Cover Story

Laser Opto-Acoustic Imaging: Let There Be Light That Sounds!

Howard Nathel

Ultrasonic imaging is versatile, noninvasive, portable, relatively inexpensive, and is second only to X-ray in annual procedural volume. Optical imaging continues to search for an identity in the medical arena. Opto-acoustic tomography... more>>


Therapeutic Lasers and Optical Diagnostic Technology in Dentistry

Daniel Fried


Optical Tools Offer Minimally Invasive Medical Diagnostics

Yvonne Carts-Powell

Optical imaging and spectroscopy can be applied to a wide variety of medial diagnostic tests, including screening for early signs of cancer. more>>

The van Cittert-Zernike Theorem

Masud Mansuripur

Our goal is to present a simple derivation of the van Cittert-Zernike theorem without invoking the theories of probability and stochastic processes. This is possible because most sources of practical interest are ergodic, meaning that time-averaging over a typical waveform emanated by the source yields statistical information about the source's inherently random radiation processes. We shall make exclusive use of time-averaging to derive the degree of coherence of a pair of points within the field of an extended, quasi-monochromatic, incoherent source. more>>

High-NA Pickup Objective for High-Density Media

W. T. Silfvast, O. R. Wood II, J. J Macklin, and H. Lundberg

In 1967 Duguay and Rentzepis suggested the possibility of producing population inversions at short wavelengths by x-ray photoionization of inner-shell p-electrons in atomic species. Instead, the present work uses inner-shell d-electron removal (which has a larger cross section) and improves the pumping efficiency to a specific state by concentrating on species with closed outer shells. The concept of efficient broadband pumping with laser-produced plasmas, as proposed by Harris et al. and demonstrated by Caro et al. at Stanford University, to produce metastable states was also incorporated into this work. more>>