The reader is provided with information about methods of calibration of light sources and photodetectors as well as responsiveness of spectral instruments ranging from near infrared to vacuum UV spectral, 1200 - 100 nm, and radiation intensities of up to several quanta per second in absolute and arbitrary units. The author describes for the first time original methods of measurements they created and draws upon over 40 years of experience in working with light sources and detectors to provide accurate and precise measurements. This book is the first to cover these aspects of radiometry and...