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Lee S, Choi SS, Meleppat RK, Zawadzki RJ, Doble N. High-speed, phase contrast retinal and blood flow imaging using an adaptive optics partially confocal multi-line ophthalmoscope. BIOMEDICAL OPTICS EXPRESS 2024; 15:1815-1830. [PMID: 38495707 PMCID: PMC10942708 DOI: 10.1364/boe.507449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/18/2023] [Accepted: 01/14/2024] [Indexed: 03/19/2024]
Abstract
High-speed, phase contrast retinal and blood flow imaging using an adaptive optics partially confocal multi-line ophthalmosocope (AO-pcMLO) is described. It allows for simultaneous confocal and phase contrast imaging with various directional multi-line illumination by using a single 2D camera and a digital micromirror device (DMD). Both vertical and horizontal line illumination directions were tested, for photoreceptor and vascular imaging. The phase contrast imaging provided improved visualization of retinal structures such as cone inner segments, vessel walls and red blood cells with images being acquired at frame rates up to 500 Hz. Blood flow velocities of small vessels (<40 µm in diameter) were measured using kymographs for capillaries and cross-correlation between subsequent images for arterioles or venules. Cardiac-related pulsatile patterns were observed with normal resting heart-beat rate, and instantaneous blood flow velocities from 0.7 to 20 mm/s were measured.
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Affiliation(s)
- Soohyun Lee
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, Ohio 43210, USA
| | - Stacey S. Choi
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, Ohio 43210, USA
- Department of Ophthalmology and Visual Sciences, Havener Eye Institute, The Ohio State University, 915 Olentangy River Road, Suite 5000, Ohio 43212, USA
| | - Ratheesh K. Meleppat
- UC Davis Eye Center, Department of Ophthalmology and Vision Science, University of California, Davis, 4860 Y Street, Suite 2400, Sacramento, California 95817, USA
- UC Davis EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California, Davis, 4320 Tupper Hall, Davis, California 95616, USA
| | - Robert J. Zawadzki
- UC Davis Eye Center, Department of Ophthalmology and Vision Science, University of California, Davis, 4860 Y Street, Suite 2400, Sacramento, California 95817, USA
- UC Davis EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California, Davis, 4320 Tupper Hall, Davis, California 95616, USA
| | - Nathan Doble
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, Ohio 43210, USA
- Department of Ophthalmology and Visual Sciences, Havener Eye Institute, The Ohio State University, 915 Olentangy River Road, Suite 5000, Ohio 43212, USA
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Rutkauskas D, Auksorius E. Programmable high-speed confocal reflectance microscopy enabled by a digital micromirror device. OPTICS LETTERS 2024; 49:686-689. [PMID: 38300090 DOI: 10.1364/ol.511601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 01/03/2024] [Indexed: 02/02/2024]
Abstract
The digital micromirror device (DMD) has been used to achieve parallel scanning in confocal microscopy significantly increasing acquisition speed. However, for confocal reflectance imaging, such an approach is limited to mostly surface imaging due to strong backreflections coming from the DMD that can dominate the signal recorded on a camera. Here, we report on an optical configuration that uses separate areas of DMD to generate multiple spots and pinholes and thereby prevents backreflections from the DMD from reaching the camera. We thus demonstrate confocal imaging of weakly reflecting objects, such as a pollen grain sample.
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Samanta R, Mujumdar S. Controlling the transmission of broadband light through scattering media using a digital micromirror device. OPTICS LETTERS 2023; 48:4241-4244. [PMID: 37582002 DOI: 10.1364/ol.495297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/11/2023] [Indexed: 08/17/2023]
Abstract
Wavefront shaping has emerged as a valuable technique in complex photonics, wherein the various eigenmodes of the disordered medium are selectively excited to control the overall transmission through the medium. The process utilizes active optical devices such as liquid crystal-based spatial light modulators (LC-SLM), deformable mirrors (DM), and digital micromirror devices (DMD). Among these, the latter is preferred for imaging through dynamic scattering media such as living biological tissues due to their high-speed refresh rate and increased resolution. This study employs a genetic algorithm along with binary amplitude modulation generated by a digital micromirror device to spatially and spectrally control the large spectral bandwidth through a scattering medium. We illustrate spatial single-point focusing of broadband light, multipoint focusing of broadband light, and programmable spectral filtering of the same through disordered samples.
