公开(公告)号：US10527562B2

公开(公告)日：2020-01-07

申请号：US15517122

申请日：2015-10-29

Applicant: Massachusetts Institute of Technology ,  The General Hospital Corporation

Inventor： Achuta Kadambi ,  Ramesh Raskar ,  Rajiv Gupta ,  Adam Pan

IPC: A61B6/10 ,  G01N23/083 ,  G01N23/046 ,  G01T1/24 ,  G21K1/04 ,  H01J35/06 ,  H01J35/14

Abstract: For each X-ray path through a tissue, numerous trials are conducted. In each trial, X-ray photons are emitted along the path until a Geiger-mode avalanche photodiode “clicks”. A temporal average—i.e., the average amount of time elapsed before a “click” occurs—is calculated. This temporal average is, in turn, used to estimate a causal intensity of X-ray light that passes through the tissue along the path and reaches the diode. Based on the causal intensities for multiple paths, a computer generates computed tomography (CT) images or 2D digital radiographic images. The causal intensities used to create the images are estimated from temporal statistics, and not from conventional measurements of intensity at a pixel. X-ray dosage needed for imaging is dramatically reduced as follows: a “click” of the photodiode triggers negative feedback that causes the system to halt irradiation of the tissue along a path, until the next trial begins.

公开(公告)号：US10386650B2

公开(公告)日：2019-08-20

申请号：US15791025

申请日：2017-10-23

Applicant: Massachusetts Institute of Technology

Inventor： Barmak Heshmat Dehkordi ,  Albert Redo-Sanchez ,  Gordon Moseley Andrews ,  Ramesh Raskar

IPC: G01B9/02 ,  G01N21/47 ,  G02B27/10 ,  G02B27/58 ,  G01N21/3586

Abstract: A sample may be illuminated in such a way that light passes through the sample, reflects from a set of reflectors, passes through the sample again and travels to a light sensor. The reflectors may be staggered in depth beneath the sample, each reflector being at a different depth. Light reflecting from each reflector, respectively, may arrive at the light sensor during a different time interval than that in which light reflecting from other reflectors arrives—or may have a different phase than that of light reflecting from the other reflectors. The light sensor may separately measure light reflecting from each reflector, respectively. The reflectors may be extremely small, and the separate reflections from the different reflectors may be combined in a super-resolved image. The super-resolved image may have a spatial resolution that is better than that indicated by the diffraction limit.

公开(公告)号：US10260866B2

公开(公告)日：2019-04-16

申请号：US14979433

申请日：2015-12-27

Applicant: Massachusetts Institute of Technology

Inventor： Achuta Kadambi ,  Vage Taamazyan ,  Boxin Shi ,  Ramesh Raskar

IPC: H04N15/00 ,  G01B11/24 ,  G06T7/507 ,  G06T7/514

Abstract: A 3D imaging system uses a depth sensor to produce a coarse depth map, and then uses the coarse depth map as a constraint in order to correct ambiguous surface normals computed from polarization cues. The imaging system outputs an enhanced depth map that has a greater depth resolution than the coarse depth map. The enhanced depth map is also much more accurate than could be obtained from the depth sensor alone. In many cases, the imaging system extracts the polarization cues from three polarized images. Thus, in many implementations, the system takes only three extra images—in addition to data used to generate the coarse depth map—in order to dramatically enhance the coarse depth map.

公开(公告)号：US20190101631A1

公开(公告)日：2019-04-04

申请号：US16147870

申请日：2018-09-30

Applicant: Massachusetts Institute of Technology

Inventor： Achuta Kadambi ,  Tomohiro Maeda ,  Ayush Bhandari ,  Barmak Heshmat Dehkordi ,  Ramesh Raskar

IPC: G01S7/491 ,  G02F1/03 ,  G02F1/21 ,  G01S17/89 ,  G01S7/481

Abstract: A time-of-flight imaging system may output light with a modulation frequency in the gigahertz band, to illuminate a range target. This high-frequency illumination may enable extremely precise—e.g., micron-scale—depth measurements. The system may modulate reflected light from the range target, to create a beat tone that has a frequency in the hertz band. In some cases, the modulated light in the gigahertz band is created by a first modulator and the beat tone in the hertz band is created by a second modulator. In some cases, the modulated light in the gigahertz band is created by an upshift cascade of modulators and the beat tone in the hertz band is created by a downshift cascade of modulators. A photodetector may measure the low-frequency beat tone. From this beat tone, phase of the signal and depth of the range target may be extracted.

