Pavan Chandra Konda

Pavan Chandra Konda
Duke University | DU · Department of Biomedical Engineering (BME)

Doctor of Philosophy

About

51
Publications
12,054
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323
Citations
Introduction
I am currently a postdoctoral researcher in the computational optics lab at the Duke university led by Dr. Roarke Horstmeyer. My current research interests are in the areas of computational imaging, novel microscopy methods, low-cost microscopy, high-speed gigapixel imaging, micro-endoscopy and in vivo imaging. Other areas of expertise include multi-spectral imaging, extended depth-of-field imaging, compressive sensing and speckle imaging. My current research focuses on developing gigapixel imaging systems, Fourier ptychographic microscopy and miniaturised microscopes for imaging rodent brain activity. In the past I have developed imaging systems using GRIN lenses for minimally invasive microscopy in rodents to enable longitudinal studies in the spinal cord of a rodent.

Publications

Publications (51)
Conference Paper
Full-text available
Obtaining gigapixel images is a challenging task because of the aberrations present in a conventional optical system, small sensor sizes and limited data-capture rates of cameras. Multi-aperture Fourier ptychography (MAFP) was proposed recently by us to solve the issue of increasing the data acquisition bandwidth by parallelizing data capture using...
Preprint
We report a novel microscopy platform, termed Multi-Aperture Fourier ptychographic microscopy (MA-FPM), capable of realizing gigapixel complex field images with large data acquisition bandwidths - in gigapixels per second. MA-FPM is a synthetic aperture technique- an array of objectives together with tilt-shift illumination are used to synthesize h...
Article
Full-text available
The revolution in low-cost consumer photography and computation provides fertile opportunity for a disruptive reduction in the cost of biomedical imaging. Conventional approaches to low-cost microscopy are fundamentally restricted, however, to modest field of view (FOV) and/or resolution. We report a low-cost microscopy technique, implemented with...
Article
The ability of a microscope to rapidly acquire wide-field, high-resolution images is limited by both the optical performance of the microscope objective and the bandwidth of the detector. The use of multiple detectors can increase electronic-acquisition bandwidth, but the use of multiple parallel objectives is problematic since phase coherence is r...
Article
Full-text available
Fast noninvasive probing of spatially varying decorrelating events, such as cerebral blood flow beneath the human skull, is an essential task in various scientific and clinical settings. One of the primary optical techniques used is diffuse correlation spectroscopy (DCS), whose classical implementation uses a single or few single-photon detectors,...
Article
Full-text available
Noninvasive optical imaging through dynamic scattering media has numerous important biomedical applications but still remains a challenging task. While standard diffuse imaging methods measure optical absorption or fluorescent emission, it is also well‐established that the temporal correlation of scattered coherent light diffuses through tissue muc...
Preprint
Full-text available
Fast noninvasive probing of spatially varying decorrelating events, such as cerebral blood flow beneath the human skull, is an essential task in various scientific and clinical settings. One of the primary optical techniques used is diffuse correlation spectroscopy (DCS), whose classical implementation uses a single or few single-photon detectors,...
Article
This paper presents a microscopic imaging technique that uses variable-angle illumination to recover the complex polarimetric properties of a specimen at high resolution and over a large field-of-view. The approach extends Fourier ptychography, which is a synthetic aperture-based imaging approach to improve resolution with phaseless measurements, t...
Conference Paper
We present a new interleaved multi-camera microscope architecture and a physics-supervised multi-ocular stereo neural network that enable simultaneous photometric and 3D topographic imaging of freely-moving organisms over 135 cm ² at throughputs exceeding 5 gigapixels per second.
Article
This work demonstrates a multi-lens microscopic imaging system that overlaps multiple independent fields of view on a single sensor for high-efficiency automated specimen analysis. Automatic detection, classification and counting of various morphological features of interest is now a crucial component of both biomedical research and disease diagnos...
Preprint
Full-text available
This work demonstrates a multi-lens microscopic imaging system that overlaps multiple independent fields of view on a single sensor for high-efficiency automated specimen analysis. Automatic detection, classification and counting of various morphological features of interest is now a crucial component of both biomedical research and disease diagnos...
Preprint
Full-text available
