Showing papers in "Progress in Optics in 1978"

III Computer-Generated Holograms: Techniques and Applications

Abstract: Publisher Summary This chapter describes the techniques and applications of computer-generated holograms. “Computer-generated holograms,” “synthetic holograms,” and “computer holograms” are terms used to refer to a class of holograms that are produced as graphical output from a digital computer. Given a mathematical description of a wavefront or an object represented by an array of points, the computer can calculate the amplitude transmittance of the hologram and display the result on a CRT or plot it on paper. Using photoreduced copy of the graphical output from a computer as holograms is only one of the many things that distinguish computer generated holograms from conventional ones. The computer-generated holograms have their greatest potential in the area of interferometry. They have been shown to be useful in supplementing existing methods of optical testing. Laser beam scanning is another promising area for computer-generated holograms. Holographic grating scanners are in many ways better than other mechanical mirror scanners.

IV Speckle Interferometry

Abstract: Publisher Summary This chapter discusses the nature of the speckle pattern and defines some of its basic characteristics. The speckle effect in optics is the generation of a random intensity pattern formed when coherent light is scattered by a rough surface or is diffused by a medium containing scattering centers. The chapter concentrates on the instrumental aspects of speckle interferometry and their applications rather than a detailed theoretical treatment. It is seen that a considerable degree of ingenuity has had to be employed to overcome the inherent difficulties that occur when interference takes place among randomly distributed phase fields rather than among smoothly varying ones. Although the aim of the research is to develop techniques useful to the engineer, developments are also being made in the use of speckle patterns for information processing, where the pattern is employed as an optical carrier.

V Deformation Invariant, Space-Variant Optical Pattern Recognition

Abstract: Publisher Summary This chapter is concerned with optical pattern recognition applications. Specifically, it considers practical pattern recognition problems in which differences exist between the input and reference functions to be correlated. The approach to be emphasized involves the development of space-variant optical pattern recognition systems that are invariant to various expected deformations that can arise between the input and reference functions to be correlated. The specific type of space-variant optical processor is realized by applying a coordinate transformation preprocessing operation to the input and reference data. The vital approach to optical pattern recognition is needed if optical correlators are to see extensive use in real, practical applications and if they are to supplant sophisticated digital pattern recognition systems with their extensive algorithms but slow speed high cost.

VI Light Emission from High-Current Surface-Spark Discharges

Abstract: Publisher Summary This chapter discusses light emission from high-current surface-spark discharges. The distinguishing characteristic of a surface spark is the presence of a dielectric solid adjacent to the discharge channel. This surface that bounds the discharge plasma in at least one dimension affects the gas-dynamic and radiative properties of the spark such that notable differences exist between surface discharges and unconfined discharges. When compared with other pulsed incoherent light sources, high current surface-spark sources have notable differences and practical advantages, which make them attractive for a number of applications, particularly in gas laser development. With their simplicity and reliability, surface-spark sources offer attributes that are particularly significant for gas laser research, where efficient, intense uv-source arrays are often needed for photoionization, photoinitiation, or photodissociation. The chapter explains that this review stimulates further research into the spectral behavior of high-current surface discharges and promotes their utilization in new application areas.

I Laser Selective Photophysics and Photochemistry

Abstract: Publisher Summary This chapter discusses the laser selective photophysics and photochemistry. Currently, the investigations in the field of selective laser photophysics and photochemistry are being conducted in a great number of laboratories in several countries. This field lying on the border of quantum electronics, optics and spectroscopy, chemistry and technology of materials attracts many investigators. It is being actively discussed at international conferences. Laser isotope separation is undoubtedly one of the most important current problems of laser selective photophysics and photochemistry. Considerable progress has been achieved in this field and pilot installations for laser isotope separation are being created on a practical scale in some countries. The present state of this field of selective laser photophysics is considered in the chapter.

VII Semiclassical Radiation Theory within a Quantummechanical Framework

Abstract: Publisher Summary This chapter discusses the semiclassical radiation theory (SCT) within a quantum-mechanical framework. Recently, much interest has been exhibited in the validity of SCT. This interest has been partly generated by the widespread use of SCT in the analysis of many important phenomena such as laser operation, atomic and nuclear resonance effects, and photoelectric detection. The chapter looks at SCT as a part of quantum electrodynamics and reviews the work that indicates the conditions under which SCT is valid or may be considered a good approximation, from an orthodox quantum, mechanical viewpoint. Radiation theory refers to the interaction of the electromagnetic field with matter, and the kind of matter mainly under consideration in the chapter consists of microscopic systems of which only a few properties—dipole moment and energy spectrum—may be pertinent.