# US 12,181,346 B2 · Apparatus and method for estimating a phase retarder and method of manufacturing the phase retarder using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,181,346 B2 - Document ID: US12181346B2 - Status: Granted - Kind: B2 - Application number: 17/903,313 - Filed: 2022-09-06 - Published: 2023-04-13 - Granted: 2024-12-31 - Earliest claimed: 2021-09-29 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics and Telecommunications Research Institute - Inventors: Ki Hong Choi; Joong Ki Park; Kee Hoon Hong - Web page: https://patentgrep.com/patent/US12181346B2 ## CPC - G01J 9/00: Measuring optical phase difference (devices or arrangements for controlling the phase of light beams G02F1/01); Determining degree of coherence; Measuring optical wavelength (spectrometry G01J3/00) - G01M 11/00: Testing of optical apparatus; Testing structures by optical methods not otherwise provided for - G01N 21/95: characterised by the material or shape of the object to be examined (G01N21/89 - G01N21/91, G01N21/94 take precedence) - G01J 3/447: Polarisation spectrometry - G01J 4/04: Polarimeters using electric detection means (G01J4/02 takes precedence) - G01N 21/21: Polarisation-affecting properties (G01N21/19 takes precedence) - G01N 2021/9511: {Optical elements other than lenses, e.g. mirrors} - G01N 2021/9513: {Liquid crystal panels} - 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) - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR - 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 Disclosed herein an apparatus and method for estimating a phase retarder and method of manufacturing the phase retarder using the same. The apparatus includes: a polarization element configured to output an incident light as a linear polarization and to make the linear polarization incident onto a phase retarder to be tested; a polarization image acquisition module equipped with a plurality of polarized pixels receiving an emitting light that is output from the phase retarder, on which the linear polarization is incident, and configured to obtain a polarization image based on the emitting light that is modulated in the polarized pixels; and a processor configured to evaluate quality of the phase retarder based on uniformity of a brightness value between polarized pixels of the polarization image. The polarized pixels modulate the emitting light based on a plurality of transmission angles and detects the modulated emitting light. ## Claims ### Claim 1 An apparatus for estimating a phase retarder, the apparatus comprising: a polarization element configured to output an incident light as a linear polarization and to make the linear polarization incident onto a phase retarder to be tested; a polarization image acquisition module equipped with a plurality of polarized pixels receiving an emitting light that is output from the phase retarder, on which the linear polarization is incident, and configured to obtain a polarization image based on the emitting light that is modulated in the polarized pixels; and a processor configured to evaluate quality of the phase retarder based on uniformity of a brightness value between polarized pixels of the polarization image, wherein the polarized pixels modulate the emitting light based on a plurality of transmission angles and detects the modulated emitting light. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein each of the plurality of polarized pixels is configured to have a plurality of transmission angles. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the polarized pixels are configured to include micro pixels at each of the plurality of transmission angles. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein the micro pixels include a micro polarizer and an image sensor, which are arranged in a direction of receiving the emitting light, and wherein the micro polarizer is formed to have a transmission axis with a different transmission angle in each of the micro pixels constituting the polarized pixels. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein the polarization image acquisition module further comprises a micro lens array equipped with a micro lens that is placed in front of the micro pixels in the direction of receiving the emitting light, and wherein the micro lens array comprises a plurality of micro lenses that are arranged to cover the plurality of polarized pixels. ### Claim 6 (depends on 3) The apparatus of claim 3, wherein the processor is further configured to: obtain a minute brightness value of each the micro pixels from the polarization image, correct the minute brightness value based on a quantum efficiency of the each of the micro pixels, and obtain a brightness value of each of the polarized pixels based on the corrected minute brightness value, and wherein the quantum efficiency is a ratio between a light amount of the emitting light and an output light amount of the emitting light that has passed through the micro pixels. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein the quantum efficiency uses a relative quantum efficiency that is measured at each of the transmission angles in each wavelength of the emitting light, and wherein the relative quantum efficiency is a value that is obtained by dividing an actual quantum efficiency of each of the micro pixels by an average value of actual quantum efficiencies corresponding to transmission angles of the micro pixels that constitute the polarized pixels. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the plurality of polarized pixels are clustered into groups, and at least part of polarized pixels within the groups are configured to be expressed in different color channels. