US-12627066-B2 - Dielectric encapsulated metal lens

Abstract

A dielectric encapsulated metal lens includes a planar conductive plate with a first surface and a second surface, wherein the first surface is parallel to the second surface; a plurality of openings from the first surface through the planar conductive plate to the second surface, wherein a longitudinal axis of each opening is perpendicular to the first surface and the second surface, wherein a size of each opening is a function of a position of said each opening on the planar conductive plate; and a dielectric material encapsulating the planar conductive plate and filing the plurality of openings, where the dielectric material forms a top surface and a bottom surface for the metal lens to reduce reflected energy.

Inventors

• David D. Crouch
• Hooman Kazemi

Assignees

• RAYTHEON COMPANY

Dates

Publication Date

20260512

Application Date

20230207

Claims (20)

1. 1 . A dielectric encapsulated metal lens comprising: a planar conductive plate with a first surface and a second surface, wherein the planar conductive plate comprises a dielectric material plated with a conductor, and wherein the first surface is parallel to the second surface; a plurality of openings from the first surface through the planar conductive plate to the second surface, wherein a longitudinal axis of each opening is perpendicular to the first surface and the second surface, wherein a size of each opening is a function of a position of the opening on the planar conductive plate; a dielectric resin encapsulating the planar conductive plate and filling the plurality of openings, wherein the dielectric resin forms a top surface and a bottom surface for the dielectric encapsulated metal lens to reduce reflected energy; a first impedance-matching layer covering the top surface; and a second impedance-matching layer covering the bottom surface.
2. 2 . The dielectric encapsulated metal lens of claim 1 , wherein the openings are arranged in the planar conductive plate in an equilateral triangular pattern.
3. 3 . The dielectric encapsulated metal lens of claim 1 , wherein the openings are arranged in the planar conductive plate in a rectangular, square, or circular pattern.
4. 4 . The dielectric encapsulated metal lens of claim 1 , wherein a shape of the plurality of openings is circular.
5. 5 . The dielectric encapsulated metal lens of claim 1 , wherein a shape of the plurality of openings is hexagonal.
6. 6 . The dielectric encapsulated metal lens of claim 1 , wherein the dielectric resin is a low-loss resin.
7. 7 . The dielectric encapsulated metal lens of claim 1 , wherein the dielectric material is injection-molded plastic.
8. 8 . The dielectric encapsulated metal lens of claim 1 , wherein the conductor comprises at least one of copper and gold.
9. 9 . The dielectric encapsulated metal lens of claim 1 , wherein the size of each opening is selected such that an insertion phase collectively imposed by the openings on an incident wave causes the incident wave to pass through the first surface and the planar conductive plate, exit from the second surface, and focus on a predetermined distance from the second surface.
10. 10 . A method of fabricating a dielectric encapsulated metal lens, the method comprising: providing a mold filled with a dielectric liquid resin, the mold including a plurality of spacers in or integral to the mold; providing a metal lens comprising: a planar conductive plate with a first surface and a second surface, wherein the planar conductive plate comprises a dielectric material plated with a conductor, and wherein the first surface is parallel to the second surface; and a plurality of openings from the first surface through the planar conductive plate to the second surface, wherein a longitudinal axis of each opening is perpendicular to the first surface and the second surface, wherein a size of each opening is a function of a position of the opening on the planar conductive plate; inserting the metal lens in the mold filled with the dielectric liquid resin to be situated on the spacers to form a dielectric bottom surface, the metal lens being encapsulated by the dielectric liquid resin and the plurality of openings being filled with the dielectric liquid resin; forming a top dielectric surface on top of the metal lens; curing the dielectric liquid resin encapsulating the metal lens and removing the cured dielectric resin from the mold; machining the cured dielectric resin to reduce a thickness of the top dielectric surface to form the dielectric encapsulated metal lens; covering the top dielectric surface with a first impedance-matching layer; and covering the bottom dielectric surface with a second impedance-matching layer; wherein the top dielectric surface and the bottom dielectric surface of the dielectric encapsulated metal lens reduce reflected energy.
11. 11 . The method of claim 10 , wherein the openings are formed by a high-power laser or computer numerical control (CNC) machine tool to drill the openings.
12. 12 . The method of claim 10 , wherein the openings are formed by additive manufacturing.
13. 13 . The method of claim 10 , wherein the dielectric material is injection-molded plastic, and the openings are formed by the injection-molding of the plastic.
14. 14 . The method of claim 10 , wherein the conductor comprises at least one of copper and gold.
15. 15 . The method of claim 10 , wherein the openings are arranged in an equilateral triangular, rectangular, square, or circular pattern.