公开(公告)号：US10190983B2

公开(公告)日：2019-01-29

申请号：US15487438

申请日：2017-04-14

Applicant: Massachusetts Institute of Technology

Inventor： Ayush Bhandari ,  Christopher Barsi ,  Achuta Kadambi ,  Ramesh Raskar

IPC: G01N21/64

Abstract: A light source may illuminate a scene with pulsed light that is pulsed non-periodically. The scene may include fluorescent material that fluoresces in response to the pulsed light. The pulsed light signal may comprise a maximum length sequence or Gold sequence. A lock-in time-of-flight sensor may take measurements of light returning from the scene. A computer may, for each pixel in the sensor, perform a Discrete Fourier Transform on measurements taken by the pixel, in order to calculate a vector of complex numbers for the pixel. Each complex number in the vector may encode phase and amplitude of incident light at the pixel and may correspond to measurements taken at a given time interval during the pulsed light signal. A computer may, based on phase of the complex numbers for a pixel, calculate fluorescence lifetime and scene depth of a scene point that corresponds to the pixel.

公开(公告)号：US20180259455A1

公开(公告)日：2018-09-13

申请号：US15487438

申请日：2017-04-14

Applicant: Massachusetts Institute of Technology

Inventor： Ayush Bhandari ,  Christopher Barsi ,  Achuta Kadambi ,  Ramesh Raskar

IPC: G01N21/64

CPC classification number: G01N21/6408 ,  G01N21/6456 ,  G01N2201/0691 ,  G01N2201/126 ,  G01N2201/129 ,  G07D7/00

Abstract: A light source may illuminate a scene with pulsed light that is pulsed non-periodically. The scene may include fluorescent material that fluoresces in response to the pulsed light. The pulsed light signal may comprise a maximum length sequence or Gold sequence. A lock-in time-of-flight sensor may take measurements of light returning from the scene. A computer may, for each pixel in the sensor, perform a Discrete Fourier Transform on measurements taken by the pixel, in order to calculate a vector of complex numbers for the pixel. Each complex number in the vector may encode phase and amplitude of incident light at the pixel and may correspond to measurements taken at a given time interval during the pulsed light signal. A computer may, based on phase of the complex numbers for a pixel, calculate fluorescence lifetime and scene depth of a scene point that corresponds to the pixel.

公开(公告)号：US20180131851A1

公开(公告)日：2018-05-10

申请号：US15861645

申请日：2018-01-03

Applicant: Massachusetts Institute of Technology

Inventor： Barmak Heshmat Dehkordi ,  Ik Hyun Lee ,  Hisham Bedri ,  Ramesh Raskar

IPC: H04N5/225 ,  G02B6/06

CPC classification number: H04N5/2256 ,  G02B6/06 ,  H04N5/2257

Abstract: An open-ended, incoherent bundle of optical fibers transmits light from a nearby scene. A camera captures images of the back end of the fiber bundle. Because the fiber bundle is incoherent, the captured image is shuffled, in the sense that the relative position of pixels in the image differs from the relative position of the scene regions that correspond to the pixels. Calibration is performed in order to map from the front end positions to the back-end positions of the fibers. In the calibration, pulses of light are delivered, in such a way that the time at which light reflecting from a given pulse enters a given fiber directly correlates to the position of the front end of the given fiber. A time-of-flight sensor takes measurements indicative of these time signatures. Based on the map obtained from calibration, a computer de-shuffles the image.

