scholarly journals On the History, Presence, and Future of Optics Manufacturing

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 675
Author(s):  
Christoph Gerhard
Keyword(s):  

In 1850, Austen Henry Layard discovered an approximately 3000-year-old, simple optical lens in Nimrud, Northern Iraq—the Nimrud lens, aka the Layard lens [...]

Author(s):  
H. Rose

The imaging performance of the light optical lens systems has reached such a degree of perfection that nowadays numerical apertures of about 1 can be utilized. Compared to this state of development the objective lenses of electron microscopes are rather poor allowing at most usable apertures somewhat smaller than 10-2 . This severe shortcoming is due to the unavoidable axial chromatic and spherical aberration of rotationally symmetric electron lenses employed so far in all electron microscopes.The resolution of such electron microscopes can only be improved by increasing the accelerating voltage which shortens the electron wave length. Unfortunately, this procedure is rather ineffective because the achievable gain in resolution is only proportional to λ1/4 for a fixed magnetic field strength determined by the magnetic saturation of the pole pieces. Moreover, increasing the acceleration voltage results in deleterious knock-on processes and in extreme difficulties to stabilize the high voltage. Last not least the cost increase exponentially with voltage.


Author(s):  
Raymond A. Lee ◽  
Patrick J. Wolpert

Abstract FIB Micromachining has long been an established technique, but until recently it has been overshadowed by the more mainstream semiconductor application of the Focused Ion Beam system. Nano- Structure fabrication using the FIB system has become more popular recently due to several factors. The need for sub-micron structures have grown significantly due to a need for enhanced optical and biological applications. Another reason for the growth in micromachining is the improvement made in the ability of FIB systems to produce geometric shapes with high precision. With the latest high-end FIB systems, it is possible to produce microstructures with tens of nano-meters of precision. Optical lens, AFM tips, and nano-apertures are all part of the growing application for FIB Micromachining. This paper will discuss the ability and limitations of the FIB system and some possible application for FIB Micromachining.


2018 ◽  
Vol 144 (3) ◽  
pp. 637
Author(s):  
Naji Taha Said ◽  
Mustafa Cemal Çiftçi ◽  
Erdem Seven
Keyword(s):  

Paléorient ◽  
1989 ◽  
Vol 15 (1) ◽  
pp. 32-42 ◽  
Author(s):  
Stefan Karol Kozlowski ◽  
Karol Szymczak
Keyword(s):  

Hydrology ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 58
Author(s):  
Ahmed Naseh Ahmed Hamdan ◽  
Suhad Almuktar ◽  
Miklas Scholz

It has become necessary to estimate the quantities of runoff by knowing the amount of rainfall to calculate the required quantities of water storage in reservoirs and to determine the likelihood of flooding. The present study deals with the development of a hydrological model named Hydrologic Engineering Center (HEC-HMS), which uses Digital Elevation Models (DEM). This hydrological model was used by means of the Geospatial Hydrologic Modeling Extension (HEC-GeoHMS) and Geographical Information Systems (GIS) to identify the discharge of the Al-Adhaim River catchment and embankment dam in Iraq by simulated rainfall-runoff processes. The meteorological models were developed within the HEC-HMS from the recorded daily rainfall data for the hydrological years 2015 to 2018. The control specifications were defined for the specified period and one day time step. The Soil Conservation Service-Curve number (SCS-CN), SCS Unit Hydrograph and Muskingum methods were used for loss, transformation and routing calculations, respectively. The model was simulated for two years for calibration and one year for verification of the daily rainfall values. The results showed that both observed and simulated hydrographs were highly correlated. The model’s performance was evaluated by using a coefficient of determination of 90% for calibration and verification. The dam’s discharge for the considered period was successfully simulated but slightly overestimated. The results indicated that the model is suitable for hydrological simulations in the Al-Adhaim river catchment.


Iraq ◽  
2020 ◽  
Vol 82 ◽  
pp. 41-71
Author(s):  
Robert Carter ◽  
David Wengrow ◽  
Saber Ahmed Saber ◽  
Sami Jamil Hamarashi ◽  
Mary Shepperson ◽  
...  

The Shahrizor Prehistory Project has targeted prehistoric levels of the Late Ubaid and Late Chalcolithic 4 (LC4; Late Middle Uruk) periods at Gurga Chiya (Shahrizor, Kurdistan region of northern Iraq), along with the Halaf period at the adjacent site of Tepe Marani. Excavations at the latter have produced new dietary and environmental data for the sixth millennium B.C. in the region, while at Gurga Chiya part of a burned Late Ubaid tripartite house was excavated. This has yielded a promising archaeobotanical assemblage and established a benchmark ceramic assemblage for the Shahrizor Plain, which is closely comparable to material known from Tell Madhhur in the Hamrin valley. The related series of radiocarbon dates gives significant new insights into the divergent timing of the Late Ubaid and early LC in northern and southern Mesopotamia. In the following occupation horizon, a ceramic assemblage closely aligned to the southern Middle Uruk indicates convergence of material culture with central and southern Iraq as early as the LC4 period. Combined with data for the appearance of Early Uruk elements at sites in the adjacent Qara Dagh region, this hints at long-term co-development of material culture during the fourth millennium B.C. in southeastern Iraqi Kurdistan and central and southern Iraq, potentially questioning the model of expansion or colonialism from the south.


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