Purpose: To compare and analyze the differences in visual outcomes between Visx iDesign Advanced WaveScan Studio (TM) System, Alcon Wavelight Allegro Topolyzer and Nidek EC-5000 using Final Fit (TM) Custom Ablation Treatment Software from the submitted summary of safety and effectiveness of the US Food and Drug Administration (FDA) data. Methods: In this retrospective comparative study, 334 eyes from Visx iDesign, 212 eyes from Alcon Contour, and 135 eyes from Nidek CATz platforms were analyzed for primary and secondary visual outcomes. These outcomes were compared via side-by-side graphical and tabular representation of the FDA data. Statistical significance was calculated when appropriate to assess differences. A P-value <0.05 was considered statistically significant. Results: The mean postoperative uncorrected distance visual acuity (UDVA) at 12 months was 20/19.25 +/- 8.76, 20/16.59 +/- 5.94, and 20/19.17 +/- 4.46 for Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. In at least 90% of treated eyes at 3 months and 12 months, all three lasers showed either no change or a gain of corrected distance visual acuity (CDVA). Mesopic contrast sensitivity at 6 months showed a clinically significant increase of 41.3%, 25.1%, and 10.6% for eyes using Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. Photopic contrast sensitivity at 6 months showed a clinically significant increase of 19.2%, 31.9%, and 10.6% for eyes using Visx iDesign, Alcon Contoura, and Nidek CATz, respectively. Conclusion: FDA data for the three platforms shows all three were excellent with respect to efficacy, safety, accuracy, and stability. However, there are some differences between the platforms with certain outcome measurements. Overall, patients using all three lasers showed significant improvements in primary and secondary visual outcomes after LASIK surgery.

No description available.

The differential Optical Transfer Function (dOTF) is a focal plane wavefront sensing method that uses a diversity in the pupil plane to generate two different focal plane images. The difference of their Fourier transforms recovers the complex amplitude of the pupil down to the spatial scale of the diversity. We produce two simultaneous PSF images with diversity using a polarizing filter at the edge of the telescope pupil, and a polarization camera to simultaneously record the two images. Here we present the first on-sky demonstration of polarization dOTF at the 1.0m South African Astronomical Observatory telescope in Sutherland, and our attempt to validate it with simultaneous Shack-Hartmann wavefront sensor images.

We have proposed and demonstrated a technique for the measurement of the wavefront of a diode laser beam with a large dynamic range. Our technique is a modified version of Hartmann and Shack-Hartmann wavefront sensor. The modified version is capable of providing a large dynamic range (180 degrees). The wavefront measurement exhibits a precision of ( 0.02 degrees), subject to a standard deviation governed by the diffraction limit (~£f/d). Using the physical measurement of the wavefront, we are able to reconstruct the electric fields of a diode laser beam at any location, including the far-field and near-field. The reconstructed electric fields were computed form the data of the intensity and the phase distribution by means of Fourier transform. The information about the electric field can be very useful in the design of microlens for the efficient coupling of light source into optical components. The results indicate that the wavefront sensor with large dynamic range can provide a reliable method for measuring the wavefront distributions of diode lasers with large divergence angles. However, the numerical near-field intensity is 150% deviated from the measured near-field intensity because of the inherent inaccuracy in the wavefront measurement. In this study, we have measured the near field intensity distribution directly with an objective and a CCD camera. We found that the distribution of the mode field was symmetric at a distance of 8£gm from a diode laser and the mode field diameter was 4.75£gm. Using the phase retrieval algorithms, the radii of the near-field wavefront in the vertical axis and the horizontal axis were 8£gm and 41£gm, respectively. Through the geometrical optics, the optimum curvatures of elliptic-cone-shaped lensed fiber for efficient coupling in the vertical axis and the horizontal axis were 4£gm and 20.5£gm individually. Once we know the optimum curvatures of elliptic-cone- shaped lensed fiber, we can fabricate it using grinding and fusing.

Applying laser near-field wavefront reconstruction, we have discussed the coupling mechanism of the laser and optical lensed fiber. The coupling of the laser and optical lensed fiber is in the near-field range. In order to discuss the coupling mechanism of the laser and optical lensed fiber, we had to measure laser beam in near-field(including intensity and phase).The laser near-field intensity could be measured directly with an objective and a CCD camera. Because the laser spot size was too small, it was difficult to measure the laser near-field phase directly. Therefore, we used the phase retrieval algorithms, intercepting two groups of laser near-field intensity distribution plane to calculate laser near-field phase distribution. Combining laser near-field intensity distribution and phase distribution, we could rebuild laser beam in near-field. Lensed fiber is fabricated by means of grinding and fusing. We measured the coupling efficiency of the lensed fiber and laser diode(the wavelength of laser beam is 980nm), and simulated the surface of the lensed fiber with software. Applying beam propagation method, we could calculate the laser near-field distribution which propagated through lensed fiber, and cooperate the coupling efficiency of the lensed fiber and laser diode to explain the coupling mechanism. In summary, we discovered that the lensed fiber in the course of the coupling mechanism of the laser and optical lensed fiber changed the laser near-field phase from a bending curved surface into a flat curved surface just like the phase of plane wave, and it also improved the coupling efficiency.

