.

Ultrasonic actuator 304, polishing arm 306, horn 308 and polishing ball 310 are configured similarly to corresponding components 204, 206, 208 and 210 described above with reference to FIG. As shown in FIG. 3, ultrasonic actuator 304 and polishing arm 306 may be attached to or incorporated into CNC positioner 302 to change the position of polishing ball 310 relative to surface 311 of optical element 312 .

In one aspect, CNC positioner 302 is a powered steerable platform controlled by one or more control signals 315 generated by computing device 314 . In some examples, CNC positioner 302 is a CNC mill configured to move polishing arm 306 and/or optical element 312 to different locations and/or depths. In some embodiments, the CNC positioner 302 includes one or more direct drive stepper motors or servo motors to move the polishing arm 306 along multiple axes (eg, X, Y and Z axes). , and thus may provide high precision movement of the polishing ball 310 .

In some aspects, computing device 314 moves polishing ball 310 over optical element 312 by generating control signals 315 that guide CNC positioner 302 to change the position of polishing ball 310 and/or optical element 312 . It is configured to guide along a polishing path on surface 311 . By way of example, FIG. 4 shows a plan view of a polishing path 404 of polishing ball 310 along surface 311 of optical element 312, according to aspects of the present disclosure. In some aspects, CNC positioner 302 is configured to guide polishing ball 310 along polishing path 404 to polish the entire surface 311 in a continuous fashion. Accordingly, FIG. 4 shows polishing path 404 as having a spiral pattern. However, various other patterns such as a raster or quasi-random meander for polishing path 404 may be utilized to polish surface 311 .

FIG. 4 illustrates various positions (eg, position 406A and position 406B) of polishing ball 310 as CNC positioner 302 guides polishing ball 310 along polishing path 404. FIG. As noted above, the polishing ball 310 may vibrate laterally in response to ultrasonic vibrations generated by an ultrasonic actuator. Thus, during operation, polishing ball 310 may vibrate on travel path 408 (eg, due to lateral vibration) as the polishing ball is guided along polishing path 404 . When in position 406A, polishing ball 310 may vibrate along stroke path 408 to provide polishing area 410A. As noted above, abrasive region 410A may have a diameter of 10 microns or less.

In some examples, CNC positioner 302 is guided by computing device 314 to change one or more parameters such that polishing balls 310 are guided along polishing path 404 by one or more The amount of material removed from surface 311 may be adjusted at multiple locations. In one aspect, CNC positioner 302 may adjust the speed at which polishing balls 310 are guided along polishing path 404 . As an example, CNC positioner 302 may move polishing ball 310 at first velocity 412A such that polishing ball 310 passes position 406A. However, the velocity may be adjusted to a second velocity 412B such that polishing ball 310 passes position 406B. In one example, CNC positioner 302 may increase the amount of material removed from surface 311 by decreasing the velocity of polishing balls 310 to increase the time that polishing balls 310 remain over an area of surface 311 . good.

Referring now to FIG. 3, CNC positioner 302 may also be configured to vary load 322 applied by grinding ball 310 to surface 311 . In some aspects, load 322 is a downward mechanical force applied to polishing arm 306 by CNC positioner 302 . In some examples, CNC positioner 302 may adjust the size of the polishing region (eg, polishing region 410A and/or 410B of FIG. 4) by adjusting load 322 in response to control signal 315. . In one aspect, CNC positioner 302 may increase the size of the polishing area provided by polishing ball 310 by increasing load 322 . In another aspect, CNC positioner 302 may increase the amount of material removed from surface 311 by increasing load 322 at one or more locations along the polishing path.

As described above, computing device 314 generates control signals 315 to guide CNC positioner 302 to change the position of polishing balls 310 along a polishing path (eg, polishing path 404 in FIG. 4). is configured to Additionally, computing device 314 may be removed by polishing ball 310 at various locations along polishing path 404 by varying one or more parameters (eg, speed and/or force) of CNC positioner 302 . It may be configured to adjust the amount of material to be applied. In some examples, computing device 314 is configured to vary one or more parameters based on the surface error map of optical element 312 . In one aspect, the surface error map represents the current surface 311 of the optical element 312 and can identify one or more high and/or low points on the surface 311 . In another aspect, the surface error map may identify one or more locations on surface 311 that deviate from the desired shape of optical element 312 .

