Vivek K Goyal
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View article: Free-running vs. Synchronous: Single-Photon Lidar for High-flux 3D Imaging
Free-running vs. Synchronous: Single-Photon Lidar for High-flux 3D Imaging Open
Conventional wisdom suggests that single-photon lidar (SPL) should operate in low-light conditions to minimize dead-time effects. Many methods have been developed to mitigate these effects in synchronous SPL systems. However, solutions for…
View article: Turning rough surfaces into non-line-of-sight cameras
Turning rough surfaces into non-line-of-sight cameras Open
Overcoming the spatial mixing of reflection and scattering from rough surfaces to see a hidden scene is a difficult challenge with a wide range of applications. Existing methods counter the mixing effect using active time-of-flight or cohe…
View article: Shot noise-mitigated secondary electron imaging with ion count-aided microscopy
Shot noise-mitigated secondary electron imaging with ion count-aided microscopy Open
Modern science is dependent on imaging on the nanoscale, often achieved through processes that detect secondary electrons created by a highly focused incident charged particle beam. Multiple types of measurement noise limit the ultimate tr…
View article: Contralateral anaesthesia following peribulbar block- Unveiling a rare ocular complication
Contralateral anaesthesia following peribulbar block- Unveiling a rare ocular complication Open
Peribulbar anesthesia is a common regional block in intraocular surgeries with an excellent safety profile. We report a rare case of contralateral loss of accommodation and extraocular muscle palsy following peribulbar block (PBB). A patie…
View article: Image Reconstruction from Readout-Multiplexed Single-Photon Detector Arrays
Image Reconstruction from Readout-Multiplexed Single-Photon Detector Arrays Open
Readout multiplexing is a promising solution to overcome hardware limitations and data bottlenecks in imaging with single-photon detectors. Conventional multiplexed readout processing creates an upper bound on photon counts at a very fine …
View article: Absorption-based hyperspectral thermal ranging: performance analyses, optimization, and simulations
Absorption-based hyperspectral thermal ranging: performance analyses, optimization, and simulations Open
The wavelength dependence of atmospheric absorption creates range cues in hyperspectral measurements that can be exploited for passive ranging using only thermal emissions. In this work, we present fundamental limits on absorption-based ra…
View article: Shot noise-mitigated secondary electron imaging with ion count-aided microscopy
Shot noise-mitigated secondary electron imaging with ion count-aided microscopy Open
Modern science is dependent on imaging on the nanoscale, often achieved through processes that detect secondary electrons created by a highly focused incident charged particle beam. Multiple types of measurement noise limit the ultimate tr…
View article: Absorption-Based, Passive Range Imaging from Hyperspectral Thermal Measurements
Absorption-Based, Passive Range Imaging from Hyperspectral Thermal Measurements Open
Passive hyperspectral longwave infrared measurements are remarkably informative about the surroundings. Remote object material and temperature determine the spectrum of thermal radiance, and range, air temperature, and gas concentrations d…
View article: Fourier-ring Correlation Resolution for Time-resolved Measurement in Charged Particle Microscopy
Fourier-ring Correlation Resolution for Time-resolved Measurement in Charged Particle Microscopy Open
Time-Resolved Measurement (TRM) has been proposed as a method to improve charged particle microscopy.Under the assumption of direct secondary electron (SE) detection, TRM has been shown to reduce the mean-squared error (MSE) of estimation …
View article: Progress in Secondary Electron Yield Mapping in Charged Particle Microscopy
Progress in Secondary Electron Yield Mapping in Charged Particle Microscopy Open
Journal Article Progress in Secondary Electron Yield Mapping in Charged Particle Microscopy Get access Akshay Agarwal, Akshay Agarwal Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA Corresponding autho…
View article: Non-line-of-sight snapshots and background mapping with an active corner camera
Non-line-of-sight snapshots and background mapping with an active corner camera Open
The ability to form reconstructions beyond line-of-sight view could be transformative in a variety of fields, including search and rescue, autonomous vehicle navigation, and reconnaissance. Most existing active non-line-of-sight (NLOS) ima…
View article: Continuous-Time Modeling and Analysis of Particle Beam Metrology
Continuous-Time Modeling and Analysis of Particle Beam Metrology Open