The dynamics of living organisms are organized across many spatial scales, yet existing, cost-effective imaging systems can measure only a subset of these scales at once. Here, we have created a scalable multi-camera array microscope (MCAM) that enables comprehensive high-resolution recording from multiple spatial scales simultaneously, ranging fro...
Article
Recently developed single-photon avalanche diode (SPAD) array cameras provide single-photon sensitivity and picosecond-scale time gating for time-of-flight measurements, with applications in LIDAR and fluorescence lifetime imaging. As compared to standard image sensors, SPAD arrays typically return binary intensity measurements with photon time-of-...
Preprint
Full-text available
Noninvasive optical imaging through dynamic scattering media has numerous important biomedical applications but still remains a challenging task. While standard methods aim to form images based upon optical absorption or fluorescent emission, it is also well-established that the temporal correlation of scattered coherent light diffuses through tiss...
Article
We present a novel microscopy concept, termed Multi-Aperture Fourier ptychographic microscopy (MA-FPM), to enable implementation of parallel detectors in microscopy to increase the space-bandwidth-time product. MA-FPM is a synthetic aperture technique: an array of objectives together with tilt-shift illumination are used to synthesize high-resoluti...
Article
Full-text available
Diffuse correlation spectroscopy (DCS) is a well-established method that measures rapid changes in scattered coherent light to identify blood flow and functional dynamics within a tissue. While its sensitivity to minute scatterer displacements leads to a number of unique advantages, conventional DCS systems become photon-limited when attempting to...
Conference Paper
We demonstrate a multi-lenses microscopic imaging system that records over- lapping fields-of-view for high-efficiency automated specimen analysis. We show both in simulation and experiment how our system can achieve accurate target object detection on overlapped images.
Conference Paper
We present a new high-speed Fourier ptychographic imaging technique using multiple-cameras and LED multiplexing. With our technique even the fastest LED multiplexed implementations can be further sped-up by at-least one order of magnitude.
Article
Standard microscopes offer a variety of settings to help improve the visibility of different specimens to the end microscope user. Increasingly, however, digital microscopes are used to capture images for automated interpretation by computer algorithms (e.g., for feature classification, detection, or segmentation), often without any human involveme...
Preprint
Full-text available
Diffuse correlation spectroscopy (DCS) is a well-established method that measures rapid changes in scattered coherent light to identify blood flow and functional dynamics within tissue. While its sensitivity to minute scatterer displacements leads to a number of unique advantages, conventional DCS systems become photon-limited when attempting to pr...
Preprint
Full-text available
Standard microscopes offer a variety of settings to help improve the visibility of different specimens to the end microscope user. Increasingly, however, digital microscopes are used to capture images for automated interpretation by computer algorithms (e.g., for feature classification, detection or segmentation), often without any human involvemen...
Preprint
Full-text available
This paper introduces a supervised deep-learning network that jointly optimizes the physical setup of an optical microscope to infer fluorescence image information. Specifically, we design a bright-field microscope's illumination module to maximize the performance for inference of fluorescent cellular features from bright-field imagery. We take adv...
Conference Paper
Full-text available
We describe a visible-light multi-spectral system for vascular oximetry studies that can be implemented in lowand middle-income countries, using a low-cost electronics and optical elements, for instance a Raspberry Pi, a Pi camera under a resolution of 5-megapixel, 2592x1944-pixel resolution, and four different light sources at 480nm, 532nm, 593nm...
Article
Full-text available
Traditional imaging systems exhibit a well-known trade-off between the resolution and the field of view of their captured images. Typical cameras and microscopes can either "zoom in" and image at high-resolution, or they can "zoom out" to see a larger area at lower resolution, but can rarely achieve both effects simultaneously. In this review, we p...
Conference Paper
We develop a highly parallelized DCS system using a 32 × 32 single-photon avalanche diode array, and demonstrate its sensitivity improvement in a DMD-based phantom study and an in vivo forehead blood flow experiment.
Article
Full-text available
Since its invention, the microscope has been optimized for interpretation by a human observer. With the recent development of deep learning algorithms for automated image analysis, there is now a clear need to re-design the microscope’s hardware for specific interpretation tasks. To increase the speed and accuracy of automated image classification,...
Article