16. 16 . The method of claim 10 , wherein a shape of the plurality of openings is circular.
17. 17 . The method of claim 10 , wherein a shape of the plurality of openings is hexagonal.
18. 18 . The method of claim 10 , wherein the size of each opening is selected such that an insertion phase collectively imposed by the openings on an incident wave causes the incident wave to pass through the first surface and the planar conductive plate, exit from the second surface, and focus on a predetermined distance from the second surface.
19. 19 . The dielectric encapsulated metal lens of claim 1 , wherein the dielectric resin is cyanate-ester.
20. 20 . The method of claim 10 , wherein the dielectric liquid resin is cyanate-ester.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This patent application is a Continuation-In-Part and claims the benefits of U.S. patent application Ser. No. 17/524,644, filed on Nov. 11, 2021 and entitled “Planar Metal Fresnel Millimeter-Wave Lens,” the entire content of which is hereby expressly incorporated by reference. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention disclosure is related to a government contract number HR0011-22-C-0035. The U.S. Government has certain rights to this invention. FIELD OF THE INVENTION The disclosure relates generally to metal lenses and more specifically to a dielectric encapsulated metal lens. BACKGROUND Millimeter waves are electromagnetic waves having wavelengths between 1 and 10 millimeters and frequencies between 30 and 300 gigahertz (GHz). Millimeter-waves propagate primarily by line-of-sight paths and are being increasingly used in a variety of applications, such as, scientific research (e.g., radio astronomy and remote sensing), telecommunications (including the new generation of 5G cell phone networks), collision avoidance, military/weapon systems, security screening, plasma heating for inertial confinement fusion, material processing, medicine, law enforcement, and the like. In all these applications, there is a need for quasi-optical beam processing elements (such as lenses) that are capable of high average power operation. Conventional lenses, whether millimeter or optical lens, operate by varying the physical path length over which the incident radiation must traverse to pass through the lens. Existing metal lens designs fall generally into two classes. Parallel-plate metal lenses consist of a number of parallel metal plates that act like waveguides for incident radiation polarized parallel to the plates. The depth of the plates is varied as a function of position relative to the center of the lens to impart the desired shape to incident wave fronts. Perforated plate lenses consist of a uniform array of circular holes/openings; one or both plate surfaces are shaped as a means of varying path length with position. A lens having high-power capability is needed to process high-intensity millimeter beams. However, dielectric lenses have low thermal conductance. Likewise, existing metal lenses require non-planar surfaces, and have added weight and higher insertion loss. Also, the thermal conductance of parallel plate metal lenses is inhibited by the thinness of the plates and the fact that heat is conducted along one direction only. Accordingly, there is a need for low-loss quasi-optical beam processing elements (such as lenses) capable of high average power operation. SUMMARY The present disclosure is directed to dielectric encapsulated metal lenses. In some embodiments, a dielectric encapsulated metal lens includes a planar conductive plate with a first surface and a second surface, wherein the first surface is parallel to the second surface; a plurality of openings from the first surface through the planar conductive plate to the second surface, wherein a longitudinal axis of each opening is perpendicular to the first surface and the second surface, wherein a size of each opening is a function of a position of said each opening on the planar conductive plate; and a dielectric material encapsulating the planar conductive plate and filling the plurality of openings, wherein the dielectric material forms a top surface and a bottom surface for the metal lens to reduce reflected energy. In some embodiments, a method of fabricating a dielectric encapsulated metal lens, includes: providing a mold filled with dielectric liquid resin; a plurality of spacers in or integral to the mold or built into the mold; providing a planar metal plate including a plurality of openings; inserting the planar metal perforated plate into the mold filled with dielectric liquid resin to be situated on the spacers to form a dielectric bottom surface for the planar metal plate, the planar metal plate being encapsulated by the dielectric liquid resin and the plurality of openings being filled with the dielectric liquid resin; forming a top dielectric surface on top of the planar metal plate; curing and removing the encapsulated planar metal plate from the mold; and machining to reduce the thickness of the top dielectric surface to form the dielectric encapsulated metal lens. BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the disclosed invention, and many of the attendant features and aspects thereof, will become more readily apparent as the disclosed invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate like components. FIG. 1A depicts a top view, FIG. 1B shows a side view and FIG. 1C illustrates a cutaway perspective view of a planar metal millimeter-wave lens, according to some embodiments of the disclosure. FIG. 2 illustrates sc