Browsing by Subject "Crosstalk"

Now showing 1 - 5 of 5

Open Access
High-efficiency low-crosstalk dielectric metasurfaces of mid-wave infrared focal plane arrays
(American Institute of Physics Inc., 2017) Akın, O.; Demir, Hilmi Volkan
High-resolution compact-size focal plane arrays (FPAs) suffer the fundamental geometrical tradeoff between the optical resolution (pixel size miniaturization) and the optical crosstalk (spillover of neighboring pixel focusing). For FPAs, our previously reported metallic metasurfaces reached an unprecedented level of crosstalk suppression. However, practical utilization of these metallic microlens arrays has proved to be intrinsically limited due to the low device efficiency (of the order of 0.10) resulting from the fundamental absorption losses of metals and their cross-polarization scheme. Exceeding this limit, here we show highly efficient microlens designs enabled by dielectric metasurfaces for mid-wave infrared (MWIR) operation. These dielectric MWIR FPAs allow for a substantially high device efficiency over 0.80 without compromising the optical crosstalk performance. Systematically studying dielectric nanoantennas of silicon nanodisks that do not dictate the cross-polarization scheme using full-wave solutions, we found that the optical crosstalk is suppressed to low levels ≤ 3.0% while sustaining the high efficiency. A figure-of-merit (FoM) defined for the device performance as the focusing efficiency per optical crosstalk times the f-number achieves 84, which is superior to all other types of MWIR FPAs reported to date, all falling below a maximum FoM of 70. These findings indicate that the proposed approach can pave the way for the practical usage of metasurface microlens arrays in MWIR.
Open Access
Map building with multiple range measurements using morphological surface profile extraction
(IEEE, Piscataway, NJ, United States, 1999) Barshan, B.; Başkent, D.
A novel method is described for surface profile extraction based on morphological processing of multiple range sensor data. The approach taken is extremely flexible and robust, in addition to being simple and straightforward. It can deal with arbitrary numbers and configurations of range sensors as well as synthetic arrays. The method has the intrinsic ability to suppress spurious readings, crosstalk, and higher-order reflections, and process multiple reflections informatively. The essential idea of this work - the use of multiple range sensors combined with morphological processing - can be applied to different physical modalities of range sensing of vastly different scales and in many different areas. These may include radar, sonar, robotics, optical sensing and metrology, remote sensing, ocean surface exploration, geophysical exploration, and acoustic microscopy.
Open Access
Morphological surface profile extraction from multiple sonars
(IEEE, 1998) Başkent, Deniz; Barshan, Billur
This paper presents a novel method for surface profile determination using multiple sensors. Our approach is based on morphological processing techniques to fuse the range data from multiple sensor returns in a manner that directly reveals the target surface profile. The method has the intrinsic ability of suppressing spurious readings due to noise, crosstalk, and higher-order reflections, as well as processing multiple reflections informatively. The algorithm is verified both by simulations and experiments in the laboratory by processing real sonar data obtained from a mobile robot. The results are compared to those obtained from a more accurate structured-light system, which is however more complex and expensive.
Open Access
Noise analysis of flexing crossbars under the victim-aggresssor model
(2015-06) Erdemir, Sertaç
This study investigates the e ects of crosstalk noise on exing crossbars, and proposes an e cient method for estimation. The estimation method is also applicable to other submicron VLSI circuits. Circuit theory is utilized to estimate crosstalk emergence due to coupling e ects and means of crosstalk reduction are investigated. Peak crosstalk noise amplitude, occurrence time, and time domain waveform are represented in closed form expressions. This research also introduces an empirical approach to compute the best case victim-aggressor alignment that minimizes the crosstalk noise on victim lines. In addition, it suggests a geometric approach reducing the adverse e ects of crosstalk noise on exing crossbars. Delay and signal quality for varied lengths of interconnect wires on interconnection networks using lossy transmission line theory are analyzed and examined in detail. Furthermore, crossbar networks are compared with other interconnection networks in terms of power consumptions.
Open Access
Simultaneous measurement of multiple independent atomic-scale interactions using scanning probe microscopy: data interpretation and the effect of cross-talk
(American Chemical Society, 2015) Baykara, M. Z.; Todorović, M.; Mönig, H.; Schwendemann, T. C.; Rodrigo, L.; Altman, E. I.; Pérez, R.; Schwarz, U. D.
In high-resolution scanning probe microscopy, it is becoming increasingly common to simultaneously record multiple channels representing different tip-sample interactions to collect complementary information about the sample surface. A popular choice involves simultaneous scanning tunneling microscopy (STM) and noncontact atomic force microscopy (NC-AFM) measurements, which are thought to reflect the chemical and electronic properties of the sample surface. With surface-oxidized Cu(100) as an example, we investigate whether atomic-scale information on chemical interactions can be reliably extracted from frequency shift maps obtained while using the tunneling current as the feedback parameter. Ab initio calculations of interaction forces between specific tip apexes and the surface are utilized to compare experiments with theoretical expectations. The examination reveals that constant-current operation may induce a noticeable influence of topography-feedback-induced cross-talk on the frequency shift data, resulting in misleading interpretations of local chemical interactions on the surface. Consequently, the need to apply methods such as 3D-AFM is emphasized when accurate conclusions about both the local charge density near the Fermi level, as provided by the STM channel, and the site-specific strength of tip-sample interactions (NC-AFM channel) are desired. We conclude by generalizing to the case where multiple atomic-scale interactions are being probed while only one of them is kept constant.