Optical imaging of Rydberg atoms

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 109-111).We present an experiment exploring electromagnetically induced transparency (EIT) in Rydberg atoms in order to observe optical nonlinearities at the single photon level. ⁸⁷Rb atoms are trapped and cooled using a magneto-optical trap (MOT) and a far off resonance dipole trap (FORT). Once the system is prepared, a ladder EIT scheme with Rydberg atoms is used to map the photon field onto the ensemble. The powerful dipole interaction between Rydberg atoms allows the system to exhibit many-body quantum mechanical effects. We also describe an imaging method to observe the Rydberg blockade. Last of all, we present a preliminary measurement of EIT in a Rydberg system. In this measurement, the transmission shows sensitivity to the applied photon flux, and exhibits temporal correlations in the photons exiting the EIT medium.by Anton Mazurenko.S.B

On the integration of deformation and relief measurement using ESPI

The combination of relief and deformation measurement is investigated for improving the accuracy of Electronic Speckle-Pattern Interferometry (ESPI) data. The nature of sensitivity variations within different types of interferometers and with different shapes of objects is analysed, revealing significant variations for some common interferometers. Novel techniques are developed for real-time measurement of dynamic events by means of carrier fringes. This allows quantification of deformation and relief, where the latter is used in the correction of the sensitivity variations of the former

Testing of displays of protection and control relays with machine vision

Human-machine interface is the link between a user and a device. In protection and control relays the local human machine interface consist of a display, buttons, light-emitted diode indicators and communication ports. Human-machine interfaces are tested before assembly with visual inspection to ensure quality of LCDs and LEDs. The visual inspection test system of HMIs consists of a camera and lens, a light emitted diode analyser, software and a computer. Machine vision operations, such as corner detection and template matching, are used to process and analyse captured images. Original camera and measurement device set-up have been used several years, and it should be upgraded. New camera and lens were installed in the system, and the aim of the thesis was to evaluate and improve the testing set-up and software to support each other, to get better images, and further, to improve the first pass yield. Camera position and settings were adjusted to capture images with good quality. Features of upgraded set-up and software were tested, and development ideas are given for further improvement. Changes in the set-up and software show promising results by giving more accurate test results from production.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Measurement of range of motion of human finger joints, using a computer vision system

Assessment of finger range of motion (ROM) is often required for monitoring the effectiveness of rehabilitative treatments and for evaluating patients' functional impairment. There are several devices which are used to measure this motion, such as wire tracing, tracing onto paper and mechanical and electronic goniometry. These devices are quite cheap, excluding electronic goniometry; however the drawbacks of these devices are their lack of accuracy and the time- consuming nature of the measurement process. The work described in this thesis considers the design, implementation and validation of a new medical measurement system utilized in the evaluation of the range of motion of the human finger joints instead of the current measurement tools. The proposed system is a non-contact measurement device based on computer vision technology and has many advantages over the existing measurement devices. In terms of accuracy, better results are achieved by this system, it can be operated by semi-skilled person, and is time saving for the evaluator. The computer vision system in this study consists of CCD cameras to capture the images, a frame-grabber to change the analogue signal from the cameras to digital signals which can be manipulated by a computer, Ultra Violet light (UV) to illuminate the measurement space, software to process the images and perform the required computation, a darkened enclosure to accommodate the cameras and UV light and to shield the working area from any undesirable ambient light. Two calibration techniques were used to calibrate the cameras, Direct Linear Transformation and Tsai. A calibration piece that suits this application was designed and manufactured. A steel hand model was used to measure the fingers joint angles. The average error from measuring the finger angles using this system was around 1 degree compared with 5 degrees for the existing used techniques

