Noise and aliases in off-axis and phase-shifting holography

We have compared the respective efficiencies of off-axis and phase-shifting holography in terms of noise and aliases removal. The comparison is made by analyzing holograms of an USAF target backlit with laser illumination, recorded with a charge-coupled device camera. We show that it is essential to remove the LO beam noise, especially at low illumination levels

USAF solar thermal applications overview

Process heat applications were compared to solar thermal technologies. The generic process heat applications were analyzed for solar thermal technology utilization, using SERI's PROSYS/ECONOMAT model in an end use matching analysis and a separate analysis was made for solar ponds. Solar technologies appear attractive in a large number of applications. Low temperature applications at sites with high insolation and high fuel costs were found to be most attractive. No one solar thermal technology emerges as a clearly universal or preferred technology, however,, solar ponds offer a potential high payoff in a few, selected applications. It was shown that troughs and flat plate systems are cost effective in a large number of applications

High numerical aperture holographic microscopy reconstruction with extended z range

An holographic microscopy reconstruction method compatible with high numerical aperture microscope objective (MO) up to NA=1.4 is proposed. After off axis and reference field curvature corrections, and after selection of the +1 grating order holographic image, a phase mask that transforms the optical elements of the holographic setup into an afocal device is applied in the camera plane. The reconstruction is then made by the angular spectrum method. The field is first propagated in the image half space from the camera to the afocal image of the MO optimal plane (plane for which MO has been designed) by using a quadratic kernel. The field is then propagated from the MO optimal plane to the object with the exact kernel. Calibration of the reconstruction is made by imaging a calibrated object like an USAF resolution target for different positions along $z$. Once the calibration is done, the reconstruction can be made with an object located in any plane $z$. The reconstruction method has been validated experimentally with an USAF target imaged with a NA=1.4 microscope objective. Near-optimal resolution is obtained over an extended range ($\pm 50~\mu$m) of $z$ locations

Holographic microscopy reconstruction in both object and image half spaces with undistorted 3D grid

We propose an holographic microscopy reconstruction method, which propagates the hologram, in the object half space, in the vicinity of the object. The calibration yields reconstructions with an undistorted reconstruction grid i.e. with orthogonal $x$, $y$ and $z$ axis and constant pixels pitch. The method is validated with an USAF target imaged by a $\times$60 microscope objective, whose holograms are recorded and reconstructed for different USAF locations along the longitudinal axis: -75 to +75 $\mu$m. Since the reconstruction numerical phase mask, the reference phase curvature and MO form an afocal device, the reconstruction can be interpreted as occurring equivalently in the object or in image half space

Integrating Knowledge: An MIT Story

This is the first in a series of articles addressing how SDM alumnus Luke Cropsey is integrating knowledge from various MIT resources and transferring it to his employer, the US Air Force (USAF). Cropsey represented the USAF as MIT's Lean Advancement Initiative (LAI) Fellow for the '07-'08 academic year, while completing his SDM degree. In this article, Cropsey outlines how he synthesized resources from four communities—LAI, the Systems Engineering Advancement Research Initiative, SDM, and the USAF—to come up with an overarching methodology for examining and addressing the complexities of integrating unmanned aircraft systems into the National Airspace Syste

40 Years of FOIA, 20 Years of Delay: Oldest Pending Freedom of Information Requests Date Back to the 1980s

Presents findings from the Knight Open Government Survey, which surveys government offices and agencies on the status of their public information requests, and finds that extensive backlogs persist

Integrating information from global systems : dealing with the "on- and off-ramps" of the information superhighway

Includes bibliographical references (p. 16-17).Supported by the MIT International Financial Services Research Center, the MIT Center for Coordination Science and the MIT Industrial Performance Center. Supported by the Advanced Research Projects Agency and USAF/Rome Laboratory under a USAF contract. F30602-93-C-0160Stuart E. Madnick

Review of Always at War: Organizational Culture in Strategic Air Command, 1946-62 by Melvin G. Deaile

Review of Always at War: Organizational Culture in Strategic Air Command, 1946-62 by Melvin G. Deaile