Displacement laser interferometry with sub-nanometer uncertainty

Development in industry is asking for improved resolution and higher accuracy in mechanical measurement. Together with miniaturization the demand for sub nanometer uncertainty on dimensional metrology is increasing rapidly. Displacement laser interferometers are used widely as precision displacement measuring systems. This thesis describes the error sources which should be considered when measuring with these systems with (sub-)nanometer uncertainty, along with possible methods to overcome these errors. Whenconsidering interferometricdisplacementmeasurementswithnanometer uncertainty over small distances (below 1 mm) the measurements are influenced by periodic deviations originating frompolarizationmixing. Inmeasurements with nanometer uncertainty over larger distances this errormay become negligible compared to errors introduced by the refractive index changes of the medium in which the measurement takes place. In order to investigate the effect of periodic deviations, models were developed and tested. A model based on Jones matrices enables the prediction of periodic deviations originating from errors in optical alignment and polarization errors of the components of the interferometer. In order to enable the incorporation of polarization properties of components used in interferometers, different measurement setups are discussed. Novel measurement setups are introduced to measure the polarization properties of a heterodyne laser head used in the interferometer system. Based on ellipsometry a setup is realized to measure the polarization properties of the optical components of the laser interferometer. With use of measurements carried out with these setups and the model it can be concluded that periodic deviations originating from different error sources can not be superimposed, as interaction exists whichmay cause partial compensation. To examine the correctness of the predicted periodic deviations an entire interferometer system was placed on a traceable calibration setup based on a Fabry-P´erot interferometer. This system enables a calibration with an uncertainty of 0,94 nm over a range of 300 µm. Prior to this measurement the polarization properties of the separate components were measured to enable a good prediction of periodic deviations with the model. The measurements compared to the model revealed a standard deviation of 0,14 nm for small periodic deviations and a standard deviation of 0,3 nm for periodic deviations viii 0. ABSTRACT with amplitudes of several nanometers. As a result the Jones model combined with the setups for measurement of the polarization properties form a practical tool for designers of interferometer systems and optical components. This tool enables the designer to choose the right components and alignment tolerances for a practical setup with (sub-)nanometer uncertainty specifications. A second traceable calibration setup based on a Fabry-P´erot cavity was developed and built. Compared to the existing setup it has a higher sensitivity, smaller range and improved uncertainty of 0,24 nm over a range of 1 µm, and 0,40 nm over a range of 6 µm. To improve the uncertainty of existing laser interferometer systems a new compensation method for heterodyne laser interferometerswas proposed. It is based on phase quadraturemeasurement in combination with a compensation algorithm based on Heydemann’s compensation which is used frequently in homodyne interferometry. The system enables a compensation of periodic deviations with an amplitude of 8 nm down to an uncertainty of 0,2 nm. From measurements it appears that ghost reflections occurring in the optical system of the interferometer cannot be compensated by this method. Regarding the refractive index of air three measurement methods were compared. The three empirical equations which can be found in literature, an absolute refractometer based on a commercial interferometer and a newly developed tracker system based on a Fabry-P´erot cavity. The tracker was tested to investigate the feasibility of the method for absolute refractometry with improved uncertainty. The developed tracker had a relative uncertainty of 8 ·10-10. The comparison revealed some temperature effectswhich cannot be explained yet. However the results of the comparison indicate that an absolute refractometer based on a Fabry-P´erot cavity will improve the uncertainty of refractive index measurement compared to existing methods

Influence of Tropical Climate Conditions on the Quality of Antihypertensive Drugs from Rwandan Pharmacies

The objective of this study was to assess the quality of antihypertensive drugs and to investigate the influence of tropical storage conditions. Drug content and in vitro dissolution tests were performed on 10 test formulations (from Rwanda) and 6 reference formulations (from Belgium or France) after purchase and after 6-month storage under long-term (25 +/- 2 degrees C and 60 +/- 5% relative humidity [RH]) and accelerated (40 +/- 2 degrees C and 75 +/- 5% RH) testing conditions. Twenty percent of test formulations were of substandard content at the time of purchase. After 6 months at accelerated testing conditions, 7 of 10 test formulations were substandard in content and 8 were substandard for the combined criteria of drug content and dissolution, whereas no reference drug became substandard. This study shows that, apart from some drugs being already substandard from purchase, accelerated testing conditions (simulating tropical climate) have deleterious effects on the majority of antihypertensive drug formulations found in the Rwandan market