Optical instrumentation for fluid flow in gas turbines

Both a novel shearing interferometer and the first demonstration of particle image velocimetry (PIV) to the stator-rotor gap of a spinning turbine cascade are presented. Each of these techniques are suitable for measuring gas turbine representative flows. The simple interferometric technique has been demonstrated on a compressor representative flow in a 2-D wind tunnel. The interferometer has obvious limitations, as it requires a clear line of sight for the integration of refractive index along an optical path. Despite this, it is a credible alternative to schlieren or shadowgraph in that it provides both qualitative visualisation and a quantitative measurement of refractive index and the variables to which it is dependent without the vibration isolation requirements of beam splitting interferometry. The 2-D PIV measurements have been made in the stator-rotor gap of the MTI high-pressure turbine stage within DERA's Isentropic Light Piston Facility (lLPF). The measurements were made at full engine representative conditions adjacent to a rotor spinning at 8200 rpm. This is a particularly challenging application due to the complex geometry and random and periodic effects generated as the stator wake interacts with the adjacent spinning rotor. The application is further complicated due to the transient nature of the facility. The measurements represent a 2- D, instantaneous, quantitative description of the unsteady flow field and reveal evidence of shocks and wakes. The estimated accuracy after scaling, timing, particle centroid and particle lag errors have been considered is ± 5%. Non-smoothed, non-time averaged measurements are qualitatively compared with a numerical prediction generated using a 2-D unsteady flow solver (prediction supplied by DERA). A very close agreement has been achieved. A novel approach to characterising the third component of velocity from the diffraction rings of a defocusing particle viewed through a single camera has been explored. This 3-D PIV technique has been demonstrated on a nozzle flow but issues concerning the aberrations of the curved test section window of the turbine cascade could not be resolved in time for testing on the facility. Suggestions have been made towards solving this problem. Recommendations are also made towards the eventual goal of revealing a temporally and spatially resolved 3-D velocity distribution of the stator wake impinging on the passing rotor

Advanced Image Acquisition, Processing Techniques and Applications

"Advanced Image Acquisition, Processing Techniques and Applications" is the first book of a series that provides image processing principles and practical software implementation on a broad range of applications. The book integrates material from leading researchers on Applied Digital Image Acquisition and Processing. An important feature of the book is its emphasis on software tools and scientific computing in order to enhance results and arrive at problem solution

Morphodynamics, sedimentation and sediment dynamics of a gravel beach

The morphodyiiamics of a gravel barrier beadi in Devon, \JK (Slaptou Sands: tau/S 0.15 - 0.25, D50 2 - 8min), was studied with reference to its sedimentology. Three time scales were sampled for nearshore hydrodynamics, intertidal morphologies and sediirientologies. A series of surveys were carried out over individual tidal cycles (samphng every 5 - lOmins for between 6 and 91irs); on •consecutive low tides over half-lunar tidal cycles (1 -2 cross-shore profiles-sampled every 0.5 - Ini, on 2 spring - spring tidal cycles comprising 26 and 24 tides, respectively); and finally eveiy 2 weeks at spring low tide, over 1 calendar year (13-17 profile lines survej'ed and sampled for sediment over 3.25 - 4.251an). In order to further our understanding of gravel beaches, sediment data needs to, be collected at a resolution similar to that of the hydrodynamics. Innovative automatic sediment sizing techniques based on digital images of sediments were therefore developed, and software written, to allow the collection and analysis of high-resolution sediment data. The gi-avel beach step and berm are accretionaiy features, tidally modulated, and evolve under different time scales. A new technique to determine bed mobility from the nearshore, using underwater ^adeo cameras, was devised. Nearsliore sediment transport was suggested as being related to sub-incident wave frequencies. No aspect of morphological change could be found to havea statistically significant association with sedimentological change, but dimensional-reduction techniques did satisfactorily detect association. The lack of co-variance and obvious patterns is stochastic noise, not • parameterisation. Over one year, the barrier underwent asymmetrical rotation over one year, highlighting the importance of alongshore sediment transport processes on this supposedly 'swash aligned' beach. A statistical model based on the log-hj'perbolic distribution of sinface particle sizes was found to be a reasonable predictor of mean net sedimentation over individual tides. Its complicated parameter space could possibly map'onto a simpler plane based on traditional moments. Sediment trend vector models based on sorting alone out-performed a traditional approach. Moments of a surface grain-size'distribution appear to be inappropriate to characterise sedimentological change at time-scales gi-eater than a semi-diurnal tidal cycle. Sub-surface sampling on the intertidal zone on diurnal and semi-lunar time-scales is useful in assessing the dynamics of the step, itself an important mechanism for onshore and offshore net volumetric transport.School of Geograph

NASA Tech Briefs, November 2002

Topics include: a technology focus on engineering materials, electronic components and systems, software, mechanics, machinery/automation, manufacturing, bio-medical, physical sciences, information sciences book and reports, and a special section of Photonics Tech Briefs