Accelerated phase retrieval using adaptive support and statistical fringe processing of phase estimates.

A technique for accelerated multiple-plane phase retrieval is demonstrated by creating adaptive support through the statistical analysis of phase estimates. Its technical advantage arises from, what we believe to be, the first time use of both phase estimates and a statistical metric, enabling the fast generation of noise-robust support masks. This results in a fourfold improvement in convergence speed when compared to the conventional multiple-plane method. Evaluating data fitting performance with fewer intensity recordings showed that using four or more recordings resulted in accurate fitting, three recordings caused overfitting, and two recordings led to underfitting for the test object waves used. In principle, the adaptive support strategy based on the statistical analysis of phase estimates may be applied to other iterative phase retrieval methods.

Accelerated single-beam multiple-intensity reconstruction using unordered propagations.

In conventional multiple-plane phase retrieval method, the wave propagations that proceed in the same ordered sequence could slow down convergence or lead to stagnation. In this Letter, a novel, to the best of our knowledge, algorithmic technique to accelerate phase retrieval using an unordered sequence of propagations is demonstrated experimentally. The main advantage of the technique is the significant increase in the change in amplitude, a key and essential element for a successful iterative phase retrieval. For N planes, the number of possible ways to implement the sequence of propagations is increased by a factor of N!(N-1)!, providing diversity for the change in the amplitude. Compared to the conventional algorithm, the technique performed 2 times faster and reduced the number of needed intensity patterns for the test object wave used. The technique may be adopted in the other multiple intensity-based phase retrieval methods.

Enhanced multiple-plane phase retrieval using adaptive support.

In the single-plane phase retrieval method, the use of a fixed object support is not efficient and could lead to inaccurate reconstructions. While there have been adaptive support strategies for the single-plane method, numerical processing is slow because such strategies are based in the space domain. Here, an adaptive support strategy based in the Fourier domain in conjunction with the multiple-plane phase retrieval method is presented and demonstrated through simulations and experiments. Optimizations of Fourier filter size and mask threshold parameters result in 3× faster convergence compared to the conventional multiple-plane method for the test object waves used. The proposed strategy offers fast, automated determination of the object support and affords the use of fewer intensity patterns.

Enhanced intensity variation for multiple-plane phase retrieval using a spatial light modulator as a convenient tunable diffuser.

In the multiple-plane phase retrieval method, a tedious-to-fabricate phase diffuser plate is used to increase the axial intensity variation for a nonstagnating iterative reconstruction of a smooth object wavefront. Here we show that a spatial light modulator (SLM) can be used as an easily controllable diffuser for phase retrieval. The polarization modulation at the SLM facilitates independent formation of orthogonally polarized scattered and specularly reflected beams. Through an analyzer, the polarization states are filtered enabling beam interference, thereby efficiently encoding the phase information in the axially diverse speckle intensity measurements. The technique is described using wave propagation and Jones calculus, and demonstrated experimentally on technical and biological samples.

Extending psychosocial assessment of patients with psoriasis in the UK, using a self-rateds, web-based survey.

BACKGROUND: Quality of life self-rating using a web-based survey has not previously been evaluated for psoriasis in the UK. AIM: To use an open-access web-based survey to assess the effect of psoriasis on patients' daily life. Methods. The survey was conducted using a dedicated website endorsed by a UK psoriasis patient charity. RESULTS: In total, 1760 patients (1102 women, 658 men; median age range 40-44 years) assessed their psoriasis using the website. Psoriasis was 'very' or 'extremely' active in 52%, and 71% had been diagnosed > 10 years previously. Psoriasis had negatively affected the working life of 59% of patients, and the educational performance of 31%. CONCLUSIONS: The use of an open-access web-based survey may address potential bias in previous studies, but may itself introduce a bias towards younger patients. This is the first report of a web-based survey of UK patients with psoriasis, providing further recent evidence of how psoriasis affects patients' lives.

Enhanced deterministic phase retrieval using a partially developed speckle field.

A technique for enhanced deterministic phase retrieval using a partially developed speckle field (PDSF) and a spatial light modulator (SLM) is demonstrated experimentally. A smooth test wavefront impinges on a phase diffuser, forming a PDSF that is directed to a 4f setup. Two defocused speckle intensity measurements are recorded at the output plane corresponding to axially-propagated representations of the PDSF in the input plane. The speckle intensity measurements are then used in a conventional transport of intensity equation (TIE) to reconstruct directly the test wavefront. The PDSF in our technique increases the dynamic range of the axial intensity derivative for smooth phase objects, resulting in a more robust solution to the TIE. The SLM setup enables a fast and accurate recording of speckle intensity. Experimental results are in good agreement with those obtained using the iterative phase retrieval and digital holographic methods of wavefront reconstruction.

Vibration detection using focus analysis of interferograms.

This paper proposed an automated technique for vibration detection using statistical focus measure to evaluate interferogram contrast. An interferogram sequence from a Mach-Zehnder interferometer setup is recorded (frame rate: 24 fps) and the gray-level variance (GLVA) is plotted versus time. Occurrence of induced vibration in the setup causes a decrease in the interferogram contrast which, in turn, manifests as an evident rapid drop in the variance plot. The technique is demonstrated experimentally using periodic microvibrations (frequency range, ≤6 Hz) and aperiodic disturbances.