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the processor is further configured to: determine uniformity based on a standard deviation that is based on brightness values of the plurality of polarized pixels in the polarization image, and determine that the phase retarder has fair quality in response to the standard deviation being equal to or less than a permissible tolerance. ### Claim 10 A method for estimating a phase retarder by using an apparatus for estimating a phase retarder, which is equipped with a polarization element, a polarization image acquisition module having a plurality of polarized pixels, and a processor, the method comprising: outputting, by the polarization element, an incident light as a linear polarization and making the linear polarization incident onto a phase retarder to be tested; receiving, by the polarization image acquisition module, an emitting light, which is output from the phase retarder on which the linear polarization is incident, in a plurality of polarized pixels and obtaining a polarization image of the phase retarder based on the emitting light that is modulated in the polarized pixels; and evaluating, by the processor, quality of the phase retarder based on uniformity of a brightness value between polarized pixels of the polarization image, wherein the polarized pixels modulate the emitting light based on a plurality of transmission angles and detect the modulated emitting light. ### Claim 11 (depends on 10) The method of claim 10, wherein each of the plurality of polarized pixels is configured to have a plurality of transmission angles. ### Claim 12 (depends on 10) The method of claim 10, wherein the polarized pixels are configured to include micro pixels at each of the plurality of transmission angles. ### Claim 13 (depends on 12) The method of claim 12, wherein the micro pixels include a micro polarizer and an image sensor, which are arranged in a direction of receiving the emitting light, and wherein the micro polarizer is formed to have a transmission axis with a different transmission angle in each of the micro pixels constituting the polarized pixels. ### Claim 14 (depends on 13) The method of claim 13, wherein the polarization image acquisition module further comprises a micro lens array equipped with a micro lens that is placed in front of the micro pixels in the receiving direction, and wherein the micro lens array comprises a plurality of micro lenses that are arranged to cover the plurality of polarized pixels. ### Claim 15 (depends on 12) The method of claim 12, wherein the evaluating of the quality of the phase retarder further comprises: obtaining a minute brightness value of each of the micro pixels from the polarization image, correcting the minute brightness value based on a quantum efficiency of the each of the micro pixels, and obtaining a brightness value of each of the polarized pixels based on the corrected minute brightness value, and wherein the quantum efficiency is a ratio between a light amount of the emitting light and an output light amount of the emitting light that has passed through the micro pixels. ### Claim 16 (depends on 15) The method of claim 15, wherein the quantum efficiency uses a relative quantum efficiency that is measured at each of the transmission angles in each wavelength of the emitting light, and wherein the relative quantum efficiency is a value that is obtained by dividing an actual quantum efficiency of each of the micro pixels by an average value of actual quantum efficiencies corresponding to transmission angles of the micro pixels that constitute the polarized pixels. ### Claim 17 (depends on 10) The method of claim 10, wherein the plurality of polarized pixels are clustered into groups, and at least part of polarized pixels within the groups are configured to be expressed in different color channels. ### Claim 18 (depends on 10) The method of claim 10, wherein the evaluating of the phase retarder further comprises: determining uniformity based on a standard deviation that is based on brightness values of the plurality of polarized pixels in the polarization image, and determining that the phase retarder has fair quality in response to the standard deviation being equal to or less than a permissible tolerance. ### Claim 19 A method for manufacturing a phase retarder by using an apparatus for estimating a phase retarder, which is equipped with a polarization element, a polarization image acquisition module having a plurality of polarized pixels, and a processor, the method comprising: outputting, by the polarization element, an incident light as a linear polarization and making the linear polarization incident onto a phase retarder sample; receiving, by the polarization image acquisition module, an emitting light, which is output from the phase retarder sample on which the linear polarization is incident, in a plurality of polarized pixels and obtaining a polarization image of the phase retarder sample based on the emitting light that is modulated in the polarized pixels; evaluating, by the processor, quality of the phase retarder sample based on uniformity of a brightness value between polarized pixels of the polarization image; transmitting, by the processor, a fair quality message to a phase retarder manufacturing device in response to the phase retarder sample being evaluated to have fair quality, in order to apply a manufacturing processing condition of the sample in the phase retarder manufacturing device; and transmitting, by the processor, a poor quality message to the phase retarder manufacturing device in response to the phase retarder sample being evaluated to have poor quality, in order to modify the manufacturing processing condition of the sample in the phase retarder manufacturing device, wherein the polarized pixels modulate the emitting light based on a plurality of transmission angles and detect the modulated emitting light. ### Claim 20 (depends on 19) The method of claim 19, wherein each of the plurality of polarized pixels is configured to have a plurality of transmission angles.