Search results for "Digital holographic microscopy"
showing 10 items of 55 documents
Spatially multiplexed interferometric microscopy: from basic principles to advanced arrangements
2019
La posibilidad de visualizar y analizar objetos microscópicos transparentes de una manera no invasiva ha sido uno de los principales retos de la microscopía óptica a lo largo del siglo XX. Para ello, se desarrollaron diversas técnicas de microscopía que convertían las variaciones en el índice de refracción de los objetos en variaciones de intensidad, haciendo estos objetos visibles a simple vista, entre las que destacan la microscopía de contraste de fase de Zernike o de contraste diferencial de Nomarski. Sin embargo, estas técnicas solamente proporcionan información cualitativa del objeto, por lo que su análisis se limita a la simple visualización. Por otro lado, existen otras técnicas de …
Automatic fringe pattern enhancement using truly adaptive period-guided bidimensional empirical mode decomposition.
2020
Fringe patterns encode the information about the result of a measurement performed via widely used optical full-field testing methods, e.g., interferometry, digital holographic microscopy, moiré techniques, structured illumination etc. Affected by the optical setup, changing environment and the sample itself fringe patterns are often corrupted with substantial noise, strong and uneven background illumination and exhibit low contrast. Fringe pattern enhancement, i.e., noise minimization and background term removal, at the pre-processing stage prior to the phase map calculation (for the measurement result decoding) is therefore essential to minimize the jeopardizing effect the mentioned error…
Spatially-multiplexed interferometric microscopy (SMIM): converting a standard microscope into a holographic one
2014
We report on an extremely simple, low cost and highly stable way to convert a standard microscope into a holographic one. The proposed architecture is based on a common-path interferometric layout where the input plane is spatially-multiplexed to allow reference beam transmission in a common light-path with the imaging branch. As consequence, the field of view provided by the layout is reduced. The use of coherent illumination (instead of the broadband one included in the microscope) and a properly placed one-dimensional diffraction grating (needed for the holographic recording) complete the experimental layout. The proposed update is experimentally validated in a regular Olympus BX-60 upri…
Digital holographic microscopy as a screening technology for diabetes
2019
Label-free quantitative phase imaging (QPI) is the hallmark of digital holographic microscopy (DHM). One of the most interesting medical applications of QPI-DHM is that it can be used to analyze illnesses in which the refractive index or/and the morphology of cells/tissues are distorted, from the acquisition of a single image. In this contribution, we obtain the phase maps of red blood cells (RBCs) samples of patients suffering from diabetes mellitus type 1 (DM1) by using a DHM. Our experimental results show that the measured phase values are significantly different between control non-diabetic and diabetic patients. The high correlation coefficient between the phase and the glycated hemogl…
Digital holographic microscopy with pure-optical spherical phase compensation
2011
Telecentric architecture is proposed for circumventing, by the pure-optical method, the residual parabolic phase distortion inherent to standard configuration of digital holographic microscopy. This optical circumvention produces several important advantages. One is that there is no need for computer compensation of the parabolic phase during the phase map recovering procedure. The other is that in off-axis configuration, the spatial frequency useful domain is enlarged. The validity of the method is demonstrated by performing quantitative measurement of depth differences with high axial resolution. (C) 2011 Optical Society of America
Digital holographic microscopy for diabetes screening
2016
A digital holographic microscope operating in telecentric mode could be used to diagnose diabetes and evaluate long-term glycemic control in patients with diabetes.
Coherent Microscopy for 3-D Movement Monitoring and Super-Resolved Imaging
2010
In this chapter we present three types of microscopy-related configurations while the first one is used for 3-D movement monitoring of the inspected samples, the second one is used for super-resolved 3-D imaging, and the last one presents an overview digital holographic microscopy applications. The first configuration is based on temporal tracking of secondary reflected speckles when imaged by properly defocused optics. We validate the proposed scheme by using it to monitor 3-D spontaneous contraction of rat’s cardiac muscle cells while allowing nanometric tracking accuracy without interferometric recording. The second configuration includes projection of temporally varying speckle patterns…
Study of spatial lateral resolution in off-axis digital holographic microscopy
2015
The lateral resolution in digital holographic microscopy (DHM) has been widely studied in terms of both recording and reconstruction parameters. Although it is understood that once the digital hologram is recorded the physical resolution is fixed according to the diffraction theory and the pixel density, still some researches link the resolution of the reconstructed wavefield with the recording distance as well as with the zero-padding technique. Aiming to help avoiding these misconceptions, in this paper we analyze the lateral resolution of DHM through the variation of those two parameters. To support our outcomes, we have designed numerical simulations and experimental verifications. Both…
Superresolved Holographic Microscopy
2008
Superresolution methods in digital holographic microscopy provide a useful tool to overcome the Abbe's diffraction limit when using modest microscope lenses. The process improves the cutoff frequency of the microscope lens by means of the generation of a synthetic aperture based on time multiplexing and using 3 main stages: optical coding, optical decoding, and digital postprocessing. After the whole process, a superresolved image is obtained by Fourier transformation of the synthetic aperture.
Superesolution in digital holographic microscopy
2011
In this contribution, we address with the possibility to overcome the limited resolving power of imaging systems beyond the limit imposed by Abbe's diffraction theory. We first review the mathematical foundations underlying superresolution (SR) from an information theory point of view and then we focus on two multiplexing approaches in digital holographic microscopy (DHM) for achieving SR by synthetic aperture (SA) generation.