This paper proposes a new strategy of extracting boundary points from scanning point cloud (SPC) data of sheet metal parts (SMPs). This strategy is suitable for bending SMPs with slowly changing surfaces. To cope with the problem that the SMP is too thin to have enough points of its lateral surface to be calculated for the boundary outline, the boundary points are obtained by moving ridge points which is the maximum curvature points on the marginal of parts along theoretical position direction. In this article, the strategy is explained firstly and then carried out on two different experimental SMPs. The strategy contains several steps. Firstly, we construct a slice set called multiple direction slices (MDS) along a curve fitted by boundary points of SPC. Then marginal point data (MPD) is obtained completely and accurately by MDS. And then the chamfer arc data is extracted from MPD by setting identification model of chamfer arc’s two endpoints. Then the ridge points which are the maximal curvature points of chamfer arc data are picked out from chamfer arc data. Finally, by moving the ridge points along a certain direction for a fixed distance, the boundary points are calculated out. Two experiments are carried out to identify position error and form error of the extracted boundary points. The measurement results of boundary outlines of a 6mm thick SMP from a three coordinate measuring machine (CMM) is taken as reference in the first experiment. The second experiment regards theoretical boundary outline as reference. Both two experiments demonstrate the effectiveness of the strategy.
The aim of this work is to present a multi-band absorption metamaterials. One dual cross-shape perfect absorber
metamaterials (PAMs) was developed to obtain multi-band spectrum at mid-infrared. The PAMs possess three distinct
resonant peaks standing independently, which are attributed to the polarization sensitive excitation of plasmonic
resonance. The optical parameters retrieved by S-parameters method were investigated, which provides a satisfactory
qualitative description of the multiple-band spectra responses. On the other hand, the near-field plasmonic behaviors and
redistribution of the electromagnetic field were probed theoretically and numerically into the PAMs structure, which also
explains the observed absorption behavior of the PAMs ensemble based upon the microscopic perspective. The multiplex
spectrum enables the infrared perfect absorber metamaterials (PAMs) a powerful tool for direct access to vibrational
fingerprints of single molecular structure.
Optical antennas hold great promise for increasing the efficiency of photovoltaics, light-emitting devices, and optical sensors<sup>1</sup>. This paper discusses one strategy to achieve frequency selective detection at mid-infrared region, which utilize the plasmonic absorption nanoantenna. The infrared devices realized by such nanoantenna array have merits such as more flexibility of frequency selectivity, and its highlights of polarization properties, which will develop increased functionality for next generation focal plane arrays<sup>2</sup>. We investigated one example of such nanoantenna devices to tune its plasmonic resonance for achieving frequency selectivity and polarization properties. We also demonstrated its multiplex band absorption, and one tactics to broaden its absorption spectrum. The broad infrared sensitivity of nanoantenna devices would enable multiplex bands infrared imaging detectors. The optical properties of such examples are simulated and measurement which shows perfect absorption in certainty frequency-band. By exploiting nanoantenna as light-harvesting and carrier generation element, plasmonic absorption nanoantenna devices would realize both polarization- and wavelength-selective detection, which would overcome the band gap limitations of existing semiconducting materials.
The multiplex-bands absorption of sandwich-structure metamaterials based metal- dielectric- metal scheme are
investigated numerically and experimentally. The optical properties of cross-shape antenna perfect absorber metamaterials are demonstrated in mid-IR electromagnetic (EM) wave. The dual-band perfect absorber with polarization
independence is observed under normal incidence. In order to understand the EM properties of dual-band perfect absorber, the plasmonic excitation and the induced current distribution were clarified for both peaks. The simulation results clearly show that the absorption bands are independently governed by the size of each part of the patterned
nanostructure. The repositioning of two near-perfect absorption peaks possesses a linear relationship. This allows for a
flexible reconfigurability over the entire near-infrared regime. Furthermore, in order to obtain multiplex-bands spectral
absorption response, two cross-shape antennas are connected to form one dumbbell antenna. The three perfect-absorption peaks can be controlled by the individual dipole antenna elements in the conditions of polarization incident EM wave.