In the aberration analysis of a wavefront over a certain domain, the polynomials that are orthogonal over and represent balanced wave aberrations for this domain are used. For example, Zernike circle polynomials are used for the analysis of a circular wavefront. Similarly, the annular polynomials are used to analyze the annular wavefronts for systems with annular pupils, as in a rotationally symmetric two-mirror system, such as the Hubble space telescope. However, when the data available for analysis are the slopes of a wavefront, as, for example, in a Shack-Hartmann sensor, we can integrate the slope data to obtain the wavefront data, and then use the orthogonal polynomials to obtain the aberration coefficients. An alternative is to find vector functions that are orthogonal to the gradients of the wavefront polynomials, and obtain the aberration coefficients directly as the inner products of these functions with the slope data. In this paper, we show that an infinite number of vector functions can be obtained in this manner. We show further that the vector functions that are irrotational are unique and propagate minimum uncorrelated additive random noise from the slope data to the aberration coefficients.

Wavefront sensing is an old yet fundamental problem in adaptive optics. Traditional wavefront sensors are limited to time-consuming measurements, complicated and expensive setup, or low theoretically achievable resolution. In this thesis, we introduce an optically encoded and computationally decodable novel approach to the wavefront sensing problem: the Coded Shack-Hartmann. Our proposed Coded Shack-Hartmann wavefront sensor is inexpensive, easy to fabricate and calibrate, highly sensitive, accurate, and with high resolution. Most importantly, using simple optical flow tracking combined with phase smoothness prior, with the help of modern optimization technique, the computational part is split, efficient, and parallelized, hence real time performance has been achieved on Graphics Processing Unit (GPU), with high accuracy as well. This is validated by experimental results. We also show how optical flow intensity consistency term can be derived, using rigor scalar diffraction theory with proper approximation. This is the true physical law behind our model. Based on this insight, Coded Shack-Hartmann can be interpreted as an illumination post-modulated wavefront sensor. This offers a new theoretical approach for wavefront sensor design.

No description available.

Standard adaptive optics systems measure the aberrations in the wavefronts of a beacon guide star caused by atmospheric turbulence, which limits the corrected field of view to the isoplanatic patch, the solid angle over which the optical aberration is roughly constant. For imaging systems that require a corrected field of view larger than the isoplanatic angle, a three-dimensional estimate of the aberration is required. We are developing a wide-field imaging Shack-Hartmann wavefront sensor (WFS) that will characterize turbulence over a large field of view tens of times the size of the isoplanatic angle. The technique will find application in horizontal and downward looking remote sensing scenarios where high resolution imaging through extended atmospheric turbulence is required. The laboratory prototype system consists of a scene generator, turbulence simulator, a Shack Hartman WFS arm, and an imaging arm. The system has a high intrinsic Strehl ratio, is telecentric, and diffraction limited. We present preliminary data and analysis from the system.

When light encounters scattering materials such as biological tissue, white paint or clouds, it gets randomly scattered in all directions, which traditionally has been seen as a barrier for imaging techniques (reducing their resolution) or sensing, due to the reduction of the penetration depth of light. However, in recent years it has been shown that scattering might not necessarily be an impediment, and that the knowledge of the properties of multiple scattering can be indeed useful for imaging, sensing and other applications. In the first part of this thesis (Chapters 2 to 5) we study the implications of manipulating the light incident on a multiply scattering material. We experimentally show how by actively controlling the output light of a bad quality laser we manage to not only improve its beam quality, but also in an energy-efficient way, in comparison with traditional methods. In a different experiment presented in this thesis, we show how the active control of the light incident on a scattering material can be useful to improve sensing through scattering media, by means of increasing the transmission and energy deposited inside (Chapter 5). In the final part of the thesis we present the first experimental observation of intensity correla- tions between transmitted and reflected patterns from a scattering material (Chapter 6), exploring how it depends on the parameters of the scattering medium. In the last part of the thesis (Chapter 7) we present a new imaging technique based on the use of the intensity correlations described in the previous chapter, opening new possibilities to non-invasive imaging through highly scattering materials.