# US 11,029,511 B2 · Low wavefront error piezoelectrically actuated optical element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,511 B2 - Document ID: US11029511B2 - Status: Granted - Kind: B2 - Application number: 16/487,763 - Filed: 2018-02-27 - Published: 2020-08-06 - Granted: 2021-06-08 - Earliest claimed: 2017-02-27 - Assignees: poLight ASA - Applicants: Polight ASA - Inventors: Vladimir Kartashov; Pierre Craen - Web page: https://patentgrep.com/patent/US11029511B2 ## CPC - G02B 26/08: for controlling the direction of light (in light guides G02B6/35) - G02B 26/0858: {the reflecting means being moved or deformed by piezoelectric means} - G02B 3/14: of variable focal length - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract There is presented an optical element (100, 500, 600, 700) comprising a support structure (101, 501) with a sidewall (112, 512), a bendable cover member (102, 502, 702) attached to the sidewall (112, 512), one or more piezoelectric actuators (103, 104, 105) arranged for shaping said bendable cover member (102, 502, 702) into a desired shape, wherein said optical element (100, 500, 600, 700) comprises an optically active area (111, 511) with an optical axis (110, 510), wherein an outer edge (215A-E) of the one or more piezoelectric actuators (103, 104, 105) as observed in a direction being parallel with the optical axis (110, 510) defines a first line, and an inner edge (109) of the support structure (101, 501) at the interface between the support structure (101, 501) and the bendable cover member (102, 502, 702) as observed in the direction being parallel with the optical axis (110, 510) defines a second line, wherein the first line and the second line as observed in the direction being parallel with the optical axis (110, 510) cross each other in two or more positions and/or are parallel and coincident in one or more positions. ## Claims ### Claim 1 An optical element comprising: a support structure having a sidewall, a bendable cover member attached to the sidewall, and a piezoelectric actuator configured to shape said bendable cover member into a predetermined shape, wherein the piezoelectric actuator comprises a piezoelectric material and electrode layers above and/or below the piezoelectric material, wherein the optical element further comprises: a. a bottom electrode, b. a piezoelectric material in the form of a piezoelectrically active layer, and c. a top electrode, wherein the position of the piezoelectric actuator, as observed in a direction being parallel with the optical axis, is given by positions, wherein there is an overlap between all of the bottom electrode, the piezoelectrically active layer and the top electrode, wherein said optical element comprises an optically active area with an optical axis, wherein the piezoelectric actuator forms a closed line, which completely encloses the optical axis, and an outer edge of the piezoelectric actuator as observed in a direction being parallel with the optical axis defines a first line, wherein the outer edge is a closed line corresponding to the edge of the piezoelectric actuator facing away from the optical axis, and an inner edge of the support structure at the interface between the support structure and the bendable cover member as observed in the direction being parallel with the optical axis defines a second line, and wherein the first line and the second line as observed in the direction being parallel with the optical axis cross each other in two or more positions, and/or are parallel and coincident in one or more positions. ### Claim 2 (depends on 1) The optical element according to claim 1, wherein above and below refer to a direction parallel to the optical axis where above is in a positive direction from the support structure to the cover member and where below is in a negative direction from the support structure to the cover member. ### Claim 3 (depends on 1) The optical element according to claim 1, wherein a portion of the electrode layers above and/or below the piezoelectric material, which is comprised in the piezoelectric actuator, is the portion, which is intersected by a line parallel to the optical axis, which line also intersects the piezoelectric material. ### Claim 4 (depends on 1) The optical element according to claim 1, wherein the second line defines a rectangle, with rounded corners. ### Claim 5 (depends on 1) The optical element according to claim 1, wherein the second line defines a square with rounded corners. ### Claim 6 (depends on 1) The optical element according to claim 1, wherein the optical element is a refractive lens comprising: at least one deformable transparent lens body surrounded by the sidewall of the support structure, wherein the bendable cover member is a bendable transparent cover member which is attached to a surface of said at least one deformable transparent lens body. ### Claim 7 (depends on 1) The optical element according to claim 1, wherein the optical element is a reflective element, and wherein the bendable cover member is reflective on the side facing away from the support structure and/or on the side facing the support structure. ### Claim 8 (depends on 1) The optical element according to claim 1, wherein a total wavefront error (WFERMS) is equal to or less than 60 nm, throughout a range of 40 volts, applied to the piezoelectric actuator. ### Claim 9 (depends on 1) The optical element according to claim 1, wherein a total wavefront error (WFERMS) is equal to or less than 60 nm, throughout a range of 5 diopters. ### Claim 10 (depends on 1) The optical element according to claim 1, wherein: a maximum total wavefront error (WFERMS) throughout a range of 40 volts, applied to the piezoelectric actuator for a corresponding optical element where the first and second lines do not cross or are parallel and coincident at one or more positions, is at least 10% larger than a maximum total wavefront error (WFERMS) throughout a range of 40 volts, applied to the piezoelectric actuator for the optical element wherein the first line and the second line as observed in the direction being parallel with the optical axis cross each other at two or more positions and/or are parallel and coincident at one or more positions. ### Claim 11 (depends on 1) The optical element according to claim 1, wherein an optically active area corresponds to an optical aperture. ### Claim 12 (depends on 1) The optical element according to claim 1, wherein the bendable cover member is glass. ### Claim 13 (depends on 8) The optical element according to claim 8, wherein the total wavefront error (WFERMS) is measured at 630 nm. ### Claim 14 (depends on 1) The optical element according to claim 1, wherein the piezoelectric actuator encircles the optical axis where an inner edge of the piezoelectric actuator towards the optical axis forms a circle with the optical axis at its center. ### Claim 15 (depends on 1) The optical element according to claim 1, wherein the first line is a square with rounded corners. ### Claim 16 (depends on 1) The optical element according to claim 1, wherein the first line is circular. ### Claim 17 (depends on 1) The optical element according to claim 1, wherein: said optical lens, has an average within a wavelength range and within the angle of incidence range, transmittance of 95% or more, a minimum transmittance over the visible range for any visible wavelength, is 94% or more, and/or wherein an average reflectivity, wherein the wavelength range is confined to any visible wavelength, over the visible range is 2.5% or less. ### Claim 18 (depends on 1) A method for manufacturing an optical element according to claim 1, said method comprising: providing the piezoelectric actuator on the bendable cover member by deposition. ### Claim 19 (depends on 1) A camera comprising the optical element according to claim 1. ### Claim 20 (depends on 1) A method of using the optical element according to claim 1 to obtain one or more images comprising acquiring one or more images with the optical element according to claim 1.