Hartmann’s procedure, first described by the French surgeon Henri Albert Hartmann in 1921, is one of the most commonly performed operations. This paper examines the history behind this operation and assesses its significance in modern surgical practice.

A Shack-Hartmann sensor is one of the most important and popular wavefront sensors used in an adaptive optics system to measure the aberrations caused by either atmospheric turbulence, laser transmission, or the living eye [1-7]. Its design was based on an aperture array that was developed in 1900 by Johannes Franz Hartmann as a means to trace individual rays of light through the optical system...

A new plastic microlens array, consisting of 900 lenslets, has been developed for the Shack Hartmann wave-front sensor.The individual lens is 300 µm × 300µm and has a focal length of 10 mm, which provides the same focal size, 60 µm in diameter, with a constant peak intensity. One can improve thewave-front measurement accuracy by reducing the spot centroiding error by averaging a few frame memor...

The theory, optical, mechanical, and software design for an interferometric Hartmann wavefront analyzer for the 6.5 m MMT is presented. The instrument is modular so it can be used at the prime focus or any of the three unique Cassegrain foci. We discuss the first results at the f/9 Cass focus where the detected wavefront error was used to correct both collimation and the primary mirror figure d...

In this research, turbulent MHD convection of liquid metal with constant and variable properties is investigated numerically. The finite volume method is applied to model the fluid flow and natural convection heat transfer in a square cavity. The fluid flow and heat transfer were simulated and compared for two cases constant and variable properties. It is observed that for the case variable pro...

"With the philosophy of Nicolai Hartmann we once again enter a world of sober, objective and impartial inquiry, which presses beyond man's self and seeks to grasp the universe of being so far as it is revealed to our limited capacity to know. The basic mood of Existence philosophy, as might be expected, is altogether missing from this universal way of viewing matters. (...). The true concern of...

Magnetohydrodynamic flow of an incompressible fluid through a plane channel with slowly varying walls and a magnetic field applied transverse to the channel is investigated in the high Reynolds number limit. It is found that the magnetic field can first influence the hydrodynamic flow when the Hartmann number reaches a sufficiently large value. The magnetic field is found to suppress the steady...

Phase estimates in adaptive-optics systems are computed by use of wavefront sensors, such as Shack-Hartmann or curvature sensors. In either case, the standard error of the phase estimates is proportional to the standard error of the measurements; but the error-propagation factors are different. We calculate the ratio of these factors for curvature and Shack-Hartmann sensors in dependence on the...

The wavefront-sensor is one of the most important components of any adaptive optics (AO) system. The simplicity of the Shack-Hartmann sensor has made it a popular choice for such systems. Its accuracy, which largely determines its performance depends on having a good and robust centroid algorithm. Despite a large number of studies, the general recipe for selecting the best centroiding algorithm...

In this paper, we investigate the effects of slip condition, transverse magnetic field and radiative heat transfer to unsteady flow of a conducting optically thin fluid through a channel filled with porous medium. Exact solution of the governing equations for fully developed flow is obtained in closed form. Detailed computations of the influence of the Grashof number, Hartmann number, slip para...