Accordingly, in some examples, the ultrasonic polishing system 300 may include an interferometer 316 arranged to obtain one or more surface measurements (i.e., measurements 317) of the optical element 312. good. In one aspect, interferometer 316 is configured to measure small displacements, refractive index changes, and/or surface irregularities of optical element 312 . As an example, interferometer 316 may generate a single light source 318 at various locations on optical element 312 . A single light source 318 may be split into two beams that travel different optical paths, which are then combined to produce interference. The interference may then be analyzed to generate measurements 317. FIG. In response to receiving measurements 317, computing device 314 may generate a surface error map, which is then used by computing device to generate a removal map. In some aspects, one or more control signals 315 are generated by computing device 314 based on the removal map.

As noted above, when the polishing ball (eg, polishing ball 310 of FIG. 3) is guided along the polishing path, the polishing ball may also follow the travel path (eg, due to lateral vibration). 5A-5C illustrate various stroke paths (eg, stroke paths 504A, 504B, and 504C), contact areas (eg, contact area 502), and corresponding polishing areas of a polishing ball (eg, contact area 502), according to aspects of the present disclosure. For example, polishing regions 506A, 506B and 506C) are shown.

FIG. 5A shows an exemplary contact area 502. FIG. In some aspects, contact area 502 represents the contact area between the polishing ball and the surface of the optical element. The size of the contact area 502 itself may depend on various factors such as the load applied to the polishing ball, the diameter of the polishing ball, and the material properties of the polishing ball and/or the optical element. During operation, the polishing ball may vibrate in response to ultrasonic vibrations to provide a stroke path 504A that provides an effective polishing area 506A. Abrasive region 506A may have a diameter that is less than 10 microns.

As shown in FIG. 5A, stroke path 504A is a linear stroke path that provides movement of the polishing ball along the Y-axis in response to ultrasonic vibrations. In one example, the linear stroke path is provided in response to ultrasonic vibrations generated by a piezoelectric actuator that may be included in an ultrasonic actuator (eg, ultrasonic actuator 304 of FIG. 3).

FIG. 5B shows another linear stroke path, stroke path 504B, but provides movement of the polishing ball along the X-axis. As shown, movement of the polishing ball along stroke path 504B provides effective polishing area 506B. Similar to stroke path 504A above, stroke path 504B of FIG. 5B may be generated in response to ultrasonic vibrations generated by a piezoelectric actuator.

FIG. 5C shows an exemplary elliptical travel path 504C. As shown in FIG. 5C, an elliptical travel path 504C causes the polishing ball to move elliptical in the XY plane to provide an effective polishing area 506C. In one example, elliptical travel path 504C is provided in response to ultrasonic vibrations generated by a magnetostrictive actuator that may be included in an ultrasonic actuator (eg, ultrasonic actuator 304 of FIG. 3).

FIG. 6 illustrates an exemplary computing device 602 for use with an ultrasonic polishing system, according to aspects of the disclosure. The illustrated example of computing device 602 is shown to include communication interface 604 , one or more processors 606 , hardware 608 , and memory 610 . Computing device 602 is one possible implementation of computing device 314 in FIG.

Communication interface 604 may include wireless and/or wired communication components that allow computing device 602 to send data to and receive data from other devices, such as CNC positioner 302 in FIG. make it possible. Hardware 608 may include additional hardware interface, data communication, or data storage hardware. For example, a hardware interface may include data output devices (eg, electronic displays, audio speakers) as well as one or more data input devices.

Memory 610 may be implemented using computer-readable media such as computer storage media. In some aspects computer-readable media may include volatile and/or nonvolatile, removable and/or non-removable media that contain computer readable instructions, data structures, program modules, or any other method or technology for storing information such as data. Computer readable media may include RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disc (DVD), high definition multimedia/data storage discs, or other optical storage devices, magnetic cassettes, It includes, but is not limited to, magnetic tape, magnetic disk storage or other magnetic storage, or any other non-transmission medium that can be used to store information for access by a computing device.

Processor 606 and memory 610 of computing device 602 may implement surface error map and removal module 612 and CNC control module 614 . Surface error map and removal module 612 and CNC control module 614 may include routines, program instructions, objects, and/or data structures that perform particular tasks or implement particular abstract data types. Memory 610 may also include a data store (not shown) used by surface error map and removal module 612 and/or CNC control module 614 .

Surface error map and removal module 612 may be configured to generate a surface error map and removal map for an optical element (eg, optical element 312 of FIG. 3). In one example, surface error map and removal module 612 generates a surface error map in response to one or more measurements obtained from an interferometer (eg, measurements 317 produced by interferometer 316 in FIG. 3). may be generated. In other examples, the surface error map and removal module 612 may generate the surface error map based on one or more other optical measurement techniques such as direct surface profiling (eg, with a profilometer). .

