Maskless imaging of dense samples using pixel super-resolution based multi-height lensfree on-chip microscopy.

Lensfree in-line holographic microscopy offers sub-micron resolution over a large field-of-view (e.g., ~24 mm2) with a cost-effective and compact design suitable for field use. However, it is limited to relatively low-density samples. To mitigate this limitation, we demonstrate an on-chip imaging approach based on pixel super-resolution and phase recovery, which iterates among multiple lensfree intensity measurements, each having a slightly different sample-to-sensor distance. By digitally aligning and registering these lensfree intensity measurements, phase and amplitude images of dense and connected specimens can be iteratively reconstructed over a large field-of-view of ~24 mm2 without the use of any spatial masks. We demonstrate the success of this multi-height in-line holographic approach by imaging dense Papanicolaou smears (i.e., Pap smears) and blood samples

Spaceborne sensors (1983-2000 AD): A forecast of technology

A technical review and forecast of space technology as it applies to spaceborne sensors for future NASA missions is presented. A format for categorization of sensor systems covering the entire electromagnetic spectrum, including particles and fields is developed. Major generic sensor systems are related to their subsystems, components, and to basic research and development. General supporting technologies such as cryogenics, optical design, and data processing electronics are addressed where appropriate. The dependence of many classes of instruments on common components, basic R&D and support technologies is also illustrated. A forecast of important system designs and instrument and component performance parameters is provided for the 1983-2000 AD time frame. Some insight into the scientific and applications capabilities and goals of the sensor systems is also given

Cellular Dynamics and Three-Dimensional Refractive Index Distribution Studied with Quantitative Phase Imaging

We present in this PhD thesis work various applications of digital holographic microscopy (DHM), an imaging technique based on coherent illumination which enables the recovery of the full complex wavefront, i.e. the amplitude and phase of a wave field which interacted with a specimen. The possibility to retrieve the phase information with DHM allows to measure surfaces with nanometric accuracy, or to employ it as an endogenous quantitative signal to assess the morphology of biological specimens. The technique has been developed during the past fifteen years to reach nowadays a mature state, where it can be used routinely for metrology applications for example. We study in this work advanced applications by taking advantage of this technique, while focusing on a specific measurement method of DHM, namely the off-axis configuration, which makes it possible to measure the complex wave field with one-shot capability through spatial encoding, thus enabling real-time detection. In a first part, we develop mathematical methods based on the fundamental model of holographic recording to suppress the so-called zero-order, which consists in intensity terms that coherent detection must suppress for complex wave retrieval. In the particular case of off-axis holography, the zero-order terms usually limit the spatial resolution because of the spatial encoding of the coherent signal. We first develop an iterative method which uses the fundamental relations between coherent and incoherent detection, in order to gradually suppress the zero order terms. In a second stage, we develop a non-iterative filtering method, based on nonlinear operators. The technique is based on the transfer to another filtering space through the use of the logarithm, and enables intrinsic suppression of the zero-order terms. Both methods present the advantage of not relying on any approximation, and are thus general for any off-axis holographic configuration. We show their applicability on various hologram types, and demonstrate that in the context of microscopy, their use can increase the spatial resolution of holography, in order to reach diffraction-limited imaging for any magnification. In a second part, we study potential applications of three-dimensional imaging through coherent detection by employing multiple acquisitions with a new scanning method. The coupling of tomographic reconstruction and quantitative phase imaging showed great potential in various published works, yielding to quantitative 3D refractive index distribution measured within biological specimens, and super-resolution imaging through synthetic aperture formalism. These methods are however still subjects to many issues, in particular due to practical limitations such as mechanical imprecision in the measurement protocols and the availability of flexible reconstruction algorithms. We study a new data acquisition method which eliminates the necessity of any scanning of the illumination pattern or object rotation during the acquisition, providing potentially a more stable acquisition protocol. We present results proving the principle of our approach by measuring the 3D refractive index distribution of pollen grain. In a third part, we applied DHM to the analysis of cell morphology and dynamics, applied in particular to neuronal cells. We couple the phase measurement with widely assessed methods such as dye probing or quantitative wide field fluorescence, in order to derive relevant biological indicators from DHM. Through the interpretation of the phase as an indicator of cell volume regulation, we derive criteria for early label-free cell death detection, where we show that cell monitoring with DHM makes it possible to detect cell non-viability at early stage by measuring deregulation mechanisms. We compare our methods with dyes for cell viability assessment, showing that DHM can detect cell death typically hours before usual dye probing procedures. We also couple the phase signal with intracellular ionic concentration imaging through fluorescence, showing that the phase measured on neuron cultures is intimately linked with ionic homeostasis and in particular transmembrane water movements accompanying ionic currents such as Ca2+ or Na+. We derive typical phase signatures related to the well-known Ca2+ bursts occurring during action potentials in neurons through stimulation with glutamate, one of the major neurotransmitters in the central nervous system

NASA Small Business Innovation Research Program. Composite List of Projects, 1983 to 1989

The NASA SBIR Composite List of Projects, 1983 to 1989, includes all projects that have been selected for support by the Small Business Innovation Research (SBIR) Program of NASA. The list describes 1232 Phase 1 and 510 Phase 2 contracts that had been awarded or were in negotiation for award in August 1990. The main body is organized alphabetically by name of the small businesses. Four indexes cross-reference the list. The objective of this listing is to provide information about the SBIR program to anyone concerned with NASA research and development activities

30 años (1977-2007): Centro de Investigaciones Ópticas (CIOp)

La edición de este libro fue financiada en parte por la Comisión de Investigaciones Científicas de la Provincia de Buenos Aires

Endoscopic Laser Speckle Contrast Analysis for Tissue Perfusion

Laser speckle contrast analysis (LASCA), as a method of measuring blood flow speed and tissue perfusion, is a full field imaging technique requiring simple configurations and data processing, which is important for the application in real time in vivo. But LASCA is sensitive to changes in environmental factors. The application in vivo is also limited to superficial detection due to the limitation of the light penetration depth. Therefore this thesis aims to develop an endoscopic LASCA system to extend the access to internal detection and explore the relationship between the contrast and experimental parameters. Firstly the relationship between the contrast and speckle size, flow mode, quantity of stationary scatterers and the signal intensity were investigated. Theoretical models for the relationship between the contrast and the mean intensity of the speckle pattern were deduced and the correction methods were introduced to correct the contrast bias due to the intensity difference. Then a flexible single wavelength endoscopic laser speckle contrast analysis system (ELASCA) was developed using a leached fibre image guide (LFIG). A Butterworth filter and defocus were used to remove the fibre pattern to retrieve the contrast images. This system and the data processing methods were used on a customized phantom demonstrating that this ELASCA system can detect the flow speed changes in an imaging domain. Afterwards a dual-wavelength ELASCA was developed for functional imaging of the blood circulation. The test on a human fingertip and rabbit uterine blood vessels show that this system can monitor the change of blood flow speed and the oxygen saturation introduced by occlusion, in addition to the cardiac pulse and respiration rate. Then a novel application of LASCA to visualize the ultrasound pressure field and the propagation of the shear wave is presented for the application of locating area of interest (AOI) and detecting tissue variation

Aeronautical engineering: A cumulative index to a continuing bibliography (supplement 274)

This publication is a cumulative index to the abstracts contained in supplements 262 through 273 of Aeronautical Engineering: A Continuing Bibliography. The bibliographic series is compiled through the cooperative efforts of the American Institute of Aeronautics and Astronautics (AIAA) and the National Aeronautics and Space Administration (NASA). Seven indexes are included: subject, personal author, corporate source, foreign technology, contract number, report number, and accession number