Search results for "Focal point"
showing 8 items of 8 documents
Focal waveforms with tunable carrier frequency using dispersive aperturing
2008
We introduce the concept of dispersive aperturing involving a beam truncation by hard-edge apertures where diameter of the processed beam changes upon frequency. Applied to focused waves, this procedure transforms power spectra at the focal point (and the surroundings). Waveforms at focus conserve pulse duration but carrier frequency may be altered substantially. In principle, some degrees of freedom allow carrier-frequency tuning at convenience.
Internationalization pathways of family SMEs:Psychic distance as a focal point
2010
Purpose: The purpose of this paper is to investigate how psychic distance affects the internationalization process, foreign market entry (FME), and entry mode choice of Finnish small and medium-sized family enterprises (family SMEs) operating in France. Design/methodology/approach: The paper reports findings from an in-depth case study covering four Finnish manufacturing family SMEs operating in the French market. The data were analyzed using the Uppsala model and distance creating and distance-bridging factors encountered in the FME to France. Findings: The findings reveal that the family SMEs mainly followed a sequential process and favored indirect entry modes before entering the French …
Optical performance of two new trifocal intraocular lenses: through-focus modulation transfer function and influence of pupil size
2013
Background To compare the in vitro optical quality of two new trifocal intraocular lenses at different focal points as a function of pupil size. Methods Two intraocular lenses having different design approaches were evaluated: the AT LISA tri 839MP with a trifocal diffractive design, and the FineVision, which combines two distinct apodized bifocal diffractive profiles resulting in three foci. A PMTF optical bench was used to assess the intraocular lenses' performance, and as optical quality metrics, the through-focus modulation transfer function was selected; that is, it was measured at 10 focal points and for four different apertures (2.0, 3.0, 3.75 and 4.5 mm). Results For both lenses, th…
Unconventional, efficient and flexible bifocal lens design by metalens and AFA beam combination
2019
In the field of metasurface-based light focusing, both convex metalenses with parabolic phase profile and autofocused Airy (AFA) beams play essential roles. AFA beam generation as a combination of two convergent mirrored Airy beams leaves the space between the two launched Airy profiles inefficient with zero amplitude transmission and constant phase distribution. In this paper, we propose using this inutile space as an independent metalens. We show that coincidence of the focal spot of the metalens to that of the AFA beam will increase the focusing intensity more than 24 percent at its focal point. It is shown that using the nonoperative space between the two launched Airy beams as an indep…
Modeling of energy transfer from the photon beam at an optical media
2004
Laser beam could be applied to act in optical media, to build different spatial images. The operation could be made direct by copying an image or through a C.D. The successive points could be realized with relatively high speed, like 103-105 points per second. Each point represents practically a machining operation done by the laser beam. In most cases, energy transfer is made not in a plane, but in a volume, and this requires moving the focal point in positions required by the image we want to create. This is a sequentially operation, made point by point following a definite order, but in the same time, because the image is spatially, we have to adapt also other parameters of the optical s…
Amplitude modulation technique for designing metalenses with apodized and enhanced resolution focal spots
2017
Abstract In this paper we show that engineering both phase and amplitude of the scattered light can be employed in designing metalenses with either higher resolution or apodized focal spots. C-shaped split-ring micro-resonators (CSRRs) with different geometrical parameters are selected to have a full control of amplitude and phase. While phase engineering is necessary for light focusing, amplitude modulation of the scattered wave can be applied to characterize the focal point properties such as resolution gain and sidelobe level. We show that both axial and transverse resolution improvement or apodization is possible in the far-field region by applying proper amplitude function. Amplitude m…
In vitro optical quality differences between multifocal apodized diffractive intraocular lenses.
2013
Purpose To compare the in vitro optical quality of multifocal apodized intraocular lenses (IOLs) at different focal points. Setting University of Valencia, Valencia, Spain. Design Experimental study. Methods The Acrysof Restor +3.0 diopter (D) multifocal IOL with 2 main foci (bifocal IOL) and the Finevision multifocal IOL with 3 main foci (trifocal IOL) were evaluated. The optical quality was quantified using the modulation transfer function (MTF) at 7 focal points and for 3.0 mm and 4.5 mm apertures. The through-focus MTF at 10 focal points of the IOLs was also recorded. Results For the 0.0 D and −2.5 D focal points, the bifocal IOL showed the highest MTF values for pupil sizes as well as …
Focal Points in Collective Free Improvisation
2013
OLLECTIVE FREE IMPROVISATION (herein abbreviated as CFI), while not a recent phenomenon in music (free jazz’s first experiments date from the late 1950s), remains under-studied. The extant literature either deals with political aspects (Carles and Comolli 2000) or tries to analyze the resulting music, using musicological tools (Jost 1994) or new concepts drawn from the complexity sciences (Borgo 2005). My research on CFI focuses on a cognitive approach, in order to understand the process of collective improvisation: 1 how a group of improvisers who do not know each other and are not using a common referent 2 (Pressing 1988) can answer the challenge of making music together. This paper deals…