Development of porous delivery systems for oral drug and vaccine administration

As porous materials (polymers, metals and ceramics) have many interesting physical and chemical properties, they have widespread applications in nearly every technology sector. Chapter 1 described the main biomedical application of cellular materials: the use of porous ceramics, polymers and/or metals as bone implants for structural purposes as well as for local drug delivery. Several manufacturing techniques for porous ceramics are reviewed and the drug release from these porous devices is described. Chapter 1 also summarizes the most important aspects of the manufacturing and formulation of conventional tablets and pellets since the overall aim of this research project was to evaluate the possible applications of porous tablets and pellets for oral drug delivery. More specifically the application of porous tablets for the manufacturing of tablets containing low-dosed drugs or drugs with limited compression properties were investigated as well as the possibilities offered by porous pellets for oral delivery of conventional drugs as well as vaccines

Challenging the Significance of the LALIA and the Justinianic Plague: A Reanalysis of the Archaeological Record

Summary: The Late Antique Little Ice Age (LALIA), and the Justinianic Plague, were recently suggested as the possible culprits for settlement contraction and population decline that supposedly occurred in the 6th c. CE. According to some who support this claim, these changes contributed to the weakening of this empire, which eventually led to the loss of vast territories and its defeat by the Persians and Arabs in the first half of the 7th c. CE. The assumptions that climate and plague had devastating impacts in the 6th c. CE are largely based on selected textual evidence, and archaeological evidence outside of the boundaries of the Eastern Roman Empire. As the current article will show, it seems that these assumptions are inherently incorrect as vast amounts of evidence, including archaeological survey data, settlement patterns, shipwreck analyses, pottery distribution in the Mediterranean and other material, indicate that there was no decline in the 6th c. CE. On the contrary, it is possible that there was a peak in population size in the second half of the 6th c. CE, suggesting that the LALIA and the Justinianic plague were limited in their impact

Japanese Newspapers' International Reporting: Case Study Israel 1973-91

This thesis aims at establishing the factors involved in the mainstream Japanese newspapers’ international news reporting process, and verifying their permanency through a case study of reporting on Israel from 1973 until 1991. In the process, disparity between the norms of Japanese and western mainstream media becomes evident. The first part of the thesis is devoted to uncovering critical influences on the process of international reporting in Japan, particularly, culture and its omnipresence in a variety of significantly important contexts. The way in which these influences affect international reporting is evaluated through a literature overview, particularly of foreign-policy related case studies, with the assessment’s findings further tested and confirmed by interviews with Japanese foreign correspondents posted in London between October 2001 and May 2002. The second part of the thesis focuses on verifying whether the identified influences and their manifestations in the processes of the mainstream Japanese newspapers’ international news reporting are of an enduring character. The period of reporting on Israel from 1973, prior to the outbreak of the first Oil crisis until the end of the Gulf Crisis of 1990-1991, has been selected to analyse whether, and to what extent Japan’s foreign policy changes towards the Middle East as a result of the Oil Crisis of 1973, exerted influence on the reporting for the next two decades. Two methods of content analysis of the three selected national newspapers, the Asahi, Yomiuri and the Mainichi, are employed; frame analysis measured quantitatively and used for all the selected articles, and qualitative content analysis for editorials. Both methods of analysis revealed that the influences of the Japanese contexts on international news reporting are enduring. Furthermore, the quantitatively measured frame analysis revealed that the media acted indeed as part of the ‘State’, as in Gramsci’s (1971) “Hegemony theory”, as well as reconfirming Entman’s (1993) insight on the implication of frames as a “challenge to democracy”. As to the qualitative editorial analysis, it complemented the frame analysis by unveiling the ubiquity of Japanese values and related morals and their disparities with western ones. Based on these findings, an alternative theory for analysing the Japanese mainstream media’s international reporting is offered. The two conspicuous features of the theory are that the democratic Libertarian model of the media is discarded as irrelevant, and that Japan’s national interests, as embodied in its foreign policies, are identified as critical factors in the shaping of international reporting

Identificatie en kwantificatie van Staphylococcus aureus enterotoxinen m.b.v. LC-MS/MS: een novel tool ter ondersteuning van de voedselveiligheid

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