排序方式: 共有15条查询结果,搜索用时 15 毫秒
1.
L. K. Seah U. S. Dinish S. K. Ong Z. X. Chao V. M. Murukeshan 《Optics & Laser Technology》2004,36(5):371-376
Imaging of latent fingerprints using time-resolved (TR) method offers a broader platform to eliminate the unwanted background emission. In this paper, a novel TR imaging technique is demonstrated and implemented, which facilitates the detection of latent fingerprints with nanosecond resolution. Simulated experiments were carried out with two overlapping fingerprints treated with two fluorescent powders having different lifetimes in nanosecond range. The dependence of the fluorescence emission intensity in nanosecond resolution of TR imaging is also revealed. 相似文献
2.
We use tools of the equilibrium statistical mechanics of disordered systems to study analytically the statistical properties of an ecosystem composed of N species interacting via random mutual interactions, as well as via deterministic self-interactions of order p>/=2. We show that the main effect of increasing the order of the interactions among the species is to make the system less competitive, in the sense that the fraction of extinct species is greatly reduced. In addition, we find that for p>2 there is a threshold value which gives a lower bound to the concentration of the surviving species, preventing then the existence of rare species and, consequently, increasing the robustness of the ecosystem to external perturbations. 相似文献
3.
V. M. Murukeshan Ng Chee Keong Krishnakumar. V Ong Lin Seng A. Asundi 《Optics & Laser Technology》2001,33(5):919
This paper presents a double shearographic configuration based on the optical method by using two Michelson interferometers in tandem. The problems associated with the extraction of second order derivatives by optical means and a comparison with the proposed novel approach by digital means are discussed in this paper. 相似文献
4.
Z.X. Chao L.K. Seah V.M. Murukeshan U.S. Dinish C.S. Tan 《Optics & Laser Technology》2007,39(4):864-870
In this paper, a novel configuration of an integrated phase-resolved (PR) fingerprint fluorescence imaging system is proposed and implemented. In this integrated PR imaging system, a current modulated 402 nm dual diode laser is proposed to be the light source, to obtain both high laser power and easy modulability. To estimate the lifetime resolution of this PR imaging system, a novel method of using distance-selective suppression of fluorescence signals from two identical fluorescing samples is proposed. Detailed theoretical and experimental analyses are presented. The experimental results demonstrate that this integrated PR imaging system has a lifetime resolution of 0.1 ns. Fingerprint detection experiments are also carried out using this system with latent fingerprints deposited on substrates of aluminum foil and currency. 相似文献
5.
We present here a different and modified configuration in order to obtain the curvature fringes by incorporating phase shifting and image processing techniques. Optical fibers are used for obtaining shear fringes in which we have used Wollaston prism as the shear element. 相似文献
6.
K. V. Sreekanth V. M. Murukeshan 《Applied Physics A: Materials Science & Processing》2010,101(1):117-120
This paper describes and compares the effect of metal films, such as aluminum (Al) and silver (Ag) on UV-excited two-beam
surface plasmon interference nanolithography. A planar four-layer configuration has been employed to study the light intensity
distribution on the recording medium. It is observed that high-density sub-50 nm periodic structures were achievable by employing
the above-mentioned metal films when interrogated with p-polarized, 364 nm illumination wavelength source. It is found that
the obtained periodic feature shows good exposure depth and high contrast when Al is used as a metal film. The initial experimental
result of planar four-layer configuration is also presented. 相似文献
7.
This paper discusses and present simple wavefront interference concept, using multi facet prisms and UV laser, to pattern
periodic micro-features. Fabrication of square lattice features employing a biprism is illustrated. This concept is extended
employing three facet prisms to fabricate hexagonal lattice structures. These micro-features are expected to find tunable
photonic crystal applications.
Original Text ? Astro, Ltd., 2009.
The article is published in the original. 相似文献
8.
V. M. Murukeshan Lai Yin Fei V. Krishnakumar L. S. Ong A. Asundi 《Optics and Lasers in Engineering》2003,39(4):441-448
In interferometric fringe pattern analysis, specular and speckle fringe patterns are the two main divisions. While specular fringes are characterized by quality fringes, speckle (that obtains due to the diffuse scattering of the coherent radiation from an optically rough surface) fringe patterns are characterized by noisy fringes. This paper concentrates on this aspect and the Matlab based filtering methods to improve the quality of speckle fringe patterns by developing the appropriate software. Further, the newly developed software “Macurv” will be presented which can give the second order derivative (curvature) fringe information. A software with several functions is written using Matlab. The objective of the software is to provide a more effective way for the post-processing of speckle interferometric fringes. The algorithm and functions of the developed software “Macurv” will be explained. 相似文献
9.
Allison M Fox Mike Anderson Corinne Reid Tim Smith Dorothy VM Bishop 《BMC neuroscience》2010,11(1):1-15
Background
We examined development of auditory temporal integration and inhibition by assessing electrophysiological responses to tone pairs separated by interstimulus intervals (ISIs) of 25, 50, 100, 200, 400, and 800 ms in 28 children aged 7 to 9 years, and 15 adults.Results
In adults a distinct neural response was elicited to tones presented at ISIs of 25 ms or longer, whereas in children this was only seen in response to tones presented at ISIs above 100 ms. In adults, late N1 amplitude was larger for the second tone of the tone pair when separated by ISIs as short as 100 ms, consistent with the perceptual integration of successive stimuli within the temporal window of integration. In contrast, children showed enhanced negativity only when tone pairs were separated by ISIs of 200 ms. In children, the amplitude of the P1 component was attenuated at ISIs below 200 ms, consistent with a refractory process.Conclusions
These results indicate that adults integrate sequential auditory information into smaller temporal segments than children. These results suggest that there are marked maturational changes from childhood to adulthood in the perceptual processes underpinning the grouping of incoming auditory sensory information, and that electrophysiological measures provide a sensitive, non-invasive method allowing further examination of these changes. 相似文献10.
We demonstrate a novel multifunctional optical system that is capable of trapping, imaging, position sensing, and fluorescence detection of micrometer-sized fluorescent test particles using hollow-core photonic crystal fiber (HC-PCF). This multifunctional optical system for trapping, position sensing, and fluorescent detection is designed such that a near-IR laser light is used to create an optical trap across a liquid-filled HC-PCF, and a 473 nm laser is employed as a source for fluorescence excitation. This proposed system and the obtained results are expected to significantly enable an efficient integrated trapping platform employing HC-PCF for diagnostic biomedical applications. 相似文献