Book excerpt: Knowledge of instrumentation is critical in light of the highly sensitive and precise requirements of modern processes and systems. Rapid development in instrumentation technology coupled with the adoption of new standards makes a firm, up-to-date foundation of knowledge more important than ever in most science and engineering fields. Understanding this, Robert B. Northrop produced the best-selling Introduction to Instrumentation and Measurements in 1997. The second edition continues to provide in-depth coverage of a wide array of modern instrumentation and measurement topics, updated to reflect advances in the field. See What's New in the Second Edition: Anderson Current Loop technology Design of optical polarimeters and their applications Photonic measurements with photomultipliers and channel-plate photon sensors Sensing of gas-phase analytes (electronic "noses") Using the Sagnac effect to measure vehicle angular velocity Micromachined, vibrating mass, and vibrating disk rate gyros Analysis of the Humphrey air jet gyro Micromachined IC accelerometers GPS and modifications made to improve accuracy Substance detection using photons Sections on dithering, delta-sigma ADCs, data acquisition cards, the USB, and virtual instruments and PXI systems Based on Northrop's 40 years of experience, Introduction to Instrumentation and Measurements, Second Edition is unequalled in its depth and breadth of coverage.