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Lee S, Choi SS, Meleppat RK, Zawadzki RJ, Doble N. Programmable, high-speed, adaptive optics partially confocal multi-spot ophthalmoscope using a digital micromirror device. OPTICS LETTERS 2023; 48:791-794. [PMID: 36723590 PMCID: PMC10422682 DOI: 10.1364/ol.480688] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 01/01/2023] [Indexed: 06/18/2023]
Abstract
A high-speed, adaptive optics partially confocal multi-spot ophthalmoscope (AO-pcMSO) using a digital micromirror device (DMD) in the illumination channel and a fast 2D CMOS camera is described. The camera is synchronized with the DMD allowing projection of multiple, simultaneous AO-corrected spots onto the human retina. Spatial filtering on each raw retinal image before reconstruction works as an array virtual pinholes. A frame acquisition rate of 250 fps is achieved by applying this parallel projection scheme. The contrast improves by 2-3 fold when compared to a standard flood illumination architecture. Partially confocal images of the human retina show cone and rod photoreceptors over a range of retinal eccentricities.
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Affiliation(s)
- Soohyun Lee
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, OH 43221
| | - Stacey S. Choi
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, OH 43221
- Department of Ophthalmology and Visual Science, Havener Eye Institute, The Ohio State University, 915 Olentangy River Road Suite 5000, OH 43212
| | - Ratheesh K. Meleppat
- UC Davis Eye Center, Department of Ophthalmology and Vision Science, University of California Davis, 4860 Y Street, Suite 2400, Sacramento, CA 95817
- UC Davis EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616
| | - Robert J. Zawadzki
- UC Davis Eye Center, Department of Ophthalmology and Vision Science, University of California Davis, 4860 Y Street, Suite 2400, Sacramento, CA 95817
- UC Davis EyePod Small Animal Ocular Imaging Laboratory, Department of Cell Biology and Human Anatomy, University of California Davis, 4320 Tupper Hall, Davis, CA 95616
| | - Nathan Doble
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, OH 43221
- Department of Ophthalmology and Visual Science, Havener Eye Institute, The Ohio State University, 915 Olentangy River Road Suite 5000, OH 43212
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Kumar P, Nishchal NK. Phase response optimization of a liquid crystal spatial light modulator with partially coherent light. APPLIED OPTICS 2021; 60:10795-10801. [PMID: 35200838 DOI: 10.1364/ao.439654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/04/2021] [Indexed: 06/14/2023]
Abstract
This paper demonstrates a method to determine and calibrate the modulation characteristics of a liquid crystal spatial light modulator (SLM) for on-axis phase response with partially coherent light. A polarimetric approach has been implemented to obtain the phase characterization curve of the SLM. The corrections for phase response errors exhibited by SLM have been incorporated through encoded grayscale patterns to ensure a spatially uniform phase response and a linear relationship between addressed phase and phase delay by SLM. In this approach, corrections can be applied at selective pixels of the SLM's display without altering its gamma curve. Experimental results are presented that verify the feasibility of the proposed approach.
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Bartuzel MM, Wróbel K, Tamborski S, Meina M, Nowakowski M, Dalasiński K, Szkulmowska A, Szkulmowski M. High-resolution, ultrafast, wide-field retinal eye-tracking for enhanced quantification of fixational and saccadic motion. BIOMEDICAL OPTICS EXPRESS 2020; 11:3164-3180. [PMID: 32637248 PMCID: PMC7316009 DOI: 10.1364/boe.392849] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/30/2020] [Accepted: 05/07/2020] [Indexed: 05/23/2023]
Abstract
We introduce a novel, noninvasive retinal eye-tracking system capable of detecting eye displacements with an angular resolution of 0.039 arcmin and a maximum velocity of 300°/s across an 8° span. Our system is designed based on a confocal retinal imaging module similar to a scanning laser ophthalmoscope. It utilizes a 2D MEMS scanner ensuring high image frame acquisition frequencies up to 1.24 kHz. In contrast with leading eye-tracking technology, we measure the eye displacements via the collection of the observed spatial excursions for all the times corresponding a full acquisition cycle, thus obviating the need for both a baseline reference frame and absolute spatial calibration. Using this approach, we demonstrate the precise measurement of eye movements with magnitudes exceeding the spatial extent of a single frame, which is not possible using existing image-based retinal trackers. We describe our retinal tracker, tracking algorithms and assess the performance of our system by using programmed artificial eye movements. We also demonstrate the clinical capabilities of our system with in vivo subjects by detecting microsaccades with angular extents as small as 0.028°. The rich kinematic ocular data provided by our system with its exquisite degree of accuracy and extended dynamic range opens new and exciting avenues in retinal imaging and clinical neuroscience. Several subtle features of ocular motion such as saccadic dysfunction, fixation instability and abnormal smooth pursuit can be readily extracted and inferred from the measured retinal trajectories thus offering a promising tool for identifying biomarkers of neurodegenerative diseases associated with these ocular symptoms.
