October 2002

Coronas and Iridescent Clouds

Joseph A. Shaw and Paul J. Neiman

Coronas and iridescence occur when light is diffracted by small particles of liquid water or ice in the atmosphere. Diffraction colors are particularly vivid in mountain wave clouds because of the small particles and narrow particle-size distributions. The photographs shown here provide evidence that wave cloud diffraction displays are often created by unusually tiny, quasi-spherical ice particles.

The Dye Transfer Color Print Process

For half of the 20th century, people who wanted the very best color prints, and for whom price was no object, demanded dye transfer prints. By the dawn of the new millennium, however, dye transfer printing had largely vanished from the scene. A professional photographer explains why the dye transfer process dominated the field of quality printing for so many years and describes how a range of economic and technological factors ultimately led to its decline.

Free Space Optics for Laser Communication Through the Air

Free space optics (FSO) communication involves the use of modulated optical or laser beams to send telecommunication information through the atmosphere. The concept of FSO light communication is not new: in his photophone patent of 1880, Alexander Graham Bell demonstrated use of an intensity-modulated optical beam (sunlight) to transmit telephone signals 200 m through the air to a distant receiver.

Optics and Information Technology

How optical scientists work and what they can make has changed profoundly with the information technology revolution of the past 50 years. The software packages developed to aid in the traditional activities of lens and coating design are now several generations old. New programs capable of tackling increasingly sophisticated optical problems are emerging: examples include optimization packages for non-imaging optics in illumination and programs to model the complex physics of multichannel, multiwavelength, fiber-optic telecommunications systems.


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