Full-text available
Extracting as much information as possible about an object when probing with a limited number of photons is an important goal with applications from biology and security to metrology. Imaging with a few photons is a challenging task as the detector noise and stray light are then predominant, which precludes the use of conventional imaging methods....
Preprint
Full-text available
Extracting as much information as possible about an object when probing with a limited number of photons is an important goal with applications from biology and security to metrology. Imaging with a few photons is a challenging task as the detector noise and stray light are then predominant, which precludes the use of conventional imaging methods....
Conference Paper
Full-text available
We demonstrate aperture-synthetic diffracted field measurement using multiple mutually incoherent cameras in Fourier ptychography to provide a scaleable increase in data acquisition bandwidth. Our nine-camera system enables an order of magnitude improvement in image acquisition speed.
Conference Paper
We present a multi-aperture gigapixel microscope that is capable of imaging a 600cm2 area at 10 micrometer resolution and can simultaneously track the depth of objects within the scene. We demonstrate this capability by tracking freely swimming zebrafish larvae in a large petri dish.
Conference Paper
We present a multispectral imaging mini-microscope for longitudinal oximetry in small animals. By replacing expensive and complex imaging systems using a low-cost imaging system.
Article
We present a multispectral imaging mini-microscope for longitudinal oximetry in small animals. By replacing expensive and complex imaging systems using a low-cost imaging system.
Preprint
Full-text available
Full text at: https://www.biorxiv.org/content/early/2018/11/02/460055 . Abstract: The revolution in low-cost consumer photography and computation provides fertile opportunity for a disruptive reduction in the cost of biomedical imaging. Conventional approaches to low-cost microscopy are fundamentally restricted, however, to modest field of view (F...
Conference Paper
Full-text available
We report a custom epi-fluorescent microscope setup using GRIN lens microendoscopes for minimally invasive microscopic imaging in rodents. A simple scanning system and deconvolution provides high quality wide field-of-view images through these highly aberrated endoscopes.
Conference Paper
Full-text available
We report a Fourier ptychographic setup with sub-micron resolution costing around £100 using mobile phone camera sensors. Reconstruction algorithms were developed to overcome the Bayer pattern on these sensors and robust calibration methods have been developed to tackle alignment errors.
Conference Paper
Full-text available
We report a Fourier ptychography reconstruction that enabled the use of low-cost Bayer-filtered color cameras. Using 3D-printing, consumer electronics and robust calibration we demonstrated a microscope capable of capturing sub-micron resolution 25-megapixel images under $150.
Conference Paper
Full-text available
We present a new optical configuration using the Scheimpflug principle for Fourier ptychography microscopy. This configuration minimizes the aberrations present in the off-axis lenses of a multi-aperture Fourier ptychography setup. A 3D printed setup was used to demonstrate the experimental implementation.
Conference Paper
Full-text available
We report a Fourier ptychography setup using a raspberry pi camera sensor and its lens in reversed configuration. In this work data acquisition was performed by means of a raspberry pi board which eliminates the requirement of a computer for data acquisition thus allowing a miniaturized system for remote data acquisition costing around £100.
Conference Paper
We report new calibration and aberration correction procedures in Multi-Aperture Fourier Ptychography which can register images from different cameras with subpixel accuracy and corrects for unknown aberrations more effectively removing artefacts and drastically improving the image reconstruction quality.
Conference Paper
Full-text available
The spatial resolution of a microscope is inversely proportionate to the sum of the objective numerical aperture (NA) and the illumination NA. Fourier Ptychography (FP) microscopy achieves high-resolution, wide-field imaging by the use of a low-NA, wide-field objective combined with time-sequential synthesis of high NA illumination using an array o...
Conference Paper
Full-text available
We report a novel multi-aperture Fourier Ptychography combined with new algorithms for near-field reconstruction that promises an order of magnitude reduction in acquisition time and the possibility of acquiring Fourier Ptychography datasets at 1Hz.

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Projects (2)
Project
Multi-aperture Fourier ptychography aims to use parallel objectives to improve the data acquisition speed in Fourier ptychography Raspberry Pi Fourier ptychography is an open-source project which uses Raspberry Pi hardware to build a portable, robust, miniaturized Fourier ptychographic microscope costing around $150