Transient interference gratings and holograms in dyed plastic

1984 ◽  
Vol 62 (7) ◽  
pp. 669-673
Author(s):  
Sergio Calixto ◽  
R. A. Lessard
Keyword(s):  
Real Time ◽  
Diffraction Efficiency ◽  
Laser Light ◽  
Thick Layer ◽  
Double Exposure ◽  
Naked Eye ◽  
Sufficient Intensity ◽  
Exposure Holography ◽  
Reading Beam ◽  
Made In

Transient diffraction gratings were holographically made in dyed plastic by absorbing laser light. Mean energy values of 40 mJ/cm2 absorbed in a 3-mm thick layer were needed to make gratings that lasted about 10 s. The writing beams and a reading one of different wavelength were simultaneously made to fall on the plastic: the reading beam was diffracted by the grating, which produced transient diffracted beams of sufficient intensity to be seen by the naked eye or to be stored permanently by conventional photographic methods. Curves showing diffraction efficiency versus exposure with grating frequency as a parameter are presented. Applications to real-time single and double exposure holography are also discussed.

scholarly journals A Deterministic Rapid Intensification Aid

2011 ◽  
Vol 26 (4) ◽  
pp. 579-585 ◽  
Author(s):  
Charles R. Sampson ◽  
John Kaplan ◽  
John A. Knaff ◽  
Mark DeMaria ◽  
Chris A. Sisko
Keyword(s):  
Real Time ◽  
Arithmetic Mean ◽  
Forecast Errors ◽  
Rapid Intensification ◽  
Intensity Forecast ◽  
Probability Threshold ◽  
Forecast Time ◽  
National Hurricane Center ◽  
Made In

Abstract Rapid intensification (RI) is difficult to forecast, but some progress has been made in developing probabilistic guidance for predicting these events. One such method is the RI index. The RI index is a probabilistic text product available to National Hurricane Center (NHC) forecasters in real time. The RI index gives the probabilities of three intensification rates [25, 30, and 35 kt (24 h)−1; or 12.9, 15.4, and 18.0 m s−1 (24 h)−1] for the 24-h period commencing at the initial forecast time. In this study the authors attempt to develop a deterministic intensity forecast aid from the RI index and, then, implement it as part of a consensus intensity forecast (arithmetic mean of several deterministic intensity forecasts used in operations) that has been shown to generally have lower mean forecast errors than any of its members. The RI aid is constructed using the highest available RI index intensification rate available for probabilities at or above a given probability (i.e., a probability threshold). Results indicate that the higher the probability threshold is, the better the RI aid performs. The RI aid appears to outperform the consensus aids at about the 50% probability threshold. The RI aid also improves forecast errors of operational consensus aids starting with a probability threshold of 30% and reduces negative biases in the forecasts. The authors suggest a 40% threshold for producing the RI aid initially. The 40% threshold is available for approximately 8% of all verifying forecasts, produces approximately 4% reduction in mean forecast errors for the intensity consensus aids, and corrects the negative biases by approximately 15%–20%. In operations, the threshold could be moved up to maximize gains in skill (reducing availability) or moved down to maximize availability (reducing gains in skill).

Investigation on dynamic holographic display in liquid crystal film doped with carbon dots

2020 ◽  
Vol 10 (6) ◽  
pp. 780-787
Author(s):  
Hongyue Gao ◽  
Suna Li ◽  
Jicheng Liu ◽  
Wen Zhou ◽  
Fan Xu ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Electric Field ◽  
Real Time ◽  
Diffraction Efficiency ◽  
Carbon Dots ◽  
Applied Electric Field ◽  
Light Polarization ◽  
Forming Process ◽  
Time Dynamic ◽  
Holographic Display

In this paper, we studied the holographic properties of liquid crystal (LC) thin film doped with carbon dots (CDs) which can be used as real-time holographic display screen. The maximum value of diffraction efficiency can reach up to 30% by using a low applied electric field 0.2 V/μm. Holograms in the LC film can be dynamically formed and self-erased. The hologram build-up time and the hologram self-erasure time in the material is fast enough to realize video refresh rate. In addition, the forming process of hologram was studied. The holographic diffraction efficiency was measured depending on the intensity of recording light, applied electric field, the intensity of readout light, and readout light polarization direction. Triple enhancement of the diffraction efficiency value by the modulation of voltage under the condition of low recording energy is presented. Therefore, we develop an easy way to obtain real-time dynamic holographic red, green and blue displays with high diffraction efficiency, which allow the LC film doped with CDs to be used as a holographic 3D display screen.

