Half a century has passed since Theodore Maiman's small ruby rod crossed the threshold of laser emission. The breakthrough demonstration earned headlines, but in the early years the laser was called "a solution looking for a problem," and there was a germ of truth in the joke. Years of development since then have vastly improved laser performance, and tremendously increased their variety, earning lasers important roles in scientific research, consumer products, telecommunications, engineering, medicine, materials working, and a host of other applications. This article reviews the highlights of those developments and puts them into context, showing how laser technology has evolved to meet application requirements.

https://www.spiedigitallibrary.org/journals/optical-engineering/volume-49/issue-9/091002/Short-history-of-laser-development/10.1117/1.3483597.pdf

Short history of laser development

Publisher Summary This chapter describes the fluctuations of light beams. Like other fluctuation problems concerned with departures from equilibrium, radiation fluctuations in an enclosure can be treated by the methods of statistical mechanics. The fluctuations of the counts recorded by a photo-detector illuminated by Gaussian light depart from classical statistics in such a way that the variance always exceeds that given by the Poisson distribution. The counts do not occur at random but exhibit a certain clustering or bunching effect characteristic of boson particles. If two light beams are partially coherent, this excess photon noise will be correlated in the two beams and is, therefore, responsible for the intensity correlation. The chapter discusses a method to examine the counting distribution. This method is also applicable to the calculation of the bunching effect. The chapter also describes a photo detector illuminated by polarized light of instantaneous intensity.

V Fluctuations of Light Beams

Half a century has passed since Theodore Maiman's small ruby rod crossed the threshold of laser emission. The breakthrough demonstration earned headlines, but in the early years the laser was called "a solution looking for a problem," and there was a germ of truth in the joke. Years of development since then have vastly improved laser performance,and tremendously increased their variety, earning lasers important roles in scientific research, consumer products, telecommunications,engineering, medicine, materials working, and a host of other applications. This article reviews the highlights of those developments and puts them into context, showing how laser technology has evolved to meet application requirements.

A short history of laser development

A new optical maser structure is described which reduces the threshold pumping power and increases the available output. It consists of a composite rod, which has a core of maser material (e.g., ruby) covered by a coaxial sheath of transparent refractive material (e.g., sapphire). Refraction of pumping light by the sheath is shown to increase the intensity at the active core. The structure also facilitates cooling by providing an increased surface area.

Composite Rod Optical Masers

Publisher Summary This chapter discusses the physical–chemical structure of chromia–alumina catalysts The chapter describes the molecular configurations of chromium in chromia–alumina catalysts and the possible relationships of these configurations to the catalytic properties of chromia–alumina At the smallest chromium contents ( 2 O 3 structure The large clusters of chromia that constitute the β phase, assume the thermodynamically more stable α-Cr 2 O 3 structure Because a greater percentage of the chromium ions are exposed in the low concentration range, a greater catalytic effect per chromium ion at low concentrations is expected The γ structure has a much more disordered crystallographic form than the α structure that is assumed by the β phase at large chromium contents

Lynn R. Sarles

Papers

Stimulated Optical Emission from Exchange-Coupled Ions of Cr + + + in Al 2 O 3