# US 2025/0085191 A1 · 3D Refractive Index Estimation Based on Partially-Coherent Optical Diffraction Tomography (PC-ODT) and Deep Learning > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0085191 A1 - Document ID: US20250085191A1 - Status: Published application - Kind: A1 - Application number: 18/225,100 - Filed: 2023-07-21 - Published: 2025-03-13 - Earliest claimed: 2022-07-24 - Inventors: George Nehmetallah - Web page: https://patentgrep.com/patent/US20250085191A1 ## CPC - G01M 11/0228: {by measuring refractive power} - G01M 11/0207: {Details of measuring devices} - G02B 21/06: Means for illuminating specimens - G02B 21/08: Condensers - G02B 21/14: affording illumination for phase-contrast observation - G02F 1/294: {Variable focal length devices} - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS ## Abstract A system, a microscope, and a method for determining a three dimensional refractive index are provided. The system comprises an illumination system configured to generate an illumination beam to illuminate a target at a plurality of illumination angles; an optical system to direct the illumination beam to the target; a refocusing system positioned in a detection path and configured to perform stageless axial refocusing of a measurement beam, a detection system configured to capture an intensity stack for the plurality of illumination angles and during the axial refocusing; and a processor configured to generate a three dimensional refractive index of the target based on the intensity stack. The measurement beam is transmitted through the target. ## Claims ### Claim 1 A system comprising: an illumination system configured to generate an illumination beam to illuminate a target at a plurality of illumination angles; an optical system to direct the illumination beam to the target; a refocusing system positioned in a detection path and configured to perform stageless axial refocusing of a measurement beam, wherein the measurement beam is transmitted through the target; a detection system configured to capture an intensity stack for the plurality of illumination angles and during the axial refocusing; and a processor configured to generate a three dimensional refractive index of the target based on the intensity stack. ### Claim 2 (depends on 1) The system of claim 1, wherein the illumination system comprises a light emitting diode (LED) dome array and wherein the LED dome array comprises a plurality of LEDs. ### Claim 3 (depends on 2) The system of claim 2, wherein each LED of the LED dome array is individually controlled; and wherein an illumination time of each respective LED is controlled by the processor during measurement. ### Claim 4 (depends on 3) The system of claim 3, wherein two or more LEDs are simultaneously activated during measurement to increase a throughput of the system. ### Claim 5 (depends on 1) The system of claim 1, wherein the illumination beam is partially coherent. ### Claim 6 (depends on 1) The system of claim 1, wherein the optical system comprises an objective lens. ### Claim 7 (depends on 1) The system of claim 1, wherein the refocusing system comprises, a divergent offset lens and an electronically tunable lens. ### Claim 8 (depends on 7) The system of claim 7, wherein the refocusing system does not comprise moving mechanical parts. ### Claim 9 (depends on 7) The system of claim 7, wherein the refocusing system further comprises a relay lens system; and wherein the offset lens and the electronically tunable lens are positioned in the detection path at a focal plane of the relay lens system. ### Claim 10 (depends on 1) The system of claim 1, wherein the three dimensional refractive index is generated using a trained neural network model, and wherein the intensity stack is an input to the trained neural network model. ### Claim 11 (depends on 1) The system of claim 1, wherein training the neural network model comprises: generating intensity patterns through propagating illumination beams at the plurality of illumination angles through a sample and at a plurality of focus length of the refocusing system; and reconstructing the respective three dimensional refractive index using a gradient based technique. ### Claim 12 (depends on 11) The system of claim 11, wherein the intensity patterns are generated through a simulation of the system and wherein the sample is a phantom. ### Claim 13 (depends on 11) The system of claim 11, wherein the neural network model is trained using biological samples. ### Claim 14 (depends on 1) The system of claim 1, wherein the intensity stack represents a plurality of intensity images captured by the detection system for the plurality of illumination angles and for a plurality of focus length of the refocusing system. ### Claim 15 A digital microscope comprising: an illumination system configured to generate an illumination beam to illuminate a target at a plurality of illumination angles; an optical system to direct the illumination beam to the target; a refocusing system positioned in a detection path and configured to perform stageless axial refocusing of a measurement beam, wherein the measurement beam is transmitted through the target; a detection system configured to capture an intensity stack for the plurality of illumination angles and during the axial refocusing; and a processor configured to generate a three dimensional refractive index of the target based on the intensity signal. ### Claim 16 (depends on 15) The digital microscope of claim 15, wherein the refocusing system comprises a divergent offset lens and an electronically tunable lens. ### Claim 17 (depends on 16) The digital microscope of claim 16, wherein the electronically tunable lens is a tunable liquid crystal lens. ### Claim 18 (depends on 16) The digital microscope of claim 16, wherein the refocusing system does not comprise moving mechanical parts. ### Claim 19 A method for determining a three dimensional refractive index of a target, comprising illuminating the sample at a plurality of illumination angles using an partially incoherent beam; performing stageless axial refocusing of a measurement beam, wherein the measurement beam is transmitted through the target; capturing an intensity stack for the plurality of illumination angles and during the axial refocusing; and generating the three dimensional refractive index of the target using a trained neural network. ### Claim 20 (depends on 16) The method of claim 16, wherein training the neural network comprises: generating intensity patterns through propagating illumination beams at the plurality of illumination angles through a sample and at a plurality of focus length of the refocusing system; and reconstructing the respective three dimensional refractive index using a gradient based technique.