公开(公告)号：US20180113321A1

公开(公告)日：2018-04-26

申请号：US15791025

申请日：2017-10-23

Applicant: Massachusetts Institute of Technology

Inventor： Barmak Heshmat Dehkordi ,  Albert Redo-Sanchez ,  Gordon Moseley Andrews ,  Ramesh Raskar

IPC: G02B27/58 ,  G02B27/10 ,  G01N21/3586

CPC classification number: G02B27/58 ,  G01B9/02018 ,  G01B9/02024 ,  G01B9/02025 ,  G01B9/02091 ,  G01N21/3586 ,  G01N21/4795 ,  G01N2021/4797 ,  G02B27/1066

Abstract: A sample may be illuminated in such a way that light passes through the sample, reflects from a set of reflectors, passes through the sample again and travels to a light sensor. The reflectors may be staggered in depth beneath the sample, each reflector being at a different depth. Light reflecting from each reflector, respectively, may arrive at the light sensor during a different time interval than that in which light reflecting from other reflectors arrives—or may have a different phase than that of light reflecting from the other reflectors. The light sensor may separately measure light reflecting from each reflector, respectively. The reflectors may be extremely small, and the separate reflections from the different reflectors may be combined in a super-resolved image. The super-resolved image may have a spatial resolution that is better than that indicated by the diffraction limit.

公开(公告)号：US20170212059A1

公开(公告)日：2017-07-27

申请号：US15266195

申请日：2016-09-15

Applicant: Massachusetts Institute of Technology ,  Board of Trustees of Michigan State University

Inventor： Gregory Charvat ,  Andrew Temme ,  Micha Feigin-Almon ,  Ramesh Raskar ,  Hisham Bedri

IPC: G01N22/00 ,  G01N21/35

CPC classification number: G01N22/00 ,  G01N21/3586 ,  G01S13/88 ,  G01S13/887

Abstract: An imaging system images near-field objects with focused microwave or terahertz radiation. Multiple antennas emit microwave or terahertz radiation, such that the radiation varies in frequency over time, illuminates a near-field object, reflects from the near-field object, and travels to a passive aperture. For example, the passive aperture may comprise a dielectric lens or a parabolic reflector. The passive aperture focuses, onto a spatial region, the microwave or terahertz radiation that reflected from the near-field object. One or more antennas take measurements, in the spatial region, of the microwave or terahertz radiation that reflected from the near-field object. A computer calculates, based on the measurements, an image of the near-field object and depth information regarding the near-field object.

公开(公告)号：US20160320837A1

公开(公告)日：2016-11-03

申请号：US15142165

申请日：2016-04-29

Applicant: Massachusetts Institute of Technology

Inventor： Tristan Swedish ,  Karin Roesch ,  Ramesh Raskar

IPC: G06F3/01 ,  G06K9/00 ,  G06F3/00

CPC classification number: G06F3/013 ,  G06F3/005 ,  G06K9/00604

Abstract: A video camera captures images of retroreflection from the retina of an eye. These images are captured while the eye rotates. Thus, different images are captured in different rotational positions of the eye. A computer calculates, for each image, the eye's direction of gaze. In turn, the direction of gaze is used to calculate the precise location of a small region of the retina at which the retroflection occurs. A computer calculates a digital image of a portion of the retina by summing data from multiple retroreflection images. The digital image of the retina may be used for many practical applications, including medical diagnosis and biometric identification. In some scenarios, the video camera captures detailed images of the retina of a subject, while the subject is so far away that the rest of the subject's face is below the diffraction limit of the camera.

Abstract translation: 视频摄像机从眼睛的视网膜拍摄回射的图像。 这些图像在眼睛旋转时被捕获。 因此，在眼睛的不同旋转位置捕获不同的图像。 计算机为每个图像计算眼睛的注视方向。 反过来，注视的方向用于计算出现逆行的视网膜的小区域的精确位置。 计算机通过对来自多个回射图像的数据求和来计算视网膜的一部分的数字图像。 视网膜的数字图像可用于许多实际应用，包括医学诊断和生物识别。 在某些情况下，摄像机会拍摄被摄物体的视网膜的详细图像，而拍摄对象距离较远，受试者脸部的其余部分低于摄像机的衍射极限。