Papers by Nicusor Iftimia
Investigative Ophthalmology & Visual Science, Jun 11, 2015
Optics Letters, Feb 10, 2020
In this Letter, we report a low-cost, portable, two-photon excitation fluorescence microscopy ima... more In this Letter, we report a low-cost, portable, two-photon excitation fluorescence microscopy imager that uses a fiber-based approach for both femtosecond supercontinuum (SC) generation and light delivery to the optical head. The SC generation is based on a tapered polarization-maintaining photonic crystal fiber that uses pre-chirped femtosecond narrowband pulses to generate a coherent SC spectrum with a bandwidth of approximately 300 nm. Using this approach, high-power, near-transform-limited, wavelength-selectable SC pulses are generated and directly delivered to the imaging optical head. Preliminary testing of this imager on brain slices is presented, demonstrating a high signal-to-noise ratio and sub-cellular imaging capabilities to a depth of approximately 200 µm. These results demonstrate the suitability of the technology for ex vivo and potentially in vivo cellular-level biomedical imaging applications.
Optics Express, Jun 4, 2009
We have developed a compact retinal imager that integrates adaptive optics (AO) into a line scann... more We have developed a compact retinal imager that integrates adaptive optics (AO) into a line scanning ophthalmoscope (LSO). The bench-top AO-LSO instrument significantly reduces the size, complexity, and cost of research AO scanning laser ophthalmoscopes (AOSLOs), for the purpose of moving adaptive optics imaging more rapidly into routine clinical use. The AO-LSO produces high resolution retinal images with only one moving part and a significantly reduced instrument footprint and number of optical components. The AO-LSO has a moderate field of view (5.5 deg), which allows montages of the macula or other targets to be obtained more quickly and efficiently. In a preliminary human subjects investigation, photoreceptors could be resolved and counted within ~0.5 mm of the fovea. Photoreceptor counts matched closely to previously reported histology. The capillaries surrounding the foveal avascular zone could be resolved, as well as cells flowing within them. Individual nerve fiber bundles could be resolved, especially near the optic nerve head, as well as other structures such as the lamina cribrosa. In addition to instrument design, fabrication, and testing, software algorithms were developed for automated image registration and cone counting.
Optics Express, Aug 20, 2008
We have developed a dual-beam Fourier domain optical Doppler tomography (FD-ODT) system to image ... more We have developed a dual-beam Fourier domain optical Doppler tomography (FD-ODT) system to image zebrafish (Danio rerio) larvae. Two beams incident on the zebrafish with a fixed angular separation allow absolute blood flow velocity measurement to be made regardless of vessel orientation in a sagittal plane along which the heart and most of the major vasculature lie. Two spectrometers simultaneously acquire spectra from two interferometers with a typical (maximum) line rate of 18 (28) kHz. The system was calibrated using diluted milk and microspheres and a 0.5-mm thick flow cell. The average deviation from the set velocity from 1.4 to 34.6 mm/s was 4.1%. Three-dimensional structural raster videos were acquired of an entire fish, and through the head, heart, and upper tail of the fish. Coarse features that were resolved include the telencephalon, retina, both heart chambers (atrium and ventricle), branchial arches, and notochord. Other fine structures within these organs were also resolved. Zebrafish are an important tool for high-throughput screening of new pharmacological agents. The ability to generate high-resolution three-dimensional structural videos and accurately measure absolute flow rates in major vessels with FD-ODT provides researchers with additional metrics by which the efficacy of new drugs can be assessed.
Simultaneous multi-channels offset imaging provides isotropic images of retinal microstructures f... more Simultaneous multi-channels offset imaging provides isotropic images of retinal microstructures free of directionality artifacts and enables phase imaging in the living eye with enhanced visualization contrast.
Advanced Biomedical and Clinical Diagnostic and Surgical Guidance Systems XXI
Biophotonics Congress: Biomedical Optics 2022 (Translational, Microscopy, OCT, OTS, BRAIN)
Optical Biopsy XVII: Toward Real-Time Spectroscopic Imaging and Diagnosis, 2019
Biomedical Optics Express, 2018
The platform described here combines the non-invasive measurement of the retina/choroid structure... more The platform described here combines the non-invasive measurement of the retina/choroid structure and ocular blood flow based on optical coherence tomography (OCT) and wide-field semi-quantitative global flow visualization using line-scanning Doppler flowmetry (LSDF). The combination of these two imaging modalities within the same platform enables comprehensive assessment of blood flow in the retina and choroid in animals and human subjects for diagnostic purposes. Ultra-widefield vasculature visualization is demonstrated here for the first time without injecting additional contrast agents and based only on the motion of particles within the vasculature.
Conference on Lasers and Electro-Optics, 2016
We report on two-photon microscopy (TPM) imaging based on a coherent fiber-based supercontinuum s... more We report on two-photon microscopy (TPM) imaging based on a coherent fiber-based supercontinuum source. The supercontinuum generation in a photonic crystal fiber induced by fiber-delivered ultrashort (∼ 100 fs) laser pulses, enables high-resolution TPM fluorescence imaging in multiple spectral bands.
IEEE Transactions on Medical Imaging, 2001
We present for the first time a full three-dimensional (3-D) reconstruction of absorption images ... more We present for the first time a full three-dimensional (3-D) reconstruction of absorption images of breast from continuous-wave (cw) measurements performed on a premenopausal woman. Our 3-D optical images clearly reveal a large primary tumor as well as a small secondary tumor in a separate location of the breast. The multiple tumors identified by our 3-D optical imaging have been confirmed by the subsequent biopsy examination of the breast. Quantitative information of the optical images obtained is provided in terms of the location, size, and absorption coefficient of the tumors.
Diagnostics, Jul 6, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
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Papers by Nicusor Iftimia