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Affiliation(s)
- Maciej M. Bartuzel
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, Toruń 87-100, Poland
- Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wyb. Wyspiańskiego 27, Wrocław 50-370, Poland
| | - Krystian Wróbel
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, Toruń 87-100, Poland
| | - Szymon Tamborski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, Toruń 87-100, Poland
| | - Michał Meina
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, Toruń 87-100, Poland
- AM2M Ltd. L.P., Mickiewicza 7/17, Toruń 87-100, Poland
| | | | | | | | - Maciej Szkulmowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Grudziądzka 5, Toruń 87-100, Poland
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Damodaran M, Amelink A, de Boer JF. Optimal wavelengths for subdiffuse scanning laser oximetry of the human retina. JOURNAL OF BIOMEDICAL OPTICS 2018; 23:1-15. [PMID: 30152203 DOI: 10.1117/1.jbo.23.8.086003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 08/02/2018] [Indexed: 06/08/2023]
Abstract
Retinal blood vessel oxygenation is considered to be an important marker for numerous eye diseases. Oxygenation is typically assessed by imaging the retinal vessels at different wavelengths using multispectral imaging techniques, where the choice of wavelengths will affect the achievable measurement accuracy. Here, we present a detailed analysis of the error propagation of measurement noise in retinal oximetry, to identify optimal wavelengths that will yield the lowest uncertainty in saturation estimation for a given measurement noise level. In our analysis, we also investigate the effect of hemoglobin packing in discrete blood vessels (pigment packaging), which may result in a nonnegligible bias in saturation estimation if unaccounted for under specific geometrical conditions, such as subdiffuse sampling of smaller blood vessels located deeper within the retina. Our analyses show that using 470, 506, and 592 nm, a fairly accurate estimation of the whole oxygen saturation regime [0 1] can be realized, even in the presence of the pigment packing effect. To validate the analysis, we developed a scanning laser ophthalmoscope to produce high contrast images with a maximum pixel rate of 60 kHz and a maximum 30-deg imaging field of view. Confocal reflectance measurements were then conducted on a tissue-mimicking scattering phantom with optical properties similar to retinal tissue including narrow channels filled with absorbing dyes to mimic blood vessels. By imaging at three optimal wavelengths, the saturation of the dye combination was calculated. The experimental values show good agreement with our theoretical derivations.
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Affiliation(s)
- Mathi Damodaran
- Vrije Universiteit Amsterdam, LaserLaB, Department of Physics and Astronomy, Amsterdam, The Netherlands
| | - Arjen Amelink
- Netherlands Organisation for Applied Scientific Research TNO, Department of Optics, Delft, The Netherlands
| | - Johannes F de Boer
- Vrije Universiteit Amsterdam, LaserLaB, Department of Physics and Astronomy, Amsterdam, The Netherlands
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Vienola KV, Damodaran M, Braaf B, Vermeer KA, de Boer JF. In vivo retinal imaging for fixational eye motion detection using a high-speed digital micromirror device (DMD)-based ophthalmoscope. BIOMEDICAL OPTICS EXPRESS 2018; 9:591-602. [PMID: 29552396 PMCID: PMC5854061 DOI: 10.1364/boe.9.000591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 12/14/2017] [Accepted: 12/19/2017] [Indexed: 05/04/2023]
Abstract
Retinal motion detection with an accuracy of 0.77 arcmin corresponding to 3.7 µm on the retina is demonstrated with a novel digital micromirror device based ophthalmoscope. By generating a confocal image as a reference, eye motion could be measured from consecutively measured subsampled frames. The subsampled frames provide 7.7 millisecond snapshots of the retina without motion artifacts between the image points of the subsampled frame, distributed over the full field of view. An ophthalmoscope pattern projection speed of 130 Hz enabled a motion detection bandwidth of 65 Hz. A model eye with a scanning mirror was built to test the performance of the motion detection algorithm. Furthermore, an in vivo motion trace was obtained from a healthy volunteer. The obtained eye motion trace clearly shows the three main types of fixational eye movements. Lastly, the obtained eye motion trace was used to correct for the eye motion in consecutively obtained subsampled frames to produce an averaged confocal image correct for motion artefacts.
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Affiliation(s)
- Kari V. Vienola
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, HV Amsterdam, The Netherlands
| | - Mathi Damodaran
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, HV Amsterdam, The Netherlands
| | - Boy Braaf
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, HV Amsterdam, The Netherlands
| | - Koenraad A. Vermeer
- Rotterdam Ophthalmic Institute, Schiedamse Vest 160D, 3011 BH Rotterdam, The Netherlands
| | - Johannes F. de Boer
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, HV Amsterdam, The Netherlands
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