Particle beam microscopy (PBM) performs nanoscale imaging by pixelwise capture of scalar values representing noisy measurements of the response from secondary electrons (SEs) integrated over a dwell time. Extended to metrology, goals inclu…
View article: MEGS: A Penalty for Mutually Exclusive Group Sparsity
MEGS: A Penalty for Mutually Exclusive Group Sparsity Open
Penalty functions or regularization terms that promote structured solutions to optimization problems are of great interest in many fields. We introduce MEGS, a nonconvex structured sparsity penalty that promotes mutual exclusivity between …
View article: Denoising Particle Beam Micrographs with Plug-and-Play Methods
Denoising Particle Beam Micrographs with Plug-and-Play Methods Open
In a particle beam microscope, a raster-scanned focused beam of particles interacts with a sample to generate a secondary electron (SE) signal pixel by pixel. Conventionally formed micrographs are noisy because of limitations on acquisitio…
View article: Non-Line-of-Sight Tracking and Mapping with an Active Corner Camera
Non-Line-of-Sight Tracking and Mapping with an Active Corner Camera Open
The ability to form non-line-of-sight (NLOS) images of changing scenes could be transformative in a variety of fields, including search and rescue, autonomous vehicle navigation, and reconnaissance. Most existing active NLOS methods illumi…
View article: Online Beam Current Estimation in Particle Beam Microscopy
Online Beam Current Estimation in Particle Beam Microscopy Open
In conventional particle beam microscopy, knowledge of the beam current is essential for accurate micrograph formation and sample milling. This generally necessitates offline calibration of the instrument. In this work, we establish that b…
View article: Secondary Electron Count Imaging in SEM
Secondary Electron Count Imaging in SEM Open
Scanning electron microscopy (SEM) is a versatile technique used to image samples at the nanoscale. Conventional imaging by this technique relies on finding the average intensity of the signal generated on a detector by secondary electrons…
View article: Prevention Beats Removal: Avoiding Stripe Artifacts from Current Variation in Particle Beam Microscopy Through Time-Resolved Sensing
Prevention Beats Removal: Avoiding Stripe Artifacts from Current Variation in Particle Beam Microscopy Through Time-Resolved Sensing Open
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View article: Non–line-of-sight imaging over 1.43 km
Non–line-of-sight imaging over 1.43 km Open
Significance Non–line-of-sight (NLOS) imaging can recover details of a hidden scene from the indirect light that has scattered multiple times. Despite recent advances, NLOS imaging has remained at short-range verifications. Here, both expe…
View article: Supplementary document for High-Flux Single-Photon Lidar - 4880061.pdf
Supplementary document for High-Flux Single-Photon Lidar - 4880061.pdf Open
Supplemental document
View article: Time-Resolved Focused Ion Beam Microscopy: Modeling, Estimation Methods, and Analyses
Time-Resolved Focused Ion Beam Microscopy: Modeling, Estimation Methods, and Analyses Open
In a focused ion beam (FIB) microscope, source particles interact with a small volume of a sample to generate secondary electrons that are detected, pixel by pixel, to produce a micrograph. Randomness of the number of incident particles ca…
View article: High-flux single-photon lidar
High-flux single-photon lidar Open
In time-correlated single-photon counting (TCSPC), photons that arrive during the detector and timing electronics dead times are missed, causing distortion of the detection time distribution. Conventional wisdom holds that TCSPC should be …
View article: Two-Dimensional Non-Line-of-Sight Scene Estimation From a Single Edge Occluder
Two-Dimensional Non-Line-of-Sight Scene Estimation From a Single Edge Occluder Open
Passive non-line-of-sight imaging methods are often faster and stealthier than their active counterparts, requiring less complex and costly equipment. However, many of these methods exploit motion of an occluder or the hidden scene, or req…
View article: Dithered depth imaging
Dithered depth imaging Open
Single-photon lidar (SPL) is a promising technology for depth measurement at long range or from weak reflectors because of the sensitivity to extremely low light levels. However, constraints on the timing resolution of existing arrays of s…
View article: Compressively sampling the optical transmission matrix of a multimode fibre
Compressively sampling the optical transmission matrix of a multimode fibre Open
Measurement of the optical transmission matrix (TM) of an opaque material is an advanced form of space-variant aberration correction. Beyond imaging, TM-based methods are emerging in a range of fields including optical communications, opti…