# US 10,309,833 B2 · Room-temperature quantum noise limited spectrometry and methods of the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,309,833 B2 - Document ID: US10309833B2 - Status: Granted - Kind: B2 - Application number: 15/960,350 - Filed: 2018-04-23 - Published: 2018-08-30 - Granted: 2019-06-04 - Earliest claimed: 2010-03-30 - Assignees: Lawrence Livermore National Security, LLC - Applicants: Lawrence Livermore National Security, LLC - Inventors: Charles G. Stevens; Joseph W. Tringe; Christopher T. Cunningham - Web page: https://patentgrep.com/patent/US10309833B2 ## CPC - G01J 3/453: by correlation of the amplitudes - G01J 3/10: Arrangements of light sources specially adapted for spectrometry or colorimetry - G01J 3/4338: {Frequency modulated spectrometry} - G01N 21/35: using infrared light (G01N21/39 takes precedence) - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract According to one embodiment, a method of forming a plasmonic condensing lens for room temperature quantum noise limited (QNL) infrared (IR) spectrometry includes: forming a silicon cone on a substrate; coating the silicon cone with a highly reflective material; and modifying the silicon cone using focused ion beam (FIB) modification to permit transmittance of light through the silicon cone. ## Claims ### Claim 1 A method of forming a plasmonic condensing lens for room temperature quantum noise limited (QNL) infrared (IR) spectrometry, the method comprising: forming a silicon cone on a substrate; coating the silicon cone with a highly reflective material; and modifying the silicon cone using focused ion beam (FIB) modification to permit transmittance of light through the silicon cone. ### Claim 2 (depends on 1) The method as recited in claim 1, wherein forming the silicon cone on the substrate comprises reactive ion etching. ### Claim 3 (depends on 1) The method as recited in claim 1, wherein the highly reflective material is selected from a group consisting of Au, Ag, Pt and Cu. ### Claim 4 (depends on 1) The method as recited in claim 1, wherein the substrate comprises SiO2. ### Claim 5 (depends on 1) The method as recited in claim 1, wherein modifying the silicon cone using FIB produces a silicon cone characterized by an aperture diameter approximately one-seventh ( 1/7) that of a wavelength of light that is to be detected by a detector coupled to the silicon cone. ### Claim 6 (depends on 5) The method as recited in claim 5, wherein the detector is placed in direct contact with the aperture of the silicon cone. ### Claim 7 (depends on 1) The method as recited in claim 1, wherein the silicon cone is formed to have dimensions including a length of about 10 μm, a diameter at a receiving end of about 3.5 μm, and a diameter at a transmitting end of about 0.5 μm. ### Claim 8 (depends on 1) The method as recited in claim 1, comprising installing the plasmonic condensing lens in a heterodyne detection system for detecting light, the system comprising: a first input aperture configured to receive first light from a scene input; a second input aperture configured to receive second light from a local oscillator input; a broadband local oscillator configured to provide the second light to the second input aperture; a dispersive element configured to disperse the first light and the second light; and the plasmonic condensing lens coupled to an infrared detector, wherein the plasmonic condensing lens is configured to concentrate incident light from a primary condensing lens onto the infrared detector, wherein the infrared detector is a square-law detector configured to sense a frequency difference between the first light and the second light; and wherein each area of the first and second input apertures times an input collection solid angle of the system is about a wavelength squared (about λ2). ### Claim 9 (depends on 1) The method as recited in claim 1, comprising installing the plasmonic condensing lens in a heterodyne detection system for detecting light, the system comprising: a first input aperture configured to receive first light from a scene input; a second input aperture configured to receive second light from a local oscillator input; a broadband local oscillator configured to provide the second light to the second input aperture; a dispersive element configured to disperse the first light and the second light; and the plasmonic condensing lens coupled to an infrared detector; wherein the plasmonic condensing lens is configured to concentrate incident light from a primary condensing lens onto the infrared detector; wherein the infrared detector is a square-law detector configured to sense a frequency difference between the first light and the second light; wherein the plasmonic condensing lens has a conical shape tapering inward toward the infrared detector; and wherein the conical shape has a first diameter at an end adjacent the infrared detector of less than about one-half wavelength of the incident light in Si, and wherein the conical shape has a second diameter at an end receiving the incident light from the dispersive element of approximately a diffraction limit set by the primary condensing lens. ### Claim 10 (depends on 1) The method as recited in claim 1, comprising installing the plasmonic condensing lens in a heterodyne detection system for detecting light, the system comprising: a first input aperture configured to receive first light from a scene input; a second input aperture configured to receive second light from a local oscillator input; a broadband local oscillator configured to provide the second light to the second input aperture; a dispersive element configured to disperse the first light and the second light; and the plasmonic condensing lens coupled to a detector; wherein the plasmonic condensing lens is configured to concentrate incident light from a primary condensing lens onto the detector; and wherein the detector is detector configured to sense a frequency difference between the first light and the second light.