NASA Scientific and Technical Aerospace Reports

therefore was intended to establish the wind geometry, kinematics and ionization state, both in a time-averaged sense and as
a function of time.
Derived from text
Cataclysmic Variables; Accretion Disks
20040111518 Naval Health Research Center, Brooks AFB, TX
Celebrating the Usefulness of Pictorial Information in Visual Perception
Beer, Jeremy; Jun. 29, 2004; 17 pp.; In English
Report No.(s): AD-A425514; No Copyright; Avail: CASI; A03, Hardcopy
This book is a collection of biographical essays describing the influence of Julian Hochberg, a leading researcher in vision
science and human performance modeling. In this chapter, Jeremy Beer, who was Hochberg’s doctoral student, describes three
areas in which Hochberg’s experimental approach remains influential in vision research. The first area comprises the
comparison of motion information versus pictorial depth cues (e.g., linear perspective, relative size) in moving viewers’
perception of distance and slant. Hochberg demonstrated that pictorial cues can overcome other sources of information to
determine how viewers will perceive a three-dimensional scene. These principles continue in the design of modern cockpit
displays incorporating features like ‘highway in the sky.’ The second area comprises the comparison of motion information
versus pictorial cues in the perception of time-to-collision. As in the first topic, recent work has demonstrated that pictorial
cues can dominate other kinds of information in important visually controlled tasks such as vehicle braking and interceptive
action. The third area comprises the effects of display boundaries on the perception of extended scenes. Recent work in this
field has determined that human operators perceive scenes according to a distorted geometry when the boundaries of the
display are restricted. (3 figures, 13 refs.)
DTIC
Display Devices; Graphic Arts; Visual Aids; Visual Perception
20040120851 Fermi National Accelerator Lab., Batavia, IL, USA
Stability Analysis of the Laser System for the TTF Photoinjector at Fermilab
Yang, X.; 2004; 14 pp.; In English
Report No.(s): DE2004-823675; FERMILAB-TM-2246; No Copyright; Avail: Department of Energy Information Bridge
A solid-state laser system that produces a 1MHz pulse train of 800 pulses with 18(micro)J per pulse at(lambda)= 263.5
nm has been developed to meet the requirements of the TESLA Test Facility (TTF) at Fermilab and in operation since 1998.
Besides the production of high charges, high brightness electron beams, the need for high bunch charge stability requires that
each laser pulse in the pulse train must have the same energy, and the energy per laser pulse should not vary significantly from
shot to shot. This motivates the stability analysis of the laser system for the TTF photoinjector.
NTIS
Solid State Lasers; Test Facilities; Stability Tests
20040120868 NASA Glenn Research Center, Cleveland, OH, USA
Information Content of the Near-Field I: Two-Dimensional Samples
Frazin, Richard A.; Fischer, David G.; Carney, P. Scott; January 2004; 26 pp.; In English
Contract(s)/Grant(s): NAG3-2764; NSF 02-39265; WBS 22-101-58-11; Copyright; Avail: CASI; A03, Hardcopy
Limits on the effective resolution of many optical near-field experiments are investigated. The results are applicable to
variants of total-internal-reflection microscopy (TIRM), photon-scanning-tunneling microscopy (PSTM), and near-fieldscanning-optical
microscopy (NSOM) in which the sample is weakly scattering and the direction of illumination may be
controlled. Analytical expressions for the variance of the estimate of the complex susceptibility of an unknown
two-dimensional object as a function of spatial frequency are obtained for Gaussian and Poisson noise models, and a
model-independent measure is examined. The results are used to explore the transition from near-zone to far-zone detection.
It is demonstrated that the information content of the measurements made at a distance of even one wavelength away from
the sample is already not much different from the information content of the far field. Copyright 2004 Optical Society of
America
Author
Microscopy; Near Fields; Signal Processing; Scattering; Two Dimensional Bodies
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