Direct in situ GDD measurement in optical coating process

In the presented work a fast frequency domain measurement system to determine group delay (GD) and group delay dispersion (GDD) of optical coatings is proposed. The measurements are performed in situ directly on moving substrates during the thin film coating process. The method is based on a Michelson interferometer, which is equipped with a high power broad band light source and a fast spectrometer. Especially for the production of chirped mirrors it is advantageous to obtain group delay and group delay dispersion data of the last layers. This additional information allows for online corrections of coating errors to enhance the precision of complex interference filters for short pulse applications. © 2015 SPIE

Optimization of novel phase separating IBS process

During the last years, optical low loss components gained more and more industrial interest and led to novel approaches for the production in optical coating technology. The application of filtered deposition technologies promises a significant reduction of particle contamination. Usually, filtered techniques are applied in combination with processes which produce a high level of undesired particles, like the cathodic arc deposition. In the present contribution, a magnetic field filter is applied in combination with a high quality ion beam sputtering process. The focus of the investigation constitutes the modulation of the guiding process with respect to the guiding efficiency. Numerical investigations reveal the trajectories of the ions during the guiding process and allow to analyze the influence of the magnetic field and the resulting electrostatic potential. In this study, the guiding effect is observed to be dominated by the electric potential compared to the magnetic field. However according to the simulations, very high ion guiding efficiencies can be achieved using moderate magnetic fields and electrical potentials. Furthermore, it is demonstrated that the experiemental and calculated efficiencies agree well. Consequently, the simulation is the basis for a further optimization of the filtered ion beam sputtering processes. © 2015 SPIE.DFG/EXC/QUES

Electronic quantization in dielectric nanolaminates

The scientific background in the field of the laser induced damage processes in optical coatings has been significantly extended during the last decades. Especially for the ultra-short pulse regime a clear correlation between the electronic material parameters and the laser damage threshold could be demonstrated. In the present study, the quantization in nanolaminates is investigated to gain a deeper insight into the behavior of the blue shift of the bandgap in specific coating materials as well as to find approximations for the effective mass of the electrons. The theoretical predictions are correlated to the measurements. © 2016 SPIE. Downloading of the abstract is permitted for personal use only.Ministry for Science and Culture of Lower SaxonyVolkswagen Stiftun

Improved LIDT values for dielectric dispersive compensating mirrors applying ternary composites

The present contribution is addressed to an improved method to fabricate dielectric dispersive compensating mirrors (CMs) with an increased laser induced damage threshold (LIDT) by the use of ternary composite layers. Taking advantage of a novel in-situ phase monitor system, it is possible to control the sensitive deposition process more precisely. The study is initiated by a design synthesis, to achieve optimum reflection and GDD values for a conventional high low stack (HL)n. Afterwards the field intensity is analyzed, and layers affected by highest electric field intensities are exchanged by ternary composites of TaxSiyOz. Both designs have similar target specifications whereby one design is using ternary composites and the other one is distinguished by a (HL)n. The first layers of the stack are switched applying in-situ optical broad band monitoring in conjunction with a forward re-optimization algorithm, which also manipulates the layers remaining for deposition at each switching event. To accomplish the demanded GDD-spectra, the last layers are controlled by a novel in-situ white light interferometer operating in the infrared spectral range. Finally the CMs are measured in a 10.000 on 1 procedure according to ISO 21254 applying pulses with a duration of 130 fs at a central wavelength of 775 nm to determine the laser induced damage threshold. © 2016 SPIE. Downloading of the abstract is permitted for personal use only.DFG/EXC/QUESTVolkswagen StiftungBMBF/13N1155

Precise fabrication of ultra violet dielectric dispersion compensating mirrors

The present contribution is concentrated on an improved method to manufacture dielectric dispersion compensating mirrors in the ultra violet (UV) range by applying a novel online phase monitoring device. This newly developed measurement tool monitors the group delay (GD) and group delay dispersion (GDD) of the electromagnetic field in situ during the deposition of the layer system. Broad band monitoring of the phase enhances the accuracy in the near infrared spectral range (NIR), significantly. In this study, the correlation of the GDD in the NIR and in the UV spectral range is investigated. A design synthesis is introduced to achieve optimum reflection and GDD target values in the UV and NIR. This requires a similar behavior of both bands according to deposition errors, to guarantee switching off the UV GDD target band proper, while monitoring the GDD in the NIR spectral range. The synthesis results in a design, characterized by a GDD of -100fs2±20fs2 between 330nm and 360nm in the UV and by -450fs2±10fs2 within 820nm to 870nm in the NIR. The fabricated sample, applying an ion beam sputtering process, consists of a 9μm layer stack of Hafnium oxide and Silicon dioxide. The first layers of the stack are switched and controlled by a conventional in situ spectrometric broad band monitoring in conjunction with a forward re-optimization algorithm, which also manipulates the layers remaining for deposition at each switching event. To accomplish the demanded GDD-spectra, the last layers are controlled by the novel in situ GDD monitor. © 2015 SPIE.DFG/EXC/QUESTDFG/13N1155

The effect of visual suggestion on exercise motivation and outcomes

Theories of suggestion and motivation were used to examine if college students exercising in an environment with low or high motivation posters would affect mood, perceived exertion, and exercise workload (i.e., RPM and speed). A total of 134 students (62 males, 72 females) were randomly assigned to one of three conditions while exercising: relaxing posters (i.e., tropical nature), motivational posters (i.e., competitive bikers), or no posters (i.e., control). Participants completed 20 minutes of exercise at their own pace. Measures of mood were taken immediately prior to and following exercise. Exercise workload was recorded throughout. Results indicate that participants in the relaxing condition experienced higher levels of tension than those in the other two conditions. Participants in the motivational condition reported higher levels of relaxation. A consistency bias may have made participants uncomfortable in an exercise environment with relaxing images that are inconsistent with a typical exercise atmosphere

Imaging beta-adrenoceptors in the human brain with (S)-1'-[F-18]fluorocarazolol

We evaluated the suitability of fluorocarazolol for in vivo studies of cerebral beta-adrenoceptors because (S)-1'-[F-18]fluorocarazolol has a higher affinity to beta-adrenoceptors than to serotonergic receptors (pK(i) beta(1) 9.4, beta(2) 10.0, 5HT(1A) 7.4, 5HT(1B) 8.1) and rapidly crosses the blood-brain barrier. Methods: The (S)-[F-18]fluorocarazolol (74 MBq, >37 TBq/mmol) was intravenously administered to healthy volunteers on two separate occasions with an interval of at least 1 wk, The initial injection was without pretreatment, but before the second injection, the volunteers received the beta blocker (+/-)-pindolol (3 x 5 mg orally, during 18 hr). The brain was studied with a PET camera in dynamic mode. Results: Uptake of radioactivity delineated gray matter and was particularly high in the posterior cingulate, precuneus and striatum, Low uptake occurred in the thalamus, whereas the lowest uptake was observed in the white matter of the corpus callosum. After pindolol pretreatment, uptake was reduced and its distribution became homogeneous throughout the brain, The ratio of total-to-nonspecific binding was about 2 at 60 min, increasing to 2.5-2.75 at longer intervals. Conclusion: Fluorocarazolol is the first radioligand that can visualize cerebral beta-adrenoceptors and may enable monitoring of these binding sites during disease