Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userHeterodyne holographic microscopy of gold particles
164
0
0.0
(
0
)
Authors
Michael Atlan
Ask ChatGPT about the research
No Arabic abstract
We report experimental results on heterodyne holographic microscopy of subwavelength-sized gold particles. The apparatus uses continuous green laser illumination of the metal beads in a total internal reflection configuration for dark-field operation. Detection of the scattered light at the illumination wavelength on a charge-coupled device array detector enables 3D localization of brownian particles in water
rate research
Read More
We use digital holographic microscopy and Mie scattering theory to simultaneously characterize and track individual colloidal particles. Each holographic snapshot provides enough information to measure a colloidal spheres radius and refractive index to within 1%, and simultaneously to measure its three-dimensional position with nanometer in-plane precision and 10 nanometer axial resolution.
Polarized light microscopy provides high contrast to birefringent specimen and is widely used as a diagnostic tool in pathology. However, polarization microscopy systems typically operate by analyzing images collected from two or more light paths in different states of polarization, which lead to relatively complex optical designs, high system costs or experienced technicians being required. Here, we present a deep learning-based holographic polarization microscope that is capable of obtaining quantitative birefringence retardance and orientation information of specimen from a phase recovered hologram, while only requiring the addition of one polarizer/analyzer pair to an existing holographic imaging system. Using a deep neural network, the reconstructed holographic images from a single state of polarization can be transformed into images equivalent to those captured using a single-shot computational polarized light microscope (SCPLM). Our analysis shows that a trained deep neural network can extract the birefringence information using both the sample specific morphological features as well as the holographic amplitude and phase distribution. To demonstrate the efficacy of this method, we tested it by imaging various birefringent samples including e.g., monosodium urate (MSU) and triamcinolone acetonide (TCA) crystals. Our method achieves similar results to SCPLM both qualitatively and quantitatively, and due to its simpler optical design and significantly larger field-of-view, this method has the potential to expand the access to polarization microscopy and its use for medical diagnosis in resource limited settings.
We introduce a new modality for dynamic phase imaging in confocal microscopy based on synthetic optical holography. By temporal demultiplexing of the detector signal into a series of holograms, we record time-resolved phase images directly in the time domain at a bandwidth as determined by the photo detector and digitizer. We demonstrate our method by optical imaging of transient vibrations in an atomic force microscope cantilever with 100 ns time resolution, and observe the dynamic deformation of the cantilever surface after excitation with broadband mechanical pulses. Temporal Fourier transform of a single data set acquired in 4.2 minutes yields frequency and mode profile of all excited out-of-plane vibration modes with sub-picometer vertical sensitivity and sub-micrometer lateral resolution. Our method has the potential for transient and spectroscopic vibration imaging of micromechanical systems at nano- and picosecond scale time resolution.
Multifocal plane microscopy (MUM) allows three dimensional objects to be imaged in a single camera frame. Our approach uses dual orthogonal diffraction phase gratings with a quadratic distortion of the lines to apply defocus to the first diffraction orders which, when paired with a relay lens, allows for 9 focal planes to be imaged on a single camera chip. This approach requires a strong signal level to ensure sufficient intensity in the diffracted light, but has the advantage of being compact and straightforward to implement. As the microscope begins to focus deeper into the sample, aberrations caused by refractive index mismatch and inhomogeneity in the samples media have an adverse effect on the signals quality. In this paper, we investigate the image quality improvement brought by applying adaptive optics (AO) to multifocal plane microscopy. A single correction device (an 8x8 deformable mirror (DM)) is combined with an image-based AO control strategy to perform the correction of optical aberrations. We compare full end-to-end modelling results using an established numerical modelling system adapted for microscopy to laboratory results both on a test sample and on a number of biological samples. Finally, we will demonstrate that combining AO and MUM, we are able to improve the image quality of biological samples and provide a good correction throughout the volume of the biological sample.
Quantitative phase microscopy (QPM) has found significant applications in the field of biomedical imaging which works on the principle of interferometry. The theory behind achieving interference in QPM with conventional light sources such as white light and lasers is very well developed. Recently, the use of dynamic speckle illumination (DSI) in QPM has attracted attention due to its advantages over conventional light sources such as high spatial phase sensitivity, single shot, scalable field of view (FOV) and resolution. However, the understanding behind obtaining interference fringes in QPM with DSI has not been convincingly covered previously. This imposes a constraint on obtaining interference fringes in QPM using DSI and limits its widespread penetration in the field of biomedical imaging. The present article provides the basic understanding of DSI through both simulation and experiments that is essential to build interference optical microscopy systems such as QPM, digital holographic microscopy and optical coherence tomography. Using the developed theory of DSI we demonstrate its capabilities of using non-identical objective lenses in both arms of the interference microscopy without degrading the interference fringe contrast and providing the flexibility to use user-defined microscope objective lens. It is also demonstrated that the interference fringes are not washed out over a large range of optical path difference (OPD) between the object and the reference arm providing competitive edge over low temporal coherence light sources. The theory and explanation developed here would enable wider penetration of DSI based QPM for applications in biology and material sciences.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