CNC control module 614 operates a CNC positioner (eg, CNC positioner 302 in FIG. 3) to change the position of the polishing arm (eg, polishing arm 306) relative to the surface of the optical element (eg, surface 311 of optical element 312). It is configured to generate one or more inducing control signals (eg, control signal 315 of FIG. 3). In some examples, CNC control module 614 is configured to generate control signals based on the surface error map and the removal map generated by removal module 612 . For example, the removal map may identify one or more areas on surface 311 of optical element 312 that are high areas or areas where additional material needs to be removed. Accordingly, the CNC control module 614 directs the polishing ball along the polishing path to increase the amount of material removed from the surface of the optical element when the polishing ball is in a position corresponding to the identified elevated area of the optical element. A control signal may be generated that alters the load and/or velocity of the polishing ball as it is guided along.

FIG. 7 is a flow diagram illustrating an exemplary process 700 for ultrasonic sub-caliber polishing of optical elements, according to aspects of the present disclosure. Process 700 is one example process that may be performed by computing device 314 in FIG. 3 and/or computing device 602 in FIG.

At process block 702, an ultrasonic actuator (eg, ultrasonic actuator 304) is enabled to generate ultrasonic vibrations. In one aspect, CNC control module 614 may enable ultrasonic actuators by generating one or more control signals 315 via communication interface 604 . Next, at process block 704, the CNC control module 614 issues a control signal (e.g., a , control signals 315).

As noted above, in some examples, the CNC control module 614 may generate control signals that vary parameters such as load and/or speed of the polishing arm based on the surface error map of the optical element. Accordingly, process 700 may further include surface error map and removal module 612, which receives one or more surface measurements (e.g., measurement 317 of FIG. 3), and based on the surface measurements, Generate a surface error map of the optical element. The CNC control module 614 then generates one or more additional control signals to vary the load and/or velocity at various locations of the polishing ball along the optical path to remove from the surface of the optical element. You may adjust the amount of the ingredients you use.

Embodiments of the present invention may include, or be implemented in connection with, the creation of artificial reality systems. Artificial reality is a form of reality that has been conditioned in some way before presentation to the user, such as virtual reality (VR), augmented reality (AR), mixed reality (MR), hybrid reality. , or any combination and/or derivation thereof. Artificial reality content may include fully generated content or generated content combined with captured (eg, real-world) content. Artificial reality content may include video, audio, haptic feedback, or some combination thereof, any of which may be single channel or multiple channels (stereo video that produces a three-dimensional effect to the viewer). etc.). Further, in some embodiments, applications used, for example, to create content within artificial reality and/or otherwise used within artificial reality (e.g., used to perform activities) , products, accessories, services, or some combination thereof. Artificial reality systems that provide artificial reality content may be implemented on a variety of platforms, including head-mounted displays (HMDs) connected to a host computer system, stand-alone HMDs, mobile devices, or computing devices. , or any other hardware platform capable of providing artificial reality content to one or more viewers.

The above description of illustrative embodiments of the invention, including what is described in the Abstract, are not intended to be exhaustive or to limit the invention to the precise forms disclosed. not intended. Although specific embodiments of the invention and examples thereof have been described herein for purposes of illustration, those skilled in the art will appreciate that various modifications are possible within the scope of the invention. will recognize.

These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the particular embodiments disclosed herein. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.

Claims (15)

