Off-axis digital holographic microscopy: practical design parameters for operating at diffraction limit

Sánchez-Ortiga, Emilio; Doblas, Ana; Saavedra, Genaro; Martı́nez-Corral, Manuel; Garcı́a-Sucerquia, Jorge

doi:10.1364/ao.53.002058

Cited by 128 publications

(80 citation statements)

References 23 publications

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“…However, our research group has recently demonstrated that the optical capture stage controls the accuracy of QPI-DHM. [5][6][7] Specifically, we showed that QPI-DHM operating in telecentric mode-producing a 2D image of a 3D object-provides very accurate diffraction-limited quantitative phase images with minimal post-processing. This accuracy can be very useful for the diagnosis of different diseases and for specimen identification.…”

mentioning

confidence: 89%

Digital holographic microscopy for diabetes screening

Doblas¹,

Martı́nez-Corral²,

Saavedra³

2016

SPIE Newsroom

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A digital holographic microscope operating in telecentric mode could be used to diagnose diabetes and evaluate long-term glycemic control in patients with diabetes.Transparent objects, such as live biological cells, are difficult to observe and quantify using traditional light microscopes owing to lack of contrast. However, recent advances in quantitative phase imaging (QPI) of transparent microscopic specimens using digital holographic microscopy (DHM) have facilitated observation of unstained living cells in ways that were previously impossible. This type of microscopy relies on the different optical densities of the specimen and surrounding medium, producing a difference in phase between the light passing through the specimen and the light passing through the medium, ultimately generating an interference pattern. In DHM, only a single recorded image is required to obtain the fringe pattern resulting from the interference between a reference wave and the image of the wavefront diffracted by the specimen. From the pattern, phase changes introduced by the specimen are easily retrieved to produce a quantitative phase map. These phase changes encode the information about the refractive index and thickness of the specimen and as a result, QPI-DHM can be used to analyze illnesses in which the refractive index and/or morphology of cells or tissues are distorted. [1][2][3][4] The application of QPI-DHM to medical diagnosis relies on the high accuracy of the phase map measurements. The optical capture and subsequent computational processing both have a significant role in this hybrid technique. However, our research group has recently demonstrated that the optical capture stage controls the accuracy of QPI-DHM. 5-7 Specifically, we showed that QPI-DHM operating in telecentric mode-producing a 2D image of a 3D object-provides very accurate diffraction-limited quantitative phase images with minimal post-processing. This accuracy can be very useful for the diagnosis of different diseases and for specimen identification. Here, we show how this type of microscopy can be used in the diagnosis of diabetes mellitus (DM), using a simple procedure that requires a small amount of blood.Telecentric DHM has a potential application as a technique for the screening of DM, 8 which is undoubtedly one of the most challenging health problems of this century. Assessment and control of hyperglycemic states is one of the main methods of minimizing the risk of developing the medical complications associated with DM. Currently, the gold standard method to evaluate hyperglycemia in patients with DM and obtain long-term glycemic control is the determination of glycated hemoglobin (HbA1c) concentration. This measurement is usually made by high-performance liquid chromatography (HPLC), Continued on next page

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mentioning

confidence: 89%

Digital holographic microscopy for diabetes screening

Doblas¹,

Martı́nez-Corral²,

Saavedra³

2016

SPIE Newsroom

Self Cite

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“…Con el fin de poder seleccionar exclusivamente las frecuencias portadoras del orden +1, es necesaria una configuración fuera de eje donde los órdenes difractados puedan separarse por completo y no exista un solapamiento entre ellos. La ubicación de los órdenes difractados es controlada por el ángulo de incidencia que existe entre la onda de referencia y la onda objeto al incidir sobre el plano del medio de registro [23][24][25][26] según se ilustra en la Fig. 4.…”

Section: Análisis Teóricounclassified

Experimental study of the effects of the spatial filtering on off-axis digital holography operating out and in of the diffraction limit

2017

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Experimental study of the effects of the spatial filtering on off-axis digital holography operating out and in of the diffraction limitEstudio experimental de los efectos del filtrado espacial en holografía digital fuera de eje operando fuera o dentro en el límite de difracción ABSTRACT:This paper presents a theoretical and experimental analysis of the close relationship between the recording of digital holograms operating out or in of the diffraction limit and the spatial filtering process in the overall performance of the numerical reconstruction of the digitally recorded holograms. The results allow to conclude that it is not possible to make a correct spatial filtering for a reliable numerical reconstruction of the recorded holograms, if the recording is not made in the diffraction limit or presents overlapping of the diffraction orders.Key words: Digital holography, spatial filter, diffraction limit. RESUMEN:En este trabajo se hace un análisis teórico y experimental de la estrecha relación que existe entre el registro de hologramas digitales operando o no en el límite de difracción y del proceso de filtrado espacial en el desempeño global de la reconstrucción numérica de hologramas registrados digitalmente. Los resultados obtenidos permiten concluir que no es posible hacer un filtrado espacial correcto del holograma para su posterior reconstrucción numérica, si el registro de holograma no es realizado en el límite de difracción o en su defecto sin solapamiento de los órdenes de difracción.Palabras clave: Holografía digital, filtrado espacial, límite de difracción.

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“…A lowerresolution means that the field of view has to be reduced, and/or the magnification of the optical detection system (OBJ2, L4, OBJ3 and L5 in Fig. 2) should be reduced, leading to a smaller spatial frequency bandwidth [35]. The resolution of 800 by 800 pixels that we used is enough for fibers with a V number up to 350, e.g.…”

Section: Speedmentioning

confidence: 99%

Digital confocal microscopy through a multimode fiber

Loterie¹,

Farahi²,

Papadopoulos³

et al. 2015

Opt. Express

147

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Acquiring high-contrast optical images deep inside biological tissues is still a challenging problem. Confocal microscopy is an important tool for biomedical imaging since it improves image quality by rejecting background signals. However, it suffers from low sensitivity in deep tissues due to light scattering. Recently, multimode fibers have provided a new paradigm for minimally invasive endoscopic imaging by controlling light propagation through them. Here we introduce a combined imaging technique where confocal images are acquired through a multimode fiber. We achieve this by digitally engineering the excitation wavefront and then applying a virtual digital pinhole on the collected signal. In this way, we are able to acquire images through the fiber with significantly increased contrast. With a fiber of numerical aperture 0.22, we achieve a lateral resolution of 1.5µm, and an axial resolution of 12.7µm. The point-scanning rate is currently limited by our spatial light modulator (20Hz). wide-field endoscopic imaging by using a single multimode optical fiber," Phys.

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Off-axis digital holographic microscopy: practical design parameters for operating at diffraction limit

Cited by 128 publications

References 23 publications

Digital holographic microscopy for diabetes screening

Digital holographic microscopy for diabetes screening

Experimental study of the effects of the spatial filtering on off-axis digital holography operating out and in of the diffraction limit

Digital confocal microscopy through a multimode fiber

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