Numerical correction of optical vortex using a wrapped phase map analysis algorithm.

We demonstrate experimentally a technique for the numerical correction of an optical vortex with a unitary topological charge. A developed algorithm based on the axial behavior of a reconstructed wavefront is used in the detection of the optical vortex. Optimizations of the number of axial phase maps and the window size used in the algorithm yield the precise coordinates of the vortex eye. The obtained coordinates and vortex handedness are used in designing a proper filter, facilitating numerical correction of the vortex phase map. The developed algorithm can be applied to absolute phase and phase difference maps obtained through any reconstruction method.

Current application of National Institute for Health and Clinical Excellence (NICE) guidance in the management of patients with severe psoriasis: a clinical audit against NICE guidance in seven National Health Service specialist dermatology units in England.

BACKGROUND: Psoriasis affects 1-2% of the U.K. population, with 20-30% of those affected having severe psoriasis managed with systemic therapies. Biological agents are a useful option when other systemic therapies have failed. The National Institute for Health and Clinical Excellence (NICE) in the U.K. has published three sets of guidance relating to the use of biological agents. AIM: To establish whether biological agents were being used in line with NICE guidance. METHODS: The study was conducted in seven specialist dermatology units, and involved the retrospective collection of data from patients treated with biological agents since the introduction of the NICE guidance. RESULTS: In total, 176 patients with 212 episodes of treatment were included in the study. Biologics were started for appropriately severe disease in 85% of cases (n = 180) and only after failure, intolerance or contraindication to standard systemic therapies in 97% of cases (n = 206). Etanercept was discontinued appropriately in responders before week 24 in only 12% (five of 60 responders). Across all agents, 40% (72 of 178 with continuity status) were continued on treatment despite not achieving an adequate response according to NICE criteria. CONCLUSIONS: In the seven sites audited, compliance with national guidance was entirely appropriate in terms of therapy initiation; however, the requirement to discontinue etanercept in responders was rarely followed. Similarly, discontinuation of biologicals in nonresponders was not routine practice. This may indicate a reluctance of both patients and clinicians to withdraw an at least partly effective therapy from these refractory patients.

Single-plane multiple speckle pattern phase retrieval using a deformable mirror.

A design for a single-plane multiple speckle pattern phase retrieval technique using a deformable mirror (DM) is analyzed within the formalism of complex ABCD-matrices, facilitating its use in conjunction with dynamic wavefronts. The variable focal length DM positioned at a Fourier plane of a lens comprises the adaptive optical (AO) system that replaces the time-consuming axial displacements in the conventional free-space multiple plane setup. Compared with a spatial light modulator, a DM has a smooth continuous surface which avoids pixelation, pixel cross-talk and non-planarity issues. The calculated distances for the proposed AO-system are evaluated experimentally using the conventional free-space phase retrieval setup. Two distance ranges are investigated depending on whether the measurement planes satisfy the Nyquist detector sampling condition or not. It is shown numerically and experimentally that speckle patterns measured at the non-Nyquist range still yield good reconstructions. A DM with a surface height of 25 microns and an aperture diameter of 5.2 mm may be used to reconstruct spherical phase patterns with 50-micron fringe spacing.

Quantization analysis of speckle intensity measurements for phase retrieval.

Speckle intensity measurements utilized for phase retrieval (PR) are sequentially taken with a digital camera, which introduces quantization error that diminishes the signal quality. Influences of quantization on the speckle intensity distribution and PR are investigated numerically and experimentally in the static wavefront sensing setup. Results show that 3 to 4 bits are adequate to represent the speckle intensities and yield acceptable reconstructions at relatively fast convergence rates. Computer memory requirements may be eased down by 2.4 times if a 4 bit instead of an 8 bit camera is used. This may facilitate rapid speckle data acquisition for dynamic wavefront sensing.

Phase microscopy of technical and biological samples through random phase modulation with a diffuser.

A technique for phase microscopy using a phase diffuser and a reconstruction algorithm is proposed. A magnified specimen wavefront is projected on the diffuser plane that modulates the wavefront into a speckle field. The speckle patterns at axially displaced planes are sampled and used in an iterative phase retrieval algorithm based on a wave-propagation equation. The technique offers a whole-field and high-resolution wavefront reconstruction of unstained microstructures. Phase maps of photoresist targets and human cheek cells are obtained to demonstrate the effectiveness of our method.

Renal function changes and NHS resource use in breast cancer patients with metastatic bone disease treated with IV zoledronic acid or oral ibandronic acid: a four-centre non-interventional study.

