Byron M. Welsh

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Simulating the effects of atmospheric turbulence on optical imaging systems is an important aspect of understanding the performance of these systems. Simulations are particularly important for understanding the statistics of some adaptive-optics system performance measures, such as the mean and variance of the compensated optical transfer function, and for(More)
The performance of ground-based optical imaging systems is severely degraded from the diffraction limit by the random effects of the atmosphere. Adaptive-optics techniques have been used to compensate for atmospheric-turbulence effects. A critical component in the adaptive-optics system is the wave-front sensor. At present, two types of sensors are common:(More)
This paper uses the fact that the discrete Fourier transform diagonalizes a circulant matrix to provide an alternate derivation of the symmetric convolution-multiplication property for discrete trigonometric transforms. Derived in this manner, the symmetric convolution-multiplication property extends easily to multiple dimensions using the notion of block(More)
We have previously shown that daily application of 0.05% retinoic acid to the backs of lightly pigmented, hairless HRA:Skh-2 mice increases melanogenesis resulting from exposure to solar-simulated ultraviolet radiation. In this study we show that as early as 1 wk following commencement of treatment, there is a 2- fold increase in the number of epidermal(More)
Because of mechanical aspects of fabrication, launch, and operational environment, space telescope optics can suffer from unforeseen aberrations, detracting from their intended diffraction-limited performance goals. We give the results of simulation studies designed to explore how wave-front aberration information for such near-diffraction-limited(More)
One method for improving the quality of astronomical images measured through a atmospheric turbulence uses simultaneous short-exposure measurements of both an image and the output of a wave-front sensor exposed to an image of the telescope pupil. The wave-front sensor measurements are used to reconstruct an estimate of the instantaneous generalized pupil(More)
Quadratic aberration is successfully corrected with a segmented microelectromechanical deformable mirror in conjunction with a refractive lenslet array. Use of the lenslet array greatly improves the effective fill factor of the correcting element. Experimental results show correction approaching the diffraction limit for an extreme spherical aberration.
The bistatic imaging lidar technique is fundamentally different from traditional monostatic lidar techniques. The vertical density of an atmospheric layer, such as the mesospheric sodium layer, is measured by imaging an illuminated spot within the layer. The spot is illuminated with a laser and imaged with a telescope in a bistatic configuration. Profiles(More)
Adaptive optics system (AOS) performance is a function of the system design, seeing conditions, and light level of the wave-front beacon. It is desirable to optimize the controllable parameters in an AOS to maximize some measure of performance. For this optimization to be useful, it is necessary that a set of image-quality metrics be developed that vary(More)