An ultrasonic polishing system for polishing an optical element, comprising:
an ultrasonic actuator configured to generate ultrasonic vibrations;
a polishing arm coupled to the ultrasonic actuator, the polishing arm comprising:
a horn having a proximal end coupled to receive the ultrasonic vibrations, the horn being configured to propagate the ultrasonic vibrations from the proximal end to a distal end of the horn; a horn;
a polishing ball attached to the distal end of the horn configured to vibrate in response to the ultrasonic vibrations to polish a surface of the optical element, the polishing ball being smaller than the aperture of the optical element; a polishing ball configured to provide a polishing area on the surface of the optical element;
an ultrasonic polishing system. The polishing area has a diameter of 10 micrometers or less, and/or preferably the aperture of the optical element is 3 millimeters or less, and/or preferably the polishing ball has a spherical shape. The ultrasonic polishing system of claim 1. 3. The ultrasonic polishing system of claim 1 or 2, wherein the polishing balls comprise sapphire. 4. The ultrasonic polishing system of any one of claims 1-3, wherein the polishing arm has a natural frequency that matches the frequency of the ultrasonic vibrations. The ultrasonic polishing system according to any one of claims 1 to 4, wherein the ultrasonic vibration has a frequency of 20 kHz or more. 6. The ultrasonic polishing system according to any one of claims 1 to 5, wherein the ultrasonic vibration has a frequency of 20 kHz to 40 kHz. 7. The ultrasonic polishing of any one of claims 1-6, further comprising a computer numerically controlled (CNC) positioner coupled to the polishing arm to change the position of the polishing ball relative to the surface of the optical element. system. further comprising a computing device,
The computing device is
at least one processor;
and at least one memory coupled to the at least one processor, wherein the at least one memory stores instructions, the instructions being executed by the at least one processor to:
8. The superstructure of claim 7, directing the computing device to generate one or more control signals that direct the CNC positioner to change the position of the polishing ball relative to the surface of the optical element. Sonic polishing system. The instructions for generating the one or more control signals that direct the CNC positioner to change the position of the polishing ball guide the polishing ball along a polishing path on the surface of the optical element. and preferably said instructions for guiding said polishing ball along said polishing path determine the amount of material removed from said surface of said optical element at one or more locations along said polishing path. and/or preferably comprising instructions for varying at least one of (a) the load applied to the polishing arm, or (b) the speed of the polishing ball along the polishing path, to adjust ,
Further comprising an interferometer arranged to obtain one or more surface measurements of the optical element, the at least one memory generating a surface error map of the optical element based on the surface measurements. 9. The ultrasonic polishing system of claim 8, further comprising instructions for directing the computing device to do so, wherein the instructions to change the load or speed are responsive to the surface error map. The ultrasonic actuator includes a magnetostrictive actuator, and the abrasive ball vibrates along an elliptical travel path on the surface of the optical element in response to the ultrasonic vibrations generated by the magnetostrictive actuator. 10. The ultrasonic polishing system of any one of claims 1-9 configured. The ultrasonic actuator includes a piezoelectric actuator such that the polishing ball vibrates along a linear travel path on the surface of the optical element in response to the ultrasonic vibrations generated by the piezoelectric actuator. 11. The ultrasonic polishing system of any one of claims 1-10 configured. A method for ultrasonic sub-aperture polishing of an optical element comprising:
enabling an ultrasonic actuator to generate ultrasonic vibrations;
generating one or more control signals to guide a computer numerically controlled (CNC) positioner to change the position of a polishing arm relative to the surface of the optical element, the polishing arm comprising:
a horn having a proximal end coupled to receive the ultrasonic vibrations generated by the ultrasonic actuator, the horn transmitting the ultrasonic vibrations from the proximal end to the distal end of the horn; a horn configured to propagate;
A polishing ball attached to the distal end of the horn and configured to vibrate in response to the ultrasonic vibrations to polish the surface of the optical element, the polishing ball being smaller than the aperture of the optical element. a polishing ball configured to provide a polishing area on the surface of the optical element;
A method, including changing the position of the polishing ball includes guiding the polishing ball along a polishing path on the surface of the optical element, the method comprising:
(a) a load applied to the polishing arm; or (b) the polishing path to adjust the amount of material removed from the surface of the optical element at one or more locations along the polishing path. and generating one or more additional control signals to induce the CNC positioner to vary at least one of the velocity of the polishing ball along the
receiving one or more surface measurements of the optical element;
generating a surface error map of the optical element based on the surface measurements, wherein varying the load or velocity produces a surface error map of the optical element responsive to the surface error map. generating;
13. The method of claim 12, further comprising: enabling an ultrasonic actuator to generate ultrasonic vibrations;
generating one or more control signals to guide a computer numerically controlled (CNC) positioner to change the position of the polishing arm relative to the surface of the optical element;
An optical element polished by a method comprising:
a horn having a proximal end coupled to receive the ultrasonic vibrations generated by the ultrasonic actuator, the horn transmitting the ultrasonic vibrations from the proximal end to the distal end of the horn; a horn configured to propagate;
A polishing ball attached to the distal end of the horn and configured to vibrate in response to the ultrasonic vibrations to polish the surface of the optical element, the polishing ball being smaller than the aperture of the optical element. a polishing ball configured to provide a polishing area on the surface of the optical element;
optical elements, including receiving one or more surface measurements of the optical element;
generating a surface error map of the optical element based on the surface measurements;
(a) a load applied to the polishing arm, or (b), to adjust the amount of material removed from the surface of the optical element at one or more locations of the polishing arm along the polishing path; generating one or more additional control signals in response to the surface error map to guide the CNC positioner to change at least one of: velocity of the polishing ball along the polishing path; ,
15. An optical element polished by the method of claim 14, further comprising:

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