Optical Imaging and Spectroscopy

WAVE IMAGING

The physical phenomenon called diffraction is of the utmost importance in the theory of optical imaging systems.

—J. W. Goodman [100]

4.1 WAVES AND FIELDS

The optical field is an electromagnetic field. The physical nature of the field is determined by the laws of electromagnetic propagation and by quantum mechanical and thermal laws describing the interaction between the field and materials. In the design and analysis of optical systems we consider

• How the field is generated. Common mechanisms include

• Thermal radiation generated, for example, by the Sun, a flame, or an incandescent lightbulb
• Electrical discharge by gases such as neon or mercury vapor
• Fluorescence
• Electrical recombination in semiconductors

While we do not consider light generation in detail in this text, differences in the coherence properties of the source are central to our discussion. Coherence theory, which relates the electromagnetic nature of the field to statistical properties of quantum (e.g., photonic) processes, is the focus of Chapter 6.

• How the field is detected. The field may be detected by optically induced chemical, physical, thermal, and electronic effects. Optoelectronic detection interfaces for imaging and spectroscopy are the focus of Chapter 5.
• How the field propagates and how propagating fields are modulated by materials. Field propagation is described by the Maxwell equations ...