AIMS: To describe renal function monitoring practice in patients with metastatic bone disease (MBD) treated with IV zoledronic acid (ZA) and oral ibandronic acid (IA), the management pathways and NHS hospital resources used. METHODS: Medical records of 189 patients; IA (91), ZA (98) with primary breast cancer and MBD were reviewed, and data collected on renal monitoring and hospital visits during bisphosphonate therapy. Time and motion review of resources to administer the bisphosphonates was also conducted. RESULTS: Only 30% of patients given ZA and no patient given IA had baseline creatinine clearance (CrCl) recorded. Calculated baseline CrCl suggested impaired renal function in 33% ZA and 29% IA patients. Dose reductions were not made correctly in 29 ZA and 2 IA patients whose monitoring suggested it. ZA patients made more clinic and day care attendances than IA-treated patients, at twice the cost. Staff activity and patient time per visit was higher with ZA than IA. CONCLUSION: Although limited by retrospective design, these results demonstrate that in many patients, CrCl is not calculated before or during treatment with bisphosphonates. Renal function deteriorated in many patients during therapy. In view of these effects, practice should be reviewed to ensure appropriate dosing.

Numerical correction of aberrations via phase retrieval with speckle illumination.

What we believe to be a novel technique for wavefront aberration measurement using speckle patterns is presented. The aberration correction is done numerically. A tilted lens is illuminated with a partially developed speckle field, and the transmitted light intensity is sampled at axially displaced planes. The speckle intensity patterns are then sent to a phase-retrieval algorithm to reconstruct the complete wavefront. The nature of the wavefront aberration is determined through Zernike polynomials. Numerical correction of the perturbed wavefront is performed based on rms error and the Strehl ratio. Restoration of the wavefront from a phase object with high spatial frequency content shows the effectiveness of our method.

Fast-convergent algorithm for speckle-based phase retrieval and a design for dynamic wavefront sensing.

Wavefront reconstruction is carried out using sequentially recorded speckle patterns and an iterative phase retrieval method based on wave propagation. A novel fast-convergent algorithm that maintains the propagation distance in the iteration step equal to the distance between measurement planes is demonstrated. Employing the new algorithm, influences of the number of measurement planes, number of iterations, and uncertainties in the detector's transverse and axial positions on the rate of phase convergence are analyzed experimentally. A conceptual design for a dynamic wavefront sensor using arrays of beam splitters and detectors for parallel speckle recording is described.

Angular displacement and deformation analyses using a speckle-based wavefront sensor.

Wavefronts incident on a random phase plate are reconstructed via phase retrieval utilizing axially displaced speckle intensity measurements and the wave propagation equation. Retrieved phases and phase subtraction facilitate the investigations of wavefronts from test objects before and after undergoing a small rotation or deformation without sign ambiguity. Angular displacement (Deltatheta) between incident planar wavefronts is determined from the light source vacuum wavelength (lambda) divided by the fringe spacing (Lambda). Fourier analysis of the wavefront phase difference yields a peak frequency that is inversely proportional to Lambda, and the sign gives the direction of rotation. Numerical simulations confirm the experimental results. In the experiments, the smallest Deltatheta measured is 0.031 degrees . The technique also permits deformation analysis of a reflecting test object under thermal loading. The technique offers simple, high resolution, noncontact, and whole field evaluation of three-dimensional objects before and after undergoing rotation or deformation.

Interferometric evaluation of angular displacements using phase retrieval.

Phase retrieval is carried out using sequential intensity measurements of a volume speckle field and a wave propagation equation. Retrieved phases and phase subtraction facilitate the analysis of wavefronts before and after undergoing a small rotation. Angular displacement between incident planar wavefronts is determined from the unwrapped phase difference, phase diffuser aperture diameter, and the light source wavelength. Numerical simulations confirm the experimental results.

[Bilateral ostial coronary lesion in cardiovascular syphilis: case report]. / Lesão bilateral dos óstios coronários na sífilis cardiovascular: relato de caso.

Syphilis is an infectious disease occurring through a series of frequently overlapping stages. It can impair the cardiovascular and neurological system. In 30% of the non treated patients, syphilis develops its tertiary form. We report a case of a 46-year-old male patient admitted due to edema pulmonary and acute coronary syndrome with left bundle branch block, submitted to fibrinolytic therapy successfully. Coronary angiography showed a 90% ostial lesion of left main coronary artery and occlusion of the right coronary artery ostium. VDRL was titrated to 1/128. The patient was undergone to CABG and was discharged after treatment with crystalline penicillin.

Wavefront sensing using speckles with fringe compensation.

Wavefront sensing with numerical phase-error correction system is carried out using a random phase plate and phase retrieval using multiple intensity measurements of axially-displaced speckle patterns and the wave propagation equation. Various wavefronts with smooth curvatures incident on the developed phase plate (DPP) are examined: planar, spherical, cylindrical, and a wavefront passing through the side of a bare optical fiber. Spurious fringe pattern in the wavefront reconstructions due to a small tilt (Delta theta=0.212 degrees) in the plane illumination wave is detected and numerically corrected for. Fringe pattern of the illumination wave obtained for the setup without the phase object being investigated is used as reference fringe pattern. Fringe compensation yields wavefronts with the correct shape and numerical value based on the specifications of the setup. The numerical phase-error correction system described in this study can be extended to other types of phase errors such as those due to aberrations if optical elements are present in the setup or due to perturbations in the environment.