Holographic Evaluation of Edge Delamination in Bars Bonded to a Rigid Support With Foam-Adhesive

1996 ◽  
Vol 118 (3) ◽  
pp. 330-334 ◽  
Author(s):  
S. Qin ◽  
H. M. Shang ◽  
C. L. Giam ◽  
C. E. Tee
Keyword(s):  
Theoretical Analysis ◽  
Rapid Detection ◽  
Iterative Procedure ◽  
Point Load ◽  
Nonlinear Relationship ◽  
Rigid Support ◽  
Double Exposure ◽  
Simple Method ◽  
Exposure Holography ◽  
Edge Delamination

When a bar having one end bonded to a rigid support with foam-adhesive is loaded, the high peeling stresses at the bonded edge foster edge delamination along the interface of bonding. Upon inspection by double exposure holography, with an incremental point load applied at the free end of the bar between exposures, the indistinct fringe perturbation and the unknown resilience of the foam-adhesive (quantified by its foundation modulus) impede unambiguous evaluation of the condition of adhesion. This paper describes a simple method for rapid detection and assessment of artificially created edge delamination in such bar structures. The theoretical analysis elucidates the suitability of modelling the bar as partially clamped, and having an equivalent slope at its support related to the foundation modulus. Two dimensionless parameters are defined, which have between them a linear relationship for a nondelaminated bonding but a nonlinear relationship for a delaminated one. Finally, a simple iterative procedure is described for estimating the delaminated length without having to predetermine the elasticity of the support.

Automatic analysis of knee ligaments using double exposure holography

1991 ◽  
Vol 24 (6) ◽  
pp. 489
Author(s):  
Huang Zhi ◽  
Torsten Wredmark ◽  
Ulrik Willers ◽  
Ingegerd Dirtoft ◽  
Rolf B Johansson
Keyword(s):  
Automatic Analysis ◽  
Double Exposure ◽  
Knee Ligaments ◽  
Exposure Holography

A Window Based Graphical User Interface for a Supersonic Combustion Fortran Code

1992 ◽  
Author(s):  
T. Gary Yip ◽  
Ajay R. Patel
Keyword(s):  
Real Time ◽  
Input Sequence ◽  
Supersonic Combustion ◽  
Input File ◽  
Input Interface ◽  
Wide Acceptance ◽  
Fortran Code ◽  
Questions And Answers ◽  
Application Programs ◽  
Made In

Abstract Fortran has been used widely in number crunching applications. In recent years, as the size of application programs increases significantly, users begin to demand interactive capability so that they can interface with the applications in real time in a more flexible and convenient manner. In spite of the wide acceptance by engineers in various fields in the seventies and eighties, Fortran currently does not offer these features. INPUT/OUTPUT are structured rigidly by the order of the READ and WRITE statements in the application programs. The situation would get even worse when the program requires a large number of inputs from the user. A user can use a large input file in which the data must be in a fixed format and no comment statements are allowed. An alternative is to write a real time input interface with requests for inputs displayed on the screen. This leads to a long list of questions and answers scrolling up the screen. When a mistake is made in answering any one of the questions, the input sequence has to be restarted at the beginning of the program again.

Light Field Microscope to Achieve Three-Dimensional Real-Time Naked-Eye Display

2012 ◽  
Vol 32 (10) ◽  
pp. 1022005
Author(s):  
戴志华 Dai Zhihua ◽  
徐于萍 Xu Yuping ◽  
步敬 Bu Jing ◽  
杨勇 Yang Yong ◽  
赵星 Zhao Xing ◽  
...  
Keyword(s):  
Real Time ◽  
Light Field ◽  
Three Dimensional ◽  
Naked Eye

Comparison of Three Display Methodologies for Battlefield Resource Management

1998 ◽  
Vol 42 (5) ◽  
pp. 476-480 ◽  
Author(s):  
Daniel N. Mountjoy ◽  
Celestine A. Ntuen ◽  
Philip L. Yarbrough
Keyword(s):  
Resource Management ◽  
Real Time ◽  
Complete Data ◽  
Timely Manner ◽  
Military Forces ◽  
Made In

As the Army prepares to move into the next century, it is exploring advances in technology that will enable U.S. military forces to obtain more complete data regarding its mission, enemy and friendly troop locations, weather, and target status. Not only will this data be more accurate, it will be collected and transmitted in near real-time. Advanced displays must be developed that allow commanders to efficiently deal with large volumes of data so that effective decisions can be made in a timely manner. This paper describes an experiment comparing three methods of displaying battlefield resources and unit mobility: (1) a combination of alphanumerics and standard Army decision graphics, (2) a configural display (CD) representation, and (3) an associative configural display representation (ACD). Results indicate that performance benefits are realized from both the CD and ACD representations, but the CD proved to be the best overall.

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